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Temporal integration of loudness as a function of level
Florentine, Mary; Buus, Søren; Poulsen, Torben
Published in: Acoustical Society of America. Journal
Link to article, DOI: 10.1121/1.411567
Publication date: 1996
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Citation (APA): Florentine, M., Buus, S., & Poulsen, T. (1996). Temporal integration of loudness as a function of level. Acoustical Society of America. Journal, 99(3), 1633-1644. DOI: 10.1121/1.411567
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PROGRAM OF
The 129th Meeting of the AcousticalSociety of America
RenaissanceWashington, DC Hotel ©Washington, DC ©30 May-3 June 1995
NOTE: All Journalarticles and Letters to the Editorare peerreviewed before publication. Program abstracts,however, are not reviewedbefore publication, since we areprohibited by time andschedule.
TUESDAY MORNING, 30 MAY 1995 RENAISSANCE WEST A, 8:00 A.M. TO 12:00 NOON
SeSsionlaAO
AcousticalOceanography: Ocean Acoustic Tomography: Observing the Oceanin the 1990sI
Walter Munk, Cochair ScrippsInstitution of Oceanography,University of California,San Diego, La Jolla,California 92093
Brian D. Dushaw, Cochair AppliedPhysics Laboratory, University of Washington,Seattle, Washington 98105
Chair's Introduction4:00
Invited Paper
8:05
laAO1.Acoustic thermometry of oceanclimate (ATOC). WalterH. Munk (ScrippsInst. of Oceanog.,IGPP-0225, UCSD, La Jolla, CA 92093)
The rockyroad followed in the 1990sleading to thepresent status of acousticthermometry of oceanclimate (ATOC) will be reviewed.
ContributedPapers
8:30 to 10 000 km distantduring the Acoustic Engineering Test of theAcoustic Thermometryof OceanClimate (ATOC) Program.The sourcewas sus- laAO2. A comparison of measured and predicted broadband acousticarrival patterus out to 10-Mm range during the ATOC pendedfor 7 daysduring November 1994 near the depthof the sound Acoustic Engineering Test. Brace M. Howe, Brian D. Dushaw, James channelaxis (about 650 m) in waterover 4000 m deep,in orderto avoid A. Mercer,Robert I. Odom,Robert C. Spindel(Appl. Phys. Lab., Univ. of near-sourcebottom interactions.The sourcetransmitted a phase-coded Washington,Seattle, WA 98105), Peter F. Worcester,John Colosi, m-sequencewith a centerfrequency of 75 Hz anda digit lengthof 27 ms BraceD. Comuelle,Matthew Dzieciuch (Scripps Inst. of Oceanog.,Univ. [Metzgetet al., this m•eting].Measured receptions on five bottom- of Californiaat San Diego, La Jolla,CA 92093), Arthur B. Baggeroer mountedSOSUS receiversat rangesfrom 300-4000 kin, on two vertical (MIT, Cambridge,MA 02139), Ted Birdsall,Kurt Metzger (Univ. of line array receiversat ranges of 90 and 3300 km, and on a Sohobuoy Michigan, Ann Arbor, MI 48109), Gary Bold, Sze Tan, Chris Tindle modified to have the hydrophoneon the soundchannel axis at about (Univ. of Auckland, Auckland, New Zealand), and Michael Guthrie 10 000-kin range,are compared with ray theoretic,adiabatic normal mode, (DefenseScientific Establishment, Auckland, New Zealand) and broadbandparabolic equation predictions. [Work supportedby the A low-frequencyacoustic source suspended from R/P FLIP approxi- StrategicEnvironmental Research and DevelopmentProgram through mately340 nauticalmiles WSW of San Diego transmittedto receivers90 ARPA.]
3233 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3233
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 8:45 9:30 '; laAO3.Signal generation andproceSSing forthe R/P Flip ATOC laAO6. Are faster than predicted arrival times seeingArctic Ocean transmissions.Kurt Metzget and Ted Birdsall(CSPL, Univ. of warming?Peter N. Mikhalevsky(Sci. Appl. Intl. Corp.,McLean, VA Michigan,Ann Arbor, MI 48109-2122) 22102), AlexanderGayalloy (Andreev Inst. of Acoust.,Moscow, Russia), and ArthurB. Baggeroer(MIT, Cambridge,MA 02139) Thewaveforms transmitted during the November 1994 Acoustic Ther- Arrivaltimes of M sequencestransmitted across the Arctic in thespring mometryofOcean Climate (ATOC) project R/P Flip measu,rement usedan of 1994during the trans-Arctic acoustic propagation (TAP) experiment [P. m-sequencephase modulated 75-Hz carrier,two cardercycles per digit. N. Mikhalevsky,J.Acoust. Soc. Am. 95, 2851(A) (1994)] are faster than Because the soume had an inherent Q of 5, the drive waveform was modeledarrival times usinghistorical climatology. The modal dependence modifiedin orderto producea twocycle. per digit outputß This paper of the traveltimes appears to be consistentwith a warmingof the Atlantic describesthe basic characteristicsof the soume,the procedureused to intermediatewater (AIW) in the Arctic Ocean. Calculationsof the effects broadenthe sourcebandwidth, the enforcementof a soumepeak power of thistype of climatechange signal, as well as ambientvariability on the limit, and showsthe resultingwaveforms. The receivedwaveforms pos- modalarrival times, will be presented.The possibilitythat the TAP results sessedsmall amounts of Doppler"shift" caused by'the motion of Flip on areconsistent with newreports of AIW warmingin theArctic [Carmack its mooring.Doppler limits the amount of timeover which receptions can et al., Geophys.Res. Lett. (in press)and K. Aagaardand E. C. Carmack, be integrated.Doppler normally must be treatedas time compression/ Science266 (23 December1994)] will be discussed.[Work supported by expansion.However, if the Doppler is sufficiently small it canbe treated as ONR, ARPA,and the Ministry of Science,Russian Federation.] simpletime shift.This paper compares the results of usingboth approaches to accountfor themotion of Flip. [WorksupPorted by the StrategicEnvi- ronmentalResearch and Development Program through ARPA.]
9:45
laAO7. Long-distancelow-frequency modal propagation into the 9:00 LincolnSea. Rich Pawlowicz(Instl of OceanSci., P.O. Box 6000, Sidney,BC V8L 4B2, Canada),David M. Farmer(Inst. of OceanSci., laAO4.The response of acousticmeaSurements to anthropogenic Sidney,BC V8L 4B2, Canada),Barbara Sotirin (NCCOSC-RDTE, San climatechange. Matthew A. Dzieciuch(Scripps Inst. of Oceanog., Diego, CA 92152-5000), and Slobran Sozard(Univ. of Victoria, IGPP-0225,UCSD, La Jolla,CA 92093) Victoria,BC, Canada)
AnthropogenicCO2 in the atmosphereis expectedto result in in- One-Mm transmissionsfrom the April 1994 trans-Arctic acoustic creasedocean heating. The output of a coupledocean-atmospher• general propagation(TAp) experiment recorded bya verticalline array deployed circulationmodel was used tO simulateto expectedclimate changesce- from an icecampat the edgeof the continentalshelf in the Lincoln Sea are nario.The model was mn with no CO2 increase and with CO•2 doubling. analyzed.The [eceived phase is astonishinglystable, and appears to vary mainly with source/receivermotions. Travel times determinedfrom The spatialproperties of the CO2 signal are nonuniformand show that M-sequencetransmissions are less stable and are not consistentwith the heatingis not confinedto the oceansurface. The ambientclimate variabil- phasemeasurements. Modal decompositionshows that bottom effects strip ity showsa differentspatial structure that is moreemphasized at the sur- face.The GCM output was then used as an input to an acoustic propaga- out the higher-ordermodes as soundpropagates onto the shelf.The am- plitudeof the surface4rappedfirst mode is alsoweaker than predicted by tion model. The acoustictime seriescan then be analyzedfor climatic trends.The control mn is used to estimate the ambient noise processes on standardloss mechanisms. Some implications of this analysisfor the de- sign of future Arctic low-frequencytomography experiments are dis- long-termscales. Maps of the anthropogenicsignal to the ambientnoise cussed. ratio of the climatesystem can thenbe constructed.Acoustic thermometry measuresintegrals of heat contentthrough these maps. A network of sourcesand receiverscan then be designedto efficientlymonitor anthro- pogenicclimate change. Work is in progressto comparethe efficiencyof 10:00-10:15 Break different measurementsystems such as satellitealtimeters, drifters, and traditionalmeasurements to that of acousticthermometry.
10:15 9:15 laAO8.Use of simplifiedcoupled mode propagation for the laAOS.Stochastic modeling and global warming trend extraction prediction of impulse responses of megameter trans-Arctic propagation paths. Herbert A. Freese(Sci. Applic. Int. Corporation, for ocean acoustictravel times. StevenBottone (Mission Res. Corp., McLean, VA 22102) P.O. Drawer719, SantaBarbara, CA 93102-0719),Henry L. Gray,and WayneA. Woodward(Southern Methodist Univ., Dallas,TX 75275) In the springof 1994, a long-rangepropagation experiment was con- ductedin theArctic during which large time-bandwidth product signals (M A possibleindication of the existenceof globalclimate warming is a sequences)were transmitted to two receiversites. These data were pro- negativetrend for the travel time of an acousticpulse along a fixed long cessedto extract the pulse responseof the propagationchannel at the path,or paths,in the oceanover a periodof manyyears. Statistical meth- verticalarrays at eachsite and a horizontalarray at oneof the sites.These odsfor determiningwhether a significantlong term trend is presentin a data are beingused for an assessmentof the utility of Arctic acoustic given set of time seriesdata of acousticpropagation times have been measurementsfor globalwarming signature detection and monitoring.A developedand, for illustration,applied to somespecific travel-time time criticalpart of thismeasurement is the identificationof the observedpaths seriesgenerated by ih• MASiG m,d GFDL oceas•modds. Fo, the multiple with specificpropagating modes. A methodhas been developed based on pathcase, line + noisemodels, where the noise is modeledas a multivari- coupled normal modes which allows us to estimate pulse responses ate autoregressive(AR) processare considered.It is shownthat the time quickly.The resultsagree favorably with the experimentaldata when his- necessaryto detectthe presenceof a warming trend in a time seriesfor a toricalenvironment data are used as the model inputs. The modelingmeth- singlepath is reducedby consideringtime series for multiplepaths. [Work odsused, comparisons with the measurementsand implications,as well as sponsoredby ARPA.] the impacton soundspeed accuracy required, will be discussed.
3234 J.Acoust. soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society ofAmerica 3234
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 10:30 11:15
laAO9, On the feasibilityof modalgroup delay-based tomography laAO12. Internal wave effects on long-range ocean acoustic in the deep ocean. Michael G. Brown and John Viechnicki tomography.M. A. Wolfson,J. L. Spiesberger(Dept. Meteorol.and (RSMAS-AMP,Univ. of Miami,4600 Rickenbacker Cswy., Miami, FL ARL, PennState Univ., 602 Walker Building, University Park, PA 16802), 33149} and ED. Tappert(Univ. of Miami, Miami, FL 33149)
The modaldescription of soundpropagation in deepocean environ- Full-wavenumerical simulations of internalwave scattering of low- mentsis considered.Several recently published inversion algorithms have frequencysound in the deepocean are performed with an efficientbroad- assumedthat modalgroup time delayscan be measured.Such a measure- bandPE modelbased on a new parabolicapproximation that is second- mentrequires that the frequency bandwidth: (l) be sufficientlybroad that orderaccurate, and an internalwave model based on a newrepresentation successivemodal arrivals are resolvedin time, and (2) be sufficiently of theGM spectrumthat allows efficient generation of internalwave fields narrowthat, across the band,the groupslownesses of neighboringmode thatevolve in geophysicaltime. Results are displayed as plots of acoustic numbersdo notoverlap. These conflicting requirements can be reconciled traveltime versus geotime for varioussource-receiver separations (up to only at longrange. In the deepocean, the late arriving,low-order modes 8 Mm), andvarious center frequencies and bandwidths. Quantitative ex- are mostlikely to satisfycondition (2}. Unfortunately,recent measure- amination(coherent and incoherent geotime averages) yields information mentsand numerical simulations suggest that these modes are susceptible aboutthe temporal coherence and stability of eachmultipath. It is found to internalwave-induced mode coupling---especially at long range. The that the later near-axialarrivals are unstableand unresolvable,and there- followingpessimistic conclusion is made:Modal group delay-based inver- forenot usefulfor tomography,at rangesand frequencies that are consis- sionschemes can be appliedto measurementsof acousticwavefields in the tentwith the predictionsof Dozierand Tappert [J. Acoust.Soe. Am. 64, deepocean only for a carefullyselected choice of experimentalparameters 533-547(1978)] who used a coupledmode model. [Work supported by (range,center frequency, and bandwidth) which may not be experimentally ON'P,and ARPA.] accessible.[Work supported by ONR.]
10:45 11:30
laAO10. Ray identificationtheory in oceanacoustic tomography. D. laAO13. Horizontal multipaths causedby mesoscalestructure and Manuary(Inst. Fiir Meereskunde,Dfisternbrooker Weg 20, D-24143Kiel, their effects on global tomographywith near-axial paths. ED. Germany) Tapper (Appl.Marine Phys., Univ. Miami, RSMAS,4600 Rickenbacker Cswy., Miami, FL 33149) and M. A. Wolfson(Penn State Univ., Theidentification problem in multipathocean acoustic tomography is UniversityPark, PA 16802) notonly one of themore crucial but also one of themore difficult signal processingproblems to solvefor further inverse studies. It isonly recently The optimisticand questionableassumption that the lowestacoustic that a tool, basedon the Bayesiandecision theory and closeto the data normalmodes are adiabatic is used.Then, for eachlow modea parabolic associationproblem in RADAR, has beenproposed by Mauuaryand wave equationin the horizontalplane is derivedthat containslateral vail- Moura.It fundamentallyuses prior informationocean variability which ability of soundspeed near the soundchannel axis causedby mesoscale transitsthrough the ray acousticmodel. It alsostatistically solves the ray structurethat is modeledby homogeneousand isotropicfluctuations hav- identificationproblem with a Bayesianstrategy. Despite the inherent com- ing a singlescale length, L•100 kin. In the geometricalacoustics limit, plexityof resultingalgorithms, a first successful attempt has been made on horizontalrays are foundto be chaoticwith the growthrate (Lyapunov a Frenchtomographic set of data(GASTOM). Some simplifications and exponent)given by v•e"2131L,where •-5x 10-3 is therms sound speed furtherexperimental use are now being investigated on the Mediteranean fluctuation.Horizontal multipaths begin at thefocal range, rf•v-•3 setof data(THETIS). With another approach given by Send,those are the Mm, and thereafterthe numberof horizontalmultipaths per mode in- only practicaltools, but, they are sufficientlygeneral to solvethe identi- creasesexponentially at the rate v until diffractioneffects limit thisray ficationproblem in the mostdifficult conditions given by unresolvedand chaos. Full saturation is found to occur at the "log range," unstabledata. Both solutionsare very closeto the generalizedKalman rs•rf ln(L2/hrl)•14Mm, for the acoustic wavelength h-30 m.Since filter theoryand joint useof thesealgorithms in dataassimilation models modecoupling is neglected,this saturation range is a hardupper bound for can be expected. doingglobal ocean acoustic tomography with near-axial paths. [Work sup- portedby ONR andARPA.]
11:00
laAOll. Frequencyinterpolation method for increasingspeed of 11:45 long-range broadband parabolic equation (PE) calculation,K. D. Heaneyand W. A. Kuperman(Marine Phys.Lab., ScrippsInst. of laAO14. Travel time effectsof mesoscalestructure on rays and Oceanog.,La Jolla,CA 92093-0238) wavesat globalranges. F. D Tappertand Xin Tang (Appl.Marine Phys., Univ. Miami, RSMAS, 4600 RickenbackerCswy., Miami, FL 33149) An interpolationmethod that increases the speedof broadbandrange- dependentcalculations by anorder of magnitudeusing the parabolic equa- A range-dependentray tracemodel and a broadbandPE modelare used tionhas been developed. By decomposingthe verticalfield into complex to modelsound propagation at fixedbearing through a field of mesoscale modalamplitudes, interpolation across frequency is possible.The method baroclinicmodes in order to studythe effectsof mesoscalestructure on was designedto be usedin Monte-Carlo studiesof the effectsof internal traveltime at longranges. The ray modelexhibits chaos at rangesbeyond waves.Signal processingalgorithms are being developedto extractthe a few Mm as manifestedby an exponentiallyincreasing number of eigen- deterministicsignal from the internal wave noise.The method has been rays and triplications,especially in the late-time near-axial arrivals. In benchmarkedagainst the fully broadbandPE for severalocean environ- addition,the ray modelpredicts a mesoscaletravel time bias,in the direc- ments.The resultsare in goodagreement with the PE for 1000-kinpropa- tion of later time, of the last axial arrival amountingto about 100-200 gationthrough internal waves and for 3000-kmmildly varyingocean en- ms/Mm. At centerfrequency 75 Hz and bandwidth50 Hz, the full-wave vironments.The reproductionof the internalwave effects in the SLICE89 PE model qualitativelyconfirms the ray trace predictionsof chaos,and experimentreported by Colosi[Colosi et at., J. Acoust.Soc. Am. 96, shows that the later near-axial amvals are smeared out into a continuum of 452-68 (1994)] hasalso been possible. Frequency interpolation predic- unresolvablemultipaths characterized by saturated(Gaussian) statistics at tionsof the ATOC AcousticEngineering Test will be presentedand com- rangesof a few Mm, andalso quantitatively confirms the mesoscale bias of paredwith preliminaryresults from the experiment.In particular,simula- 100-200 ms/Mm of the lastaxial arrival.The steeper,early raylike arrivals tion of the statistics of the internal wave effects as measured in the are relativelystable in the presenceof mesoscalestructure and may be AcousticEngineering Test is of main concern. usefulfor long-rangetomogmphy. [Work supported by ONR.]
3235 J. Acoust. Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3235
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp TUESDAY MORNING, 30 MAY 1995 RENAISSANCE WEST B, 8:30 TO 11:30 A.M.
Session laBV
Bioresponseto Vibration and to Ultrasound:Progress in Vibrotaction:From Periphery to Cognition
Ronald T. Verrillo, Chair Institutefor SensoryResearch, Syracuse University, Merrill Lane, Syracuse,New York13244-5290
Chair's Introduction---8:30
Invited Papers
8:35
laBV1. Biophysicalproperties of a tactilemechanoreceptor: The Paciniancorpuscle. B. W. Pietrasand S. J. Bolanowski(Dept. of Bioeng.and Neurosci., Inst. for SensoryRes., Syracuse Univ., Syracuse, NY 13244) The Paciniancorpuscle is a tactilemechanoreceptor composed of a neuralelement surrounded by a multilayered,fluid-filled accessorycapsule. Receptor potentials recorded from isolatedPacinian corpuscles in responseto sinusoidalvibrations have nonlinear, asymmetricfull-wave rectified transfer functions. The frequency response is U-shapedwith a bestfrequency near 300 Hz. ThePacinian corpuscle'saccessory capsule was studiedexperimentally and modeledtheoretically to determineits mechanicalcontribution to the observedphysiological response. Measurements of reactiveforce in responseto sinusoidalcompression showed that the reactive force is linear, and increaseswith frequencyand amplitude.The compressiveforce can be describedby a first-orderlinear differential equationof the formf(x,t)= kx + cdx/dt. Interlamellarfluid velocitiesand lamellardisplacements were alsocomputed for a rangeof frequencies.Computational simulations of the interlamellarfluid flow in responseto sinusoidaldisplacement of the surfaceof the capsuleshows that the multilayeredstructure lineadzes the interlamellar fluid velocity, thereby linearizing the interlamellar compres- sive force.Thus both the mechanicalfiltering by the accessorycapsule and the electrodynamicalproperties of the neuritecontribute to the nonlinear,physiological response profiles seen in the receptorpotential. [Work supported by NSF, IBN-9211561.]
9:05
laBV2. Tactile perceptionwith haptic displays.Janet M. Weisenberger(Dept. of Speechand Hear. Sci., Ohio StateUniv., Columbus,OH 43210)
Tactilesensing of objectsand surfacesis typicallyaccomplished via movementof the handor fingersrelative to the objectbeing sensed,a modeknown as haptictouch. Despite this fact, mostprevious work on the tactileresponse to complexvibratory stimuli has employedstationary displays. Although pattern movement can be simulatedon thesedisplays, kinesthetic feedback from active movementof the handis absent.The presentpaper describes a seriesof studiesemploying a hapticvibratory display for the index fingertipthat can be movedacross a surfaceto encounterand scan virtual stimuli, thus preserving kinesthetic feedback. Experiments comparingthis haptic scanning mode to stationarydisplay modes showed a significantsuperiority of hapticscanning. However, most of this advantagewas attributableto the ability to scanpatterns repeatedly and from multipledirections, and not to hapticsper se. Furtherexperiments examined whether reductions in the display'sfield of view couldbe compensatedby hapticscanning. Dramatic reductionsin the field of view showedminimal decreases in performancewhen haptic scanning was employed. Results are discussed in termsof therole of hapticsin tactilesensing and implications for thedevelopment of tactiledisplays. [Work supported by Systems ResearchLaboratories and ASFOSR.]
9:35-9:45 Break
9:45
IaBV3. Cortical plasticityand representationof spatiallytemporally distributed tactile stimuli. XiaoqinWang and Michael M. M•rzenich (ColemanLab. and Ke•k Ctr. for Int•grativcNcuro•ci., Univ. of Callfomia at San Franciaco,P.O. Box 0732, San Francisco,CA 94143-0732)
An importantproperty of the cerebralcortex is its ability to reorganizeitself in responseto changingsensory environment throughoutlife. Representational"maps" of skinsurfaces in theprimary somatosensory cortex (SI) areremodeled after many forms of inputalteration. Two questionswere addressedin our recentplasticity experiment: Under what specificconditions are spatially distributedand time-varying sensory inputs (a) integrated,or (b) segregatedin theirrepresentations by the dynamicmechanisms underlyingcortical function? The resultsshowed that the topographicmap of skinsurfaces in SI wasdramatically remodeled in adult owl monkeystrained to discriminatetwo tactilestimuli applied to distaland proximalsegments of their fingersin alternation. Subsequentmapping of area3b revealedneural responses with eitherdistal or proximalmultiple-digit receptive fields, reflecting corticalintegration of inputsfrom temporally coincidentally excited skin surfaces. By contrast,the cortical representations of tempo- rallynoncoincidentally stimulated skin surfaces were segregated from each other. These findings directly demonstrate that for learning inducedplastic changes in corticaltopographic maps, afferent input integration and segregation are dependent on stimulus coincidence, andthat regularly practiced hand use results in a representationof its sensorysurfaces in thebrain that reflects that specific use.
3236 d. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3236
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 10:15
IaBV4.Influences of painand learning on vibrotaction.Stanley J. Bolanowski,Lisa M. Maxfield,Karen L. Hall,and •Iames C. Makous(Dept. of Bioeng.and Neurosci., Inst. for SensoryRes., Syracuse Univ., Syracuse, NY 13244) Theparallel processing of tactile information by independentchannels as defined psychophysically, physiologically and anatomi- callyhas been amply described in the literature. For a unifiedpercept to occur, however, information carried by these separate channels mustbe combined centrally. Furthermore, the unified percepts are affected by submodality interactions, such as the gate theory of pain wherebytactile stimulation suppresses pain, and cognitive factors (e.g., attention). Several series of experimentsarepresented showing thatpainfully hot and cold stimuli can substantially diminish vibrotactile sensation, but only when co-locafized with the tactile stimuli. Theeffect occurs regardless of thetactile channel activated. This tough-gate acts oppositely to thepain gate and indicates centrally locatedtouch-pain interactions. The results of additionalexperiments show that training of observersin anintensity-discrimination taskcan significantly affect the ability to distinguish differences in vibrotactile intensity. This learning effect appears to bebilateral and affectsintensity as well as spatio-temporal perceptions of tactile stimuli. The effect indicates that high-level cognitive functions can influencetactile perceptions; the neural basis for theseperceptions are presumably located at theconical level.
ContributedPapers
10:45 intensityand duration of themasking stimulus were similar for boththe P laBVS. Changesin mechanoreceptor-specificvibrotactile thresholds and NPI channelsas indicatedby the nearlyidentical results measured at 250 and 20 Hz. The observed declines in threshold as a function of At and with ongoingoccupational exposure to hand-transmittedvibration. A..I. Btammetand •I. E. Piercy(Inst. for Microstruct.Sci., Natl. Res. signalduration were both attributedto an increasein the time interval CouncilCanada, Ottawa, ON Canada),S. Nohara (Asahi Mutual Life betweenthe offset of themasking stimulus and the offset of thesignal. InsuranceCo., Fukui, Japan),and H. Nakamura(Tokushima Univ., Tokushima,Japan)
The purposeof thispaper is to explorethe influence of occupational exposureto hand-transmittedvibration on mechanoreceptoracuity, for possiblefuture use as a screeningtest for earlysymptoms of thehand-arm vibrationsyndrome (HAVS). Mechanoreceptor-specificvibrntactile thresh- 11:15 oldswere determined using the tactometer at frequenciesmediated by the SAI receptors(4 Hz), FAI receptors(32 Hz), andFAII receptors(100 Hz) laBV7. Nonauditory effects of waterborne sound: Subjective [A. J. Brainmetand J. E. Piercy,"Measuring vibrotactile perception responsesduring under water hearing conservationstudies. C. C. thresholdsat the fingertipsof power-tooloperators," Proc. U.K. Informal Steevensand P. F. Smith (Naval SubmarineMed. Res. Lab., Groton, CT GroupMeeting on HumanResponse to Vibration,Buxton (1991)]. Thresh- 06249) olds were obtainedfrom 33 seasonaloperators of chainsaws and brush cutters,who had so worked for upto 39 years.Twenty-three of theworkers Divershave reported that intense waterborne sound can be felt as well werejudged clinically to sufferfrom mild to moderatesymptoms of as heard.Subjective reports of nonauditorysensations were obtained from HAVS.A progressivereduction in acuitywith increasing years of exposure wasobserved, on average,in thisgroup, for eachmechanoreceptor popu- 19 divers during recentunderwater hearing conservation studies. The lation.A reductionin acuityremained even after correcting for changesin diverswere interviewedfollowing each noise exposure trial. The water- thresholdwith age. borneexposure stimuli were warble tones (_+5% center frequency) at cen- ter frequenciesvarying from 125 to 6000 Hz at sound-pressurelevels as 11:00 highas 145 dB re: 20/•Pa. Exposuredurations ranged from 43 s-15 min laBV6. The effects of the intensity and duration of a masking per exposure.Reports of direct effectson divers' bodies,and effectson stimulus,At, and signalduration on vibrotactileforward masking. diverequipment were solicited. Nonauditory sensations were reported for GeorgeA. Gescheider(Dept. of Psych.,Hamilton College, Clinton, NY frequenciesof 1000Hz andbelow, but none was reported above 1000 Hz. 13323 and Inst. for SensoryRes., SyracuseUniv., Syracuse,NY The lowerthe frequency,the lowerthe thresholdfor nonauditorysensa- 13244-5290),Kristine Santoro (Hamilton College, Clinton, NY 13323), tions.At 125 Hz, sensationswere first reporxedat a level of 104 dB re: 20 JamesC. Malcous,and Stanley J. Bolanowski(Syracuse Univ., Syracuse, /•Pa. Nonauditorysensations reported were primarily vibrationsfelt at NY 13244-5290) various locations on the divers' bodies. Anatomical localization of sensa-
Vihrotactile thresholds were found to increase as a function of the tionsvaried with frequency,but were not exclusivelyrelated to gas filled durationand intensityof a forward maskingstimulus and to decreaseas a viscera.There were alsoseveral reports of minor effectson divingequip- functionof thetime interval between the termination of themasking stimu- ment.No evidencefor nonauditory,physiological h•ard was foundduring lus andthe onsetof the signal(At) andsignal duration. The effectsof the theselimited exposures. [Work supportedby U.S. Navy.]
3237 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3237
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp TUESDAY MORNING, 30 MAY 1995 RENAISSANCE EAST, 8:30 TO 11:35 A.M.
Session laPA
PhysicalAcoustics: Scattering and Propagation
Guillermo C. Gaunaurd, Chair Naval SurfaceWarfare Center, Code 684, WhiteOak, SilverSpring, Maryland 20903-5640
Chair's Introduction--8:30
ContributedPapers
8:35 of the clutter.Statistical measures pertaining to the clutterare given con- sideration,as is the effectof systemnoise added to the data.Results are laPAL On local versusglobal parametrization of short-pulse-excited presentedand discussed. [Work supported by ONRand AFOSR.] scatteringand spectra:Poisson summation revisited. LeopoldB. Felsen (Dept. of Aerospaceand Mech. Eng., BostonUniv., 110 CummingtonSt., Boston,MA 02215)
Poissonsummation has conventionallybeen employedfor conversion of local scatteringsdue to individualelements in an infiniteperiodic array 9:05 intoglobal Bragg spectra that characterize the collective phenomena due to laPA3. Acoustic response of interacting gas bubbles. Daniel the entire array. In a recentgeneralization, time harmonicand transient Goldman,Paul E. Barbone,and Ali Nadim (Dept. of Aerospaceand local-globalphenomena in finite periodicand quasiperiodicarrays have Mech.Eng., Boston Univ., 110Cummington St., Boston,MA 02215) beenrelated via finite Poissonsummation, with the globaloutcome inter- pretedas radiationfrom equivalent sources distributed over the finitearray aperture[L. B. Felsenand L. Carin,J. Acoust.Soc. Am. 95, 638-649 Following a method similar to that used to obtain the standard (1994)].This analysis is nowre-examined in thecontext of multiplescatter Rayleigh-Plessetequation, equations are deriveddescribing the volume scenariosunder short-pulse time-domain excitation. Since shortenough oscillationsof two interactingspherical bubbles, whose centers are as- pulsedincident fields can time-gateindividual scattered field arrivals,the sumedto be a large distance(relative to the equilibriumradii of the earlytime responseat the observeris necessarilyparametrized locally. As bubbles)apart in an infinitefluid. Although the bubblesare initiallyas- multipleinteraction develops, one may reparametrizeany finite numberof sumedto be fixed, these approximateequations also describethe move- these collectively in terms of spectraassociated with equivalentsources ment of the bubblecenters. First, the naturalfrequencies of the two-bubble that aresmoothly distributed over the correspondingmultipass finite space- system are obtained via linearization.Then, for bubbleswith the same time aperture.This resultsin globalalgorithms based partly in the con- equilibriumradii, the nonlinearstability of the symmetricand antisymmet- figurationdomain and partly in the spectraldomain. These concepts are ric modesis studiedboth analytically and numerically.The responseof the developedand examined rigorously and asymptotically with respectto the two-bubblesystem to a time-periodicpressure field is alsostudied. Finally, time evolutionof globalspectra from highlyresolved early scattersunder the equationsfor the two-bubblesystem are generalized to thosedescribing short-pulsetime-domain conditions.Corresponding statistical aspects, an n-bubble system,and an estimateis obtainedfor the lowest resonant when the scatteringhierarchy is randomlyperturbed, are exploredas well. frequencyof the n-bubblecloud. [Worksupported by AFOSRand ONR.]
8:50
9:20 laPA2. Short pulse sound wave scattering by a fluid shell model target near a randomly distorted bottom interface: Wave oriented IaPA4. Scattering from a fluid-loaded elastic spherical shell in data processingfor target-clutter discrimination. T.T. Hsu, L. Carin proximity to a rough fluid-elastic interface: Numerical results. (Dept. of Elec. Eng., PolytechnicUniv., Six MetrotechCenter, Brooklyn, Judy Smith and Gamer C. Bishop (Nav. UnderseaWarfare Ctr. Div., NY 11201), and L.B. Felsen (BostonUniv., Boston,MA 02215) Newport,RI 02841-5047) A finite differencetime-domain (FDTD) code has been usedto as- semblea comprehensivedata baseof realizationsfor short-pulseplane A null field T-matrix formalismis developedand usedto calculate wave scatteringby a fluid shellmodel target submerged in the presenceof scatteringof a pressurewave from a fluid-loadedelastic spherical shell in a randomlydistorted bottom interface. The entireproblem is two dimen- proximityto a roughfluid-elastic interface. The Helmholtz-Kirchhoff sionalwith the scatteredacoustic pressure observed along an elevatedtrack integralrepresentations of the variousscattered pressure and displacement above the target and parallel to the mean bottom boundary.Two bottom fieldsare constructed.The surfacefields are requiredto satisfythe elastic topographiesare examined: (1) a smoothlydeformed interface between the boundaryconditions and the scatteredfields are requiredto satisfythe water columnand a fluidbottom; (2) a collectionof softrandomly pitched extendedboundary condition. The free-field T matricesfor the elasticshell thin fiat strips.The databasefurrushed by the ensembleof realizationsfor and the rough fluid-elastic interface are constructedand used in the the randomly irregular bottom, in which the deterministictarget remains Helmholtz-Kirchhoff and the null field equationsfor the shell-interface unchanged,is subjectedto wave-orienteddata processing that yields space- system.It is shownthat the T matrixfor thesystem is simplyrelated to the wave numberand time-frequencyphase space distributions extracted via free-fieldT matricesfor the shelland the roughfluid-elastic interface. A windowedtransforms and refinedby locally appliedhigh resolutionalgo- perturbativesolution is obtainedfor scatteringfrom arbitraryroughness, rithms.The processingis appliedto the targetalone, the clusteralone, and andan "exact"solution is obtainedfor scatteringfrom periodic roughness. the target-cluttercombination. Target resonances are regardedas a major The "exact" solutionis usedto obtaina varietyof numericalresults that discriminantwhich one needsto enhanceby input signalshaping and showsome of the effectsof the acousticcoupling that occursbetween the outputfilmting while simultaneouslyde-emphasizing the cormptingeffect roughinterface and the elasticspherical shell.
3238 d. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3238
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 9:35 phonemay be on the oppositeside of the sheet.The understandingand controlof the spectrumof the radiatedpressure pulse is usefulfor facili- IaPA$. The effect of turbulencedrlf! on acoust'calscattering into a tatingthe detectionof specifictarget spectral features. An idealizedcircuit shadowregion. MichaelR. Stixson (last. for Microstruct.Sci., Natl. model is examinedwhere the sheetis excitedby a step voltagesource Res. Council, Ottawa, ON K1A 0R6, Canada} havinga real impedancegiven by the resistanceR. Let C denotethe sheet The turbulencestructures responsible for acousticalscattering in the capacitanceand let the stepocctlr at t=O. The radiatedpressure for a thin atmosphereare not staticand evolve in time. As a first approximation,a she•,tbecomes a step followed by anexponential tail: exp(-tlRC). The uniformdrift of lbe turbulencewith the prevailingwinds, consistent with magnitudespectrum is proportional to [I+(•oRC} 2]-•a. Increasing R re- Taylor'shypothesis, can be anticipated.This drift can be accommodated ducesthe high-frequencycontent which may be advantageousfor certain throughan extensionof the Green'sfunction parabolic equation (GF-PE} measurements.Applications include the impulse excitation of low- approach.Normal implementations of the GF-PE computethe soundfield frequencystructural resonances of shellsin water.Adjacent modes exhibit assuminga staticrealization of turbulence.Such calculations can be re- a prominentbeating in the response.[Work supported by the Officeof peated,though, for successiverealizations of a turbulentatmosphere, with NavalResearch.] eachrealization corresponding to an additionalshift in spaceof the initial turbulentstructure. The resultingseries of soundfield "snapshots"shows the evolution of the sound field as the turbulence drifts. Recent simulations usingthe GF-PE haveexamined scattering by driftingturbulence into an acousticalshadow, formed during upward refracting conditions, and the 10:35 time evolutionof the scatteredfield will be presented.The natureof these timevariations isrelevant totl•e use of beamforming arrays inan acoustic IaPA8. Sound diffraction by a ground with barriers or impedance shadow.Some observations about predicted array responses will be dis- discontinuitiesin a refracting atmosphere. Y. L. Li (Wave cussed. PropagationLab., Dept. of Elec. and Cornput.Eng., Univ. of Illinois at Urbana-Champaign,332 CSRL, 1308W. Main Street,Urbana, IL 61801)
9:50 and Michael J. White (U.S. Army ConstructionEng. Res. Lab., Champaign,IL 61826-9005) laPA6. Resonantbehavior of two eclipsedshells: Quasiharmonic study. P. Pareige,Elm. Kheddioui,J. M. Conoir,and J. L. Izbicki (Lab. The exact solution for the total field is obtained for the sound diffrac- d'Acoust. Ultrason. et d'Electron., U.R.A.C.N.R.S. 1373, Univ. du Havre, tion due to a time-harmonicline sourceabove a groundin a mediumwith placeRobert Schuman, 76 610 Le Havre,France) linear sound-speedprofile. The groundmay have barrierswith arbitrary The purposeof this paperis the presentationof temporal,frequeotial, shapesor impedancediscontinuities parallel to the line source.The solu- andangular experimental studies of the acousticscattering by two identical tion is in termsof an integralequation which is numericallysolved by an air-filledelastic shells immersed in water.They are insonifiedby a quasi- extensionof the methodof moments.The effectsof scatteringin the region harmonic wave at normal incidence. The distance between the shells is aroundbarriers or impedancediscontinuities are studiedfor situationsfor about I to 3 diametersof one shell.The frequencyrange investigated variousvalues of the refractingstrength of the sound-speedprofile. correspondsto the whispering gallery wave resonances (/=2). The con- figurationconsidered is the eclipsedone: Emitter and shellsare on the sameaxis. The complexstructure of the backscatteredtemporal signal is analyzedand theoretically justified. According to thepart of thetemporal signalconsidered, different backscattering spectra are obtainedand ana- 10:50 lyzed.The resultsare discussedin termof acousticrays involving internal IaPA9. Application of the PE method to up-slope sound andexternal acoustic waves. In addition,a phenomenonof acousticinter- propagation. MartaGalindo and Karsten Bo Rasmussen(Aeoust. Lab., ferenceis clearly shown.AI the resonancefrequencies of one shell, the Bldg.352, Tech.Univ. of Denmark,DK 2800 Lyngby,Denmark) angulardiagram shapes are justified and compared to thoseprovided by an analytic model. In all cases,the resultsare comparedto the well-known resultsprovided by the studyof a singleshell. The wide-anglePE methodis appliedto the predictionof soundpropa- gation in a range-dependentenvironment. The finite-differencemodel treatsthe slopingground by a staircaseapproximation. The methodallows 10:05-10:20 Break impedanceand slope angle variations to be takeninto account. The imple- mentationof slopinginterfaces in one-wayPE modelsintroduces a fun- 10:20 darnextolproblem of energyconservation. This is generatedat the lower boundarycondition. The groundis assumedto be a locallyreacting surface IaPA7, Pressure impulse response measurements for elastic where the groundimpedance is definedas the ratio of pressureto the scatterersin water and regulation of the sourcespectrum. Philip L. normalcomponent of particlevelocity at the surface.The staircasePE Marstonand ScottF. Morse (Dept. of Phys.,Washington State Univ., methodapproximates the normalat the slopesurface with the vertical Pullman,WA 99164-2814} componentat the stair-stepsurface. A numericalcorrection can be in- A largePVDF sheetadjacent to thescatterer has been used to excitethe cluded.Using a scalemodel facility [K. B. Rasmussen,J.Aeoust. Soc. Am. plane-wavepressure impulse response of elasticshells over a widespectral 96, 3617-3620 (1994)], a seriesof measurementsis carriedout. The re- range[Kaduchak et al., to be publishedin J. Acoust.Soc. Am. (1995)]. sultsare comparedwith the PE calculations.The magnitudeof the error Sincethe sheetis transparentto the scatteredsignal, the receiverhydro- due to the interface condition is evaluated.
3239 J. Acoust.Soc. Am., Vol.97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3239
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 11:05 Preliminaryexperiments using Styrofoam indicate that similar trendsexist above the low impedancerough surfaceas did over the high impedance IaPAIO. An experimental investigationof the propagation of sound roughsurfaces. [Work supported by USDA.] over a fiat rough surface of finite impedance. J0•nesP. Chambers andJames M. Sabafier (Natl. Ctr. for Phys.Acoust., Univ. of Mississippi, University,MS 38677) 11:20
Recentwork on rough surfaces byMedwin et al. [J. Acoust. 'Soc. Am. laPAll. Locally reacting boundary condition over sloping 79, 657-665 (1986)]has indicated the presenceof acousticboundary boundaries for the parabolic equation. B. G. Tollison, J. S. wavesin the fluid directlyabove rough surfaces with highacoustic imped- Robertson(Dept. of Math. Sci., U.S. MilitaryAcademy, West Point, NY ances.The effectof this boundarywave is that the soundfield abovethe 10996-1786),and W.L. Siegmann(Rensselaer Polytech. Inst., Troy, NY roughsurface is louderthan it wouldhave been over a similarlysmooth 12180-3590) surfaceat closeranges due to multiplecoherent scattering. The oppositeis true at longerranges since the scatteringbecomes incoherent. The ranges A boundarycondition which modelslocally reactingboundaries is of coherentand incoherentscattering depend on the roughnessscale and derivedfor thegeneralized parabolic equation: This formulation is valid frequencyof the soundsource. The experimentalwork describedabove over nonhorizontalboundary surfaces. The deri9edcondition is discretized wasperformed over surfaceswith high acousticimpedances such as wax usingLagrange polynomials. Particular implementation schemes are dis- andsteel. The purposeof thispresent work is to findout if similartrends cussedfor nonhorizontalboundaries. Numerical results compare the accu- existin thepropagation of soundover rough surfaces that possess a lower racy of this approachwith other methodsthat have been usedwith the PE. acousticimpedance. Sound signals will be measuredabove a roughsurface Comparisonwith experimental results may also be presented.[Work sup- andcompared to the signalabove a smoothsurface of the samematerial. portedby ONR andUSACECOM.]
TUESDAY MORNING, 30 MAY 1995 CONGRESSIONAL HALL B, 8:30 A.M. TO 12:00 NOON
Session IaSC
SpeechCommunication: Speech Processing and Perception/Psychophysics(Poster Session)
W. Van Summers, Chair WalterReed Army Medical Center,Research Section, Army Audiologyand SpeechCenter, Washington, DC 20307
ContributedPapers
All posterswill be on displayfrom 8:30 a.m. to 12:00 noon.To allow contributorsan opportunityto seeother posters, contributors of odd-numberedpapers will be at theirposters from 8:30 to 10:15a.m. andcontributors of even-numberedpapers will be at theirposters from 10:15 a.m. to 12:00 noon.To allow for extendedviewing time, posterswill remain on display until 8:00 p.m.
IaSCI. The effects of talker variability across CV and VC laughing/pleased/happy,shout/surprising versus secret-talk/calm,and environments. Lynn M. Farnsworthand JohnW. Mullennix (Dept. of speakingversus singing were studied. Even at 2 monthsof age,significant Psych.,Wayne State Univ., 71 W. WarrenSt., Detroit,MI 48202) individual differences were observed in the extracted factor scores, al- thoughthree were less variability comparedto thoseobtained from the A consonantalspeeded classification task was used to assessthe effects elderinfants' vocalizations. These results suggest that the ability to express of talker variabilityacross CV and VC environments.In addition,condi- emotionthrough vocalization seems to be developingduring the observed tionswere blocked by syllabletype (CV or VC) or consistedof mixedsets monthsof age,although infants even at 2 monthsof agecan express some of CV and VC syllables.Talker variabilitywas manipulatedby presenting aspectsof emotionthrough vocalization. stimuli spokenby a singletalker or by many talkers.The resultsshowed that the magnitudeof the effectof talker variabilitywas approximatelythe laSC3. A longitudinal investigation of children's duration and samewhen comparingperformance across talker contextsfor CV's and temporal variability in speechproduction. Bruce L. Smith, Mary VC's. In addition,the talker variability effect was strongerunder condi- Kay Kennedy,and Satmad Hussaln (Dept.of Commun.Sci. and Disoral., tionswhere syllables were blocked. The resultsprovide further information NorthwesternUniv., 2299 North CampusDr., Evanston,IL 60208-3570) aboutthe underlyingmechanisms involved in processingpemeptual varia- tion in the speech sil•nal. A number of cross-sectional studies have observed that children's speechsegments tend to decreasein duration and also becomeless variable from youngerto older groupsof subjects.Because cross-sectional inves-..:. , laSC2. Adult attribution of the intent vocalizations. Yoko Shimura tigationshave certainlimitations when they are usedto studychildren's (Dept. of Educ.,Saitama Univ., 255 Shimo-Okubo,Urawa-shi, Saitama, development,it is also importantto conductlongitudinal analyses of 338 Japan) and SatoshiImaizumi (Univ. of Tokyo, 7-3-1 Hongo, speechproduction development. The presentstudy provides data basedon Bunkyo-ku,Tokyo, 113 Japan) a longitudinalanalysis of the speechof 12 children.When they were initially seen, the children ranged from 7-11 years of age; they were Adult attributionof the infant vocalizationswas investigatedby per- evaluatedagain after approximately 1-1/2 years.At bothages, the children ceptualrating experimentsfor 717 voice samplesrecorded from seven were recordedas they produced25 repetitionsof eachof severaldifferent infantsat 2, 6, 9, 12, and 17 monthsof age. Perceptualrating was per- wordsand short phrases, from whichvarious segments and syllables were formed usingnine vocalization-and emotion-relatedreference words by measured.Results indicate that, on average,segment and syllabledura- 15 normal heating adult listeners.By a principal factor analysis,three tionsdecreased from the initial to the follow-uprecordings by approxi- factorsrepresenting the emotionalcontrast of crying/frightened/sadversus mately10%, whereastemporal variability was found to decreaseby about
3240 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3240
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 40%. Althoughthe relativedecrease in the children'stemporal variability respondedto the loudnessof eachof ninesuprathreshold intensity levels of was substantiallygreater than the decreasein their duration acrossthe an Englishsentence. For the secondtask, subjectsin both groupswere year-and-a-halftime period,their durations were considerably more adult- instructedto assigna numericalvalue that corresponded to the loudnessof like thantheir variabilityat both timesthey were studied. eachof nine suprathresholdintensity levels of the samesentence spoken in Hindi. Statisticalanalysis showed no significantdifference between the IASC4. Speech during simultaneous communication: Temporal two groups in the scaling of the English and Hindi sentences.Results characteristics and perceived naturalness. Robert L. Whitehead suggestedthat magnitude-estimationscaling appears to be an effective (Comm. Res. Natl. Tech. Inst. for the Deaf, 52 Lomb Memorial Dr., measureof loudnessof familiar and unfamiliarlanguages, and that sub- Rochester,NY 14623-5604), Nicholas Schiavetti (State Univ. of New jects scalethe loudnessof a familiar languagethe sameway as they scale York, Geneseo,NY 14454), BrendaH. Whitehead (Natl. Tech. Inst. for the loudnessof an unfamiliarlanguage. the Deaf, Rochester,NY 14623),and Dale Even Metz (StateUniv. of New York, Geneseo,NY 14454) laSC7. Talker-basedselective adaptation. Gary E. Starrand Mark A. Pitt (Dept.of Psych.,Ohio State Univ., 1885Nell Ave.,Columbus, OH Simultaneouscommunication is a processwhich combines spoken En- 43210-1222) glishwith variousmanual representations of Englishwords in the form of signsand fingerspelling.The presentstudy investigatedthe durational Whenduring perception does the auditorysystem differentially process characteristicsand perceived naturalness of speechproduced during simul- certainclasses of soundobjects? For example,in somemodels of speech taneouscommunication with increasingfingerspelling complexity. Ten perception,only phoneticstimuli are processedin the highestlevels of normal-hearingadult females,skilled in the use of simultaneouscommu- analysis.Prior work in this lab [M. A. Pitt, J. Acoust.Soc. Am. 95, nication,served as speakers.Experimental words of differing finger- 2975(A)(1994)] found that stimuli varying in musicaltimbre yielded se- spellingcomplexity were embedded in sentenceswhich were: (a) spoken lectiveadaptation results qualitatively similar to thoseobtained with pho- and(b) spokenand signed, except for theexperimental words which were netic stimuli.The generalityof this finding was assessedby conducting fingerspelled.Five temporalmeasures of speechwere calculated: (a) sen- comparableexperiments ona nonphoneticdimension that originates from tenceduration, (b) experimentalword duration,(c) diphthongduration the same sourceas a phoneticpercept: talker identity.Two selectivead- precedingthe expe.dmental word, (d) pauseduration preceding the experi- aptationexperiments were conductedusing a voice continuum.Talkers mentalword; and (c) pauseduration following the experimentalword. spokethe samevowel. Endpointadaptors and different-voweladaptors Speechnaturalhess was rated using a nine-pointnaturalhess rating scale for were presentedipsilateral and contralateralto the ear of identification. all stimulussamples. Results indicated significant differences in durational Resultsare similar to prior findings,and suggestthat theseclasses of measuresand naturalhessratings between the speech-onlyand simulta- objectsare processedsimilarly to a fairly abstractlevel of analysis.[Re- neouscommunication conditions, and betweenlevels of fingerspelling searchsupported by NIH.] complexity.A multipleregression analysis was performedto predict speechnaturalness from the durational measures used as independent vari- laSC8. The effects of talker-specificinformation on immediate ables.The multiple R2 was 0.698. [Work supported byU.S. Department of memoryspan. HelenaM. Salda•a (SpeechRes. Lab., Dept. of Psych., Education.] IndianaUniv., Bloomington,IN 47405)
laSCS. Speakernormalization for tone. CorinneB. Moore (Dept.of Recentevidence suggests that talker-specificinformation is retained Mod. Lang. and Lit., 203 Morrill Hall, CornellUniv., Ithaca,NY 14853) alongwith codesfor wordsand phoneroes in long-termmemory [Palmeri et el., JEP:LMC 19, 309-328 (1993); J. W. Mullenix and D. B. Pisoni,J. Segmentswith identicalacoustic characteristics may not be perceived Acoust.Soc. Am. 85, 365-378 (1990)]. If this indexicalinformation is identically,because listeners normalize for acousticvariability due to vocal retained,one wouldexpect talker-specific information to alsoeffect a lis- tract differencesamong speakers. While normalizationstudies have been tener'sperformance on short-termmemory tasks. However, the predomi- donefor vowelperception, the presentexperiment uses Mandarin Chinese nant trace decay theoriesof short-termmemory do not predict this. For to investigatespeaker normalization for lexical tones.In this study,two example,in the articulatoryloop model, itemsare storedas memorytraces speakerswere identifiedfor whom the low tone (tone 3) of the high- that fade after approximately2 s unlessrevived by an articulatorycontrol pitchedspeaker occurred in the sameF0 regionas the midrisingtone (tone process[A.D. Baddeleyand G. J. Hitch, Psych.Learn. Motiv. (1974)]. 2) of the low-pitchedspeaker. Synthetic syllables formed three continua The numberof itemsthat can be reactivatedwithin the decaytime can be usedin a seriesof perceptiontests. The threecontinua varied along either retainedindefinitely. Therefore, immediate memory span is definedin F0, timingof the turningpoint, or bothacoustic dimensions. Stimuli were termsof time or durationof items.In the presentinvestigation, memory placedafter a naturalprecursor from eachof the two speakers.Test items spanexperiments were conductedin which voice informationwas held wererandomized and presented in a mixedblock condition. Results show constantor waschanged for eachitem in the list.Initial resultsindicate that thatcategory boundaries shift contrastivelyin the directionpredicted; that a changein voice informationresults in a decreasein memory span. is, the samestimuli were perceived differently in the two precursorcon- Follow-upexperiments manipulate speaking rate and presentation level. A ditions,although only for stimulivarying along the F0 and both F0 and recoBceptualizationof the articulatoryloop modelis discussedwhich takes turningpoint dimension,but not for stimuli varying along the duration into accountthe encodingof stimulusvariability. [Work supportedby dimension(turning point) alone.Further testing is currentlybeing con- NIH.] ductedon normalizationin the durationdimension. [Work supported bY SigmaXi.] laSC9. The role of experience in the development of category structures. BarbaraE. Acker and RichardE. Pastore (Dept. of Psych., laSC6. The effect of stimulus familiarity on magnitude-estimation SUNY Binghamton,Binghamton, NY 13902) scaling of different languages. Donald Fucci (School of Hear. & Speech Sci., Lindley Hall 219, Ohio Univ., Athens, OH 45701), Recentspeech research and music work havefound empirical evidence RameshBettagere, Maria D. Gonzales,Mary E. Reynolds (OhioUniv., for prototypesor exemplars.Whereas the functionof a speechprototype is Athens,OH 45701), and Linda Petrosino (BowlingGreen State Univ., debatable,experiments using musically trained subjects found better dis- BowlingGreen, OH 43403) criminationaround major chord prototypesthan near lessrepresentative membersof the category.While the specificfunction of prototypesis of The purposeof this studywas to examinelistener's abilities to judge interest,the developmentof prototypesis also importantin elucidating the subjectiveparameter of loudnessof familiar and unfamiliarspoken perceptualprocesses. Developmental processes in speechand musichave languages.Two groups o[ subjects consisting of 20 adults each, ranging in been studied by comparing infant and adult data. Utilizing musically nmve age from 20-32 years,participated. Group 1 consistedof subjectswho adultsubjects and musical stimuli, the currentwork investigatesperceptual were familiar with Englishand not familiar with Hindi. Group 2 consisted differencesattributable to training and experience,but avoids problems of subjectswho were familiarwith Englishas well as Hindi. Two separate associatedwith infant subjects.The ability of nonmusicallytrained sub- magnitude-estimationscaling tasks were performed. For the firsttask, sub- jectsto discriminatein-tune (prototype [P] set)and mistuned (nonproto- jectsin bothgroups were instructed to assigna numericalvalue that cor- type[NP] set)major chords was evaluated in anAX task.Unlike musicians
3241 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3241
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp who showedsignificantly better performance with the P set, the naive providedthe target voice was at least 5 dB louder.Hence, infantshave subjectsshowed no differencesbetween the P andNP setsof stimuli.These somecapacity to extractinformation from speecheven in the face of resultsdemonstrate the needfor experiencefor the developmentor acti- competingacoustic signals. [Work supported by NICHD to PWJ andan vationof prototypes.Whereas the music results may not provide a direct NSF GraduateFellowship to RN.] parallelto speech,they do providea basisfor comparison.[Work sup- portedby AFOSR.] laSC13. The relationshipbetween the discriminabilityof formant transitionsand certain cognitive measures. Thomas Cartell (Barkley laSC10.The effectsof feedbackin auditorylooming tasks. A. Paige Ctr.,Univ. of Nebraska,Lincoln, NE 68583-0738),Nina Kraus,Terry Wuestefeldand LawrenceD. •Rosenblum (Dept. of Psych.,Univ. of McGee,and Steven Zecker (NorthwesternUniv., Evanston, IL 60208) California, Riverside,CA, 92521) Thiswork concerns the relationship between two measures of auditory Previousresearch [Ro, senblum et al., Perception22, 1467-1482 processingand several measures of cognitiveabilities. The discriminabili- (1993)] demonstratesthat listenersare able to make somewhataccurate tiesof formanttransitions in synthesizedconsonant-vowel syllables were anticipatoryjudgments regarding the time to arrivalof a loomingsound collectedfrom over 100 childrenaged 7-11. Specifically,the discrim- sourceand that performancefeedback significantly improves these judg- inabilitiesof the F 3 onsetfrequencies were measuredin a set of stimuli ments.The presentresearch examines the effectson performanceof pro- whichranged pemeptually from/do/from/go/. Also,the discriminabilities vidingfeedback to listenersand subsequently withdrawing it. Somevisual of the onsettransition durations of F•, F 2, and F 3 were measuredin researchinvolving the extrapolationof movementsuggests that, upon stimuliwhich ranged perceptually from /bo/ to /wo/. A PEST adaptive withdrawingfeedback, performance will revertback to its originallevel. trackingparadigm was employed to makethese measurements. The aver- Subjectsmade judgments about the timeto arrivalof an approachingcar agejust noticeable difference was 101 Hz for theF 3 onsetfrequencies and basedon various portions of the event. Each subject participated in three 6 ms for the F], F2, and F 3 frequencyramps. A batteryof testsof experimentalsessions on consecutivedays. Subjectswere divided into cognitiveability were administered to the samechildren. The cognitive threegroups which received differing feedback schedules. For all groups, abilitytests revealed a wide range of scoresin thesubjects te•t•d. A thefirst session contained no Performance feedback. The withdrawal group correlationalanalysis of thesedata indicated that better onset frequency receivedfeedback during the second session, but not the third. One control discriminabilitywas significantlycorrelated with higherscores on the groupreceived no feedbackfor theremainder of theexperiment. A second reading subtests,whereas better scoreson transitionduration taskswere groupcontrol group received feedback for both the secondand third ses- not significantlycorrelated with any of the cognitiveability measures. It sions.When feedbackwas withdrawn,performance between the second wasalso found that better formant onset frequency discriminability did not and third sessionsdid not differ significantly.Thus, unlike the previous predicthigher transition duration;discriminability. Thatis, better/do/ vs visualeffects, performance didnot revert back to its original level. /go/ discriminationdid not predict better/bo/ vs /wo/ discrimination. [Worksupported by NIH.] laSCll. Age differencesin the uptake of acousticcues in spoken word recognition. RobertAllen Fox and Julie McGory (Dept. of laSC14. On the "locus equation"and its relation with the consonant SpeechHear. Sci., Ohio StateUniv., 110Pressey Hall, 1070Carmack Rd., placeof articulation.Samir Chennoukh, Rend Carrd (Sig.Dept. ENST, Columbus,OH 43210-1002) 46 Rue Barfault,75634 Paris,France), and Bjdrn Lindblom (Univ. of Stockholm,S-10691 Stockholm,Sweden) This studycompares the uptakeof acoustic-phoneticinformation dur- inglexical access in younger(20-30 years) and older (55-70 years) lis- Thespecification of the consonant place of articulationfrom the locus tenersto determineif thesegroups are equallyefficient in utilizingthe equationcoefficients [Sussman et al., J.Acoust. Soc. Am. 90, i256-1268 coarticulatoryinformation in VC transitions.Examined were placecon- (1991)]is subjectto discussiofi.For instance, Fowler [Percept. Psycho- trastsbetween stops (p/t and p/k) and fricatives (s/.• and z/3), and manner phys.55, 597-610(1994)] claims that these coefficients can vary signifi- contrastsbetween stops and nasals (b/m and d/n) using the gating paradigm cantlywithin hornorganic consonants. In order to studythe relation be- [Warrenand Marslen-Wilson, Percept. Psychophys. 41, 262-275(1987)]. tweenthese coefficients and placeof articulation,V 1CV2 utteranceswere Stimuliconsisted of 21 pairsof CVC wordsdiffering only in termsof the stimulatedusing the distinctive region model and three different instants of final consonant(e.g., pot versuspop), These words were heardin their initiatingthe second vowel: before the acoustic segment of. the consonant, naturalor cross-splicedforms in which the initial CV of one word was at the beginningof that segment,and, in the thirdcase, after it. The results appendedto theconsonant offset of its match.Gated versions of eachword showthat linear locus equations can be acceptablyfitted to thosecondi- wereconstructed on the basisof this 'isplicing"point such that the first tions,but that their coefficientsvary as a functionof the secondvowel gate includedthe initial CV up to 100 mse½before end of the vowel and onset.It was notedthat the locusequations are sensitiveto degreeof thenproceeded in 20-msincrements (gates that included portions of voice- consonant-vowelcoarticulation. Also, wheny interceptswere plotted lessstop closure providing no additionalacoustic information were elimi- againstthe associatedslopes for a givenplace and acrossthe simulated nated).Results will be discussedin termsof possibleage-related decre- timingconditions, highly linear relationships were observed. Thus the co- mentsin phoneticprocessing. [Work supportedby NIA.] efficientsof such"second-order" locus equations stay constant for a given laSC12.The cocktail party effect in infants.Peter W. Jusczykand placedespite variations in temporaland coarticulatory conditions. Hence, for naturalspeech, such "second-order" parameters might be a morestable RochelleNewman (Dept. of Psych.,SUNY at Buffalo, Buffalo,NY place correlatethan first-ordercoefficients. 14260) laSC15. Influenceof the numberof syllablesand tooroeon reaction Most researchon speech.recognition by infantsoccurs in quietlabo- time in Japanesespeech productio•n... Shinobu Masaki and Kiyoshi ratoryrooms with no outsidedistractions. But the real world may not Honda (ATR Human InformationProcess. Res. Labs., 2-2 Hikaridai resemblethe laboratory:Much speechdirected to infantsocturn with ½om 3eika-cho, 3oraku-gun, Kyoto, 619-02 Japan) petingacoustic signals. To learnlanguage, infants need to followtheir care-givers'speech even under less than ideal listening conditions. Infants' In orderto estimatethe processing unit of Japanesespeech production, abilitiesto followa femalespeaker's voice when a malevoice was talking theinfluence of thenumber of syllablesand morae on reactiontime (RT) simultaneouslywere examined. In pilotstudies, infants presented with two in speechproduction was analyzed. In experiment1, RT wasmeasured for competingstreams of fluentspeech showed no evidenceof recognizing one-to four-mornnonwords consisting only of JapaneseCV syllables[ka] wordsspoken by the targetvoice. In the presentstudy, infants heard a or[to]. Five subjects produced stimulus words as soon as possible after the targetvoice repeating isolated words, while the secondvoice spoke flu- visualonset signal was presented. RT wasdefined as the durationfrom the entlyat eitherof threedifferent loudness levels. Subsequently, infants momentof onsetsignal presentation to the release of word-initialplosive heardpassages produced by the targetvoice usingeither the familiar consonant.Results showed a tendencyfor RT to increaseas the numberof words,or novel words.Infants listened longer to the familiar wordswhen CV syllablesincreases. In experiment2, stimuluswords consisted of CV the target voice was 10 or 5 dB louder, but not when the distractorwas syllablesand vowels without a syllable-initialconsonant, or CV syllables equally loud. This suggeststhat infantscould separatethe two voices, andnasal sounds [N] withouta syllable-finalvowel. Note that, in Japanese,
3242 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3242
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp a voweland nasal sound [N] canbe amoralike a CV syllable.For these laSCI9. Differential masking of individual words within a sentence. stimuli,the RT wasnot influenced by theincrease of thenumber of morae. TheodoreS. Bell (UCLA Schoolof Medicine,Head & Neck Surgery, Theseresults suggests a possibilitythat a moroconsisting of a CV syllable 31-24 RehabilitationCtr., Los Angeles,CA 90024-1794) and Richard is the smallestsegment of the processingunit in Japanesespeech produc- Wright (UCLA, LosAngeles, CA 90024-1543) tion. However,tooroe consisting of a singlevowel or nasalsound cannot performas independentprocessing units. Threeexperiments tested the effectivenessof adjustingthe amplitude laSC16. Perceptual interaction of F1 and F0. Jose R. Benki of a noise maskerto selectivelyalter intelligibilityof individualwords (Linguist.Dept., Univ. of Massachusetts,Amherst, MA 01003) within sentences.Stimulus sentencescontained three key words; all were commonlyused and phoneticallyunique. A speech-shapednoise was pre- While F1 is a primary perceptualcorrelate of vowel height, other sentedat 65 dB SPL for all experiments.The initial studytested 12 lis- dimensionsof vowels,such as F0, covary with FI in naturalspeech. This teners under two conditions: the noise level remained flat, or was attenu- studyinvestigates the perceptualinteraction of F0 and FI in backvowels ated6 dB underthe middlekey word.The speechwas presented at 54 and usingthe Garnerparadigm. Two factorsare hypothesizedto determinethe 58 dB SPL. The middle key word improvedby as much as 30% (p interaction:the magnitudeof F I-FO and the locationsof the harmonics. <0.001), while otherkey wordswere unaffected. In the next two experi- FI and F0 are predictedto integratenegatively for vowels in a threshold ments,the noisewas either increasedor decreasedby 3 dB at a key word. region(3.0 Bark
3243 d. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3243
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp laSCZ2. Toward understandingthe role of formant transitionsfor laSC25. Quantitative measures of envelope cues in speech distinctionsof stopsfrom glides. Sally G. Revoile,Peggy B. Nelson, recognition. JohnnySaade (Dept.of Elec.Eng., Univ. of California,Los andLisa Holden-Pitt (GallaudetUniv., Ctr. for Auditoryand SpeechSci., Angelesand HouseEar Inst., Los Angeles,CA 90057), Fan-Gang 800 FloridaAve., N.E., Washington,DC 20002) Zeng,John J. Wygonski,Robert V. Shannon,Sigfrid D. Soli (HouseEar Inst.,Los Angeles, CA 90057),and AbeerAlwan (Univ.of California, Our understandingis incompleteof the propertiesof vowel formant Los Angeles,CA) transitionsthat contributeto distinctionsof voicedstop and glide conso- nantsin speech.Research appears to haveestablished some of the impor- A quantitativeprocedure is derivedto evaluatethe relative contribution tant transition cues for discernmentof bilabial synthetic stops versus of envelopecues to speechrecognition. Recognition data of 16 consonants glides.However, the stop/glidetransitions studied have typicallybeen in the/aCa/form were collectedusing signal-correlated noise stimuli in morestylized than those found in naturalspeech. This investigationex- sevennormal-heating listeners. Several distance measures were calculated aminedthe importanceof transitionsto listeners'identification of initial directlyfrom durationand amplitudeof the acousticenvelope. One am- stopsand glides in spoken/CVk/syllables.Performance was assessed for plitudedistance measure was the Euclidean distance which was computed the stopsand glides with progressivedeletion of segmentsfrom thesyl- fromthe squared difference of thesample-by-sample amplitudes. The sec- lables'onsets. Bilabial and velar stopsand glidesas well as alveolarstops ondmeasure was the envelope difference index (EDI) [Fortuneet al., Ear were tested in /Cbk/, ICokl, /Ca:k/ contexts to examine differencesin Hear.15. 93-95 (1994)]which was computed from the absolute value of transitionuse among phonemeenvironments. Twelve normal-hearing the differenceof the sample-by-sampleamplitudes. A multidimensional scalinganalysis was used to convertthe perceptualconfusion matrix imo youngadults participated as listeners.In general,when the initial stop a distance matrix and to normalize the different distance measures. Corre- burstswere deleted,the F2 transitionfrequency extent was significantly lationcoefficients were computedbetween the differentdistance measures correlatedwith subjects'consonant identification response patterns. That and the perceptualdata. Preliminary analysis of data from six stopconso- is, longerF2 frequencyextents yielded a higherpercentage of glidere- nantsshowed that the consonantduration alone is sufficientto explain the sponses.In addition,shorter F2 frequencyextents resulted in a higher perceptualdata (r=0.92). AlthoughEuclidean distance conveyed less in- proportionof "no initialconsonant" responses. Neither F2 transitiondu- formation(r=0.75) than duration,it was a bettermeasure than the EDI rationnor Fl transitionduration/frequency extent significantly correlated (r =0.31). Evaluationof thesemeasures on thefull 16 consonantset will be with the subjects'consonant identifications. discussed. 1aSC23. The role of formant synchronyin the coherenceof vowels. laSC26. Onset-sensitivetime-frequency masking and its application PeterC. Gordonand Erika Manning (Dept. of Psych.,Univ. of North to speechrecognition. Kiyoaki Aikawa (ATR Human Information Carolina,Chapel Hill, NC 27599-3270) Process.Res. Labs., 2-2 Hikaridai,Seika-cho, Soraku-gun, Kyoto, 619-02 Japan) The coherenceof vowelsas auditoryobjects was studiedby comparing identificationthresholds in noisefor syntheticvowel sounds (differing only This paper proposesan onset-sensitivetime-frequency masking in thecenter frequency of a singleformant) to identificationthresholds for mechanismin orderto improvedynamic feature extraction. Application of the distinctiveformant presented in isolation.The bandwidthof the noise the proposedmechanism to Japanese23-phoneme recognition using hid- maskerwas limited so that it only interferedwith perceptionof the dis- den Markovmodels demonstrated that onset-sensitive MASP outperforms tinctive formant.Thresholds for accuratelyidentifying the vowel sounds time-invariantMASP. MaskedSpectrum (MASP) [Aikawa et al., Proc. were lower than thosefor identifyingthe isolatedformant. This demon- ICASSP93II, 668-671 (1993)]is a newspectral representation incorpo- strates that vowel sounds cohere in the sense that unmasked formants ratingtime-frequency forward masking and hasbeen reported to provide reducethe maskingof a formantembedded in noise.The advantageof a excellentperformance when used for speaker-dependentand speaker- completevowel over an isolatedformant appears to dependon the tem- independentspeech recognition. The maskingpattern production mecha- poralalignment of theformants. When the onset of thedistinctive formant nismwas previously modeled by a time-invarianttime-frequency filter, but coincides with the offset of the other formants, then listeners can still the maskinglevel risesat the onsetsand offsetsin a speechsound [T. identify the vowel soundin modestarnourns of noise.However, in this Hirahara,J. Acoust.Soc. Jpn. El2 (2), 57-68 (1991); E. Miyasaka,J. case thresholds are not lower for vowel identifications than for identifica- Acoust.Soc. Jpn. 39 (9), 614-623 (1983)].This phenomenonsuggests tions of isolatedformants. This indicatesthat temporalsynchrony plays a that an adaptivemasking mechanism is effective for balancinginstanta- basicrole in the psychoacousticcoherence of vowels. neousand transitionalspectral features depending on vowelsor conso- nants. The maskingpattern is calculatedas the weighted sum of the 1aSC24. Dynamic and static properties of imaged speech sounds. smoothedpreceding spectra obtained by time-distance-dependentspectral DeborahA. Gagnon (Moss Rehab. Res. Inst., 1200 W. Tabor Rd., Philadelphia,PA 19141) smoothinglifters. The maskinglevel is controlledby the slopeof the temporalcontour of the instantaneoussound energy. The maskedspectrum is obtainedby subtractingthe maskingpattern from the currentspectrum. Thetype of informationstored in memoryfor speechsounds was tested Onset-offset-sensitivemasking models are alsoexamined. using a primed, speededclassification task. The relationshipbetween prime and targetwas variedin termsof phonemeconstituency, phoneme 1aSC27. Difference limens for vowel-vowel formant transitions. order,or both.Primes were presentedeither auditorally or visually,allow- William A. Ainsworth (Dept. of Commun.and Neurosci.,Keele Univ., ing for a contrastbetween perceptual and imagedspeech codes. Two other Keele,Staffordshire ST5 5BG, UnitedKingdom) manipulationswere made to assesswhether the temporalnature of the stimuli,the stimulusquality, or possiblyboth, play a role in deterlnining Seeond-formanttransitions in vowel-vowel utterancesare not always imageability:(1) õtimnil either contelnedatop (dynamically½uc•i) or fri of the>came duration as those of the first formcut m•d they often begin and catire(relatively statically cued) consonants; and (2) stimuliwere either end at differentinstants. In othercases the formantfrequencies sometimes naturalor synthetic.Inhibitory effects were foundwhen an auditoryprime first move in a different directionfrom their final targets.In order to was presentedat a 100-msISI, supportingearlier evidence for a position- investigatewhether these formant movements are perceptnellysignificant, ally specificperceptual speech code (Gagnon and Sawusch,1992). It was a number of difl•renee limens for formant transitions have been measured alsofound that both the manipulation of thetype of consonant(stop versus for synthesizedversions of the vowel pair lal-lil. It was found that difligr- fricative)present in the targeland the quMityof the stimulusset (natural encesin durationbetween the first- and second-formanttransitions of up to versussynthetic) had an effecton imageability,supporting both a temporal 70 ms were not perceived.It wasalso found that delaysbetween the starts nature(Surprenant, 1992) and stimulusquality accountof imageability. and ends of the first and secondtransitions of up to 50 ms were not These results will be discussed within the context of current theories of perceived.These results suggest that the differencesin durationsand de- memory,imagery, and speechperception. [Work supportedby NIDCD lays betweenthe first and secondformants found in naturalvowel-vowel Grant R01 DC00219 to SUNY at Buffalo and Mark Diamond Research utterancesare unlikely to be of perceptualsignificance. [Work supported Fundgrant to DeborahA. Gaghon.] by EC ScienceCoutract SC1-CT92-0786.]
3244 d. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3244
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp laSC28. Female alaryngeal speech enhancement for improved IASC31. Perception of voice-onset-time cued by articulatory speaker identification using linear predictive synthesis. RenettaG. information. David R. Williams (SensimetricsCorp., 26 Landsdowne Tull, JanetC. Rut/edge,and Jerry J. Mahler (Elec. Eng./Comput.Sci. St., Cambridge,MA 02139) Dept.,Northwestern Univ., Evanston,IL 60208) This paperpresents results of a first perceptualassessment of VOT Linearpredictive synthesis was applied to femalealaryngeal speech as continuasynthesized using articulatory rather than acousticparameters. an enhancementtechnique to reduce genderambiguity during speaker The researchemployed Sensimetrics' HLSYN synthesissystem, which identification.Esophageal speech, a form of alaryngealspeech resulting embodiesan articulo-acousticmodel of speechproduction [K. N. Stevens from the removal of the larynx due to cancer, perturbsthe theoretical and C. A. Bickley,J. Phon.19, 161-174 (1991)]. The systempermits acousticmodels for laryngealspeech. This form of pathologicalspeech time-varyingcontrol of fundamentalfrequency, vocal-tract shape, and of alsochanges the expectedspectral characteristics and affectsperception. glottal,oral, and nasalorifice sizes; calculated aerodynamic quantities pro- The femaleesophageal speaker's low fundamentalfrequency often causes her to be identifiedas a malespeaker over telephone lines. The errorsmade vide the basisfor estimatingKLSYN88 synthesizersource parameters. Six in speakeridentification can be reducedby obtainingvocal tract param- 10-memberVOT continua(/ba/-/pa/,/da/-/ta/,/ga/-/ka/,/bi/-/pi/,/di/-/ etersof the aperiodic,esophageal speech input from a linear predictive til,/gi/-/ki/) wereconstructed by varyingthe glottaladduction trajectory coding(LPC) modeland resynthesizingthe LPC predictioncoefficients sothat voicingonset occurred 0, 15, 30..... or 135 ms afteroral release.In usingan appropriatepitch period that is bettersuited for femalevoice. This addition,two peak glottal openings (18, 30 mm 2) were tested; for/a/, rate enhancementtechnique was implementedusing the TMS320C30 floating of oral releasewas alsovaried (slow, fast). Subjectsrated the "goodness" pointdigital signal processor from Texas Instruments. This implementation of the CVs as exemplarsof the appropriatevoiceless stop on a ten-point supportsthe potentialof a portableprocessor that enhancesthe perceptual scale.In general,subjects preferred longer VOTs for velarsthan for labials. quality of the female alaryngealvoice and improvesthe input speechsignal For alveolars, longer VOTs were preferred before/i/than before/a/. Ef- usedby both humanlisteners and automaticspeech and speakeridentifi- fects of peak glottal openingand oral releaserate on VOT preferences cation systems. were negligible.The resultsare discussedrelative to traditionalfindings for laSC29. Vocal tract simulations based on fluid dynamic analysis. acousticallydefined VOT continua.[Work supported by NIMH.] G. Richard,M. Liu, D. Sinder,H. Duncan,Q. Lin, J. Flanagan(Rutgers laSC32. A computationallyefficient articulatory synthesizer. Jacob Univ.--CAIP Ctr., Piscataway,NJ 08855-1390), S. Levinson (AT&T Reel, JamesChang, and Abeer Alwan (Dept. of Elec. Eng., 66-147E Bell Labs.,Murray Hill, NJ 07974), D. Davis,and S. Simon (General Dynamics,Groton, CT 06340) Engr.IV, UCLA, 405 HilgardAve., Los Angeles, CA 90095)
An alternateapproach to speechsynthesis based on direct numerical In this study,a computationallyefficient articulatory synthesizer that solutionof Navier-Stokes(NS) and Reynolds-averaged-Navier-Stokes utilizesthe popularanalog circuit simulator SPICE is developed.The syn- (RANS) equationsis described.Unlike the traditionalmethods based on thesizeruses a transmission-lineanalog model of the vocaltract. An analog linearacoustic theory, the NS and PANS formulationsare not limited by modelhas many advantages over digital representations: (1) Sidebranches the assumptionsof linearity,negligible viscous effects, and plane-wave (neededfor modelingnasals and/I/) can be simulatedeasily by additional propagation.The expectedresults are high-qualitysynthesis and a new transmissionlines in parallel;(2) drive-dependentsources, at any location, parametrizationof speechfor applicationsin automaticrecognition and could be added; and (3) the number of sectionscan be varied without low bit-ratecoding resulting from a parsimoniousmodeling of articulatory changingthe samplingrate, as is the casewith a digital synthesizer.A shapesand dynamics.In the presentformulation, the Navier-Stokes equa- computerinterface, using MATLAB, is developedsuch that the inputto the tionsare discretized and solvedusing a finite-differencemethod. An initial synthesizercan be specifiedin termsof the areafunction of the vocaltract applicationinvolves a 2-D simulationof flow throughideal channels andthe type and location of dependentor independentsources (voltage or (straight,dilating, and constrictingtubes) with rigid walls and constant current.)By simulatingthe transferfunction of the vocaltract, transient boundaryconditions (constant flow velocityat inlet,zero pressureat out- and steady-stateresponses are generated.Using Fant's vowel area func- let). As expectedfor thesesimple geometries, the resonancefrequencies tions (1960), vowelswere synthesizedwith their first four formantfre- correspondto thosepredicted by linearacoustics. In a secondapplication, quenciesalmost identical to thosegiven by Fant.The feasibilityof imple- the formulationis appliedto the geometryof the threecardinal vowels. For thesecases, periodic inflow boundary conditions are alsoused (a trainof mentingthe analogsynthesizer using modem ICs, suchas the gyrator- shortpulses to representvocal cord excitation). Synthetic speech sounds of based inductancesimulator and switched capacitor filter circuits, is encouragingquality are obtained for the three vowels. [Research supported assessed. by NSF/ARPAIRI-9314946 and ARPA DAST 63-93-C-0064.] laSC33. Identification of vowels resynthesized from /hVd/ laSC30. Removal of phase distortion from vowel-like signals. utterances:Effects of formant contour. JamesHillenbrand (Speech KentonA. ShipIcy,alCasey R. Winkel,and P G. Vaidya(Dept. of Mech. Pathokand Audiok, Western Michigan Univ., Kalamazoo, MI 49008) andMater. Eng., Washington State Univ., Pullman,WA 99164) The purposeof thisstudy was to examinethe role of formantfrequency In thispaper, specific types of signalsare considered. To generatethese movementsin vowel recognition.Measurements of fundamentalfrequency signals,we beginwith x(t)=A cos[wt+qb(t)], where A and w arecon- and formant contours were taken from a database of acoustic measure- stants,but 4fit) is a functionof time generatedby a randomwalk. The other mentsof 1668 /hVd/ utterancesspoken by 45 men, 48 women,and 46 stepto generatethe final signalis to passx(t) througha nonlinearfilter children[Hillenbrand et el., J. Acoust.Soc. Am. 97 (in press)].A totalof suchthat, were 4fit) to be constantthe outputwould be of simpleharmon- 300 utteranceswere selectedfrom this database,representing equal num- ics at w, 2w, 3w, etc. However, since x(t) is nonstationary,the output bersof 12 vowels(i,t,e,e,a•,a,v,o,u,u,^,•) and approximatelyequal num- signal, say y(t), would also be nonstationary.It would be shownthat bers of tokensproduced by men, women, and children.Listeners were humanvowel signalsseem to follow this nonlinearpattern. It is of interest askedto identifythree versions of eachutterance: (l) theoriginal, naturally to remove(or modify)the phase distortion due to therandomness of 4,(t). producedsignal, (2) a formant-synthesizedversion that followed the mea- Thishas been accomplished by usingtwo differentmethods. One uses the sured contour• of FI-F3. and (3) a formant-synthesizedversion with trans-spectralcoherence technique [P.O. ¾aidyaand M. J. Anderson,I. Acoust.Soc. Am. 89, 2370-2378 (1991)] andthe otheruses the complex FI-F3 fixedat theirsteady-state values. Preliminary results indicate: (l) FFF componentsin a mannersimilar to a rigid bodyrotation in dynamics. the originalsignals are identifiedwith substantiallygreater accuracy than Thesemethods have been used to produceboth distortion-free and highly eitherof the syntheticversions, and (2) the syntheticsignals that follow the modulatedversions from a givenhuman vowel signal. a•Now at Martin original formantcontours are identifiedwith greateraccuracy than the Marietta, Knolls Atomic Power Labs, Schenectady,NY. flat-formant signals.
3245 J. Acoust.Soc. Am., Vol.97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3245
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 1aSC34.Speech synthesis based on an overlap-addsinusoidal model. IASC37. Toward automatic segmentation and syllabification of MichaelW. Maconand Mark A. Clements (Dept.of Elec. and Comput. dysarthricspeech. GuangsbengZhang and H. TimothyBunnell (Univ. Eng.,Georgia Inst. of Tech.,Atlanta, GA 30332) of Delaware,Dept. of Linguist.,and SpeechProcess. Lab, A. 1. dupont Inst., 1600Rockland Rd., Wilmington,DE 19899) A generalframework for waveformsynthesis in a concatenation-based text-to-speechsystem is presented.Natural speech is segmentedinto sub- A programhas been developed which usesheuristic processing of the wordunits and analyzed using an iterativeanalysis-by-synthesis procedure outputof a neuralnetwork to locate syllableboundaries in connected originallypresented in [E. B. Georgeand M. J. T Smith,J. AudioEng. speech.The neuralnetwork attempts a broadsegmental (8 category)clas- Sec. 40, 497-516 (1992)]. Synthesisis then performedby an efficient siftcation.This is followedby a programwhich locates syllable boundaries overlap-addresynthesis and modification method. This methodeliminates usingphonelogical constraints and the patternof networkclassifications the needfor precise,hand-corrected pitch pulse marking in analysis{as over time.On testdata consisting of 150sentences (about 1800 syllables) from the TIMIT database,this programcorrectly identifies between 83% requiredin someother popular concatenation methods), by incorporatinga and 88% of the syllableboundaries (depending on the errorcriteria), in- pitchpulse onset time estimation function based on [R. J. McAnlayand T. cludingsyllables bounded by sorterantconsonants and syllablescontaining F. Quatieri,Proc. ICASSP, 1713-1715 (1986)]. The sinusoidalmodel is syllabic consonants.This programis now being applied to the identifica- capable of natural-soundingpmsodic modificationof both continuous tion of syllable boundariesin speechfrom talkers with cerebralpalsy. In speechand concatenated segments, making it an idealcandidate for appli- preliminaryanalyses of 20 sentencesfrom ten dysarthrictalkers (140 syl- cationin a T17Ssystem. Furthermore, the modelprovides for a computa- lables)only 12 boundaryomissions occurred. However, since dysarthric tionallytractible and conceptually simple decoupling of variousproperties speechoften containshesitations, false starts,and extraneousnoises, as- of thespeech signal, making it anexcellent platform for othertransforma- sessingboundary insertion errors is more difficult;about 50 boundary tionsof the synthesizedspeech. insertionsoccurred. Roughly 2/3 of theserepresented instances in which 1aSC35. Generating gestural scoresfrom articulatory data using the talker insertedadditional syllabic features into the speech.Further temporal decomposition.Michael J. Collins, StanleyC. Ahalt, and studieswill examinemethods for reducingthe numberof these"unin- tended"boundaries ideatitled by the algorithm.[Work supported by the Ashok K. I•rishnamurthy {Dept. of Elec. Eng., The Ohio State Univ., NemoursFoundation.] Columbus,OH 43210) 1aSC38. Adding articulatory features to acoustic features for Throughempirical investigations, the automaticgeneration of gestural automaticspeech recognition. Igor Zlokarnik (Los AlamosNatl. Lab., scoresfor articulatorydata corresponding to consonant-vowel-consonant C1C-3, MS B256, Los A!amos,NM 87545) (CVC) tokenswas studied.The articulatorydata consist of the movements of fleshpoints measured using an x-raymicrobeam, and is first"warped" A hidden-Markov-model(HMM) basedspeech recognition system was to resemble the vocal tract variables of constriction location and constric- evaluatedthat makesuse of simultaneouslyrecorded acoustic and articu- tion degree.The multichannelwarped data are then analyzedusing tem- latopj data. The articulatorymeasurements were gatheredby meansof poraldecomposition. The resultingtarget functions provide candidates for electromagneticarticuiography and describethe movementof small coils gestures,from which the bestcandidates are chosenstatistically by exam- fixed to the speakers'tongue and jaw during the productionof German ining the magnitudesof the elementsof their associatedreconstruction V•CV 2 sequences[P. Hooleand S. Gfoerer,J. Acoust.Sec. Am. Suppl.1 weights.Onset and durationalanalysis of the candidatetarget functions 87, S123(1990)]. Using Ihe coordinatesof the coil positionsas an articu- resultin the gesturalscore. Human and Elman RecurrentNeural Network latory representation,acoustic and articulatoryfeatures were combinedto recognitiontests are performedto ascertainthe accuracyof the generated make up an acoustic-articulatoryfeature vector. The discriminantpower gesturalscores. Comparisons with "correct"gestural scores are alsoper- of this combinedrepresentation was evaluatedfor two subjectson a formed.The resultsof thiswork should provide a steppingstone for future speaker-dependentisolated word recognitiontask. When the articulatory acousticand aniculatorybased recognizers employing the samestrategy. measurementswere usedboth for trainingand testingthe HMMs, the articulatoryrepresentation was capableof reducingthe error rate of com- 1aSC36. Layered language understander: A speech recognition parableacoustic-based HMMs by a relativepercentage of morethan 60%. systemusing layered abduction. KevinA. Lenzo (ATR Interpreting In a separateexperiment, the articulatorymovements during the testing Telecomman.Res. Labs., Dept. 3, 2-2 Hikaridai, Seika-cho,Soraku-gun, phasewere estimatedusing a multilayerperceptton that performedan Kyoto, 619-02 Japan), John Josephson,Osamu Fujimura, and acoustic-to-articulatorymapping. Under these more realistic conditions, ChristopherBailey-Kellogg (Ohio StateUniv., Columbus,OH 43210) whenarticulatory measurements are only availableduring the training,the error rate couldbe reducedby a relativepercentage of 18% to 25%.
A speechrecognition system is underdevelopment in whicha general- 1aSC39. Vocal tract normalization in speech recognition: purposeinference engine for natural languageprocessing is loaded with Compensating for systematic speaker variability. Jordan Cohen domainknowledge and a preprecessingperiphery that allowsfor the inte- (CCR-IDA, Princeton,NJ), Terri Karore, and Andreas G. Andteen gration of prosedit information. Processingtakes place in well-defined (JohnsHopkins Univ., Baltimore,MD 21218) layers, in which resultsat one level of abstractionbecome data to be explainedby hypothesesin the next, usinga layered-abductioninference The performanceof speechrecognition systems is oftenimproved by mechanismthat allowsfor integrationof both top-downand bottom-up accountingexplicitly for sourcesof variability in the data In •he RWITC't-I- information[J. R. Josephsonand S. G. Josephson,eds., Abductire Infer- BOARD corpus,studied during the 1994 CA1Pworkshop [Frontiers in ence:Computation, Philosophy, Technology (Cambridge U. P., 1994)].The SpeechProcessing Workshop II, CAIP (August1994)], an attemptwas hypothesistypes and their interactionsare based upon the converter/ madeto compensatefor the systematicvariability due to differentvocal distributormodel of phoneticimplementatiou [ O. Fujimura, "Syllable tractlengths of variousspeakers. The methodfound a maximumprobabil- Timing Computationin the C/D Model," Proceedingsof the Third Inter- ity parameterfor each speakerwhich mappedan acousticmodel to the nationalConference on SpokenLanguage Processing (1994)]. Eachhy- meanof the modelstaken from a homogeneousspeaker population. The pothesisis annotatedwith a numericalmagnitude that is usedin computing underlyingacoustic model was that of a straighttube, and the parameter a "prosodiccontour" for the overallutterance, which aids in the genera- estimationwas accomplishedby warpingthe spectrumof eachspeaker tion of expectations,implications, and knowledge of whichhypotheses can linearlyover a 20% range(actually accomplished by digitallyresampling accountfor whatdata. Preprecessing events are explainedby the features, the data),and finding the maximuma posterJoriprobability of the data which,in turn,are explainedby hypothesesat the demisyllabiclayer, the giventhe warp.The techniqueproduces statistically significant improve- syllabiclayer, and, finally, by the word-levelhypotheses. mentsin accuracyon a speechtranscription task usingeach of four dif-
3246 J. Acoust.Soc. Am., Vol.97, No. 5, Pt. 2, May 1095 129thMeeting: Acoustical Society of America 3246
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp femnt speechrecognition systems. The best parametrizationswere later voicesource and the vocal tract. Preliminary results of adaptivemimicking foundto correlatewell with vocaltract estimates computed manually from usingTRACTTALK are presentedand discussed.[Work supportedby spectragrams. ARPAContract #DAST 63-93-C-0064.]
IASC40. Use of TRACTTALK for adaptive voice mimic. Qiguang Lin, GaelRichard, Jingyun Zou, Dan Sinder,and James Flanagan (CAIP laSC41. Effects of syllable duration on syllable-final stop-glide Ctn, RutgersUniv., Piscataway,NJ 08855-1390) perceptionby humansand monkeys. JoanM. Sinnott (Comparative HearingLab, Psych.Dept., Univ. So. Alabama,Mobile, AL 36688), MelissaA. Borneman,and Paul A. Dagenais (Univ. So.Alabama, Mobile, Variousspeech-processing technologies necessitate parametrization of AL 36688) the speechwaveform. Cepstmm coefficients (including their derivatives and variants)are to date commonlyused in speechand speakerrecogni- tion. This paperseeks more compactparametric description of speech Humansand monkeyswere comparedin their perceptionof phoneme informationbased on the adaptive voice mimic [Flanagan et al., J.Acoust. boundaryshifts along two syntheticsyllable-final stop-glide/bob/-boU/ Soc.Am. 68, 780-791 (1980)].The mimic system utilizes an articulatory- continuadiffering inoverall syllable duration (150 vs 320 ms). Humans were first testedwith a written identificationprocedure and showeda basedspeech synthesizer to generatesynthetic speech, which is adaptedto boundaryshift to longertransition durations with increasedsyllable dura- arbitraryspeech input. The perceptuallyweighted spectral difference be- tion, aspreviously reported in the literaturefor syllable-initialstop-glide tweenthe input and synthesizedspeech is next minimizedby optimizing /bo-wo/ data.Humans ahd'monkeys were then tested with a low- the underlyingarticulatory parameters until the differenceis drivenbelow uncertaintydiscrimination procedure but showed liale evidence of a a predeterminedlevel. The resultantrepresentation, adapted moment by sensory-leveldiscontinuity underlying the identifiedboundaries: Instead moment,provides efficient parametrizationof the signal informationby sensitivityappeared to follow Weber'slaw. Finally,both human and mon- whichthe problemsof speechsynthesis, speech recognition, and low bit- keys were testedwith a go/no-goidentification procedure specifically de- ratespeech coding are coalesced into a compactframework. In thispaper, signedfor monkeys.Both speciesclearly showedthe shift effect, but an articulatoryspeech synthesizer,TRACITALK, is first described. quantitativedifferences emerged between the speciesthat weregenerally TRACTTALK simulatesthe vocal tract basedon principlesof linear consistentwith comparativepsychoacoustic measures of temporaldis- acousticsand incorporatesfeatures which includeinteraction between the crimination.[Work supported by NIDCD.]
TUESDAY AFTERNOON, 30 MAY 1995 RENAISSANCE WEST A, 1:00 TO 5:35 P.M.
SessionlpAO
AcousticalOceanography: Ocean Acoustic Tomography: Observing the Ocean in the 1990slI
Bruce M. Howe, Cochair AppliedPhysics Laboratory, University of Washington,1013 N.E. 40th Street,Seattle, Washington 98105 B.Edward McDonald, Cochair Naval ResearchLaboratory, Washington, DC 20375
Chair's Introduction--l:00
Invited Paper
1:15
lpAO1. What acoustictomography can tell us about the state of the ocean:Theoretical considerations. Robert N. Miller (Collegeof Oceanicand Atmos. Sci., Oregon State Univ., Corvallis, OR 97330) Acoustictomographic data consist of line integralsof soundspeed along ray paths. The communityhas little experience with line integraldata, and most of themethods for mappingoceanic properties and for dataassimilation (i.e., combining observed data with resultsfrom dynamical models) have been designed and tested with point measurements in mind. In thiswork, the tools of estimation theorywere used to investigatethe potential for reconstructing time series of oceanicpressure and density fields by assimilation of line integraldata into a simpleocean model. Under ideal conditions, with noise-free data and ocean dynamics given exactly by a simple combinationof linearwaves, time seriesof integralquantities along the edgesand diagonals of a squarearray are sufficientto determinetime series of amplitudes ofa largecollection ofwaves, most of whose wavelengths aremuch shorter than the length of the edgeof thearray. Simulation experiments were performed to investigatethe consequences of imperfect, possibly nonlinear dynamical oceanmodels and noisy data.
3247 d. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3247
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp ContributedPapers
2:10
lpAO2, Testing a regional ocean model using acoustic travel time lpAO4. A 4-D view of convection by assimilation of acoustic and observations. Brace D. Comuelle, Peter E Worcester, David B. classicalmeasurements. F. Galliard,Y. Desaubies(Lab. de Phys.des Chester (ScrippsInst. of Oeeanogr.,Univ. of Californiaat SanDiego, La Oc6ans,IFREMER, BP 70, 29280Plouzan6, France), U. Send,and E Jolla, CA 92093), Brian D. Dushaw,and Brace M. Howe (Univ. of Schott (IFM, 2300Kiel, Germany) Washington,Seattle, WA 98105-6698) Acoustictomogmphy has beenapplied to observationof wintercon- The AcousticMid-Ocean Dynamics Experiment (AMODE) measured veerionin the Gulf of Lion duringthe THETIS-I experimentconducted time seriesof reciprocalacoustic travel time and temperaturewith a 700- duringthe 1991-92 winterby a Europeangroup (I]FM Kiel. IFREMER km-diam array of six mooringssouth of Bermudaduring 1991-1992. Brest,and IACM Heraklion).A globalanalysis of all typesof temperature Time-independentinversions give a seriesof snapshotsof the barotropic measurementscollected during THETIS 1 will be presented.Data issued and barocliniceddy field. Observationstaken at different times can be from temperaturesensors, thermistor chains, and CTD havebeen merged combined,using a dynamicalocean model, to generateimproved estimates with the tomographicmeasurements in orderto recoverthe time evolution of the evolving eddy field, provided that the model is accurate.The of the full 3-D temperaturefield. The methodrelies on inversionand AMODE observationshave been used to test a nonlinear.quasigeo- Kalmanfiltering methods. It can be consideredas a new steptoward strophie,limited-area ocean model by attemptingto fit a long-termdataset, "observationsystems." Monitoring of the wholearea during the "precon- andby initializingthe modelwith a 'training'dataset and thenpredicting ditioning"phase shows the influenceof surfacecooling on the vertical forwardin time for comparisonto datanot usedin theinitialization. Using stratification.This effectis inhomogeneousand the situationevolves with an rms error measureof misfit betweenthe observationsand the predicted time, influencedby horizontaladvection. The relative importanceof sur- data, the model predictionhas 40% less error than persistenceover 12 face forcing and advectionis responsiblefor the intermittentnature of days, and about 20% lesserror than persistenceover 24 days.The extent convectionwhich happenswith differentintensity from year to year.After to which the data misfit is sensitiveto external model parameters,soch as convection,the behaviorof the mixed water chimneyand the evolutionof the radius of deformationor viscosity,allows the parametersto be opti- the verticalprofile towardthe initial stateis documented. mized to give maximumpredictability, and also gives a measureof how
wellthe model has been tested by thedataset. [Work supported by ONR.] 2:25
1:55 lpAOS. Evolution of the large-scale •emperature field in the GreenlandSea during 1988-89 from tomographic measurements. lpAO3.. Assimilating tomographic travel time data using an open WernerM. L. Morawitz,Peter F. Worcester,Bruce D. Cornuelle(Scripps ocean circulation model. Chris G. Waiter, Bruce M. Howe, James A. Inst.of Oceanogr.,Univ. of Californiaat SanDiego, La Jolla,CA 92093), Mercer (Appl.Phys. Lab., Univ. of Washington,Seattle, WA 98105),and PhilipJ. Sutton (New ZealandOceanogr. Inst., Kilbirnie,Wellington, RobertN. Miller (OregonState Univ.) New Zealand), JamesF. Lynch (WoodsHole Oceanogr.Inst., Wooers Hole,MA 02543),and RichardPawlowicz (Inst. of OceanSci., Sidney. Observingand predictingthe ocean'smeso-scale circulation presents a BC. Canada) formidabletask for oceanographers.Ocean acoustictomography uses travel times between acoustic sources and receivers to measure the ocean's Moored thermistor,hydrographic. and tomographicmeasurements low wave-numbersound speed (temperature) and currentfields. Experi- havebeen combined using least-squares inverse methods to studythe evo- mentsare being performedwith simulatedocean data to determinethe lutionof the 40 km and largerthree-dimensional temperature field in the relativeeffectiveness of tomographicand point measurements in constrain- GreenlandSea during winter 1988-89. In February,the sub-surfacetern- ing a numericalcirculation model. The primary tool is data assimilation, peraturemaximum at around200-m depthdisappears over a largearea. i.e., .anoptimized combination of modeloutput and observations.Relative Upper waterswarm aroundthis time, while intermediatewaters cool, con- weightsof observationand modeloutput are basedon a priori estimatesof sistentwith verticalmixing. A chimneystructure reaching depths in excess the model and observation error covariance. Results from identical twin of 1000m is observedto the southwestof the gyrecenter during March. simulationsusing tomographic and point measure.meats are presented.In The chimney has a spatialscale of about 50 kin. a fime scaleof about l0 the twin experiment,two assimilationschemes are examined,one in which days,and breaksup in about3-6 days.A one-dimensionalvertical heat the estimatedmodel error covarianceis fixed (optimalinterpolation) and balanceadequately describes changes in total heatcontent in the chimney anotherin which a Monte Carlo [G. Evensen,1. Geophys.Res. 99, regionfrom autumn1988 until the time of chimneybreak-up. A simple l0 143-10 162 0994)] methodis usedto estimatethe modelerror eova- one-dimensionalmixed layer model is successfulin reproducingfall to riancedynamically. Error statistics of the energyand flux fieldsare usedto winter bulk temperatureand salinitychanges, as well as the observed quantifythe performancefor eachobservation and updatingscheme. The evolutionof the mixedlayer. The estimatedannual deep water production numberof measurementsrequired to achievea targeterror level is esti- ratein theGreenland Sea for 1988-89is about0. l Sverdrups,comparable matedfor eachmethod. [Work supported by ONR andby the Strategic to the decreasedproduction rates since 1983 derived from tracer measure- EnvironmentalResearch and Development Program through ARPA.] ments.[Work supported by NSF andONR.]
2:40-2:55 Break
Invited Paper
2:55
lpAO6. Basin-scale tomography in the western Mediterranean. Uwe Send (Inst. f/Jr Meereskundean der Univ. Kiel, DfisterubrookerWes 20, 24105Kiel, Germany) An internationalacoustic tomography experiment had been deployed in thewestern Mediterranean from January to october1994. Seventransceivers spanned the region between France, Algeria, the Balestic Islands, and Sardinia/Corsica. The basin (maximum range 600 km)was "illuminated" by a singleHLF-5 source,the remaining sources had a shorterrange but could communicate with their neighbors.Extensive hydrographic measurements and analysis of historicaldata accompanied the observations, including a large-scale
J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3248
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp surveyduring deployment and recovery and a 2-weeklyXBT section along the main transmission path. Some paths went along/through complicatedtopography, and in additiona shipboard acoustic survey was carried out to studythe propagation into shallow water. All instrumentsremained operational for the entire period, and 6 of the7 had100% return of receiveddata. The receptions show a high S/N ratiowith well-resolved arrivals that agree well with acoustic propagation predictions. The seasonal variation of thetravel times appearsto bea goodmeasure of thecycle of thelarge-scale heat content. The 3-D basin-averagedtemperature is estimated to have anaccuracy of 3%-4% of theseasonal amplitude. A system like this, installed with shore-cabled instruments, should be a valuabletool for monitoringinterannual and climate-scale water mass variability.
Contributed Papers
3:20 traveltime/RD in therange-dependent channel differs from the travel time tp,•through the range-averaged channel. In raytheoretical regime, a warm lpAO7. Characteristicsof signals recorded near shore in the bias(rRDIRA)caused by mesoscaleeddy in modetheory regime. [Work sup- Terre (LPO/IFREMER), B. Faure (CEPHAG, Grenoble),and F. portedby ONR,ARPA, and NOAA.] Gaillard (LPO/IFREMER)
Most of the westernMediterranean coast is characterizedby a narrow shelfand steep rise. Thus it shouldbe fairlyeasy to installsources and/or receiverscabled to shorefor permanentacoustic monitoring of the basin. The studyof the feasibilityof this optionwas one of the goalsof the 4:05 THETIS 2 project.Results of a ship-borneacoustic survey over the con- lpAO10. Ocean structure inversion by horizontal refraction tinentalrise will be presented.Signals were recorded at 26 stations,open- tomography.A. G. Voronovichand E. C. Shang (CIRES,Univ. of ingup in range,with an 8-channelvertical array. Several of thereceptions Colorado/NOAA/Environ.Technol. Lab., 325 Broadway,Boulder, CO implementeda synthetic aperture array concept. Where available, the re- 80303) sultswill be comparedto thoseobtained at FrenchNavy, fixed hydro- phoneslocations, in particular,a longtime series at a singleshallow water hydrophone.[Work supported by EC/MASTand IFREMER.] Numericalsimulations for the horizontalrefraction tomography (HRT) proposedpreviously [A. G. Voronovichand E. C. Shang,J. Acoust.Soc. Am. 95, 2851(A) 0994)] wereconducted. HRT is basedon measurements of horizontalrefraction angles (HRA) relatedto differentacoustic modes. 3:35 HRA aremeasured with the help of twodistant ocean interferometers (each one consistsof a pair of long moderesolving vertical arrays separated lpAO8. Large-scale circulation and variability in the northwest about10 km apart).The signalis producedby tonaltowed acoustic source. Atlantic as determined by long-range reciprocal acoustic Bothmodel eddy and real oceaniceddy of 100 kmx100 km scalemea- transmissions. David B. Chester, Peter F. Worcester, Bruce D. suredin CanaryBasin were used for simulations.The 3-D tomography Cornuelle(Scripps Inst. of Oceanogr.,Univ. of Californiaat SanDiego, inversionproceeded in twostages: (1) retrievingthe values of propagation La Jolla, CA 92093), and Brian D. Dushaw (Univ. of Washington, constantsin the knotsof a horizontalrectangular greed (linear 2-D prob- Seattle,WA 98105) lem)and (2) reconstructionof the sound-speed profile (SSP) in eachknot Reciprocalacoustic transmissions are analyzedto determinethe gen- (l-D nonlinearproblem). Up to 81 valuesof propagationconstants for eral circulationof the regionbetween Bermuda and PuertoRico. Six to- each mode were retrieved in both cases. Then SSP were calculated in each mographictransceivers were moored from March 1991to March1992 in knotwith the helpof a specialinvariant-imbedding based procedure. With the regioncentered at 25øN, 66øW duringthe AcousticMid-Ocean Dy- error-freesimulated HRA data,SSPs were exactly reconstructed. The ef- namicsExperiment (AMODE). Large-scale range averages (over 300 to fectof errorson tomographyinversion and requirements to theaccuracy of 700 km sections)of temperatureand velocityand large-scaleareal aver- phasemeasurements were also estimated. [Work supported byONR.] agesof relativevorticity have been estimated through inversion of tombg- raphictravel time data. The barbtropicand first baroclinic mode are well resolvedby the acousticsampling, with poorerresolution of the second barbclinicmode. The 300-daymean circulation of the regionindicates a band of westward flow of a few cm/s in the surface and thermocline 4:20 waters.An active and resolvablemesoscale eddy field is present,with lpAOll. Ocean tomographyvia matched-fieldprocessing. A. variabilitytypically dominated by motionswith spatialscales of 100-200 Tolstoy (integratedPerformance Decisions, 4224 WaialaeAve., Ste. km, andwith a generalwestward drift of mesoscaleeddy features. The 5-260, Honolulu,HI 96816) and B. Sotirin (NCCOSC-NRaD, San tombgraphicobservations have been combined with a quasi-geostrophic Diego,CA 92152) numericalocean model to furtherinvestigate eddy kinematicsin the re- gion.The model is usedboth to evaluatethe evolution of thebarbtropic and baroclinicflow field, and to illustratethe utility of tombgraphicdata The tombgraphicdetermination of 4-D oceansound speeds depends forconstraining a quasi-geostrophic model. [Work supported byONR.] uponthe nature of thesystem design, the analysis technique, and upon the resourcesused for generatingand measuring the acoustic fields sampling theocean region of interest.Matched-field tomography has recently been proposedas a high-resolutionmethod potentially Capable of synoptically 3:50 imagingocean regions as large as 1000by 1000km withrms accuracies lessthan 1 m/s[A. Tolstoy,J. Comput.Acoust. 2(1), 1-10 (1994)].How- lpAO9.Acoustic travel time biases caused by mesoscaleeddy. E.C. ever,all resultsto datefor the determinationof deepocean sound-speed $hang.Y. Y. Wang.and A. G. Voronovich (CIRES. Univ. of Colorado/ profileshave been simulated.A major drawbackto the actual implemen- NOAA/Environ. Technol. Lab., Boulder, CO 80303) tationof thetechnique has been the requirement for severallong (1000 m) Smaller scale fluctuationscan be smooth-outby taking a long range verticalarrays• and these arrays have been neither affordable nor readily propagationunder linearized assumption. But thenonlinearity of theequa- available.New technologyis on the vergeof producingrelatively inex- tionsrelating ocean perturbations to acoustictravel times leads to a biasif pensive,air-deployable, lightweight versions of thesearrays suggesting theproblem is linearizedabout a range-independentreference state. The thatthe MFP methodmay soon be testable. [Work supported by ONR.]
3249 d. Acoust.Soc. Am., Vol. 97, No.5, Pt.2, May1995 129thMeeting: Acoustical Society of America 3249
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 4:35 5:05
lpAO12. Investigation of the layered bottom structure influence on lpAO14. Determination of the inhomogeneity position by the time propagation of high-frequencyacoustic signals. MargaritaS. Fokina structure of a scatteredsignal. Vladimir N. Fokin and MargaritaS. andBoris V. Kerzhakov (Inst. of Appl. Phys.,Russian Acad. of Sci., 46, Fokina (Inst. of Appl. Phys.,Russian Acad. of Sci., 46, UlyanovSt., UlyanovSt., 603600Nizhny Novgorod, Russia) 603600,Nizhny Novgorod,Russia)
Peculiaritiesof frequency-angledependences of Fresnel'sreflection The methodis basedon the fact thatthe meanvelocity of soundpulse coefficientsV(fd, O) (f=frequency,d=layer thickness,0=grazing angle) propagationalong the ray trajectorydepends on the angleof the ray exit. froma systemof elasticlayers on theelastic substrate are investigated. The Theefficiency oftile method isanalyzed numerically forthe signal recep- methodof calculatingthe phase and the module of thereflection coefficient tionat a horizontalarray and a singlehydrophone. It is shownthat the from the layeredelastic absorbing substrate is numericallyrealized. The signalof illuminationmay be suppressedand the scatteredsignal may be resonantbehavior of thereflection coefficient at differentgrazing angles separatedby time gating.It is also shownthat the depthof the deposition for a given bottommodel is investigated.The influenceof the set of of a space-localizedinhomogeneity may be estimatedby the widthof the parametersof bottomlayers and the substrateon the frequency-anglede- scatteredsignal autocorrelation function. The distanceto the inhomogene- pendenceof the reflectioncoefficient and the behaviorresonance of the ity may be definedby the crosscorrelation function of the scatteredsignal reflectioncoefficient is considered.The effectsof the layerstructure of the at variousarray receivers. The influenceof the depthof the submergence elasticabsorbing bottom on the space-frequencydependences of acoustic of a scatterer and the distance between a source and a receiver on the fieldsin oceanicwaveguides in the frequencyrange 20-1000 Hz is stud- scatteredsignal structure is analyzed.[Work supported by RFFI projectN ied. The relationshipbetween the type of sedimentsthat formsbottom 94-05-1725-a.] layersand frequencyranges, where the leastlosses due to propagationare 5:20 observed,i.e., optimumpropagation frequencies, is ascertained.[Work supportedby RFFI projectN 94-05-1725-a.] lpAO15. Definition of geoaconstic characteristics of an elastic •ayered bottom using the spatial dependenceof an acoustic field. MargaritaS. Fokina,Vladimir N. Fokin,and Boris V. Kerzhakov (Inst.of Appl. Phys.,Russian Acad. of Sci., 46, Ulyanov St., 603600, Nizhny Novgorod,Russia)
4:50 Theeffect •f thelayer structure ofthe elastic absorbing bottom on the lpAO13. Numerical investigation of ray path stability in the space-frequencydependences of acoustic fields in shallowand deep seas in Mediterranean under the condition of nonstationary signal thefreqoenc•; range 20-500 Hz is studied.The comparison of the experi- receiving. VladimirN. Fokin and MargaritaS. Fokina (Inst. of Appl. mental Jossesdue to soundpropagation in the deep-waterpart of the Phys.,Russian Acad. of Sci. 46, Ulyanov St., 603600, Nizhny Novgorod, Ariantic Ocean at three frequenciesand the resultsof numericalcalcula- Russia) tions by ray programshas shown that the experimentaland calculated lossesmay agree satisfactoryonly if the layer bottomstructure is taken Using the concretec(z) data (c=sound speed,z=depth) obtainedin into account.The numericalstudy in the framesof the approximationof the Mediterraneanduring the THETIS-2 experimenton boardthe ACADE- adiabaticmodes has shown that an absorbinglayer of the geologicalbot- MXCiANSERGœ¾ ¾AVmOV research vessel, the possibilityof ray path identi- tom structureof the BarentsSea influences significantly the characteristics ficationusing nonstationary receiving are numericallyinvestigated. Suffi- of soundfields and enriches the field modespectrum. It is shownthat the cient c(g) data were obtained for numerical simulation of the sound degreeof this effectdepends on the seasonalfluctuations of the sound propagationalong different acoustic routes. Sensitivity of differentrays velocityprofile structure. The relationbetween the type of sedimentsthat pathsto errorscaused by theerroneous determination of depthand distance form bottomlayers and frequencyranges, where the leastlosses due to is analyzed.The possibilityof usingthe data obtainedfrom the research propagationare observed, i.e., optimumpropagation frequencies, is ascer- vesselfor oceanacoustic tomography is discussed. tained.[Work supported by RFFI projectN 94-05-1725-a.]
3250 d. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of Amedca 3250
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp TUESDAY AFTERNOON, 30 MAY 1995 RENAISSANCE EAST, 12:30 TO 5:00 P.M.
SessionlpEA
EngineeringAcoustics and PhysicalAcoustics: Optical Vibration and PressureSensors and Acoustic Measurements and Instrumentation
David A. Brown, Cochair Departmentof Physics,U.S. Naval PostgraduateSchool, Monterey, CA 93943
StephenC. Butler,Cochair Analysisand Technology,Inc., 258 Bank Street,New London, Connecticut06320
Contributed Papers
12:30 tion measurement.This presentationoutlines some of theserequirements for high signalvisibility and describesseveral interesting target surfaces IpEAI. Design of a miniature fiber optic acousticsensor for an undertest, including stainless steel, paints, polymer, and retroreflecting acousticviscometer. Jos6 D. Guevara (Dept.of Mech.Eng., The preparations.Data presented for these surfaces include signal strength (vis- CooperUnion, 51 Astor Pl., New York, NY 10003) and Daniel R. ibility), repeatability,stability, and effectsof surfaceroughenlag and a Raichel (The CooperUnion and the GraduateCtr. of the City Univ. of water environment.Results are interpretedin termsof simplephysical New York) modelswhere possible to better understandpotential specialized target An acousticfiber optic sensorwas designedfor the miniatureversion fabricationfor improvingfuture vibrometer measurement system perfor- of an acousticviscometer under development at The CooperUnion Acous- mance. tic ResearchCenter. The sensorconsists of a singlemode fiber optic cable embeddedin the centerof a 50-mmx50-mmx5 mm compliantpolymer layer. It was notedthat the geometricalversatility of the sensorcould be minimizedfurther, allowing for shorterlengths of sensitizedfiber without sacrificingacoustical sensitivity. A Mach-Zenderintefferometric system is 1:15 employedto detectthe phaseshift of the modulatedoptical signal in the lpEA4. Detection of strain-induced wavelengthshifts in an optical sensitizedfiber. A fiat frequencyresponse in the 200 Hz to 20 kHz was fiber Bragg grating using an over-coupledcoupler. Q. Zhang, D. A. predicted.The lengthof the fiber determinesthe minimumvalue of de- Brown (Phys.Dept., Naval PostgraduateSchool, Monterey, CA 93943 tectablepressure. In additionto immersionin water the sensorhas the and Brown Univ., Providence,RI 02912}, H. Kung, I. Townsend,L. potentialto also withstandimmersion in mildly acidicand alkalinesolu- Reinhart,and T. F. Morse (Brown Univ., Providence,RI 02912) tions. A highly over-coupledfused biconical tapered fiber coupler has been 12:45 used to interrogatethe strain-inducedwavelength shifts from an optical fiber Bragg grating.Both the 95% reflectivefiber gratingsand the over- lpEA2. A fiber optic dual-beam laser Doppler vibrometer for coupledcouplers were fabricatedin our laboratory.The couplerhas a measurement of electrostrictive and piezoactive responseof thin spectralperiod of approximately4 nm at the opticalinterrogation wave- films. F. Guillol, J. Jarzynski (GeorgiaInst. of Technol.Atlanta, GA lengthof 1550 rim. The outputsare processedusing a software-based 30332),and E. Balizer (NSWC, SilverSpring, MD 20903) demodulatorprogrammed in Labview.Results of staticand dynamicin- ducedstrains and sensor prototypes will bepresented. [Work supported in A two-beamlaser Doppler vibrometer (LDV) is described,designed to partby NPSand NSF.] measurethe d33 electromechanical coupling coefficient for electrostrictive andpiezoactive thin films.Optical fiber couplers are usedto splitthe light into multiplebeams and opticalfibers are usedto simultaneouslyillumi- natethe samespot on bothsides of the film. The LDV measuresthe normal displacementon each side and the changein thicknessof the film is 1:30 determinedfrom the algebraicsum of the two LDV signals.It is foundthat large bendingmotion of the film can lead to a significanterror in the IpEAS. Simple intensity type fiber optic vibration sensors and measuredd•3 coefficient.This is illustratedwith datafor PVF2 films and sensorsystems. EdwardF. Cartme (Dept. of Phys.,John Carroll Univ., sourcesof this error are identified.The applicationof the LDV systemto Cleveland, OH 44118) and Vilnis E. Kubulins (Edjewise Sensor measurethe largeelectrostrictive effect in polyurethanefilms is discussed. Products,Inc., Cleveland,OH 44122) [Worksupported by theOffice of NavalResearch.] Researchis continuingon the developmentof simpleintensity type fiberoptic vibration sensors suitable for usein hostileenvironments, such 1:00 as automotiveand aircraftengine cavities. The transructionelement con- sistsof a singleor a pairof opticalfibers mounted on a cantileverreed. The IpEA3. Target visibility measurements: Three-dimensional laser intensityof the optical outputsignal is directly proportionalto the reed vibrometer. JosephVignola, Otis G. Zehl (SFA, Laudover,MD displacementand, therefore, to accelerationat frequencieswell belowthe 20785), and Brian H. Houston (Naval Res. Lab., Washington,DC reedfundamental. Using readily availablematerials an opcratlngtempera- 20375-5000) ture rangeof --40 ø to +225 øC has been achieved.In addition,by em- A three-dimensionallaser vibmmeter has been constructed,tested, and ployingsimple multiplexing techniques, small groups of thesesensors may usedfor simuhaneousmeasurements of threecomponents of inducedtran- be addressedwith a singleoptical source and/or detector. The basicdesign sientmotion of targetsurfaces. Such target surfaces need to satisfya wider of the sensorsand the resultsof extensivelaboratory tests are presentedin rangeof opticalscatter requirements than those for one-dimensionalmo- detail.[Work supported in partby NASA.]
3251 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acouslical Society of America 3251
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 1:45 2:30
lpEA6. Fiber-optic microphone based on combination of IpEA9, Use of a background noise correction. Michael A. Staiano Fabry-Perot interferometry and intensity modulation. Chonghua (StaianoEng., Inc., 1923 StanleyAve., Rockville,MD 20851) Zhou, StephenV. Letchef (Dept. of Phys., Univ. of Rhode Island, Kingston,RI 02881), and Aran Shukla (Univ. of Rhode Island, A correctionscheme has been proposed which consists of repetitive Kingston,RI 02881) measurementsof the source-signal-with-backgroundand hackground noise alonethan the computationof a signalestimate and predictioninterval. A fiber-opticmicrophone based on a combinationof Fabry-Perot in- The procedureassumes that both the sourceof interestand background tefferometryand intensitymodulation is described.The combinationtech- noiseare: uncorrelated.normally distributed, random processes which are nique eliminatesfringe countingambiguity and providesa wide range stationaryover the durationof the measurements.For useful results,the measurementof optical phasechange without any complicatedelectrome- numbersof measurementmust be selectedto provide for a calculated chanicaldevices. The experimentaldata are comparedwith the resultof a confidenceinterval which acceptablycontains the predictionerrors. These theoreticalanalysis. The microphonehas a flat frequencyresponse from 20 requirementsare strongly influencedby the variability of the measured Hz to 10 kHz with a high sensitivityof 1.6 tad/Pa.The dynamicrange is parameters.For relativelylow backgroundnoise situations, the technique morethan 65 dB. The frequencyresponse and sensitivity can be modulated is useful primarily for quantifying expected measurementconfidence by changingthe size and surfacetension of the membrane.The micro- bounds.Application of theprocedure to a fieldmeasurement situation with phonecan be easilyimplemented and can be madevery small.[Work meansource band sound levels ranging approximately from 2 to 15 dBA supportedby NSF.] re: meanbackground band sound levels gave a 99.5%-confidenceupper- boundmargin of 0.3-1.3 dB with 17-19 measurementsper band.
2:45-3:00 Break
IpEA7. Field tests of a high-temperature fiber optic lever 3:00 microphone,Allan J. Zuckerwar(MS 236, NASA LangleyRes. Ctr., lpEA10. Precisionof reference sound source hemianechoicsound Hampton,VA 23681) and FrankW. Cuomo (F. W. CuomoConsulting power calibration using a fixed microphonearray: Relation to ISO Services, East Providence, RI 02914) 6926 revision. Angelo J. Campanella (CampanellaAssoc. & The operatingprinciple of a high-temperaturefiber opticlever micro- ACCULAB, 3201 RidgewoodDr., Columbus,OH 43026) phone(FOLM), ratedat 538 øC (1000 øF) continuousservice, is basedon Reference sound source calibration by the bemianechoicISO 3745 intensitymodulation of light reflectedfrom a vibratingmembrane. The methodallowed a coursearray of l0 measurementmicrophone positions fxequencyresponse of the microphone,calibrated in the laboratoryat am- on a hemisphere.Draft revisionof ISO 6296 providesfor a difficult me- bienttemperature and 538 øC by the electrostaticactuator method, is typi- ridtonalarc constant vertical velocity microphone scan. An improvedarray cally 60-70 kHz. Applicationsto high-temperaturefield testinginclude the of multiple fixed microphonepositions is proposedas an alternateto the thermal acousticfatigue apparatusat Langley ResearchCenter, an ad- meridionalscan method. Bias of the improvedarray was simulatedwith vancedshort takeoff and verticallanding model at Lewis ResearchCenter, Mathcad4.0. Agreementwas predictedto be within0.2 dB up to 4 kHz for theMach 22 heliumtunnel at Langley(ambient temperature only}, interior 10 pointsand up to 8 kHz for 20 points.Experimental results for three mixer-ejectorsurfaces at GE Aircraft Engines,Cincinnati, and a high tem- microphoneposition arrays were comparedto reverberationroom results peratureacoustic impedance tube at Lan•oley.In mostof theseapplications over the limitedfrequency range of 125 to 8000 Hz. The standarddevia- the FOLM madepossible high-temperature, high-frequency acoustic data tionof thedifference was 0.84 to 0.89 dB (0.81dB predicted)for theold to be takenfor the firsttime. Typical test results will be discussed. ISO 3745 array.For an arrayhaving 10 fixedheight difference positions from 0.15R to 0.95R, the standarddeviation was 0.62 dB (0.61 dB pre- dicted).For 20 fixedheights from 0.025R through0.975R the standard deviationwas foundto be 0.63 (0.18 predicted).Calculated results and experimentaltest results,compared with reverberationroom results,will 2:15 be presented. lpEA8. An innovative probe microphone design for use in high-frequencysound field measurements. Seen M. Connelly and 3:15 Linda P. Franzoni (North Carolina State Univ., Ctr. for Sound and Vib., Dept. of Mech. and Aerosp. Eng., P.O. Box 7910, Raleigh, NC lpEAll. Underwaterlinear horn array simulator. StephenC. Butler 27695-7910) and W. JackHughes (Appl. Res. Lab., PennState Univ., P.O. Box 30, StateCollege, PA 16804) There is a need for nonintrusive measurement devices. When the wave- lengthof the soundwave is physicallythe samescale as that of the mi- Sonartransducers with a radiatingface smallerthan one half wave- crophone,its soundpressure cannot be measuredaccurately. Acousticians lengthtend to havea low radiationimpedance load and consequentlya have worked around this difficulty by using smaller microphonesand, narrow transmittingbandwidth. Thus, when the transduceris testedalone, when necessary,using probe tubes with even smallerdiameters attached to themeasured results yield a poorrepresentation of its intendedarray per- small microphones.This needfor very small diameterdevices is especially formance.The objectiveof this researchwas to developa fluid meansto criticalat highfrequency. The useof probetubes introduces another level "pc" load a single sonartransducer element by imposinga condition of complexityto acousticmeasurements. The resonantdynamics of the similarto its intendeduse in an array.A newmethod which accomplishes tube itselfmust be takeninto account.The tubesupports standing waves thisand attains "pc" loadingutilizes a linearendfired waveguide, which thatcause the microphonefrequency response to be very irregular.Typi- forcesa singletransducer to behaveas if it were in an arrayunder "pc" cally, dampingmaterial, such as foam or steelwool is introducedinto the loadingconditions. This is accomplishedby an "underwaterlinear horn probetube to attenuatestanding waves. However, even when damping is arraysimulator" which is composedof a rigid-walledcylindrical tube with successfullyapplied, the responseremains irregular and the dampingma- slotsof equalarea equally spaced along the length of thetube. Acoustical terial resultsin a significantreduction of signal-to-noiseratio. The new circuittheory shows that 85% 0c loadingover an octavebandwidth would conceptis designedto eliminatestanding waves without introducing be achieved.Measurements on a physicalmodel confirm the prediction. dampingin the signal path betweenthe microphoneand the end of the Measured mechanicalQ's of the sonar transducerwithout the horn is 7.5, tube. Therefore,the signal-to-noiseratio will not suffer significantdegra- and with hornis 5, showingthat the loadingeffects of the hornhave been dation, and behaviorwill be consistentfrom probe to probe. achieved.[Work supported by ONR andNUWC, New London,CT.]
3252 J. Acoust.Soc. Am., Vol. 97, No.5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3252
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp IpEAI2. Abstract withdrawn. mathematicallyidentical and producesimilar experimental results. Com- parisonof theimpedance tube and free-field measurements suggest that the latterapproach produces more reliable results. However, due to practical limitationsof the source/receivergeometry free-field measurements at low frequenciesare morecomplicated in thatthe planewave assumptionis not valid.
4:15
IpEA16. Panel responseto jet noise under near sonic conditions. CharlesC. Fenno,It. (NASA LangleyRes. Ctr., Hampton,VA 23681), Alvin Bayliss (NorthwesternUniv., Evanston,IL 60208}, and Lucio Maestrello (NASA LangleyRes. Ctr., Hampton, VA 23681}
The problemof the responseof an arrayof flexibleaircraft-type panels excitedby noisefrom a jet undernear sonic conditions from a converging 3:30 nozzle is numericallystudied. The problemis computedby solvingthe Eulerequations for the unsteadyfield in thejet, fully coupledto equations IpEAI3. Measurement of acoustic properties of materials at low describingthe panel motion.Computations of the far-field sound,panel frequenciesin a water-filled tube. Debra M. Kenneyand Peter H. response,and panel radiation are presented. The effectof nozzlegeometry Rogers (GeorgiaInsl. of Techno!.,School of Mech.Eng., Atlanta, GA on the radiatedsound and jet instabilitiesis studied.In addition,the rela- 30332) tionshipbetween panel location, relative to thejet exit,and panel response is determined.The computationsimulates the developmentof largeam- Two of the traditionalmethods for measuringthe complexreflection plitude,slowly propagatinginstability waves in the jet which act as addi- coefficientof a material,the standing-wave tube method and the pulse tube tionalsources of sound.Thus the computationallows for directcomputa- method,each have shortcomings when the measurementsare to be madein tion of the naturalsources of jet noise,as well as the propagationof the a water-filledtube at low frequencies.An acousticimpedance tube has resultingjet noise.The resultsdemonstrate large disturbances in the vicin- beendesigned to overcomethese shortcomings. The designuses a transient ity of the convergingnozzle which act as additionalsources of sound.The incidentsignal as opposed to a cw signalin orderto minimizethe problem panelresponse is concenlratedin progressivelylower frequenciesas dis- of vibrationsin the tubewall. it alsouses a dualsensor system [D. Gutek- tance from the jet exit increases. ingand K. Karcher,Trans. ASME: I. Vib.Acoust. Stress Reliability Design 106,393-396 (1984}]to separatethe incidentsignal from the reflected signalwithout them being temporally separated. Active impedance control 4:30 at theend of thetube opposite from the samples reduces the reflection from lpEAIY. Acoustic detection of jet aircraft. Brian G. Ferguson thatend. The tubehas been designed so thatambient pressure and tem- (DefenceSci. and Technol. Organisation, P.O. Box44, Pyrmont,Australia peraturecan be controlledduring measurements to simulatean oceanen- 2009) vironment.The analyticdesign of the tubeand preliminary experimental resultswill be presented.[Work supported by ONR andNSF.] A passivebroadband acoustic technique is describedthat detectsthe transitof a subsonicjet aircraft.The outputsfrom a pair of spattally
3:45 separatedmicrophones are cross-correlated in three overlapping frequency bands.The time lag that correspondsto the maximumvalue of the cross- lpEAI4. Wind turbulence spectra for heights from 2 to 32 m correlogramis extractedfor eachof the threebands every second.Coin- measured during the JAPE experiment. Scott D. Hansen and cidencedetection of thistime lag informationresults in thedetection of the KennethE. Gilbert (Appl. Res. Lab. and the GraduateProgram in jet transitwith a negligiblefalse alarm rate. The detectionrange is ex- Acoust.,Penn State Univ., P.O. Box 30, StateCollege, PA 16804) tendedby applyingthe technique to thebeamformed outputs from a pairof microphonearrays. The resultsof applyingthe techniqueto realdata from During the Joint AcousticPropagation Experiment conducted at the 25 jet transitsare presented. White SandsMissile Rangein the summerof 1991,wind speedmeasure- mentswere madeon two 32-m-hightowers. The vectorwind speedwas 4:45 sampledcontinuously at 10 Hz for periodsof up to 2 h. The powerspectra for wind speedfluctuations (turbulence spectra} have been computed at lpEAI8. Measurementof the distortion level of a loudspeakerusing heightsof 2, 4, 8, 16, and32 m. For a givensample length, the spectraare an adaptive filter algorithm in a reverberation and noisy nearlythe sameat all heights.At all heights,however, there is significant environment. Chun-Duck Kim (Dept. of Elec. Eng., Natl. Fisheries sensitivityto the lengthof the samplingperiod. The meteorologicalreasons Univ. of Pusan,Pusan, Korea}, and Suk-Kun Jee (KunsanNatl. Univ., for the sensitivityare discussed. In addition,selected acoustic propagation Kunsan,Korea), and Abe Masato (TohokuUniv., Sendai, Japan) calculationsarc presentedto demonstratethe influenceof the different spectraon acousticpropagation. [Work supported by theArmy Research This paper describesa methodto measurethe distortionlevel of a Laboratory.] loudspeakerand an amplifierusing a LMS (least-meansquare) adaptive filter.The acousticapparatus checks the distortionlevel and the residual noiseusing a bandpassfilter havinga sharpcut-off frequency characteristic 4:00 and a sinusoidaloscillator. The abovebandpass filter, however, is expen- sive and hasa long responsecharacteristic. It is impossibleto checkeach IpEA15. Application of cardtold beamforming in both impedance harmonic distortion. Also, to cheek the harmonic distortion of a loud- tube and free-field measurementsof ground impedance. David C. Swansonand EdwardManiet (Appl. Res.Lab., PennState Univ., P.O. speakerin a roomwith ambientnoise, the experiment room needs to be an Box 30, StateCollege, PA 16804) anechoicchamber. On the otherhand, the proposedmethod offers an easy way to measurethe specifiedharmonic distortion level with a snmll Measurementsof the specificacoustic impedance of groundcovered by amount of hardware.Moreover, this method is not affected by ambient institutional grass were performed using both a card•oid beamforming noise which has no correlationwith Ihe test .qgnal.The measurementcan methodand the established transfer function method [J. Y. Chungand D. be carriedout in a noisy environment.The systemconsists of a 32-bit A. Blaser,I. Acoust.Soc. Am. 68, 907-921 (1980)]. The cardioidmethod DSP96002,2ch of 16-bitanalog to digitalconverter, and a 5th Chebyshev steersa beampatternto separatethe incidentand reflectedwaves. Both filter with a 50 kHz samplingfrequency. The effectivenessof the proposed methodswere appliedto impedancetube and free-field measurements. methodconfirmed by experimentsusing a loudspeakercarried out in a With propercalibration, the cardioidand transferfunction methods are room with ambient noise.
3253 J. Acousl. Soc. Am., VoL 97, No. 5, Pt. 2, May 1995 129th Meeting: AcousticalSociety of America 3253
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp TUESDAY AFTERNOON, 30 MAY 1995 MEETING ROOM 2, 1:00 TO 4:45 P.M.
SessionlpNS
Noise: Active Noise Control and Duct Acoustics
Susan K. Numrich, Chair Naval ResearchLaboratory, Code 5580, Washington,DC 20375-5000
ContributedPapers
1:00 1:30
lpNSI. Active control of broadband random noise using energy IpNS3. Active control of sound transmission through a thin metal densitycontrol. YoungC. Park and ScottD. Sommerfeldt(Appl. Res. plate. Xianqi Bao, VasuudaraV. Varadan,and Vijay K. Varadan (Dept. Lab. and GraduateProgram in Acoust., Penn State Univ., P.O. Box 30, of Eng. Set. andMech., PennState Univ., UniversityPark, PA 16802) StateCollege, PA 16804) The performanceof active soundisolation by usinga piezoelectric sensorand an actuatoron a thin plateis investigatedexperimentally. In the Previous work on active noise control in enclosures has indicated that experiment,the aluminumplate covers an openingof an acousticenclo- onecan often achieve improved global attenuation of deterministicsignals sure, where a sound source is located. The outside acoustic field is mea- by minimizingthe acousticenergy density, rather than the squaredpres- suredby an 11-elementmicrophone array, which scanson a surfaceof a sure.The purposeof thiswork is to presentnumerical results that compare hemisphere.The isolationperformance of the originalplate is poorat it• the globalattenuation of broadbandnoise achieved by minimizingenergy resonancefrequencies. The soundtransmission from insideto outsideof densitywith the attenuationachieved by minimizingsquared pressure in a the enclosureis activelycontrolled by a one-sensorone-actuator control one-dimensionalenclosure. A theoreticalapproach based on the frequency systemwhich minimizesthe outputof the on-platesensor. Global reduc- domainenables one to establishthe basicphysical limitations of active tionsof 15-20 dB are achievedat the first threeresonance frequencies. noisecontrol systems. However, this approachcannot necessarily be ap- plied when controllinga broadbandrandom noise, since it often yields 1:45 optimal control solutionsthat are noncausalin the time domain, even thoughsuch a frequencydomain approach is entirelysatisfactory for de- IpNS4. Near-field acousticholography for enclosureswith unknown terministicsignals. Analyses reported here are undertakenin the time do- Green's functions. Kelly Q. Kay (Virginia Polytech.lust. & State main in a mannerthat yieldsthe form of the causallyconstrained optimal Univ. Virginia Consortiumof Eng. and Sci. Universities,2713-D controller.Numerical results are presentedto predictthe performanceof MegruderBlvd., Hampton,VA 23666), Chris R. Fuller (x,r•rginia the activenoise control system designed to controla broadbandnoise, and Polytech.Inst. and State Univ., Blacksburg,VA 24061), and Karen H. to indicatethe improvedglobal attenuationof broadbandnoise that can be Lyle (U.S.Army Vehicle Structures Directorate, NASA LangleyRes. Ctr., achievedby minimizingenergy density, rather than squaredpressure. Hampton,VA 23681)
A methodfor predictingthe acousticfield in acousticallycomplex cavitiesis developedbased upon currentnear-field acoustic holography (NAH) techniques.Current NAH methodsmake use of analyticalGreen's
1:15 functionsto generatepredictions of globalacoustic fields. For this reason, NAH is easilyapplied to generatepredictions in free fields,and in cavities lpNS2. Multichannel block adaptive filters for real-time, with simplegeometries and uniformboundary impedances. For acousti- nonparametric identification of time-varying plants. William C. cally complexcavities, however, the absenceof a known analytical Nowlin,Gary S. Guthart,and Gregory K. Toth (Appl.Control & Signal Green's function, renderscurrent NAH methodseither not soivable, or in Process.Group, SRI International,Menlo Park,CA 94025) caseswhere approximate Green's functions are used,not accurate.The methodrequires no prior knowledgeof the acousticallycomplex cavity's Many real-worldapplications of activenoise control are characterized Green'sfunction. As well, no approximationsabout the boundarycondi- tions are required.Instead, the methodtakes advantage of the discrete by transferfunctions that vary significantlyand unpredictably.The con- natureof NAH predictions,in conjunctionwith an initial measurementof troller'stransfer function models must adapt to thesevariations. Presented a cavitiesacoustic pressure field, to generatea cavity specificdiscrete here is a classof adaptivefilters that accomplishquasiperiodic system Green'sfunction. Computational and experimentalresults will be pre- identificationupdates for feedforwardcontrol by usingblocks of input- sentedalong with a detailedexplanation of themethod. [Work supported output histories.The algorithmsform a one-dimensionalfamily linking by NASA LangleyResearch Center.] normalizedLMS adaptivefilters and optimalWiener filters,and are termed "block projection"algorithms. The systemidentification proceeds nonin- vasively,producing nonparametric (FIR) impulseresponses. The multi- channelgeneralization and applicationof thesealgorithms to systemiden- tification,as presentedhere, is novel. Considerationsare describedthat IpNSS. Principal componentanalysis applied to the active control of arise from the algorithms'implementation in the contextof systemiden- turbofan inlet no'se. Ran Cabell (VirginiaPolytech. Inst. and State tification;in particular,the proper weighting of inputand output data pairs Univ.-Virginia Consortiumof Eng. and Set. Universities,2713-D is discussed.The resulting multichannelcontrol algorithms have been Magruder Blvd., Hampton, VA 23666) and Chris Fuller (Virginia Polytech.Inst. and StateUniv., Blacksburg,VA 24061) implementedsuccessfully for quielingof a compactdislributed source in an anechoicenvironment, and for local quietingof a diffusefield in a An analytical study of the active control of fan noise in a turbofan reverberantroom. In bothcases, error microphones could be movedabout, enginewith wall-mountedacoustic sources is described.The transferfunc- providinga "mobilequiet zone," and performancewas obtained for band- tionsbetween the acousticsources and microphonesoutside the ductare widthsexceeding a decade. decomposedinto principal components (PCs). The activecontrol problem
3254 J. Acoust.Soc. Am., Vol. 97, No.5, Pt.2, May1995 129thMeeting: Acoustical Society of Amedca 3254
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp is then solved using a subsetof the principal components.The subset informationregarding the sourcecharacteristics. Comparisons are made consistsof PCsthat are statisticallysignificant for accuratelymodeling the betweennoise from a singleaircraft both inside and outsidea hushhouse. primaryradiated noise. The resultingelimination of certainPCs is a math- Sourcelocation calculations indicate that low-frequencynoise originates ematicallyefficient way to optimallyreduce the numberof channelsof from a regionnear the trailingedge of thejet exhaustdeflector. Coherence control.In certaincases it canbe shownthat the PCs describe the radiating betweenselected near-field and far-field sensors is foundto be sufficiently modesof the co,ntrolsystem. This providessubstantial insight into the highto,warrant experimental investigation of theactive reduction of noise mechanismsof control,and can be usedin thecontroller to derivespecific from a full scalehush house, using feedforward control techniques, fol- modesto the exclusionof all othermodes. [Work supported by NASA lowingon fromthe small scale hush house experiments described by J.P. LangleyResearch Center.] Smithet al. [J.Acoust. Soc. Am. 96, 3332(A)(1994)]. [Work sponsored by the U.S. Air Force.] 2:15
lpNS6. Optimal design of enclosuresfor active noise control and isolation. VasundaraV. Varadan,Jaehwan Kim, and Vijay K. Varadan (Res.Ctr. for the Eng. of Electron.and Acoust.Mater., Dept. of Eng. Sci. 3:15 & Mech.,Penn State Univ., University Park, PA 16802)
An optimaldesign technique is usedto find the optimalconditions for lpNS9. Active control of acoustic intensity in a duct. Karl M. severalparameters of an enclosure to reducei•he noise radiated from an Reichard,David C. Swanson,and Scott M. Hirsch (Appl.Res. Lab., Penn internalsource. Design variables in the optimizationprocedure are the size StateUniv., P.O. Box 30, StateCollege, PA 16804) and thickness of the enclosure, size and thickness of actuators, the location of actuators,and the appliedvoltage on the actuators.The objectivefunc- A frequency-domainimplementation of the filtered-xalgorithm is used tion in optimaldesign is the total radiatedsound power at far field. The to activelycontrol acoustic intensity in a duct. The frequency-domain practicallimits of the designvariables are takenas constraints.The acous- filtemd-x algorithmuses FFT's of the necessarysignals to computethe tic field acts as a distributed load on the walls of the enclosure. A 3-D finite transferfunction of the optimalcontrol filter. A versionof the algorithm element model is used to model the walls and the PZT actuators. With an hasbeen adapted to useacoustic intensity, computed from the crossspec- appliedvoltage on the actuatorsand with acousticpressure loading, the trum from two pressuremicrophones, as the errorsignal. The resultsof velocitydistribution on the outsideof the wallscan be foundby solvingthe experimentsconducted in a duct are presentedwhich demonstratethe finiteelement equations. These are usedin the Helmholtzintegral repre- effectsof measurementerror and control source configuration on controller sentationto computethe radiatedsound field to the exteriorof the enclo- performance. sure.The designis performedat a singlefrequency which may represent the dominantfrequency in the noisespectrum. By comparingthe initial designand the optimaldesign results, a noisereduction of 12-18 dB has been achieved. 3:30 2:30 IpNS10. Insertionloss studies of a baffle-simpleexpansion chamber lpNS7. Attenuationof broadbandnoise in a reverberantroom using system. P. Xiao andM. G. Prasad (Noiseand Vibration Control Lab., a multichannelactive noisecontrol system. Gary S. Guthart,William Dept. of Mech. Eng., StevensInst. of Technol.,Castle Point on the C. Nowlin,and Gregory K. Toth (Appl.Control & SignalProcess. Group, Hudson,Hoboken, NJ 07030) SRI International,Menlo Park, CA 94025)
Active noisecontrol (ANC) is often discussedin the contextof reduc- Insertionloss (IL) is the differenceof soundpressure levels measured ing noisein vehicles.The acousticreverberation of typicalvehicle cabins at a referencepoint without and with a mufflerin a ductsystem. Thus, IL makesthe applicationof ANC to quietinginterior noise a stiff challenge. describesthe acousticalperformance of the wholesystem which includes While someANC approachestake advantageof the modalstructure of source,muffler, and tail pipe.IL studiesof a simpleexpansion chamber has reverberantenclosures to providereduction throughout the enclosure, these beenreported in theliterature. However, them are not many IL studiesof approachesbecome infeasible for manyfrequency bands of practicalin- complicatedgeometries in a mufflerfrom a systemdesign point of view. terestbecause of increasingmodal density with increasingfrequency. For This studyreports both experimental and analytical work on the influence high-bandwidth,diffuse fields, noise reductionis achievedlocally by of a baffleon IL of a simpleexpansion chamber. The hole diameterand specifyinga quietzone within the enclosure.Experimental results for locationof the bafflerare the parametersof thisstudy. An Altecelectroa- broadband,local quietingin a diffusefield usinga multichannelANC cousticdriver is usedas a sourcefor experimentalwork conductedin an systemare presented. The mverberantenclosure is an ordinaryroom, mea- anechoicchamber. The analyticalwork is carriedout usingthe boundary suringapproximately 1.4 mx2.4 mX2.4 m andcontaining a seatedopera- elementmethod. The resultsindicate a significantinfluence (due to the tor with six microphonesdefining the quietzone near the operator'sears. interactionof sourceand load) on the insertionloss. The controlsystem uses a singlereference signal and two errorchannels to drivefour control speakers. An averageof 20-dB reductionin soundpros- surelevel is foundat the quiet-zonemicrophones for the frequencyrange 50 to 1000Hz. Theseresults demonstrate the viabilityof real-time,mul- tichannelANC for locally attenuatingrandom noise in diffuse acoustic 3:45 fields. lpNSll. Reflectionof higher-ordermodes at the end of rectangular 2:45-3:00 Break ducts. RalphT. Muehleisenand David C. Swanson(Appl. Res. Lab., PennState Univ., UniversityPark, PA 16802) 3:00 Reflectioncoefficients for higher-ordermodes impinging on the ends lpNS8. Experimentalinvestigation of low-frequencynoise from jet of finiterectangular ducts were predicted and measured. The resultsshow enginetest cells. RobertG. Gibson (Wyle Labs.,2001 JeffersonDavis couplingbetween propagating and evanescent modes. Expressions for the Hwy., Ste.701, Arlington,VA 22202) reflectioncoefficients in terms of modal coefficientsand modal imped- Low-fmquencynoise emission from facilities designed for the ground anceshave beendeveloped. Radiation patterns were predictedfrom the runuptesting of jet enginescan be a sourceof annoyanceto communities knowledgeof the couplingcoefficients. It was foundthat higher-order nearmilitary air bases.Noise measurements, using arrays of microphones modesradiate most of theirenergy off towardsthe sidesand lessstraight and accelerometersat a numberof U.S. Air Force hush houses,provide aheadthan the planewave mode.
3255 J. Acoust.Soc. Am., Vol.97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3255
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 4:00 theBragg condition resulting in a strongstopband interaction. The problem is attackedusing the perturbation method of multiplescales, leading to the 1pNS12. Acoustical studies of a duct system using a power flow derivationof thecoupled-mode equations. The performanceof the ductas model. Woo-sungKim (HDD DesignEng., SamsungElectronics Co., a waveattenuator is presentedin terms'ofthe reflection coefficient or the Ltd., 416, Maetan-3Dong,Paldal-Gu, Suwon City, Kyungki-Do,Korea) transmission•oss factor. Due to the natureof the dispersiohcurves of the and M.G. Prasad (StevensInst. of Technol.,Hoboken, NJ 07030) cylindricalduct, many modescould sharethe same stopband.Hence, a Any ductsystem from an acousticalpoint of view can be modeledas multi-modeacoustic filter could be designedover a certainfrequency a souree-loadsystem. The powerflow analysisin a source-loadsystem is band.This theoreticalstudy might provide a basisfor designconcepts of importantfor a system'sacoustical design. The present work describes the acoustic silencers. developmentof a powerflow modelutilizing the source and load imped- ancesas parameters.Also, the sourceis describedin termsof its power 4:30 ratherthan the pressureor the volumevelocity. The studyincludes both analyticaland experimental work. The analyticalwork deals with the de- 1pNS14. Studies of source-load interaction in a duct system using velopmentof expressionsfor powerflow in the system.The experimental acousticnoise synthesis. AnilkumarBhate and M. G. Prasad (Noise work is carriedout usingan Altec electroacousticdriver as the sourceand and Vib. Control Lab., Dept. of Mech. Eng., StevensInst. of Technol., variousducts as theloads. The systemperformance is evaluatedusing the Castle Point on the Hudson,Hoboken, NJ 07030) powerflow modelfor variousloads. The studyhas yieldedgood results Acousticnoise synthesis (ANS) for duct systemswas first developed validatingthe powerflow modelfor ductsystems. by the authors(M. G. Prasadand T. V. Ananthapadmanabha,INTER- NOISE 89 Proceedings)based on the principlesof speechsynthesis using 4:15 a source-filtermodel. The ANS allows the designerof a duct systemto simulatethe perceptualquality of the acousticaloutput of the system.The lpNSI3. A multi-mode acoustic filter based on Bragg resonance. MuhammadA. Hawwa, Chris R. Fuller, and RicardoA. Burdisso (Vib. ANS is basedon the transferfunction which is evaluatedusing the known geometryof theduct system. The present work describes the application of andAcoust. Labs., Dept. of Mech.Eng., Virginia Polytech. Inst. and State ANS to studythe interactionbetween source and load on the perceptual Univ.,Blacksburg, VA 24061-0238) qualityof a duct systemacoustic butput. An electroacousticdriver as a A unifiedmethod is proposedto suppressduct acoustic waves. Accord- sourceand ductsof variouslengths are used as loads.Good resultsare ing to this method,a circularcylindrical duct is designedto havea geo- obtainedwhich validate the applicationof acousticnoise synthesis in de- metricperiodicity at itswall in orderto actas a wavefilter. The filteraction signof ductsystems with emphasison the perceptualquality and subjec- of the periodicrigid wall is basedon the modecoupling occurring under tive evaluation.
TUESDAY AFTERNOON, 30 MAY 1995 RENAISSANCE WEST B, 1:00 TO 5:00 P.M.
SessionlpPA
PhysicalAcoustics and Noise: Sonic Boom
David T. Blackstock, Cochair AppliedResearch Laboratories and MechanicalEngineering Department, University of Texasat Austin,P.O. Box 8029, Austin, Texas 78713-8029
Allan D. Pierce, Cochair Departmentof Aerospaceand MechanicalEngineering, Boston University, 110 CummingtonStreet, Boston, Massachusetts 02215
Invited Papers
1:00
IpPAI. Current strategiesin sonic-boomresearch. ChristineM. Darden (NASA LangleyRes. Ctr., Hampton,VA 23665)
DuringNASA's high-speedresearch program, a renewedemphasis has been placed on understandingand reducingthe sonicboom generatedby an airplaneduring flight at speedsfaster than the speedof sound.When the currentprogram was initiatedin 1990, a three-prongedapproach was instituted: (1) humanacceptabilities studies; (2} atmosphericpropagation studies; and (3) airplanedesign andoperation studies. Original goals were to usespecial design and operation techniques to reduce the sonic b•om to levelswhich wouldbe acceptablefor eitherunrestricted overland flight or overlandflight through low-populated corridors. Recent human response studieshave indicated that sonicbooms are muchmore disturbing than continuous noise sources such as enginesaround airports; thus any commercialoverland supersonic flight is highly unlikely within the near future.These conclusions have resultedin a redirection of the sonic-boomprogram. This talk will discusscurrent efforts at sonic-boomsoftening (small design changes), continuing efforts to understandthe impactof the atmosphereon the risetime of the sonicboom signature, and strategies to understandwhat impact,if any, the sonicboom has on marine life.
3256 J. Acoust.Soc. Am., VoL 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of Amedca 3256
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lpPA2.Studies of sonicbooms with seismic networks. Bradford Sturtevant, Joseph E. Cates(Graduate Aeronaut. Labs., California Inst. of Technol.,Caltech 301-46, Pasadena,CA 91125), and Hiroo Kanamori (CaliforniaInst. of Technol..Pasadena, CA 91125)
Seismographsare sufficiently sensitive to detect ground motions induced by atmosphericpressure waves, so seismic networks have thepotential to monitorsonic booms over large areas of theUnited States. They are especially well suited for the analysis of long-range sonic-boompropagation. Ground motion or displacementdata provide accurate arrival times and useful estimates of waveamplitude andwaveform. The instrumentationis most sensitive to the disturbanceproduced by the •u'rivalof sonicbooms at the measuring station,thus serving as sonic-boomevent recorders, but seismographshave also detected seismic waves remotely generated by anomalouscoupling of sonicboom into soil. Direct and indirect sonic booms from aircraft operations are routinely detected by the Sou•ernCalifornia Seismic Network which consists of 250seismic stations covering 50 000sq km. Indirect booms from space shuttle landingshas been observed at ranges of hundredsof kilometers from the flight path. Data from the network identified "mystery booms"heard in 1992-93to be long-rangeindirect sonic booms from offshore operations. Sonic booms generated by spaceshuttle teentryat Mach 20 and by meteoritic entries into the atmosphere have been detected by seismic networks in theNorthwest and Canada.
1:40
IpPA3. The predictionof sonic-boomdistortion using a scatteringcenter based calculation. RichardRespet and Henry E. Bass(Dept. of Phys.and Astron., Natl. Ctr. for Phys.Acoust., Univ. of Mississippi,University, MS 38677) A numericalscattering technique has been developed to calculatethe effectof turbulenceon soundpropagation. This technique resolvesthe atmosphere into discrete "turbules," calculates the scattered field from each turbule using the Born approximation, then sumsall thecontributions to form the scatteredwaveform. The effectof single"turbules" of differentscales will be discussed.This techniquehas been applied to modelthe atmosphere and the propagation oi• sonic booms through the planetary boundary layer during theJAPE-2'tests at White Sands. Good agreement was achieved. The limitations and planned improvements will bedescribed. [Work supporteelby NASALangley Research Center.]
2:00
lpPA4.Effects of atmosphericstratification on sonic-boom propagation. Robin O. Cleveland(Appl. Res. Labs., P.O. Box 8029, Austin,TX 78713-8029) Sonic-boompropagation is affected by stratification,geometrical spreading, nonlinear distortion, absorption and dispersion, and turbulence.Stressed in thispaper is stratification,in particular its indirect effect on distortion and absorption. The stratification of the densityand sound speed leads to refractionand impedance variation, which play a majorrole in determiningthe amplitude of the waveformon the ground. Stratification, and associated spreading, can also control the amount of nonlineardistortion a sonic boom suffers.In extremecases the amount of nonlinea•distortion isfinite--a phenomenon known as waveform freezing. Analysis shows that for aircraftin the lower20 km of the atmospherewaveform freezing does not occur.Through their dependence on temperature, pressure,and humidity, absorption and dispersion arealso stratified. A new time domain algorithm, based on a Burgers-typeequation, wasdeveloped toanalyze the effect of thestratification of absorption [J.Acoust. Soc. Am. 96, 3275 (A) (1994)].The code is used to predictsonic-boom waveforms onthe ground. It isdemonstrated thatsonic-boom shocks are affected not just by local absorption but alsoby absorptionalong path for thepast 5 km or so.[Work supported by•NASA.]
2:20 '•"
lpPAS.USAF flight test investigation of focused sonic booms. Micah Downing (USAF Armstrong Lab., 2610 Seventh St., Wright-PattersonAFB, OH 45433) and NoelZamot (USAF TPS, Edwards AFB, CA 93524) In April1994, the USAF Armstrong Laboratory incooperation with USAF Test Pilot School conducted a measurement study of controlledfocus booms generated bysupersonic maneuvers. The objective ofthis•study was to collect focus and post-focus booms and toassess the ability of aircrewstocontrol the placement of the focal region during basic maneuvers. Forty-nine flights were performed andincluded level linear acceleration, level turn, accelerating dives, and climbout/pushover maneuvers. Sonic booms were collected byup to 25boom event analyzer recorders (BEARs) placed in a 13000-ft linear array. The BEAR units were spaced 500 to 2000 ft apartwith the denser spacing at theexpected focal region. This spacing was chosen to evaluatethe thickness of both the focal and post-focalregions. Of the49 flights,a focus boom was successfully placed within the array 35 times which demonstrated theability to placecontrolled focus booms. This ability of theaircrew can be employed to avoidcollateral damage to noisesensitive receptors. Alongwith capturing focus U waves,complex N-U signatureswere recorded atdistances away from the foci. Turbulent conditions hada defoeusingeffect, resulting in smallermaximum overpressures.
2:40
lpPA6.The theoretical and computational basis of focusedsonic booms. Kenneth J.Plotkin (Wyle Labs., 2001 Jefferson Davis Hwy.,Suite 701, Arlington, VA 22202) Forthe past 20 years sonic-boom signatures infocus "superboom" regions have been computed using a methodbased on a scaling lawby Guiraud [J. Mech. 4, 215-267(1965)] and a numericsolution by Gill [Ph.D. thesis, Cornell University (1974)]. The method recognizesthat the smooth caustic case treated by Guiraud and Gill is by far the most common focusing situation, and that smooth causticscaused by aircraft accelerations andturns and by atmospheric gradients are topologically similar. Gill's numeric result for a shockmay thus be treated as a canonicalresult, and scaled to arbitrarysituations by Guiraud'ssimilitude. The process has been
3257 J. Acoust.Soc. Am., Vol. 97, No.5, Pt.2, May1995 129thMeeting: Acoustical Society of America 3257
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp incorporatedinto an existing sonic-boom program. When a focusis detected,the program fits the solution by (a) computingray and causticcurvatures required by the theory,(b) determininga matchingposition consistent with Gill's boundaryconditions, and (c) applyingthe scaled Gill solutionto eachshock. The computational requirements of this process are reviewed, together with empirical supportfor the results.
3:00
lpPA7.Effects of sonicbooms on animals:Past history and future directions. Ann E. Bowles (Hubbs-SeaWorld Res. Inst., 2595South Shores Rd., San Diego, CA 92109) Modelsdeveloped to describeand mitigate damage to humanhearing after sonic-boom exposure can be appliedto a widerange of species.If humansand laboratoryanimals are poor modelsfor a speciesof concern,or if intensefocused sonic booms are anticipated,experimental assessments will be needed.Although attenuation across interfaces (air-water and air-soil) will protect manyaquatic and fossorial species, attenuation may not protect individuals near the interface if boundaryphenomena like evanescent energyare found to be important.Panic reactions are a likelierhazard for animals,at leastin air.Damage in panicsis predictedbest by species-typicalavoidance behaviors (e.g., panic flight), sound exposure level (after appropriate weighting), and previous experience with impulsiveman-made noise. Dose-effect models have not been developed because controlled experimental studies with booms at levelsup to 150dB (peakfiat SPL) havefailed to elicit panics.However, widespread concern continues because there are circum- stantialaccounts of catastrophicdamages, notably the "SootyTern Incident." Controlled studies of habituationusing initially naive animalsare r/ceded to developdose-effect models for damagingresponses. Effects of impulse-inducedfrights on (1) gametogenesis, conception,and early embryonic development, (2) parentalcare, (3) activity,and (4) habitatuse should be investigatedaswell.
3:20-3:30 Break
ContributedPapers
3:30 4:00
IpPAS. Sonicboom from the Titan IV spacelaunch vehicle launched lpPA10. Seasonalacoustic propagation effect. Wayne R. Lundberg from Vandenberg Air Force Base. Jon K. Francine find Brent S. (3312Braddock St., Kettering,OH 45420) Stewart(HUbbs-Sea World Res. Inst., 2595 lngraham St., San Diego, CA Seasonalvariations in wind and temperaturegradients are known to 92109) influencethe propagationof aircraft noise and sonicbooms. This paper The sonicboom generated by a Titan IV spacelaunch vehicle launched examinesl•redictive techniques incurrent use for potential refinement and on 7 November 1991 was recordedat two locationson San Miguel Island, applicationto seasonalenvironmental impact statements.The effectsof California. A Bmel & Kjaer microphonecarder systemrecorded the over- seasonallyaveraged refractive atmospheres were studied using sonic-boom pressurenear a haul-outsite for about40 000 pinnipeds(seals and sea propagationmodels which includerefractive effects. The atmosphericen- lions);a boomevent analysis recorder (BEAR) wasplaced under the pre- vironment was chosen to be that near Edwards Air Force Base where sonic dictedfocal region.The boomreached the pinnipedsite 4 rain and 38 s boomsare knownto affectthe public. Sonic-boom carpet predictions for a after launch. It was neither an N nor a U wave at either site; rather, it had representativeflight of an F-I 11 at Mach 1.3 and I 0 000 ft abovemean sea severaldistinct positive peaks, which indicates that the focal region was level weredocumented. The effectof suchatmospheres on predictednoise upmngeof therecording sites. The firstand fourth positive peaks were 853 exposurecontours due to a real-worldmix of supersonicflights was cal- ms apart.At the pinnipedsite, most of the boom'senergy was at low culatedusing appropriate adjustments to the CORBOOM model.Two dis- frequencies(ca<500 Hz), as indicatedby the 46-dB differencebetween tinct atmosphericaveraging techniques were appliedfor seasonaland an- the 124-dBunweighted sound exposure level (SEL) and the 78 dB nual comparisons.The resultingsingle-event and sonic-boomexposure A-weightedSEL. The peak overpressurerecorded near the pinnipedswas predictionswere compared to eachother and to predictionsobtained using 64.1 Pa (!.34 psf; 130dB peakSPL). The BEAR systemrecorded a peak the U.S. StandardDay Atmosphereand the Annual Reference Atmosphere overpressureof 90.5 Pa (1.89 psf; 133dB peakSPL). Empirical tests of for EdwardsAFB. The resultsshow the potentialbenefit of conducting predictivemodels for focal regionsand descriptionsof the frequencychar- seasonalacoustic predictions in forecastingthe effectswhich low-altitude acteristicsof focusedbooms are still neededto evaluatethe potentialrisks aircraftflight operationshave on the public. to wildlife from these booms.
4:15 3:45 lpPAll. Application of model experiment data to test sonic-boom lpPA9. Sonic-boomnoise penetration into the ocean: 1995 update. propagationmodels. Bart Lipkens (MacroSonix,1054 Technology VictorW. Sparrow'(Grad. Prog. Acoust., Penn State Univ., 157Hammond Park Dr., Glen Allen, VA 23060) Bldg., UniversityPark, PA 16802) Model experimentsare successfulin simulatingthe propagationof Thla talk is an up•lat• to a pr•;vioualygiven pnzasntation[J. Acoust. some booms tttrougttthe atmosphericturbulent boundary layer. In the Sec.Am. 94, 1850-1851(A) (1993)] in whicha first-passmodel for the modelexperiment spark-produced N waves propagate across the turbulent penetrationof sonicboom noise into the oceanwas described.Since that flow field of a plane jet. The N waves are measuredby a wide band presentationwas given,a numberof refinementsto the theoryhave been condensermicrophone andthe turbulence is measured by,hot-wire an- identified,the primaryof which is the effect of aircraftMach numberon emometry.The resultsfrom the modelexperiment, pressure waveforms the durationof the sonicboom. The generaltrend for airemft flying at a and turbulence characteristics, are used to test various sonic-boom models fixed altitude is that the evanescent acoustic wave underwater due to a for propagationthrough turbulence. Both waveformdistortion models and sonicboom penetrates more deeply for increasedaircraft speeds [J. Acoust. risetime prediction models are tested. Only Pierce'smodel [A.D. Pierce, Soc.Am. 97, 159-162(1995)]. Other refinements currently under devel- J. Acoust.Sec. Am. 49, 906-924 (1971)]based on thewavefront folding opmentinclude appropriate initial models for sound level decay a}'a func- mechanismat a causticyields a fairlyaccurate prediction for the risetime tion of depth and for focusingand defocusingof the penetratingsonic of the meanwaveform after propagationthrough the turbulence.Results boom noise by "frozen" sinusoidaland trocboidalocean surfacewaves. fromother models are notconfirmed by the modelexperiment data. [Work [Worksupported by NASAResearch Grant NAG-I-1638.] supportedby NASA Langley.'[
3258 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3258
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IpPAI2. On simulationof sonic-boompropagation with realistic lpPA13. Comparisonof computercodes for propagationof sonic modelingof the atmosphericturbulence. Allan D. Pierce(Dept. of boomsthrough the atmosphere. JamesP. Chambers,Henry E. Bass, Aerosp.and Mech. Eng., Boston Univ., I l0 CummingtonSt., Boston, MA RichardRasper (Natl. Ctr. for Phys.Acoust., Univ. of Mississippi, 02215) University,MS 38677), RobinO. Cleveland,Mark F. Hamilton,and DavidT Blackstock(Univ. of Texas,Austin, TX 78713-8029) NASA initiatedan exercise to comparesonic-boom propagation codes. The propagationof sonicbooms is from high abovethe groundto Threedifferent codes developed at ourtwo universitiesare compared here: groundlevel, and over the paththe dominant acoustic length scales in the SHOCKN(Mississippi), THOR (Texas),and ZEPHYRUS (Texas; devel- signaturesfall withinwhat is knownas the inertialsubrange, for which opedby L. D. Robinson).Each code includes nonlinear steepening, ab- thereis a considerablebody of basictheoretical knowledge. Any modelof sorptionand dispersion(relaxational and thermoviscous),geometric boom-turbulenceinteraction that requiresa valuefor an outerscale has spreading,and atmospheric stratification. All threecodes calculate steep- veryweak theoretical basis. However, the range of turbulencescales within eningin the time domain.The maindifference is in the calculationof theinertial subrange is hugeand different scales have different effects. The absorptionand dispersion. SHOCKN and ZEPHYRUS use the frequency presentpaper argues that the turbulencecan be splitin a well-definedand domain; the FFT is used to transfer back and forth between the time and logicalmanner, with theresulting scale at whichthe split occurs serving as frequencydomains. ZEPHYRUS employs weak shock theory to reducethe numberof FFT operations.All of THOR'scalculations are done in thetime an outerscale with respectto the turbulencethat affectsthe rise timesof domain.Code accuracy and effectiveness is judgedby comparingground sonicbooms. Although molecular relaxation accounts for a substantial levelpredicted waveforms (input waveforms are specified by NASA). The fractionof the rise times,the bulk of the thickeningduring daytime over- codesare capableof dealingwith arbitraryatmospheric data. Results are flightsis associatedwith turbulence.A theoryfor suchthickening that presentedhere for uniformand isothermal atmospheres, with andwithout simultaneouslytook both nonlinear steepening and turbulence into account the effectsof molecularrelaxation. Early comparisonsrevealed discrepan- hadbeen proposed in theearly 1970sby Plotkinand George, but hadbeen cies,which led to improvementof codes.Current comparisons show ex- criticizedfor itsdependence on thechoice of an outerscale. The proposed cellentagreement. Ground waveforms show surprising sensitivity to input partitioningremoves this objection and combines the salient ideas of Plot- stratificationdata. Somecomparisons of coderunning time have been kin andGeorge with others proposed by theauthor during the same epoch made.The FFT operationsapparently make SHOCKN andZEPHYRUS for the effectsof inertial-subrange-sca]eturbulence on risc times. mn moreslowly than THOR. [Work supported by NASA.]
TUESDAY A[rFERNOON, 30 MAY 1995 AUDITORIUM, 1:30 TO 4:30 P.M.
SessionlpSC
SpeechCommunication: Psychophysics of Speech Perception: What CriticalData are Neededto Improve Low-Bit-RateCoding and AutomaticRecognition
Oded Ghitza, Chair AcousticsResearch Department, AT&T Bell Laboratories, 600 Mountain Avenue, Murray Hill, NewJersey 07974
Invited Papers
1:30
lpSC1.Psychophysics of speech perception: What critical data are neededto improvelow bit-rate-coding and automatic recognition?Oded Ghitza (Acoust. Res. Dept., AT&T Bell Labs., 600 Mountain Ave., Murray Hill, NJ 07974) Thepurpose ofthis special session isto call the attention ofthe hearing science community tothe need for new knowledge onhow speechsegments of durations of 50-150 ms long (e.g., phonemes, diphones), arebeing represented in the auditory system. In this session,the need for such knowledge will beaddressed in the context of twospecific speech-technology applications--low bit-rate codingand automatic recognition (ASR)--which rely on processing speech information ofa segment-lengthduration. Schemes for low bit-ratecoding rely on signal manipulations thatspread over durations of several tens of ms,and schemes for speech recognition rely onphonemic/articulatory information that extends over similar time intervals. Current research efforts are focused on the psycho- physicsof stationaryacoustic inputs, for example, aspects of masking, pitch perception, andsound segregation. Research efforts also existon the cognitive aspects ofspeech perception, forexample, lexical access. In contrast, research onthe psychophysical aspects of speechdynamics, asmanifested in the acoustic properties over durations of tens of ms,still is in itsinfancy.
1:35
lpSC2.Psychophysics ofspeech and speech-like stimuli. Tammo Houtgast (TNO Human Factors Res. Inst., Kampweg 5, 3769 De Soesterberg,The Netherlands} Thestarting point is ti•e representation of speech in thespectro-tcmporal domain. From thi• representation, a number of intcmatlng physicalcharacteristics canbe derived on the dynamic properties of speech. These include the temporal and spectral envelopes, correlationpatterns, and synchrony. The perceptual relevance of thesecharacteristics will be illustrated by reviewinga number of psychophysicaldatafrom experiments including speech-like sounds orspecific laboratory-made dynamic stimuli. Within the context of lowbit-rate coding and automatic recognition, theultimate goal of thiscomparison between speech characteristics andpsycho- physicsis to helpidentify the cues in thespeech signal which are perceptually significant.
3259 J. Acoust.Soc. Am., Vol. 97, No.5, Pt.2, May1995 129thMeeting: Acoustical Society of America 3259
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lp$C3. Speechperception, memory, and cognition:Implications for automaticspeech recognition systems. Patricia•uhl (Dept.of Speechand Hear. Sci., Univ. of Washington,WJ-10, Seatfie, WA 98195) Recentexperiments suggest that people form perceptual representations for speechas a resultof experiencewith a specific language.These representations areargued to takethe form of perceptualmaps stored in memorythat specify distances between speechstimuli. This point will be illustratedwith datafrom cross-language experiments on Americanand Japanese adults using the segmentsh'/and/1/. The results show that the underlying perceptual space encompassing/r/and/l/varies greatly in Americanand Japaneselisteners--their perceptual maps are dramatically different. Cross-cultural developmental studies show that language-specific speechrepresentations are presentearly in life anddiffer in infantsreared in differentlinguistic environments. Further work suggests thatthe perceptual maps resulting from speech experience not only influence auditory speech perception, but influence auditory-visual speechperception in adultsand speech production in infants.Implications for automatic speech recognition systems will be discussed. [Worksupported by NIH.]
2:25
lpSC4. Automaticspeech recognition using signal processing based on auditoryphysiology and perception. RichardStern (Dept.of Elec.and Cornput. Eng., School of Comput.$ei., andBiomed. Eng. Program, Carnegie Mellon tlniv., Pittsburgh, PA 15213-3890) Signalprocessing for automaticspeech recognition has traditionally been inspired more by modelsof speechproduction than by modelsof auditoryperception. While some aspects of humanauditory processing have been implicit in traditionalsignal analysis for speechrecognition, there is growinginterest in thedevelopment of morecomputationally demanding signal processing strategies that are directlymotivated by knowledgeof auditoryphysiology and perception. The useof physiologicallymotivated signal processing hasbeen shown to improvethe accuracy of someautomatic speech recognition systems, particularly in difficultacoustical environ- ments.This talk will review and discussthe role that knowledgeof humanhearing has played in the designof speechrecognition systems.The commonfeatures of auditorymodels that have emerged from variouslaboratories as well as theirdifferences will be discussed.The recognitionaccuracy obtained using auditory models will be comparedwith the accuracyobtained using conventional signalanalysis techniques, as well as theaccuracy obtained using other approaches to robustrecognition that are not physiologically based.Finally, an attemptwill be madeto identifyaspects of monauraland binaural auditory processing that appear to be mosthelpful for robustrecognition. [Work supported by ARPA.]
2:50-3:05 Break
3:05
IPSC5, Achievinghigh qualityspeech at low bit rates:Fundamental issues in psychophysics.Bishnu Atal (SpeechRes. Dept., AT&T Bell Labs.,Rm. 2D-535,Murray Hill, NJ 07974)
Excellentprogress has been made in recentyears in synthesizinghigh quality natural sounding speech at bit ratesas low as 8 kb/s. Rapidlyincreasing demand for speechtransmission over digital radio channels requires that the bit ratesbe decreasedeven further--to 4 kb/sor lower.But, one is not able to achievehigh qualityspeech at theselow bit rates.Why? Low bit rate speechcoders exploit auditorymasking to maskthe quantizing noise in thecoded signal. The current models of auditorymasking are valid only for relatively stationarysegments, such as vowels, in thespeech signal. Much of thedistortions we heardin low bit ratecoders are introduced during transitionalsegments, resulting from lack of psychophysicaldata on perceptionof suchdistortions. A humanlistener is ableto detect suchdistortions in the codedversion without comparing the codedversion with the original.Why is it so?How doesour hearing systemknow that the codedsignal is distorted?Such questions must be answeredbefore progresscan be made in achievinghigh qualityspeech at low bit rates.
3:30
lpSC6. On the perceptualdistance between speech segments. Oded Ghitza and M. MohanSondi (Acoust.Res. Dept., AT&T Bell Labs.,Rm. 2D-536, MurrayHi!l, NJ 07974)
For manytasks in speechsignal processing it is of interestto developan objectivemeasure that correlates well with the perceptual distancebetween speech segments. (Speech segments means pieces of a speechsignal, of duration50-150 ms.)Such a distancemetric wouldbe usefulfor speechcoders at low bit ratesbecause perturbations introduced by suchcoders typically last for severaltens of milliseconds.It woulda!•o be u•ful for automaticap•p•h reeo•nltlon in adverseconditions. glnc• humanb•inga l:•rform well in spite of grossdistortions of thesignal (e.g., due to reverberation,noisy environments, etc.) it isjustifiable to assumethat mimicking human behaviorwill improverecognition performance. In this talk, attemptsat definingsuch a metricwill be described.The problemis approachedin the frameworkof theDiagnostic Rhyme Test [DRT]. The errorsmade by subjectswere measured when judiciously chosentime-frequency "tiles" wereinterchanged between the wordsin eachpair of the DRT test[Ghitza, J. Aeonst.Soc. Am. 94, 2507-2515(1993)]. Next the same task is performed with an array of automaticspeech recognizers [Ghitza and Sondhi, Comp. Speech Lang.7(2), 101-120(1993)], using a parametrizeddistance metric. Finally, the parameters of the distance metric are optimized so as to minimizethe difference between the error patterns of thehuman listeners and those of theautomatic speech recognizers.
3:55-4:30
PANEL DISCUSSION
3260 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3260
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp TUESDAY EVENING, 30 MAY 1995 AUDITORIUM, 7:00 TO 9:00 P.M.
Session leID
Interdisciplinary: Tutorial on Flow-Induced Sound
Kenneth J. Plotkin, Chair WyleLaboratories, 2001 JeffersonDavis Highway,Suite 701, Arlington, Virginia22202
Chair's Introduction--7:00
Invited Paper
7:05
leID1. Flow-inducedsound. Alan Powell (Dept.of Mech. Eng., Univ. of Houston,Houston, TX 77204-4792)
After a brief historicalaccount introducing some lasting concepts, the originsand main featuresof aerodynamicallygenerated soundare describedin termsof the meldingof somepertinent elements of fluid dynamicsand of acoustics.These are, for example, flow separation,flow instability,and vortices on the onehand, coupled with the hydrodynamicflows of acousticmonopoles, dipoles, andquadrupoles on theother. With emphasison thevortex theory of aerodynamicsound, various theoretical approaches are generally describedin physicalterms and are illustratedby a varietyof sound-generatingflows. These may be classifiedas free flowswith no solidsurfaces present (spinning vortices, turbulent jet noise,supersonic jet screech),flows over rigid surfaces (boundary layer noise, whistlingtelephone wires. edge tones, pipe tones,vocal fricatives,and whistling,organ pipes), interaction with steadilymoving surfaces(helicopter blade slap, fan bladeinteraction, but not includingthe rotationalnoise of fansand propellers), flow with excited surfaces(interior aircraft boundary layer noise, aeolian tones, reed and lip-driven musical instruments, vocal chord vibration, snoring and raspberries).Some of theseinvolved no resonanceat all, while othershave flow resonance,acoustic resonance or mechanical vibration or resonance.
WEDNESDAY MORNING, 31 MAY 1995 MEETING ROOM 16, 8:30 A.M. TO 12:00 NOON
Session 2aAA
Architectural Acoustics and Noise: The Americans with Disabilities Act and Acoustical Criteria for the Disabled
David Lubman, Cochair David Lubman and Associates,14301 Middletown Lane, Westminster,California 92683
John Erdreich, Cochair OstergaardAcoustical Associates, 100 ExecutiveDrive, WestOrange, New Jersey07052
Chair's IntroductionS:30
lnvded Papers
8:35
2aAA1.Meeting the challengesof the Americanswith DisabilitiesAct: Providingaccess for peoplewith communication digabiliti•g_ Io Williamg (ProfeggionalPraetieeg Dept.. AmericanSpeech-Language-Hearin• Association. 10801 RockvillePike. Rockville, MD 20852) TheAmerican with Disabilities Act (ADA) is significantnot only as landmark civil rights legislation, but also because it is a turning pointin publicpolicy regarding the importance of communication andcommunication access. In thepast, accessibility policy has focusedon physical/mobilityconcerns and largely ignored needs related to sensory/cognitiveimpairments. More than 34 million Americansof all ages--approximatelyoneof everyten people--have hearing, speech, and/or cognitive language impairments that
3261 J. Acoust.Soc. Am., Vol. 97, No.5, Pt. 2, May1995 129thMeeting: Acoustical Society of America 3261
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp affecttheir ability to work,learn in school,and participate in everydayactivities. ADA regulations address communication access in employment,community programs and businesses, transportation, andtelecommunications. Strategies for communication access and employmentaccommodations varywith the individual/disability andthe type of activity/business.Mostindividuals need strategies that optimizeauditory and visual information exchange, including improvements in environmental conditions (such as reduced ambient noiselevels). New approaches andrethinking are needed regarding (1) assessing communication (dis)ability and needs, (2) the concept of accessibility,and (3} therole of professionals,including interdisciplinary collaborative efforts, in ADA implementation.
9:00
2aAA2.Room acoustics needs of peoplewith hearing impairment. Anna K. Nabelekand Igor V. Nahelek(Univ. of Tennessee, Knoxville, TN 37996-0740) Speechperception of people with hearing impairment is negatively affected to a greaterdegree by background noise and rever- berationthan the speech perception of peoplewith normal hearing. As a consequence,rooms which have adequate acoustics for normal-hearingpeople might be too noisy or tooreverherant for hearing-impaired users. Causes of perceptualdifficulties of hearing- impairedlisteners and data comparing effects of noise and reverberation onspeech perception of normal-hearing andhearing-impaired listenerswill be presented. The number of peoplewith hearing loss grows with age. Two major causes are noise exposure and aging processes.People with hearing loss can obtain improvement in speech communication with hearing aids but poor room acoustics can limithearing benefits and cause hearing aid rejection. Advantages of acoustical modifications, preferential sitting, and use of ampli- ficationin smallrooms will be discussed.Listening systems such as inductionloops, FM, and infraredwill be consideredas alternativesor additionsto acousticalmodifications of largerooms. The listeningsystems can be utilizedby hearingaid users and by peoplewho do not usehearing aids, even those with normalhearing.
2aAA3.The effectsof roomacoustics on normal-hearingchildren: Implications for intervention.Carl C. Crandell (Dept.of Commun.Processes & Disorders, Univ. of Florida,461 Daner Hall, Gainseville, FL 32611)and JosephSmaldino (Univ. of Northern Iowa, CedarFalls, IA 50614) It iswell recognized that the acoustical environment in a classroomis an important variable in thepsyche educational achievement of hearing-impairedchildren. To date,however, there remains a paucityof informationconcerning the importanceof classroom acousticsfor populationsof children with normal-hearing sensitivity. The present discussion will examine:(1) commonlyreported levelsof classroomnoise and reverberation;(2) the potentialeffects of classroomacoustics on the speechrecognition of several populationsof pediatric listeners (young children, children with language/articulation disorders, non-native English children, children withminimal hearing loss, developmentally disordered children, children with central auditory processing disorder); (3) intervention strategies,such as sound field amplification systems, to benefitnormal-hearing children in theclassroom setting; and (4} implications of appropriateclassroom acoustics to theAmerican with Disabilities Act (ADA).
9:50
2aAA4.Proposed guidelines for quietareas in restaurantsfor hearing-impairedindividuals. Ron Moulder (Empire Acoustical Systems,89 ParkAve. W, Mansfield,OH 44902)and DavidLubman (D. Lubmanand Assoc., Westminster, CA 92683) Thepredominant problem of thehearing-impaired individual is speechcommunication. In noisy and reverberant restaurants where speechcommunication is difficult to impossible,these individuals cannot enjoy the experience of diningout. This fact was conveyed to theUS governmentduring hearings for theAmericans with Disabilities Act. A programwas funded by thefederal government to developrecommendations for improvingthe acousticalquality of restaurantsso that hearing-impairedindividuals could enjoy the experienceof diningout. A three-phaseprogram consisting of a literaturesearch, the evaluationof the acousticalenvironment in selectedrestaurants, and the developmentof proposedrecommendations to improvespeech communication by hearing-impaired individualsin restaurantswas carried out by Battelle.An advisorypanel of professionaland lay individualswas established to review the work of this program.The proposedrecommendations developed focused on reducingreverberation times and noiselevels in restaurants.Several recommendations are presentedfor achievingthese goals.
10:15-10:25 Break
ContributedPapers
10:25 the aged. For a group of 30 residenl•s,scope of participation m acnvlttes and qualityof communicationduring activities were measuredfour times 2aAAS. Evaluation of accessibilityneeds in a home for the aged. M. KathleenPiehera-Fuller (Schoolof Audiel. and SpeechSci., Univ. of overtwo years,twice before and twice after program implementation. In a British Columbia, 5804 Fairview Ave., Vancouver,BC V6T IZ3, Canada) pilot study,groups of residentsand staff identifiedsituations at the home where they felt that hearingwas important.The evaluationof communi- Audiologicalrehabilitation has traditionallyfocused on the hard-of- cation functionwas keyed to thesesituations. The patternsof scopeand hearingindividual. In contrast,the needsof groupswho performspecific qualityof communicationwere usedto formulatean accessibilityplane. activitiesin specificlocations must be evaluatedin planningfacility-based Baselineand outcomedata regardingthe extentto which the program accessibilityprograms. Such evaluations are necessarywhen planners de- signprograms where solutions may he achievedby a combinationof strat- accomplishedaccessibility will be presented.For example,the program egiesincluding modification of the environment,provision of personalor rendered meetings and chapel services accessible to most residents institutionalassistfive technology, or communicationtraining. The present whereassituations such as diningin the dining hall remainedinaccessible. study demonstrateshow accessibilityneeds were evaluatedin a home for [Worksupported by NHRDP.]
3262 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3262
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 10:40 increasesthe capability for auditorycommunication by: (1) loweringin- terferingr'everberant noise levels generated bypeople and trains, and (2) 2aAA6, Developmentof acousticalcriteria in a schoolfor children increasingthe clarity of speechfrom people and audio systems providing with healing disabilities. John Erdreich and R. Kring Herbert railway information. (OstergaardAcoust. Assoc., 100 ExecutiveDr., W. Orange,NJ 07052)
Classroomsfor the teachingand rehabilitationof hearing-impaired childrenpose special problems in acousticaldesign. Both Elliot [L. L. Elliot,'J. Acoust.Soc. Am. 66, 12-21; 651-653 (1979)] and Mills [J. Acoust.Soc. Am. 58, 767-779 (1975)] haveshown that the levelsof noise 11:10 whichinterfere with speechperception in childrenwithout hearing impair- 2aAA8. Influence of impulse noise on speech transmission index. mentare lower thanthose which interfere with intelligibilityin adults.It is Miomir MijiE (Facultyof Elec. Eng.,P.O. Box 816, l1000 Belgrade, logicalto conclude,therefore, that the designof roomsin schoolsfor the Yugoslavia)and MiodragPopovi6 (INTELSAT, Washington, DC 20008) hearinigimpaired should include criteria more stringent than those for other classrooms.This approach was adopted in establishingc{iteria for the This paperanalyzes the influenceof impulsenoise impairments in a SummitSpeech School which conducts two distinctprograms of speech telecommunicationchannel on the speechtransmission index (STI) value, trainingfor hearingimpaired children: One for childrenfrom birthto age which was measuredusing RASTI method.So far STI has not been ap- threeand the other, for ages 2« to5. Several factors were identified for plied in telecommunicationsas a speechtransmission quality measure. particularattention including control of activity noise without excessive Impulsenoise components were formed as IEEE standardimpulse streams. soundabsorption and controlof flutterecho. Among the criteria recom- Impulsenoise amplitude level relative to thelevel of reference(RASTI) mended were minimum sound isolation between classrooms and other signal as well as the durationbetween successive impulse events were spacesof STC-48 andmaximum background sound levels of RC-25. Cri- variedin a channel.Consequently, STI valuewas determined as a function teria for otherspaces and their basiswill be presented. of thesetwo parameters.In the samechannel PB-Word Scoreevaluation was alsoperformed. As a result,the correlationbetween PB-Word Score 10:55 andSTI valuefor a telephonechannel with impulse noise impairments presentwas establishedin this paper. 2aAA7. Acoustical design of the New York railway stations with improved accessibilityfor hearing and visually impaired persons. Robert Nichols (Nichols Design Assoc., Inc., P.O. Box 11251, Washington,DC 20008) and GeraldHenning (Miller HenningAssoc., 11:25-11:30 Break Inc., McLean, VA 22101)
An acousticaldesign of the New York railway stationsis proposedto improvethe acousticalaccessibility for personswith hearingand visual impairments.The acousticaldesign includes methods and materialsfor reducingreverberation times in the stations.Reducing reverberation times 11:30-12:00 PANEL DISCUSSION
WEDNESDAY MORNING, 31 MAY 1995 GRAND BALLROOM CENT,RAL,8:00 A.M. TO 12:45P.M.
Session 2aAO
AcousticalOceanography: Ocean AcousticTomography: Observing the Ocean in the 1990s III
Yves Desaubies, Chair Laboratoirede Physiquedes Oceans,IFREMER, BP 70, 29280 Plouzane,France
Chair's Introduction---8:00
ContributedPapers
8:05 internaltide will be given. Beamformingthe internaltide M 2 and K 1 harmonicconstants determined on eachof the 15acoustic paths suggests 2aAO1. The internal tide of the western North Atlantic observed two originsof significantinternal tide generation are the Blake Escarpment using long-range reciprocal acoustic transmissions. Brian D. andthe continental sheif north of PuertoRico. The nontidal,high- Dushaw (A.P.L., Univ. of Washington,1013 NE 40th St., Seattle,WA frequencyvariability (>• cpd)is dueto internal-wavesound-speed and 98105-6698), Peter E Worcester,Brace D. Comuelle (Univ. of currentvariability. : California,La Jolla,CA 92093-0213),and BruceM. Howe (Univ. of Washington,Seattle, WA 98105-6698) 8:20
Time series of ray travel times were obtained at 350-, 410-, and 2aAO2. Tomographicinversion of fish parameters in shallow water. 670-km rangesin the westernNorth Atlanticduring the 199l-2 Acoustic OrestDiachok. (SACL,ANT Undersea Res. Ctr., La Spezia,Italy) Mid-OceanDynamics Experiment (AMODE). Transmissionswere re- cordedfor approximately300 daysbetween six transceivers in'a pentago- Simulationsof WestoWsmeasurements of the temporal variability of nal array.Sound-speed variability is separatedfrom currentvariability by anomalouslylarge atteauationdue to fish, suggestthe possibilityof to- calculatingthe sum of reciprocaltravel times. Both phase-lockedand mographicinversion q.f. pelagic fish parameters over large spatial dimen- narrow-bandinternal-tide sound-speed variability, caused by the internal- sions(nominally 50 km radius)in shallowwater. These measurements tide isotachdisplacement, are observedby the sumtravel times. The de- re•'•alresonances which are a functionof fishbladder size and depth. scriptionof theacoustic array as a high-directivityantenna for theincid?nt Computationssugges([hat the latter may be inferred from modal attenua-
3263 d. Acoust.Sec. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3263
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp tionmeasurements [Diachok, European Conference on UnderwaterAcous- signalsduring their propagationin the Fram Straitcross section with vari- tics(1994)], hypothetically permitting unambiguous estimation of bladder ableupper layer mean temperature were considered on the baseof the ray size.In thehorizontal dimension pelagic fish concentrate into "clusters"of theoryapproximation. The resultsof computersimulation of the process schoolsat scales,which are driven by the "patchiness"of plankton,which are presented. in turnis hypotheticallycontrolled by atmosphericand bottom conditions,
and by oceanicmesoscale phenomena such as eddies,fronts, and up- 9:20 wellingevents. A fixed,large-scale tomegraphic array consisting of several widelyspaced transmitters and receivers, designed to invertocean param- 2aAO6,A full field approachto acoustictomography of oceanic etersat low frequenciesand fish parameters over a broadrange of higher currents. Oleg A. Godin (NOAA/AtlanticOceanogr. and Meteorel. frequencies,together with quasisynoptic measurements of plankton param- Lab., 4301 RickenbackerCswy., Miami, FL 3.3149)and Dmitry Yu. eters(probably from ships),would permit investigation of fishadapta- Mikhin (P. P. ShitsheyOceanogr. Inst. of the RussianAcad. Sci., Moscow tion(s)to the temporallyevolving mesoscale environment. Criteria for the 117851,Russia) designof sucha bioacousticobservatory, and its advantages and disadvan- tagescompared to shipbornemethods and fixed long-range active moni- Traditionallyit is nonreciprocityin traveltimes along identified pairs toring, will be discussed. of spatiallyclose eigenrays that serves as input data for a current'svelocity inversion.In shallowwater manyof the raysare bottom-interactingand cannotbe resolvedor identified.Hence the traditionalapproach results in a verypoor or nonexistentresolution in thevertical plane [D. S. Ko et al., 8:35 J. Geephys.Res. 94, 6197-6211 (1989)].To avoidthese problems it is suggestedthat one matchnonreciprocity of acousticcontinuous waves 2aAO3. Scatteringof acoustictomegraphic signals in shallow water measuredat a setof points,e.g., at a verticalarray..&nalytic studies indi- by internal waves. JamesF. Lynch (WoodsHole Oceanogr.Inst., catethat nonreciprocity of thephase of a cw signalis sensitiveto the flow WoodsHole, MA 02543), Guoliang'Jin (AcademiaSinlea, People's velocitybut doesnot depend,to firstorder, on fluctuationsin soundspeed Republicof China), PeterTraykovski (MIT/WHOI Joint Programin or on uncertainties in transceiver location and, therefore, can he used as Oceanographyand Oceanographic Engineering, Woods Hole, MA 02543), inputdata for currents inversion. Respective matehed-phase nonreciprocity Ching-sangChin, and JamesH. Miller .(NavalPostgraduate School, tomography(MPNT) is simulatednumerically, including effects of acous- Monterey,CA 93943) tic SNR, systematicand randomenvironmental ntismatches, number of This talk examines how internal waves in shallow water cause travel transceiversin the array,uncertainty in theirpositions, etc. andcompared time fluctuationsin acoustictomegraphic Wansmissions. Ray and mode to otherpossible inversion schemes. It is concludedthat MPNT couldbe a theoryexpressions are developed and calculations are compared to travel practicaltool for monitoringocean dynamics in shallowwater. [Work time fluctuationdata takenfrom the 1992 BarentsSea Polar Frontexperi- supportedby NR(3and RBRF.] ment.While thereis basic agreement, there is stillmuch room for improve- mentof thebasic theory and experiments. Directions of furtherresearch in 9:35 boththeory and experiment are discussed. [Work supported by ONR.] 2aAO7. 1994 moving ship tomography experiment in the western Mediterranean. Dmitry Yu. Mikhin, Dmitry L. Aleynik, Sergey V. 8:50 Burenkov, Yury A. Chepurin, Viktor G. Selivanov, Sergey Ya. Molehaney (P. P. ShirshovOceanogr. Inst. of the RussianAcad. Sci., 2aAO4. Internal-fide inversions Uom a 1000-km Pacific acoustic Moscow117851, Russia), and Oleg A. Godina) (NOAA/Atlantic propagationexperiment in the Pacific. CharlesBracher and Stanley Oceanographicand MeteorologicalLab., Miami, FL 33149) M. Flatte (Phys.Dept., Univ. of California,Santa Cruz, CA 95064) A tomegraphicnetwork of sevenmoored transceivers was deployed in The Slice89experiment sent sound pulses through the Pacificover a the westernMediterranean basin in early 1994 by IfM (Kiel, Germany), 1000-kmpath. Different identified wavefronts showed clear M2 internal- IFREMER (Brest,France), and WHOI (WoodsHole, USA) in the frame- tidalsignals in theirarrival-time series. We have examined internal-tide work of the THETIS-2 project.Signals emitted by the transceiverswere modelscomposed of thefirst three vertical modes in orderto fit theSlice89 alsoutilized in the 8-weekmoving ship tomography experiment, MOST. data. The horizontal directions of the three modes were allowed' to be Acousticmeasurements were made with a singlehydrophone and an eight- different.The horizontalstructure of the modelsvaried from planewaves elementvertical array deployed from a driftingvessel and were comple- to wavesthat are localizedalong the directionof acousticpropagation. It mentedby CTD casts.The setof observationpoints was chosen to provide has been found that the best-fitinternal-tide model within the parametri- detuiledCTD and acousticdata along existingpropagation paths of the zation,and the resulting fit is reasonable.These results along with thoseof THETIS-2 networkfor comparisonof traditionaland moving ship tomog- other experimentsin the samegeographical area have beencompared. raphyunder well-controlled environmental conditions as well as to create numerousadditional propagation paths to improveresolution in the hori- zontalplane. By precisecompensating theDoppler shift due to vesseldrift• the data processingtechnique used made it possibleto resolveeigertray 9:05 arrivalsup to 400-600 km rangefor differentsources. Preliminary results 2aAO5. Numerical simulation of the sensitivity for the temperature of theMOST dataprocessing, analysis, and interpretation will be presented remote acoustics control in Fram Strait environmental conditions. atthe meeting. [Work supported byISF and INTAS.] a)On leave from P. P. KonstantinA. Naugolnykh (Environmental Tech. Lab., NOAA, Boulder, ShitsheyOceanography Institute, Moscow. CO 80303), Ola M. Johannessen(Nansen Environmental and Remote
Sensing Ctr., Bergen N5037, Norway), Igor B. Esipov, Oleg B. 9:50 Ovchinaikov,Yury I. Tujilkin, and Viktor V. Zosimov (N. Andreyev Acoust. Inst., Moscow 117036, Russia) 2aAOS. Acoustic footprints of an interthermocline eddy: Field experiment and numerical simulations. Dmitry Yu. Mikhin, Dmitry An importantrole of the generalproblem of globalclimate changes is L. Alcynik, SergeyV. Burenkov,Yury A. Chepurin,Vik•or G. Selivanov, the heat inflow from the Atlantic Ocean to the Arctic basin control. The SergeyYa. Molchanov (P. P. ShirshovOceanogr. Inst. of the Russian effectivetool to performit is the acousticmethods application. Some Acad.Sci., Moscow 117851, Russia), and OlegA. Godina• (NOAA/ aspectsof this problemconnected with the averagewater temperature AtlanticOceanogr. and Meteorol.Lab., Miami, FL 33149) measurements in some cross section of the Fram Strait are considered. It is supposedthat the temperature change takes place in theupper 200-m layer A movingship tomography experiment (MOST) wascarried out in the of the ocean which is typical for the winter Fram Strait environmental westernMediterranean basin in 1994.Six mooredtransceivers deployed in conditions.Variations of the amplitudeand the arrival time of the acoustic the area by IfM (Kiel, Germany),IFREMER (Brest,France), and WHOI
3264 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3264
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp (WoodsHole, USA), in the frameworkof theTHETIS-2 project, were 10:50 utilized as wide-baud sound sources for the MOST. An interthermocline eddywith cold core was found during the MOST. Detailed CTD surveys 2aAOll. Decadal variability in acousticthermometers interpreted wereperformed along several sections of theeddy. In thehorizontal, it was with oceanmodels. JohnSpiesberger, Mark Keller (Dept.of Meteoro/. closeto an ellipsewith axesof 25 and40 nm.The sound-speeddifference andthe Appl. Res.Lab., 512 WalkerBldg., Penn State Univ., University at givendepth inside and outside the eddy was up to 2 mJs.Within the eddy Park, PA 16802), Mark Johnson (Univ. Alaska--Fairbanks,Fairbanks, core the sound-speedgradient was an order of magnitudeless than in AK 99775-1080), Harley Hurlhurt (Naval Res. Lab., StennisSpace surroundingwaters. Acoustic signals from the transceiverswere recorded Center,Bay St. Louis,MS 39522), and JamesO'Brien (FloridaState at 16 pointswithin and aroundthe eddyin orderto studyfeasibility of Univ., Tallahassee,FL 32306) reconstructionof mesoscaleinhomogeneities of this type by acousticto- Travel timesof acousticsignals were measuredbetween the bottom- mographymeans. A techniqueof coherentsignal processing used made it mounted Kaneohe source near Oahu and seven SOSUS stations at 3000- possibleto resolvemultiple eigenray arrivals from four transceivers at each 4000-kmdistance during 1983-1989. The NavalResearch Laboratory hy- pointof observations.Results of mathematicalmodeling of the acoustic drodynamiceddy resolvingmodel yields changes in traveltime whose effectsof theeddy and their comparison with the experimental data will be standarddeviations are consistentwith the data.The modelpredicts that reported.[Work supported by ISF andINTAS.] a)Onleave from P. P. between1981-1993, Rossbywaves modify travel times by one second. ShirshovOceanography Institute, Moscow. Mesoscaleeddies modify travel times little comparedto Rossbywaves. The largest Rossby waves are descendantsof El Nino. Travel times 10:05-10:20 Break changesare sensitiveindicators of predictablefeatures in the Naval Re- searchLaboratory model. [Work supported by theStrategic Environmental Researchand DevelopmentProgram, managed by the AdvancedResearch 10:20 ProjectsAgency.] 2aAO9. On acoustictomography of internal waves. JohnA. Colosi (ScrippsInst. of Oceanogr.,IGPP-0225, UCSD, La Jolla,CA 92093}and StanleyM. Flatte (Univ. of California,Santa Cruz, CA 95064) 11:05
With the plannedacoustic instrumentation of severalof the worlds 2aAO12. Surface suspendedacoustic receiver for acoustic oceanbasins, the possibility exists for measuringthe strength of the inter- tomography.John S. Spiesberger,Carter Ackerman, and Bruce Einfalt nalwave field as a functionof depth,time, and geographical position. The (Dept.of Meteorol.and the Appl. Res. Lab., 512 Walker Bldg., Penn State variabilityof internal-waveenergies and spectra over these parameters will Univ., UniversityPark, PA 16802) provideinformation on the sources and sinks of internalwaves. In theearly eightiesFlatte formulated an analytic,ray-based framework for internal- A surfacesuspended acoustic receiver (SSAR) is showncapable of wave tomography.Analysis of the SLICE89 experimentcombined with processingand transmitting acoustic tomography data through ARGOS to supercomputernumerical simulations have recentlyshown that internal laboratoriesin near-realtime. Ray theoryis shownadequate for validating waveshave even stronger effects on signalstransmitted over 1000km than thedata from the SSAR. [Work supported by theStrategic Environmental were expectedfrom the early ray-basedtheory plus the Garrett-Munk Researchand Development Program, managed by theAdvanced Research (GM) spectrum.It wasfound that the ray-basedtheory is adequatefor ProjectsAgency.] identifiablewavefronts that turn at depthsbelow 100 m; energythat reachesvery shallowdepths and energy that stays near the sound-channel
axis do not behaveso simply.The numericalsimulations establish an 11:20 internal-wavestrength below 100 m of 0.5_•0.25 the referenceGM level, and pointto knownlimitations of the GM spectrumin the upperocean. 2aAO13. ATOC-FACT arrival-time differences. David Palmer Simulationsto 3000 km havequantified the rangedependence of internal- (NOAA/Atlantic Oceanopt. and Meteorol. Lab., 4301 Rickenbacker waveeffects, and extensions of ray-basedtheory attempt to explainthese Cswy., Miami, FL 33173), Leon Krige (Inst. for Maritime Technol., effects. Simon'sTown, 7995 SouthAfrica), Geoff Brundrit (Univ. of Cape Town, Rondebosch,7700 SouthAfrica), and Kurt Metzger (Univ. of 10:35 Michigan,Ann Arbor,MI 48109-2122)
2aAO10. Internal wave effects on shallow water acoustic The acousticthermometry of oceanclimate-feasibility ascension Cape tomography.Xin Tangand F. D. Tappert (Appl.Marine Phys., Univ. Town(ATOC-FACT) propagation experiment took place during November Miami, RSMAS, 4600 RickenbackerCswy., Miami, FL 33149) andDecember of 1992.Explosive charges were detonated near the oceanic sound-channelaxis at five locationsin the SouthAtlantic off CapeTown. Full-wavenumerical simulations of internalwave scatteringof sound The resultingsignals were recorded on bottom-mountedhydrophones at in shallowwater are performedwith an efficientbroadband PE modelthat Ascension,Navy horizontalarrays off Bermuda,bottom-mounted hydro- alsoincludes scattering by bathymetricvariations. Bathymetric scattering phonesoff Kaneoheand Wake and from a hydrophonearray deployed by itselfgives an exponentiallylarge number of unresolvablemultipaths as from a researchship off SouthernTasmania. The primary goal of the predictedby ray chaostheory. When internalwaves that evolve dynami- experimentwas to determinethe extent that the acousticpath between cally in geophysicaltime are included,the unresolvablemultipaths are Ascensionand Cape Town is blockedby Bonaparte'sSeamount and other found to be temporallyunstable with coherencetimes less than a few bathymetricfeatures. Secondary goals were to determinethe horizontal minutesat rangesgreater than a few tensof water depthsin shallowwater, arrival structureat Bermudaand the temporalarrival structureat Ascen- exceptpossibly for rare pathsthat are shieldedfrom internalwaves such as sion, Hawaii, and off Tasmania.After giving an overviewof the experi- within strongsurface ducts. Since traditionaltravel-time ocean acoustic ment, we use recordeddata to discussthe question of how precisely tomographyrequires many stable,resolvable and identifiablepaths, con- arrival-timedifferences of explosivesignals can be measured.Detonations ditionsthat are not satisfiedin shallowwater at longerranges, some other separatedboth temporallyand spatiallyare considered.It is hopedthis inversionmethod will haveto be developedfor remotesensing of shallow work will contributeto an understandingof the role explosivesignals can waterenvironments. [Work supported by ONR.] play in the designof a global ATOC network.
3265 J, Acoust,Soc, Am,, Vol. 97, No, 5, Pt12, May 1995 129th Meeting:Acoustical Society of America 3265
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp Invited Paper
11:35
2aAO14.Observing the ocean in the1990s: Where do we stand now? CarlWunsch (Dept. of Earth,Atmospheric andPlanetary Sciences,Room 54-1524, MIT, Cambridge,MA 02139) Thirteenyears ago, a paperwith almost the same name as this present session was published byMunk and Wunsch. Wa•s in which oceanographerswere likely to be observingthe ocean 10 years later was speculatedupon. The specialfocus was climate-scale problemswith acoustictomography and satellitealtimetry as the naturalcomplementary observational technologies. At the time, the tomographicidea was only about4 yearsold, andnow that it is half-waythrough the 1990s,it is interestingand perhaps useful to look backto understandthe extent to whichthe vision of the role of tomographyin oceanographyhas come to pass.A numberof problems will be considered,from the technicalto the sociologicaland attemptto make yet anotherforecast of where tomographyin ocean- ographymight be in another10 years.
12:00-12:45
PANELDISCUSSION
WEDNESDAY MORNING, 31 MAY 1995 MEETINGROOM 3, 8:00TO 11:45A.M.
Session 2aEA
EngineeringAcoustics and Noise: Active Control of Noiseand Vibration I
Sung H. Ko, Cochair : NavalUndersea Warfare Center, New London Detachment, New London, Connecticut 06320 Elizabeth•. McLaughlin,Cochair Naval UnderseaWarfare Center, New LondonDetachment, New London,Connecticut 06320
Chair's Introduction4:00
Invited Papers
8:05 2aEA1.Active control ofnoise and vibration: Overview andcurrent applications. ChrisR. Fuller (Vib. andAcoust. Lab.,Dept. of Mech. Eng., VirginiaPolytech. Inst. and StateUniv., Blacksburg,VA 24061) In thisintroductory presentation the.principles and components of active control systems will be brieflyoverviewed. Current researchtopics and areas of applicationwill be discussedincluding duct noise, machinery isolation, wave control in beams,interior noisein aircraft,and structurally radiated sound. The use of adaptivematerials in activenoise and vibration control will alsobe touched upon.The presentation will finishwith a discussionon thepresent limitations of activecontrol and future promising directions.
8:35 2aEA2.Active controll New paradigms forstructural acoustics anddynamics. Albert J.Tucker (Office ofNaval Res., 800 N. Quincy St., Arlington,VA 22311-5660) Originallythe concept of activecontrol conveyed the simple notion of creating"antinoise" or "antivibration;;'these ideas implied thatsimple antiphase motions could be propagated tocancel unwanted noise. However, recent advances insignal processing, coupled withgigatop digital signal processor s,augur new ways to understand andcontrol complex dynamic systems. Among these are shifting wavenumbers from radiating to nonradiatingcomponents and modifying structural impedances to create large dynamic masses, stiffnesses,and/or damping. Hence one electronically modifies the dynamicsof complexsystems to achieveacoustic radiation reduction,orto have a physicallylightweight structure emulate the dynamics of a heavier,stiffer structure. This fundamental scientific understandingoffers new opportunities for developmentof newtechnology for controlalgorithms, sensors, and actuators. As a result, activecontrol is emergingas viableaddition to the engineeringtoolkit for noiseand vibrationreduction.
3266 d. Acoust.Soc. Am., Vol. 97, No.5, Pt. 2, May1995 129thMeeting: Acoustical Society of America 3266
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2sEA3.Silencers: The impactof activecontrol. L. 1. Eriksson(DIGISONIX, Inc., 8401 Murphy Dr., Middleton, WI 53562)
Over the pastdecade, powerful new adaptivetechniques have been developed for the activecontrol of soundand vibration. One of theareas that has received the most attention is theapplication of activecontrol to enhancethe performance of silencersused on ductsor pipes.Active silencing is oftencombined with passive silencing to createa newform of hybridsilencer. These silencers can be usedas intakeor dischargesilencers for heating,ventilating, and air conditioning(HVAC) fans, industrial fans, rotary blowers, compressors,internal combustion engines, gas turbines, pumps, and related equipment. This paper will reviewthe use of activecontrol for theseapplications with particularemphasis on thedifferent reasons generating the interest in activecontrol for eachapplication. Amongthe potential advantages of activecontrol for silencersare improvedlow frequencyperformance, reduced flow restriction,and decreasedsize and cost. The degree to whichthese potential advantages can be realized in specificapplications can vary considerably aswell as the ultimate impact of theimprovement for theend user. These issues will be discussedusing a numberof actualexamples andimplications for the futureuse of activecontrol will be suggested.
9:25
2aEA4.Active control of aircraft cabinnoise. GopalP. Mathur (McDonnellDouglas Aerospace, 1510 Hughes Way, Mail Code 71-35, Long Beach,CA 90810-1870)
Aircraftcabin noise control in thepast has relief heavily on improvingsidewall attenuation by passive"add-on" treatments. The conventionalpassive methods, such as adding mass, damping, or acoustic absorption, etc., not only impose a stiff weight penalty, they arealso ineffective in improvingthe low-frequency sound transmission loss of an aircraftfuselage sidewall. Active control of sound insideaircraft cabins has been the focus of researchin recentyears and has shown considerable promise. Laboratory and in-flight tests of prototypeactive control systems for tonal noise reduction using secondary speakers have demonstrated thefeasibility of activenoise control(ANC) in aircraftcabins. In recentyears active structural acoustic control (ASAC) has also been applied to aircraftfuselage structuresin controlling low- to mid-frequencystructural sound radiation. In theASAC technique, control forces are applied directly to thevibrating structure by actuators(such as piezoelectric transducers) instead of usingloudspeakers to minimize the radiated sound field.The ASAC approach is alsoimportant in thedesign of "smartstructures," which incorporate both sensors and actuators in the structurefor noise and vibration control. This paper presents results of investigations(conducted atMcDonnell Douglas) of application of bothANC andASAC techniques to a full scaleaircraft fuselage. Significant sound pressure reductions were achieved throughout thecabin for multiple tonal frequencies ofexcitation. The performance of theASAC method is compared with that of theANC system usingspeakers. The flighttest results with a prototypeANC systemin an MD-80 aircraftwill alsobe presented.
9:50
2aEA5.Feedback-stabilized artificial bedrock: A practicalimplementation of a passive/activevibration isolation system. A. M. Beard,D. W. Schubert(Barry Controls, 40 GuestSt., Brighton, MA 02135),and A.H. yonFlotow (HoodTechnol. Corp., Hood River, OR 97031)
Activecontrol in thepresence of resonantstructural dynamics is challengingsince such dynamics are both uncertain and easy to destabilize.This is particularlytrue when broadband control is required.Active vibration isolation is plaguedby suchdifficulties. In spiteof muchdevelopment work, few systemsare in serviceand these remain very sensitiveto structuralresonances. For eachsuch system,the control logic is fine-tunedduring installation. When the system's environment changes (sometimes only slightly), unstable behavioris common.This presentationdescribes basic options in passive/activevibration isolation and highlights mechanical archi- tectureswhich make robustactive control possible. Simple theoretical arguments are supportedwith experimentalevidence. The presentationconcludes with a detaileddescription of a recentlydeveloped system which is basedupon one such mechanical archi- tecture;Barry Controls' STAC1S-2000. This systemuses seismic motion sensors (geophones) and piezo-ceramic stack actuators to createfeedback-stabilized "artificial bedrock." Vibration-sensitive payloads are mountedto thesestiff, quiet points.The system deliversthe isolation performance of a well-damped0.3-Hz passive mount and the stiffness (to inertialspace) of a 25-Hz mount.The systemis robust to the dynamicsof both the vibration sourceand the receiver.
10:15-10:30 Break
ContributedPapers
10:30 formulatinga passive/activenoise suppression device that can efficiently operateover a broadrange of frequencies.In this research,the experimen- 2aEA6. Smart foam design and applicationsin active structural tal deviceis comprisedof a layerof piezoelectricmaterial embedded in a acousticcontrol. CassandraA. Gentry, Cathy Guigou, and Chris R. Fuller (Vib. andAcoust. Lab., Dept. of Mech. Eng.,Virginia Polytech. partiallyreticulated polyeurethane foam. Dependingon the specificappli- Inst. andState Univ., Blacksburg,VA 24061-0238) cation,the distributedactuator alters the surfaceimpedance of the passive absorbersuch that an incident acousticwave is totally reflectedor ab- Acoustic foams possessinherent high-frequency sound absorbing ca- sorbed.l•rror sensorconfigurations include mierophonesor piezoelectric pabilitiesfor radiationand reflectioncontrol of structures.Comparatively, sensorsintegrated directly into the noise suppressiondevice creatinga active noise control systemsgenerally do not perform well at high fre- compactpassive/active system. Experimental results are presentedfor pis- quenciesdue to the increasingcomplexity of the physicalmodel and the ton radiationcontrol. An analyticalmodel of smartfoam is describedand necessaryhigh speeddigital signal processing. The "smartfoam" concept simulationsare presentedto illustratethe potentialof the device and the anddesign originates from the combinationof thesetwo controlstrategies interactionbetween the passiveand active components.
3267 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3267
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2aEA7. Adaptive control of sound reflection. SamsonBeyene and 2aEA9. Implementation of fast transversal filters for active RicardoBurdisso (Vib. andAcoust. Lab., Dept. of Mech. Eng., Virginia structural acousticcontrol. Marcus J. Bronzel and ChristopherR. Tech.,203 RandolphHall, Blacksburg,VA 24060) Fuller (Vib. and Acoust. Lab., Virginia Tech., Blacksburg,VA 24061-0238) The presenceof an air cavity behind a layer of absorptivematerial createsan impedance-releaseboundary condition at the interfacebetween The designof an optimalfeedforward controller in activenoise control the material and the air cavity. This boundarycondition resultsin high applicationsfor controllingthe soundradiation from a vibratingstructure absorptioncoefficients over relativelynarrow frequency bands. These high can be seenas a systemidentification problem. Most controlimplementa- absorptionvalues depend on the depthof the air cavity which in turn is a tions usea stochasticgradient search algorithm to adaptivelyidentify the functionof frequency.Therefore, the impedance-releaseboundary condi- impulseresponse of the optimalcontrol filter. The convergenceproperties tion occursonly at a few discretefrequencies. The activecontrol system of the widely usedfiltered-x LMS algorithmdepend on the signalproper- usesan adaptivefeed-forward filtered-x LMS controlalgorithm to main- tiesof thefiltered reference signals. Sensing the reference signals from the tain the impedance-releaseboundary condition over a broad frequency vibratingstructure is inevitablein mostreal applicationsand will effec- range.This is doneby separatingthe incidentand reflected vector intensity tivelyresult in structuralfilmring of theunknown noise source. The filtered within the air cavity usingtwo microphonesand a wave deconvolution referencesignals from a structuralsensor generally exhibit a largeeigen- circuit.A speakerinside the cavityis usedas an actuatorto minimizethe valuespread resulting in poorconvergence properties of the adaptivecon- reflectedintensity vector. The resultis optimumabsorption over a broad troller. A new extended-filtered-xapproach has been developedwhich frequencyrange, including low frequencies.Very goodagreement is found makesthe implementationof fast RLS type algorithmspossible. These betweennumerical simulation and experimentalresults. The experimental algorithmsare basedon an orthogonalprojection of the predictorerror into resultsshow high absorptioncoefficient (0.8-1.0) over a wide frequency the subspaceof the filteredreference signals and thereforeconverge inde- band (100-2000 Hz). pendentfrom the underlyingsignal statistics.Experiments for active con- trol of noisefrom a vibratingplate have been conductedwhich demon- 11:00 stratethe superiorcontrol performanceof fast transversalfilters.
2aEA8. Optimum design for feedforward active structural acoustic
control of complexstructures. H6ctor M. Rodriguez,Ricardo A. 11:30 Burdisso,and Chris R. Fuller (Vib. and Acoust.Lab., Dept. of Mech. Eng., Virginia Polytech. Inst. and State Univ., Blacksburg, VA 2aEA10. Normalizedstochastic gradient method for nonstationary 24061-0238) environment. K. Lee and Jung G. Shin (Dept. of Elec. Eng. and Cornput. Sci., Stevens Inst. of Technol., Castle Point on the Hudson, An efficient design formulation for feedforward active structural Hoboken,NJ 07030) acousticcontrol systems for complexstructures and disturbancesis pre- sented.The approachconsists in a multileveloptimization procedure. The The normalizedleast-mean-squares (NLMS) methodhas been adopted upper level part is carriedout in the modal domain where the optimum for a widerange of adaptivefilter applicationsdue to its simplestructure modalcontrol forces and modalerror sensorcomponents which minimize and low complexityof computation.However, under certain circum• the total radiatedpower are obtained.These optimummodel parameters stances,the convergencerate may not be satisfactory.The performance are then usedin the lower level optimizationto obtainthe physicalchar- mayeven be poorerunder certain nonstationary situations. A new normal- acteristicsof the transducersto be implemented.This separationbetween izedstochastic gradient (NSG) method is suggestedto overcomethe draw- the modal domainand the physicaldomain during the designprocess backsof the NLMS method.The mainfeatures of theNSG methodare (1) allowsthe designerto investigatedifferent control system configurations in thetime varyingconvergence parameter and (2) theonset detection. While the upperlevel part with minimumcomputational effort. The formulation in theNLMS methodthe convergence parameter is fixed,it is a functionof is capableto handlethe design of multiple-inputs,multiple-outputs control time in the NSG method. It is selected to minimize the conditional variance systemsand multiple frequencyexcitations. The proposedapproach is of the filter coefficientsat the next stepgiven a setof the previouscoef- demonstratedfor the caseof a simplysupported plate excited by a periodic ficients.The time-varyingsequence of the convergenceparameter makes point force. The first eight modesare includedin the analysis.Several theNSG methodconverge fast. The new NSG methodhas the capability of differentcontrol system configurations are investigated.The resultsshow the onsetdetection. It detectsthe statisticalchanges of the desiredinput that the optimum configurationsyield reductionsin the total radiated and by resettingthe adaptiveprocedure it keepstracking the changed power of up to 26 DB, dependingin the numberof control channelsand signal.The simulationsshow that the new NSG methodoutperforms the the amountof allowedcontrol effort. [Work supportedby the Officeof NLMS methodunder both stationaryand nonstationaryenvironments. Naval Research.] [Worksupported by DeewooMotor Company, Seoul, Korea.]
3268 J. Acoust.Soc. Am., Vol. 97, No.5, Pt.2, May1995 129thMeeting: Acoustical Society of America 3268
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp WEDNESDAY MORNING, 31 MAY 1995 MEETING ROOM 2, 8:25 TO 11:50 A.M.
Session 2aMU
Musical Acoustics:The Bowed String
RogerJ. Hanson,Chair PhysicsDepartment, University of NorthernIowa, Cedar Falls. Iowa 50614
Chair's Introduction--8:25
Invited Papers
8:30
2aMU1. Musicaloscillator simulations: From curioMty-drivenscience to commercialproduct. RobertT. Schumacher(Dept. of Phys.,Carnegie Mellon Univ., Pittsburgh,PA 15213)
The firstcomputer simulations of bowedstring oscillations were done by Mcintyreand Woodhouse in 1977.Generalizations to windinstruments followed within five years.The firstcommercial product using the principlesof thesesimulations appeared in 1994. Thistalk will givea briefhistory of thesedevelopments, and will thenconcentrate on recentwork on computersimulation of bowed stringmotion, much of which is presentedin detail by otherpapers in this and an associatedsession. the relativesuccess of bowed stringsimulations compared to simulationsof wind instrumentoscillations requires some explanation, which will be provided.The talk will concludewith a summaryof the recentwork by the authorwith JamesWoodhouse using fast computation to explorethe enormous parameterspace of the stringinstrumentalists' world.
9:00
2aMU2. Evaluationof transientsthrough observations and simulat'onsof bowedstrings. XavierBoutilion (Lab.d'A½oust. Musicale,C.N.R.S.-Universit• Paris 6, Case161, 4 placeJussieu, 75252 Paris C. edex 05, France) Despitetheir well-established importance on theperception of soundand their crucial role in music,transients are far lessstudied than steady-stateregimes in musicalinstruments. How long a transientlasts is certainlya majorquestion, among others: Is pitch variationnoticeable? How differentare transientsfrom note to note, from one instrumentto another?In order to investigatethese questions,direct and reciprocal observations will be presentedas well as variouspartial simulations: fully numericalsimulations, tests with a computer-controlledbowing machine, simulations based on transferfunctions. This varietyof approachesis aimedat sorting out what couldbe attributedto the player,the bow, the stringand the body of the instrument.The questionof adequatesignal processingor representationwill be addressedand the relationship between the transient length and the quality of theinstrument will be outlined.[Work supported in partby theFrench Ministry of Cullure.]
9:30
2aMU3. Someaspects of bow resonances--Conditionsfor speclralinfluence on the bowedstring. KnutGuettler (Norwegian StateAcad. of Music,Post Box 5190,Majorstua, 0302 Oslo,Norway) Theresonant bow seems to someextent capable of modifyingthe power spectrum of thebowed string, even during a steady-state Helmholtzmotion, where only one slippinginterval occurs during a fundamentalperiod. Longitudinal resonances in the bow hair, stronglycoupled to thetransverse vibrations of thestick, are being excited by thechanges of thefrictional force which occur during eachindividual period. in general,these velocity fluctuations--superimposed on the steady bowing velocity--show small amplitudes comparedto thoseof the stringunder the bow. In certainfrequency regions however, dependent on the bow/bridgedistance, impedances,etc., their energy content is sometimesgreat enough to causenoticeable modification of thestring velocity. Such spectral changeswould at anyrate be small,but may still bear some acoustic significance. The present analysis is basedon measurementson a violinbowed by a computer-controlledbowing machine, and supported bycomputer simulations. [Thanks are extended toDr. Anders Askenfeltfor sharing his experience in measuringbows, and to The Swedish Royal Institute of Technologyfor the use of theirbowing machineand other laboratory faeilities.]
I0:00
2aMU4. Effectsof bow-haircompliance on bowed-stringmotion. RolandPitteroff and Sames Woodhouse (Cambridge Univ., Eng.Dept., Trumpington St., Cambridge,U.K.) Bow-haircompliance is likelyto havea strongeffect on bow-stringinteraction. The firstline of evidencecomes from analyzing experimentalresults presented byeremet [L. eremet,The Physics of theV•olin (MIT, Cambridge, MA, 1985)]of thereflection and transmission•e•avlor or transversewaves on a stringincident on a bow at rest.The secondline oi' evidencecomes from simulations of thebowed string taking into account the finite width of thebow. The natureof the "differentialslipping" which may arise due to thekinemarital incompatibility of uniform bow velocity across the width of thebow and the string velocity in standardbowed-string motion(Helmholtz motion) is stronglydependent on bow-haircompliance. Simulations also demonstrate that suitable tilting of the bowcan reduce the extent to which"differential slipping" is detrimental to theestablishment of the desired string motion. Preliminary resultsof anexperimental investigation of finite bow-width effects will bediscussed.
3269 J. Acoust.Soc. Am., VoL97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3269
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 10:30-10:35 Break
ContributedPapers
10:35 excitationon six Formalization(FA), six Resorcin/formaldehyde(RE) bridges,and eight untreated(UN) maple violin bridge blanks.All the 2aMU5. Mode frequency and damping changes due to chemical bridgesexhibited three well-definedIP modesand six OP modes.Few treatments of the violin bridge. MacheleBailey and GeorgeBissinger (Phys.Dept., East Carolina Univ., Greenville, NC 27858) significantchanges were observedbetween the frequencyand damping parametersof the IP and OP mode shapes,although the RE treatedbridge Hammer-impactmodal analysis using a microphoneas a no-loadvi- exhibiteda possiblyunique doublet at -9 kHz. Sinceno modefrequency bration transducerwas performedon violin bridge blanks chemically variations>1.5% were found, even thoughthe RE treatmentincreased treatedtwo differentways to extractfree-free vibrationalmode frequen- bridge masses9.1%, it was concludedthat the combinedmass/stiffness cies, dampingsand shapesfor comparisonwith untreatedbridges. Data changesof the wood were relatedto the acousticeffects observed with weretaken for bothin-plane (IP) andout-of-plane (OP) vibrationsover a 0-20 kHz range.Average effects of thesechemical treatments on mode thesebridges [H. Yanoand K. Minato,J. Acoust. Soc. Am. 92, 1222-1227 frequencyand dampingwere determinedfrom IP and OP single-point (1992)].
Invited Papers
10:50
2aMU6. Anomalouslow-pitched tones from a bowedviolin string. RogerJ. Hanson (Phys.Dept., Univ. of NorthernIowa, Cedar Falls,IA 50614), FrederickW. Halgedahl(Univ. of NorthernIowa, Cedar Falls, IA 50614),and KnutGuettler (NorwegianState Acad.of Music,P.B. 5190, Majorstua, 0302 Oslo,Norway)
With a bow force greaterthan the Schellengmaximum and carefulcontrol, it will be demonstratedthat it is possibleto produce soundson a violin of definite pitch rangingfrom approximatelya musical third to a twelfth or more below the normal pitch. The loweredpitch is in agreementwith the fundamentalfrequency of the observedharmonic series. The fundamentalitself is very weak if thesounds are produced on the open G string.Marl Kimurahas utilized the effect in performances[New York Times, 21 April 1994, p. B3, andStrings, Sept./Oct. 1994, 60-66]. Theseanomalous low frequencies(ALF) occurwhen the bow force is greatenough to preventthe Helmholtzkink fromtriggering the normalrelease of the stringfrom thebow hair. As a resultof pronouncedbow-nut and bow-bridgereflections there is at the bow a very complexstring waveform, some portion of whichregularly triggers the slippingof the string.ALF can alsobe producedon a bowedstring mounted on a steelbeam, where the motionis detectedoptically. Computer simulationis usedto showhow a stringcan be forcedto vibrateat frequencieslower than the naturalfundamental frequency of the string.
11:20
2aMU7. "Subharmonics:"An extendedtechnique for the violin. Marl Kimura (Dept.of Musicand Performing Arts Professions, Schoolof Education,New York Univ., 35 West4th Street,Suite 777, New York, NY 10012)
It hasbeen found that unusual ways of drawingthe bow on the violincould produce pitches that are as low asone octave below thefundamentals. The techniquewas developed from a bowingexercise meant to improvesound production by scratchingharder on the string.After muchpracticing, all theaudible transient noises were eliminated including the fundamentals, so that only those lower notescould be heard. Then the sounds were polished into steady, clear, and loud "subharmonic" pitches, suitable for musicalpurposes. It was not until April 1994, that these"subharmonics" were publicly introducedas a musicalelement at Kimura'sNew York debut recitalin the thirdmovement of ALT for soloviolin by Kimura,which will be performedduring this presentation.In ALT, "subhar- monics"were incorporated into the music,requiring precise control of the bow in orderto freely switchbetween the new technique andthe usual bowing. The musicaleffect was noted as a "revolutionarybowing technique... astonishing effect" [E. Rothstein,The New YorkIimes (21 April 1994)].It wasalso found that seconds and thirds below the fundamentals can be producedin a similarmanner [R. Neuwirth,Strings, Sept./Oct. (No. 44, 1994)].
3270 d. Acoust.Soc. Am., Vol. 97, No.5, Pt.2, May1995 129thMeeting: Acoustical Society of America 3270
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp WEDNESDAY MORNING, 31 MAY 1995 GRAND BALLROOM SOUTH, 7:45 TO 11:45 A.M.
Session 2aPP
Psychologicaland PhysiologicalAcoustics: Auditory Perception and Physiology(Poster Session)
Donna L. Neff, Chair BoysTown National ResearchHospital, 555 North 30th Street,Omaha, Nebraska 68131
ContributedPapers
All posterswill be on displayfrom 7:45 to 1! :45 a.m.To allowcontributors an opportunityto seeother posters, contributors of odd-numberedpapers will be at theirposters from 7:45 to 9:45 a.m.and contributors of even-numberedpapers will be at theirposters from 9:45 to 11:45 a.m.
2aPPI. The effect of extraneousstimuli on sample discriminationfor hasbeen to presentthe signalto oneear andidentical muskets to bothears frequency. DonnaL. Neff andChristina I. Kessler (BoysTown Natl. withthe masker leading in time(8 ms)in theear contralateral to thesignal. Res.Hosp., 555 N. 30thSt., Omaha,NE 68131) [Worksupported by NIIt.]
Four listenerscompleted 21FC sample-discriminationtasks for fre- quency(SDF), in whichthey judged which of two tonesor tonepairs was 2aPP3. The influence of pattern-based frequency expectationson drawn from the higherof two frequencydistributions. The distributions resolving power for componentsof multitone sequences. Gary R. wereseparated in meanfrequency by 200 Hz (100-Hz s.d.}.The main Kidd (Dept. of Speechand Hear. Sci., IndianaLlniv., Bloomington, IN conditions examined SDF at 2100/2300 Hz, in isolation or with random- 47405) frequencytones (Gaussian distributed, 100 Hz s.d.),fixed-frequency tones, The effect of deviatiotfsfrom frequencyexpectations on resolving or noisebands (600-Hz wide) added on bothsides of theSDF region,or a power for componentsof tonal sequenceswas studiedwith a method singlerandom-frequency tone added on the highor low side.Stimuli were similar to that used earlier to determinethe effect of temporal deviations equatedin totalpower. Frequency position of theextraneous stimuli rela- [G. R. Kidd,I. Acoust.Soc. Am. 95, 2966(A)(1994)]. In a same-different tive to the SDF regionwas varied.Flanking random-frequency tones pro- task, listenerswere asked to comparethe last two of four twelve-tone ducedthe largestdecrements in performance,with mostlisteners showing patternspresented on eachtrial. The firsttwo patternswere identical and little recoveryeven at maximumdistance from the SDF region.A single servedto establishexpectations from which the third and fourthpatterns random-frequencytone below the SDF regiondegraded performance more coulddeviate. In the third pattern,the frequencyof a single"target" tone than one presentedabove. Flanking fixed-frequency tones also produced waslowered by either3 or 7 semitones,or left unchanged.The frequency largeperformance decrements that were relatively independent of distance. changeto be detectedwas addedto the targetcomponent in the fourth Noisebands produced little interferenceunless they overlapped the SDF patternon half the trials.Thresholds for this frequencyincrement were estimatedfor eachdeviation condition (as definedby the target-tonefre- region.Thus SDF can be affectedby distantextraneous tonal stimuli, quencyused in the thirdpattern). Just as with deviationsfrom temporal particularlythose sharing similar patterns of variation.[Work supported by expectations,deviations from frequency expectations produced threshold NIDCD.] incrementsthat increasedwith the size of the deviation.These findings suggestthat the superiordiscriminability typically observed with familiar 2aPP2. Informational masking in the identification of simple patternsis dueto theappropriate targeting of attentionin frequencyand in auditory patterns. GeraldKidd, Jr., TanyaL. Rohtla,and ChristineR. timeduring pattern presentation. [Work supported by NIDCD.] Mason (Dept.of Commun.Disorders, Boston Univ., 635 Commonwealth Ave., Boston, MA 02215)
2aPP4. Modelingthe perceivedurgency of multilonesignals. Ellen Listenersidentified six auditorypatterns comprised of eightsequential C. Haas (Human Researchand EngineeringDirectorate, U.S. Army tone bursts[cf. Kidd et al., J. Acoust.Soc. Am. 95, 2916(A) (1994)]. ResearchLab., Bldg. 520, AberdeenProving Ground, MD 21005) and Severalfactors affecting performance were examined including center fre- JudyEdworthy (Univ. of Plymouth,Plymouth, United Kingdom) quency,level andthe sizeof the frequencysteps forming the patterns.In maskedconditions, a multitonemasker was playedsynchronously with In some environments,there is a seriousmismatch between the per- eachpattern element. The componentsof the multitonemusket were cho- ceived(psychoacoustic) urgency of a warningand its situationalurgency sen randomlyon every burstwithin a presentationinterval. Musket com- (the urgencyassociated with the situationor conditionthat the signal ponemswere excluded from a regionof 20% of the patterncenter fre- represents).Several parameters which were believedto affectthe per- quencyto minimize"energetic masking." The resultsin quiet indicated ceivedurgency of multitoneauditory warning signals were investigated in that identificationperformance was nearlyperfect for patternfrequency a factoriaiexperiment. These parameters were fundamentalfrequency stepsas small as I% and at levelsas low as 20 dB SL. Considerable (200, 500, and 800 Hz), time belwecnsignals (0, 300, and 500 ms), and "informationalmasking" was produced by the randommultitone musket signallevel (5, 25, and40 dB Lin SPLabove the ambient noise level of a bursts.The maskedidentification-level functions were shallow,rising on sound-treatedchamber). The stimuliwere 27 auditorysignals, each signal averageabout 2% perdB. Several signal and masker presentation schemes consistingof a trainof fourrepetitions. Free-modulus magnitude estima- were examinedthat were intendedto reduce the observedmasking. To tion quantifiedthe relationshipbetween auditory signal parameters and date,the mosteffective means for improvingsignal pattern identification changesin perceivedurgency. The effectof the threevariables on per-
3271 d. Acoust.Sec. Am., Vol.97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3271
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp ceivedurgency will be discussed.The resultsof this experimentwill be 2aPP8. Pitch perceptionbased on a temporal energy rate model. usedin the developmentof a mathematicalmodel in whichthe relationship Henning Reetz (AllgemeineSprachwissenschaften, Univ. of Konstanz, betweensignal parameters and perceived Urgency can be defined. Postfach5560 (D186),D-78 464 Konstanz,Germany)
2aPPS. IWAIF model predictionsof a profile analysistask. Mark A. Theoriesabout the mechanismsof human'spitch perception either are Ericson,Lawrence L. Feth (Dept. of Speechand Hear. Sci., Ohio State basedon the temporalfiring rate of the haircellsin the basilarmembrane Univ.,Columbus, OH 43210),and AshokK. Krishnamurthy(Ohio State or on the placeof thesecells in the membranein a sortof spectralrepre- Univ., Columbus,OH 43210) sentation.The insensitivityto the phaseof individual componentsof a complex signal and the ability to perceivepitch for binauralpresented A profile analysistask was chosento test the predictionsof a multi- harmonicshas given experimentalevidence for place-basedpitch percep- channel1WAIF model.A 2Q, 2AFC three up-onedown, adaptivestaircase tion models.This paperexplains theses findings with an alternativetem- procedurewas incorporated with a 20-dB rovingsignal level to determine poral rate model.The proposedexplanation is basedon a mode] of the the detectionthreshold of a 1-kHz targettone in eachprofile. The musket •nner ear that computesthe energyof an acoustics•gnal in the time do- profilesincluded 11 adjacent of the21 possiblecomponents ranging from main,leading to a temporal•nergy distribution of thesignal. This temporal 200 to 5012 Hz. The componentsof the profilewere spacedlogarithmi- energydistribution is convertedby a simpledecision logic to a pitchvalue. cally at frequencyratios of 1:1.18 so that no two componentsfell into any The modelwill be theoreticallydiscussed, reanalyses of reportedexperi- onecritical band. The fixed frequency target tone was placed at eitherthe mentalfindings are presented, new experimental evidence for theproposed secondlowest, middle, or secondhighest component in each11 component modelwill be g•ven,and a computerprogram to determinethe pitch of a profile.The IWAIF modelpredictions are compared with Channel theory speechsignal based on the model'sprinciples will be evaluated. predictions[Durlach et el., J. Acoust.Soc. Am. 80, 63-72 (1986)] for 2aPP9. Effects of interaction of low- and high-frequency tone listenerperformanc e in the profileanalysis task. [Work supportedby complexeson periodicity pitch perception. Sridhar Krishnamurtiand AFOSR.] Iohn W. Hawks (Schoolof SpeechPathol. and Audiol., Kent StateUniv., 2aPP6. Identification of the incremented component in profile Kent, OH 44242) stimufi. Hedwig Gockel and Hans Colonius (GraduateCollege The effectsof interactionof low-frequencytone complexes and high- "Psychoacoustics,"FB 5, Dept. of Cogn. Psychol.,Carl-von-Ossietzky frequencytone complexes on the thresholdsof discrimination(DLs) for a Univ. of Oldenburg,D-26111 Oldenburg, Germany) changein periodicitypitch in one of the two frequencyregions were studied.Stimuli were digitally constructed by summingsine waves spaced Theability to identifythe frequency ofthe incremented component in at 100- or 200-Hz intervals.The amplitudeof componentsof one of the a multitonecomplex was assessed in two conditions•both using the same interactingcomplexes was fixed while the periodicitypitch of the other 11-tonecomplexes (fixed frequency, equilog spaced, random phases). All complexwas obtainedby decrementingamplitude of componentsin l-riB componentshad equal amplitude,except one of the inner 9, which was steps.DLs wereobtained for (1) low-frequencycomplexes only, (2) high- incremented.The overalllevel was randomlyvaried on eachpresentation. frequencycomplexes only, (3) low-frequencycomplexes in thepresence of In conditionA the tonecomplex, with the incrementposition randomized• high-frequencycomplexes, and (4) high-frequencycomplexes in thepres- was followedby a sinusoldeither at the incrementfrequency or at that of ence of low-frequencycomplexes. Preliminary results indicate elevated an adjacentcomponent (below or above).In conditionB thesame complex DLs for high-frequencycomplexes in condition2 andelevated DLs (sig- with flat power spectrumwas additionallypresented on each trial. The nificant interference effects• in conditions 3 and 4. Interference effects sequenceof flat and incrementedprofile stimuli was randomized over the weregreater for condition4 relativeto condition3. Implicationsin terms first two presentationintervals, followed by the sinusold:In bothcondi- of temporalfine structureand envelope cues are discussed. tionssubjects had to indicatewhether the frequency 0f theincremented componentwassame or different from that of the sinusold. Thresholds for 2aPP10.Difference limens for rovedglides. JohnP. Madden (Dept.of thesetwo conditionswere estimatedby the use of an adaptiveprocedure Commun.Disorders, Univ. of' North Dakota,University Station, Grand and comparedto the thresholdsof the same subjectsin discriminating Forks. ND 58202-8040'} betweenthe flat andan incrementedprofile (with signaluncertainty). Re- sultsindicate that identification ability is at leastas good as discrimination. The studydetermined glide difference limens (GDLs) for up-glidesin several conditions and estimated how well a level-detection model of the [Worksupported by DFG.] auditoryperiphery could account for the data.Signal durations were 50. 2aPP7. Discrimination of static versus dynamic, and log versus 100, and200 ms. and the averagestimulus center frequencies were I and harmonicprofiles. CharlesS: Watsonand Ward R. Drennan (Dept.of 4 kHz. To avoid the confoundingeffect of between-stimulistatic pitch Speechand Hear. Sci., IndianaUniv., Bloomington,IN 47405) cues, the center frequenciesof the standardand target stimuli were "roved"about the center frequencies [Neill andFeth. I. Acoust.Soc. Am. "Profile" stimuliconsisting of multiple simultaneousfixed-frequency Suppl.1 87, S23 (1990•].The standardsignals increased in frequencyby sinusoidalcomponents are. more representative of naturallyoccurring 0, 200, and 400 Hz. The subject'stask was to distinguishbetween the soundsthan the spectrallysimpler waveforms more often used in psychoa- standardand a targetsignal with a greaterincrease in frequencyin a cousticexperiments. However, most naturally occurring sounds are char- 2-alternative,forced-choice task. The increasein the target signalwas acterizedbY dynamic rather than static spectra,and by harmonically varied adaptivelyuntil discriminationthreshold was obtained.The results spacedrather than the log-spacedcomponents used in mostprofile experi- for the 0-Hz standardwere consistentwith previousfindings that the ments.In preparingto studya variety of dynamicprofiles, the discdin- changein Hz at thresholdis constantacross duration in a glide-detection inabilityof staticand frequency-glide profiles was determined, using both task.The resultsfor the 200 and400 Hz standardsextend this finding m a log- and harmonically spacedcomponents. Discriminations were basedon glide-discriminationtask. The modeling resultssuggest that the auditory the detectionof an intensityincrement added to the mid-frequencycom- systemtracks gliding signals by _monitoringthe changein level of the ponentof 11-component,400-ms profiles. Each profile had a startingfre- outputof theauditory filters. [Work supported by NIDCD.] quencyrange of 200to 2000Hz. Dynamicprofiles increased in frequency 2aPPll. Pitch-level functions for pure tones in the presenceof continuouslyover their400-ms durations. Each subject was mn underfour partial masking. Edward M. Bums (JG-15, Univ. of Washington, stimulusconditions (static-log, static-harmonic, dynamic-log, dynamic- Seattle, WA 98185) harmonic)generally for a minimumof 2000 trialsper condition,in an adaptive-trackingprocedure. Mean differences between asymptotic thresh- Thepurpose of thisexperiment was to determineif thepitch changes oldsfor the stimulus conditions were small compared todifferences among of pure toneswith changesin level are dependenton the spreadof exci- the subjects,Harmonic yielded somewhat lower thresholdsthan the log- tationwith increasinglevel. Pitch-levelfunctions were obtainedin quiet, spacedcomponents, while very modest differences, if any, were found andin the presenceof band-rejectmasking noise, for frequenciesranging betweenstatic and dynamic profiles. [Work supported by grantsfrom NIH/ from250 to 8000Hz. Boththe spectrum level of themasking noise and the NIDCD and AFOSR.] widthof thethe band-reject region surrounding the pure tones were pare-
3272 J. Acoust.Soc. Am., Vol. 97, No.5, Pt.2, May1995 129thMeeting: Acoustical Society of America 3272
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp metricallyvaried. In addition,estimates of the amountof partialmasking for the othermaskers. This indicatesthat the weightapplied to the signal for eachcondition were obtainedfrom loudnessmatches. Preliminary re- channel is high when the masker level is low and vice versa for the suts sugest that,for levelsabove 60 dB SPL, the pitchshifts associated correlatedmasker, but is approximatelyconstant for single-bandand un- with partialmasking usually reduce or eliminatepitch changes with level. correlatedmutliband maskers. This findingprovides direct evidencethat [Work supportedby NIDCD and the VirginiaMerrill BloedelHearing CMR is mediatedby "listeningin thevalleys." [Work supported by NIH- ResearchCenter.] NIDCD R01DC00187.]
2aPPI2. Frequency discrimination in noise by untrained listeners. 2aPP15. Temporal resolutionand CMR can depend upon frequency. Lynne A. Werner (Dept. Speech & Hear. Sci., IG-15, Univ. of Sid P.Bacon and Jungmee Lee (Psychoacoust.Lab., Dept. of Speechand Washington,Seattle, WA 98195) Hear.Sci., Arizona State Univ., Tempe,AZ 85287-1908)
The frequencydiscrimination performance of adults,with no prior An estimateof temporal resolutioncan be obtainedby subtractingthe experienceas listenersin psychoacousticexperiments, was examinedfor signalthreshold obtained in the presenceof a modulatedmasker from that tonesof 10130and 4000 Hz presentedin a backgroundof broadbandnoise. obtainedin the presenceof an unmodulatedmasker (yielding the The toneswere presentedat a signal-to-noiseratio expectedto produce modulated-unmodulateddifference, or MUD). An estimateof comodula- 80% correct detection. The level of the stimuli was either 45 or 60 dB SPL. tion maskingrelease (CMR) canbe obtainedby measuringthe MUD with The subjectswere testedin a proceduresimilar to one used in infant both a broadbandand critical-bandmasker. The presentstudy obtained psychoacoustics[Olsho et el., Devel. Psychol.23, 627-640 (1987)]. MUD andCMR for signalfrequencies from 250 to 4000 Hz. The masker Thresholdvalues of Af were found to be more similar to thoseof well- was unmodulatedor sinusoidallyamplitude modulated at ratesfrom 2 to trained listeners at 4000 Hz than at 1000 Hz. The effects of stimulus level 16 Hz. For all rates and both masker bandwidths,the MUD increased weresimilar to thosereported by Dye andHafter [J. Acoust.Soc. Am. 67, monotonicallywith signal frequency;it was larger for the broadband 1748-53 (1980)] for well-trainedlisteners: Threshold Af increasedwith masker,indicating an across-channelCMR. The CMR increasedfrom a increasinglevel at 4000 Hz, but not at 1000 Hz. This resultsuggests that few dB at 250 Hz to 14 dB at 4000Hz. Thefrequency effect (for MUD and the effectsof level on frequencydiscrimination in noiseare robustenough CMR) was considerablyreduced when the modulationdepth (m) of the to be replicatedin subjectswith little listeningexperience. Further, the maskerwas decreasedfrom 1.0 to 0.9, and was essentiallyeliminated at a effectsof level on humaninfants' frequencydiscrimination in noise may depth of 0.5. The resultsof a forward-maskingexperiment using the un- provideimportant information about why theirfrequency discrimination in modulatedmasker at both maskerbandwidths suggest that the frequency quietis moreadultlike at highfrequencies. [Work supported by NIDCD effect is due to differencesin the recoveryof forward masking,and that DC00396.] suppressioncan influenceCMR (and MUD) at very large modulation 2aPP13. On the perceptual asymmetry in frequency modulation depths.[Work supported by NIDCD.] discrimination. Tao Zhang, Lawrence L. Feth, and Ashok K. 2aPP16, Modeling modulationperception: Modulation low-passfilter Krishnamurthy(Dept. of Speechand Hear. Sci. & Elec.Eng., Ohio State or modulation filter bank? T. Dau, B. Kollmeier (GraduateCollege Univ., Columbus,OH 43210) 'Psychoacoustics',FB 8, Postbox2503, University of Oldenburg,2611l Oldenburg,Germany), and A. Kohlrausch (IPO, Eindhoven,The Severalresearchers have observed perceptual asymmetry in frequency Netherlands) modulationdiscrimination experiments. Porter et el. (1991) foundthat whenlistening to a formanttransition followed by a frequencyplateau, listenersdetected the onsetfrequency much better for the falling transition In currentmodels of modulationperception, the stimuliare first filtered than for the risingtransition. Demany and McAnally (1994) discovered and nonlinearlytransformed (mostly half-wave rectified).In order to that the frequencydifference limen measuredat frequencymaxima of a modelthe low-passcharacteristic of measuredmodulation transfer func- 5-Hz cosinefrequency modulation is significantlysmaller thhn at fre- tions,the next stagein the modelsis a first-orderlow-pass filter with a quencyminima. Hell et el. (1992) alsoobserved asymmetry in the FM typical cutoff frequencyof 50 to 60 Hz. From physiologicalstudies in responsein chickauditory cortex. They proposedthat this effect was due mammalsit is known that many neuronsin, e.g., the inferior colliculus, to the asymmetricallateral inhibition in the unit. Preliminaryresults in this show a bandpasscharacteristic in their sensitivityto amplitudemodula- lab indicatedthat this perceptualasymmetry also exists when listeners tion. Resultsfrom psychophysicalstudies of modulationmasking also were asked to discriminatebetween a sinusoidalplus linear ramp fre- suggestsome kind of bandpassanalysis of modulationfrequencies. Results quencymodulation (SLRFM) and a linear ramp frequencymodulation of two experimentson modulationdetection that allow discriminationbe- (LRFM) (Zhanget el., 1994). In this presentation,perceptual asymmetry tweenmodels incorporating a low-passfilter andthose using a modulation is systematicallystudied for bothrising and falling LRFMs. The effectof filterbankare presented.In the first experiment,modulation detection thresholds were measured for noise carriers of bandwidths between 3 and startingphase of a SLRFM signal is also examined.The experimental resultsare discussedin terms of existing modulationmodels and physi- 6000 Hz. In the secondexperiment, modulation detection for a sinusoidal ologicalexplanations. [Work supported by AFOSR.] carrier was measuredin the presenceof interfering modulationcompo- nentswith a bandpasscharacteristic in the modulationspectrum. The re- 2aPP14. Stimulus-driven, time-varying weights for comodulation sultsfrom theseexperiments could not be simulatedby a modelincluding maskingrelease. 'S•ren Buus (Commun. and Digital Signal Processing a modulationlow-pass filter, but weresuccessfully simulated by a model Center,Dept. of Elec.and Comput. Eng., 409 DA, NortheasternUniv., 360 usinga modulationfilterbank. HuntingtonAve., Boston,MA 02115-5096), Lei li Zhang,and Mary Florentine (NortheasternUniv., Boston,MA 02115) 2aPP17. Gating effectsin CMR. J.W. Hall, III, J. H. Grose,and D. R. Hatch (Div. Otolaryngol./Head& Neck Surgery,Univ. North Carolina This studytests the hypothesi•that CMR is mediatedby "listeningin at ChapelHill, ChapelHill, NC 27599-7070) the valleys"[S. Buus,J. Acoust.Soc. Am. 78, 1958-1965(1985)]. De- tectabilitywas measuredfor signalsconsisting of 6 consecutive25-ms, CMR is sometimessmaller for gated than continuousmaskers. Our 1-kHz tone burstspresented in a 50-Hz wide maskeror in maskerscon- currentwork on CMR for multiple,comodulated narrow noise bands in- sistingof seven50-Hz wide noises,one criticalband apart, with either dicatesthat the gatingeffect is minimizedwhen the numberof comodu- correlatedor uncorrelatedenvelopes. Each burstvaried randomly around lated bandsis large.The presentstudy extends this work to the CMR maskedthreshold according to Gaussiandistributions with 3- or 6-dB paradigmwhere pure tone signalthresholds are obtainedas functionof standard deviations. For each listener and condition, the responsesfrom modulated and unmodulated noise bandwidth. Results indicate that in un- 5000 trialswere sorted to constructconditional psychometric functions for modulatednoise, gered and continuousthresholds do not differ, regardless d' as a functionof burstenergy for l0 rangesof short-termlevel of the of noisebandwidth. In modulatednoise, thresholds are often higherfor on-frequencymasker band during the burst.The slopesof thesefunctions gatednoise than continuous noise when noise bandwidth is narrow,but not for three normal listenersdecrease markedly with increasingshort-term when the noise bandwidthis considerablywider than the auditoryfilter maskerlevel for the correlatedmultiband masker, but are largelyconstant bandwidth. These results may suggestthat gating effects on CMR are
3273 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3273
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp generallysmallwhen comodulation informatio• isavailable across alarge 2aPP21. Concurrent amplitude modulation detection with two numberof auditorychannels. Results will be discussedin termsof com- carriers.Stanley Sheff and •illiam A. Yost(Parmly Heating Inst., petingcues for auditorygrouping. [Research supported by AFOSR.] Loyola Univ., 6525 N. SheridanRd., Chicago,IL 60626)
2aPPIS. Multiband detectionof energy fiuctuat'ons. J.H. Oroseand The ability to detectamplitude modulation (AM) of two concurrent J. W. Hall, III (Div. Otolaryngol./Head& Neck Surgery,Univ. North Carolinaat ChapelHill, ChapelHill, NC 27599-7070) tonal carrierswas measuredin a 4 AFC task; each carrier was indepen- dentlymodulated during one of two observationintervals. Carrier frequen- cies were 700 and 2350 I-[z and AM rates were 4, 16, and 200 Hz. In the The filteringproperties of theear permitthe auditoryperiphery output concurrentdetection task, the modulationdepths were either 1.0 or set for to be viewed as a bank of parallelquasi-independent channels. The pur- a detectiond' of 0.7 or 2.0 with modulation ofjust one carrier. Results poseof thisstudy was to examinehow informationcontained among the showedlarge performance derrements in the concurrent detection proce- independentchannels is combined.Four related experiments were under- takenin whichthe detectionof an energychange within a channelwas durethat were greater than typically obtained in othertwo-channel listen- measuredas a functionof the numberof channelscarrying that change. ing tasks.Partitioning of the'4X4 responsematrix indicatedinteraction Eachexperiment examined the detection of a differentsignal type: (1) The betweencarrier channelswith performancegenerally better when both detectionof multitonesignals masked by narrowbands of noise;(2) the toneswere simultaneouslymodulated and for mostsubjects at the greater detectionof intensityincrements (intensity discrimination) for multiple modulationdepths when both responseswere correct.Cross-channel esti- mates of correlation derived from the bivariate normal distribution were noisebands;(3) the detectionof intensitydecrements for the samestimuli as(2); and(4) thedetection of temporalgaps in multiplenoisebands. Eight highlydependent on the subject'sresponse strategy. When bothtones were normal-hearinglisteners participated and performance was measured for a modulatedat the samerate, results are consistent with pastwork indicating 1-, 2-, 4-, and 8-channelstimulus. The centerfrequencies for the 8 chan- difficultyassociating modulation with its appropriatecarrier. Overall re- nels were 356, 494, 663, 870, 1125, 1442, 1838, and 2338 Hz. For each suits indicatelimited ability to independentlyprocess two concurrent signaltype, performanceimproved with increasingnumber of channels sourcesof modulationinformation. [Work supported by NIH.] carryingthe signal.The comparativepatterns of improvementwill be dis- cussedin termsof multibanddetection models. [Work supportedby the 2aPP22, Identification of fiat-spectrum vowels on the basis of NIDCD R01-DC01507.] amplitude modulation. Brian C. J. Moore and JosephI. Alc•ntara (Dept. of Exp. Psychol.,Univ. of Cambridge,Downing St., Cambridge 2aPPI9. Synthesis of common-envelope signal pairs. Iayanth CB2 3EB, England) Ananthamman,Ashok K. Krishnamurthy,and Lawrence L. Feth (Depts. of Elec. Eng. & Speechand Hear. Sci., 2015 Nell Ave., Ohio StateUniv., Columbus,OH 43210) Theseexperiments investigate whether amplitude modulation of "for- mants"allows vowel sounds to be identified.The pexiodiecomplex sounds had a fundamentalfrequency of 100 Hz and a level of 85 dB SPL. Har- A large classof soundscan be describedin termsof rapid pressure monieswere addedeither in cosineor randomphase. Harmonics with fluctuationsknown as the "fine structure"and relatively slower amplitude frequenciesbelow 3000 Hz wereequal in meanamplitude. Three pairs of changescalled the "envelope."Signals having the sameenvelope and successive harmonics, located at the first, second, and third formant fre- occupyingthe samerange of frequencies,but differingin theirfine struc- ture, are importantto the study of fine structureperception. Voclcker's quencyvalues of six possiblevowels, were sinasoidallyamplitude modu- [Proc.l]EEE 54, 340-353,735-755 (1966)]complementary two-tone lated.For a 10-Hz modulationrate, vowel identificationof cosine-phase complexpair is one of the simplestsignals in this class,and has been used stimuliimproved with increasingmodulation index, m, t3pto m=0.4• after in a numberof pitchrelated experiments. As an extensionof theseideas, a which it reachedan asymptoteof about 80%. For the random-phase computationalalgorithm is describedto generatea common-envelopepair stimuli,performance was essentiallyat chancefor all modulationdepths, occupyingthe samerange of frequenciesof any bandlimitedsignal. Sev- despitethe fact that the amplitudesof the "formant" harmonicswere eral propertiesof common-envelopesignals are presentedand methodsof greaterthan thoseof "background"harmonics at certainpoints of the combiningthese signals to createother common-envelopesignals are modulationcycle. For a 2-Hz modulationrate, performance improved for given.A few examplesof multicomponentcommon-envelope signals are the random-phasestimuli, but remainedbelow that for the cosine-phase spectrallyreversed linear-spaced complexes, spectral ramps, and multiple stimuli.Modulating the "formants"at differentrates or modulatorphases Voelckertwo-tone pairs. Applications of thesesignals to psychoacoustic madeperformance worse for random-phasestimuli but hadlittle effectfor experimentsare discussed. [Work supported by AFOSR.] cosine-phasestimuli. The resultsare interpretedin termsof the ouchlear- filteredwaveforms and in termsof perceptualgrouping mechanisms. 2aPP20.Roughness and the criticalbandwidth at low frequency. Jian-YuLin and William Morris Hartmann (Dept. of Phys.,Michigan 2aPP23. Effects of amplitude envelopeexpansion and compression StateUniv., East Lansing, MI 48824) on nonsense sentence recognition. Richard L. Freyman, Debra Speicber,and G. PatrickNerbonne (Dept. of Corntuna.Disorders, Univ. A plausiblemodel represents the sensationof roughnessas the product of Massachusetts,6 Arnold House,Amherst, MA 01003) of three factors,a speedfactor that increaseswith increasingmodulation rate,a temporalmodulation transfer function (TMTF), and a spectralwin- dow thatis determinedby auditoryfilter widths.At highsignal frequency, When spectralinformation in speechis obscured,listeners presumably wherecritical bands are broad, the TMTF is thecontrolling factor. ,A.t low fall back on secondarycues suchas thosecontained within the gross signalfrequency the auditoryfilters dominate. Therefore, roughness ex- waveform envelope.This study examined the extent to which listeners' perimentscan serve to measurethe criticalbandwidth at low frequency.To ability to use suchcues is resistantto distortionsof the envelope.Signal implementthis idea, listeners adjusted both the modulation rate f•)r AM correlatednoise samples, created individually to follow the amplitudeen- signalsand the beatrate of beatingsine pairs in orderto achievemaximum velopesof 200 nonsensesentences, were used as maskersof those sen- roughness.The center frequencyvaried from 2000 to 70 l-Iz, and SPLs tences,with signal-to-noiseratios of -4, -2, 0, and +2 dB. The resulting were 60 and 80 dB. The data could be fitted with a model in which waveformspreserved the originalwideband envelopes, but spectralinfor- roughnessis summedover all auditoryfilters. The data requirethe critical marionwas degradedto a degreedetermined by the S-N ratio. The sea- bandwidthparameter to continueto decreasewith decreasingfrequency tenceswere presentedmonaurally to normalhearing subjects at 70 dB below 500 Hz sothat it becomesconsiderably narrower than critical bands SPL. Recognitionof key wordsin thesesentences was compared to that fromthe bark scale. [Work supported by theNIDCD.] obtainedfor waveformsthat had been processed with two differentlevels
3274 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3274
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp of amplitudeexpansion and two levelsof compression.The resultsindi- noise-replacedspeech was shorter than when no replacementwas made. catedthat amplitude expansion severely reduced recognition scores, while The apparentduration of gap-replacedspeech was also measured in this compressionhad little effect. [Work supported by NIH #DC01533.] experiment.The degreeof underestimationwas far greaterfor the latter case.These findings suggest that a shrinkageof durationoccurs in the 28PP24. Defining features of steady-statetimbres. Michael D. Hall processof resyntbesizingan "auditoryobject" where the processis as- (Dept. of Speechand Hear.Sci. Wl-10, Univ. of Washington,Seattle, WA sumedto be at a differentstage than that utilizingspeech-specific schema. 98195) and RichardE. Pastore (Dept. of Psychol.,State Univ. of New York at Binghamton,Binghamton, NY 13902-6000) 2aPP27. The effects of incremental change in temporal envelope correlation on auditory fusion. John R. Carter, Patrick W. Rappold While several dimensions contribute to voice and instrument timbre, (Dept.of SpeechPathol. and Audiol., Univ. of SouthAlabama, Mobile, AL perceptualinteractions between dimensions have not beenadequately as- 36688),and MadhuffS. Muelkar (Univ.of SouthAlabama, Mobile, AL sessed.As a result, the information used in timbre identification is unclear. 36688) Three experimentssought to definesteady-state timbrai features.First, Gamerclassification reflected the perceptualintegrality of spectralslope The effects of incrementalchange in degreeof temporalenvelope andformant structure (a sourceand filter property, respectively); classifi- correlationon theauditory fusion of narrow-bandnoise (NBN) pairswas cationspeed along either dimension depended upon variability along the examinedby placingfusion in competitionwith sequentialstreaming for other dimension.Feature detection then was evaluatedwithin arraysof one componentof a NBN pain Sevenlevels of envelopecorrelation were distractorpitches with homogeneoustimbre. When targets had/{ff vowel represented(r= 1.0,0.75, 0.50,0.25, 0.00, -0.25, -0.35) by threesets of formantswith shallowspectral slopes, search time increasedas a log func- NBN pairs,for a total of 21 NBN pairs.A NBN pair consistedof a tion of array size consistentwith parallelprocessing. Parallel search was target-bandspectrally centered at 2000 Hz, and a flanker-bandcentered at not obtainedfor targetswith /i/ formantsand steepslopes, suggesting a 1500 Hz. A NBN pair was playedalternately with the target-bandalone feature coded as the presenceor absenceof /a/ formants with shallow (captor-band)at an initial interstimulus-interval(ISI) of 500 ms.The ISI slopes.A final searchexperiment using heterogeneous distractor timbres decreasedautomatically in 5- or 2-msincrements until a subjectexited the showedthat this featurewas separablefrom pitch. Searchtimes for con- programwhen judging the perceptualprominence of sequentialstreaming junctionsof pitchand timbre linearly increased with arraysize, implying as greaterthan that of fusion.The ISI at exit wasused to infer strengthof serialprocessing. Thus attention was neededto conjoinattributes to per- fusion for the NBN pain ShorterISis suggestedstronger fusion; longer ceivetonal objects. Implications are discussedfor the natureof attention ISis suggestedweaker fusion. Results showed a trend for ISI to increase andthe perception of propertiesrelevant to communication.[Work sup- with a decreasein the degreeof envelopecorrelation, which suggested a portedby AFOSR.] gradualdecline in fusionstrength as envelope correlation was incremented downwardfrom perfectcorrelation. 2aPP25. Individual differences in speech and nonspeechprocessing among normal-hearingsubjects, Aimee M. Surprenant (Dept. of 28PP28. Attention and grouping in vowel perception. R. W. Hukin Psychol.Sci., PurdueUniv., 1364 Psychol.Sci. Bldg., West Lafayette,IN and C. J. Darwin (Lab. of Exp. Psychol.,Univ. of Sussex,Falmer, 4790%1364)and CharlesS. Watson (IndianaUniv., Bloomington,IN BrightonBNI 9QG, UK) 47405) The effective contributionof a 500-Hz componentof a steady-state While a large portionof the varianceamong listeners in auditory vowel was measuredby the positionof the vowel boundaryon a/U-/e/ speechprocessing is associatedwith the audibilityof componentsof the continuumvarying only in firstformant (FI) frequency.Shifts in thevowel speechwaveform, it is not possibleto predictindividual differences in boundarywere calibratedagainst those produced by level changesin the speechperception strictly from the audiogram. Psychoacoustic measures of 500-Hz component.When the 500-Hz componentwas givenan ITD of spectral-temporalacuity with nonspeechstimuli also have beenshown to 666 /xs and the remainingcomponents an ITD of -666 /zs, there was a correlateonly weakly(or not at all) with speechprocessing. In a replica- smallbut significantreduction in the 500-Hz component'scontribution to tion andextension of an earlierstudy (Watson et el., J. Acoust.Soc. Am. phoneticquality. When the vowel was embeddedin a sequenceof six Suppl. I 71, S73) 100 normal-bearingcollege students were testedon 500-Hz tones,each having the sameITD as the 500-Hz componentof the speechperception tasks (nonsense syllables, words, sentences in a noise vowel, therewas a significantreduction its contributioncompared to when background)and on 6 spectral-temporaldiscrimination tasks using simple all componentshad the sameITD. When the sequenceconditions were andcomplex nonspeech sounds. Factor analysis showed that the abilities presentedin the sameexperimental block as the previousITD conditions, that explainperformance on the nonspeechtasks are quite distinctfrom thenthe latterconditions did showan effectof groupingby commonITD. thosethat account for performanceon the four speechtasks. Performance Theseresults show that listenerscan groupsounds on the basisof ITD was significantlycorrelated among speech tasks, and amongnonspeech information,but their ability to do so is greatlyenhanced if the position tasks.Either, (a) auditoryspectral-temporal acuity for nonspeechsounds is andfrequency have been previously cued. [Work supported byUK MRC.] orthogonalto speechprocessing abilities, OR (b) we haveyet to identify 2aPP29. A comparisonof two proceduresfor studying auditory theappropriate task or typesof nonspeechstimuli that exercise the abilities image formation. RichardA. Roberts,Patrick W. Rappold,Michael P. requiredfor speechrecognition. [Work supported grants from NIH and Cannito (Dept. of SpeechPatrol. andAudiol., Univ. of SouthAlabama, AFOSRto IndianaUniversity.] Mobile,AL 36688),and MadhuffS. Muelkar (Univ. of SouthAlabama, 2aPP26. Shrinking illusion of speechduration caused by noise/gap Mobile, AL 36688) replacement. Minoru Tsuzaki and Hiroaki Kato (ATR Human InformationProcessing Res. Labs., 2-2 Hikaridai,Seika-cho, Soraku-gun, The resultsfrom an off-line procedure(scaling) were comparedto Kyoto, 619-02 Japan) thosefrom an on-lineprocedure ("rate adjustment")for effectivenessin examiningthe fusion strength of partialswithin two, three-tone complexes. To investigatethe processof perceptualresynthesis of an "auditory In bothprocedures fusion strength was inferred by thecase in whicha tone object,"the apparentduration of a noise-replacedspeech signal was mea- presentedin isolation(captor tone), and alternately with a complex,was sured.Subjects adjusted the duration of synthesizedspeech to subjectively ableto capturea member(target tone) of the complexinto a sequential matchthat of the targetspeech. When a portionof the targetspeech was stream.In the rateadjustment procedure the interstimulus-interval(ISI) replacedby a noiseburst, the durationwas perceived to be shorterthan betweencaptor and targetwas decreaseduntil the listenerjudged the whenno replacementwas made. Besides this effect, the apparentduration prominenceof streamingto be greaterthan that of fusion.In thescaling of speechsegments was foundto be affectedby theirdeviation from the procedurethe ISI was heldconstant. On a visualanalog scale, having its internaltemplate. The greaterthe physicalduration of the targetdeviated endpoints labeled "fast" and "slow,"subjects judged the prominenceof fromthe "naturally"spoken token, the greaterthe degreeof underestima- the rateat whichthey heard the pitchof the captortone. Stimulus factors tion became.Interestingly, these two effectswere independentof each weretone relationship (octave/inoctave) and toneposition (low, middle, other.This independencewas replicated in the secondexperiment which high).More of the total variationwas explained by the rate adjustment testedwider range of durationaldeviations. Again, the apparent duration of procedure,but the coefficientsof variationfor eachtone position were
3275 d. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3275
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp smallerfor the scalingprocedure. Neither procedure showed an effectof havinga possiblecognitive origin. Data will be comparedto thoseof tonerelationship (octave/inoctave), and both procedures showed the same relatedliterature. [Work supported by BryngBringelson Foundation.] effectof toneposition. 2aPP33. Referential coding and the "severe departure" from 2aPP30. The effects of narrow-band noise maskers on overshoot. Weber's law. ChristopherJ. Flack (Dept. of Exp. Psychol.,Univ. of PeterMarvit and VirginiaM. Richards (Dept. of Psycbol.,Univ. of Sussex,Brighton BN1 9QG, UK) Pennsylvania,3815 Walnut St., Philadelphia,PA 19104) The Weber fractionfor intensitydiscrimination for a 30-ms, 6.5-kHz The elevationof detectionthresholds for a shortsignal added just after sinusoidalpedestal is greaterat mediumpedestal levels that a low or high the onsetof a maskerversus when it is addedlater duringthe maskerhas pedestallevels, particularly when the pedestalis satedwith notchednoise beencalled "overshoot."Previous work with broadbandmaskers suggests [R. P. Carlyonand B.C. L Moore, J. Acoust.Soc. Am. 76, 1369-1376 maskerfrequency component near, but not at, thesignal frequency produce (1984)]. In the presentexperiments, Weber fractions were measuredfor a overshoot.The relativecontribution of different frequencyregions to the 30-ms, 6-kHz pedestal,at a rangeof levels between40 and 70 dB SPL. overshooteffect was investigated here with narrow-bandnoise maskers of differentcenter frequencies. The350-ms maskers were «octave wide with Measurementswere madein quietand in the presenceofa 110-msnotched centerfrequencies ranging from 1400to 8500 Hz. The 10-mssignal was noisewith an onset40 ms beforethe onsetof the pedestal.The bandstop 2500-Hz tone added 4 or 325 ms after the onset of the masker. Masker portionof the noisewas l-kI-Iz wide, centeredon 6 kHz, and the noisehad spectmmlevels were 35 dB SPL. The three subjectsgenerally showed a fixedspectrum level of 20 dB. In contrastto the earlierresults, at pedestal little or no overshootwhen the masker spectrally overlapped the signal,but levels of around 50 dB SPL the notched noise caused a reduction in the 1 showeda maximumovershoot of 8-12 dB for maskerbands centered • to Weberfraction. It is suggestedthat the noisemight improve performance I octaveabove and below the signalfrequency; increased signal-masker by providinga proximalreference for codingthe intensityof the pedestal. frequencydifference diminished but did not abolishthe overshooteffect. [Worksupported by The Royal Society.] Detectionthresholds were maximalwhen the maskerband spectrally over- lappedthe signaland fell as signal-maskerfrequency separation grew. A 2aPPM. Short-term tempo.ral integration at high-frequencies: similarpattern of resultswas obtainedusing low-pass, high-pass, band- Evidence for the influence of peripheral nonlinearity? Andrew J. pass,and notchednoise maskersbounding on a 750-Hz-wide region Oxenham and Brian C. L Moore (Dept. of Exp. Psychol.,Univ. of aroundthe 2500-Hz signal frequency. [Work supported by NIH.] Cambridge,Downing St., CambridgeCB2 3EB, UK)
2aPP31. Forward-maskedintensity discrimination: Duration effects. Temporalintegration in the auditorysystem can be modeledby a com- RobertS. Schlauehand Nicole Lanthier (Dept. of Commun.Disorders, pressirenonlinearity followed by a temporalintegrator. For a fixed inte- 115 ShevlinHall, Univ. of Minnesota,Minneapolis, MN 55455) grator,the more compressirethe nonlinearity,the greaterthe effective integration.Compressire nonlinearity on the basilarmembrane is marked Forward-maskedintensity discrimination shows elevated just- at mediumlevels, but is redoecdat low and high levels.To assesswhether noticeabledifferences (jnd's), for mid-levelstandards, a finding argued to this influencestemporal integration, thresholds of a 6.5-kHz sinusoldwere be consistentwith sensory adaptation IF. Zengand C. W. Turner,J. Acoust. measuredin the presenceof a long-durationbroadband-noise masker as Soc.Am. 92, 782-787 (1992)].Accordingly, the sizeof jnd'sshould in- functionof signal duration,using tM'ee different noise spectramlevels, creasewith increasesin maskerduration. We testedthis notion by mea- suringforward-masked jnd's as a functionof level for 1000-Hz tonesin -10, 20, and 50 dB (re: 20 /zPa). Signallevel dB was plottedagainst four listenerswith norraM hearing.Jnd's were measuredfor 10-ms stan- log(time)for eachlevel. For signaldurations between 20 and200 ms,there dardsin quietand in thepresence ofa 1000-Hzmasker with either a 10-ms wasno significantdifference in theslopes of thethree functions. However, or a 250-ms duration. The masker level was fixed at 90 dB SPL and the between1 and 10 ms the slopeof the functionfor the mid-levelmasker interval between masker offset and standard onset was 100 ms. Forced- wassteeper by a factorof between1.5 and 2. This is consistentwith the choiceprocedures were employed.The resultsshow significantlyless greatermid-level compression on the basilarmembrane, ff one assumesa maskingfor the longer duration masker (250 ms) than for theshort one (10 fixedshort-term temporal integrator. Performance in otherpsychoacoustic ms).These results are contrary to the resultsreported for forward-masked tasks,including differences between normal-hearing and hearing-impaired detection.Listening bands revealed by measuringjnd's as a functionof listeners,is alsodiscussed ia termsof peripheralprocessing. [Work sup- maskerfrequency suggest that off-frequencylistening may be responsible portedby the MRC, EPSRC,and Meridian Audio (UK).] for thisfinding [Work supported by theBryng Bryngelson Fund.] 2aPP35. Temporal integration of loudness as a function of level. 2aPP32. Mechanisms underlying nonmonotonic Weber functions in Mary Florentine(Commun. Res. Lab., Dept. of Speech-LanguagePathol. forward-masked intensity discrimination. Bart R. Clement and and Audiol., 133FR, Northeastern Univ., Boston, MA 02115), Sdren RobertS. Schlauch (Dept. of Commun.Disorders, Univ. of Minnesota, Buus (Northeastern1Jniv., Boston, MA 02115), and Torben Poulsen 164 PillsburyDr. S.E., Minneapolis,MN 55455) (Tech.Univ. of Denmark,DK-2800 Lyngby,Denmark)
Nomnonotonicgrowth in thresholdfor intensitydiscrimination has This studycompared temporal integration of loudnessfor 1-kHz tones beennoted for puretones preceded by intensesinusoidal maskers; thresh- andbroadband noises. Absolute thresholds and levels required to produce olds are highestfor 40-60 dB SPL standards,producing what has often equalloudness were measured for 5-, 30-, and200-ms stimuli using adap- been describedas a "midlevel hump." Both physiologieand cognitive five, two-interval,two-alternative foreed-choice procedures. Levels ranged factorshave ben suggestedas mechanismsunderlying this phenomenon. from 5 to 80 dB SL for noises and from 5 to 90 dB SL for tones. Results Three subjectsreceived four conditionsdesigned to examinethis i•ue. A 2IFC paradigmassessed intensity discrimination of 1000-Hz, 100-mssi- for 6 listenerswith normalhearing show that the amountof temporal nusoids.A no-maskercondition provided a baseline.Three forward- integration,defined as the level differencebetween equally loud 5- and maskedconditions were implemented:An ipsilateralcondition that typi- 200-msstimuli, varies nonmonotonically with level. The averageamount cally producesa mid-level hump; a contralateralcondition in which the of temporal integrationvaries from about 10-12 dB near threshold,to a humpis typicallyabsent or greatlyreduced; and a binauralcondition pre- peak of 18-19 dB when the 5-ms tone is about56 dB and the 5-ms noise sentingthese two maskerssimultaneously (contralateral stimulation was is about76 dB SPL; at higherlevels, the amountof temporalintegration 13 dB greaterthan ipsilateralstimulation; listeners perceived only the decreases to 10 dB for tones and 13 dB for noises with levels around 100 contralateralmasker). It wasargued that if thiscondition produced a hump dB SPL. Theseresults indicate that modified power functions cannot ac- despitea pereeptuallyabsent ipsilateral masker, a sensoryexplanation count for the growth of loudnessfor tonesat all durations.They also would be suggested.Conversely, data mirroring the no-maskeror con- indicatethat the growth of loudnessmay, at leastin part,be consistentwith tralateralresults would he consistentwith a cognitivehypothesis. Results the nonlinearinput/output function of the basilarmembrane. [Work sup- suggesta strongsensory component, with only a smallportion of the effect portedby NIH-NIDCD R01DC02241.]
3276 d. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of Amedca 3276
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 2aPP36. Modeling loudness growth and loudness summation in 2aPP39. The effects of criterion variability on relative operating hearing-impairedlisteners. S. Launer,V. Hohmann,and B. Kollmeier characteristics. William S. Brown (BrookhavenNatl. Lab., Bldg. 130, (AG Mcd. Phys.,FBS, Univ. Oldenburg, Postbox 2503, 26111Oldenburg, Upton,NY 11973-5000)and DavidS. Emmerich(State Univ. of New Germany) York at StonyBrook, Stony Brook, NY 11974)
The goalof thisstudy is to modelthe effectof sensorineuralhearing The form of the relativeoperating characteristic (ROC) describing impairmenton loudnessperception for stationarystimuli of variableband- auditorydetection typically differs from that expectedbased on the as- width.Loudness growth functions were obtained employing a categorical sumptionthat the observer's responses reflect underlying distributions that arenormal and of equalvariance [e.g., Green and Swcts, Signal Detection scalingtechnique with 10 categories.Loudness scaling was performed Theoryand Psychophysics].Specifically, it is foundthat binormal ROCs with 9 normal-hearingand 14 sensorineuralhearing-impaired subjects em- oftenhave slopes less than one, and are not strictly linear [Watson et al., ployingbandfiltered noises with bandwidthsbetween 1-6 criticalbands. J. Acoust.Soc. Am. 36, 283-288 (1964)]. It has been suggestedthat For normal-bearinglisteners, categorical scaling revealed similar differ- nonlinearbinormal ROCs may be the resultof extremecriteria being more encesacross stimulus conditions as with loudnessbalancing. The loudness variablethan those more centrally positioned [Emmerich and Binder, J. functionsof the bearing-impairedlisteners show both, a steeperincrease Acoust.Soc. Am. Suppl.I 65, S59 (1979)].The formsof ratingROCs (recruitment)and reducedloudness summation. Both aspectswere suc- obtainedin an experimentdesigned to revealthe effects of suchvariability cessfullymodeled by Zwicker's loudnessmodel with threeextensions to were consistentwith the propositionthat criteriaassociated with "no" takeaccount of hearingimpairment. Raised audiometric threshold is mod- responsesare morevariable than those associated with "yes" responses. eled by a frequency-dependentattenuation after calculationof excitation Criterionoperating characteristics [Wickelgren, J. Math.Psychol. 5, 102- patterns.Increasing the exponent in calculatingthe specific loudness yields 122],which reflect the relative locations and variances of theboundaries of recruitment.Reduced frequency selectivity is accountedfor by the normal confidencecategories, favored the sameinterpretation. It is concludedthat dependenceof filter bandwidthon level in the excitationpatterns. The the variabilityof criteriadefining categories of ratedconfidence is sizable extendedmodel describes well the measuredindividual loudness growth and not necessarilyconstant across criteria, and that suchvariability sig- functionsof hearing-impairedsubjects for stimuliof differingbandwidth. nificantlyinfluences the formsof empiricalROCs determinedusing con- fidenceratings in auditorysignal detection. 2aPP37. Efficiency of selective listening by normal-hearing and hearing-impairedlisteners. Karen A. Doherty (Commun.Sci. and 2aPP40. Application of confidence intervals and joint confidence Disorders,Syracuse Univ., 805 S. CrouseAve., NY 13244)and Robert regions to the estimation of psychometric functions. Monica L. A. Lutfi (Univ. of Wisconsin,Madison, WI 53705) Hawleyand H. StevenColburn (Dept.of Biomed.Eng., Boston Univ., 44 CummingtonSt., Boston,MA 02215) A COSSanalysis procedure lB. G. J. Berg,J. Acoust.Soc. Am. 88, 149-158 (1990)] was used to estimatethe efficiency with which 15 A mathematicaldescription of a psychometricfunction with two free normal-hearingand 15 hearing-impairedlisteners detected a level incre- parametersis fit to fixed-incrementdata by a nonlineargradient search mentin a targettone embedded in a multitonecomplex. The complexwas techniquethat incorporates a weighted least squares algorithm. The statis- comprisedof 6 oct frequenciesfrom 250-8000 Hz andthe target tone was tical confidencein the parameterestimates is consideredby comparing selectedas eitherthe 250-, 1000-,or 4000-Hz tone.The hearing-impaired resultsfrom standardconfidence interval analysiswith thosefrom joint listenershad moderate, sloping, high-frequency sensorineural hearing im- confidenceregion analysis. Confidence intervals estimate the variability of pairments.Two efficiency measures were used to accountfor thelisteners' each parameteralone, ignoringthe interactionbetween the parameters, lessthan ideal performance onthe task; weighting efficiency (•w•t), which whereasthe joint confidenceregion gives the confidencein thejoint esti- measureshow well the listenerattends to or weighsthe target,and noise mationof bothparameters together. In our study,both analyses were ap- efficiency07no•), which accounts for all otherfactors unrelated to weights. pliedto fixed-incrementdata from a varietyof tests(interaural time and Weightingefficiencies were significantly higher for hearing-impairedlis- intensitydiscrimination and NoS• binauraldetection) and subjectsfor tenersthan normal-hearing listeners for the 4000-Hz target,which was in two-intervalforced choice experiments. Results show that the parameter estimatesare affectedprimarily by the datacollected near the midpoint theregion of hearingloss. No significant r/,• differencesbetween normal- whichis notsurprising since the parameters in themodel are the slope and hearingand hearing-impairedlisteners were observedfor the othertwo translationat the midpoint.However, the joint confidenceregion analysis targettones. Even though hearing-impaired listeners sometimes weighted showsthat the statisticalconfidence of the parameterestimates are greatly informationmore efficiently than normal-hearinglisteners their overall affectedby datacollected at levelsthat give performance near chance and performanceon the task was significantlypoorer as was reflectedby nearperfect. [Work supported by NIDCD(Grant DC00100).] smallervalues of r/noir. 2aPP41. Temporal symmetry in auditory perception and the 2aPP38. On measuring psychometric functions. Huanping Dai auditory system. Toshio Irino (NTY Basic ResearchLab., 3-1, (Psychoacoust.Lab., Dept. of Psychol.,Univ. of Florida,Gainesville, FL MorinosatoWakamiya, Atsugi-shi, Kanagawa, 243-01, Japan) and Roy 32611) D. Patterson(MRC Applied Psychology Unit, Cambridge CB2 2EF,UK)
Psychometricfunctions of simulatedobservers were obtained using the Whena repeatingdamped exponential is usedto modulatea sinusold conventionalconstant-stimulus method and an adaptiveup-down method or noise,the carriercomponent of the perceptionis suppressed.When througha post-hocanalysis of the track.The form of the psychometric these"damped" sounds are reversed in time,producing "ramped" sounds, functionswas assumed to bePc = •(d'/2 m), whereß is thecumulative thecarrier is restored.[R. D. Patterson.J. Acoust.Soc. Am. 96, 1419-1428 Gaussianprobability function. The detectability d', isrelated to thesignal (1994);M. A. Akeroydand R. D. Patterson,J. Acoust.Soc. Am. 95, levelx byd' =axk, where a andk arethe two parameters tobe estimated. 2941(A)(1994)]. We report matching experiments designed to measurethe Amongthe factors considered in thesimulation were step size and number pemeptualasymmetry between damped and ramped sounds directly. Lis- of trials.For smallnumber of trials(n•<120), and particularly when the tenerscompared the relative strengths of thetransient and continuous com- stepsize was also small, the slopevalues (k) estimatedusing the adaptive ponentsin pairsof dampedand ramped sounds, and the damped half life methodwere systematically greater than the true slopes. Such biases were wasvaried to producea matchin therelative strengths of thetransient and smaller with the constant-stimulus method. When the number of trials was continuouscomponents of the two sounds.For sinusoidaland noise card- reasonablylarge (n•>300), the constant-stimulusmethod showed no clear ers, the half life of the dampedsound has to be, respectively,5 and 2.5 advantageover the adaptivemethod. The only a priori informationre- timesthat of the correspondingramped sound to producethe match.A quiredin the adaptivemethod is thestarting stimulus level, whereas the "delta-gamma"theory of intensityenhancement around acoustic transients constant-stimulusmethod requires pilot measurementsin orderto set all [T. Irinoand R. D. Patterson,J. Acoust.Soc. Am. 95, 2943(A)(1994)] is thestimulus levels properly. Thus the adaptive method is reasonablyeffi- usedto explainthe perceptualasymmetry. The theoryis also usedto cientfor measuringpsychometric functions. [Work supported by NIH.] comparethe asymmetryproduced by differentauditory models.
3277 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3277
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 2aPP42. Temporally directed attending in the discriminationof 2aPP45. Binaural detectionwith reproduciblenarrow-band maskers. tempo: Further support for an entrainment model. J. Dcvin ScottK. Isabelleand H. StevenColburn (Dept.of Biomed.Eng., Boston McAuley (Dept.of Cornput.Sci., CognitiveScience Program, Indiana Univ., 44 CummingtonSt., Boston,MA 02215) Univ.,Bloomington, IN 47405)and GaryR. Kidd (Dept.of Speechand Hear.Sci., Indiana Univ., Bloomington, IN 47405) Responsesof five subjectsfor the binaural detectionof a 500-Hz, 300-ms,interaurally out-of-phase tone masked by statisticallyindependent The effectof deviationsfrom temporal expectations on tempo discrimi- samplesof narrow-band,interaurally identical noise are reported.A setof nationwas investigatedusing four-tone isochronous sequences. On each 30 noisesamples were taken from a noiseprocess with a power spectrum trial, a standardsequence was followedby a comparisonsequence that was that is 115Hz wide, centeredat 500 Hz. The rms noisepressure was 75 dB slightly fasteror slowerthan the standard.Listeners judged which se- SPL. For each subject,the responsesshow good self-consistencyand a quencewas faster. Temporal deviations consisted of advancingor delaying strongdependence on individualnoise samples. (For example intrasubject theonset of thecomparison pattern in relationto an onsetpredicted by an correlationcoefficients for subsetsof the resultswere typically0.85 and extensionof the periodicityof the standard(i.e., an "expected"onset, alwayshigher than 0.72). However,there are significantdifferences be- basedon an entrainmentmodel's predictions). The interonset-intervalin tweensubjects in thepattern of responsesacross the set of maskersamples. thestandard sequence was always 400 ms,and the onset of thecomparison (Intersubjectcorrelation coefficients were lower than 0.7). Subjects'per- sequencewas manipulated in relationto an "expected"interval of 800 ms formantevalues for individualnoise samples are comparedto the predic- betweenthe onsetof the last toneof the standardsequence and Ihe onset lions of psychophysicalmodels for binauraldetection. Sample-level pre- of the comparisonsequence. Discrimination thresholds were determined dictions of models for which the decision variable is dominated by the for conditionsin whichthe comparisonpattern onset was early, late, or at energyin the particularnoise sample have no significantcorrelation with the expectedtemporal location. Thresholds for "early" conditionswere the patternsof responsesacross noise samples for any subject.In contrast, foundto be significantlyhigher than for the "expected"condition, but this modelsthat are basedon variability of the interauraldifferences have was not the casefor "late" conditions.These data will be comparedwith predictionsthat are statisticallysignificantly correlated with mostsubjects' thequantitative predictions of an entrainmentmodel [McAuley and Kidd, responses(although no correlationcoefficients were larger than 0.7). J. Acoust.Soc. Am. 95, 3257 (1994)]. [-Worksupported by NIMH and [Worksupported by NIDCD {GrantDC00100).]
2aPP46. Infinite-Impulse-Response filter models of the head-related 2aPP43. The effect of different componentmeans and variances on transferfunction. AbhijitKulkarni and H. StevenColburn (Dept.of the discriminationof temporal patterns. Toktam Sadralodabaiand Biomed.Eng., Boston Univ., 44 CummingtonSt., Boston,MA 02215) RobertD. Sorkin (Dept. of Psychol.,Univ. of Florida,Gainesville, FL 32611) Directional-transfer-functions(DTFs) derivedfrom head-relatedtrans- Listenerswere presentedwith two successive9-tone sequences. The fer functions(HRTFs) measured from humansubjects in an anechoicen- task was to discriminatebetween the temporalpatterns defined by the vironmentwere modeled using anto-regressive (AR) andauto-regressive intertonetimes in eachsequence (tone duration=25 ms, tonefrequency moving-average(ARMA) medelingtechniques. The HRTFs,which were = 10130Hz). The listenerhad to indicatewhether the two patternshad the providedby Dr. Fred Wightman(Wightman and Kistler, 1989),were de- sameor different(partially correlated) temporal envelopes. A technique composedinto a directional-transfer-function(DTF) and a mean-function suggestedby Lutfi JR.Lutfi, J. Acoust.Soc. Am. 97, 13390995)], was (computedas the meanof all measuredHRTFs for that subject).Model usedto determinethe importanceof eachtemporal position on the listen- reconstructionsof the HRTFs was doneunder the assumptionthat HRTFs er's decision.In the first experiment,one of the intertonetimes was as- are minimum-phasefunctions. The AR estimatorwhich is derivedfrom the signeda different(either higher or lower)mean duration than the others. theoryof linear prediction,corresponds to an all-pole modelof the DTF. Thisintertone time occurred either at anearly temporal position (2nd) or at The ARIMA modelextends the all-pole modelto a pole-zeromodel and is a lateposition (6th). Results indicated that two positions,the firsttemporal derivedby posinga weighted-least-squaresformulation of the modified- positionand the positionwith the differentmean, had more influenceon least-squaresproblem proposed by Kalman(1958). The validityof each the listener'sdecision than other positions.In the secondexperiment, the model was assessedpsychophysically using a 41, 2AFC paradigm.Using first 4 intertonetimes were assigneda different variancethan the last a 80-mswhite noisestimulus and testinga differentposition on eachIrial, occurring4 intertonetimes. Initial resultssuggest that listenersgive higher for a 25-poleall-pole model and a 6-pole6-zero pole-zero model, subjects weightsto thetemporal positions with the lower variance. [Work supported performed close to chance for most of the 13 representativepositions hy ^FSOR.] tested.[Work supported by NIDCD (GrantDC00100).]
2aPP44. Detection and recognition of familiar sounds in noise. 2aPP47. Efficient finite-impulse-responsefilter models of the Mark A. Stellmack and Robert A. Lutfi (Watsman Ctr., Univ. of head-related transfer function. Abhijit Kulkami and H. Steven Wisconsin--Madison,Madison, WI 53706) Colbum (Dept. of Biomed.Eng., BostonUniv., 44 CummingtonSt., Boston,MA 02215) Three experimentscompared listeners' detection and recognitionin broadband noise of five familiar and five unfamiliar sounds with identical Thehead-related transfer function (HRTF) is empiricallymeasured as long-termspectra. The familiar soundswere ice in a glass,zipper, crashing a finite-impulse-response(FIR) filtere.g., Wightman and Kistler, 1989. In wood blocks,creaking door, and gas stationbell. The unfamiliarsounds this studywe explorereduced-order approximations of measuredHRTFs were thesesame five soundsplayed backwards. Thresholds were obtained for use in virtual acousticaldisplays. The HRTFs testedwere measured using a single-interval,yes-no procedure.In the first two experiments, from humansubjects and providedby Dr. Fred Wightman.In all model detectionthresholds were measuredfor each soundby playing the same reconstructionsit is assumedthat HRTFs can be approximatedas soundwithin eachblock of trials (fixed signal),and by playingone of the minimum phase functions. Theoretical results are derived which allow for ten soundswith equalprobabtlity on eachsignal trial (randomsignal). In Iwo model-orderreduction strategies with optimalcriteria. First, we dem- the third experiment,both detectionand recognitionthresholds were ob- onstratethat the partial energycontained in the first n tapsof a minimum- tainedfor threeof the familiar soundsplayed forward and backward.On phaseFIR filteris optimalin theParseval sense. Secondly, we demonstrate eachtrial, listenerswere asked first to makea yes/nodetection judgment thatthe HRTF expressedby itscepstral coefficients (Oppenheim and Scha- and then to identify whichsignal was playedregardless of their firstjudg- fer, 1979) constitutesa Fourierseries. A partial sum from this Fourier ment. In all three experiments,there were no significamdiffereneo.• be- •ries then providesthe best mean-squareapproximation to the log- tween thresholdsobtained for the soundsplayed forward and thresholdsfor magnitudefunction of the HRTF. The validityof the reconstructedHRTFs correspondingsounds played backwards. There was a small (1 dB) but wasassessed psychophysically using a 41-2AFC procedure.Using a 80-ms statisticallysignificant difference between thresholds for fixed and random whitenoise stimulus and testing a newposition on eachtrial, for a 64-tap signals.These resultssuggest that naturally occurring,familiar sounds HRTF reconstructionby bothmethods, subjects performed close to chance have no specialstatus among auditorystimuli in simple detectionand for mostof the 13 representativepositions tested. [Work supportedby recognitiontasks [Research supported by NIDCD.] NIDCD (GrantDC00100).]
3278 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3278
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 2aPP48. Effects of reverberation cues on distance identification in importanceof informationretention in maintainingpursuit tasks when virtual audiodisplays. DouglasS. Brungart(AL/CFBE, 2800 Q Street, targetinformation is removed.The importanceof the auditorysystem in WPAFB,Oil 45433-7901)and WilliamD'Angelo (AL/CFBA,WPAFB, processingspatial information for pursuitmovement tasks will be dis- OH 45433-7901) cussed.[Work supported by NSE]
Althoughreverberation is knownto playan importantrole in the per- 2aPP52. Evaluation of three-dimensional(3D) auditory beaconsfor ceptionof distance,it is notpossible to isolatethe effects of earlyand late navigationof remote-controlledvehicles. Tuyen V. Tran, TomaszR. reflectionsin a real environment.A virtual audiodisplay, however, can be Letowski, and Kim S. Abouchacra (US Army Res. Lab., usedto examinethe effectsof early and late reflectionson distanceiden- AMSRL-HR-SD,Bldg. 520, Aberdeen Proving Ground, MD 21005-5425) tification.In this experiment,a virtual audio displaysimulates distant sound sourcesunder 4 conditions:Without reflections,with an early re- A seriesof experimentswas conductedto evaluate3D auditorybea- flection(floor reflection) only, with late reflections(reverberation) only, consto be usedby' drivers of remote-controlledvehicles. The auditory andwit h bothearly and late reflections. In eachtrial, the subjectsidentify beaconswere generated from an externalsound source, conditioned using the distanceof the simulatedsound source from one of 5 possibledis- the ConvolvotronTM and then presentedthrough Sennheiser HD-580 ear- tances:2, 4, 8, 16, and 32 ft. Numberedtargets are placedat the locations phones.In addition,a pink noisemasker was presented through an over- of the simulatedsound sources, allowing the subjectsto visualizethe headloudspeaker at a levelof 80 dBA measuredunder the earphones. Ten distancesinvolved. White noise and speechare used as stimuli in the listenerswith nrrmal hearing were asked to (1) judge sound quality of nine experiment,and their amplitudesare randomizedover 24 dB tb prevent identificationbased on intensityalone. The results will be'analyzedto auditorybeacons, and (2) movea beacon,from a predeterminedstarting measurethe percentageof correctresponses at eachdistance and the in- locationto a positiondirectly in frontof the listenerin the 3D display.The formation transfer in each of the 4 conditions. beaconsdiffered regarding type of soundas well as rateand mode (con- tinuousversus noncontinuous and singleversus oscillating sound source) 2aPP49. Measurement of localization ability using virtual audio cues presentation.Results of theexperiments indicate that listeners preferred (1) and visualtarget acquisition. WilliamR. D'Angelo (AL/CFBA,2610 continuousversus interrupted presentation of the beacons,(2) nonspeech SeventhSt., WPAFB, OH 45433-2901), RichardL. McKinley (AL/ versusspeech beacons, and (3) a rateof 1.1repetiti,o, nsper second over 0.7 CFBA, WPAFB, OH 45433), David R. Pertort (CaliforniaState Univ., or 2.5 repetitionsper second.Mode of presentationdid not affect the Los Angeles,CA), and Larry Hettinger (LogiconTechnical Services, overalllocalization accuracy or thenumber of frontversus back confusions Inc., WPAFB, OH 45433) madeby thelisteners. Results of theexperiments will assistin theselection Visualtarget detection was used to demonstratethe abilityof subjects of beaconsfor auditorydisplays used for operationof remote-controlled to localizewith a virtualaudio display. The testingfacility consistedof vehicles. audiopresented over headphones with andwithout localization cues and a 2aPP53. A cognitive perspective on audio delay tolerance in projectionscreen b?ring the visual scene. In eachtrial the visual target telecommunications.Larry Marturano (NorthwesternUniv., Evanston, appearedas onepixel at a randomlocation of the screen.The targetgrew IL 00208) in sizeuntil foundby the subject.The soundcue came on at thresholdlevel andbecame progressively louder until the target was found. The audiocue A set of tests are described in which the effects of echo-free audio waspink noisewhile the visualtargets consisted of aircrafticons. Subject reactiontime was measuredfrom targetonset to targetdetection. As indi- delay on PCM-encoded speech are evaluated. In these tests, a catedby the preliminary data, the localized audio conditiop faithfully pro- conversation-typesubjective speech assessment technique is used,which is vided the locationof the targetresulting in reactiontimes significantly augmentedwith several objective measures of conversationalperformance. better than with the nonlocalized audio cue. At the same time, a measureof mental workload is studiedto assessthe cognitiveeffects of audiodelay on the humanend user.The workload 2aPP50.Aurally aided visual searchunder static and moving measurethat is usedis a secondarytask involving short term, or working, conditions.Debra L. Fergusonand David R. Perrott(Dept. of Psychol., memory.In describingthese experiments, relevant background information CaliforniaState Univ., 5151 UniversityDr., LosAngeles, CA 90032) is providedon audiodelay, which illustrates the difficulties in measuring Auditorylocalization of staticand dynamictargets in the presenceor useracceptability of audiodelay. Information on humanmemory models absenceof an (broadbandnoise) auditory cue was examinedin a two- and.key experimental findings are reviewed, which motivate the choice of alternative,forced-choice paradigm. The locationof thetarget varied rela- workloadmeasure used in this study.The testmethodology and results are tive to the subject'sinitial fixationpoint. The right and left hemispheres thenreviewed in detail.User tolerance of audiodelay is foundto decrease were testedat 45, 90, and 135 deg azimuthon the zero degreeelevation withincreasing audio delay, in accordancewith other researchers findings. plane.Also testedwere zero and 180 deg locations.The rangeof target In addition,added cognitive load is demonstratedin the presenceof long velocitieswas 0, 10, 20, or 40 degper second,with directionof traveland delaysvia decreasedworking memory performance. velocityrandomized in eachtrial. Each main effect was significant as well 2aPP54. The relationship between tone frequency and perceived as two-way interactionsbetween conditionXlocationand condition elevationunder headphonelistening conditions. Alan D. Musicant xvelocity.These results suggest the utilizationof spatiallycorrelated au- (Dept.of Psychol.,Middle Tennessee St. Univ.,Box X063, Murfreesboro, ditorycues under static and moving conditions, particularly in theposterior TN 37132) fieldand at highervelocities. [Work supported by NSF.]
2aPP51. The role of auditory cues in assisting pursuit motor The relationshipbetween pure tone•frequency and perceivedin head functions. Renato G. Villacorte, David R. Perrott, and Debra L. elevationwas investigated. Stimuli were pure tones ranging from 1000to Ferguson (Psychoacoust.Lab., CaliforniaState Univ., Los Angeles,CA 1200Hz in 1000Hz steps.Insert earphones were utilized for presentation. 90032) Subjectswere instructed to indicate,on two separatediagrams, the image Eight experiencedsubjects were used in a two-alternative,forced- locationof thestimulus after presentation of a brieftone. Dimensions were choicevisual search paradigm in orderto investigatethe auditory system's left-right,front-back and elevation. All stimuliwere presented diotically, contributionin maintainingpursuit eye movementsafter the cue that in- thatis with equalintensity to thetwo ears.Tones were presented at ap- dicatedthe target's location, velocity, and direction of travelwas removed. proximately70 phonswith a variationof +-3dB. Perceivedin headloca- Subjectswere instructedto usethe targetmotion information provided by tion was found to vary systematicallyin the elevationdimension. Tones thecue to anticipatethe locationof the targetonset after the delay follow- withlower frequencies were perceived as lower in elevationthan tones of ing the cue's offset.Predictably, conditions that includedvisual target higherfrequency up to about9 kHz. Stimuliwith frequenciesof 10 kHz informationproduced faster RT's than a cue consistingof only auditory andhigher were perceived as lowerin elevationrelative to the perceived information.Performance also declinedwhen the velocity of the targetor elevation of the 8- and 9-kHz stimuli. Resultsof this experimentwere the durationof the delay was increased.These resultsmay suggestthe comparedto resultsfrom free fieldexperiments and found to be in general
3279 d. Acoust.Soc. Am., Vol. 97, No.5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3279
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp agreementwith thosereported by Butler[Conference on Binauraland ,?,aPP58,Interference with interaural time difference and intensity SpatialHearing, 1993]. Results of thisexperiment are compared with re- discrimination: Empirical and modeling study of efteels of sultsobtained in the moretypical iateralization paradigms. component level, spacing, and perceptual grouping. William S. Woods (Univ. Oldenburg, FB8/Mediziniscbe Physik, D-26111 2aPP$5. Perception of multiple echoes. Daniel D. McCall, Brian L. Oldenburg,Germany) Costantino,Rachel K. Clifton (Dept.of Psychol.,Univ. of Massachusetts, Amherst,MA01003), and RichardL. Freyman (Univ.of Massachusetts, The discrimination of the ITD of a 600-Hz tone was measured in the Arrdterst,MA 01003) presenceof othertones, with levelsof 75 and45 dB SPL/tone,spacings of 200 and400 Hz, andin thepresence of noisebands.Noiseband levels were SinceEbata et al. [J. Aeoust.Soc. Am. 44, 537-541 (1968)],little suchthat excitationpatterns with tonal and noiseinterferers were equalin experimentalor theoreticalwork hasbeen done on the perceptionof mul- a regionaround the target.Tonal interferers were presentedwith simulta- tiple echoes.In the current experiment,listeners seated in an anechoic neous onsets and offsets, 250-ms onset asynchrony,or continuously. chamberwere presentedwith 4-ms noisebursts in a lead-lag-lagconfigu- Noisebandswere presentedcontinuously. At the lowestpresentation level ration.The lead burstwas presentedfrom a loudspeakerat 45ø left of with the widestspacing and continuoustonal interferers,jnds showedno midlineand one lag burst(lag A) was presentedat midline.Listeners increaseover the target-alonejnd, i.e., no interference.Decreased spacing discriminatedthe locationof a secondlag burst(lag B) presentedfrom a or increasedlevel caused increasedjnds (i.e., interference).Lesser- loudspeakerat either 35ø or 55ø right of midline. Keepingthe delay be- experiencedsubjects showed more interferencein the asynchronous-onset twcenlead and lag B constant,a rangeof delaysbetween lead and lag A conditionthan in the continuous-tonecondition. Measurements of intensity was presentedto determinewhether changing the delayof lag A had an jnds in a subsetof conditions.yielded similar results. These results are effectupon the perceptionof lag B. Presentationof lag A interferedwith consistentwith interferencecaused by spreadof excitationand pulsing of the perceptionof lag B over a wide rangeof lag A delays,such that interferersbeing as significantas interferenceexpected from auditory subjects'discrimination of the locationof lag B was poorerwhen com- grouping.A filter-basedcross-correlation model for ITD processingis paredto the discriminationof lag B when lag A was absent.The data shownto be consistentwith pastand present ITD jnd results.[Work sup- suggestthat the introductionof an earlierecho serves to suppressdirec- portedby NIDCD (GrantDC00100).] tionalinformation from a subsequentecho. [Work supported by NIH grant DC01625.] 2aPP59. Binaural profile analysis: On the comparisonof interaural time differenceand interaural correlation acrossfrequency. William 2aPP56. Localization suppression and echo suppression aspects of S. Woods (Univ. Oldenburg, FBS/MediziniscbePhysik, D-26111 the precedenceeffect. XuefengYang and D. WesleyGrantham (Bill Oldenburg,Germany), Andrew R. Braghera,and H. StevenColburn WilkcrsonCtr. and Div. of Hear. and SpeechSci., VanderbiltUniv. School (BostonUniv., Boston,MA 02215) of Medicine, 1114 19th Ave. South,Nashville, TN 37212) Experimentsarereported on that we•.,aimed at determiningif a The precedenceeffect is a phenomenonthat may occurwhen a sound "profile-analysis"process is performedin the binauraldomain, specifi- fromone direction (the lead) is followedwithin a few millisecondsby the callywith interauraltime diiference (ITD) •nd interauralcorrelation (IC). sameor a similarsound from anotherdirection (the lag, or the echo). Sensitivityto variationsin theseparameters across frequency was investi- Typicallythe lag soundis not heardas a separateevent and the lag sound gatedby rovingthe parametersacross intervals and requesting subjects to cannotbe localized.Traditionally these two aspectsof precedence(echo choosethe intervalcontaining an incrementallydifferent parameter value suppressionand localization suppression) have been assumed to represent in a targetband. The size of the incrementneeded to identifythe target the operationof a singlemechanism. The hypothesisis proposedin this interval was measured for several bandwidths of the total stimulus. In the studythat localizationsuppression and echosuppression are at leastpar- ITD experiments,trne complexeswere usedand the targetwas a toneat tially independentphenomena. A seriesof experimentswas conductedto 500 Hz. For harmoniccomplexes (100-Hz spacing),the additionof refer- test this hypothesisas well as to investigatethe acousticparameters that encetones (out to 4 kHz) doesnot aid detectionof the targetinterval but affect the magnitudeof localizationsuppression and echo suppression.In usuallydegrades performance. For logarithmiccomplexes (spacing factor the firstexperiment subjects showed a significantlygreater degree of echo 1.3) performanceimproved at the widest(4 kHz) bandwidth.In the IC suppressionthan of localizationsuppression when presented with an ex- experiment,spectrally continuous noise was used,with a 115-Hz wide tendedtrain of lead-lag noise burst pairs. In other experimentsit was targetband at 500 Hz. Addingfringe bandsincreased thresholds signifi- shownthat the magnitudeof localizationsuppression is affectedprimarily cantlyfor a narrowstimulus bandwidth (354 Hz), and performancere- by the degreeof spectraloverlap of leadand lag sounds,and to a lesser turnedto that measuredfor the targetalone for wide bandwidths.These extentby the relative"localization strength" of the two sounds[P. L. resultsare discussed in termsof possiblebinaural contributions to auditory Divenyi,J. Acoust.Soe. Am. 91, 1078-1084(1992)]. [Work supported by grouping.[Work supported by NIDCD (GrantDC00100).] NIDCD.] 2aPP60. Interaural phase locking as a function of interaural level. 2aPP$7. The effect of background noise on the precedence effect. G. O. R. Green, A. Rees (Dept. of Physiol.Sci., The Medical School, Yuan-ChuanChiang and Richard L. Freyman (Dept. of Commun. Newcastle-upon-TyneNE2 4HH, UK), and G. B. Henning (Oxford Disorders,6 Arnold House, Univ. of Massachusetts,Amherst, MA 01003) Univ., Oxford OXl 3UD, UK)
The currentexperiment examined the influenceof noiseon the prece- Sinusoidalphase modulation in a sinusoidalcarrier was monaurally denceeffect, focusingon the importanceof noise sourcelocation. Listen- presentedto observers'left ears in standardtwo-interval forced-choice ers seatedin an anechoicchamber judged whether the imageproduced by experiments:The ca.t-tierwas phasemodulated in one of two randomly a lead-lagpair of 4-msnoise bursts (2-ms delay) was to the left or rightof chosenobservation intervals and the observerswere required to indicated midline.The lag loudspeakerwas fixed at 45 ø to the left or right, while the the intervalhaving phase modulation. In the dichoticcondition, a puretone lead loudspeakerwas positionedat a variable numberof degreesto the withthe same frequency (500 Hz) andlevel (70 dB SPL)as the carrier was oppositeside. The angleof the lead loudspeakerproducing 50% judge- presentedto the right ear in both observationintervals; in the monaural mentsfavoring the lead was used to estimateits perceptualweighting condition,the puretone was attenuatedby 71 dB. The 1.5-s stimuliwere relativeto the lag.This weighting,which was quantified using the c metric gated simultaneouslywith 20~msGaussian rise/fall times. At low modu- developedby Shinn-Cunninghamet al. [J..Acoust.Soc. Am. 93, 2923- lation rates,the depthof phasemodulation corresponding to 75% correct 2932 (1993)],strongly favored the lead when the sounds were presented in responsesin the dichoticcondition was an orderof magnitudesmaller than quiet.The valueof c wasreduced markedly when background broadband in the correspondingmonaural condition consistent with the resultsof G. noisewas introduced from 0 ø or 180ø angles,supporting previous findings G. R. Green,J. S. Heifer, and D. A. Ross[J. PhysioL(London) 260, of a weakenedprecedence effect in noise.When the backgroundnoise 49P-50P(1976)]. The dichotic advantage is scarcely affected by twoor- sourcewas off-midline,or lead-lagpairs of noisesources were used,the dersof magnitudereduction in the level of the puretone in the rightear. effectsof noiseon c werecomplex and asymmetric. [Work supported by The resultsare relatedto the precisionof phaselocking in the auditory NIH #DC01625.] system.[Work supported by theRoyal Society.]
3280 d. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of Amedca 3280
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 2aPP61. Across-frequency interaural pattern discrimination. 2aPP64. Masking and aging: II. Human behavioraland auditory JenniferJ. Lentz (Dept.of Bioeng.,Univ. of Pennsylvania,Philadelphia, brain-stemresponse thresholds. JudyR. Dubno,John H. Mills, Jayne PA 19103) and Virginia M. Richards (Univ. of Pennsylvania, B. Ahlstrom,and Lois J• Matthews (Dept. of Otolarygol.and Commun. Philadelphia,PA 19103) Sci., Medical Univ. of SouthCarolina, 171 AshleyAve., Charleston,SC 29425-2242) The ability of observersto detectchanges in interauralintensity dif- ference acrossfrequencies was testedusing multitonecomplexes. The Masked thresholdsmeasured psychophysically are equivalentfor tonalcomponents ranged in frequencyfrom 200 to 5000 Hz, with ampli- youngand agedhuman subjects with equalquiet thresholds. However, tudesrandomly drawn from a Gaussiandistribution having a meanof 60 highermasked thresholds derived from auditorybrain-stem responses dB SPLand a givenvariance. For thestandard stimulus, variance was zero, (ABR) are observedfor agedthan for younggerbils, independent of quiet providingequal-amplitude tones. The signalstimulus had a nonzerovari- thresholds.The purposeof thisexeriment was to characterizefurther age- ance.Because independently drawn signal stimuli were presented to the relatedchanges in maskingby comparingmasked thresholds measured left and right ears,interaural level differencesvaried randomly across electrophysiologicallyandpsychophysically for youngand aged humans frequency.Percent correct signal detections were measured as a functionof with normalhearing. Signals were Gaussian 1.8-ms tone pips at 1.0,2.0, the varianceof the signalstimulus. To encouragediscrimination based on and 4.0 kHz; the maskerwas a 1.0 kHz, low-pass-filterednoise. Using the patternof interaurallevel differences across frequency rather than the identicalsignals, ABR andbehavioral thresholds were measured in quiet and in maskers with overall levels of 74, 82, and 90 dB SPL. Thresholds changefrom diotic(standard) to dichotic(standard+signal), the overall levelsof thestimuli presented to eachear wereindependently chosen from measuredpsychophysically are equivalentfor youngand aged subjects in bothon- and off-frequencymasking conditions, consistent with previous a 7-dB range.Because standard and standard+signalpower spectra dif- fered, monauralcues to the presenceof the signalwere available.Thus findings.However, quiet and masked ABR thresholdsare higherfor aged than for young subjects,and maskingfunctions are shallower.Thus, psychometricfunctions were separatelyobtained using the samesignal whereasABR thresholdsof agedhumans are higherthan their behavioral stimulusat bothears. Results indicate that the detectabilityof changesin thresholds,they are consistentwith elevatedABR thresholdsobserved in interaurallevel differencesacross frequency is nearly the sameas the agedgerbils. More direct comparisons of thecharacteristics of human and detectabilityof changesin powerspectra for dioficpresentations. [Work gerbilABRs are contained in a companionposter. [Work supported by fundedby NIH.] NIDCD.] 2aPP62. Distortion product otoacousticemissions created through 2aPP65. Masking and aging: lII. Human and gerbil neural the interaction of a spontaneous otoacoustic emission and an input/outputfunctions. JohnH. Mills, Lois J. Matthews,Richard A. externally generated tone. Linda W. Norfix and TheodoreJ. Glattke Schmiedt,Flint A. Boettcher,Judy R. Dubno, and Jayne B. Ahlstrom (Dept.of Speech& Hear.Sci., Univ. of Arizona,Tucson; AZ 85721) (Dept. of Otolaryngol.and Commun.Sci., Medical Univ. of South Carolina,171 Ashley Ave., Charleston, SC 29425-2242) An SOAE(f2) andone XT (f0 wereused to create2 f•--f2 DPOAEs. Externaltones were appliedto the ear canalat SOAE/f• ratiosbetween To accountfor highermasked ABR thresholds,input-output (I/O) 1.08and 1.22 XT/SOAE intensitydifferences varied from 0 to approxi- functionsof theABR wereexamined. For bothaging humans and gerbils, mately50 dB SPL. DPOAE amplitudeand SOAE suppressioncharacter- amplitudesof theABR were smaller and slopes of ABRI/O functionswere isticswere variable across subjects. However, the followingtrends were lesssteep than those of youngsubjects. Smaller amplitudes could indicate noted:(1) At largerfrequency ratios, DPOAE generationand SOAE sup- abnormalfunction of the brainstemor an alteredinput to the brainstem pressionwere associated with greater XT SPLs;(2) DPOAEgrowth func- from the periphery.Analysis of I/O functionsof the compoundaction tions were characterizedby slopes<1 dB/dB, a maximum,rollover and potential(CAP) of the auditorynerve of aginggerbils also showeda disappearanceinto the noisefloor; (3) maximumDPOAEs were observed decreasein slope.Decreases in theslope of theCAP canbe attributedto a at frequenciesapproximately • oct below the SOAEs; (4) DPOAEmaxi- lossof 10%-30% of spiralganglion cells, to a reductionin synchronous mumswere associatedwith a significantamount of SOAE suppression. neuralactivity of the remainingnerve fibers, and to a reductionof the The resultsare consistent with DPOAEscreated using two low-leveltones endocochlearpotential. Thus, our hypothesis is thatthe unusual amounts of [Brownand Gaskill, in Mechanicsand Biophysicsof Hearing(Springer- maskingobserved in theABR of bothaging humans and gerbils can be Verlag,Berlin, 1990)] and can be interpretedby considering suppression in accountedfor by age-relatedalterations in theauditory periphery. It is also a nonlinearcochlear model [Zwicker, J. Acoust.Soc. Am. 80, 163-176 ourhypothesis that behavioral measurements of normal quiet and masked (1986).] [Work supportedby NIH-NIDCD grant I P60 DC-01409 and thresholdsin aginghumans do not necessarilyreflect an intactauditory Univ.of AZ GraduateStudent Development Fund.] periphery.[Work supported by NIDCD.] 2aPP63.Masking and aging:I. Gerbil auditorybrain-stem response 2aPP66. Neural encodingof level in the auditory nerve and thresholds. Flint A. Boettcher,John H. Mills, and Barbara N. Schmiedt anteroventral cochlear nucleus: A study of neural models and (Dept. of Otolaryngol.and Commun.Sci., Medical Univ. of South physiologicalresponses. M.A. Burockand L. H. Carney (Dept.of Carolina,171 Ashley Ave., Charleston, SC 29425-2242) Biomed.Eng., 44 CummingtonSt., Boston Univ., Boston, MA 02215)
Masked thresholdsestimated from auditory brain-stem responses Models for level discriminationbased on neuralcounts require "pool- (ABR)of aginggerbils are 20-30 dB higherthan the masked thresholds of ing" of auditory-nerve(AN) fiber responsesto explainhuman perfor- younggerbils when quiet thresholds are equal. In thispresentation, we will mance.Neither the mechanismnor siteof this "pooling"is known.This discussdata on young (6 month)gerbils with normal hearing and aged (36 studyconcerns the transformationof AN responsesin the anteroventral month)gerbils with a rangeof hearinglevels. ABR thresholdswere mea- cochlearnucleus (AVCN). An AN modelwith statisticsconsistent with suredat 1, 2, 4, 8, and 16 kHz in quietand in the presenceof a low-pass physiologicaldata [mean-to-variance ratio (a)•2] providedinputs to filterednoise (1 kHz upperbound) at levelsof 50, 60, and 70 dB SPL. coincidence-detectingmodels for AVCN cells. The a of coincidence- Youngsubjects had linear growth of maskingof signalswithin the pass- detectingcell models is lowerthan the a of AN fibers.Responses of most bandof the noise.At higherfrequencies, only minimalmasking was ob- gerbilAVCN neurons to (frozen)wideband noise had oe less than 2, con- served.In contrast,aged subjects showed much higher masked thresholds sistentwith a coincidence-detectionmechanism. The lower a impliesthese at 2 and 4 kHz comparedto young subjcct•.This occurredfor both aged cells would not be as effective a• AN fibers for encoding level in term• of subjectswith minimal age-related threshold elevation and those with large rate.To optimally"pool" these responses would require either summation hearinglosses. In accordancewith previousstudies, masked ABR thresh- of a greaternumber of elements,or steeperrate-level curves (to compen- oldsin aginggerbils are muchhigher than those in younggerbils. This satefor lower a) and thusmore elements to spana wide dynamicrange. phenomenonis examined in humansubjects with behavioraland ABR Neuralcoincidence detection may contribute to processingspectral infor- techniquesin the companion presentations. [Work supported byNIDCD.] mation(monaurally) and localizationinformation (binaurally). This
3281 d.Acoust. Sec. Am., Vol. 97, No.5, Pt.2, May1995 129thMeeting: Acoustical Society of America 3281
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp mechanismdoes not providean advantage,and perhapsintroduces a dis- 2aPP69. Rate of rise sensitivity.of medial geniculateneurons in the advantage,for processingintensity information in the form of discharge squirrel monkey. John F. Olsen (Lab. Neurophysio!.,NIMH, NIH, rate.[Work supported by NIH, WhitakerFoundation.] Bldg. 110,P.O. Box 608, Poolesville,MD 20837) 2aPP67.Responses of cochlear nucleus units in thechinchilla tobest frequencytones amplitude modulated by low-frequency,two-tone In this studyneural sensitivity to rate of rise was measured.The re- complexes.W.P. Shofner,S. Sheft,and S. Guzman (ParmlyHear. Inst., sponsesof 32 medialgeniculate neurons to linearincrements of a broad- LoyolaUniv. Chicago, 6525 N. SheridanRd., Chicago,IL 60626) band noise from a definedbaseline level were recordedextracellularly. Steprise time (3-96 ms), stepamplitude (6-24 dB}, and baselinelevel A tonethat is amplitudemodulated by two tones(froot, and freon2) containsno spectralenergy at the envelopebeat frequency (fmod2--fmodl) (0-73 dB SPL) werevaried independently. A typicalresponse to the step for either the stimulus waveform or the half-wave rectified waveform. consistedof a transientburst of 1-8 spikes.Response probability in- Preliminarydata showedthat Fourieranalysis of post-stimulustime his- creasedas a functionof the step'srate of rise (amplitude/risetime), such togramsof chinchillaCN unitsrecorded in responseto BF tonesthat were thatincreases in risetime couldbe tradedfor proportionalincreases in step amplitudemodulated by two tonesOrmoaJ, fm•2<64 I-[z) yieldsspectral amplitudeto obtain a criterionresponse. Increases in baselinelevel de- peaksatf, noa•-fmoa• in additionto thepeaks at fmoa• and freon2 [Shofner creasedthe slope of the probabilityversus rate of me functionand in- and Sheft,J. Acoust.Soc. Am. 93, 2410(A) (1993)].The magnitudesof creasedthe thresholdrate of rise.Response probability was independent of thesespectral peaks are measuresof synchronyat eachfrequency compo- peaklevel (=baselinelevel+step amplitude). The resultsshow that the nent.For all units,synchrony at f,,od• andfreon2 is greaterthan the syn- responseof a commontype of roedialgeniculate neuron is determinedby chronyat fmo•-fmoa•. For a given unit, synchronyat fmo•Jand frr• the rate at which stimulusamplitude increases from a definedbackground remainsrelatively constant as a functionof overall level, whereassyn- level, indicatinga possiblerole for theseneurons in the perceptualsegre- chronyat fmoa•_-fmod2 decreases as the level increases. Synchrony at fmoa• gationof auditoryevents [A. S. Bregman,P. A. Ahad, and I. Kim, I. andfm• is largestin chopperunits, intermediate in primarylikeunits, and Acoust.Soc. Am. 96, 2694-2703 (1994)]. smallestin onsetunits. This hierarchydiffers from that describedin the literaturefor CN unitsin responseto BF tonesmodulated at bestmodu- 2aPP70. Neural processesof auditory scene analysis observed by lation frequencies.No hierarchyappears to exist for synchronyat magnetencephalography.S. lmaizumi,K. Mori, S. Kiritani (Res.Inst. fmoa2-fmoa•.[Work supported by a PPGfrom NIDCD.] of Logopedicsand Phoniatrics, Faculty of Medicine,Univ. of Tokyo,7-3-I 2aPP68. A comparisonof the efficiency and accuracy of medial Hongo, Bunkyo-ku,Tokyo, 113 Japan},and M. Yumoto (Univ. of superiorolive cell simulations. TrevorM. Shackleton(Dept. of Exp. Tokyo,7-3-1 Hongo,Bunkyo-ku, Tokyo, 113 Japan) Psychol.,Univ. of Sussex,Brighton, E. SussexBNI 9QG, UK) Binauralprocessing of interauraltime differences(ITDs) is widely Auditory-evokedmagnetic field elicited by three soundstimuli con- believedto be performedby a cross-correlationmechanism. Cells have sistingof a spokenword, a click, and their overlappingversion, was mea- been found in the roedial-superiorolive (MSO) and inferior colliculus suredusing BTi 37ch SQUID MEG systemfrom the contralateral hemi- which respondmost strongly when presentedwith stimuli with a charac- sphere of the stimulatedears of seven normal heating subjects.Three teristicITD (EE cells).These cells are believedto form the basisfor such stimuli were presentedin a random order with a random interstimulus a mechanism.In this study we comparethe performanceof cells basedon intervalbetween 1 and2 s at the mostcomfortable hearing level. Two tasks simplecross-correlation, coincidence detector cells basedon a novel de- were imposed:One is to count the click, and the other is to count the terministic method, and coincidencedetectors based on Monte-Carlo simu- spokenword. Significantdifferences in the responsewere observedbe- lation. The deterministicmodel is based upon the requirementthat the tweenthe tasks.For both the tasks,a neuralactivity in the left and right probabilityof a givennumber of inputsfrom the auditorynerves of either earmust exceed a thresholdamount within' a finitetime (coincidence temporalauditory cortices was observed for all thestimuli. When counting window)before the moo'Icier cell'can fire. W• examinethe firing rate and the click, a wide spreadactivity was elicitedby the overlappingclick vector strengthas a functionof ITD, overall level, and interaurallevel suggestingpossible contribution of a frontal neuralactivity in the right differenceOLD) andconapare our resultswith the datafrom cellsin the hemisphere.The resultssuggest that plural neural mechanisms may con- MSO. We find that a simplecross correlation cell is inadequateto describe cem the auditoryscene analysis by which the overlappingsound objects the data. However, the deterministiccell and Monte-Carlo simulation,both are distinctivelyperceived. The temporal-lobeactivity may reflectauto- with a coincidencewindow width of 0.2 ms, describethe data very well. maticmemory trace construction, and the frontal-lobeactivity may con- [Worksupported by The WellcomeTrust, UK.] ceru attentionalselection of a memorytrace.
3282 J. Acoust.Soc. Am., VoL97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3282
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp WEDNESDAY MORNING, 31 MAY 1995 MEETING ROOMS 12, 13, 14, 8:30 TO 11:30 A.M.
Session 2aSA
StructuralAcoustics and Vibration:Scattering
HansonHunrig, Chair NavalSurface Warfare Center, Indian Head Division, White Oak, Silver 3•ring, Maryland 20903-5640
ContributedPapers
8:30 9:00
2aSAI. Phase-spaeeprocessing of scatteringfrom a submerged 2aSA3. The exact sonar crosssection of an elasticspherical shell elasticlayer. RaymondJ. Nagera,Leopold B. Felsen,and Brian 1. near the seasurface. H. Huang (NavalSurface Warfare Center, Indian Collins {Dept. of Aerospaceand Mech. Eng.. BostonUniv., I I0 HeadDiv., SilverSpring, MD 20903-5640)and G.C. Gaunaurd(Naval CummingtonSt., Boston,MA 02215) SurfaceWarfare Ctr., CardcrockDiv., WhiteOak, SilverSpring, MD 20903-5640) In scatteringfrom an insonifiedsubmerged elastic layer, whose surface isperturbed with periodic or quasiperiodicvariations, the resulting Bragg The acousticscattering hy a submergedspherical elastic shell near a modesare expected to coupleto theleaky modes that can be radiatedby freesurface and insonificd by planewaves at arbitraryangles of incidence theunperturbed smooth layer. If thesetwo distinct but coupled phenom- is analyzedin an exactfashion by the classicalseparation of variables enologiescan be separalelyidentified and extracted from acousticscatter- method.To satisfythe boundaryconditions at the free seasurface, as well ingdata by "wave-oriented"processing, one may gain discriminants for ason thesurfaces of theelastic shell, the mathematical problem is formu- imagingthe properties of theelastic layer and of its surfacetopology. A latedusing the method of images.The scattered wave fields are expanded simpletwo dimensional model--a finite array of filamentaryscatterers on in termsof sphericalwave functions using the additiontheorems. The final the insonifiedface of a fluidlayer--has been investigated previously IT. resultscome out in termsof Wigher 3-j symbolsor Clebsch-Gordan Hsu, L. B. Felsen,and L. Carin, to appearin IEEE Trans.Antennas coefficients.Quite similar to the problem of scatteringby multiplespheres, Propag.].It hasbeen shown that windowed-transform processing of data the computationof the scatteredpressure field involvesthe solutionof an ob•rved alonga trackparallel to the layerextracts space-wave-number i[[-couditionedcomplex matrix system, of sizethat depends on thenumber phasespace distributions in which the leaky mode and Bragg mode foot- of termsin the modalseries required for convergence.This, in turn,de- prinlsare clearly separated; these features are poorly resolved in theun- pendson the value of thefrequency and on the proximity of thesteel shell processeddata. The present paper explores these phenomenologies and the to the free surface.The matrixequation is solvedby the Gauss-Seidel correspondingphase-space processing when the fluidlayer is replacedby method.Many backscatteredechoes from the shellare computed, and its an elasticlayer with its far richervariety of layer-guidedmodes. Paramet- form functionis displayedfor variousdepths and in broadfrequency in- ricstudies show how the space-wave-number distributions are affected by tervals.The plotsshow that the large-amplitude, low-frequency resonance theprocessing window size, the physical parameters of thelayer, and the featuresin thesonar cross-sections shift upward as the shell approaches the sizeand spacingof the filamentarray. free surface. This can be attributed to the decrease of added mass for the shellvibration. [Work partially supported by the IndependentResearch Programof the CDNSWC.]
9:15 8:45 2aSA4. A theory for predicting the scattered signals from elastic 2aSA2. Variable phasecoupling coefficient for leaky wavesfrom spheroidalshells near smooth absorbing interfaces. M. F. Werby resonancescattering theory and physical aspects of background {Naval Res. Lab., Stennis Space Center, MS 39529) and N.A. contributions. Philip L. Marston (Dept. of Phys.,Washington State Sidorovskaia(Univ. of New Orleans,New Orleans,LA 70148) Univ., Pullman,WA 99164-2814) A new formulation that allows one to describe backscattered echoes Approximationsare examinedfor the couplingcoefficient Gt for the from elasticshells near absorbing plane interfaces is presented.This for- launchingand detachment of leakywaves having application to situations mulationis alwaysconsistent even at low frequenciesand large distances wherethin shell theoryis not applicable.The approachis basedon a from the interfacesand allows the rapid reproductionof backscattered comparisonof ray and resonancescattering theory (RST) formulations echoesover frequencyranges of practicalinterest. This novel formulation whichincludes effects on thephase of Gt of higher-orderDehye approxi- is developedand is shownto be consistentwith thatreflecting interfaces. mationsof Hankelfunctions and derivatives [P. L. Marston,Wave Motion The methodhas been implementedand numericalresults for both pulse (acceptedfor publication)].The comparison includes a frequencydepen- andcontinuous wave signals are carried out. [Work sponsored byNRL and denttransition (between soft and rigid limits)for the RST background the Officeof NavalResearch.] factorin the productexpansion of the S function.The transitionis formu- latedsuch as to not affect IGtl. The high frequency phase of Gt forlimiling backgroundcases previously examined [P. L. Marstonand K. L. Williams, 9:30 J. Acoust.Soc. Am. Suppl.I 83, S94 {1988)] S94 (1988)] is recovered.A 2aSA5, Animations of pulse signals scattering from submerged variablephase term depending on the backgroundtransition function cor- resonatingstructures, M. E Werby (NavalRes. Lab., StennisSpace respondsto a term given by the convolulion formulation of variable cur- Center,MS 39529) and N.A. Sidorovskaia(Univ. of New Orleans,New vaturescattering [P. L. Marston,I. Acoust.Soc. Am. 97, 34-41 (1995)] Orleans,LA 70148) when applied to thin circular cylindrical shells. Other correlationswith shelltheory are evident. Diffractire and inertial aspects of thebackground A formulationthat allows one to describescattering from objects in a contributionare alsoexamined. [Work supported by the Officeof Naval waveguidehas beendeveloped. The methodis basedon couplingthe Research.[ free-fieldT-matrix to a waveguideusing the normalmode code SWAMP
3283 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3283
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp andthe T-matrixcodes developed at NRL. Thisformulation allows for the intothe medium.The needto accountfor it hasclassically prompted the rapidreproduction of solutionsand allows one to replicatepulse scattering developmentof a new mathematicalinterpretation of scattering,called from resonatingobjects in a waveguide.Animations of signalsscattering "unsteadyaerodynamics," so that flow and flowlessdiffraction communi- from resonatingobjects is presented.The resultsare shownto enhance tieshave tended to work in mutualisolation. A sideobjective of thispaper insightinto the physicsof suchscattering processes. is to speakto both groupsby presentinga completelyformal complex- contourrepresentation of the fundamentallift kernelfor the flowcase. That spectralformulation displays the role of vorticity explicitly throughan 9:45 additionalsingularity that shiftsaway to complexinfinity as the flow is turnedoff. The remainingspecU-um is the Fourier transformof the hyper- 2aSA6. Elastic scattering of a spherical acousticwave by an infinite singulardiffraction kernel of ordinaryacoustics. fluid-filled cylindrical shell. StirlingS. Dodd and CharlesM. Loeffier (AdvancedSonar Group, Appl. Res. Lab., Univ. of Texasat Austin,P.O. Box 8029, Austin,TX 78713-8029) 10:45 A methodof describingspherical acoustic waves in cylindricalcoor- 2aSA9. Generalized holography for imaging elastic structures. dinatesis appliedto the problemof pointsource scattering by an elastic RobertP. Porter, Daniel Rouseff (Appl.Phys. Lab., Univ. of Washington, infinitefluid-filled cylindrical shell. L6on et el. developedthe scattering Seattle,WA 98105),and David Bennink (Appl.Measurement Systems, matrixfor plane-wavescattering by an infinitehollow cylindricalshell Bremerton,WA) [L6onet el., $. Acoust.Soc. Am. 91, 1388-1397(1992)]. By usinga methodof expressinga sphericalwave in cylindricalcoordinates in a form Generalizedholography is a techniquefor determiningthe properties similarto thatof a planewave in cylindricalcoordinates ILl andM. Ueda, of acousticalsources or scatterersJR. P. Porter,Progress in Optics27, J. Acoust.Soc. Am. 87, 1871-1879 (1990)], the resultof Leon et al. is 1989]. In its mostgeneral form, the radiatingor scatteredfield and its manipulatedinto an exactsolution for the sphericalwave, fluid-filled scat- normal derivativeare measuredon a recordingsurface of arbitrary shape. tering problem.The exact solutionis in an integral form that is treated The resultingmeasurements can be forwardpropagated into the far field to numerically.It is appliedto distributedsource and receiverarrays by treat- calculatethe radiationpattern. The field can also be backpropagatedto- ing them as setsof point sourcesand point receiversand then integrating wardthe originalsource location to generatean image.For the specialcase over their spatialextent. of a closedrecording surface surrounding the source,the imageis inde- pendentof the shapeof the hologram.Moreover, the imagewill be inde- 10:00-10:15 Break pendentof evanescent(subsonic) components of the field even when the measurementsare madein the near field. This is an importantconsider- ationfor locatingsources of radiationon an object.In this talk, generalized 10:15 holographyis appliedto simpleelastic structures to determinethe modes of vibration.Numerical results will be presentedfor sphericalshells ex- 2aSA7. Scattering from a fluid-loaded cylindrical shell with axially cited by localizedsurface pressure or by an incidentpressure wave. periodic circumferential constraints using analytical numerical matching. RickardC. Loftmanand Donald B. Bliss (Mech.Eng. and Mater. Sci., Duke Univ., Box 90300, Durham, NC 27708) 11:00
Acousticscattering from an infinitelylong, thin elasticcylindrical shell 2aSA10.Acoustical scattering by a penetrablewedge. AnthonyM. J. with axiallyperiodic circumferential constraints leads to the excitationof Davis (Dept.of Math.,Univ. of Alabama,Tuacaloosa, AL 35487-0350) flexural,longitudinal, and shearwaves on the shell. Of interestis the interaction of these structural waves with the discontinuous constraints, Considerthe two-dimensionalscattering of a time-harmonicsound and the effect of this interaction on the resultant scattered sound field. This wavegenerated by a line sourceand incidentupon a penetrablewedge. three-dimensional,fully coupled,structural acoustic problem is solved The wave speedsin the interiorand exteriorof the wedgeare distinctand with the aid of a new method called analytical/numericalmatching the radiationcondition of only outgoingwaves at infinity is appliedin all (ANM). The methodcombines high-resolution local analyticalsolutions directions.At the boundaryof the wedgethere is a pair of transmission and low-resolutionglobal numericalsolutions to more efficientlymodel conditionswhich ensurecontinuity of the acousticpressure and normal structuraldiscontinuities. ANM local solutionshave been developedto velocity.By usingsuitably modified Green's functions and considering efficientlycapture the rapid variationin systemresponse across the dis- separatelythe symmetric and antisymmetric parts of thepressure field with continuous constraint. The local solutions are combined with a smooth respectto the centerplane of the wedge,a pair of disjointintegral equa- global solution,modeled by modal methods,to form an accurate,uni- tions of the first kind can be obtainedfor the two partsof the normal formly valid compositesolution. The ANM compositesolution is more velocityon just oneface of the wedge.Transformation to equationsof the accurateand converges more rapidly than the traditionalmodal approach. secondkind is then achievedby usinga techniquefor solvingintegral An importantobservation is that this scatteringproblem exhibits consid- equationswith Henkel function kernels [D. Porter,IMA, ]. Appl.Math. 33, erablesensitivity to modelingaccuracy and convergenceof structuralre- 211-228 (1983)].The newkernels are houndedbut defined on the interval sponsein the regionof the discontinuities.Errors in theseregions have an (0, •). A numericalsolution must describe the far fieldwhich, at thewedge overall effect on the structureand the associatedscattered field. [Work boundary,will exhibitsome mixture of the two wave speeds. supportedby ONR.]
11:15 10:30 2aSAll, Acousticand flexural wave scatteringfrom a three member 2aSA8. Diffraction analyseswith and without flow: A unifying junction. DouglasA. Rebinskyand Andrew N. Norris (Dept.of Mech. spectralapproach. R. Martinez (CambridgeAcoust. Assoc., Inc., 200 andAerospace Eng., Rutgers Univ., Piscataway, NJ 08855-0909) BostonAve., Ste. 2500, Medford, MA 02155) A threemember junction is formedby a pair of semi-infiniteplates in This paper discussessample diffraction problems from the fields of contact with fluid on one side and a mechanical structure on the other. The structuralacoustics in a still mediumand of aeroacousticsat high subsonic latteris describedby an impedancematrix and the plates ave modeled by Mach numbers.Respectively and specifically:Diffraction by a tandem the classicaltheory of flexure.The scatteringproblem for obliqueinci- arrangementof thin circular platesof finite radiusand inertia, and scatter- denceis solvedusing the impedancemalxix for the platejunction without ing of high-frequencyrotor/stator noise by the nacelle of a modern the attachment.This is accomplishedusing the Wiener-Hopf technique to seroengine.The presenceof a freestreamendows the elementaldiffraction solvethe dualintegral equations for the unknownpressure on the plates. loadsin the secondclass of problemswith the capacityto injectvorticity Explicitformulae are obtained for thepressure transform, and correspond-
3284 J. Acoust.Soc. Am., Vol. 97, No.5, Pt.2, May1995 129thMeeting: Acoustical Society of America 3284
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp ing explicit and relatively simple expressionsare given for the various to frequencyand angle of incidenceincluding the effectof variouscritical diffraction coefficients associated with the fluid/structure interaction. Nu- angles.It is verifiedthat the generalsolution reduces to that for a pair of mericalresults fo• theredistribution of energyfrom flexural to flexuralplus plateswith clampedand welded junction conditions as limiting cases when acousticat a thicknessdiscontinuity will be discussedin detailwith respect the frameimpedance is zeroand infinite. [Work supported by ONR.]
WEDNESDAY MORNING, 31 MAY 1995 GRAND BALLROOM SOUTH, 7:45 TO 11:45 P.M.
Session 2aSC
SpeechCommunication: Bi-modal Speech Perception (Poster Session)
StephenA. Zahorian,Chair Electricaland ComputerEngineering Department, OM DominionUniversity, Norfolk, Virginia23529
ContributedPapers
All posterswill be on displayfrom 7:45 to I 1:45a.m. To allow contributorsan oppoflunityto seeother posters, contributors of odd-numberedpapers will be at theirposters from 7:45 to 9:45 a.m. andcontributors of even-numberedpapers will be at their posters from 9:45 to I 1:45 a.m.
2aSC1. Effectsof modalily on subjectiveestimates of frequencyand showedthat F0 supplementationsignificantly enhanced the visualpercep- recencyof spokenand printed words. DanielE. Gaygenand PaulA. tion of bothsegments and word and phrase boundaries, and interacted with Luce (LanguagePerception Lab.. Dept. of Psychology,University at context. [Work supportedby NIH Program Project Grant Buffalo, Buffalo. NY 14260) #5PO5DC00178.] Previousresearch (Pisoni and Garber,1990; Gatbet and Pisoni,i 991) hasdemonstrated that subjectivefamiliarity judgments for wordsare not 2aSC3. Age-related differences in performance measures for a differentiallyaffected by the modaltry(visual or auditory)in whichthe cross-modal auditory Stroop task. John W. Hawks, Anthony I. words are presented,suggesting that subjectsbase their judgmentson Caruso,and Wojtek W. Chodzko-Zajko (Schoolof SpeechPathel. and fairlyabstract, modality-independent representations in memory. However, Audiel., Kent StateUniv., Kent, OH 44242) in a recentlarge scale study in lapanese(Amano et aL, in press),markedly modalityeffects on familiarityratings were observed. The currentresearch Physiologicand taskperformance measures are comparedfor young furtherexamines possible modality differences in subjectiveratings and andelderly subjects on a simplespeeded task, an auditoryStroop task and their implicationsfor word recognition.Specially selecledwords were presentedto subjectsfor frequencyand recencyjudgments. In particular, a cross-modalauditoryvisual Stroop task usingverbal responses.The re- subjectswere askedhow frequently(or recently}they READ, WROTE, sultssuggested that all threetasks are perceivedas physiologicallystress- HEARD, or SAID a givenspoken or printedword. These ratings were then ful by bothsubject groups and that oldersubjects were more physiologi- usedto predictaccuracy and processing times in auditoryand visuallexical cally reactiveto visual stimuli than youngersubjects. Differences in decisionand namingtasks. Our resultssuggest modaltry dependence for reactiontimes suggested a longeroverall processingtime for older sub- somelexical representations, primarily for wordsthat occur fairly rarelyin jects, as well as greaterinterference in processingincongment stimuli. the language.[Work supported by NIDCD.] However,analysis of responseerrors indicated significantly better accu- 2aSC2. Speechreading with and without auditory F0 racy on difficult tasks for the older subjects.The implicationsof these supplementation:Effects of lexical and sententialcontext, Robin S. findingswill be discussedin termsof task strategicdifferences and re- Weldsteinand Arthur Boothroyd (Ctr. for Res.in Speechand Hear. Sci., source conservation. GraduateSchool and Univ. Center,City Universityof New York, 33 W. 42 St., New York. NY 10036) 2aSC4. The role of visual information in speaker normalization of This studyexamined the effectsof lexical and sententialcontext on fricatives. ElizabethA.Strand (Dept.of Linguist.,Ohio State lJniv., 222 speechreadingwith andwithout supplementation by an auditoryindicator OxleyHall, 1712Nell Ave.,Columbus, OH 43210-1298) of voicefundamental frequency (F0) in 12 adultswith normalhearing. Lexical contexteffects were assessedby measuringphonetic segment and This studyexamines the roleof visualinformation in speakernormal- syllablerecognition in CVC wordsand nonwords.Senlential context ef- izationof fricativesby comparinglisteners' responses to auditorystimuli feelswere assessed by measuringword recognition in normalsentences, in onlywith responses to audiovisual{McGurk-type) stimuli to determinethe syntacticallycorrect but semanticallyanomalous sentences. and in isola- effect that visual cues have in speakernormalization. Voices judged by tion (i.e.. no context).For the lexicalcontexts, improved performance was listenersas auditorilyambiguous and unambiguous with respectto gender seenby both speechreadingplus F0 and speechreadingalone in CVC wereused to constructfour continuaof tokensfrom/sad/ "sod" to wordsrelative to CVC nonwords.F0 supplementationcontributed to im- "shod"; the continuawere synchronizedwith videosof visually unam- provedconsonant recognition, presumably due to theprovision of cuesto biguouamale analfemale faeeggayin s the gamewordg. The audiovigual voicingpresence or absence.For the sentencecontexts. F0 supplementa- tion resultedin bestrecognition of wordsin normalsentences. while rec- stimuli, as well as the auditorysignals only. were then presentedto listen- ognitionof wordsin anomaloussentences was comparableto that for ers for identificationas either "sod" or "shod."Preliminary results suggest wordsin isolation.By contrast,results by speechreadingalone revealed that visuallydisambiguating information affects the perceptionof audito- similarrecognition of wordsin normalsentences and wordsin isolation. rily ambiguousvoices. This paperwill presentthe resultsof additional and poorerrecognition of words in anomaloussentences. The study testson a largerpool of listeners.[Work supported by NIH.]
3285 d. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3285
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 2aSC5. Effects of listener expectation on eye movement behavior 2aSC7. The McGurk effect in infants. Jennifer A. Johnson, Lawrence during audiovisualperception. lnge-MarieEigsti (ATR Human D. Rosenblum (Dept. of Psychol.,Univ. of California,Riverside. InformationProcessing Labs, 2-2 Hikaridai,Seika-cho, Soraku-gun, Kyoto Riverside,CA 92521), and Mark A. Schmuckler (Univ. of Toronto, 619-02,Japan), Eric Vatikiotis-Bateson,Sumio Yano, and Kevin G. ScarboroughCampus, Toronto, Canada) Munhall (QueensUniv., Canada) In previouswork [Vatikiotis-Batesonet al., Proc.ICSLP-94 2, 527- In the McGurk effect, auditoryspeech syllables are influencedby si- 530 (1994)],listener eye movementswere examined during audiovisual multaneouspresentation of discrcpantvisible speech syllables [McGurk perception.Clear effectsof maskingnoise level were observedin the andMcDonald, Nature 264, 746-748 (1976)].The effectis knownto be stabilityand location of the listener'sgaze. At highernoise levels, listeners strongerfor native English than native Japanese-speakingsubjects fixatedprimarily on the mouthand very little on the eyes.Listeners were [Sekiyamaand Tokhura, J. Acoust.Soc. Am. 90 (1991)]. It is unknown implicitlydirected to focuson phoneticdetail in the stimuli,by meansof whether the strengthof the effect is somethinglost or gained through questionsused to determineintelligibility of the stimulus;however, atten- developmentalexposure to a given language.To explorethis issue,two tion to phoneticdetail is only part of what goeson duringaudiovisual experimentstested for the MeGarkeffect in 5-month-oldEnglish-exposed communication.In the currentstudy, different patterns of eye movement infants.Infants were first gaze-habituated to an audiovisual/va/.They were were elicitedfrom 10 Englishlisteners by biasingthe listener'sfocus of thenpresented three different audiovisual combinations: audio/va/-visual attention.Two listenerbiases were tested---onetoward phonetic discrimi- /va/; audio/ba/-visual/va/(perceivedby adultsas/va/); andaudio Ida/- nations,as previouslystudied, and the othertoward practic information, e.g., havingto do with perceivedcharacteristics of the speaker.If visual visual /va/ (perceivedby adultsas Ida/). The infantshabituated to the cuesduring audiovisual pemeption are only partly phonetic,then differ- tokenswith audio/ha/and/va/componentsat the samerate, but habituated encesin the listener'sinterpretation of the experimentalgoals may evince moreslowly to the tokenwith audioIda/. Furthertests with a neutralstatic differentpatterns of eyemovement. For example, the perceived goal of the face and changingauditory syllables revealed that thesehabituation dif- experimentmay affect the relative proportion of gazefixations on theeyes ferenceswere not due to the auditorysimilarity of/ba/to/va/relative to and the mouth. Ida/. This suggeststhat the infantswere visuallyinfluenced in the same way as English-speakingadults. 2aSC6. The effect of face and lip inversion on audiovisual speech integration. DeborahA. Yakel, LawrenceD. Rosenblum (Dept. of 2aSC8. Auditory localizationand audiovisualspeech perception. J. Psychol.,Univ. of California,Riverside, Riverside, CA 92521), Kerry A. Jonesand K. G. Manhall (Dept.of Psychol.,Queen's Univ., Kingston, R Green (Univ. of Arizona), Chantel L. Bosley, and RebeccaA. ON KYL 3N6, Canada) Vasquez (Univ.of California,Riverside, Riverside, CA 92521)
Seeinga speakingface can influenceobservers' auditory perception of The influenceof the spatialposition of the acousfcsignal in audiovi- syllables[McGurk and McDonald, Nature 264, 746-748 (1976)].This sual speechperception was investigatedin a seriesof experimentsusing effectdecreases when the speaker's face is inverted]e.g., Green, J. Acoust. the McGurk effect. Subjectsviewed video disk recordingsof faces pro- Soc.Am. 95, 3014(1994)]. Face recognition is alsoinhibited with inverted ducingvisual VCV nonsensesyllables while simultaneousacoustic VCV faces]e.g., Rock, Sci. Am. 230, 78-85 (1974)] suggestinga similar un- stimuli were presentedfrom one of 7 different speakerslocations. The derlyingprocess. To furtherexplore the link betweenface and audiovisual speakerswere positioned in a semicirculararray in frontof the subject.in speechperception, a speechexperiment was designed to replicateanother separatestudies subjects were required to namethe intervocalicconsonant, faceperception effect. In this effect,an invertedface and an invertedface indicatethe locationof the soundsource using a computerizedpentiometer containingupright lips are perceived as looking normal, but an uprightface system,or performboth tasks. Preliminary results suggest that the subjects' with invertedlips looksgrotesque [Thompson, Perception 9, 438-484 (1980)].An audiovisualspeech experiment tested four pres•ntation condi- ability to localizethe positionof the auditorystimulus was influencedby the presenceof a visual stimulus.Specifically, subjects tended to localize tions:Upright face-uprightmouth, upright face-inverted mouth, inverted face-invertedmouth, inverted face-upright mouth. Various discrepent au- the soundcloser to the positionof the monitorshowing the visualstimulus. diovisualsyllables were testedin each condition.Visual influencesoc- However the strengthof the McGurk effect was not influencedby the curredin all but the uprightface-inverted mouth condition for someof the spatialposition of the soundsource. Subjects perceived the visual/g/and syllablecombinations thereby mimicking the face perceptioneffect. How- the auditory/b/combinationas/d/equally oftenat all soundlocations. The ever, other syllable combinationsrevealed visual influencesin all four independenceof the ventriloquisteffect and audiovisualintegration in the conditions.Results are interpretedin termsof articulatorydynamics and perceptionof the MeGark effect will be discussedin termsof spatial the verticalsymmetry of the visualstimuli. constraintson the cross-modalperception of speech.
3286 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3286
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp WEDNESDAY MORNING, 31 MAY 1995 MEETING ROOMS 10, 11, 8:25 A.M. TO 12:00 NOON
Session 2aSP
SignalProcessing in Acoustics:Wavelet Analysis Techniques and ApplicationsI
RandyL. Smith,Chair AppliedResearch Laboratories, University of Texasat Austin,P.O. Box 8029, Austin, Texas 78713-8029
Chair's Introduction4:25
Invited Papers
8:30
2aSP1.Overview of waveletsand applications.Joseph D. Lakey (Dept.of Mathematics,Texas A&M Univ.,College Station, TX 77843-3368) Constructionof orthogonaland biorthogonal wavelets as well asredundant wavelet frames will bereviewed. Fast computational wavelet-basedalgorithms will beoutlines and their performance will becompared with Fourier-based algorithms. Various applications of waveletanalysis in speechcompression and speech recognition, as well as broaderapplications in acousticsignal processing includingalenoising and transient analysis, will be discussed.
9:00
2aSP2.Wavelet packets as a tool for soundprocessingß Ronald Coifman (Dept.of Mathematics,Yale Univ., 10 HillhouseAve., New Haven, CT 06520) Waveletpacket analysis of soundcorresponds to an optimized musical transcription in which the sound is organizedin different structures(orchestration), each of whichis describedby a "musicalscore." This representation is a superpositionof waveletpackets (notes)of differentduration, pitch, location in time,and amplitude. Fast algorithms permit real-time transcriptions with a minimal numberof notes.In thistalk we will givea precisedefinition of thesestatements as well as applicationsto audiocompression, denoising,recognition, and modeling.
ContributedPapers
9:30 preventan incorrectdiagnosis, new methods for bloodflow velocimetry are needed.This paperpresents a techniquefor bloodflow velocimetry 2aSP3.Composite wavelet transform and frames. WadeTrappe and usingwavelet transforms, and it comparesthis technique to theconven- JosephD. Lakey (Appl. Res. Labs,Univ. of Texas,P.O. Box 8029, tionalnarrow-band Doppler methods often applied. Ultrasonic signals with Austin,TX 78713-8029and Dept. of Math., Univ. of Texas,P.O. Box highfractional bandwidths and/or large time-bandwidth products are pro- 8029, Austin, TX 78712 and Texas A&M Univ., College Station,TX cessedwith wavelettransforms. By applyingwavelet transforms, many 77843) narrow-bandassumptions typically invoked when measuring blood flow Motivatedby the humanauditory system, a new signaltransform is maybe removed. With the wavelet method presented, instead of measuring presentedwhich models the way humanshear. Cochlear processing acts theDoppler shift associated with the reflection of a signal,the time-scaling like a constantbandwidth bank of filtersin the low frequencyrange but is of thesignal is obtainedalong with theround trip traveltime. This time of proportionalbandwidth at higherfrequencies. This new transform, scalingmore accurately reflects the effects of motionon thesignals than whichwe call the composite wavelet transform, isbetter able to modelthis doesa Dopplershift since a Dopplershift is an approximationto time processthan standard signal processing techniques such as theshort-time scaling.The continuous wavelet transform is then used to obtainthe axial Fouriertransform (STFT) andthe continuouswavelet transform (CWT). velocityof scatterers. The compositewavelet transform in fact providesa signalanalysis tool thatis ableto examinesignals with competingsignal structures whereas the STFT andthe CWT do not.In orderto insurestable signal recovery, the 10:00 theo• of framesis examined.An overviewof thetheory of frameswill be givenand wavelet and Gabor frames will be discussed.Recent work on 2aSP5. Signal and echo arrival-time estimationusing wavelets. framesfor thecomposite wavelet transform will alsobe presented.Finally, PhillipL. Ainsleigh (Naval Res. Lab., UnderwaterSound Reference Detachment,Orlando, FL 32856-8337) someapplications of frames,especially to speechsignal processing will be considered. A wavelet-basedmethod is introducedfor estimatingthe arrival times of signalsand echoes observed in noisymultipath environments. This 9:45 problemarises when trying to modelany signal containing overlapping 2aSP4. One-dimensional blood flow measurement methods: segmentsof directand reflected components. The methodpresented is moregeneral than cepstrum-based techniques since it is notlimited to Narrow.band versus wideband/wavelet transform techniques, Lore echoesthat are scaled replicas of thedirect signal. The statistic•of lhc G. Weiss (Appl.Res. Lab., Penn State Univ., State College, PA 16804) waveletcoefficients are derivedfor pyramid-algorithmwavelet decompo- The goalof bloodflow velocimetryis to obtainan accuratemeasure- sitions,and theseare employedin a statisticaldetection algorithm for mentof thevelocity of th• bloodas it flowsthrough a blood vessel. If the obtainingthe arrival-time estimates. The method will beused to estimate measurementtechnique underestimates the bloodflow velocity,then the signaland echo arrival times in dataobserved during underwater trans- measurementmay appear normal and an occlusionmay go undetected.To ducercalibration esperiments conducted in smallpressurized tanks.
3287 d. Acoust.Soc. Am., Vol. 97, No.5, Pt. 2, May1995 129thMeeting: Acoustical Society of America 3287
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 10:15 11:lS
2aSP6. A wavelet method for estimating frequency-dependent 2aSP9. Time-frequencyanalysis techniques exploiting the harmonic dampingin structures. Gary R. Wilson (Appl. Res. Labs.,Univ. of •!ationshipsof outsidesound source emissions, for the purposeof Texas,P.O. Box 8029, Austin,TX 78713-8029) detection and classification, John C. Mosstug and Mohammad A. Karim (Dept.of Elec.Eng., Univ. of Dayton,300 CollegePark, Dayton, Estimation of damping ,rom the measurementof the vibrations or OH 45469) acousticradiation of structuresprovides some insight into energy storage and dissipationmechanisms in the structure.Because damping is typically Acousticsensors can be usedto passivelydetect, track, and identify proportionalto frequency,a methodof estimatingdamping that scales with non-line-of-sightsound sources. The soundsources discussed in thispaper frequencyis suggested.A waveletapproach has been taken to exploitthe containstrong harmonic components and range from being "pseudo" stfi- naturalscaling properties of waveletsto estimatefrequency-dependent riousryto transientin nature.This researchproject investigates the useof damping.A wavelettransform, the dampedcomplex exponential (DCE) varioustime-frequency analysis techniques for the pmpt•e of selecting transform,has been designed specifically for measuringdamping JR. D. featuresto be extractedfrom the acousticsignatures of motorizedsound Pdebeand G. R. Wilson,IEEE ICASSP3, 205-208 (1994)]. This trans- sources.Acoustic data were filtered and digitized using a commercially form hasbeen applied to stimulateimpulse response frequencies to deter- available analog-digitalconvertor. The short time Fourier transform mine its accuracyand sensitivityto mismatchbetween the assumed (STFT) wasused as the initial identifier,followed by narrow-bandpeak damping/frequencyratio used by the wavelet transformand the actual detectionalgorithms used to selectpeaks above a userdefined SNR. When damping/frequencyratio of the impulseresponse. It hasalso been applied sufficient"nonsmeared" peaks exist, these peaks are used to generatea set to the measuredimpulse response of a fluid loadedthin elastic shell. of harmonicallyrelated features which are input to a bayesianquadratic Resultsof thesemeasurements show reasonable agreement with theoretical classifier.When the signalbecame more "nonstationary"and the use of predictionsof damping. the STFT resultedin excessive"smearing," wavelet and Wigner-Ville analysistechnique were employed. Results are presented high!ighting the 10:30-10:45 Break trade-offsof thesetime-frequency analysis techniques. Additional results are presenteddiscussing the harmonicrelationship algorithm employed to 10:45 normalizethe frequencyshifts (due to rotor/engineRPM fluctuations) which exist in this type of signaturedata. 2aSP7. Use of wavelet template analysis for condition monitoring of rotational machine elements. David C. Swanson, Karl M. Reichard, and Michael B. Van Dyke (Appl. Res.Lab., PennState Univ., P.O. Box
30, StateCollege, PA 16804) 11:30 Rotationalelements of machinery,such as bearingsand gears,have 2aSPI0. Improved soundlocalization employing modified wavefront been shownto exhibit specificvibration signalspectral patterns over vari- reconstruction. StevenD. Trautmann (Center for Cornput.Res. in ous stagesof failure, associatedwith certaindefect frequencies character- Music andAcoust., P.O. Box 9675, Stanford,CA 94309) istic of the elementsand their components.It hasbeen demonstrated that duringadvancing stages of wear, spectralpeaks at defectfrequencies are Audio wavefrontreconstruction is similar to visual holographyin accompaniedby increasingnumbers of sidebandsof otherdefect frequen- whichoptical wavefronts are reconstructedby reproducingphases and cies. In this paper,the use of wavelet templateanalysis to characterize amplitudesto createthe impressionof an objectbeing present when it is vibrationsignals of defectiverotational elements is presentedas a method not there.In audiothere are far fewerspeakers than necessary to exactly for identifyingand quantifying element wear' The premise of thisapproach reproducea wavefrontthis way. In orderto constructthe closetpossible is that the dynamicsof a worn componentare characterizedby an increas- approximationto a desiredwavefront, information about the-listening en- ing degreeof variationaround its rotationalfrequency as the component vironmentsuch as the number, placement and qualities of theloudspeakers degradesat its pointsof contactwith other components,resulting in a andthe nature of localreverberation can be used.The perceivedquality of vibrationsignal analogous to a frequency-modulatedsignal. thisapproximation can be improvedby usingpsychoacoustical properties of soundlocalization, such as treating amplitude as morevital thanphase, 11:00 ear,and head filtering, precedence effects and masking. Thus despite lim- 2aSPS. Detection and characterization of blade-vortex interaction ited numbersof loudspeakers,improvements can be madein soundlocal- noise with wavelet analysis. Wyatt O. Davis (Dept. of Mech. and izationfor quadraphonicand stereo systems, especially at low frequencies. Mater. Eng., WashingtonState Univ., Pullman, WA 99164-2920), This is doneby usingsignal processing techniques including partial in- CharlesPezeshki (WashingtonState Univ., Pullman,WA 99164-2920), versefiltering of the acousticalenvironment to eaueelout unwantedroom and Marianne Mosber (NASA Ames Res. Ctr., Moffett Field, CA reverberation,and a criterionapplied to a raultidimen•ionalsystem in 94035-1000) orderto minimizethe maximumdifference relative to the desiredpercep- tion anywherea listenermight be located. A discreteimplementation of the wavelettransform (WT) was usedto analyzeblade-vortex interaction (BVI) noisein acoustichelicopter noise signals.A BVI detectionalgorithm was developed which takes advantage of the prominenceof BVI noisein certainsubbands. Isolated-BVI signals 11:45 wereconstructed by detectingimpulsive BVI eventsand extracting them from the subbands.Four metricswere testcAfor cultabilityas BVI cstima- 2afiPll, Audio compressionbased on sine-crussingrepresentations of tots.Two of these,the rmslevels of the isolated-BVIsignals and a metric signals. MichaelL. Hiltonand Prasanjit Panda (Dept.of Cornput.Sci., computedfrom theA-weighted frequency spectra of the isolated-BVIsig- The Univ. of SouthCarolina, Columbia, SC 29208) nals,were seen to characterizeBVI noiseseverity, but werecomputation- ally expensive.The othertwo metricswere computedfrom the amplitudes The samplingtheorem of Bar-David[J. Bar-David,Info. Control24, of the BVI eventsin the subbands.The first, basedon the exponential 36-44 (1974)]provides an implicit representation of bandlimited signals behaviorof the amplitudesacross subbands, failed to characterizeBVI usingtheir crossingswith a sine function.This sinefunction is chosenin noise severity for certain signalsand was highly sensitiveto noise. The a way that guaranteesa uniquerepresentation of the signal.On a finite second,computed from the amplitudesof BVI eventsin a singlesubband, signal,this leads to a multiplicativerepresentation involving a Rieszprod- wasan effective BVI estimatorand was relatively insensitive to noise.This uctwhose roots form the representation of theoriginal signal These roots estimatoris especiallyconvenient because it is easily usedas a decision canbe encodedto providehigh-quality, near lossless audio compression. thresholdin the detectionalgorithm, thereby making possible simultaneous The sinecrossing representation can alsobe combinedwith the wavelet BVI detection and characterization. ramsformto providefurther compression. [Work supported by ONR.]
3288 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3288
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp WEDNESDAY MORNING, 31 MAY 1995 CONGRESSIONAL HALL B, 8:30 A.M. TO 12:00 NOON
Session 2aUW
UnderwaterAcoustics: Signal Processing(Poster Session)
Jeffrey L. Krolik, Chair Departmentof Electrical Engineering,Duke University,Box 90291, Durham, North Carolina 27708-0291
ContributedPapers
All posterswill be on displayfrom 8:30 a.m.to 12:00noon. To allowcontributors an opportunityto seeother posters, contributors of odd-numberedpapers will be at theirposters from 8:30 to 10:15a.m. and contributors of even-numberedpapers will be at theirposters from 10:!5 a.m. to 12:00 noon. '• ß
2aUWl. Unambiguousnoise and reverberationmeasurements from 2aUW3.Appearance of elasticwave contributions in high •solution a dual llne horizontalarray. BruceK. Newhall (JohnsHopkins Univ., acousticimages. GregoryKaduchak, Chad M. Wassmuth,afd Charles Appl. Phys.Lab., Laurel,MD 20723), WalterS. Aliensworth (AppL M. Loeffler (Appl.Res. Labs., Univ. of Texas,P.O. Box 8029, Austin, TX Hydro-AcousticsRes., Inc., Rockville, MD 20850), and Iman W. 787i 3-8029) Schurman(Johns Hopkins Univ., Laurel, MD 20723) Studiesinvolving plane wave scatteringby finite cylindricalshells at Singlehorizontal line arraysare often utilized to resolvethe azimuthal obliqueincidence display monostatie echo contributions from surface elas- characterof the low-frequencynoise dominated by long-rangeshipping tic waves.These waves follow helicalpaths along the shell'ssurface and sources.However, such arrays are subjectto an azimuthalambiguity on are guidedback in the sourcedirection after reflectionfrom the cylinder conjugatebearings. Coherent beamforming of an array composedof two truncation[X.-L. Ban, J. Acoust.Soc. Am. 94, 1461-1465 (1993)]. The parallelhorizontal lines was recently employed to eliminatethis left/right presentresearch examines such effects viewed in the time recordof a high ambiguityusing a minimumvariance adaptive algorithm with single-point resolutionsonar system. The targetconsists of a finitecylindrical shell with main responseconstraints under an assumedhorizontally isotropic noise a radius to thickness ratio of 5%. The shell is immersed in water and is field. The ability of this array and beamformerto resolvethe directional subjectto bothexterior and interior fluid loading.It is ensonifiedwith short characteristics of the acoustic noise field was demonstrated in the Atlantic tone bursts of narrow beam width over a range of incidence angles andthe Mediterranean.Median !eft/right rejection of 20 dB or morewas 90•>&•>50, where q5is measuredrelative to the cylinderaxis. The back- observedover a wide frequencyand azimuthal band. The measuredbeam scatteredecho signature exhibits prominent artifacts as a resultof scatter- noiseexhibits temporal and spatialvariability that couldnot havebeen ing processesinvolving the so anda 0 Lambwaves interacting with the quantifiedwith a single-linesystem. Median noise gain improvements of cylindertruncation. The echocontributions are extremely sensitive to the up to 7 dB abovethat of a single line were measured.Distant low- angle of incidenceand interior fluid loadingwhich may assistin target frequencyreverberation ambiguity resolution was also measured using the classification schemes. reverberationfrom signals underwater sound (SUS) explosive charges de- ployed in the Atlantic. Reverberationleft/right rejectionof 20 dB was ZaU3V4. An approach to matched field processingin correlated achieveddespite imperfect, nonparallel line tow conditions. multipath environments. RobertZeskind (The MITRE Corp.,7525 2aUW2. Reverberation characterization and suppression in the Colshire Dr., McLean, VA 22102-3481) and Mark Owen presenceof channel spreading. Geoffrey S. Edelson (Lockheed (PRESEARCH, Inc., Fairfax, VA 22031} Sanders,Inc., MAN6-2000, P.O. Box 868, Nashua,NH 03061-0868) and Ivars P. Kitsteins (SACLANT UnderseaResearch Centre, Viale San Matchedfield processing (MFP) is basedon sometype of comparison Bartolomeo,400, 1-19138La Spezia,Italy) of actualreceived signal across the elementsof an arrayto predictedarray elementresponse based on complicatedpropagation models for postulated In activesonar. the reverberationplus taxget time seriescan be modeled sourcelocations. It is well knownIhat thesetechniques are very sensitive as the joint convolutionof the signalwith the channeland scattererim- to modelmismatch. Investigators have proposed modified MFP techniques pulseresponses. Especially in shallowwater, the channelresponse cannot of varying complexityto be more robustto mismatch.A simplifiedap- be adequatelymodeled as propagationover discretepaths. We proposea proachto MFP in a correlatedmultipath environment is to estimatethe maximumlikelihood type approachfor estimatingthe arrivaltimes of parametersof thepath arrivals at thearray based on anassumed wavefront signalswhich have propagated via a continuumof paths,i.e., temporally modelfor eachpath. The parametersto be estimatedaxe arrival angles, spreadchannels. The channelspreading is includedin the modelby using relativereceived level for eachpath, and the correlationcoefficient be- a discreteprolate spheroidal sequence (DPSS) to representthe channel tweenpair of paths.For sphericalwavefronts, the distancetraveled along impulseresponse of givenduration, but unknownshape. Thus the un- eachpath is alsoestimated. It is assumedthat there are only a few domi- knownpararneter• are the arrivaltimes and the _eealefactors of the DPSS nant pathsand their numberis known. The parameterestimation problem expansion.The parametersare estimatedusing an iterativemethodology is posedas a well-knownoptimization problem. The solutionto the opti- which decomposesthe originaldata into its constituentcomponents and mizationproblem not only actsas a detector,but providesthe set of then estimatesthe parametersof the individualcomponents through a estimatedparameters to be usedin a raytracepropagalion model to back sequenceof one-dimensionalsearches. Experimental data and computer propagatethe multipathto localize the detectedtarget. An example is simulationexamples indicate that the methodperforms well. presentedto illustratethe method.
3289 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3289
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 2aUW5. Multiple-frequency robust adaptive matched-field search.An efficientforward model will be describedfor an experimental procesnlng(MFP) in shallowwater. YungP. Lee (ScienceApplications configurationinvolving a sourceand a verticalarray separatedby up to International,Inc., 1710Goodridge Dr., MS TI-3-5, McLean,,V A} severaltens of wavelengthsin range.The operatorsof the self-starterand thesplit-step Pad6 solution are combined into a singleoperator that acts on Applicationof robustadaptive algorithms to multiple-frequencyMFP a delta functionto give the field on the array. Oa a parallel-processing in shallow water has been studied and the minimum-detectuble-level computer,this approachprovides the replicafield in the computationtime (MDL) has been examinedvia simulations.The multiple-frequencyMFP it takes to solve a single tridiagonalsystem in a conventionalparabolic outputis obtainedby incoherentlyaveraging the MFP outputsof the dis- equationalgorithm. This efficiencygain is not achievedby sacrificing cretenarrow-band-components. Performance of threedifferent averaging accuracy.The approachtypically involves the solutionof aboutten tridi- techniques(arithmetic-mean, geometric-mean, and harmonic-mean) have agonalsystems. Finite-difference based separation of variablessolutions been compared.The arithmetic-meanaverages the amplitudes,the typicallyrequire the solutionof hundredsor thousandsof similartridiago- geometric-meanaverages the dBs, and the harmonic-meanaverages the nal systems.The efficiencyof the rapid forward model will be demon- reciprocalsof the amplitudes.These algorithms have been applied to shal- stratedfor the matched-fieldinversion problem of estimatingthe param- low water data from the HudsonCanyon experimentand have demon- eters of the ocean bottom. strated excellent source localization results. simulations show a 10- to 20-dB improvementin the MDL againstthe simulatednear or distant 2aUW9. Localizing a source buried in noise in an uncertain surface noise. environment. Laurie T Fialkowski and Michael D. Collins (Naval Res. Lab., Washington,DC 20375) 2aUW6. Fisher information for fluctuating intensity and the efficiencyof logarithmicmeasures. NicholasC. Makris (NavalRes. A sourcein an uncertainenvironment may be localizedusing localiza- Lab.,Washington, DC 20375) tion, which involvesa parameterspace that includesboth sourceand en- vironmentalparameters. A sourceburied in noisemay be localizedusing The optimalresolution of a setof parametersto be estimatedfrom a set noise-cancelingtechniques, which involve matching both signal and noise, of measurementsof fluctuatingintensity can Ix: determinedby computing or eigen-processingtechniques, which are capableof extractingsignals the respectiveFisher information matrix. This matrixis dependentupon from noisydata. These techniques have beencombined to solvelocaliza- the conditional distribution of the fluctuating intensity measurements, tion problemsinvolving a sourceburied in noisein an uncertainenviron- giventhe parametersto be estimated.It is assumedthat fluctuatinginten- ment.Noise-canceling techniques requires knowledge of the noise.Since it sity is measuredfrom circular complex Gaussian random (CCGR) fields. may not be practicalto model the noiseas part of the parametersearch, it Such fields are commonly measuredin acoustics,optics, and radar. For is assumed that the noise covariance matrix is obtained from data taken example,CCGR fieldstypically arise in scatteringfrom fluctuatingtargets whenthe sourceis not present(mismatch associated with temporalenvi- and surfaces,random sources,and ocean-acousticpropagation scintilla- tion.Distributions for intensity,log-intensity, and acoustic flow (analogous ronmentalvariability is includedin the simulations).Eigen-processing to opticalflow) are derivedas a functionof the measurement-systemav- techniquesare lesseffective than noise-canceling techniques at suppress- ing noiseand requiresource motion when multiplesources axe present. eragingtime and the temporalcoherence of the fluctuatingficld under the CCGR field assumption.(This advances previous work in ocean-acoustic However,they havethe advantageof not requitinga priori knowledgeof the noise. propagationscintillation that was limited to instantaneousmeasurements.) It is shownthat the Fisherinformation for a measurementof'fluctuating 2aUW10. Fast inversion of the ill-conditioned shallow water intensityis expressedin termsof parametervariations over the-expectation propagationoperator for pulsedsignals. JacobRoginsky (Acoust. value of a logarithmicmeasure of intensity.This gives a mathematical Div., Naval Res. Lab., OverlookAve., S.W., Washington,DC) and G. justificationfor the engineeringintuition that fluctuatingintensity should W. Stewart (Univ.of Maryland,College Park, MD) be measuredin logarithmicunits to efficiently conveyinformation. A gen- eralizedFisher information matrix is derivedfor the estimationof param- Time seriesdeconvolution in underwateracoustics is a difficult prob- etersfrom intensityimages. lem dueto the practicallysingular nature of the propagationoperator. The situationis evenmore complicated in thepresence of a multipathenviron- 2aUW7. Parameter estimation bounds for acousticintensity images. ment.In particular,when the time windowis shorterthan the propagation NicholasC. Makris (Naval Res. Lab., Washington,DC 20375) time, the processrequires the solutionof a largetriangular Toeplitz system A generalizedCramer-Rao lower bound is derivedfor the estimation that is quite ill conditioned.Satisfactory results can be obtainedby trun- of parametersfrom intensityimages. It is assumedthat the intensityas- catingthe singular,valuedecomposition (SVD), but only at the costof signedto eachpixel value in an imageis measuredfrom a circularcomplex ignoringthe Toeplitz structure. The objectof thiswork was to investigate Gaussianrandom (CCGR) field. Suchfields are commonlymeasured in the alternativeof usingTicbonov-Phillips mgularization to lessenthe ef- acoustics,optics, and radar. However, intensity images obtained from fectsof theill conditioning.An algorithmof LarsEldrn [SIAM J. Sci.Stat. acousticmeasurements generally have lower SNR thanin opticsor micro- Cornput.5, 229-236 (1984)]that takes advantage of theTceplitz structure wave radar,making parameter estimation more difficult. This is because can be adaptedto this purpose.The results'are as goodas thoseobtained acousticcoherence time scalesare generallymuch larger than thosein fromthe SVD, but the cost is O(n 2) in the matrix size as opposed toO(n 3) opticsor microwaveradar relative to the respectivestationary time scales. for theSVD. For theproblems considered here, this amounts to a speedup Therefore,it is especiallyimportant to determinethe practicalityof the of two ordersof magnitude. parameterestimate by determiningthe optimalresolution attainable. Vari- 2aUWll. Matched-field replica model optimization and bottom ousanalytic bounds are derived including those for estimationof scattering propertyinversion using multitone signills. in shallowwater. PaulA. strength,transmission loss, the orientationof a Lamberttansurface by Baxley (Oceanand AtmosphericSciences Div., Acoust.Branch, stereoscopicanalysis. the locationand recognitionof an object,the NCCOSCRDTE Div. Code 541, 53560 Hull St., San Diego,CA !utiouof blurredfeatures in a set of images,and the motionor acoustic 92152-5001),and Newell O. Booth (NCCOSCRDTE Div., SanDiego, flow (analogousto opticalflow) of an objectover a seriesof blurred CA 92152-•001) images.The applicationspresented are for underwaterimaging systems, but the formulationis generallyapplicable to arbilrarybeamformed imag- Matched-fieldreplica modelsbased on an inaccurateknowledge of ingof CCGRfields. This work is directly applicable topattern recogniiion. geoacousticparameters such as bottom attenuation,shear, and interfacial 2aUWS.A rapid forward modelfor •natched-fieldinversion. R. sound-speeddiscontinuities, can predictan incorrectnumber of propagat- Cederhergand Michael D. Collins (Naval Res. Lab., Washington,DC ing modesfor a shallow-waterchannel. The resultingdegradation in the 20375) matched-fieldambiguity surface can he substantiallyreduced by optimiz- ing over the modal-sum-limitused in the replicamodel. The use of this The forwardmodel is an importantcomponent of a matched-fieldin- techniquefor multitone(70. 95, 145, and 195 Hz) source-towdata re- versionalgorithm. The forwardmodel must be efficientbecause it is often cordednear San Diego duringthe first shallowwater evaluation cell ex- necessaryto computea largenumber of replicafields during the parameter periment(SWeIIEX-I) significantlyincreased matched-field correlation
3290 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of Amedca 3290
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp levelsfor all narrow-bandtones (and their average),with the maximum 2aUWI5. Broadband matched-field source localization with a peak.more frequently coinciding the correctsource location than that ob- horizontalline array in shallowwater. W. S. Hodgkiss,J. J. Murray, servedwith a previousnonoptimized model [Schey and Ryan, J. Acoast. K. H. Kim, andG. L. D'Spain (MarinePhysical Lab., Scripps Inst. of Soc.Am. 95, 2981A(1994}]. The predicted number of propagatingmodes Oceanogr.,La Jolla,CA 92093-0701) wasalso reduced substantially. An inversionfor bottom properties (attenu- SWellEx-3(shallow water evaluation cell experiment#3} wascarried ation,interfacial sound-speed discontinuities, no shear}provided sediment out in July 1994west of PointLoma in approximately200 m water.A MPL auenualionestimates which agreewell with Hamilton'smodels and were 64-elementvertical array wasdeployed from the R/P FLIP and the NRaD an orderof magnitudegreater than that usedin the nonoptimizedmodel, SWSS(shallow water sensor string) horizontal line arraywas codeployed which accounts for the reduction in the number of modes. A simulated 500 m to the east.The focusof thispaper is on broadband(70-370 Hz) modeldecomposition using the new attenuationverifies the numberof matched-fieldsource localization with the SWSS horizontalline array. modespredicted by the modal-sum-limitoptimization. Examplesof processingresults from a CPAevent near endfire using a 300 m subapertureof the HLA will be presented.In order to betterunderstand 2aUWI2. Broadbandmatched-field processing of low level signalsin theseresults, a comparisonwill be madewith the resultsfrom similar shallowwater. NewellBooth and Phil Schey (Oceanand Atmos. Set. processingof thedata collected by theVLA overthe sameperiod of time. Div., NCCOSCRDTE Div. Code541, SanDiego, CA 92152-5001) In addition,simulations of the SWeI1Ex-3environment will be presented showingthe effecton the matched-fieldambiguity surface of increasing Matched-fieldprocessing analysis is presentedfor multitonesignals theHLA aperture.[Work supported by ONR, Code321.] from the shallowwater evaluation cell experiment/13(SWeI1Ex-3) which 2aUWI6. Minimum variance matched-field source localization with was carried out in July 1994 west of Point Loma in 200 m water of complex bathymetry.The multitonetest signal was transmittedfrom an SACLANT Mediterraneansea trial data. JeffreyL. Krolik (Dept.of Elec. Eng., Duke Univ., Box 90291, Durham,NC 27708) acousticsource towed at variousdepths over tracksdesigned to test matched-fieldprocessing replica generation over complexpropagation The minimumvariance (MV) adaptivebeamformer has been widely paths.The multitonesignal consistedof 5 sets of 10 tones,each set proposedfor matched-fieldprocessing because it providesa meansof spanned50-200 Hz and was transmittedat various levels with 22-dB suppressingambiguous beampattern "sidelobes." In thispaper, the perfor- dynamicrange. Using noise level estimatesobtained at frequenciesbe- manceof threerobust MV methodsis evaluatedusing vertical array data tweenthe tones,the inputsignal + noise-to-noiseratio is estimated.Bar- from the MediterraneanSea collectedby the NATO SACLANT Centre tlett and minimumvariance distortionless response (MVDR) adaptive northof Elba[D. E Gingrasand P. Gerstoft, J. Aeoust. Soc. Am. 96, 3234 matched-fieldprocessing results are presented from this data set over vari- (1994)]. The three MV methodsconsidered are (I) the reducedMV ouspaths for inputsignal to noiseratios spanning + 12 to -l0 dB. method(RMV) [C. L. Byrneet el., J. Acoust.Soc. Am. 87, 2493-2502 (1990)],(2) theMV methodwith neighborhoodlocation constraints (MV- 2aUWI3. Effects of ship trim and dynamic attitude on the relative NLC) [H. Schmidtet al., J. Acoust.Soc. Am. 88, 1851-62 (1990)],and noise level measured by a hull-mounted multibeam bathymetric (3) theMV methodwith environmental perturbation constraints (MV-EPC} sonar. C. deMoustier (Marine Physical Lab., Scripps Inst. of Oceanogr., [J. Krolik, J. Acoust.Soc. Am. 92, 1408-19 (1992)]. Real data results La Jolla, CA 92093-0205) indicatethat each approach has different merits. Projecting the dataonto the reducedspace defined by the modaleigenfunctions as in the RMV is Acoustic data recorded in various sea conditions with the hull-mounted necessaryto avoidinstabilities caused by highlycorrelated noise. Using multibeamswath bathymetrysystem SeaBeam 2000 aboard R. ¾. neighboringlocation constraints as in the MV-NLC reducesthe need to finely samplethe ambiguitysurface. And usingconstraints derived from MELVILLEhave been analyzedto quantify the relationshipbetween the ship'sattitude and the relativenoise levels observable in the data.The data the second-orderstatistics of the signalwavefront averaged over an en- sembleof perturbedenvironmental parameters as in the MV-EPC increases consistof concurrenttime seriesof echomagnitude and direction of arrival robustnessto environmentalmismatch. [Work supported by ONR.] for each transmissioncycle, and of the three attitudecomponents roll, pitch, and heave.Although higher noiselevels are usuallyassociated with 2aUW17. Mirages in shallow water matched-fieldprocessing. G.L. pitch, in thesedata heavehas the greatestimpact on noiselevel, presum- D'Spain, J. I. Murray,W. S. Hodgkiss (Marine PhysicalLab., Scripps ably becauseof bubblesyphoning from the areatedsurface layer. In addi- Inst. of Oeeanogr.,San Diego, CA 92152-6400), and N. O. Booth tion, a slight changein the trim of the ship from horizontalto bow up (NCCOSCRTDE Div., SanDiego, CA 92152-5001) resultsin an averagerelative noise increase of about 12 dB. [Research Broadband(50-200 Hz) matchedfield processingwas performedon supportedby ONR.] verticalline arraydata from a recentshallow water experiment. Although 2aUWI4, Gradient-basedreceiver structuresfor deteclingsound the actualwater depthsteadily decreased from 200 to 100 m over the directions.Terry L. Hendersonand Terry J. Brudner (Appl.Research sourcetow track, the replicavectors were calculatedassuming a range- Labs., The Univ. of Texas,Austin, TX 78713-8029) independentenvironment of 200 m depth.Rather than breaking up dueto the increasinglysevere environmental mismatch, the broadbandmatched field outputpeak in rangeand depth behaved in a consistentway; boththe The use of a pressuregradient microphone for detectingthe source predictedrange and depth of the sourcebecame increasingly greater than directionof an incidentplane wave is well known.Furthermore, any re- its true rangeand depthas the true water depthdecreased. A simpleana- ceiving aperturethat appliesa specifiedapodization can be regardedas lyticalmodel was developed to predictthe behaviorof theseMFP mirages. extractinga point-sampleof a spattallyfiltered versionof the iocidenl The goodagreement between model predictions and actual results suggests wave.Our resultis thatwhen the gradientmethod is appliedto the spattally thatthe modelcan he usedto quantifythe impactof unknownwater depth filteredwave (which is alsoa planewave), the answer can be expressedin changes(e.g., ocean swell on syntheticaperture studies) and to "calibrate" termsmodified apodizations, formed from the originally specified apodiza- water depth in a region using the sinking miragesof surfaceships of tion functionand its vectorgradient, integrated over the originalaperture opportunity.By useof theconcept of "effectivedepth" developed by D. E. and/orits boundary,together with simpletemporal filters. Fortunately, this Westonet al., the modelalso can be appliedto studiesof oceanbottom seeminglycomplicated structure collapses to a muchsimpler one in many geoacousticparalneter mismatch. [Work supported by ONR, code321 .] casesof interest.and it is evenpossible to extendthe methodto the higher order case in which two or more wave directions are detected simulta- 2aUWI8. Robustnessand resolution of a ray travel time inversion scheme. I-Tat Lu (PolytechnicUniv., Route I10, Farmingdale,NY neously.Alternatively, one wavedirection can be measuredwhile steering 11735) a broadbandnull in anotherspecified direction, and the steered-nulldirec- tion can be altereddynamically even after beamforming.Examples are A ray travel time inversionscheme has been developednot only for given.Our resultsare especiallyapplicable to transientsounds of arbitrary localizingthe sourceand calibrating the arrayposition, but alsofor char- bandwidth.[Work supported by ARL:UTIR&D.] acterizingenvironmental parameters such as sound-speedprofiles in both
3291 J. Acoust.Soc. Am., Vol.97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3291
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp water column and sediment[I-Tai Lu, J. Acousc Soc. Am. 95, 2983A 2aUW22. Nonambiguous beamforming for a high resolution (1994)]. Here, we will presentthe detailedstudies of robustnessand reso- twin-line array. JeanP. Feuillet (Spaceand Naval WarfareSystems lution of this method. Command,Washington, DC 20999), Walter S. Aliensworth (Appl. Hydro-acousticRes., Inc., Rockville, MD 20850), and Bruce K. 2aUW19, Broadband hydrophone calibration below I MHz. Gerald Newhall (JohnsHopkins Univ., Laurel, MD 20723) R. Harris, Jeffrey M. Porter, Paul M. Gammell, and ChristopherA. Patton (FDMCDRH,12721 Twinbrook Pkwy., HFZ-132, Rockville, MD 20852) Technologyof towedline arraysand associatedsignal processing has progressedin recentyears to thepoint that wideband multiline array co- Recentcalibration efforts for miniaturehydrophones used to measure herentsignal processing can now be performedin real time.Earlier imple- medicaldiagnostic ultrasound fields have been devotedto increasingthe mentation(1993) of a multilinearmy beamformercentered around the upperfrequency range of calibration(>10-15 MHz). However,a band- ability to conytire a conventionalline arraybeam response with thatof an width extendingto at least 10 times belov•the diagnosticpulse center orthogonaldipole. Performance of this implementationprovided a unique frequencyis neededfor accurate(error •5%) measurementof the peak nonambiguousrighffleft beam with roughly -20-dB energyrejection in rarefactionalpressure and mechanicalindex, both importantquantifies. the null steereddirection over a significantrange of verticalarrival angles. Since at presentno commemialhydrophones for medicalultrasound use However,performance suffered significantly with otherthan straight and providesensitivity information below 1 Ml-lz, a studywas undertakento paralleltowed lines. Recent (1994) implementationof a beamformerfor a determinethese low frequencysensitivities. The techniqueuses broad- twin-linetowed army has shownthe ability to form deepbacklobe nulls band,plane-wave pressure pulses generated by electricalshock excitation (-37 dB). Implementationof thisbeamformer is similarto the MVDR of a thickpiezoceramic disk. The hydrophoneresponse is calculatedfrom methodexcept an isotropicnoise field is assumedin the horizontalplane. measurementsof the soumetransducer and hydrophonevoltage wave- This techniqueallows for uniformsuppression of sidelobesat all off-MRA forms. The frequencyresponses of both needleand membranepolymer azimuthdirections while maintainingbacklobe rejection and MRA shape. hydrophoneswere measuredusing this technique.The membranehydro- Spatialweights are adaptivelycalculated based on the estimateof the phonesstudied had bandwidths extending below •0.2 MHz, but oneof the twin-line array shape.This methodhas beenshown to be robustfor non- needleprobes began rolling off above0.5 MHz. Therefore,given the above paralleland dissimilar shapes. criterionregarding diagnostic pulse center frequency, sensitivity to 0.1-0.2 MHz shouldhe establishedfor diagnosticuse hydrophones,because a 2aUW23. Shallow water active sonar 'ssues. William Carey (ARPA, uniformresponse below 1 MHz cannotbe assumed. 3701North Fairfax Dr., Arlington,VA 22203) and PeterG. Cable (BBN SystemsTechnoi., New London,CT 06320) 2aUW20. Broadband guide source helps localization in shallow water. MartinSidedus, Darrell lackson, and Robert Porter (Appl.Phys. Lab., Univ. of Washington,Seattle, WA 98105) The central questionsin sonar systemdesign concern the limits of coherentprocessing and are:What is the optimumfrequency range and Acousticmeasurements from a broadbandguide sourceare usedin a bandwidth?;How largeof a receivingaperture is required?;What is the highlyvariable shallow ocean to augmentsparse environmental informa- achievabledetection range? These questions are determinedby the propa- tion. The conceptof using a broadbandguide sourceis inspiredby the gationand scatteringof sound.In the shallowwater channel, under down- astronomicaltechnique in which light from a staris usedto correctatmo- ward refraction,the bottomis the determinantfactor. A parametricsonar sphericaberration of a nearby(in the angularsense) object. The acoustic equationunder reverberation limited conditionsshows two factorsare im- techniqueinvestigated here is similarto holography[P. D. Moumdet al., portant,the effectivebottom back scatterstrength and the coherentsignal J. Acoust.Soc. Am. 92, 1031-1039 (1992)] in whicha verticalarray of gain.A parametricanalysis is presentedthat focuseson the frequency- continuouswave (cw) referencestatues is usedto localizeunknown tar- dependentcharacteristics of the bottombackscattering strength and the getsby reconstructingthe wavefrontat the locationof the referencesource effectof coherenceon receivingarmy aperture. Several recent reverbera- array,removing much of thedistortion caused by theocean. Mourad et al. tion andsignal coherence measurements are presentedand the needsfor showedthat this method is effectivewhere the adiabatic approximation is futurestudies are delineated.The backscatteringstrength is shownto be valid.The presenttechnique differs by usinga singlebroadband guide stronglyfrequency dependent and to dependon thedepositional sediment sourcein shallowwater where mode coupling can occur.In this work, we layer.The coherenceis alsofound to dependon frequencyand range as developa methodsimilar to holographyvalid for strongrange-dependent determinedby signalgain measurements. environments,together with singlehydrophone matched field methodsto solve the source localizationproblem. Numerical simulationsare also 2aUW24. Acoustic calibration of shallow underwater explosive givenfor a varietyof environmentsto demonstratethe effectiveness of the charges. PeterG. Cableand William J. Marshall (BBN Systemsand method.[Work supported by Officeof NavalResearch.] Technoi.,Union Station,New London,CT 06320-6147)
2aUW21. Source depth dependenceof misma•h-induced range and Broadbandunderwater acoustic measurements are oftenperformed us- depth localization errors in conventional maShed-field processing. ing explosivecharges as sources.For moderateweight charges detonated GeorgeB. Smith (NavalRes. Lab., Code 7173, Stennis Space Center, MS 39529-5004), Murty A. Akundi (Xavier Univ. of Louisiana,New at shallowdepths the bubblepulse oscillation period can exceed the sepa- ration betweendirect and surfacereflected arrivals for any source-to- Orleans,LA 70124),and NichalosD. Gardner (MississippiState Univ., MississippiState, MS 39762) receivergeometry. Because of the overlapof multipatharrivals with the time signatureof the charge,a directdetermination of free-fieldsource In previouswork [Smith and Akundi, J. Acoust.Soc. Am. 95, 2980(A) levelsand spectral characteristics for sucha situationcan be problematical. (1994)] analyticexpressions for mismatch-inducedrange localization error In order to perform acousticcalibrations of explosivecharges in shallow andsignal gain degradation for a lineareorrelator matched-field processor water,a methodhas been developed that uses the multiplearrivals on a were obtained.Those resultsagreed with previouslyobtained results verticalreceiving array of hydrophonesseparated from the sourcedetona- [Shangand Wang, J. Acoust.Soc. Am. 89, 2285-2290 (1991)].!n this tionby oneor twowater depths. The technique involves averaging the time work the problemsof mismatch-induceddepth localization error and the seriesfrom the vertical array phones after time aligningthe directshock sourcedepth dependence of bothrange and depth localization errors are arrivalson all the phones.This focusedbeamforming method has been addresscA.Computer simulations show that the analyticpredictions ob- usedto obtainsource calibrations from dataobtained during area charac- tainedhere are not perfect but are close enough to indicatethat this line of terizationtest 1I (ACTII) in water50 fathomsdeep using 4 lb CompB researchis on theright track. [This work was supported by theOffice of chargesdetonated at 25 fathoms.High levels of consistencyand repeat- Naval Research,Program Element 61153N, with technicalmanagement abilitywere obtained from several sources detonated at differentranges providedby the Naval ResearchLaboratory, Stennis Space Center, Mis- fromthe array. The calibrationtechnique will be describedand illustrated, sissippi,The NAVY/ASEEsummer faculty research program, and by the andthe achievable precision of themethod discussed. [Work supported by MAMP program.] ARPA underthe Adverse Environments Program.]
3292 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3292
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 2aUW25. Pressureeffects on the dynamic and static propertiesof localization,the measuredcorrelagram is comparedwith a correlagram perforated elastomersused in underwater acoustics. Stepbane producedby a broadbandnormal mode model using the derivedsource Beretti (DCN IngenierieSud, Dept. of UnderwaterWarfare, BP 30, 83800 track.[Work supported by theOffice of NavalResearch (Code 322).] ToulonNaval, France), ChristianAudoly (DCN lag. Sud., Toulon, 2aUW28. Autonomous environmental measurement system, J.M. France),and Philippe Guillaussier (PONS, 13872 AubagneCedex, Stevenson,J. R. Olson, and B. J. Sotirin (Acoust.Branch, Code 541, France) Naval Command, Control and Ocean Surveillance Center, RDT&E Div., SanDiego, CA 92152-6435) The microinhomogeneousmaterials made with air-filledcavities in For experimentplanning and optimized array deployment, experiment viscoelasticmatrices, have many possibleuses in underwateracoustics plannersand array designers often seek a quick,affordable means to help includinganechoic coatings, acoustic decoupling, or reflectorsfor arrays. determinebest placement of a underwateracoustic measurement system Theoreticalmodels are necessary to predictthe acoustic properties of these priorto deployment.Array design geometry relative to ambientnoise lev- materialsby evaluatingthe propertiesof the equivalenthomogeneous ma- els andvariability, seafloor morphology, currents, and water column struc- terial,as a functionof frequency,pressure, and temperature.During recent ture(e.g., ducts) is aidedby a priori knowledgeof the setting.It is desir- worksan abnormaleffect of the appliedpressure on thesematerials was able to determinesome of theseunknowns before undertakingthe time and noted:The plot of the longitudinalsound speed and of the bulk modulus, effort of a systemdeployment. Likewise, experiment planners and array versusstatic pressure, had the lowestvalue for 10 to 20 barsof applied designerswould like to be ableto exploredeployment schemes that are pressure,instead of a regularincreasing plot predicted by themodels [G. locallyoptimized for the environmentin orderto reducesensor sparseness in criticalareas. This presentationdescribes an expendable,inexpensive Gaunaurdet al., J. Acoust.Soc. Am. 76, 173-177 (1984)]. Differentre- sensorsuite installed approximately one week prior to the deploymentof sults,including test panel measurement in a tank,or measurementof the an underwateracoustic measurement system. The instrumentcollects en- staticand dynamic bulk modulus agree with this consideration. Theoretical vironmentaldata and providesadvanced information to the experiment modelsto predictthe staticand dynamic effective material properties as a plannersprior to a finaldeployment, facilitating optimized placement of functionof the pressurewere compared with theseresults. the measurementsystem. Parameters sampled include: Variability and av- eragelevel of ambientnoise, SVPs, seafloor type and sediment thickness, 2aUW26. Nonlinear transformationsfor spatial matched filtering surfacewave heights,tidal measurements,and watercurrents. Character- (detect-on-track). Yung P. Lee (ScienceApplications International istics of the systemdescribed include its small size, low weight, low Corp., 1710 GoodridgeDr., McLean,VA 22102) and Haw-JyeShyu power,affordability, and simple,low-bandwidth data collection scheme (Naval Res. Lab., Washington,DC 20375) basedon slackline arraytechnology. [Work supportedby ONR, Code 321.] A detect-on-trackalgorithm based on the Hough transformhas been 2aUW29. Target range and depth estimation from surface appliedto acousticbroadband correlograms for passivedetection and lo- multipath. James A. Doutt (Dept. of AOPE, Woods Hole calization.The Houghtransform integrates (sums) the amplitudes along a OceanographicInst., Woods Hole, MA 02543)and EdwardH. Hug (Old setof delaycurves of interest.The delaycurves are calculated over a range Ironsides,Inc., New London,CT 06320) of closestpoint of approach(CPA), speed,and headingof the targets. Whennormalized by thenumber of points,the Hough transform computes Therange and depth of a targetare determined and compared with the the arithmetic-meanalong the track. This processis referredto as an knowndepth and the rangeas derivedfrom differentialGPS navigation. The dataconsists of a singlereturn from a monostaticsonar configuration. arithmetic-sum(AS) transform.This AS transformoptimally reducesthe The methoduses a cost functiondefined as the sum of the squaresof the varianceof the noise,but can alsogenerate significant ambiguous side- differences between the arrival times measured from the data and those lobes.To reducethe sidelobe,two nonlineartransforms are proposed:The predictedby ray tracefor an assumedtarget depth and range. The depth logarithmic-sum(LS) transformand the harmonic-sum(HS) transform. andrange are thenvaried so as to minimizethe cost function. Only the The LS-transformsums dB's while the HS-transformsums the reciprocal directand surface-reflected paths have been used. However, the method is of the amplitudesalong the track.When normalized by the numberof easilygeneralized to usemore arrivals if thebottom depth is knownand points,the LS transformcomputes the geometric-meanand the HS trans- bottom-interactingarrivals can be identified. formcomputes the harmonic-mean along the track. Simulations show that 2aUW30.Results on the sequentialclassification of sphericalobjects the nonlineartransforms perform the sameas the AS transformin noise- in shallowwater. RogerF. Dwyer (Naval UnderseaWarfare Center, limitedenvironments but outperform the AS transformin sidelobe-limited New London, CT 06320) environments. Basedon the theoreticalresults reported in [J. Acoust.Soc. Am. 93, 2aUW27, Shallow water source track localization using matched 1460(1993)] andthe simulated results reported in [J. Acoust.Soc. Am. 96, multipath correlations. D. 1ZKnobles, Evan K. Westwood,and K. C. 3312(A)(1994)] an experiment to determinethe performance of sequential Focke (Appl.Res. Labs., The Univ. of Texasat Austin, Austin, TX 78713) classifyingspherical objects in shallowwater has been carried out. The shallowwater data were obtained from experimentsoff the EastCoast of A methodfor localizinga broadbandmoving source using the signals the UnitedStates in 1993.Five sphericalobjects of differentcomposition receivedon a horizontalplanar array is presented.The methodinvolves wereembedded in shallowwater data and the performance of a sequential findingthe constant-velocity, straight-line soume track that generates the classifierto correctlyidentify the objectswas obtained. The performance resultsof thesetests using standard measures of effectivenesswill be leasterror between measured and modeledcorrelation traces over a period reported. of time.Measured correlation traces are obtained by cross-correlatingmul- tiplepairs of receivedtime series. Simulated correlation time delays are 2aUW31. Efficient acoustic-fieldcomputations for matched-field obtainedusing a raymodel that includes the effects of refractionon the ray inversionfor geoacoustlcproperties. S. E. Dosso,N. R. Chapman arrivaltimes. A nonlinearoptimization routine is usedto obtainthe best (DefenceResearch Establishment Pacific, FMO Victoria,BC V0S lB0, matchin measuredand simulated time delaysover time andreceiver pair. Canada), R. G. Racca, and N. G. Henson (JascoResearch Ltd., The mainproblem in shallowwater is to identifywhich multipath pair• BrentwoodBay, BC V8M IP7, Canada) producethe correlation traces observed in themeasured data. An approach Matched-fieldinversion for sourcelocation, environmental properties, [or oremorningthis problemthat involvestesting multiple hypotheses or a combinationof the two (localization)is basedon comparingmeasured concerningthe multipath pairs will be presented.An exampleapplication acousticfields to replicafields predicted for a varietyof possibleenviron- of the method to a shallow water datasetwith three bottom-mountedre- mentalparameters and/or source positions using a numericalpropagation ceiversin a triangularconfiguration is presented. In orderto validatethe model.Although this approach is conceptuallystraightforward and widely
3293 J. Acoust.Soc. Am., Voh 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3293
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp applicable,it requiresa largenumber of replica-fieldcomputations and can characteristic,the analysisof the coherencein a real experimentcan be be impracticallyslow ff the propagationmodeling is not carriedout in an usedto determinethe dominantcontribution. An exampleon a submarine efficientmanner. This is particularlytrue for environmentalinversion and will be given. focalizationwhere the expanded parameter search space generally requires a very large numberof replica field computations,even if a relatively 2aUW33, Large-array acoustic signal processing in random efficientoptimization algorithm such as simulatedannealing (SA) is em- deep-water channels:Effects of coherence. AlexanderI. Malekhanov and AlexanderG. Sazontov (Inst. of Appl. Phys.,Russian Acad. of Sci., ployed.This paperdescribes malebed-field inversion for geoacousticprop- 46 Ul'yanov St., 603600Nizhny Novgorod,Russia) eries using SA and rapid acoustic-fieldmodeling. The replies-fieldmod- eling is basedon the normal mode solutionand makesuse of multivariate Approximateanalytical solution of the matrix transportequation for interpolationof precomput•d"look-up" tablesof modalquantities stored the mutual coherencefunction (MCF) of an acousticfield in terms of as a functionof the geoacousticparameters. The optimumgrid-element normalmodes was derived. The proposedapproach is capableof including size for the modal tables is considered,and two interpolationschemes, sl•chasticaflyrough surface as well as volumefluctuations in the indexof linearand Shepard's method (locally quadratic), are investigated.An ex- refraction,and allowed one to reducethe problemof the MCF calculation ampleis givenof geoacousticinversion in a North Pacificenvironment. in a refractivechannel to the analogousproblem in a free space.These 2aUW32, Sonar array self-noise analysis using hydrophone resultshave been then employed to simulatethe statistical effects of long- cross-correlationfunctions. Christian Audoly (DCN Ing6nierieSud, range soundpropagation in realisticdeep-water environments from the Dept.LSM, B.P.30, 83800Toulon Naval, France) North-WestPacific on the horizontalarray detection performance for sev- eral beamformingtechniques. The most attentionwas paid to the gain The performancesof acousticarrays for passivesonar systemsare degradationfor the soundfrequency of 250 Hz over megameterranges limited by ambientnoise and by self-noisephcnoraena, such as turbulent underthe basicassumption that internalwaves or surfacewind wavesare, flow-inducednoise, machinery noise propagating along the hull, or pro- respectively,the main sourceof acousticsignal fluctuations. Rough surface pellornoise. To predictthe performances of the systemand to improvethe scatteringhas been shown to causethe mostsignificant effects. In particu- designof the arrays,it is importantto determinewhich self-noise corppo- lar, for the arraylength of order 100 acousticwavelengths and wind speed rtent is dominant on a given ship at different speeds.This paper will of 15 m/s tbe coherenceloss was of about6 dB even for optimalquadratic presentthe behaviorof the typical coherencefunctions between the hy- processorand, in comparison,of about12 dB for conventionalplane-wave drophonesof a flank array, for the different noise components.As the beamformer.[Work supportedby RussianBasic Research Foundation, evolutionalong sensor separation and/or frequency for eachcomponent is GrantNo. 9•02-04544a.]
WEDNESDAY AFTERNOON, 31 MAY 1995 MEETING ROOM 16, 1:30 TO 4:05 P.M.
Session2pAA
ArchitecturalAcoustics: Health and Legal AspectsRegarding the Use of PorousMaterials
Richard H. Talaske, Coohair The TalaskeGroup, Inc., 137 North Oak Park Avenue,Oak Park, Illinois 60301
Angelo J. Campanella,Cochair CampsheilaAssociates, 3201 RidgewoodDrive, Columbus,Ohio 43026
Chair's Introduction•l:30
Invited Papers
1:35
2pAAI. Fiberglasshealth and safetyupdate: Moving beyondthe science. Rick Vetsen (SchullerInternational, Inc., P.O. Box 6•gO0•, Littloton, 120 õ0162)
Fiberglasshas provided numerous acoustical and insulation benefits for over50 years.Today, engineers, architects, and specifiers mustweigh the benefits derived from various products against the potential risks that may be involved. During the past several years significantefforts have been undertaken to evaluatethe potential health hazards and risks associated with exposure to fiberglass materialsto facilitatemeaningful benefit/risk analyses. Large studies of workersand variousanimal tests have been conducted and reviewedby numerousgroups and agencies. While many scientists believe that the research indicates that fiberglass is not very hazardous,if at all, to humans,others contend that it maybe just as harmfulas asbestos.While disagreement among scientists is nothingnew, the confusionand controversy created in the mindsof nontoxicologistsand epidemiologists observing the debatesis unfortunate.Comfort should be taken in theextensive weight of thescientific evidence that is availableon thisimportant material. Mostimportant, we shouldunderstand the limitations of scienceand focus on the handling and use recommendations which can assure the safeuse of fiberglassproducts.
3294 d.Acoust. Soc. Am., Vol. 97, No. 5, Pt.2, May1995 129thMeeting: Acoustical Society of Amedca 3294
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 1:55
2pAA2.Weight of scientific evidence approach shows fibrous glass presents little public health risk. CharlesW. Axtcn (Healtb, Safety,and Environmental Affairs, North America Insulation Manufacturers Assoc., 44 CanalCtr. Plaza,Ste. 310, Alexandria, VA 22314) To date,several scientific research studies have been published discussing the health effects of exposureto fibrousglass. Although themajority of thesestudies have failed to demonstrateany causal association between exposure to fibrousglass and adverse health effects,the materialhas nevertheless been classified/labeled as a "possiblecarcinogen." This paperdiscusses the basisfor this classification/labelaswell asa morerealistic "weight of theevidence" approach to evaluatingthe scientific data on fiberglass.Using suchan approach and integrating the substantial toxicological, epidemiological, exposure, and chemical data accumulated on fibrous glassover the past 50 years,one is ledto theconclusion that the material poses little, if any,risk to thepublic health under normal conditions of use.
2:15
2pAA3.Porous insulation in HVAC systems.Philip R. Morey (ClaytonEnvironmental Consultants, Inc., 1729 Christopher Ln., Norristown,PA 19403) Porousinsulation used to linethe air streamsurf3•ces of HVAC equipment provides a locusfor theaccumulation of dirt and debris. Dirtand debris are hydrophilic and the insulation on the air stream surfaces of mechanicalcooling systems thus provides a niche for moldgrowth. The moldgrowing on porousinsulation unlike moldy debris on a hardsurface such as sheetmetalcannot be removed byduct cleaning. Actions for proactively preventing biocontamination of HVAC insulation include the following. (l) Porousinsulation shallnot be used to linethe air streamsurfaces of HVAC piehumswhere wetting is likelysuch as in thevicinity of coolingcoils, water spraysystems, humidifiers, and other sources of water.Porous insulation may, however, be used in theseHVAC components provided thatthe insulation is separatedfrom moisture sources by a barrierthat is both air andwater tight. (2) Becauseof possiblemold growth, the useof porousinsulation should be minimizedon the air streamsurfaces in mechanicalventilation systems where the relative humidityconsistently exceeds 65%.
:
2:35
2pAA4.ASHRAE sound and vibrationtechnical committee position statement on the useof fiberglassin HVAC systems. RussellA. Cooper(Jaffe Holden Scarbrough Acoustics, Inc., 114A Washington St.,Norwalk, CT 06854) Fiberglassduct liner continues to bethe most cost-effective solutions to noisecontrol in mostHVAC air duct systems. There has beena recentincrease in thenumber of institutional,educational, and medical projects for whichthe use of fiberglasshas been banned or severelylimited. The decisionsare based on concernsthat the fibers may be carcinogenicand that the products may promote microbialgrowth. This paper will presentthe ASHRAE TC2.6 (Sound & Vibration)technicalcommittee's response to thesedevel- opments,describe the state of themedical research and briefly outline alternatives and the consequences of duct lining removal from HVAC systems.
2:55
2pAA5.Measurement of shredded mineral fibers. PerV. Bhiel (BriielAcoust. ApS, GI. Holtevej97, Denmark) Throughoutthe world there has been a desireto testmineral wool for the shredding of mineral fibers. There is a generalconcern, thatsound absorption materials, consisting of fibers made of rockor glass, are damaging even in smallamounts. Until now a standard methodfor thetesting of acousticalabsorbers has not been found. This paper shows a testchamber and describes a method for the objectivemeasurement of shredded fibers. This method is simpleand fast to carryout and shows a levelof accuracy,which seems betterthan earlier attempts.
3:15
2pAA6.Nonfibrous air andgas flow silencers and sound absorbers. Martin Hirschorn (Industrial Acoust. Co., 1160 Commerce Ave.,Bronx, NY 10462)and Uno Ingard (MIT, Cambridge,MA) Post-WWIIjet aviation,air conditioning, quieter working and living conditions, and OSHA legislation necessitated new noise controlproducts largely based on fibrous sound absorptive materials. In June 1994 the U.S. Di•partment ofHealth and Human Services announcedthat fiberglass isa material"reasonably anticipated tobe a carcinogen."Non fibrous silencers, noise suppressors, andsound absorbershave already been developed, for reasonsunrelated to thisannouncement, for over 40 years--longerwhen automobile mufflers,Maxim silencers, and Helmholtz resonators are considered. Nonfibrous aircraft ground jet enginenoise suppressors provide superioracoustic performance and durability. Nonfibrous HVAC silencers and sound absorbers are u•;ed in medicaloperating rooms andothers requiring a risk-free environment. The design of nonfibroussilencers, rooms, sound absorbers, and encapsulated fiber designsforvarious acoustical requirements willbe discussed. Mostsound absorptive materials lend•'hemselves wellto mathematical modeling.Absorption characteristics ofa variety of future absorber configurations, including their nofilinear behavior inintense sound fields,will bepresented. Such designs are often perfected by meansof laboratorymodels tests, with airflow if applicable,before finalization.For certainnonfibrous duct liners, the possibilityof negativeinsertion loss must be considered.
3:35-4:05
PANEL DISCUSSION
3295 J. Acoust.Soc. Am., Vol. 97, No.5, Pt. 2, May1995 129thMeeting: Acoustical Society of America 3295
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp WEDNESDAY AFTERNOON, 31 MAY 1995 GRAND BALLROOM CENTRAL, 2:00 TO 5:30 P.M.
Session2pAt
AcousticalOceanography: Acoustical Determination of Ocean Processes
Michael D. Richardson, Chair Naval ResearchLaboratory, Stennis Space Center, Bay Saint Louis,Mississippi 39529-5004
Chair's Introduction--2:00
ContributedPapers
2:05 acousticwavelength but largeenough that the liquid viscosityis insignifi- cant,the potentialflow approximationis reasonable.The naturalfrequency 2pAt1. Effects of salinity on the acousticsof bubble plumes. of bubblessurrounded by sedimentgrains of comparablesize are com- GregoryJ. Orris and Michael Nicholas (Naval Res. Lab., Washington, puted by a boundaryintegral formulationallowing in detail for bubble DC 20375) deformationand the presenceof rigid boundaries.Even thoughthe geom- A previouspaper [J. Acoust. Soe. Am. 95, •826(A) (1993)]presented etry is restrictedto axisymmetriccases, main features of thisprocess are acousticdata collected near bubble plumes of variousvoid fractionsand adequatelycaptured by simulatinga numberof cases.Several configura- sizesproduced by varyingthe flow velocityof a waterjet impinging tionsare tested and, in manyinstances, substantial differences between the normallyon a watersurface. Subsequent analysis has revealedthat the currentcalculations and the commonlyused 'formula have been found. data'sspectral content varies considerably between the two phasesof the [Worksupported by theOffice of NavalResearch.] experiment--oneinvolving fresh water in Lake Washingtonand the other involving salt water in Puget Sound.In the fresh-waterportion of the experimentthe spectraare completely dominated 'by modescorresponding 2:50 roughlyto the grossdimensions of the plume.In the salt-waterportion of the experiment,the saltsand other contaminants (which act as surfactants 2pAt4. Bubble size distribution measurement using an inverse and lower the surfacetension) dramatically reduce the meanbubble size acoustic scattering technique: Theory and experiments. Ramant with respectto that of freshwater. The acousticdata froni the salt-water Duraiswami,S. Prabhukumar,and GeorgesL. Chahine (Dynafiow,Inc., experimentare drasticallydifferent from thatof the freshwater, and show 7210 Pindell SchoolRd., Fulton,MD 20759) little or no modal structure.For this particularphysical situation it is suggestedthat the dominantacoustic generation process is likely to be Determinationof thebubble population in liquidsis an importantprob- turbulence.Furthermore, differences in the acousticsignature$ of the ex- lem in manyfields. Acoustic methods have advantages over other methods perimentcould be exploitedto determine,amongst other things,the con- of measurementin that bubblesare very responsiveto sound,that reason- centration of the salts and contaminants. ably largevolumes may be sampled,and that the methodcan be relatively inexpensive.However, previousattempts at using acousticalmeans of measurementhave not led to weil•establishedmeasurement techniques due 2:20 to the ill-posednature of the problem.In the presentwork, a multiphase modelfor soundpropagation through bubbly liquids is usedto obtaintwo 2pAO2. Dfi-eetnumerical simulation of the acousticbehavior of integralequations of the firstkind for'determining the bubbledistribution bubbleclouds. M. Watanabeand A. Prosperertl(Dept. of Mech.Eng., from measuredphase-velocity and attenuationdata. New algorithmsfor JohnsHopkins Univ., Baltimore, MD 21218) regularizationof the ill-posedproblem by imposinga numberof physical The descriptionof a bubbleassembly. or cloud,by meansof an "ef- constraintsin a directminimization setting are developed.These algo- fectivemedium" approximation has found widespread application in the rithmshave beentested on analyticaldata with varyingartificial noise underwateracoustics community. In this approachthe bubbly liquid is added,and foundto be successful.Based on this techniquea new bubble regardedas a continuumendowed with propertiesdifferent from thoseof measurementdevicesthe acousticbubble spectrometer (ABS) is being the pureliquid. In this studythe' effective medium results are compared developed.The device is being comparedin a seriesof testswith other with those of a direct numerical simulation in which the effects of the methods of bubble distribution measurement such as venturi cavitafion mutual interactionof the bubblesare simulated.A sphericalassembly of susceptibilitymeters, and microphotography.Results from theseexperi- bubbles immersedin an incompressibleliquid is studied.The potential mentswill be presented.[Work supported by NSF.] problemis solvednumerically with a singularityexpansion method includ- ing both volume pulsationsand translationaloscillations of the bubbles. Numericalresults for both single realizations and ensemble averages are 3:05 presentedand discussed.[Work supportedby the O[tlce of Naval Re- search.] 2pAOS. A semianalytical method for the noise emission of finite size objectsin shallowwater. HasanN. Oguz (Dept.of Mech.Eng., Johns 2:35 HopkinsUniv., Baltimore,MD 21218)
2pAt3. A theoretical study of natural frequenciesof bubbles in Pointsources are commonlyused in underwaterambient noise com- sediments. AndreaProsperetti and HasanN. Oguz (Dept. of Mech. putationsto modelwave breakingnoise. A semianalyticalsolution to Eng.,Johns Hopkins Univ., Baltimore,MD 21218) soundemission by a finitesize object in shallowwater is developed.The coefficientsof thenormal modes obtained by thistechnique are compared Bubblesthat are highlyefficient scatterers have dramatic effects on the with the coefficientsgiven by the pointsource approximation for thecase acousticcharacteristics of sediments.The incorporationof sucheffects in of a hemisphericalbubble cloud. The comparisonis only goodwhen the continuummodels requires the knowledge of individualbubble frequency sizeof the bubblecloud is muchsmaller than the acoustic wavelength. and responseto acousticwaves. For bubblesthat are smaller than the Substantialdifferences occur when the radiationpattern near the bubble
3296 J. Acoust.Sec. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3296
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp clouddeviates from a circularshape associated with the point dipole emis- attenuationbetween identical radial-poled ceramic cylinders (two transmit sion.Accurate normal modes coefficients given by the currentmethod andtwo receive).Shear wave velocity and attenuation are measured using couldbe coupledwith shallowwater propagation models used in ambient a similar pulsetechnique. Bimorph bender elements mounted in flexible noisecalculations. [Work supported by theOffice of NavalResearch.] siliconerubber mounts and drivenat 100 to 2000 Hz to generateshear waves.Values of sedimentgeoacoustic properties from muddysediments of Eckernf6rdeBay, Baltic Sea and carbonatesediments of the Florida Keys presentedused to illustratethe operationand utility of the new 3:20 system. 2pAO6. A modelfor underwaterambient noise at low wind speeds. HasanN. Oguz (Dept.of Mech.Eng., Johns Hopkins Univ., Baltimore, MD 21218) 4:15 When the wind speedis low enough,wave breakingdoes not lead to bubble clouds of substantial size. The collective mode of oscillations that 2pAO9. Using shear waves to predict the liquefaction potential of seafloorsediments. JamesPyrah and Angela Davis (Schoolof Ocean is dominantat high wind speedsmay be neglected.In this case,wave Sci., Univ. Collegeof North Wales,Menai Bridge,Gwynedd LL59 5EY, breakingthat is still the major sourceof noiseis approximatedby a finite UK) areaof the sea surfaceover which singlebubbles are entrainedand emit individualacoustic pulses. Each breakingwave has a certain emission Thereis growingevidence to supportthe useof the seismicshear wave characteristicsdepending on bubblesize distribution,density, wave size, velocityas a predictorof seafloorsediment liquefaction potential. At the rate of entrainment,etc. An empiricalcorrelation between the whitecap UniversityCollege of North Waleslaboratory experiments are beingper- coverageratio and the wind speedis employedto infer the size of the formedto determinethe steady-statecharacteristics of a varietyof nonco- bubble entrainment area. The contribution of all waves are summed and hesivesediments. The conventionallaboratory approach involves an in- theambient noise levels are computed as a functionof thewind speed. The vestigationof void ratio/effectivestress relationships, and providesan resultsare in goodagreement with fieldmeasurements. [Work supported indicationof the sediment'slikely behavior---contractiveor dilative-- by the Officeof Naval Research.] whensubjected to cyclic shearstresses such as thoseimposed by earth- quakeor water wave loading.In the testscurrently being carriedout at UCNW, the shear wave velocity is also being monitoredto establish
3:35 velocity/voidratio/effective stress relations which offers the possibilityof extrapolatingthe laboratoryfindings to the field situation.Thus givena 2pAO7. Depth-dependentgas fractionsin acousticmodels of marine knowledgeof the in situ shearwave velocity,grain characteristics,and sediments.Frank A. Boyleand Nicholas P. Chotiros (Appl.Res. Labs., staticstress regime, it becomespossible to providean estimateof the Univ. of Texas,P.O. Box 8029, Austin, TX 78713-8029) sediment'sstability under cyclic load conditions.
Models have recentlybeen developedfor acousticscattering from trappedgas bubbles in sandyand silty marine sediments IF. A. Boyleand N. P. Chotiros,J. Acoust.Soc. Am. 96, 3219 (A) (1994) andF. A. Boyle 4:30 and N. P. Chotiros,J. Acoust. Soc. Am. 94, 1766 (A) (1993)]. These preliminarymodels may be somewhatlimited in applicabilitydue to an 2pAO10. Determination of vertical correlation lengths in a channel assumptionthat the bubblesare distributedhomogeneously throughout the using SWELLEX-1 thermistor data. T. Barnard and M. J. Beran half-spacebelow the sedimentinterface. Observations suggest that actual (Dept. of Elect. Eng., The CatholicUniv. of America,Cardinal Station, sedimentsare horizontallystratified, and that gas fractionshave strong Washington,DC 20064) depth dependence.The models have therefore been modified to allow In orderto properly determine the volume scattering in a channel,it is specificationof a depth-dependentgas fraction.Studies suggest that the necessaryto know the characteristicvertical and horizontalcorrelation backscatteringstrength is significantlyaffected, with considerableinflu- lengthsassociated with the randomindex-of-refraction fluctuations. The enceon its grazing angle dependence. [Work supported by NavalResearch resultswe have obtainedfor characteristicvertical correlation lengths us- Laboratory,Stennis Space Center under the MCM TacticalEnvironmental ing SWELLEX-I vertical-arraythermistor data are discussed.The data Data System(MTEDS) project.] havebeen analyzed for day-timeand night-timeobservations. In addition, the resultsare dependentupon averaging times and this effect is discussed. Graphsare givenfor the standarddeviation and normalizedcross correla- 3:50-4:00 Break tionsof the fluctuations,as a functionof depth.[The verticaltemperature data analyzedin this presentationwere producedby NRL Code 7120 and NRAD Code541 underONR sponsorship.The datawere supplied to usby 4:00 B. Poseworkof NRL Code7120. Our analysiswas supportedby ONR.] 2pAO8. Recent developmentsin the in-situ measurementof sediment geoacousticproperties. MichaelD. Richardson(Naval Res. Lab., SSC,
MS 39529-5004) and ScanR. Griffin (Omni Technol.,Inc., Metairie, LA 4:45 7000l) 2pAOll. Using Rytov acoustic wave modeling to test ocean The latestversion of the in-situsediment acoustic measurement system variability models. Terry E. Ewart and Daniel Rouseff (Appl. Phys. (ISSAMS) allows direct, in-situ measurementof sedimentgeoacoustic Lab. and Schoolof Oceanogr.,Univ. of Washington,Seattle, WA 98105) properties.Geoacoustic probes, which are mountedon a rigid frame, are insertedinto the sedimenthydraulically. The entire operationis controlled Stochasticacoustic models of acousticphase propagation were usedto and monitoredin real-time from the surface.Data is collectedand pro- validateocean internal wave modelsin Ewart andReynolds [SPIE Press, cessedby a wet-sidecomputer and transmittedto the surfacefor waveform PM09(April 1993)]. In thatw6rk Rytov modeling of thephase variability displayand analysis.Video camerasboth monitor insertion of probesand providedvery accurateagreement with a linearocean internal wave model. providepreliminary indication of sedimenttype. A seabirdCTD is usedto Suchtests require extreme accuracy in the phasemeasurements and hence measurebottom water temperature,salinity, and soundspeed. Sediment very accurateposition stability in the acousticarrays. In the AIWEX compressionalwave velocity and attenuationare measuredover path- acoustictransmission experiment the phasevariability was so small that lengthsof 40 to I10 cm and at depthsof between0 to 50 cm belowthe millimetersof motionof the arraywere significant in the phasevariance. sediment-water interface. Pulsed sine waves am transmitted at 58-kHz and When the propagationis in the Rytov regimefor both the phaseand log time delaysand voltagesare used to determinevalues of velocity and amplitudevariability, the amplitudeshould be equallyusable to test sto-
3297 J. Acoust. Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3297
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp chasticocean models. In this work we developthe Rymv modelfor the while the soundis transmittedthrough the Kuroshiofront. [Work sup- caseof variabilityin the soundvelocity profile and a nonconStantVaisala portedby NationalScience Council of RePublicof China.] frequencyprofile wherethe scintillationindex of the acousticfluctuations
indicatesthat Rytov modelshold. Simulated linear internal wave fields and 5:15 PE propagationare usedto generatethe complexwave fields. The stochas- tic inversefor the phaseand log amplitudeis comparedwith the input 2pAO13. Three-dimensionalultrasonic imaging of temperature transversespectrum of internal waves. The regimesof applicabilityof distributions.V. I. Mirgorodsky,V. ¾. Gerasimov, and S. V. Peshin thesemethods, the directions of furtherresearch, and the incr'rporation of (Inst. of Radioeng.and Electron.of RAS, Fryazino,141120 MoscOw thesetechniques in the conductof traditionaloceanographic measurements Region, Russia) to enhanceour ability to interpretthe internal wave environmentwill be discussed. The investigationof the new opportunityof an acoustothermometer's spaceresolution realization is described.The methodis basedon the cor- relationprocessing of signalsreceived by the multi-elementpiezotrans- 5:00 ducer.It is convenient toillustrate the method by the example ofa recep4 2pAO12. Mode coupling effect of Kuroshio front in Taiwan's tion of the signalsirradiated by a pointnoise source by meansof the two NortheastSea. ChifangCben (Dept. of Naval Architectureand Ocean spacedtransducers. The mutualcorrelation function of thesesignals has a Eng., National Taiwan Univ.: 73 Chou-Shan Road, Taipei, Taiwan. maximumgt the delay that is proportionalto thepath's difference between Republicof China) the signal's.source and piezotransducers.Space resolution that is deter- minedby the correlation maximum's width is about a coherencelength Of The Kuroshiocurrent turns toward the northeastwhile it passesthe thereceived •ign•als. Atthe easily achieved frequency bandof the received OkinawaTrough in Taiwan'sNortheast Sea. In this region.there are dif- signals(--1 MHz) it maybe of a relativelysmall value (--0.1 cm).The ferent watersmixing, namely,water from the Taiwan Strait, water of the analyticalsolution of the problemof spacedistribution of noncoherent EastChina Sea, and the Kurnshiocurrent. During the year,except in the radiation'ssources by useof correlationprocessing of signals received by summermonths. the Kuroshiocurrent is characterizedby •itsdistinct tem- variouselements of the transducersis presented.The opportunityof real- peraturedifference from other waters. i.e., the Kuroshiofront is a predomi- izationof a spaceresolution less than I cm at a distanceof about7 cm is nantfeature in thisregion. The bottomtopography in thisregion is com- shownby the computersimulation. It is essentiallybetter using a known posedof shelf and slopefeatures. The acousticspropagation is studied methodbased on the frequency'sanalysis. Results of preliminaryexperi- numericallyusing the FOR3D code. Severe mode couplingis realized mentsare presented.
WEDNESDAY AFTERNOON, 31 MAY 1995 MEETING ROOM 3, 1:00 TO 4:45 P.M. Session2PEA
EngineeringAcoustics: Transducers, Arrays, and Modeling HaroldC. Robinson,Ch•ir Naval UnderseaWarfare Center, New London,Connecticut 06320
ContributedPapers
1:00 1:15
2pEA1.Applications of the combustive sound source. Preston S. 2pEA2. An acousticalmodel of the pulse combustionprocess. Wilson,Thomas G. Muir, JohnA. Behrens (Appl. Res.Labs. Univ. Of JeffreyA. Zimmer (BBNSYst. and Technol., 70 FawcettSt., Cambridge, Texas,P.O. Box 8029, Austin,TX 78713-8029),and JanetL. Elizey MA 02138) (Univ. of Texas,Austin, TX 78712) Pulsecombustors derive many of theiradvantages asthermal devices Thecombustive so'und source (CSS) can be used to generate high- from the largeacoustic oscillations that are characteristicof the pulse intensity,low-frequency acoustic energy in a varietyof mediumsby using combustionprocess. There have been numerous attempts to modelthis deploymentConfigurations suitable toeach medium. The basic principle of processand predict the frequency and amplitude of theoscillations. Many operationremains configuration independent. A gaseous fuel/oxidizer mix- of thesemodeling efforts have relied heavily upon computation while tureis introducedinto a combustionchamber and ignited with a spark.The providinglittle in the way of explanationof the underlyingphysical ensuingcombustion produces a bubble of expandinggas which, in turn mechanism.The presentmodel treats the pulsecombustor as an acoustical systemwith feedback. Th• dependenceof the operating frequency on vari- produceshigh-intensity, low-frequency acoustic pt•!ses. Three different de- oussystem parameters is studiedthrough stability analysis. The dynamics ploymentconfiguration experiments will be discussed,including water column, ocean-bottomseismic, and earth-surfaceseismic. [n-situ measured of thecombustion event itself are characterized asa timedelay. The pres- enceof thisdelay in thefeedback loop causes the operating frequency to energylevels and spectra produced by CSS arecompared to othersources differsignificantly from the frequency one would calculate by treatingthe typicalto eachmedium, including explosive and .inertial. It is shownthat combustoras a Helmholtzresonator at resonance.Preliminary experimen- CSS is capableof producingbulk waves in bothWater and earxh mediums, tal verificationof thetheory is presented,as follows.Both the operating aswell as seismic interface waves for both air/?arth and water/sea floor frequencyand combustion time delay are measured for a pulsecombustion cases.It is demonstratedthatCSS is a truly•ersatile acoustic energy boiler,as are temperatures in the unit to establishsound speeds. When the sourcewith a low costdeployment configuration which can be tailored measuredtemperatures anddelay are inserted into the model, •t:predicts easilytodifferent environments. [Worksupported bythe U.S. Navy Office theoperating frequency to within4%. [Worksupported by The GasRe- of Naval Research.] searchInstitute.]
3298 d.Acoust. Soc. Am.i Vol. 97, No. 5, Pt.2, May1995 129thMeeting: Acoustical Society of America 3298
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 1:30 problemis presentedto modela futurePCTSCM transducer.Linear exci- tationof a PCTSCM transduceris accomplishedthrough the usualappli- 2pEA3. Noise reduction of an experimental pulse combustionwork cationof a potentialdifference across the two facesof a thin film realiza- station. JeffreyA. Zimmer (BBN Syst.and Technol., 70 FawcettSt., tion. It is shownthat sucha transducerwould launchlinearly polarized Cambridge,MA 02138) and RobertD. Collier (49 EagleRidge Dr., shearwaves with controlledpolarization. Within the transducer,the polar- Lebanon,NH 03766) ization does not, in general,follow the material inhomogeneity.Shear Pulsecombustors are pulsatingacoustical systems which radiate high- wavecharacteristics are dependent on the specificfrequency response zone intensityradiated noise. The Forbesenergy engineering experimental pulse (seeabove) in whichthe transduceris operated.[Work supportedby NSF combustorwas operatedin a "high pressuremode" at a fundamental GraduateFellowship.] frequencyof 50 Hz and an outputbetween 330 000 and 390 000 BTU/h. The noiselevels of the baselineconfiguration, measured around the ex- 2:15 haustoutlet, had an SPLover 110dB at 50 Hz anda seriesof highintensity narrow-bandcomponents up to 2 kHz. The A-weightedbroadband SPL in 2pEA6. A transduction model of lead magnesium niobate-titanate. the rangeof 100dB(A) exceededdamage/risk criterion by as muchas 25 Jean C. Piquetteand S. E. Forsythe (UnderwaterSound Reference dB. The noise reductiongoals correspondedto NC50 and SIL of 50 dB. Detachment,Naval Res. Lab., P.O. Box 568337, Orlando, FL 32856-8337) The approachconsisted of threeparts: (1) A cowl silencerinstalled at the Lead magnesiumniobate (PMN) and lead magnesiumniobate-lead outletvent for controlof mid to high frequencybroadband noise; (2) a titanate(PMNPT) are electrostrictiveceramics that exhibithigh strains customdesigned tuned low-frequency muffler installed as partof the ex- whena sampleis subjectedto a high voltage.The strainas a functionof haustalecoupler; and (3) thermoacousticcladding applied to thestructure. voltageis an almostperfect square-law over a large rangeof voltages, Thesilencer provided a reductionof 20 dB(A)in themid-frequency range neglectingsaturation and hysteresis.Unlike piezoelectricceramics, these and the muffler resulted in narrow-band reductions of 25 to 40 dB at the materialswill not accepta significantpermanent polarization, so the be- lowest frequenciesand 5 to 15 dB up to 2 kHz. The results,including havior cannotbe linearizedin this way. A transductionmodel of these soundintensity mapping, are discussedin termsof the goals,design modi- materialsbased on an analogyto the Hunt electrostatictransducer is pre- fications,and operational factors. [Work supported by The GasResearch sented.The Hunt model is generalizedfor radiation loading and for a Institute.] passivedielectric material betweenthe plates.The dielectricmodel in- cludessaturation but excludeshysteresis. The model is invertedanalyti-
1:45 cally to determinea driving-voltagewaveform which permits a PMN(PT)- basedtransducer to be drivenat high voltagein a harmonic-and transient- 2pEA4. The effects of multilayering piezoelectric plates with free manner. Successfulexperimental applications of the model to implicationto 1-3 piezocompositematerials. DavidJ. Powell (Dept. measurementsobtained from PMN(PT) samplesare presented. The results of OceanEng., Florida Atlantic Univ., BocaRaton, FL 33431), Thomas includea descriptionof a successfulattempt to drivea PMN(PT)sample in R. Howarth, and Robert Y. Ting (Naval Res. Lab., Orlando, FL a harmonic-and transient-suppressedmanner at high voltage. 32856-8337)
This paperdiscusses the considerationsof stackingpiezoelectric plates 2:30 mechanicallyin series(on topof eachother) and electrically in parallelor 2pEA7. Low-frequency underwater transducer modeling using the series.Benefits include increaseddisplacement for projectorsand in- direct global stiffness method. J. Robert Fricke and Mark A. Haynet creasedsignal-to-noise ratio (SNR) for hydrophones(because of self- (Dept.of OceanEng., MIT, Cambridge,MA 02139) shieldingand decreased electrical impedance). The presentationwill show why theseenhancements are realizedby usinga mathematicalsolution of The direct global stiffnessmatrix method(DGSM), describedby the one-dimensional(l-D) wave equationto describehow eachlayer is Frickeand Haynet[direct global stiffness matrix method for 3-D Truss relatedto thatin adjacentlayers via continuityof particledisplacement and Dynamics,submitted to theASME 15thBiennial Conference on Mechani- force.The resultantset of simultaneousequations is solvedusing matrix cal Vibrationand Noise, 17-21 September1995], provides an efficient manipulationalgorithms over a specifiedfrequency range in termsof the methodfor analyzingtwo-dimensional and axisymmetric, low-frequency, free-fieldvoltage sensitivity (FFVS), transmitting voltage response (TVR), underwater,transducer geometries. The DGSM methodis a wave-type and electricalimmitance characteristics. A temporaltransient response is solution based on the Euler-Bernoulli beam element. The mechanical mo- obtainedthrough the inversefast Fourier transform (IFI•F). This compu- tion of the transducerelement is modeled using a collection of beam tationalefficient model is capableof piezoceramicor 1-3 piezocomposite elementswelded together at joints. By imposingdynamic equilibrium con- transducerlayers, as well as inactivelayers. The 1-3 piezocompositesare ditionsat thesejoints, a bandedsymmetric stiffness matrix is formed.The inputby usingthe Smithexpressions for representingthe piezocomposite matrix is then solved using Gaussianelimination to find joint displace- as a homogeneousmaterial. Application of 1-3 piezocompositesfor mul- ments and rotationswith beam energiescalculated on a post-processing tiple layeringwill be introducedand discussed. [Work sponsored by the basis.The radiationload due to the surroundingwater is includedusing a Officeof Naval Research.] compactsource assumption. Thus fluid loadinginteraction effects, impor- tantfor low qualityfactor transducers, are properlyaddressed. Analysis of a classIV flextensionaltransducer is offeredas an exampleof the useful- 2:00 nessof this approach. 2pEAS. Axial shear wave transducer constructedof a piezoelectric continuously twisted structurally chiral medium. Steven F. Nagle 2:45-3:00 Break andAkhlesh Lakhtakia (Dept.of Eng. Sci. andMech., Penn State Univ., UniversityPark, PA 16802-1401) 3:00
The materialproperties of a piezoelectriccontinuously twisted struc- 2pEA8. In-water modal analysis using a combined finite turallychiral medium (PCTSCM) vary helicoidally along the axialdirec- elemenUboundaryelement method. ClementinaM. Sidersand M.D. tion. The quasielectrostaticapproximation was implementedfor axial McCollum (NRL, Orlando, 3909 Summerlin Ave., Orlando, FL propagationmodes in PCTSCMsiS. E Nagleand A. Lakhtakia,J. Acoust. 32856-8337) Soc. Am. 96, 3226(A) (1994)]. The following conclusionswere drawn: Axial propagationof shearmodes is affectedby piezoelectricstiffening. A combinedfinite element/boundaryelement modeling technique can Axial propagationdisplays selective attenuation and the frequencyre- be usedto analyzefluid-loaded transducers to computethe displacements sponsewas classifiedinto threezones: A zone of no attenuationand two of the structureat specifiedfrequencies. The problemwith this techniqueis handednesses(zone l); a zoneof selectiveattenuation (zone lI); anda zone that thereis no way of knowinga priori the in-waterresonance frequency of no attenuationand one handedness(zone Ill). Now, a boundaryvalue correspondingto a given in-air mode.A commonapproach is to "guess"
3299 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acousfica[ Society of America 3299
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp a frequencyrange that will encompassthe in-water resonance frequency by 3:45 usinga coarsefrequency step size. A fluid-loadedanalysis is then per- 2pEAll. Comparison of using extended-lineprojectors versus formedin this frequencyrange. By examiningthe resultingdisplacements single-elementprojectors in a water-filled traveling-wavetube. M. versusfrequency, it can be determinedwhether the resonancehas occurred K. Beasonand L. D. Luker (UnderwaterSound Reference Detachment, in the frequencyrange. If the in-water resonancefrequency is located,a Naval Res. Lab., P.O. Box 568337, Orlando,FL 32856-8337) finerfrequency step can be usedover a smallerfrequency range to deter- mine the resonanceto a betterresolution. This paperdescribes a methodto This presentationconsiders the effectof projectordesign on reducing determinethe in-waterresonance frequency of a finiteelement/boundary pressure-fielddeviations within the long-line hydrophonecalibrator elementmodel using an iterativeeigenvalue solution, thus avoidingthe (LLHC).The LLHC is a water-filledtraveling-wave tube which simulates lengthyconvergence process of a harmonicsolution. The time savings a plane-wavepressure field arrivingfrom any bearing.This is accom- between this new in-water modal solution and the traditional harmonic plishedby measuringthe electroacoustictransfer matrix between hydro- solutioncan be phenomenal.Several example problems are also presented. phonesand projectors that are placedwithin a steelpipe with an inner diameterof approximately30 cm. This transfermatrix is then usedto computeprojector drives suitable for creatingthe desired field. Two types of projectorswere investigatedfor use in the LLHC: (1) single-element projectorsusing a hollow PZT-4 spherewith an outerdiameter of 38.1 mm 3:15 anda wall thicknessof 4.76 mm, and(2) projectorlines constructed of 10 cappedcylinders of PZT-4 with 12.7 mm length,12.7 mm diameter,and 2pEA9. Near-field acoustic solution of a rotating point source in 0.79 mm wall thickness. Model simulations and measured data will be frequencydomain. HongbinJu, Menyu Sherig (Div. of Fluid Mech., presentedindicating that the extended-sourceprojectors result in lower Dept. of Eng. Mech., TsinghuaUniv., Beijing 100084,People's Republic deviationsfrom the desired pressure field than single-element projectors at of China),and FangyuanZhong (ShanghaiJiaotong Univ., Shanghai the samespacing. [Work supported by NAVSEA.] 200030,People's Republic of China) 4:00
To do researchon the aeroacousticmechanism of turbomachineryor 2pEA12. Estimation of the uncorrelatedand correlated spatial any other rotatingmachines, it is importantto studythe acousticcharac- componentsof the self-noisein towed arrays. Brian G. Ferguson, teristicsof therotating sources. Based on thefrequency domain solution of GaryC. Speechley(Defence Sci. and Technol. Organisation, P.O. Box 44, movingsound sources, an approximateacoustic solution of a rotatingpoint Pyrmont,Australia 2009), and David V. Wyllie (DefenceSci. and sourcein the nearfield, whichis the superpositionof a far-fieldsolution Technol.Organisation, APW2-316, Canberra,Australia 9600) and threenear-field modification items, is given if the rotatingradius is Theself-noise in towedarrays can be dividedinto two components on acousticalcompact when compared with the field soundwavelength. Ac- the basisof its spatialcorrelation properties. In thispaper, optimal esti- cordingly,the near-fieldGreen's function in free spaceis obtained.Then, matesof the uncorrelatedand correlated self-noise components are ob- the directionalitycharacteristics of the soundfield inducedby rotationis tainedusing an adaptivefrequency-wave-number analysis technique. The discussed,and the influenceof sourceposition, soume frequency, and resultsof applyingthe technique to realdata from various towed-array rotatingfrequency is studiedin detail.The resultsreveal that the distribu- typesare presented.The spatiallyuncorrelated contribution to the total tion of near-fieldmodifications is discretearound the viewingangle, and self-noiseis oftenignored in thepresence of thecorrelated structure-borne the influenceon near-fieldmodification by the rotatingradius happens vibrationsthat travel in bothaxial directions along the array with a phase mostlyaround the rotatingplane, while the influenceof the axial position speedthat is lessthan the speed-of-soundpropagation in the underwater of the sourcehappens mostly near the rotatingaxis. medium.The increasingimportance of the uncorrelatedcomponent at higher tow speedsis discussedand, under some circumstances,the uncor- relatedcomponent is shownto dominate.
4:15 3:30 2pEA13.Acoustic coupling in directionalloudspeaker arrays. Hahn 2pEA10. Variational modelfor the radiation impedanceof classIV Vu-Maesto,Ananda Chakravarty, Vineet Mehta, and Charles Thompson transducersII. Harold C. Robinsonand ElizabethA. McLaughlin (Ctr.for Adv.Cornput. and Telecommun., Dept. of Elec.Eng., Univ. of (Naval UnderseaWarfare Ctr., New LondonDetachment, New London, Massachusetts,Lowell, MA 01854) CT 06320) Theperformance of directional loudspeaker and microphone arrays is of interestwith regard to conferencingapplications. Transducer arrays can In a previouspaper [H. C. Robinsonand E. A. McLaughlin,J. Acoust. be steeredto enhancetransmission and or receptionat a prescribedloca- Soc.Am. 96, 3318(A)(1994)], the variationalmethod of determining tion. In reverberantenvironments, directional microphone arrays have modalradiation impedances was applied to a pair of classIV transducers. shownpromise in enhancingspeech intelligibility in hand-freeapplica- The self-and mutual radiation impedances for thequadrupole, octopole, tions. Steerableloudspeaker arrays, on the other hand, have met with andmonopole modes were presented. This paper extends the analysisto limitedsuccess. The differentiating feature is theinput impedance of the includethe effects of otherasymmetric modes of theclass IV. The in-vacuo loudspeaker.In this presentation the role of theacoustic coupling between modedescription of thetransducer's surface velocity will be improvedby adjacenttransducers in a loudspeakerarray will be examined.The acous- usingthree-dimensional mode shapes. The trial functionsdescribing the ticalinteraction between transducer elements is modeled.The impactof surfacepressure are modifiedas well. Changesin theimpedance charac- this interactionon beamformingis examined. teristicsfor thesymmetric modes due to thisimproved transducer descrip- tionwill be shown.The characteristicsof the nonsymmetric modal imped- 4:30 ances are comparedto those of the symmetricmodes as a function of dimensionlessmajor axis ka and dimensionlessseparation distance kd. 2pEA14. Variational principles derived for discontinuous Suitablemethods for combiningthese modal impedances into a totalra- electromagneticfields. G. A•kar Altay (Bo•aziqi Univ., Istanbul, diationimpedance for the transducerwill be presented.The effectof rela- Turkey) and M. Cengiz D/Skmeci (IstanbulTech. Universit-Teknik tive orientationof the transducerson the radiationimpedance is investi- Univ., P.K.9,Taksim, 80191 Istanbul,Turkey) gated.The resultswill be comparedto equivalentcircuit modelsand A unifiedprocedure based on a generalprinciple of physics(e.g., experimentaldata. [This work was sponsored by theOffice of NavalRe- Hamilton'sprinciple) together with Legendre's (or Fdedrichs's)transfor- search.] mationis proposedto systematicallyderive certain vadational principles
3300 J.Acoust. Soc. Am., Vol. 97, No. 5, Pt.2, May1995 129thMeeting: Acoustical Society ofAmerica 3300
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp for discontinuouselectromagnetic fields which are usefulto treatelectro- recorded which have those for time-harmonic motions and a dielectric magneticwaves and vibrations in dielectrics.The integraland differential regionwithin a vacuumor a perfectconductor, and they are shown to agree typesof variationalprinciples generate Maxwell's equations and the asso- with and to recoversome of earliervariational principles [e.g., M. C. ciatednatural boundary and jump conditionsas well as the initial condi- D/3kmeci,IEEE Trans. UFFC UFFC-35, 775-787 (1988); UFFC-37, tions,as theirEuler-Lagrange equations, for a regularfinite and bounded 369-385 (1990)and G. A. A•kar,J. Acoust.Soc. Am. 95, 3007(1994) and dielectricregion with or withouta fixed,internal surface of discontinuity. referencestherein]. [Work supported in partby The Scientificand Tech- Specialcases of the variationalprinciples, including a reciprocalone, are nicalResearch Council of Turkey.]
WEDNESDAY AFTERNOON, 31 MAY 1995 AUDITORIUM, 1:00 TO 4:00 P.M.
Session2pED
Education in Acoustics: Demonstrations in Acoustics
Sally G. Revoile, Chair Centerfor Auditoryand SpeechSciences, Gallaudet University, Washington, DC 20002
Chair's Introduction--l:00
Invited Papers
1:05
2pED1.How musicalinstruments make sound. ThomasD. Rossing(Phys. Dept., Northern Illinois Univ., DeKalb, IL 60115) Simpledemonstration experiments help us understand how bars, membranes, plates, and air columns vibrate and how they produce musicalsound. They alsohelp us understandthe physicsof vibrationsand waves.
1:20
2pED2.Analysis and synthesis of speech.Tom Tremain (U.S. Dept. of Defense,9800 Savage Rd., Fort George G. Meade,MD 20755-6000)
Speechproduced by individualaudience participants will be storedon a computer.Speech waveforms in thetime and frequency domainswill thenbe displayed by thecomputer. The speech will beplayed back in itsnatural form, and also after it hasbeen analyzed andsynthesized. Various transforms of thespeech will be implementedand played back. For example,the speech will be speededup andslowed down. The genderof the voicewill be changedby alteringthe pitchperiods. The speechwill be madeto seemas if the talkerhad a coldby changingthe voicingof the consonantsounds.
1:35
2pED3. A dynamic absorber and a side-branch resonatorfor vibration and noise control. M. G. Prasad,E. Zanone,and S. Abbattista(Noise and Vibr. Control Lab., Dept. of Mech.Eng., Stevens Inst. of Technol.,Castle Point on theHudson, Hoboken, NJ 07030)
This paperpresents two demonstrations.The first one dealswith controlof vibrationsof a motorunder unbalance excitation. A dynamicabsorber is usedto reducevibrations of themotor. The resonancephenomenon and mode shapes in vibratingsystems will be shown.The secondsystem is a finitelength duct with an acousticsource (speaker) at oneend. A Helmholtzresonator as a side-branch deviceis usedto reducethe noiseradiating from the open-endof the duct.Audible effectsdue to acousticresonances in the duct and side-branchresonator system will be presented.
1:50
2pED4,A lecturedemonstration of the cochlea. Rober•M. Keolian (NavalPostgraduate School, Dept. of Phys,,Code PH/Kn, Monterey,CA 93943)
Partof the mysteryof the cochlea,the organof hearingin mammals,is how it distinguishesdifferent frequencies from oneanother so well. Even thoughthe cochleais small,filled with fluid, and madeout of tissue,its frequencyselectivity corresponds to a quality factorQ whichis quite high--about 300. Part of the answerlies with an unusualtraveling wave that depositsthe energyof different frequenciesat differentpositions. This will be shownwith a lecturedemonstration that displaysthe physicsof this wave.
3301 d. Acoust. Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting: Acoustical Society of America 3301
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 2:05
2pED5. Demonstrationsof acousticresonant systems. JamesM. Sabatier,Richard Raspet, and BruceDenardo (Natl. Ctr. for PhysicalAcoust. and Dept. of Phys.and Astron., Univ. of Mississippi,University, MS 38677) The phenomenaof "sonicwind," viscousdrag, and high "Q" in resonantacoustic systems is demonstrated.The firsttwo are the well-knownChristmas tree balls and rotating cup demonstration. The thirdis a largeheavy tuning fork whichrings for a verylong time after being struck.
2:20-2:35 Break
2:35
2pED6. Demonstration of room acousticparameters using a digital multieffects processor. StevenM. Haas (Jaffe Holden ScarbroughAcoust. Inc., 114A WashingtonSt., Norwalk, CT 06854)
Digital multieffectsprocessors is a usefultool to studyand demonstrateroom acousticparameters. Live and prerecordedspeech andaudio program will be processedthrough a multieffectsdevice and reproduced through a pair of loudspeakers.The listenerswill be allowedto hearthe effect of varyinga numberof acousticparameters that occur in naturalspaces. These include: reverberation time, echoes,diffusion of sound,high frequencydecay rate, initial time delaygap, spaciousness,and depth.A brief explanationof each parameterwill be givenbefore its audibledemonstration. The meansin whichan architecturalacoustician designs an acousticspace with theseparameters in mind will alsobe discussed.
2:50
2pED7. 15 minutesof chaos. Murray S. Korman (Dept.of Phys.,U.S. NavalAced., Annapolis, MD 21402) and LawrenceA. Crum (AppliedPhysics Lab., Univ. of Washington,Seattle, WA 98105) Apparatus(both mechanical and electrical) will be presentedto illustratethe complexitiesof a certainnonlinear behavior termed as chaos.In this demonstration,you will seea "chaosman" (a storebought sticklike compound pendulum) oscillate with a very complexmotion. A simplependulum will be madeto oscillate(inverted) with the pivot at thebottom and the mass at thetop. An electriccircuit (modeling a nonlinearmechanical system) will be usedto demonstratechaotic behavior--which occurs when the systemis drivenwith sufficientamplitude at certainfrequencies.
3:05
2pED8. How a wind instrument makes a sound. Peter L. Hockje (Phys.Dept., Univ. of Northen•Iowa, Cedar Falls, IA 50614-0150)
Twodemonstrations illustrate the mechanism of soundproduction in musicalwind instruments. First, a "watertrumpet" inspired by A. H. Benadeproduces waves in a water-filledtrough. The waveaction is generatedat oneend of thetrough by a feedbackvalve whichregulates the inlet flow of wateraccording to theheight of thewater waves at thatsame end of thetrough. This is analogous to thegenerarios of soundin lip reedbrass instruments and cane reed woodwinds in whichthe flow of air throughthe reed valve is affectedby thepressure inside the instrument mouthpiece. The seconddemonstration again mimics the feedback mechanism of the reedwith a simpleelectronic device which allows a windinstrument to sound itself. The air in themouthpiece is excited by a small speakerwhich is drivenby an amplifiedsignal from a microphonesensing the pressure in themouthpiece. The playing frequency dependson theresonances of the instrument and corresponds to a normalnote of theinstrument. Thus the demonstrator can finger a scaleon the instrumentand the instrumentwill play along.
3:20
2pED9.Reverberant sound in one-,two-, and three-dimensional spaces. William J. Strongand David C. Copley(Dept. of Phys. and Astron., Brigham Young Univ., Provo, UT 84602)
Tha mathodof imageswas ugad to calculateimpulse responses for a large(30 mSd921mSd lg m) threedimensional apace, a large (30mX23 m) two-dimensionalspace, and a large(30 m) one-dimensionalspace. The reverberation time for these spaces was set to approximately1.5 s andall soundabsorption took place at thewalls. Similar impulse responses were calculated for smallrooms whose dimensionswere one-tenth those of thelarge rooms and whose reverberation times were smaller. A short(10-s) sample of singingwas recordedin anartechole chamber and then convolved with the various impulse responses. The resulting six reverberated samples of singingwere recorded binaurally on audio tape. Graphs of theimpulse responses and the taped examples will bepresented. (Although the tapedexamples will be presentedvia loudspeakers,they are best heard via earphones.}
3:35-4:00
AudienceParticipation with Exhibits
3302 J. Acoust.Soc. Am., Vol. 97, No.5, Pt.2, May1995 129thMeeting: Acoustical Society of America 3302
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp WEDNESDAY AFTERNOON, 31 MAY 1995 MEETING ROOM 2, 1:00 TO 4:45 P.M.
Session2pNS
Noise:Advances in Aircraft NoiseModeling and Monitoring
Sanford Fidell, Cochair BBN Systemsand Technologies,21120 VanowenStreet, Canoga Park, California 91303
Nancy S. Timmerman,Cochair Massport, 600 Control Tower,East Boston,Massachusetts 02128
Chair's Introduction--l:00
Invited Papers
1:05
2pNSI. Measuringaircraft noiseimpact in a low signal-to-noiseenvironment. NathanB. Higbic (LarsonDavis Systems, 13l MiddlesexTrpk., Burlington,MA 01803)
Theagreements negotiated for thenew Denver Airport present an interesting example of howlegal considerations can govern how noisemeasurements aremade. The agreements stipulate certain noise limits on communities surrounding the airport. These limits are expressedin aircraft Leq(24), and are placed at 102points, some over 15 miles away. There are financial penalties if any values are exceededfor a year.A signal-to-noisemeasurement problem resulted since modeled values of theaircraft Leq(24) were lower than measuredLeq(24) community noise. The problems that needed solving were detection and quantification of aircraft noise in low signal-to-noise,and assignment of each noise event to itssource. Arrays and other spatial techniques were proposed, but were too costlyand would not meet Type I measurementrequirements. A floating threshold was implemented so thatnoise events could be detectedfor anyambient condition. To date,all airportmonitoring systems have used a fixedthreshold since signal-to-noise is not a problem.The events are then correlated with the flight track data using a statisticalpattern recognition algorithm whose parameters are optimizedfor eachmonitor location.
1:25
2pNS2.Integrated noise model (INM) 5.0. JakeA. Plante (Analysisand Evaluation Branch, Office of Environmentand Energy, FederalAviation Administration, Washington, DC 20590) Theability to accuratelyassess and predict noise exposure is an increasinglyimportant factor in thedesign and implementation of airportand airspaceimprovements. To meet this challenge,the FederalAviation Administration (FAA) Office of Environmentand Energy(AEE) is undertakinga series of operationsresearch initiatives to improvethe modeling and other quantitative methods used to evaluateaviation noise impacts. A majoreffort in recentyears has been the redesignof the integratednoise model (INM 5.0) in Windows.While rewrittenin a differentcomputer language, the noisecalculation algorithms in 5.0 remainessentially the sameas V4.11,based on the SAE-AIR-1845methodology. There are, however, many technical enhancements to the computer code which providefaster mn timesand moreaccurate noise predictions. Among the enhancementsare (1) a noisecalculation module that is between1.5 and6 timesfaster depending on the studycase, (2) a newexposure fractioning algorithm for improvedaccuracy, (3) additionstothe aircraft database, (4)new metrics (e.g., Lmax, Leq•n), user-defined), (5) user-defined profile generation forthe study of noiseabatement landings and approaches, (6) a lateraltrack dispersion methodology, and (7) GIS analysiswith Census, CAD, NFDC, elevation,and ARTS radardata capabilities.
1:45
2pNS3.Statistical methods for automated1NM pathderivation. DavidA. Flynn (LarsonDavis Labs., 1681 W 820 N, Provo,UT 84601)
Flightpaths at an airportcan be viewedas samplesof a statisticaldistribution. An individualsample path x i , is describedby the positionas a functionof distancefrom the airport.The meanpaths of distribution(Xm) minimize •xi-(Xclosest), where the operator "-" is an approximationof the differencein groundnoise projection of two paths,and "m" is the desirednumber of meanpaths. Clusteranalysis methods can be usedto find this set of meanpaths: they will by definitionbe the optimalm pathsfor use in the 1NM in placeof the original samplepaths. These methods can reducehundreds of thousandsof radar monitoredpaths into a conciseset of INM tracks.Moreover, they do not suffer measurementanomalies that gate penetrationanalysis suffers.
2:05
2pNS4.Modeling aircraft departureprofile using ARTS radar data. PaulDunholter (MestreGreve Assoc., 280 NewportCtr. Dr., NewportBeach, CA 92660)
The currentmethod for the modelingof aircraftdeparture profiles is to usethe standarddeparture profiles contained in the INM noisemodel. The INM modelaccounts for the differentdeparture gradients based upon the flightdistance to the aircraft'sdestination. Aircraft flying a longerdistance are assumedto be heavierand as a result,would climb at a lower gradient.New techniquesinvolve usingthe actualflight profilesfrom the FAA's ARTS radar data. State-of-the-artairport noisemonitoring systems collect flight track
3303 J. Acoust. Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3303
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp data[Aircraft identification, Type of operation,and aircraft position (X. Y andZ)] fromthe ARTS data. This information can be processedto determinethe actual flight profiles for eachaimaft type as well asa rangeof profilesfor a specificaircraft. Using this technique,the departure profiles used in themodel account for notonly the departure distance, but also pilot techniques, the actual aircraftload as well asmeteorological conditions such as altitude, density, and wind speed. The resultis thatthe modeling of aircraft departureflight profiles are based upon actual data specific to theflights and conditions at theairport under study.
2:25
2pNS5. Use of flight track information to resolveindividual and community-wideaircraft noise concerns. Karen L. Robertson(Dallas/Fort Worth Int'l. Airport.P.O. Drawer 619428, DFW Airport,TX 75261-9428) Technologicaladvances in airportnoise monitoring systems have provided the "missing link" of dataneeded to managean airport noiseoffice effectively. The addition of aircraftflight track and altitude information has given airport proprietors the necessary tools to understand,if not alleviate, certain community concerns regarding aircraft noise and overflights. Airport neighbors often contact the localairport or FAA officewhen an aircraftoperation is annoying.The annoyance may be a resultof one.or many,concerns ranging from noiseto aircraftflight patternsto overall safety.Once concernsare voiced,airport neighbors want immediateinformation regardingthe annoying event, followed by theever-allusive "corrective action." Specific examples of howthe new generation airport noisemonitoring and flight trackingsystems can respondto communityor individualconcerns will be demonstratedin an interactive format.followed by innovative.intriguing uses for the system.Information from thesesystems can surpriseeven the mostknowl- edgeableairspace analyst or airport noiseofficial.
2:45
2pNS6.Wide area modelingof en routeaircraft noise. NicolaasReddingius iBBN Syst.and Technol., 21120 Van Owen St.. CanogaPark. CA 91304) and Michael Ebersole tNationalPark Service)
Mostaircraft noise modeling methods have been so carefully focused on airport-based policies and analyses that they are awkward touse for otherpurposes. For example, standard noise modeling software is of limitedutility for characterizing enroute noise exposure or assessingthe potential impacts on nonurban populations. The National Park Service has developed alternative methods for modeling aircraftnoise and its impactsin outdoorrecreational settings. Software created to supportPublic Law 100-91analyses permits users to performobserver-based (rather than source-based) aircraft noise analyses: m considerthe maskingprovided by localizedsources when modeling norseimpacts over areasof tens of thousandsof squarekilometers; to take terrain relief into consideration;and m presentresults in the form of map layersfor a geographicinformation system.
3:05-3:15 Break
ContributedPapers
3:15 numberof operations)by examiningeach of the threemetrics DNL, SEL. andTA. The noiseimpacts are comparedand the bestuse of the informa- 2pNS7. Applicationsof Boston-Logan'snoise monitoring system. tion is discussed. Nancy S. Timmerman {Massport,600 Control Tower, E. Boston,MA 02128-2042) 3:45
Boston'sLogan InternationalAirport has an advancednoise monitor- 2pNS9.Classification of noiseevents as aircraft overflightsby means ing systemconsisting of noise,aircraft track. weather, and land useinfor- of one-thirdoctave band algorithms. Matthew Sheddon •BBN Syst. mation.The systemhas been used to supportINM 5.0 validationefforts, to andTechnol.. 21120 Van OwenSt., CanogaPark, CA 91304) improveINM trackdefinitions, to assistin assessingaircraft departure procedures.and m isolatethe typesof aircraftaffecting various commu- A set of algorithmsfor real time classificationof noiseevents as low nities.Examples of the newerapplications pursued will be presented. altitudemilitary aircraft overflights was developed for usein a personal noisemonitoring system. The classificationalgorithms, which are applied to polynomialcurve fits to time seriesof soundpressure level measure- 3:30 mentsrather than to rawdata, operate primarily on thetemporal symmetry 2pNS8. A comparisonof different aircraft noise metrics for large, and relative rates of increase and decrease of sound levels in different medium,and small airports. MelissaBurn, Eric Stusnick.and Gary one-thirdoctave bands. Correct classification performance and misclassi~ Ehrlich (WyleLabs., 2001 .lefferson Davis Hwy.. Ste.701. Arlington, VA ficationerrors vary with disjunctive decision rules applied to the outputs of 22202) the algorithms.[Work supportedin part by the U.S. Air ForceNSBIT program.] A wide varietyof metricsare availableto representand evaluate noise impactsfrom aircraftoperations. Two of thesehave gainedwide accep- 4:00 tanceand are usedextensively m norsestudies and mitigation programs 2pNS10.Effects of military aircraft noiseon residentialproperty throughoutthe UnitedStates: Day nightaverage sound level (DNL) and soundexposure level (SEL). A third metric,time aboveITA), is not often saleprices near Langley Air ForceBase. SanfordFidell (BBNSyst. andTechnol., 21120 Van OwenSt., CanogaPark, CA 91303), Barbara usedbut is very oftenrequested by commumtymembers who believeit TabachnicktCalifornia State Univ., Northridge), LauraSilvati tBBN will representtheir noise problem more convincingly than the others. Each Syst and Technol.), and Brenda Cook •U.S. Air Force Air Combat metricdiffers significantly from the othersboth in the way it represents Command) noiseimpact and in way themeasure is bestemployed. For example,since DNL accounts for the loudness of individual events and the number of An empirical,market-based method was developed m assesswhether operations,an equivalentDNL value can resultfrom a few very loud militaryaircraft noise exposure has affected residential property values in overflightsor a largenumber of quieterones. DNL is considereduseful in thevicinity of LangleyAir ForceBase over the last two decades. Multiple predictingthe averageresponse of communitiesbut not of individuals.The regressionmodels that accounted for thebulk of thevariance •n property authorsevaluated the no•seimpact for differentsized airports tbased on saleprices were developed and validated for independentsamples drawn
3304 J.Acoust. Soc. Am., Vol. 97, No. 5, Pt.2, May1995 129thMeeting: Acoustical Society of America 3304
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp from areasof Hampton,VA exposedto levelsof military aircraftnoise equivalentlevel (CNEL), the day-evening-nightweighted 24-h average lowerthan DNL=60 dB. The predictiveperformance of thesemodels was levelspecified for Californiaairports. The 148-dayaverage CNEL was69 indistinguishablein areas of Hamptonexposed to militaryaimraft noise in dB. In oneweek CNEL variedfrom 58 dB on Sundayto 75 dB onTuesday. excessof DNL--65 dB. Mapsconstructed by geo-codingproperty sale Suchnoise variability is beinginvestigated in relationto futuremovement locationspermitted spatial comparisons of propertyvalues with aircraft of Navyaircraft from Miramar to NAS Lemoore,and Marine aircraft from noiseexposure contours. These maps confirmed the independenceof the MCAS El Toro to Miramar.Also beinghere reported for 7084 Miramar spatialdistributions of propertyvalues and aircraft noise contours in the Roadare the A-weighted sound exposure levels (ASEL) in excessof 100 vicinityof LangleyAir ForceBase. dB; the greatestthus far is 116dB.
4:15 4:30
2pNSll. Six months of continuousmeasurement of one-hour average 2pNSI2. The SEL noise reduction provided by barriers to residences sound levels, one mile sidewise from NAS Miramar, San Diego. locatednear runwayends. MarcioAvillez (WyleLabs., 2001 Jefferson RobertW. Young (1696 Los AltosRd., SanDiego, CA 92109-132l) Davis Hwy., Ste. 701, Arlington,VA 22202)
From 18 July 1994to 17 December1994, l-h averagesound level was The T.F. Green StateAirport in Warwick, RhodeIsland, has a noise measuredcontinuously by ComputerEngineering Ltd. model493 integrat- barrierintended to reducenoise at residenceson one sideof Runway05, ingsound level meter feeding model 238A secondary processor. The time- near the start of the takeoff roll. Measurements were conducted to evaluate mean-squareaverage level printed automatically on thehour, and recorded theattenuation provided by thebarrier. TMs wasaccomplished by selecting in an RS232Cmemory for lateranalysis, is thatduring the hour preceeding pairsof measurementpositions that were located on oppositesides of the the hourprinted. The site of noisemonitoring is the roof 7084 Miramar runwayand equidistantfrom the centerlineof the runway.The measure- Road, San Diego, abouta mile sidewisenorth of Runway6L-24R, NAS mentresults indicate that barriers can significantlyreduce SEL of depart- Miramar.After adjustmentsto removesteady ventilating and compressor ing aircraft,and consequently the DNL, at residenceslocated near the end noise,aircraft noise was tabulatedfor each day as communitynoise of a runway.
WEDNESDAY AFTERNOON, 31 MAY 1995 MEETING ROOMS 12, 13, 14, 1:00 TO 4:50 P.M.
Session2pSA
Structural Acousticsand Vibration: Wayne Reader Memorial Session
Walter M. Madigosky,Cochair CarderockDivision, Naval SurfaceWarfare Center, 10901 New HampshireAvenue, White Oak, Silver Spring, Maryland 20903
Gerald Casteiluci, Cochair VectorResearch Company, Inc., 2101 East JeffersonStreet, Suite 701, Rockville,Maryland 20852
Introduction--1:00by MauriceSevik CardcrockDivision Naval SurfaceWarfare Center, Bethesda, Maryland 20084
Invited Papers
1:05
2pSAI, The measurementof target strength of complex underwater structures---Theearly years. Jan M. Niemiee (Naval SurfaceWarfare Ctr., CardcrockDiv., Bethesda,MD 20084-5000)
By theearly 1970's,few measurementsof targetstrength of largescale underwater structures had been made. Novel measurement techniquesto controlthe range, depth, and aspect angle of the underwatertarget had to be developed.Unique instrumentation had to be devisedto measurethe incidentsound level at the targetand to reliablyrecord the scatteredsound wave on a pingby ping basis withoutinterrupting the rotatingtarget. Dr. WayneReader lead a groupof scientistsand engineers who successfullyovercame many of thesedifficulties and measured the targetstrength of a largescale model of a complexstructure known as KAMLOOPS.In addition to providingthe leadershipfor the resolutionof manytechnical problems, Wayne Reader developed a uniquemethod to calibratethe scatteringmeasurements by usingthe doubly curved surface of theKAMLOOPS dome as a standardtarget. Many of themeasurement techniquespioneered by Wayneare still in use today.This talk outlinesthe aspectsof a modeltarget strength measurement and illustratessome of the manycontributions that Waynemade to this field of science.
1:25
20SA2,Sonar baffles, RonaldP. Radlinski (NavalUndersea Warfare Ctr., DetachmentNew London,New London,CT 06320)
Acousticdecoupling baffles are often usedto minimizenoise contamination at hydrophoneand transducerarrays. To maintain sensitivitynear the nominallypressure release surface of the baffle,hydrophones can be placedat an odd multipleof a quarter wavelengthfrom the baffleor neara heavysignal conditioning plate inserted between the hydrophones and the baffle. In eithercase, coherentinterference between the incidentwave and the wave reflectedfrom the baffle limits the bandwidthof high sensitivity.Wayne Readerreasoned that by insertinga broadbandabsorber between the hydrophonesand the decouplingbaffle, a smootherhydrophone
3305 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3305
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp responsecould be attainedof potentiallyless weight with relativelysmall loss in sensitivity.The talk describesthe useof gradual transitionabsorbers developed by Waynefor sonarapplications and his interactionswith the authorto combinethese materials with broadbandde. couplers such as arraysof complianttubes. His carefuland thoughtfulapproach to the theoreticaland experimental aspectsof acousticand materialresearch was inspirationaland we misshis insight,advice, and encouragement.
1:45
2pSA3.Wayne T. Reader:The VeetorResearch Company years, 1988-1994. C. WarrenVest (VectorRes. Co., Inc., Ste.700, 2101 E. JeffersonSt., Rockville,MD 20852)
After 30 yearsof distinguishedgovernment service Dr. WayneT. Readerretired in 1988and joined Vector Research Co., Inc. as principalresearch scientist. He continuedhis Navy-sponsored anechoic materials research program. He recruiteda talentedresearch anddevelopment team and established a state-of-the-aR dynamic material evaluation laboratory. He developedunique experimental proceduresfor evaluatingstatic and dynamicproperties of viscoelasticmaterials, an extensivematerial properties database, and analyticalcomputer programs to predictacoustic performance of layeredmedia including anechoic lining systems.He continuedto seekeconomical solutions to acousticquieting and won a competitiveNavy procurementto designand installan innovativelining systemto a largeanechoic test tank. While continuing his work with passivevoided polymers, he beganexploring the advantagesof compositescontaining discrete and distributedpiezoelectric particles in a polyurethanemedium. In additionto his technicalwork, WayneReader established a working environment which met notonly his interestsbut alsothe company's and the Navy's as well. He attractedand mentored several young scientists who continueto work in thisfield.
2:05
2pSA4.The developmentof 1-3 piezocompositematerials for large-areaactuator applications. Robert Y. Ting (NavalRes. Lab., UnderwaterSound Reference Detachment, P.O. Box 568337, Orlando,FL 32856-8337}
One of the technicalsubjects to which the late Dr. Wayne Readermade a significantcontribution in recentyears was the developmentof 1-3 piezoelectriccomposite materials, which consistof thin ceramicrods alignedand embeddedin a polymeric matrix.The combinationof goodpiezoelectric properties and the potentialof low-costmanufacturing for largearea coverage makes thisnew class of compositematerials attractive for applicationas large area actuators in vibrationcontrol. Some of Dr. Reader'swork will be reviewed,and the mostrecent development of new 1-3 piezocompositeswill he discussed.Special new fabricationmethods andthe resulting material will be introduced.Acoustical propetxies of thesenew samples have been evaluated as a functionof pressure andtemperature and some of the resultswill he reportedin thispresentation.
2:25
2pSAS. History and status of working group S2-79 on the characterizationof the dynamic properties of v•scoelastic polymers. BruceHartmann (PolymerSci. Group,Naval SurfaceWarfare Ctr., 10901New HampshireAve., Silver Spring,MD 20903-5640)
Recognizinga long-standingneed for standardmaterials to calibrateacoustic measurement equipment, Wayne Reader initiated a WorkingGroup with the title "Characterizationof the DynamicProperties of ViscoelasticPolymers." The WorkingGroup was o•ganizedunder Standards Committee S2 of the AcousticalSociety of Americaand was giventhe designationS2-79. The desirable qualitiesfor the materialswere: Ready availability, wide rangeof acousticproperties, stable with time, reproduciblefrom lot to lot, andthermorhcologically simple. He drewGroup members from government, private industry, and universities, both in thiscountry and abroad.Under his leadership,the Working Group progressed to the pointthat its work is nearlycomplete. This presentationwill give an overviewof the resultsfrom variouslaboratories on the most promisingcandidates. Emphasis will he given to a high loss polyurethane,for whichthe mostdata is available.In contrast,data for a low losspolyurethane will be presentedto illustratethe reasons it was eliminated as a standard.
2pSA6.A techniquefor measuringthe reflectivityof panelsat low frequenciesand high obliqueangles. J.J. Dlubacand R. J. l•igan (Code721, SignaturesDirectorate, Cardcrock Div. of the Naval SurfaceWarfare Ctr., Bethesda,MD 20084-5000)
Conventionalshort-pulse techniques for measuringtbe reflectivityof acousticpatrol; requlr* that the r•fiectoclam] incident wawa heseparated in timeso that their ratio can he established. This technique is limitedto moderateangles of incidence,since at highangles the directand reflectedwaves overlap. An interferencemethod is investigatedas a way of makingreflectivity measurements at high obliqueangles. The total field (incident and reflected) near an oblique panel is measuredrelative to theincident field without the panel. The totalfield, which depends on frequencyand angle of incidenceas well as the panelmaterial, is thenexamined and manipulated to extractinformation on the reflectedwave. The techniqueis demonstratedwith data reducedon steelplates.
3:05-3:20 Break
3306 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3308
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp ContributedPapers
4:05
2pSA7. The design and developmentof an anechoiclining system 2pSA10. The loss factor of beams with thick constrainedlayers. for the acoustic test facility at NUWC Newport. N. Scott Emery. Joel Garrelick (CambridgeAcoust. Assoc., Inc., 200 BostonAve., LoisPcfia, Shami Satyapal, Kin Ng, andDavid Sauter (VectorRes. Co., Medford,MA 02155) Inc., Ste. 700, 2101 E. JeffersonSt., Rockville,MD 20852) A constrainedlayer beam, consisting of a basebeam, viscoelastic layer, During his yearsat VectorResearch Company, Inc., Dr. WayneT. and cover plate, is analyzedwith each layer modeledusing the two- Readerapplied his extensive knowledge and experience in absorptiveand dimensionalequations of viseoelasticity.The (three) layers are "cas- decouplingcoatings to the designand developmentof anechoiclining caded,"enforcing appropriate equations of continuity.A shapefactor is systemsfor largeacoustic test tanks. The resultof Dr. Reader'sefforts was invoked to account for the effect of the beam's finite width on the dilata- the awardof a competitiveNavy procurementto Vectorto designand tionalwave speed of theconstrained layer. Composite loss factors are tirst installa broadfrequency (1 to 100 kHz) anechoiclining system in the definedsolely for thefreely propagating (modified) flexural wave-number acoustictest facility (ATF) and NUWC Newport.Based on Dr. Reader's componentof the responseand then in termsof the overalldrive point designsand concepts, a prototypeanechoic lining system for theATF and responseof tbe beamto a mid-spanload. At low frequenciesresults are NUWC Newportwas tested successfully and the full systemwill be in- comparedto valuesobtained from Kerwin's [1959] classic thin layer stalledin the Springof 1995.Background on the designand development model.At theother end, high frequency asymptotic limits are obtained by of the liningsystem and data from prototype testing will be presented. viewingIhe constrainedlayer as beingsemi-infinite and/or "fuzzy." Fi- nally,predictions are comparedto measurementsperformed on a steel- Nitrile-steelbeam [Junget et al., 1986]. 3:35
2pSAS. Basic model for acousticreflection and absorptionfrom multilayered underwater, sound-attenuating composites, Donald
Brill (U.S. Naval Acad., Phys. Dept., Annapolis,MD 21402), 4:20 ArmandoSantiago (Naval Surface Warfare Ctr., Annapolis, MD 21402), and GuillermoGaunaurd (Naval SurfaceWarfare Cu-., White Oak, MD 2pSAll. Resultsof recent developmentto measureand analyze the 20903-5640) dynamic propertiesof materials. Ahid Nashif (RoushAnatrol, 935 BeneciaAve., Sunnyvale, CA 94086) To reducebackscattered acoustic echoes from submerged elastic struc- tures,these are routinely covered with viscoelastic{i.e, sound-absorbing) Althoughthe vibratingbeam technique has been widely used and dem- compositemultilayers. This old and well-studiedarea is revisitedand a onstratedto be an effectivetechnique for measuringthe dynamic proper- basic,simple, analytical model to predicthow thesecomposites behave ties of materials,it has its own limitations.This is becausethe present whentested is presented.The multilayercan haveN layersof homoge- analysisuses the fourth-orderbeam equations which do not adequately neons(or inhomogeneous)materials with differentelastic/viseoelastic handlethe boundaryconditions of the testspecimens especially for the properties,all bondedto eachother, and the whole,to a backing(metal) fundamental mode of vibration. Becauseof that, measurementson the first plate. The structureis fluid-loadedand externallyexcited with plane, and sometimes the second modes of vibration have been omitted which monochromaticsound waves. We havedeveloped a "propagatormatrix" limitsthe frequencyrange where measurements could be made.To over- approachthat yieldsthe reflected,transmitted, and absorbedwaves from comesuch limitations, a new approachusing finite elementanalysis has the structureas a productof the N transfermatrices of the layers.The beendeveloped to computethe dynamic properties of materialsfor several approachis computerizedand usedto evaluateand plot the reflectivity modesof vibration,including the lowerones. This analysisis suitedfor and/orabsorptivity of thestructure as a functionof frequencyfor pertinent eitherextensional or sheardeformation, depending on the geometryof the (oftencomplex) values of thelayers' material parameters and thicknesses. specimen.Results of usingthis analysis to computethe dynamic properties The predictionsare experimentallyverified for selectedtest cases (i.e., of the variousproposed materials for the S2WG79standard will be pre- N= 2,3), and the enhancementof the echo-reductionplots at the resonance sented and discussed. frequenciesof the layersis noted.Additional complexities can be handled in a straightforwardfashion. [Work partially supported by theIL-IR Pro- gramof the CDNSWC.]
4:35 3:50 2pSAI2. Flow-inducedself-noise on a sphericalsensor, Andrew R. 2pSA9. Dynamic mechanicalanalysis ASTM/ISO. JamesS. Peraro Jonesand Gerald C. Lauchlc (GraduateProgram in Acoust.and Appl. {HimontUSA, 912Appleton Rd, Elkton,MD 21921) Res.Lab., Penn State Univ., P.O. Box 30, StateCollege, PA 16804)
Dynamicmechanical analysis (DMA} is usedto characterizethe be- An experimentaleffort to characterizethe low Reynoldsnumber flow- haviorof a varietyof materials.The developmentof the methodologyfor inducedself-noise on a sphericallyshaped inertial sensor operating under- conductingthese tests is the responsibilityof AS'I'M D20.10.15 on dy- wateris described.The transduceris a smallgeophone encased in a sphere, namicmechanical properties. Similar activities are conducted in ISO under 76.2 mm in diameter.The sphereitself is cast from a 4:1 by volumeof the jurisdictionof subcommitte#2. The test methodsbeing developed polystyrenemicroballons and epoxyresin, which yields a slightlynega- covera broadrange of responses(temperature, frequency, and time) as tively buoyantbluff body that is capableof sensingweak fluctuationsin well asstress states (i.e., tensile, bending, shear, and compression). Instru- velocitysuch as thoseresulting from acousticdisturbances. When sucha mentshave been developed which have greatlysimplified the measure- sensoris usedin oceanenvironments, a spuriousself-noise signal often- mentof dynamicmechanical properties. The use of advancedcomputers timesexists due to low velocitycurrents. The researchdescribed in this and microprocessorsand improvedcomputer programs, to properlydigest paperquantifies this flow-induced noise signal as a functionof the sphere this information,have increasedthe demand for more sophisticatedtest diameterReynolds number (O 3307 J. Acoust.Soc. Am., Vol.97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3307 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp WEDNESDAY AFTERNOON, 31 MAY 1995 GRAND BALLROOM SOUTH, 1:15 TO 5:00 P.M. Session2pSC SpeechCommunication: Cross-Modal Integration and SpeechPerception Lynne E. Bernstein,Cochair Centerfor Auditoryand SpeechSciences, Gallaudet University,Washington, DC 20002 Kenneth W. Grant, Coehair WalterReed Army Medical Center,Army Audiology and SpeechCenter, Washington, DC 20307-5001 Chair's lntroduction•l:15 Invited Papers 1:25 2pSCl. Speechreadingaids basedon automaticspeech recognition: Prospects for the automaticgeneration of cued speech. L. D. Braida,R. M. Uchanski,and L. A. Delhome (Res.Lab. of Electron.,MIT, Cambridge,MA 02139) Currentprogress in the developmentof automaticspeech recognition (ASR) systemsmay soonpermit discrete symbolic speechreadingsupplements to be derivedfrom the speechsignal. Such supplements could be similarto thoseused in manualcued speech,in whichthe talker uses discrete hand positions and shapes to providedistinctions between constanls and vowels that are often confusedin speechreading.Highly trained receivers of manualcued speech can achieve nearly perfect reception of everydayconnected speechmaterials at normalspeaking rates through the visualsense alone. To understandthe accuracythat might be achievedwith automaticallygenerated cues, we measuredhow well trainedspectrogram readers and an automaticspeech recognizer could assign cuesfor variouscue systems.A modelof audiovisualintegration was then appliedto thesemeasurements and data on human recognitionof consonantand vowel segments via speechreadingwas published. This analysissuggests that with cuesderived from currentrecognizers, consonant and vowelsegments can be receivedwith accuraciesin excessof 80%, roughlyequivalent to the segmentreception accuracy required to accountfor observedlevels of manualcued speech reception. To provideguidance for the developmentof automaticcueing systems, we describetechniques for determiningoptimum cue groupsfor a givenrecognizer and speechreader,and estimate the cueingperformance that mightbe achievedif the performanceof currentrecognizers were improved. 1:55 2pSC2. Measuresof auditory-visualinlegration. KenW. Grant,John L. Clay,and Brian E. Walden (WalterReed Army Med. Ctr., Army Audinl.and SpeechCtr., Washington,DC 20307-5001) The easiestand most effectiveway to improvespeech recognition for hearing-impairedindividuals, or for normal-heating individualslistening in noisyor reverberantenvironments, is to havethem watch the talker'sface. Auditory-visual (AV) speech recognitionhas been shown consistently to be betterthan either hearing alone or speechreadingalone for all butthe mostprofoundly hearing-impairedindividuals. When AV recognitionis lessthan perfect, several factors need to he considered.The mostobvious of theseare poor auditory (A) andpoor visual (V) speechrecognition skills. However, even when differences in unimodalskill levels are takeninto account,differences among individual AV recognitionscores persist. At leastpart of theseindividual differences may he attributableto differingabilities to integrateA andV cues.Unfortunately, there is no widelyaceepted measure of AV integrationability. Recentmodels of AV integrationoffer a quantitativemeans for estimatingindividual integration abilities for phonemerecognition. In thisstudy, we compareseveral possible integration measures, along with modelpredictions, using both congruent and diserepant AV phonemeand sentence recognition tasks. The focusof thistalk will addressthe needfor independentmeasures of AV integrationfor individualsubjects. [Work supported by NIH GrantDC00792.] 2:15 2pSC3.Perceiving talking faces. DominicW. Massaroand Michael M. Cohen (Dept.of Psychol.,Univ. of California.Santa Cruz, Santa Cruz, CA 95064) Speechperception has been studied extensively in thelast decades. It hasbeen learned that people use many sources of information in perceivingand understanding speech. This talk focuseson theimportant contribution of visibleinformation given in thetalker's face in face-to-facecommunication. This visible speechis particularlyhelpful when the auditoryspeech is degradeddue to noise, bandwidthfiltering, or hearingimpairment. Although the influenceof visiblespeech is substantialwhen auditory speech is degraded, visiblespeech also contributes to performanceeven when paired with intelligiblespeech sounds. The importanceof visiblespeech is mostdirocfiy observed when conflicting visible speech is presentedwith intelligibleauditory speech. These studies use a synthetic talkingface to achievecontrol over the visible speech and to studythose visible aspects that are informative. The talking head can be heard,communicates paralinguistic as well as linguisticinformation, and is controlledby a text-to-speechsystem. A fuzzylogical modelof perception(FLMP) has been shown to providean accurate description of how people evaluate and integrate audible and visiblespeech in a broadrange of experimentalstudies. Demonstrations of the talking head and various psychological phenomena will be provided.[Work supported by NIDCD.] 3308 J. Acoust.Soc. Am., Vol. 97, No. 5, •. 2, May 1995 129thMeeting: Acoustical Sociely of America 3308 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 2:45-3:00 Break 3:00 2pSC4.A neural basisfor the synthesisof sound,sight, and touch. BarryE. Stein (Dept.NeurobioL & Anat. BowmanGray Schoolof Medicine,Wake ForestUniv., Winston-Salem,NC 27157-1010) That visualcues affect speech perception has been known for sometime, but is only onepart of the muchbroader phenomenon of cross-modalintegration. This fundamentalchardcteristic of the CNS hasa profoundinfluence on perceptionand behavior and is evidentnot only in speechperception, but in the facilitateddetection, identification, and reaction to combinationsof concordantcues fromdifferent modalities, and in thestriking perceptual anomalies that can occur when these cues are discordant. Understanding the mechanismsby whichthese functions are achievedrequires a fundamentalknowledge of the neuralbases of multisensoryintegration; specifically,the circuitsinvolved and the principlesby which such "multisensory"neurons synthesize their convergentsensory information.Perhaps the bestknown site of multisensoryconvergence is the superiorcolliculus, a midbrainstructure involved in attentiveand orientationfunctions. The spatial,temporal, and receptivefield characteristicsof its constituentmultisensory neurons serveas an excellent model for understandingthe neural principles of multisensoryintegration throughout the CNS andfor predicting over behavior.It will be thesemultisensory circuits, the neural ptinciples by whichthey affect multisensory integration, and the impact of this integrationon over behaviorwhich will be emphasizedin thisdiscussion. 3:35 2pSC5.Cross-modal perception: Similarities and communalities.Lawrence E. Marks (JohnB. PierceLab. and Yale Univ., 290 CongressAve., New Haven,CT 06519) Cross-modalperception encompasses two distinctdomains. One domainconsists of thoseobjects, events, or environmental conditions(e.g., phoneroes, shapes of objects,locations in spaceor time) aboutwhich different sensory modalities can provide commoninformation; the other domain consists of dimensionsor qualitiesof perceptualexperience in differentmodalities that bear a perceptualsimilarity that itself need not reflect any communality in theenvironment (e.g., between greater auditory pitch and greater visualbrightness). Cross-modal relations pervade perception, and they are readilydetermined through several psychophysical para- digms,including measures of perceptualequivalence between stimuli presented to differentmodalifes (cross-modal matches); mea- suresof cross-modalsimilarity, assessed by multidimensionalscaling; and measures of cross-modalinteractions in responsespeed and accuracyduring stimulus classification. Although many cross-modal relations are grounded in perceptualsimilarities or environmental communalities,interactions in the processingof stimulipresented to differentsenses can readilybe modulatedby language,and can alsodepend on semanticrecoding. [Work supported by NIH GrantDC00271.] 4:05 2pSC6.Unisensory and multisensoryconvergence in a phonetotopicregister. RobertE. Remez (Dept.of Psychol.,Barnard College,3009 Broadway,New York,NY 10027) Descriptivestudies have noted that speech perception is inelu•tablymultisensory if the listener can hear and see the talker. In such cases,the resolutionof linguisticattributes occurs by combiningauditory and visual inflow rather than by phoneticanalyses in each modalitybefore convergence. Because subjects readily acquire onanticipated proficiency in haptieand auditoryintegration, some researchershave conceptualized speech perception as a multisensorymeans of detectinga talker'sphonetic production, independent of memorizedsensory prototypes. These findings have motivated a definition of theproblem of sensoryconvergence in terms that are literallymultisensory: How do auditory and visual and haptic afferents coalesce? Recent studies of perceptualorganization in a speech modepresent a contrastingview, based on a phenomenonof onimodal convergence in speech perception. In thisresearch employing tonalanalogs of speechsignals, phonetic perception occurs if auditoryconstituents cohere. Failure of convergencein this empirical paradigmis equalto failureof phoneticperception. Togetbe•, Ibese studies suggest that integrationof sensoryattributes in speech perceptionis equivalentacross changes in domain,from uni- to multisensory,and wmxants an accountof convergencethat is general overchanges in thescale of thesensory projection. [Work suppoRed by NIDCD.] 4:35-5:00 DISCUSSION 3309 J. Acoust.Soc. Am., Vol. 97. No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3309 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp WEDNESDAY AFTERNOON, 31 MAY 1995 MEETING ROOMS 10, 11, 1:15 TO 5:00 P.M. Session2pSP SignalProcessing in Acoustics:Wavelet Analysis Techniques and ApplicationsH David I. Havelock, Chair National Research Council, IMS/ASP, M36 Montreal Road, Ottawa, Ontario K1A OR6, Canada Invited Papers 1:15 2pSPI.A waveletauditory model and noise suppression. Anthony Teolis (NavalRes. Lab., 4555 Overlook Ave., S.W., Bldg. 210. Washington,DC 20375-5000) Basedon a waveletauditory model (WAM) of the mammalianauditory system. discrete time-scale representations of acoustic signalswhich are inherently robust to "noise"emerge. The model consists of thetwo main processes of (i) a "continuous"wavelet transformwith a causalanalyzing wavelet determined by a "shark-fin"-shapedfrequency response (cooblear filter), and (ii) a specific andsignal-dependent sampling of the wavelettransform. In generalthe proteinof samplesin the waveletdomain is irregularand determinedat lowerfrequencies by activityat higherfrequencies. By analyzingthe modelin termsof the theoryof mathematical frames,it is shownthat acousticsignals may be fully recoveredfrom their WAM representationthrough iterative reconstruction algorithms.Noise is thoughtof asthat portion of an acousticsignal which is "incoherent"with respect to theunderlying WAM frame functions.Because coherent energy is highlylocalized and incoherent (noise) energy is necessarilyscattered in thetime-scale plane by theWAM framerepresentation, wavelet shrinkage techniques provide powerful algorithms for noisesuppression. Several numerical examplesof the noisesuppression abilities of thesealgorithms are presented in the paper. 1:45 2pSP2.Adaptive waveletcollocation methods and wave propagation. Wei Cai (Dept. of Math., Univ. of California,Santa Barbara,CA 93106) An adaptivewavelet eollocation method for the initial valueboundary problem of nonlinearPDE's is studied.The collocation methodis basedon a cubicspline wavelet decomposition forthe $obolev space Ho•(l}, where I is a boundedinterval. Based on a special"point-wise orthogonality" of thewavelet basis functions, a fast discrete wavelet transform (DWT) is constructed.This DWT transformwill mapdiscrete samples of a functionto its waveletexpansion coefficients in O(N logN) operations.The issue of efficient data structurefor the waveletcollocation methods will also be discussed.Numerical results for variousPDE's includingwave propagationwill be presented. ContributedPapers 2:15 seafloor.These transfer functions were then expanded onto damped com- plex exponentialwavelet bases. In this casea discreteimplementation of 2pSP3. Exploratory wavelet transform analysisof seismoacoustic the continuouswavelet wansformwas used.This lechniqueallowed the data, RandallW. Smith,Steven A. Stotts,and Robert A. Koch (Appl. signalsbe decomposedinto distinctmodes by localizingsignal component Res. Labs., Univ. of Texas,P.O. Box 8029, Austin,TX 78713-8029) energiesin time and frequency.Modal featureswere then analyzedfor The one-dimensionalcontinuous wavelet transformis applied to the cluesto the physicalmakeup of the seafloor.Techniques were developed analysisof seismoaeoustiedata. The dataconsist of receivedsignals, due for extractingmodal features from the waveletsignal expansions. These to an impulsivesource, measured by a triaxial seismometer.The wavelet modal featuresinclude modal densities,center frequencies. bandwidths. transformprovides a time-frequencydecomIm•ition of the signal.which in duration,and mostimportantly. decay rates. The modalfeatures were ana- turn yields informationabout dispersion and arrival times of the various lyzedfor cluesto the physicalrnal•up of the seabottom. Available infor- propagationmodes. The primarygoal of theanalysis is to exploremethods mationwas exploited to invertfor internalsediment structure. particularly for extractinginformation from thetime-frequency representation. The use sedimentdensity and the presenceof trappedbubbles. Feature-based bot- of the wavelettransform will be complementedby modelingeffort. In tom mapswere generated allowing classification of the seafloor.[Work particular,the differentmodes of propagation.estimating geoacoustic pa- supportedby NRI•SSC underthe MTEDS program.] rameters,and localizingthe sourcewill be identifiedand analyzed. 2:45 2pSPS. Signal de,noising using matching pursuits. Wade Trappe 2pSP4. Wavelet applications to bottom sediment classification- (Appl. Res. Labs.and Dept. of Math., Univ. of Texas.P.O. Box 8029, RussellPfiebe, Nicholas E Chotiros (Appl. Res.Labs., Univ. of Texas, Austin,TX 78713-8029) Austin,TX 78713-8029), Donald1. Walter,and DouglasN. Lambert (NavalRes. Lab., $tennis Space Center. MS 39529) This paperwill examinein brevitythe matchingpursuit algorithm pro• by Mallatand Zhang which yields an adaptivesignal decompo- Waveletsignal decomposition techniques applied to fathometerechoes sitionthat may be usedto derivea phaseplane representation of a signal. were used for seafloor classification. Fathometer echoes were deconvolved Matchingpursuits is closelyrelated to waveletanalysis and may be con- with their sourcesignals to yield transferfunctions representative of the sidereda supersetof waveletmultiresolution analysis. A methodologyfor 3310 J. Acoust.Sec. Am., Vol.97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Sociely of America 3310 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp coherentfeature extraction, or denoising,using matching pursuits will be 4:00 developedand explained. Acoustic signals derived from speech and music will be examined.Synthetic white noiseand acoustic noise will be injected 2pSP9.Equal-likelihood decision making with limited information. RichardPitre (Naval Res.Lab., Washington,DC 20375-5350) andmatching pursuits will be usedto attemptto removenoise from these signals. Performance measures are examined for a detector-estimator based on anequal-likelihood signal probability model IN. R. Davisand R. Pitre,J. Acoust.Soc. Am. 97, 978-992 and993-1005 (1995)]. With limitedinte- grationtime and SNR, detection and parameter estimation analysis based 3:00 solelyon estimationof cumulantsis incomplete.Conventional perfor- mancemeasures like pfa anduncertainty measures such as cost uncertainty 2pSP6. Noise isolationand reductionusing spline wavelets. Phillip and decisioninformation loss are examinedas a functionof integration L. Ainsleigh (Naval Res. Lab., Underwater Sound Reference timeand estimation resolution. [Work sponsored by ONR(NRL).] Detachment,Orlando, FL 32856-8337)and CharlesK. Chui (TexasA & M Univ.,College Station, TX 77843-3368) A techniqueis introducedfor removingunwanted components from datausing B-spline-based multiresolution (B-wavelet) analysis. The time andfrequency localization capabilities of waveletsallow two advantages 4:15 overstandard filtering methods: (1) betternoise detection arising from the 2pSPI0. Effect of ergodicity failure on detection performance ability to isolate noisy componentsin wavelet bandswhere the signal prediction. GeorgeE. Ioup (Dept.of Phys.,Univ. of New Orleans,New energyis smallrelative to the noiseenergy, and (2) lesssignal loss by Orleans,LA 70148), Lisa A. Pfiug (Naval Res. Lab., StennisSpace selectivelyfiltering only thosesegments within wavelet bands containing Center,MS 39529),and JulietteW. Ioup (Univ.of New Orleans,New unwantednoise. The procedureis usedto removeimpulsive noise from Orleans,LA 70148) timeseries, and to eliminatemultipath interference from frequency domain data. Formulasbased on the noisevariance and the firstfour signalmoments topredict the performance at the minimum detectable level of ordinaryand higherorder correlation central ordinate threshold detectors have been derived,The passiveprediction formulas have been reported and will be 3:15 published.The activeprediction results have also been presented. These predictionformulas agree remarkably well with computer-basedMonte 2pSP7. A method of analysisof acousticemission signals due •o Carlo simulations.A breakdownin the agreementhas been observed for leakageby wavelettransform. Q.M. Chen,Y. S. Ho, andT. P. Leung simulationscontaining a smallnumber of samplepoints--in the observa- (Dept.of Mech.and Marine Eng., The Hong KongPolytechnic Univ., tionwindow for thepassive case and in thesignal for theactive case. This HungHom, Kowloon, Hong Kong) breakdowncan be traced to theinapplicability of theergodicity assumption In the testof continualacoustic emission due to leakage,the rms was for varioustime averages over a smallnumber of samplepoints, since key usedto evaluatethe energy of AE signals.However, the valueof rms stepsin thederivations contain the interchange of expectations and sum- stronglyrelates to measuringconditions, including sensitivity of sensor, mationsfor nonlinearterms. Small sample number time averageslead to mountingpressure, setting amplification, etc. Detectingpoints of sharp correlationcentral ordinate value probability density functions which are variationof AE signalsby wavelettransform to evaluateleakage is ex- non-Gaussian.Prediction errors in the formulasas greatas 2 dB are ob- ploredin this paper.The parameterevaluating leakage is samplezero- servedfor simulationswith 32 samplepoints. These errors decrease as the crossingcounts of wavelettransform at eachscale. Based on the sharp numberof samplepoints is increased.Both passive and active examples variationof AE signalsinstead of amplitude,this methodis robustto aregiven. [Research supported by ONR/NRL-SSC.] measuringconditions. The experimentalresults obtained under different testconditions demonstrates the applicabilityof the method. 4:30 3:30-3:45 Break 2pSPll. Frequencynormalized leakage correction technique. Casey R. Winkel,Kenton A. Shipley,a)P. G. Vaidya,and Tim A. Doughtyb) (Dept.of Mech.and Mater. Eng., Washington State Univ., Pullman, WA 99164) 3:45 Leakageis a problemin nearlyall aspectsof signalprocessing, espe- 2pSPS.Design of M-sequencesfor a shallowwater transmission ciallywhen the FFT is involved.Leakage takes the form of widefrequency experiment.S.E. Forsythc(Underwater Sound Reference Detachment, Naval Res. Lab., P.O. Box 568337, Orlando,FL 32856-8337)and spikesdue to a "spillingover" of informationacross frequency bins and occursmost often when the sampling frequency is notan integermultiple MohsenBadicy (Office of NavalRes., Arlington, VA 22217-5660) of thebase frequency. The leakage correction method presented here sub- Narrow-bandsignals centered at frequenciesfrom 600 Hz to 7 kHz stantiallyreduces this problem. The methodresamples the original time weretransmitted from a fixedprojector to a fixedhydrophone array located domaindata within specified limits. A frequencyerror measurement is 200 m awayas part of theshallow water acoustic/geologic experiments at takenfor eachsampling rate within the defined limits. The minimum fre- theNew JerseyAtlantic Generating Station Site. Both the projector and quencyerror is recordedalong with the fundamentalfrequency of the hydrophonearray were fixed 2 m off theocean floor in roughly15 m of record.This methodresamples the entire signal one record at a time with water.The signalswere Gaussianpulses I m in width modulatedby a linearinterpolator. Nyquist criteria must be satisfiedat all timesto vali- weightedbinary maximallength sequences (M-sequences). These datethe useof the linearinterpolation. Nyquist criteria is satisfiedif the M-sequenceswere designed to increaseeffective signal-to-noise ratio samplingrate is at leasttwice as largeas the highestfrequency in the while retainingthe time/spacediscrimination of the original Gaussian signal.The resampleddata must satisfy three conditions to eliminateleak- pulse.The pulse width was narrow enough to allowseparation of compo- age.(1) 2• pointsper period. (2) Integernumber of periodsper record. (3) nentarrivals (e.g., direct and bottom reflection). A designmethod is pre- SatisfyNyquist criteria. The methodhere satisfies these conditions and sentedthat allowssimultaneous control of frequency-and time-domain resultsin enhancedtime domaindata. a)Now at MartinMarietta, Knolls contentof thetransmitted signal. Examples of recoveryof thetransmitted AtomicPower Labs, Schenectady, NY. blNowat Dept.of Mech.Eng., signalsand their multipath information are presented. PurdueUniv., West Lafayette,IN. 3311 J. Acoust.Soc. Am., Vol. 97, No.5, Pt. 2, May1995 129thMeeting: Acoustical Society of America 3311 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 4:4• referto the lengthscales of the orderof k and aboveas the macroscales, and to the lengthscales much smaller than •, as the microscales.A com- 2pSP12. A study of the effectiveproperties of complexscatterers plexityfrequently encountered in scatteringproblems is theone character- usingmultiresolut'on decomposition. B.Z. Steinberg(Univ. of Tel ized by a microscaleheterogeneity that occupiesdomains in spacemea- Aviv, Tel Aviv 69978, Israel) and J. J. McCoy (CatholicUniv. of sured on the macroscale.A new formulation,tuned to govern the America,Washington, DC 20064) macroscaleresponse component, has been presented in severalrecent pa- Complexityin thecontext of radiationand scattering of wavescan be pers.This formulationis sufficientfor estimatingthe radiationof a sound intuitivelyperceived as the analyticaland computationaldifficulties en- field into the far-fieldof a surroundingfluid. In this presentationwe con- oounteredwhen a radiatingsystem interacts with a mediumor a scatterer centrateon the formulation'simplications. The questionsaddressed are: that are describedon a wide rangeof lengthscales. The wavelength•, What type of microscalebeterogeneity has no footprintin macroscale constitutesa physicallymotivated discriminator of the variouslength responsemeasures? What classesof microscaleheterogeneity have an scalespertaining to a time harmonicscattering problem. It is convenientto identicalfootprint in macroscaleresponse measures? WEDNESDAY AFTERNOON, 31 MAY 1995 CONGRESSIONAL HALL B, 1:15 TO 4:15 P.M. Session2pUW Underwater Acoustics:Propagation (Poster Session) Richard B. Evans, Chair ScienceApplications International Corporation, #2 Shaw• Cove,Suite 203, New London,Connecticut 06320 ContributedPapers All posterswill be on displayfrom 1:15 to 4:15 p.m. To allow contributorsan opportunityto see other posters,contributors of odd-numberedpapers will be at their postersfrom 1:15to 2:45 p.m. and contributorsof even-numberedpapers will be at their posters from 2:45 to 4:15 p.m. 2pUWI. The status of Naval underwater acousticmodeling. Paul C. is studiedin termsof theensemble-averaged two-point coherence function Etter (P.O. Box 5622, Rockville,MD 20855-5622) and the equationgoverning the coherencefunction is derived.In orderto insureenergy conservation when the generalizedmodal field equations are Resultsfrom a surveyof recentdevelopments in Naval underwater simplified,the parabolicapproximation is replacedby a methodwhich acousticmodeling are comparedwith thoseof two previoussurveys con- includesboth forwardand backwardpropagating fields. The two-point ductedat 8-yearintervals [P. C. Etterand R. S. Flure,Sr., J. Acoust.Sec. coherencefunction is expressedas the sumover both self-modal and cross- Am. Suppl.l 65, S42 (1979);P. C. Etter,J. Acoust.Soc. Am. Suppl.i 82, modalcoherence functions. The differencebetween the equations govern- S102(1987)]. All surveyscover basic acoustic models and sonar perfor- ing the self-modalcoherence functions and the cross-modalcoherence mancemodels. Basic acoustic models include propagation, noise, and re- functionsis considered.A numericalexample which uses typical shallow verbemtionmodels. Sonar performancemodels integrate basic acoustic waterparameters is presented.Figures portray how the modeenergies are models,signal processing models and supporting databases into cohesive transferredbetween the modesas the acousticalfield propagates.[This operatingsystems organized to solvethe activeor passivesonar equations work waspartially supported by ONR.] [P. C. Etter,Underwater Acoustic Modeling (Elsevier, Amsterdam, 1991); 2rided. (Chapman& Hall, 1995)].Summary tables identify and highlight 2pUW3. Investigation of three-dimensional bathymetric refraction noteworthycharacteristics of 83 propagationmodels, 15 noisemodels, 14 using laboratory scale modeling. Stewart A. L. Glegg, Anthony revet'oerationmodels, and 14 sonarperformance models. These surveys LaVigne,and Joseph M. Riley (Ctr. For Acoust.& Vib., FloridaAtlantic providea retrospectiveview of modelingdevelopments over the pasttwo Univ., Dept. of OceanEng., Boca Raton, FL 33431) decades and document a 160% increase in the number of models that are now availablefor applicationsin sonartechnology. This updatedbaseline Experimentalmeasurements have been carried out to identifythe effect alsosuggests future directions for Naval modelingin an em of defense of bathymetryon three-dimensionalunderwater ,sound propsgallon. The conversionincluding new applicationsin oceanographicresearch. measurements have been conducted over a 1/10 000th scale model of the 2pUW2. Combined volume and surface scatteringin a channel using SantaLucia Escarpment off thecoast of California.Experiments measured a modalformulation. ShimshonFrankenthal and M. J. Beton (Dept.of thebearing error obtained in locatinga sourcewith a horizontalline array Elec. Eng., CatholicUniv. of America,Cardinal Station, Washington, DC usinga phase-wavebeamformer. The resultsof thisexperiment demon- •64) stratedsignificant variations in the measuredbearing error. Differences in the detectedbearing of the variationsbeamformer and the actual source In previouswork, a modalapproach was used to studyrandom volume locationwere as large as 18 deg,with the magnitude of theseerrors being scatteringin a shallowchannel [M. J. Beranand S. Frankenthal,J. Acousl. a functionof bearingline andsource frequency. An analyticalsolution of $oc.Am. 91, 3203-3211(1992)]. Here, the way to includethe effects of theacoustic field in a shearsupporting wedge using the method of images a roughchannel surface in the formulationis shown.To includethe effects hasbeen used to approximatethe resultsof the bearingerror experiment. of a roughsurface, the modesare takento be dependenton the rangeand Comparisonof experimentand theory shows the same effects with beating transversecoordinates in additionto the depthcoordinate. The propagation errorsof the samemagnitude. [Work supported by ONR.] 3312 d. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3312 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 2pUW4. Modeling range-dependentpropagation using trapped and 2pUW7. Fluctuations of high-frequencyacoustic pulses in shallow leaky wedgemodes. JohnA. Fawcett (SACLANT UnderseaRes. Ca'., waler. MarciaA. Wilson (Naval Res. Lab., Code 7174, Bldg. 1005, Viale San Banolomeo,400, 19038 La Spezia, Italy), Evan K. SteanisSpace Center, MS 39529) Westwood (Appl. Res. Labs.,Univ. of Texas,Austin, TX 78713-8029), and ChristopherT. Tindie (Univ.of Auckland,Auckland, New Zealand) High-frequencyacoustic propagation and scatteringexperiments were conductednear Panama City, FL, in Augustof 1991 and 1993,and in The useof coupledwedge modes in modelingrange-dependent under- EckemfordeBay, Germanyin May 1993.The PanamaCity sitehas a hard wateracoustic propagation has been previously described by Primackand sandbottom, but the bottom of EckernfordeBay is softmud. Environmen- Gilbert[H. Primackand K. E. Gilbert,J. Acoust.Soc. Am. 90, 3254-3262 tal measurementswere madein conjunctionwith acousticmeasurements. (1991)].Their approach has been extended by usingleaky modes, in ad- The waterdepth at bothsites was approximately 30 m. The sourcesand the dition to the trappedones, in wedgemode computations. Trapped modes receiverarrays were mounted6 to 8 m from the bottomand were separated decayexponentially in the basementand correspond,in termsof rays, to by about90 m. A bottomreflected signal was detected in PanamaCity, and anglesof propagationwhich are totallyinternally reflected above the base- in some cases,in Germany.The sofl mud bottom of Eckemforde Bay, ment interface;leaky modes arc not well behavedin the basement,but however,absorbed most of the energydirected toward it. Data from pulses providean exeellenldiscrete approximation to the continuousspectrum 1.0 ms in length,at l-s intervals,will be shownfor frequenciesfrom 20 to contributionin the watercolumn. Because leaky modesare includedin the 180 kHz. Means, standarddeviations, and coefficients of variation of 100 computations,it is possibleto model accuratelyshallow water environ- or 150pulses for eachfrequency characterize two scalesof temporalvari- ments where trapped/leakymode conversionsare important.Within a abilityin the data.Data from severalof the receivinghydrophones are singlewedge domain, adiabatic wedge mode theory is usedfor computa- compared.Spatial variability is shownand relatedto modeledand mea- tions;at wedgejunctures, a least-squaresmode coupling scheme is em- ployed.Numerical examples where the results of thecoupled wedge mode suredchanges in thesound velocity profile. [Work supported by the Office methodare comparedto parabolicequation and standardadiabatic mode of NavalResearch.] computationsare presented. 2pUWg. Jovian acoustics:Short-range observation and long-range 2pUW5. Accuracy of parabolic approximationsfor travel time. F. prediction, MichaelD. Collins,B. EdwardMcDonald (NavalRes. Lab., D. Tappertand M. G. Brown (Appl.Marine Phys., Univ. Miami, RSMAS, Washington,DC 20375), W.A. Kuperman(Scripps Inst. of Oceanogr., 4600 RickenbackerCswy., Miami, FL 33149) La Jolla,CA 92093),and WilliamL. Siegmann(Rensselaer Polytechnic Inst.,Troy, NY 121g0) Many differentfull-wave parabolic approximations are analyzedwith regardto the accuracyof their travel time predictionsby consideringthe Waveswere observed propagating in the stratosphereof .Iupiternear geometricalacoustic (ray tracing)limit. The two small parametersare the impactsites of severalof the fragmentsof CometShoemaker-Levy 9. e=(l -n2)12and tz=p212, where n isthe depth and range-dependent index Concentricrings appearing in Hubble SpaceTelescope images have ten- of refractionand p is a scaledray grazingangle. By expandingthe exact tativelybeen identified as gravityand acoustic waves based on theirhori- and approximateHamiltouian and Langrangianfunctions in powersof ß zontalgroup speeds of 450 and900 m/s. Interpretingthe imagesis com- and/•, which tend to have the sameorder of magnitude,it is foundthat plicatedby the fact that the outerring is locatedamidst the debrisof the amongthe class of parabolicapproximations that can be implementedwith collapsedfireball. Since the fireballrose back through the obliquelyori- the efficient "split-stepFourier" algorithmonly the recentlydeveloped entedpath of the incomingfragment, the debrisfield is asymmetricand ca-insensitiveapproximation [Tappert et el., J. Acoust.Soc. Am., to be offsetfrom the impactsite. It is thereforeunlikely that the outerring is part published[has full second-orderaccuracy. The highlytouted "modified of the debris.If wavesare observedfar from the impactsites, they might log"parabolic approximation of german et al. [J. Acoust.Soc. Am. 86, provide new informationabout the Jovian atmosphere.A three- 228-233 0989)] hasonly first-order accuracy, the same as the "standard" dimensionaladiabatic mode solution predicts that the Jovianzonal winds parabolicapproximation, and furthermoreit hasa second-orderbias to- causehorizontal caustics to form to the eastand westof the impactsites wardtimes that are too early. Numerical calculations confirm and quantify about10 h afterimpact. An adiabaticmode solution has also been derived theseresults. [Work supported by ONR.] for gravitywaves, which exhibit similar horizontal caustics. Although the 2pUW6. Acousticinteraction with a propagatinginternal soliton acousticand gravity wave equations are drastically different, the horizontal wave packet in shallowwater. MichaelK. Broadhead(Code 7173, waveequations for the modecoefficients are identical. Naval Res.Lab., StennisSpace Center, MS 39529-5004) 2pUW9, Three-dimensionalacoustic propagation in a waveguideof variable thickness. RobertA. Coury,William L. Siegmann (Rensselaer One-way oceanacoustic propagation through shallow water internal PolytechnicInst., Troy, NY 12180-3590),and Michael D. Collins waveswas numericallysimulated, where the oceanographicmodel con- (NavalRes. Lab., Washington, DC 20375) sistedof a two-layerdensity/temperature stratified fluid overlyingfiat bathymetry.For sufficientlysmall amplitudes in a losslessmedium, shal- The parabolicequation (PE) methodhas proven to be an efficient low waterinternal waves are governed by theKorteweg-de Vries (KdV) methodfor solvingrange-dependent ocean acoustics problems. Recently equation,which possesses solitoh solutions. A finitedifference scheme was an extensionhas beenmade to handletwo-dimensional waveguides of usedto numericallytime evolve initial conditions,the detailsof which varyingthickness. This type of modelingis necessarywhen the upper determinethe number and properties of thesolitoh events that emerge. The boundaryof thewaveguide is allowedto change,as for examplein propa- internalwaves (in a center-of-massframe) were introducedthrough the gationup a beachor in an oceanwith a graduallyundulating surface. The indexof refractionin theacoustic wave equation. Range-dependent normal modeand PE modelswere used to computetransaction-loss for various adiabaticmode PE is anotherextension that hasbeen developed to solve frequencies(100 Hz-10 kHz), for differenttimes during the solitoh wave globalscale, three-dimensional propagation problems. In thispaper, the packetevolution, and for differentinitial conditions.For lowerfrequen- three-dimensionaladiabatic mode PE is extendedto handleproblems in- cies, refraction effects caused an increase in the IlleRtl TL level due to volving a gradualrange dependence in the overall thicknessof the wave- increasedbottom interaction, while for higherfrequencies, the predomi- guide.The modifiedadiabatic PE hasseveral applications. On relatively nanteffect was spatial/temporal fiuetuafions and the enhancementof sur- smallscales, it maybe appliedto solvethree-dimensional beach acoustics faceduct propagation. Dispersive terms exist for all but specialinitial problemsor to modeldiffraction by an island.It mayalso be appliedto conditions,but their amplitudeswere generallytoo low to be significant. solveglobal-scale seismoacoustic problems in whichtopography on the [Supportedby Office of NavalResearch and Naval Research Laboratory.] continentsplays a significantrole. [Work supported by ONR.] 3313 J. Acousl.Soc. Am., Vol. 97, No. 5, Pt. 2, May ! 995 129th Meeting:Acoustical Society of America 3313 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 2pUWI0. Global-scaleacoustic modding in an ocean overlying experiment.[Work supported by Officeof NavalResearch. Ocean Acous- rustic bathymetry.Gregory J. On-is,Michael D. Collins (U.S.Naval ticsProgram, code 321 OA, underthe initiativefor basicresearch in the Res. Lab., Washington,DC 20375), GrantDeane (ScrippsInst. of physicsof moderateto highfrequency acoustics.] Oceanogr.,Univ. of California,San Diego,La Jolla,CA 92093),and 2pUVq14. Propagation characteristics from the trans-Arctic Michael B. Porter (New JerseyInst. of Taehnol.,University Heights, propagation source as measured at a receiver in the Lincoln Sea. Newark, NJ 07102) ThomasN. Lawrence,Ilene McCool, and Nancy R. Bedford (Appl.Res. Labs., Univ. of Texas, P.O. Box 8029, Austin, TX 78713-8029) A three-dimensionalpropagation model is presentedthat takesinto accountthe elasticproperties of the oceanbottom and is applicableto The trans-Arcticpropagation (TAP) sourcewas a Russiandevice de- problemsof longrange and low frequencies.This methodallows global- ployednorth of Svalbardtransmitting at about20 Hz. Transmissionsre- scalecalculations appropriate for oceanmonitoring programs to he per- eelred in the Lincoln Sea north of Eilesmere Island were recorded on a formedwith environmentsfor which solutiontechniques have beenhere- tofore unavailable.The model is an extensionof the adiabaticparabolic- 20-elementvenieal array located on thecontinental shelf. The propagation equationmethod, which uses the normal-mode solutions in thewaveguide pathbetween the source and receiver is overthe Arctic Mid OceanRidge, for thedepth dependence of the acoustic field. A modifiedtwo-dimensional then skirtingthe Morris JesupPlateau, and finally propagatingup the continentalslope. The ice coveralong this path of propagationis highly parabolicequation model is usedto determinethe rangeand azimuth varied,ranging from central Arctic roughness levels (usually about 1-2.5 dependenceof the acoustic field, thus providing a three-dimensionalsolu- tion. It is shownthat the inclusionof elasticmaterial, with bothcompres- m standarddeviation) to the higherroughness (about 4 m s.d.)of the CanadianArchipelago. Amplitude and phasefluctuations of signaland sionaland shearwaves, in bathymetficfeatures causes larger loss and environmentalnoise over variedtime periods,and the resultsfor the sta- largershadow zones behind sea mounts and islandsdue to the effective tisticalcharacter of the watercolumn will he presented.Comparisons will softeningof thematerial. The methodis compared with exact solutions and he made with modeledresults to help determinethe effectsfrom this experimentalresults and is foundto he in excellentagreement for regimes for whichthe adiabaticapproximation is valid (i.e., for regionsof slowly complexenvironment and to predictthe impactof variationin ice condi- varyingbathymetry and sound-speed profiles). tionsalong the propagationpath. 2plJWll. An accurate,effident rough surface parabolic equation 2pUWIS. Mode vector parabolic equation, AbroadT. Abawi, W. A. program. Allan P. Rosenbergand Steven E Mugruder (JohnsHopkins Kuperman (Marine Phys. Lab., ScrippsInst. of Oceanogr.,Univ. of Univ.,Appl. Phys. Lab., 7-334, Laurel, MD 20/23-6099) California,San Diego, La Jolla, CA 92093-0238), Michael D. Collins (NavalRes. Lab., Washington, DC 20375),and MichaelB. Porter (New JerseyInst. of Techaoi.,Newark, NJ 07102) The parabolicequation program Fepe has been extended to handlea roughair-water interfacetreated as a seriesof stairsteps. Because much finervertical spacing may be neexledto resolvethe interfacethan to propa- A modevector parabolic equation (MVPE) is derivedfor thepropaga- gatean acousticwave accurately in therest of thedomain, an optionto use tion of normalmodes in the oceanwaveguide. This model,which includes one verticalspacing near the surfaceand a courserone in the restof the modecoupling, is a generalizationof theadiabatic mode PE [M.D. Col- oceanhas been implemented. The necessaryGalerkin approximations of lins,J. Acoust. Soc. Am. 94, 22690993)]. The main features of thismodel derivativeson an unequallyspaced grid havebeen worked out usingthe are:{1) It is basedon an initialvalue differential equation which propa- symbolicmanipulation program Mathematica. A testcase with a realistic gatesnormal modes rather than a methodthat involves matching solutions surfaceis providedto demonstratethe accuracyof the new program at interfaces.(2) The solutionvector whose components are the amplitude Fepe_rsfe.The code is efficientenough to allow thousandsof runs for of the modesis not derivedfrom a procedureinvolving a referencewave realisticsized problems, for exampleto simulatethe effectof a moving numberand thuseach vector component is locally accuratearound each surface.['Work supported by theoffice of theChief of NavalOperations.] mode.O) It agreeswith previousbenchmark solutions. (4) The modelis tractablein threedimensions. MVPE hasthree parts: Spatial derivative of 2pUWI2. Modeling a directional sourcein an underwater acoustic the modeamplitudes, eigenvalue, and couplingcoefficients matrices. The waveguide. RichardB. Evans (SCi.Appl. Intl. Corp.,#2 Shaw'sCove, latter two are precomputed;the coupling matrix is basedon McDonald's Ste. 203, New London,CT 06320) formulationin termsof environmentalparameters which is summarizedin [McDonaldet aL, I. Acoust.Sec. Am. 96, 2357 (1994)].The systemof Techniquesfor modelinga single frequencydirectional source in an equationscan either be solvedby matrixinversion or iteration.To illustrate underwateracoustic waveguide are appliedand tested. The techniquesare the method,the solutionto the problemof propagationof waves in a evaluated,with regardto accuracyand efficiency,for usein predictionof two-dimensionalwedge is presentedin detail. sourceperformance. Existing discussions of the topic oftenfocus on one 2pUWI6. Application of the mode vector parabolic equation to the technique.Here, the goal is to considera largerclass of methods.They 3-dimensional wedge problem. Abroad T. Abawi and W. A. range from mode matchingin the far-field, of the source,to the direct Kuperman (Marine Phys.Lab., ScrippsInst. of Oceanogr.,Univ. of applicationof a free-spacebeam pattern at rangezero. The techniquesare California,San Diego, La Jolla,CA 92093-0238) appliedto problemsthat arise due to spameaessof calibrationdata and the inappropriatenessof a free-spacebeam pattern for waveguideapplications. [Worksupported by ARA.] The MVPE [Abawiet el., thissession] is appliedto theproblem of propagationof wavesin a 3-dimensionalcoastal wedge and the resultsaxe 2pUWI3. Comparisonof theory and experimentof acousticbottom comparedwith thosewhen horizontal coupling is neglectedand with the penetration in a shallow water site. Nicholas P. Chotiros, Morris resultsobtained from conventional 3-dimensional methods. The compo- gtern,Adrienne Mautner (Appl. ,Res. Labs., Univ. of Texas,P.O. Box nentsor the solutionvector are the amplitudesof the verticalmodes which 8029, Austin,TX 78713-8029), Age Kristensen,and Enzo Michelozzi are coupledin both rangeand azimuth.The couplingmatrices for both (SACLANTUndersea Res. Ca'., 19026 La Spezia,Italy) rangeand azimuth are precomputedby the methodsummarized in [Mc- Donald et al., I. Acoust.Soc. Am. 96, 2357 (1994)]. In the absenceof Signalsfrom a sparksource in waterand received by acousticsensors modecoupling, the solutionreduces to the solutionof the adiabaticmode buriedin a sandysediment in a site off La Spezia,Italy, are comparedto parabolicequation [M.D. Collins,I. Acoust.Soc. Am. 94, 2269 (1993)]. theoreticalmodel predictionsfrom a fast field model. The model is a The systemof equationsare numericallysolved by the Crank-Nicholson modificationof OASES 1.6 that includesBiot's poreelasticwave propa- finite differencemethod. For a singlevertical mode, this systemof equa- gationmodel. The receivedacoustic pulses are comparedto determinethe tionsclosely resembles a system of diserefizedparabolic equation in range transfer function from the in-water source to the buried acoustic sensors. andazimuth. For multiplemodes, the manicesinvolved are band diagonal From a theoreticalpoint of view. the sedimentis treatedas a poro•!astic with the couplingmatrices appearing in their diagonal.The sizeof these solid governedby Biot's theoryof acousticpropagation. It is predictedto matricesare thus equal to the numberof pointsin azimuthtimes the supporttwo acousticwaves. Comparisons are made betweentheory and numberof verticalmodes. When the physics of theproblem is containedin 3314 d. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Sociely of America 3314 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp a subsetof coupledmodes, this methodoffers additional advantages in ducedby factorsof 10 and 5, respectively,with no lossof accuracyor numericalcomputation over the conventional3-dimensional methods. computationalparallelism, making its computationalrequirements similar to othersolution techniques. Because the weightingsof variousgrid ele- 2pUW17. Semiclassicaltechniques for long-range, low-frequency mentsin this methodare basedon the sourcefrequency, its usefulnessin propagation. Frank S. Henyey,Stephen A. Reynolds,and Terry E. TD calculationswith pulsedsources is limited. Despitethis, somelow- Ewart (Appl.Phys. Lab., Univ. of Washington,1013 NE 40thSt., Seattle, frequencyTD calculationsare possible. Applications and limitations of the WA 98105) higher-ordermethod will be presented. [Work supported byONR.] The Chester,Friedman, and Ursell (CFU) uniformasymptotic expan- 2pUW21. A method for computingadiabatic modal wavefronts. sion near causticshas beenimplemented as an adjunctto a ray-tracing EvanK. Westwood(Appl. Res. Lab., P.O. Box 8029,The Univ.of Texas code.The methodis appliedto the propagationof 400 Hz soundfrom a at Austin, Austin, TX 78713-8029) 200-mdeep source in a Munk sound-speedprofile through a rangeof 300 km. Makingthe parabolicapproximation in the ray trace,the validityof An approachhas been developed for determining the modal wavefronts "semiclassical"wave functions with theCFU expansionnear caustics can thatallow normal modes to be propagatedadiabatically in smoothlyrange- be determinedby comparisonwith a parabolicequation code. Good results dependentocean waveguides. The methodis motivatedby thefact that for the semiclassicalwave function are found.If the CFU expansionis not propagationin an isospeedpenetrable wedge is accuratelymodeled by used,the field is badlyinaccurate over hundreds of metersin the vertical. "adiabaticwedge modes," which are identicalto the usual"vertical A videoof the propagationcomparing the Wigherfunction with the ray modes"except that the wavefront curvature induced by thesloping bottom depth-angieplot is shown.[Work supported by ONR.] is takeninto account.For the wedge,the wavefrontsare assumedto be circulararcs centered on thewedge apex. In orderto generalizethe notion 2pUW18. Probabilisticrange dependencein a numericalaverage of wedgemodes to othertypes of rangedependence, wavefronts are con- underwateracoustic propagation method. RogerM. Oba (NavalRes. structednumerically such that the derivative of eachmode in thedirection Lab.,Stennis Space Center, MS 39529-5004) normalto its wavefront,c•ckl•s, is zero. The result is that the first-order A computationalmethod for forward propagationof the Helmholtz modalcoupling coefficients, which involve 8cbl3s integrated over depth, equationhas been developed for numericallycomputing average complex arezero, and the adiabatic algorithm can be used.The quantitiesc•cbl& and pressurefield in a singlepass. It usedsound-speed profiles be piecewise c•cbl)rversus depth are usedto obtainthe directionsnormal to the wave- probabilisticallyindependent in finitesized range steps to calculatetrans- front. For the isospeedpenetrable wedge, wavefronts computed in this missionloss and phasefor the averagesolutions in the continuouswave mannerdo indeedcorrespond closely to theexpected circular arcs. [Work case.This required that the uncertainty is probabilisticallymodeled within supportedby theARL Internal Research and Development Program.] rangeintervals as ensemblesof soundspeeds which were independent 2pUW22. A comparison of broadband and narrow-band fromone range step to thenext. This method can be modifiedto represent transmissionloss in shallowwater. KarenD. Frech (Bolt Beranekand certaincases for whichthere is statisticaldependence in range.This can be Newman,1300 North 17th St., Arlington, VA 22209) achievedby nonlocalaveraging over several range steps. The inter-relation of rangesound speed and statistical dependence will be considered,and Calibratedacoustic measurements were made at the HudsonCanyon resultsfrom numericalexperiment will be shown.Similar calculations Experimentsite [L. Maioccoand W. Carey,J. Acoust.Soc. Am. Suppl.1 allow the calculationof growthof standarddeviation over range.This 86, S8 (1989)]during area characterization test II(ACT ll) conductedin modification can also be considered in the limit of small intervals of un- September1993. This site was chosen because it is a surveyedarea with certainty.[Work supported by NavalResearch Laboratory and the Office of knowngeophysical and geoacousticproperties. Transmission loss was Naval Research.] measuredalong the previouslyrun radialsfrom borehole 6010 using calibratedsmall broadband explosive charge sources and a narrow-band 2pUW19.Characterization of oceanographic/acousticvariability in continuouswave (cw) towedacoustic projector. These sources were, for littoral regions:Examples from two diversetest sites. HassanB. Ali thepurposes considered here, co-located in rangebecause of low testship (Code7173, Naval Res. Lab., Stennis Space Center, MS 39529-5004) speed(under 5 kn). The receivingsensor was a 25 elementstationary As a resultof complexoceanographic and atmosphericprocesses in verticalline array spanning the majority of thewater column (73 m), with littoralregions, environmental parameters are characterized by consider- 19 elementsextending off the bottom(60 m) and6 elementsalong the ablespatial and temporal variability. The precedingimposes severe con- bottom(30 m). Usingthe principle of reciprocity,the hydrophone elements straintson signalprocessing schemes, thereby adversely influencing sys- at eachof the sourcedepths enabled comparisons of thetransmission loss tems based on acoustical, optical, magnetic, and oceanographic measurementsfor broadbandand cw sourcesto be made over a range parameters.Acoustic signals are degraded by extensive interaction with the intervalfrom 4-22 km at two frequencies(200 and900 Hz). The com- surfaceand bottom boundaries,the passageof internal waves, tidal parisonswere performed by means of linearregression of the data from the changes,ambient noise, the influx of freshwater from rivers and marshes, two sources.The resultsof the comparisonwill be presentedand will etc.It is unlikelythat these diverse phenomena will all be presentin any includea detaileddiscussion of theprecision of theresults and of possible singlegeographic area. Rather, the numberand significance of the phe- sourcesof experimentalerror. Finally, the cw transmission loss from ACT nomenawill varyfrom site to site.As a result,it is importantto identify II will be comparedwith the previousmeasurements of Maiocco and andcharacterize the germane ocean processes and environmental features Carey. at particularsites of interest,in orderto isolateand assess their acoustic 2pUW23.The effectof roughnesson acousticpenetration of the effects.The objectives of thistask are to ascertainthe minimum number of seafioor as given by a fluid-fluid perturbation model and oceanographicparameters controlling the acousticpropagation, and their comparisonwith recentsediment penetration experiments. John E. requisitespatial and temporal resolutions. The resultsof suchinvestiga- Moe, Eric I. Thorsos,Darrell R. Jackson,and Kevin L. Williams (Appl. tionsfor two diversesites off the U.S. andU.K. coastsare providedin this Phys.Lab., Univ. of Washington,1013 NE 40thSt., Seattle, WA 98195) paper. 2pUW20. Solution of the acousticwave equation in underwater Recentexperimental results [E E. Boyleand N. P.Chotiros, J. Acoust. Soc. Am. 91, 2615-2619 (1992)] reveal acousticpenetration from water environmentsusing an improvedfinite differencemethod, R.A. Zingarelli(Naval Res. Lab., Acoust. Simulation Section, Stennis Space intosandy sediments at grazingangles below the compressional critical Center,MS 39529) anglein relationto themean surface. These authors interpret the results to indicate the excitation of a biot slow wave in the sediment. An additional At thefall meeting,a finitedifference solution to the acousticwave mechanismfor subcriticalpenetration will be discussed,based on assum- equationfor realpressure fields, its implementation,and several applica- inga smalllevel of roughnessat the water-sediment interface. Computer tionswere presented. An improveddifferencing scheme developed by Cole simulationsof theseexperiments using theoretical calculations based on et al. hassubsequently been incorporated into this numerical model. Using Rayleigh-Riceperturbation theory for 2-D surfacesreproduce experimen- this methodruntimes and memoryusage for cw problemshave been re- tal results,indicating that the acousticpenetration of the surfacemay be 3315 d. Acoust.Soc. Am., Vol. 97, No.5, Pt. 2, May1995 129thMeeting: Acoustical Society of America 3315 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp dueto scattering(diffraction) from low levelsof roughness.The accuracy and can be correlatedwith specificsediment features. A discussionof the of perturbationtheory for the levelof roughnessbeing considered is veri- modelingresults in connectionwith bothenvironmental and acousticdata fied usingcomparisons with exactcalculations in the specialcase of I-D setswill be given. surfaces.[Work supported by ONR.] 2pUW27. Three-dimensional aconstic/geoacousticpropagation 2pUW24. Marching wave-number-integration approach to modelingof the New JerseyAtlantic generatingstation site. Mobsen range-dependent,two-way selsmoacousticpropagation modeling. Badicy (OceanAcoust. Prog., Office of Naval Res., Arlington,VA Hem'ikSchmidt (Dept. of OceanEng., MIT, Cambridge,MA 02139) 22217), GeorgeBotseas, Ding Lee (NavalUndersea Warfare Ctr., New London,CT 06320),and WilliamL. Siegmann(Rensselaer Polytechnic An approximatesolution to two-wayseismoacousfic propagation prob- Inst.,Troy, NY 12180) lemscan be obtainedby recursireuse of wave-number-integrationin a stepwiserange-dependent environment. The approachis conceptually Propagationeffects of 3-D geologicalfeatures in shallowwater sedi- simpleand straightforward. In the range-independent sector containing the meatlayers at theAriantic generating station (AGS} continental shelf site source,an "exact" integralrepresentation of the field can be obtained areinvestigated. Profiles of compressionaland shear sound speed, attenu- versusrange and depth using, e.g., the SAFARI/OASES code [H. Schmidt ation,and density have been generated from 23 availablegeological cores andE B. Jensen,J. Acoust.Soc. Am. 77, 813-825 (1985)].At thevertical at theAGS siteand discussed in connectionwith a recentacoustic experi- boundaryof thenext sector we thensolve the reflection-transmission prob- mentconducted there [Badicy eta/., J. Acoust.Soc. Am. 96, 3593-3604 lem locally for eachplane-wave component, assuming vertical homoge- (1994)].A 3-D geoacousticdata set is constructedfrom these profiles using neityof thefield. The resultingparticle motions now act as virtual sources, interpolationschemes based on Akima splines and on krieging. Correlation thewave-number representation of which can be statedexplicifiy using the propertiesof thesound speeds and density fields clearly show the existence seismicsouwe representation theorem. The resultingtransmitted and re- of sublayergeological features. The geoacousticfields, along with detailed fleetedfields can then be computedat any depthand rangewithin the bathymetryand watersound speed, are usedfor inputa 3-D frequency range-dependentsectors. The procedureis repeatedat anyvertical cut in a domainPE propagationmodel. Both 3-D and NX2-D simulationsare marchingscheme. A single-scatterapproximation to the backscattered field performedover a circularregion corresponding to the experimentalcon- is subsequentlyobtained by a backwardmarching scheme, similarly to the figurafion.Relative influencesof sedimentsound-speed structure and approachused in thetwo-way elastic PE [M.D. Collins,L AcouscSoc. water-sedimentinterface topography on transmissionloss are determined Am. 93, 1815-1824 (1993)].A specialversion of OASESincorporating for frequenciesup to I kHz. Simulationresults are comparedwith spectra thisapproach has been developed, and its performanceis demonstratedby obtainedfrom the broadbandexperimental transmission loss. solutionsto canonicalproblems such as theASA benchmark,and seismic 2pUW28. Use of empirical orthogonalfunctions to estimatewave problemspreviously solved using the two-wayelastic PE. number variance in a stochastic shallow-water channel. Michael J. 2pUW25. Comparison of exact and approximate solutions of Longfritz,William L. Siegmann,Melvin J. Jacobson (Rensselaer multiple scattering between interfaces in rough waveguides. Kevin PolytechnicInst., Troy, NY 12180-3590),and MohsenBadicy (Ocean D. LaPage (Bolt Betarickand Newman, Inc., 70 FawcettSt., Cambridge, Acoust.Lab., University of Delaware,Newark, DE 19716) MA 02138) The variances of horizontal acoustic wave numbers in stochastic Modelingpropagation in roughwaveguides introduces the interesting shallow-waterenvironments ave estimatedusing empirical orthogonal questionof howto treatmultiply scaUered waves. One approach is to treat functions(EOFs). Using perturbation methods and an adiabaticnormal- the roughsurface scattering at the waveguideboundaries under an mode propagationmodel, the wave number fluctuationsare related to tendedBorn approximation [W. Kupermanand H. Schmidt,J. Acoust.Soc. rangevariations in the oceanand/or sediment sound-speed profiles, which Arm86 (1989)].Under this approach multiple scatter effects are incorpo- canbe convenientlyand efficiently represented by EOFs.This relationship rated into the mean field througha second-ordercorrection in surface can be used to estimateboth the wave numberdeviations arising from roughness,and the scatteringamplitudes at eachinterface are assumedto selected realizations of the stochastic ensemble and the overall wave nnm- be drivenby the correctedmean field alone.Coupled integral equations bet variance.The procedureis illustratedby applicationto a shallow-water whichthe total field in a roughwaveguide must satisfy at the sourcedepth waveguidewith a multilayeredsediment bottom. Both the layer depths and areavailable in theliterature [D. Bennan,L Acoust.Soc. Am. 92 (1992)], theintralayer sound speeds are modeled as random variables. The accuracy makingit possibleto evaluatethe approximateresults in a consistentway. of theestimation procedure is investigatedfor variouschoices of the layer Here theresults obtained by solvingthe integralequations are compared to depthand sound-speedstatistics by comparingwith resultsfrom compu- thoseobtained by addingthe scatteredfield to eithera correctedor an tationalsimulations. A particularenvironment examined is theNew Jersey uncorrectedmean field. Conclusionsregarding the houndingbehavior of ShelfA0anticGenerating Site, where relatively extensive geoacoustic pro- the approximatesolutions are drawn for variousroughness and waveguide filesare available [M. Badieyet eL, J. Acoust.Soc. Am. 96, 3593-3604 parametersin the low frequencyregime. (1994)].Comparisons are made between results from the estimation pro- cedureand from the KRAKEN and FEPE propagationcodes. 2pUW26. Sedimentlayer structure and compositioneffects on pulse propagationat the Arianticgenerating station (AGS) site. KevinP. 2pUW29. Multiple ocean layering models and mode trapping in Boagiovanni (RensselaerPolytechnic Inst., Troy, NY 12180-3590), sublayersfor high frequencypropagation. N.A. Sidorovskaia(Dept. MohsenBadicy (Univ. of Delaware,Newark, DE 19716),and William of Phys.,Univ. of New Orleans,New Orleans,LA 70148) and M. E L. Siegmann (RensselaerPolytechnic Inst., Troy, NY 12180-3590) Wetby (NavalRes. Lab., StennisSpace Center, MS 39529) An investigationof broadbandpulse propagationin a shallowwater It is possiblefor sublayersin a layeredocean to have pronounced envlronm•nt is pe,rformcd using high-older frequency-and time-domain effectson the propagatingmodes in the watercolumn. For example,atypi- parabolicequation models. High resolutiongeoacoustical profiles are con- cal effectsoccur for soundspeeds less than the overlaying water column or structedfrom coresobtained at the extensivelysampled AGS site which someoverlying sublayers. In somecases one predictsthe concentrationof lies 5 miles offshoresouthern New Jersey.These, along with CTD and a large energyflux in that layer even at modeleigenvalues that prohibit detailedbathymetric dam, are used to model the environment.Acoustic propagationin the watercolumn while supportingpropagating modes in experimentsrecently conducted at thissite [M. Badicyet el., J. Acoust. the sublayer.Since some data suggest the possibility of underlyinggaseous Soc.Am. 96, 3593-3604 (1994)] providebroadband acoustic data for regionsthat supportlow soundspeeds, this is a practicalproblem. This comparisonswith the modelingpredictions. Simulations of wansmission allowsfor the possibilitythat for a layerthick enough to absorbenergy lossversus frequency show very goodagreement with experimentaldata beforearriving in a higherspeed sublayer, the numberof propagation over severaldifferent propagationtracks. 'Hme-domaln simulations are modesin the water columncan be reducedwith increasingfrequency. comparedwith time seriesof pressurevariations generated by the impul- Sincethis is a frequency-dependenteffect [effective (absorbing) thickness sive experimentalsource along correspondingtracks. Strongly range- of layersis inverselyproportional to wavelengthor directlyproportional to dependentmechanisms are observedover shortranges with hoth models frequency],absorption into the overlying sublayers becomes more pro- 3316 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3316 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp nouncedwith increasedfrequency thus reducing the possibilityof "tun- for the uppersediments on the continentalshelf of the LincolnSea, north nelling"which leads to a reductionin propagatingmodes in the water of EllesmereIsland, Canada. The experimentinvolved deploying an column. This effect is the converse of the usual case for ocean bottom ocean-bottomseismometer through 5 m of polarpack ice, andrecording layeringand can be directly measured. Some interesting effects are studied signalsfrom seafloorsources at rangesof 35-900 m. Subsequently,a andcompared with availabledata using the highfrequency mode model layeredcompressional-speed model of the uppersediments was deter- SWAMP.[Work sponsored by theOffice of NavalResearch.] minedfrom a travel-timeanalysis of refractedcompressional waves (head 2pUW30,Analysis of spatial-timecharacteristics of broadbandpulse waves),and a shear-speedmodel was determined by matchingthe ob- propagationthrough ocean sound channels by usingshallow water serveddispersion characteristics of shearand seismic-interface(Scholte) acousticalmode propagation model. NatalyA. Sidorovskaia(Dept. of waves.Frequency-dependent compressional and shearattenuation coeffi- Phys., Univ. of New Orleans,New Orleans,LA 70148) and Michael E cientswere estimated from an analysisof the decayof signalamplitude Werby (NavalRes. Lab., Stennis Space Center, MS 39529) with range:An approximatelylinear dependenceof attenuationon fre- Broadbandpulse propagation through an oceanicsound channel is quencywas observedfor both wave types.The sensitivityof acoustic investigatedto characterizesome important oceanic properties, namely, the propagationin the oceanto the variousgeoacoustic parameters was inves- verticalsound profile, bottomstructure, and also sourcelocalization. Ex- rigatedusing a numericalpropagation model. amplesof waveguideswith surface and bottom ducting are considered. The new fast normalmode method (SWAMP) basedon a new expansion 2pUW33. The relationshipbetween rays and modesin a waveguide methodallows one to studythe highfrequency range in whichlarge num- with large-scaleinhomogeneities, Anatoly L. Virovlyansky(Inst. of bersof modescan be excited.In thissituation the complicated structure of Appl. Phys.,46 UlyanovSt., 603600Nizhny Novgorod, Russia) thewavefront that is theresult of theinterference of thelow-order trapped refractivemodes and the high-orderreflected modes is observedin the The well-known resultsof Tindie and Guthrie, Felsen, and other au- waveguides.To understandthe structureof thisinformatively rich wave- thorson studyingthe relationshipbetween rays and normal modesin a front,two techniquesare presented:The staticspatial-time maps of the range-independentwaveguide are generalized for a waveguidewith large- soundfield intensity distribution in a waveguideand video movies permit- scaleinhomogeneities of refractiveindex. It is shownthat in complete tingone to observethe time evolution of a pulsethrough the fixed spatial analogywith therange-independent case, the raylike behavior of a cluster region.The later technique gives much additional information on thepro- cessand can offer additional insight into the natureof pulseevolution of normalmodes takes place. The notionof Fresnelzones for normal alonga waveguide.[Work sponsored by theOffice of NavalResearch.] modesis introduced,which is analogousto the usualFresnel zones intro- ducedfor rays.Using Fresnel zones for modesone can simplify the analy- 2pUW31. Scholte-Stoneleywaves on a solid layered ocean floor. sisof modescattering at large-scaleinhomogeneities (such as an opaque LouisHargenrader andHerbert 0berall (Dept. of Phys.,Catholic Univ., screenor an inhomogeneityof refractiveindex) in a waveguide.Simple Washington,DC 20064) and statisticalaveraging-suited formulas are deducedto calculatemode The existenceof a Scholte-Stoneleyinterface wave has been pointed amplitudevariations under scatteringat inhomogeneitiesof refractivein- out for the two-layerpropagation model of Pekeris,as generalizedto a dex, which are "mode analogues"of the formulasof geometricaloptics shear-supportingocean bottom. Further, the occurrenceof apparentreso- and thoseof the Rytov method. nancesin a solidsediment covering the oceanfloor has been noted IS. J. Hugheset al., J. Acoust.Soc. Am. 88, 1283(1990)]. By findingthe poles 2pUW34. Some general properties of ray arrival sequencesin an in the complexfrequency plane corresponding to the variousinterface- underwatersound channel. AnatolyL. Virovlyansky(Inst. of Appl. wave (Scholte-Stoneley)and trapped-wavemodes (including Love Phys.,46 UlyanovSt., 603600Nizhny Novgorod, Russia) waves),a detailedstudy is carried out of thevarious wave modes that exist in the elasticlayered problem taking note of theiridentities and of transi- Someproperties of ray arrivalsequences valid in a waveguidewith an tions betweenmode types, and the resonancebehavior associated with arbitrarysound-speed profile are ascertainedusing the simpleapproximate themis investigated. formulaconnecting differences in ray traveltimes and adiabaticinvariants 2pUW32. Measurementof upper-sedimentgeoacoustic properties in of their trajectories.It is notedthat the followingconservation law takes the Canadian high Arctic. S.E. Dosso (DefenceRes. Establishment place:The meandifference in travel timesof rays havingtheir launch Pacific, FMO Victoria, BC V0S lB0, Canada) and G. H. Brooke anglesinside the fixed narrowangular interval does not dependupon the (NumericalDecisions Group, Victoria, BC V8Z 3K3, Canada) distancebetween the sourceand the receiver.This law holdstrue not only Geoacousticproperties of the oceanbottom can significantlyaffect in therange-independent waveguide but in theadiabatically varying wave- acousticpropagation in shallowwater. However, to date,few measure- guide as well. Somegeneral conclusions concerning the relationshipbe- mentsof geoacousticproperties have been reported for the highArctic. A tween travel times and launchangles of rays reachingthe receiverare seismoacousticsurvey was carriedout to determinea geoacousticmodel made. 3317 J. Acoust. Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3317 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp THURSDAY MORNING, 1 JUNE 1995 MEETING ROOM 16, 8:30 TO 11:45 A.M. Session 3aAA Architectural Acoustics:Concert Hall and Opera House Acoustics GeorgeE. Winzer, Chair WinzerAssociates, 17721 Mill Creek Drive, Rockville, Maryland 20855 Chair's Introduction--8:30 ContributedPapers 8:35 bothcommercially available measurement systems and the measurement systemsof individualresearch groups. The initial resultswill compare 3aAA1. Computer model versus reality in a nonshoeboxorchestra measurementsfrom groups in NoCthAmerica, Japan, and Europe. Subse- hall. Part I. RichardH. Campbell (ECE Dept., WorcesterPolytech. quentwork will seekto explainthe causeof the observeddifferences. Inst., 100 InstituteRd., Worcester,MA 01609) The Portland(Maine) City Hall Auditoriumwas the venuefor acqui- sition of occupiedand unoccupiedacoustical data on 4 October 1994, 9:20 usingthe MLSSA system.During intermission,an omnidirectionalloud- speakerwas positioned at centerstage in the planeof the prosceniumarch 3aAA4. Technical matters relating to the measurementof interaural and occupieddata were collectedwith nearly a full audience.Three vol- cross-correlation(IACC) coefficientsin concert halls and opera unteersequipped with eyeglassmicrophone-pairs and DAT machinesoc- houses. TakayukiHidaka and ToshiyukiOkano (TakenakaRes. & Dev. cupiedsix preselectedseats in 3.5 rainto acquire18 binaural64-K impulse Inst., 5, 1-chome,Ohtsuka, lnzai-machi, Inba-gun, Chiba 270-13, Japan) responses.The sameseat locations were usedearlier in the day to obtain The interauralcross-correlation coefficient (IACC) hasbeen shownto theunoccupied data. An ODEON (c) computermodel of thishall, created be an importantmeasure, along with others,of the qualityof acousticsin by Kirkegaardand Associates,is usedto estimateacoustical parameters concerthalls and opera houses [Schroeder et al., J. Acoust.Soc. Am. 56, from the same source and receiver locations as used in the live audience 1199 (1974);Ando, ConcertHall Acoustics(Springer-Verlag, Berlin, acquisition.Particular attention is givento responsefeatures due to the 1985)]. When measuredin auditoriumswith binauralheads (real or designof thishall, whichis a double-balconyhorseshoe-shaped space with dummy)using an impulsesource, means must be adoptedto achieveac- curvedceiling. [Work supported by theConcert Hall ResearchGroup.] curacyand precision, and to selectthe typeof impulseand processing methodsto makeIACC mostuseful in theprediction of acousticalquality. 8:50 Subjectscovered include: (l) typeof impulse,(2) convolutionsignal, (3) integrationlimits, (4) directivityand positions of sourcein the hall, (5) 3aAA2. Computer model versus reality in a nonshoeboxorchestra parametersof head,(6) comparisonsof measurementsmade with realand hall. Part II. DavidGriesinger (Lexicon,Inc., 100Beaver St., Waltham, dummyheads, (7) valueof torso,(8) measuringpositions in hall, (9) MA 02154) comparisonof measurementsof IACC in hallswith upholstered and nonu- pholsteredseats, (10) comparison with IACC measurementsmade by other The Portland(Maine) City Hall Auditoriumwas the venuefor acqui- laboratories,and (11) somepreliminary data on differencesamong IACCs sitionof occupiedand unoccupiedacoustical data on 4 October1994, measuredin occupiedand unoccupiedhalls. usingthe MLSSA system.An ODEON (c) computermodel of thishall, createdby Kirkegaardand Associates, is usedto estimateacoustical pa- rameters from the same source and receiver locations as used in the live audienceacquisition. The data collectedin the hall are analyzedfor mu- 9:35 sicalintelligibility and revcrberance using new andmodified standard mea- 3aAA5. Determinationof categoriesof acousticalquality in concert sures.Comparisons are madeto theinformal impressions of thelisteners at halls using the questionnaireand interview method. Leo L. Betarick the concert. The relevant usefulness of the data estimated from the com- (975Memorial Dr., Ste.804, Cambridge, MA 02138-5755) putermodel is discussed.The role of computermodel surface definitions with respectto coefficientsof absorptionand diffusionis investigated. Thereare three common alternative techniques for judgingsubjective [Worksupported by theConcert Hall ResearchGroup.] acousticalquality in concerthalls and opera houses: (1) thebinaural com- pailsonmethod; (2) theexpert-group round-robin listening method; and (3) the questionnaireand interview method. The questionnaireand interview 9:05 methodwas utilized by me in rank-ordering55 concerthalls in 22 coun- 3aAA3. A room acousticsmeasurement system round robin. J.S. tries. Conductors,musicians, and music critics were interviewed and each Bradley (IRC, Natl. Res.Council, Montreal Rd., Ottawa,ON KIA 0R6, was askedto rank-orderthe halls he/sheknew well. In addition,to cover Canada) all halls,opinions were solicited from those who listen often to symphonic music in many halls, which includedacoustical consultants and selected This paper reportspreliminary results of a room acousticsmeasure- listenerswho travelextensively and attendsymphonic concerts. I have ment systemround robin. The roundrobin usesa commercialdigital re- attendedsymphonic concerts in all butsix. The hallswere then separated verberatorto representthree standardrooms that can be sent from one into six categoriesfrom A+(super), A(excellent), B+(good to excellent), measurementgroup to another.Thus the testscompare basic calculation B(good),C+ (fairto good), and C(falr). No rank-orderings were attempted proceduresand do not includethe effectsof variationsdue to typesand withineach category. It is probablethat some halls might be rankedone placementof transducers.Each participant measures octave band values of categoryhigher or one categorylower than its presentassignment if a monauralmeasures such as decaytimes, early/late ratios, and RASTI val- differentgroup if intervieweeswere selected. A shiftof twocategories is ueson threedifferent reverberator settings. Where possible, participants highlyunlikely. The resultsfor the 55 concerthalls are presentedand canalso measure interaural cross correlations. Initial comparisonsinclude discussed. 3318 J. Acoust.Soc. Am., Vol. 97, No.5, Pt. 2, May1995 129thMeeting: Acoustical Society of America 3318 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 9:50 qualitywith deviationsfrom optimum,of eachof theseacoustical at- tributes.By processof adjustmentof theconstants, the best fit betweenthe 3aAA6. Interauralcross-correlation (IACC), lateral fraction(LF), measuredphysical quantities and the subjectivedetermination of acousti- and low- and high-frequencysound levels (G) as measuresof cal quality of concerthalls is determined.Excellent correlation between acousticalquality in concerthalls. TakayukiHidaka (TakenakaRes. & Dev. Inst., 5, l-chome, Ohtsuka,lnzai-machi, Inba-gun, Chiba 270-13, thefinal result and the rank-orderings is obtained. It mustbe emphasized, Japan), Leo L. Betarick (975 MemohalDr., Ste.804, Cambridge,MA however,that other factors are importantin concerthall designwhich are 02138-5755),and ToshiyukiOkano (TakenakaRes. & Der. Inst.,Chiba not includedin this rating scheme,for example,the degreeto which mu- 270-13, Japan) sicianscan hear each other and hear themselveson stageand balance amongthe sectionsof an orchestra.There may be otherunknown acous- Interauralcross-correlation coefficient (IACC) and lateralefficiency ticalfactors that contribute to acousticalquality. (LF) ascorrelates with subjective ratings [see companion paper, L. Be- ranek,"Determination of categoriesof acousticalquality in concerthalls" (thissession)] were analyzed. To makeIACC sensitiveto qualityratings, a multi-octave-bandaverage was developed, based on Blauert et al. [Acus- tica59, 292] and on a subjectivelyderived set of equalASW contours that 10:45 showedthe 0.5, 1.0,and 2.0 octavebands to beof equalimportance. This IACC3 was divided into IACCE3 integrated over first 0.08 s afterarrival of 3aAA9. The use of the Sabine and Eyring reverberation time thedirect sound, and IACC[,3 same, 0.08 to 1 s.Subjective judgments were equationsto churches. Ant6nioPedro O. Carvalho (Acoust.Lab., alsomade to determinethe effects of increasedsound levels of symphonic Dept.Civil Eng.,Faculty of Eng.,Univ. of Porto,R. Bragas,P-4099 Porto musicat frequenciesabove and below 355 Hz on apparentsource width Codex,Portugal) ASW.IACCE3 and GL bothappear important for determiningASW. The measuredquantity [1 -IACCE• ] alonewas found to separatethe 17 concert Reverberationtime (RT) measurementswere taken at severalsource/ hallsof thisstudy for whichIACC datawere available into the samethree receiverlocations in 41 Catholicchumbes in Portugalbuilt in the last 14 categorygroups as thosedetermined from the interviews.Lateral fraction centuries,using the impulse-responsemethod. The useof the Sabineand (LF)was found to extend over a verysmall range and there were so many Eyringreverberation time equationswas tested to estimatethe measured overlapsamong halls when separation into three rating groups was at- RTsin thissample of chumres.The effect of coupledspaces was analyzed, temptedthat LF wasjudged not to besuitable for ratingacoustical quality. anda newalgorithm for theapplication of theSabine equation in churches wasdeveloped producing an averageof 16%in thedifferences between the 10:05-10:15 Break predictedand measuredRTs compared to 71% usingthe standardSabine equation.Coupled spaces were foundto act as windowswith a character- isticabsorption coefficient depending on theirdimensions. The recessesin 10:15 churcheswere grouped in threetypes: main altar area, chapels, and lateral 3aAA7. Correlationsbetween categories of acousticalquality for aisles,each having a particularacoustical behavior. It wasfound that those forty concerthalls and measuredphysical parameters for them: RT, recessesonly actedas coupledspaces if their length/opening_width>0.6 EDT, IACC, LF, G, ITDG, BR, C(80) and diffusion. Leo L. Beranek or if theaisle_width/opening_height>0.4 in lateral aisles. The remaining (975Memorial Dr., Ste. 804, Cambridge, MA 02138-5755) differencesfound between the RTs measured and predicted with this new algorithmwere hypothesized to berelated to whatwas called a reverberant Throughthe cooperationof manyacoustical laboratories, architects, ceilingeffect, which is presumedto be dueto a two-dimensionalreverber- and hall managers,physical measurements of reverberationtime (RT), antsound field that builds up near a verytall ceiling. [Work supported by early decaytime (EDT), early interauralcross-correlation coefficient INICT/Ministryof Planningand Univ. of Porto,Portugal.] [IACC(E)],lateral fraction (LF), sound-pressurelevel (G), initial-time- delaygap (ITDG), bassratio (BR), early/reverberant energy ratio [C(80)], anddiffusion [IACC(L)] have been collected in wholeor in partfor 66 concerthalls and l0 operahouses. RTs are for bothoccupied and unoccu- pied conditions;others are for unoccupiedstates. The parametersIACC or 11:00 LF, or both, are availablefor only 40 of the concerthalls. The above acousticalparameters for thesehalls are individuallycorrelated with the 3aAAI0. Evaluating acoustical qualities of four rooms using ratingcategories given in thecompanion paper [Beranek, "Determination questionnaires. Gary W. Siebein,Martin A. Gold, Mitchell Spolan, of Categoriesof AcousticalQuality in ConcertHalls"]. It is shownthat six andChristopher Herr (Arch.Tech. Res. Ctr., 231 ARCH, Univ.of Florida, of thesequantities seem necessary to correlatephysical data with the sub- P.O. Box 115702,Gainesville, FL 32611-5702) jectiveratings, namely, RT (or EDT), IACC(E), G, ITDG, BR, and some measureof diffusionnot yet developed. A largegroup of studentslistened to anechoicrecordings of musicand speechsamples at severallocations in fourdifferent performance rooms: a 10:30 large2000-seat multipurpose performing arts center; a blackbox theater; a 250-seatlecture hall; andan openfield. A brief pieceby Mozartplayed by 3aAA8. Toward an overall computationalscheme embodying the a stringquartet, a portionof a symphonyby Brockher,a soliloquyfrom modern acoustical measures and correlation of the scheme with the Hamlet,and standardspeech intelligibility word listswere played through categoriesof acousticalquality of concert halls as determined from a singleloudspeaker located at the centerfront of the performingarea of the questionnaire and interview method. Leo L. Beranek (975 the room.Students evaluated qualities of soundincluding clarity, intimacy, MemorialDr., Ste. 804, Cambridge,MA 02138-5755) envelopment,balance, reverberance, loudness, and overall impression on a An overallcomputational scheme for estimatingfrom modernacous- bi-polarsemantic rating scale. They alsotook speech intelligibility tests. tical measurementsthe acousticalquality of concerthalls is exploredin The overallimpression of the piecesof musicin the blackbox theaterand thisstudy. The methodshowing promise is basedon Ando [ConcertHall the lecturehall were scoredhigher than the other two rooms.There were Acoustics(Springer-Verlag, Berlin, 1985)]. Identified are the most impor- significantdifferences in the ratingsof the differentmusical pieces in all tant acousticalattributes to the rating scheme:RT, G, ITDG, IACC(E), and rooms. The ratings in the outdoor tests were consistently less than those in BR. Preferred values for each of these acoustical attributes is estimated all of the indoorlocations by over two scalepoints illustrating the impor- fromthe resultspresented in a companionpaper [Beranek, "Correlations tance of room effects. The ratings in the performingarts center for the betweencategories of acousticalquality and modem physical quantities"]. recordedmusic were significantlylower than ratingsobtained at the same Formulasare borrowed from the Ando studyand constants are chosenthat locationsby a groupof studentsevaluating live orchestralperformances in expressthe relativeimportance, and the degreeof falloff in contributionto theroom. [Work supported by NSF.] 3319 J. Acoust.Sec. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3319 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 11:15 11:30 3aAAll. Audibility of individual reflections in a complete sound 3aAA12. A preliminary analysisof image shifting in concert halls. field.II. S•renBech (Bangand Olufsen Ltd., Peter Bangs Vej 15,Street GilbertA. Soulodre (Dept.of Psych.,Carleton Univ., 1125Colonel By DK-7600, Denmark) Dr., Ottawa, ON K1S 5B6, Canada) This is a continuationof paperI, presentedat the Wallace Clement SabineCentennial Symposium in Boston1994. The thresholdof detection Under typical conditions,the early reflectionsin a concerthall are (TD) andjust noticeabledifference (jnd) for an increasein level was attenuatedrelative to the direct soundand are thusintegrated with the measuredfor six individualreflections in a completesound field. The directsound. However, there are instanceswhere, due to focusingeffects, subjectswere instructedto usechanges in timbreas the criteriafor detec- the level of a reflectioncan be greaterthan or equalto the level of the tion.The soundproduced by a singleloudspeaker in a normalsize listening direct sound.This can resultin an apparentshifting of the imageaway room was simulatedusing an electroacousticsetup. The simulatedloud- from the true sourceand towardthe sourceof the reflection.This paper speakerhad directivitycharacteristics according to the measuredcharac- reportson a seriesof subjectivetests designed to providean initial look at teristicsof a real loudspeakerand the room surfaceshad frequency- the parametersof the reflectedsound which influence image shifting. Tests dependentabsorption characteristics according to measurements.Values of wereconducted using two methods:binaural simulation and multiple loud- TD andjnd were measuredusing four subjectsfor noiseand speech.The results confirmed that the first-order floor reflection contributes individu- speakersin an anechoicchamber. Image shiftingwas examinedas a func- ally to the timbre of the soundfield. The resultshave furthershown that tion of the level, delay, angle of arrival, and spectralcontent of the re- energyin the frequencyrange 500-2 kHz is importantfor the TD level. flected sound relative to the direct sound. The results were examined in the The noiseand speechstimuli have been found to resultin significantly contextof the OrpheumTheatre in Vancouverwhere pronouncedimage different TD and jnd values for all reflections,and is contraryto the shiftingoccurs at certainlocations in the hall due to severallarge concave previousreported results. [Work financed by Eurekaproject EU105.] surfacesin the ceiling. THURSDAY MORNING, 1 JUNE 1995 MEETING ROOM 3, 7:45 TO 11:45 A.M. Session 3aEA EngineeringAcoustics and Noise: ElectromagneticCompatibility of AcousticalInstruments Victor Nedzelnitsky,Cochair National Institutefor Standardsand Technology,Sound Building 233, RoomA147, Gaithersburg,Maryland 20899-0001 Richard J. Peppin,Cochair Scantek,916 Gist Avenue,Silver Spring, Maryland 20910 Chair's Introduction--7:45 Invited Papers 7:50 3aEA1. Electromagneticinterference (EMI) concernsand electromagneticcompatibility (EMC) modelingfor acoustic instrumentation.David S. Dixon (ElectromagneticCompatibility Branch, Nay. UnderseaWarfare Ctr., New LondonDetachment, New London,CT 06320) Traditionally,the electromagneticinterference (EMI) concernsof submarineshave been dominated by the susceptibilityof low-frequencysubsystems associated with acoustic, control, and electromagnetic systems. The uniqueness of theefforts to ensurethe nondegradedoperation of thesesystems is thefact that the frequency range of thesusceptible systems and the typical EMI sources overlap.Therefore, many low-frequency, 1ow4amplitude signals can be degradedby low-frequencyconducted and radiatedEMI createdby thepower generation and distribution system. Power line rectification and switching harmonics are radiated magnetically aswell as conducted along cables, shields, and ground plane components. In addition, the use of modemwideband digital systems coupledwith theuse of lightweight,low-cost, nonmetallic enclosures has produced an additionalconcern caused by therapidly increasingradiated electric field environment. In summary, the electromagnetic environmental (E3) concerns associated with acoustic instrumentationin vcr• similar to theE 3 concernsthat are required for shipboard systems. This paper will discussthe typical EMI couplingmechanisms that will degradethe expectedperformance of low-frequencysystems, such as audiometers,acoustic instru- mentation,telephones, cabling, etc. In addition,it will discussthe EMI modelsthat have been developed for componentsas well as the latestanalysis and predictive EMC designtechniques that havebeen developed to achievecabinet and compartmental (room) compatibility. 8:15 3aEA2.Electromagnetic compatibility standards for acousticalinstruments. Ted Kuemmel (Quest Tech., 510 S. Worthington St., Oconomowoc,WI 53066) Thereis an increasingawareness of the problemscaused by interferencefrom electromagneticfields on electronicdevices. The rapidexpansion of the useof personalradio communication devices suggests a growing problem. The sophisticatedelectronic technologynow commonly used in acousticalinstruments is more susceptible to electromagnetic interference than previous technolo- 3320 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3320 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp gies.In 1991,the ANSI Committee SI, Acoustics,formed working group 21 to develop a new standard toaddress the radio frequency electromagneticsusceptibility of acoustical instrumentation. Now in itseighth draft, the standard provides general specifications forthe characteristicsof acoustical instruments when used in thepresence of radiatedelectromagnetic fields. The standard provides limits on allowabledeviation from specified acoustical performance based on theaccuracy class of theinstrument. The standard also presents minimumtesting requirements and sample test methods to demonstrateconformance to the specifications.Internationally, the IEC TechnicalCommittee 29, Electroacoustics,is also working on this problem. The current status of theseefforts and the issues driving then]are presentedand compared. 8:40 3aEA3. Electromagneticsusceptibility of soundlevel meters. Hans-O.Finke (Pfiysikalisch-TechnischeBundesanstalt, Bundesallee100, D-38116 Braunschweig, Germany) Testsof electromagneticsusceptibility (EMS) arepart of thetype of approvalprocedure for soundlevel meters in thefield of legal metrology.Starting in January1996 every electronic device on theEuropean market has to havea labelthat indicates a certification of the device,which also includesrequirements on electromagneticsusceptibility. The EMS test of soundlevel metersat the Physikalisch-TechnischeBundesanstalt (PTB) are performedin a radiofrequency anechoic chamber. The electricfield strengthis 6 V/m, the frequencyrange is 26-1000 MHz. The frequencyis variedin stepsof 4% and the signalis modulatedwith 1000 Hz (m=80%). An acousticalsignal is appliedto the soundlevel meterand the differenceof the displayedlevels with andwithout the electromagneticfield has .to be withinspecified tolerances (0.5 to 2 dB).At themoment not all typesof soundlevel meters comply with thesetolerances; with instrumentsunder test deviations up to 18 dB hadbeen observed. The presenttest procedure will be improved for futureregulations and standards (higher strength of field,wider frequency range, influence of accessories).Methods and results will be reported. 9:05 3aEA4. Electromagneticsusceptibility of audiometers. Utz Richter (Physikalisch-TechniscbeBundesanstalt, Lab. 1.51, Bundesallee100, D-38116 Braunschweig,Germany) As earlyas 1991the Physikalisch-Technische Bundesanstalt (PTB) in Germanydecided that tests of electromagneticsusceptibility haveto be performed,in general,with all measuringinstruments submitted to PTB for patternevaluation, among them also pure-tone and speechaudiometers. A largeshielded room is availablewhere electromagnetic fields (10 V/m, 10-935 MHz, l-kHz toneAM modulation)can be generated. No suitabletest method and no limits were found in anyknown standard for audiometersincluding IEC 645-1,and no availableacoustic measuring equipment did passthe EMC testby itself.So a newtest method had to bedeveloped based on loudnessbalance tests between the l-kHz-intefferencetone caused by the electromagneticfield andthe ordinary1-kHz testtone of the audiometer.The testsare performedin the shieldedroom at fixedcarrier frequencies. Taking into accountthe uncertaintyof this subjectivetest method,an upper limit of 60 dB HL for the interferencelevel was established.Of the first 25 types tested,92% audiometersdid fail the EM susceptibilitytest in the first run. All of thempassed the testafter reconstruction. 9:30 3aEA5. OIML standardson performancerequirements for acousticalinstruments. SamuelE. Chappell (Officeof Standards Services,NIST, Gaithersburg,MD 20899) The InternationalOrganization of LegalMetrology (OIML) is a treatyorganization, having currently 53 (voting)member and 40 (non-voting)member nations, most of the latternations being characterized as developing. OIML's objectiveis to harmonizenational regulationsfor the performancerequirements of legalmeasuring instruments among member nations in orderto facilitateinternational commerceof measuringinstruments and affected products, to ensurepublic health and safety, and to protectthe environment.This effort intendsto avoidor minimizetechnical barriers to internationaltrade. An OIML technicalcommittee or subcommitteedevelops OIML recommendations(standards or model performanceregulations) to addressparticular types or classesof instruments.If approved,member nations have a moralobligation to implementa recommendationin their national regulations for the instrument addressed.The obligationapplies both to new regulationand to harmonizingany existingregulations. This presentationaddresses OIML work projectsfor acousticalinstruments and the potentialimpact of relevantOIML recommendationson instrumentmanufac- turers.The basisfor requirementsincluding electromagnetic compatibility and the meansby whichthe UnitedStates participates in the work are covered. 9:55 3aEA6. Complicatedcases and shielded rooms: Audiometric booths shielded to attenuate electromagneticinterference (EMI). VictorNedzelnitsky (NIST, SoundBldg. 233, Rm. A147, Gaithersburg,MD 20899-0001) Electromagneticcompatibility (EMC) issuesinvolving acoustical instruments, especially their susceptibilityand immunityto electromagneticinterference (EMI), are increasingin importance.This increaseis drivingdomestic and internationalstandards development.Of particularsignificance is theimpact on commercialpractice and international trade of two Councilsof theEuropean Communitiesdirectives regarding generic apparatus (Council Directive 89/336/EEC, 3 May 1989) and medicaldevices (Council Directive 93/42/EEC, 14 June 1993). Directive 93/42/EEC is being interpretedto includehearing aids and audiometricinstruments. Numerousvoluntary International Electrotechnical, Commission (IEC) electroacoustic'alperformance standards are available for some of theseinstruments. However, extension of thesecomplicated standards to includeall pertinentEMC issuesis difficult.Development of standardsfor otherinstruments, such as thosefor measuringauditory brain-stem response, would be evenmore difficult. In some 3321 d. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3321 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp circumstances,theuse of shielded rooms toattenuate radiited EMI is practical andcost-effective. Inthe U.S.A., atleast, existing standardsfor measuringsuch shielded-room performance were not specifically developed for audiometricbooths. Methods in someof thesestandards have been adapted and applied to thatpurpose. Selected standards, methods, and someconsidei'ations regarding their applicationto measuringthe shieldingperformance of audiometricbooths in hospital/clinicalenvironments are discussed. ContributedPapers 10:20 terferenceto otherelectronic equipment. To insurethat the electricalequip- ment can work without influencefrom the electromagneticenvironment 3aEAY. Effect of electromagneticinterference on a continuouswave ultrasonicfield. David L. Cosnowskiand Mardi C. Hastings (Ohio andalso can operate without disturbing the environment, all electricequip- StateUniv., Dept. of Mech.Eng., 206 W 18thAve., Columbus, OH 43210) mentincluding acoustical measuring instruments sold within the Euiropean Communitymust fulfill the requirementsper EU50082- I and -2, startingI Continuous-waveultrasound for imagingand other measurementap- January1996. To achievethis goal a new specialtest laboratoryhas been plicationsrequires the use of a separatesource and receivertransducer. establishedat Bmel & Kjaer in Denmark. Here, all existing and new When this systemis used in air or water, the receivertransducer often measuringinstrumentation aretested for conformance toEIJ50082-1 and detectsa signalat the ultrasonicfrequency even in the absenceof a target. -2. The results have shown that a number of the existent instrumentation At ultrasonicfrequencies, significant electromagnetic coupling between the transducerscan occurdue to theirown andextraneous electromagnetic will haveto be modifiedor redesigned.The new Bruel & Kjaer FalconTM fields.This studyexamines the effect of this interferenceon the 3-dB rangeof measuringmicrophones, preamplifiers, and powersupplies has samplevolume defined by the crossedbeams. The samplevolume is de- beendesigned i n accordancewith the new requirements of EU50082-1 and terminedmathematically by modelingthe sourceand receivertransducers -2. This paper will describemeasurement results and give examplesof as planepiston radiators [J. Zemanek,J. Acoust.Sec. Am. 49, 181-191 experiencegained through this work. ( 1971)]. The effectof interferenceis obtainedby addinga constantterm to the samplevolume matrix, which, in general,is complex.Experimental measurementsusing an ultrasonicsource and receiver in air at several frequenciesfrom 40 to 100 kHz correlatewell with modelpredictions. The electromagneticinterference was found to havea significanteffect on the 10:50-11:00 Break observedfield. [Work supported by NSF GrantNo. MSS 9058607.] 10:35 3aEA8. New requirement for electromagnetic compatibility of i1:00-11:4• acoust'calinstrumentation. ErnstSchonthal and Helge Larsen (Bruel & Kjaer Instruments,Inc., Denmark) Most electronicequipment is sensitiveto electromagneticsignals. Of- PAN!•LDISCUSSION ten electronicequipment also radiates electromagnetic signals causing in- THURSDAY MORNING, 1 JUNE 1995 MEETING ROOM 2, 8:30 A.M. TO 12:00 NOON Session 3aNS NOise:State of the Art--Noise Effectsand Control Henning E. yon Gierke, Cochair Medical ResearchLaboratory, Armstrong Aerospace, AL/CF 2610 SeventhStreet, Wright Patterson Air ForceBase, Ohio 45433-7901 Daniel L. Johnson, Cochair BiophysicalOperations, EG&G SpecialProjects, P.O. Box 9100, Albuquerque,New Mexico 87119 Chair's lnt•.uction--8:30 Invited Papers 8:35 3aNSI.Noise environments outdoors andthe effects ofcommunity exposure. Edgar A.G. Shaw ilnst. for Microstructural Sci., Natl. Res. Council.Ottawa, ON KIA 0R6, Canada) Man-madenoise, especially transportation noise, creates acoustical environments that are vasdy different from those associated with pristinehabitats. During the past 25 years,the day-nightaverage sound level, L,•, hasgained substantial acceptance as a valid measureof themagnitude of anygiven pattern of communitynoise, taking into account its complextemporal and spectral charac- teristics.During the same period, the effects of variouslevels of noiseexposure on humanactivities and well-being have been widely studied.Data from manysocial surveys have been brought together and analyzedto clarify the relationshipbetween noise level and the prevalenceof annoyancewhich provides a broadindication of the impactof intrusivenoise on humancommunities. Criteria based 3322 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt.2, May1995 129thMeeting: Acoustical Society of America 3322 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp on suchstudies are now widely used in urbanplanning. In recentyears, there have been impressive reductions in the noiseemissions fromcommercial aircraft and notable improvements in the control of airportnoise, while highway barriers now provide some relief from motorvehicle noise. Finally, the potentialeffects of noiseon wildlife, especiallyendangered species, now comeunder close scrutinywhen majorprojects are plannedin remoteareas. 8:55 3aNS2.Occupational noise exposures: Where do we standtoday? AliceH. Suter (AliceSuter and Assoc., 575 DogwoodWay, Ashland,OR 97520)and DanielL. Johnson(EG&G Special Projects, P.O. Box 9100, Albuquerque, NM 87119) Therehave been several major improvements in the fieldof occupationalnoise exposure over the last 25 years.ISO 1999has been revisedand now providesan acceptedmethod of relatinghearing loss to noiseexposure. Hearing protection devices have been improvedconsiderably, impulse noise is beingassessed more effectively, and therehas been a shiftamong U.S. agenciestoward using the equal-energyrule in noiseexposure standards. Perhaps the mostimportant advancement has occurred with the promulgationof OSHA's hearingconservation amendment to its noisestandard. The future,however, poses many challenges: OSHA's noisestandard needsrevision, more emphasis on enforcementis needed,engineering controls should be re-emphasizedafter many years of inatten- tion, and totalreliance on hearingprotection devices should be de-emphasized.In addition,the benefitsof the hearingconservation amendmentneed to beextended to currentlyunderserved workers, such as miners and workers in construction,agriculture, and the oil and gasindustries. Perhaps the greatestchallenge is the needto investigatethe effectivenessof hearingconservation programs on a nationalscale to determinethe extentto whichthey are actuallypreventing hearing loss. 9:15 3aNS3. Noiseenvironments and their effects,Recreational exposures. Alf Axelsson (Hear.Res. Lab., LindholmenDev., Box 8714, S-402 75, Goteborg,Sweden) Many effortshave been made lately to combatoccupational noise exposure, and the situationin manyindustries concerning noise preventivemeasures seems promising. Conversely, with regardto recreationalactivities the situationseems less promising. There ave reasonsto raiseconcerns about noisy activities such as personal cassette players (PCPs), pop/rock concerts, car stereos, motor sport, shootingactivities, etc. For mostof the musicallyoriented activities the situation is probablygenerally satisfactory; even if thesound levelsfrequently are very high,the exposure time andnumber of exposures/yearis limited. For impulsivenoisy activities the situation is moreserious. As is well known,the impulsive noise in connectionwith theuse of weapons,fire-crackers, and toy-cap guns without hearingprotection may lead to a permanentnoise induced hearing loss under accidental conditions. The generalattitude concerning recreationalnoisy activities should obviously be to strivefor lowersound levels, limited exposure, and better use of hearingprotection. 9:35 3aNS4. Aircraft noisecontrol. David G. Stephens(Fluid Mech. andAcoust. Div., NASA-LangleyRes. Ctr., Hampton,VA 23681-0001) The purposeof this paperis to describethe researchprogram in aircraftacoustics being conducted by the NASA-Langley ResearchCenter. The programincludes research to understand,predict, and reduce the sourcesof aircraftnoise; to quantifythe transmissionof noisethrough the atmosphere and/or aircraft structures; and to definethe effects of noiseon people and structures. The researchis focusedon a broadrange of aircraftwith emphasison advancedsubsonic transports including conventional and tiltrotor rotorcraft,supersonic transports, high-performance military vehicles and hypersonic configurations. Specialty areas of researchinclude computationalaeroacousties, jet noise, rotating blade acoustics, and structural and subjective acoustics. The resultingtechnology is usedto designand operate aircraft to reducecommunity noise impact and/or to minimizethe effectsof noiseon structuralintegrity and interior noise. 9:55 3aNSS.Advances in noisecontrol for productsother than aircraft. WilliamW. Lang (Phys.Dept., Box 539, VassarCollege, Poughkeepsie,NY 12601) Howmuch progress has been made in advancingthe technology of noisecontrol over the past quarter century? Different techniques of quietinghave been applied to the many products that are grouped in thefollowing broad categories: stationary noise sources, moving noisesources (other than aircraft), and specialized industrial machinery and equipment. For all products,the control of noiseby engineeringdesign is thegoal. To arrive at estimatesof progress,two subsidiary questions must be addressed. How is progresstobe measuredin quantitativeterms? Recognizing that trade secrets and patented innovations may be involved,how is it possibleto learn whatprogress has been made for thedifferent classes of products?A key factoris thatchanges in functionaltechnology may reduce the noiseemissions as a desirableby-product; for example,ink-jet and laser printers are muchquieter than impact printers. The estimatesof progressin productquieting in termsof thereductions ofA-weighted sound power levels range from 0 dBfor leafblowers up to 50 dB for deviceswhich 25 yearsago required cooling fans for theirsafe and efficient operation, but today require none. 3323 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3323 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 10:15-10:25 Break 10:25 3aNS6. Twenty-fiveyears of progressin noisestandardization. Paul D. Schomer (U.S. Army ConstructionEng. Res. Lab., Champaign,IL 61826-9005) This paperdocuments the morethan ten-fold growth in the numberof Standardsand the programof workcarried out by theASA Standardsdirectorate for the AmericanNational StandardsInstitute (ANSI) and for relatedinternational work with the International Organizationfor Standardization(ISO) and the InternationalElectro-technical Commission (IEC). Not only hasthere been a huge increasein the workeffort, but theemphasis has changed greatly. Now we work to ensurethat [SO Standardsare fair to all players and to ensurethat ANSI Standardsare compatiblewith ISO. While majorU.S. industriesaxe participating in this effort, more participationis neededby industryand government.Case histories are usedto showhow our effortsin the standardsprocess are currentlyhelping some U.S. manufacturersto markettheir products worldwide. Major industrieswith somesignificant involvement includeautomotive. construction and agricultural equipment, computer and businessmachines, hearing conservation equipment, and audiologicaltesting, and sirensand alarms.Many otherindustries such as aircraft,mining, rotating electrical machinery, and manu- facturersof acousticalmaterials, attenuators, mufflers, and soundproofenclosures currently lack significantinvolvement in the ISO process.Thus greater involvement is requiredby significantsectors of U.S. industry. 10:45 3aNS7. Federal regulationsand governmentactivities in noisecontrol. R.L. Miller (Harris,Miller, Miller & Hanson,Inc., 15 New EnglandExec. Park, Burlington, MA 01803) Sincethe demiseof the EPA'sOffice of NoiseAbatement and Controlat the handsof formerPresident Reagan, coordinated regulatoryaction for thecontrol of noiseat theFederal level has essentially disappeared. Instead, governmental agencies are left to deal with theirnoise problems on theirown, usually meaning that they respond only to specificlegislation, political pressures, or litigation. Agencycoordination, when it doesoccur, is imposedby ExecutiveOrder or law.This paperbriefly reviews existing Federal regulations controllingthe world of transportationnoise, but focusesto a greaterextent on the on-goingefforts of our govemmentthat will influenceour noiseenvironment into the next century.The papersummarizes the actionsof the FederalAviation Administration, the NationalAeronautics and Space Administration, and the Departmentof Defenseas theyconfront issues of aircraftnoise and airspace management;the NationalPark Serviceas it strugglesto resolveconflicting mandates to preservenatural quiet and solitudewhile providingaccess to and publicenjoyment of NationalParks and Forests;the FederalRailroad Administration and the FederalTransit Administrationin their endeavorsto controlnoise from transit,high-speed rail, and mag-levsystems; and the FederalHighway Administrationas it developsbetter tools to assessand control the noiseimpact of traffic.The paperconcludes, speculating on the effectsthat reduced Federal spending will haveon theseefforts. 11:05 3aNSS.A globalvision for thenoise control marketplace. Bennett M. Brooks (BrooksAcoust. Corp.. 27 HartfordTnpke., Vernon, CT 06066), T. JamesDuBois (Aeentech,Canoga Park, CA 91303), RobertM. Hoover (Hooverand Keith, Inc., Houston,TX 77082), GeorgeC. Maling (EmpireState Software Systems, Ltd., Poughkeepsie,NY 12603),and LouisC. Sutherland(Rancho PalosVerdes, CA 90274) Muchprogress has been made over the past 25 yearsin the UnitedStates to definethe dangers of excessivenoise exposure, and to developthe meansto controlit. A significantportion of this progresswas stimulatedby governmentactions, to regulatethe industrieswhich produce noise, establish community and workplace noise standards, and to promoteresearch and development in noisecontrol. Today, the pressures of competitionin theglobal marketplace, which did not exist 25 yearsago, are rapidly increasing the motivationfor noisecontrol in the privatesector. Those industries which seek to selltheft products worldwide, particularly in Europeor Japan,find that they must meet stricter standards than now exist in theU.S. Further, foreign companies which already live with stricterstandards are producing quiet products that compete for salesin theU.S. These challenges present both a threatand an opportunityto the U.S. economy.Several actions which can be immediatelytaken to addressthese issues are suggested. 11:25-11:55 PANEL DISCUSSION 11:55-12:00 CONCLUSION 3324 J. Acoust.Soc. Am., Vol. 97, No.5, Pt.2, May1995 129thMeeting: Acoustical Society of America 3324 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp THURSDAY MORNING, 1 JUNE 1995 CONGRESSIONAL HALL B, 8:00 A.M. TO 12:05 P.M. Session 3aPA PhysicalAcoustics: Ultrasonic Techniques Inder Raj S. Makin, Chair Departmentof Engineering,Swarthmore College, Swarthmore, Pennsylvania 19081-1397 Chair's Introduction-•8:00 ContributedPapers 8:05 8:35 3aPAI. Acoustic radiation pressure in an infinite !ossy medium. 3aPA3. The use of high-intensityfocused ultrasound for noninvasive Zhong-YueJiang and James F. Greenleaf(Dept. of Physiol.and Biophys., surgery. LawrenceA. Crum (Appl.Phys. Lab., 1013NE 40th St., Univ. Mayo Clinic andFoundation, Rochester, MN 55905) of Washington,Seattle, WA 98105) and Wing Law (FocusSurgery, Fremont,CA 94539) Theorieson acousticradiation pressure associated with plane acoustic wavesand losslessmedia have beenexamined extensively. The radiation High-intensityfocused ultrasound (HIFU) canbe usedto destroytissue pressureproduced by a non-planewave in a lossyunbounded medium was in vivo; recentapplications of this modality to the treatmentof benign analyzed.The distinctionbetween Lagrangian and Eulerian pressurewas usedto clarify the understandingof radiationpressure. The radiationpres- prostatichypertrophy (BPH) havemet with significantsuccess. The lesions sure exertedon a perfectly absorbingpointwise target by an arbitrary formed by focusedultrasound can be inducedby both thermaland me- acousticwave in an unboundedIossy medium was then considered.By chanical(cavitation) mechanisms. However, the relative contributionsof usingan indirectapproach developed in Chuand Apfel [B.-T. Chuand R. thesetwo mechanisms,under varied HIFU parameters,are oftendifficult E Apfel,J. Acoust.Soc. Am. 72, 1673-1687(1982)], the radiation pres- to ascertain.Descriptions are presentedof somesimple experiments de- surewas analyzedwithout appealing to the detailedsolutions of the gov- signedto elucidatethe relativeroles of cavitationand thermal effects in erningfluid dynamic equations. It wasshown that even in Iossymedia with specifictissues; these tests were undertakenin turkeybreast tissues, but arbitrarywaves, the radiationpressure experienced by a pointwisetarget is seem to correlatewell with previousin vivo experimentsin dogs and equalto theLangevin pressure which is thetime average energy density at humans.The experimentsindicate that cavitation,once induced, tends to that point.The radiationpressure exerted on a specifictarget by an arbi- shortenand broadenthe thermallyinduced lesions, suggesting that the traryacoustic wave in an infiniteIossy medium was studiedand a concise presenceof free gas generatedby the cavitationblocks passage of the theoreticalresult was obtained. [The work was supportedby grantsCA ultrasound. 43920 andHL 41046 from the NationalInstitutes of Health.] 8:20 8:50 3aPA2. Simulation of ultrasonic propagation through abdominal 3aPA4. Measurementsof finite-amplitudeacoustic pulses radiated wall. T. DouglasMast, Laura M. Hinkelman,Robert C. Waag (Dept.of from focused piston sources in water. Michalakis A. Averkiou, Elec. Eng., Univ. of Rochester,Rochester, NY 14627),and VictorW. LawrenceA. Crum (Appl. Phys.Lab., Univ. of Washington,Seattle, WA Sparrow (PennState Univ., University Park, PA 16802) 98105), and Mark F. Hamilton (Univ. of Texasat Austin,Austin, TX 78712-1063) Ultrasonicpulse propagation through the humanabdominal wall is simulatedusing a modelfor two-dimensionalpropagation through ana- Measurementsof finite-amplitudeacoustic pulses radiated by a focused tomicallyrealistic tissue cross sections. The time-domainwave equation pistonsource in waterare reported. Pulses with centerfrequency of 2.25 for a mediumof variablesound speed and density is discretizedand solved MHz, durationsranging from two to tencycles, and peak sound pressures as a setof coupledfinite-difference equations. The finite-differencealgo- up to 3 MPa weremeasured with a wideband(1-20 MHz) membrane rithmused is a two-stepMacCormack scheme that is fourth-orderaccurate hydrophone.The combinedeffects of focusing,diffraction, and finite- in spaceand second-order accurate in time.The inhomogeneoustissue of amplitudedistortion on shortpulses are demonstrated. Propagation curves the abdominalwall is representedby two-dimensionalmatrices of sound for the peakpositive and peak negativepressure along the axis of the speedand densityvalues. These valuesare determinedby mapping sourceare shown. The peaknegative pressure, which is an importantfactor scannedimages of abdominalwall crosssections that have been stained to in cavitationdynamics, is maximizedin the prefocalregion and shifts identifyconnective tissue, muscle, and fat, each of which is assumedto havea constantsound speed and density. The computationalconfiguration closerto the sourcewith increasingsource amplitude, as predictedearlier is chosento simulatethe experimentalwave-front distortion measurements [Avcrkiouct at., J. Acouat.Soc. Am. 96, 3306(A) (1993)].Tissue image• of Hinkelmanet al. [J.Acoust. Soc. Am. 95, 530-541 (1994)].Qualitative duringtreatment with a therapeuticultrasound device that show increased agreementis foundbetween those measurements and the resultsof the cavitationactivity in the prefocalregion are presented.The measurements presentcomputations. Visualization of calculatedsound fields is usedto arecompared with theoretical predictions based on theKZK equationand illustrate the salient characteristics of ultrasonic wave-front distortion in goodagreement is found.[Work supported by the NationalInstitutes of vivo. Health.] 3325 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3325 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 9:05 9:50-10:05 Break 3aPAS.Magnetic field studiesof the superconductingtransition in (Lat_xSr•)aCuO4 singlecrystal by ultrasonicmeasurements. M.J. McKenna,Hong Zhang, Bimal K. Sarma,Moises Levy (Dept.of Phys., 10:0s Univ. of Wisconsin--Milwaukee,Milwaukee WI 53201), T. Kimura, K. 3aPAS. Temperature rise generated by diagnostic ultrasound in a Kishio,and K. Kitazawa (Univ.of Tokyo,Tokyo, Japan) transcranialphantom. JuntoWu, FrancesCubberiey, Gerard Gormley (Dept.of Phys.,Univ. of Vermont,Burlington, VT 05405),and Thomas The temperaturedependence of theultrasonic attenuation and the rela- L. Szabo (Hewlett-PackardImaging Systems, Andover, MA 01810) tivesound velocity were measured in a singlecrystal of (La• zSrx)2CuO4 (x=0.075, nominal) with dimensions ofabout 4)<4)<4 mm 3, in a tempera- Temperaturerises generated by diagnosticultrasound from a commer- turerange of 4.2 to 50 K. The superconductingtransition of thissample cial system(Sones 1000 Hewlett-Packard) in a transcranialphantom that measuredby ac susceptibilityis at 36.6 K. The frequencyof longitudinal consistsof humantemporal bone and tissue-mimicking material are mea- soundwaves propagating along the c axiswas extended up to 305 MHz. sured.Significant temperature rises were found at theexternal and internal The attenuationshows two peaks,one at about27 K and the other at temporalbone surfaces.. The experimentalresults are compared with Cra- around36.7 K, while the soundvelocity exhibits softenlugs of about20 nialThermal Indices (TIC) developedby AmericanInstitute of Ultrasound in Medicine and National Electrical Manufacturers association in 1992 for and 80 ppm at the correspondingtemperatures, respectively. Magnetic fieldsof 11 KOe wereapplied in the a-b planeto studythe effectsof the variousmodes. For all the modescompared, TIC underestimatedtempera- turerise at the externaltemporal bone surface. The differencesbetween the field on boththe temperaturesand the heightsof thesefeatures in attenu- dataand temperature rises predicted by TIC canbe attributedto transducer ation and velocity.The results,combined with the frequencydependences surfaceheating. [Work supported by Hewlett-PackardCo.] of thesefeatures, suggest that the transitionat 36.7 K may possiblybe producedby botha structuraltransition and the superconducting transition. In addition,results on the temperaturedependence of the attenuationupon coolingin magneticfields will bepresented. [Work supported by the Office 10:20 of Naval Research.] 3aPA9. Numerical anomalies in the Rayleigh-Ritz method for calculatingthe normal mode vibrationsof arbitrarily shapedelastic solids. P.S. Spoorand 1. D. Maynard (Dept.of Phys.,Penn State Univ., UniversityPark, PA 16802) 9:20 A matriximplementation of theRayleigh-Ritz variational method was 3aPA6. Pressure and cavitation measurements of an intra-arterial usedby Demarest[H. H. Demarest,1. Acoust.Sec. Am. 57, 768] to make angioplastydevice. InderRaj S. Makin andE. Cart Everbach(Dept. of the first successfulcalculation of the eigenfrequenciesand eigenmodesof an isotropicelastic cube, and was later generalized by Ohno[I. Ohno,J. Eng., SwarthmoreCollege, Swarthmore, PA 19081-1397) Phys.Earth 57, 355] andVisscher [W. M. Visscheret al., 1. Acoust.See. Am. 90, 2154-2162 (1991)] to applyto solidsof arbitraryshape and Variationof the acousticfield radiatedfrom a low-frequency(22.5 elasticsymmetry. This becamethe core of a newmethod of elasticconstant kHz) catheterlikeangioplasty device in a relativelylarge (600 L) tankof determinationbased on measurementsof the normalmode spectra of elas- waterwas presented earlier [I. R. S. Makinand E. C. Everbach,J. Acoust. tic parallelepipedsand spheres,called resonantultrasound spectroscopy Sec.Am. 95, 2855(A) (1994)].The normalvolume of the humantorso or (RUS).In theory,one should be ableto useRayleigh-Ritz to determinethe the human limb into which the ultrasonicwire is insertedduring therapy effectof imperfectparallelepipeds (due to smallerrors in sampleprepara- cannot be treated, however, as an infinite medium for the 66.6-mm wave- tion) on the accuracyof RUS. It has beendiscovered, however, that the length(calculated for water)due to the wire source.Therefore the sound methodmay not convergeproperly for many relevantcases, producing fieldof thedevice was investigated in a liquid-filledPlexiglas © cylinder spuriousresults. A variety of examples,including comparisons with low- (200-mm diameter,350-mm height)to simulateanthropometric dimen- orderapproximations, will be discussed.[Work supportedby NSF Grant sions.Measurement of pressuresalong the axis of thecylinder for the wire DMR-9000549and by the Officeof Naval Research.] sourcepositioned axially at oneend of the cylindershows a markedstand- ing wave patterneven up to an axial range of 250 ram. Such strong standingwaves could potentially exist far awayfrom theprobe tip in vive. In addition,the occurrenceof cavitationat the tip of the wire was con- 10:35 finnedusing a 20-MHz passivecavitation detection technique. 3aPA10. Ultrasoniccharacterization of the quality of an epoxy resin. B. Faiz, A. Moudden (Lab. d'Instrum.et de Mesures,Facult6 des Sci. d'Agadir, Univ. tbnou Zohr, Agadir, Morocco), D. Drcultot, and G. Maze (Universit6du Havre, Le Havre,France) 9:35 A pulseultrasonic technique has been developed to studythe quality of the liquid/solidtransformation of an epoxyresin made up of two compo- 3aPA7. Correction of errors in Doppler peak velocity measurements nents(resin and hardener). The epoxyresin is in a tankwith parallel faces. made with commercial ultrasound systems. Andrew J. Winklet and A reflectiontechnique allows the measurementof the phasevelocity, the JunruWu (Dept. of Phya_,Univ_ of Vermont,]•urlln•ton, VT 05405) attenuanon,and the acousticalimpedance. The firstand secondparameters give an averagestate of the resinhardening in the thickness.The temporal CommercialDuplex ultrasoundsystems primarily measure peak veloc- evolutionof the lastparameter allows an evaluationof the stateof the resin ity of blood flow to provideinformation in diagnosingvascular disease. at the interfaceresin/tank wall. Theseexperiments have been achieved for However,due to errorscaused by intrinsicspectral broadening (ISB), the differentproportions of the hardener.The velocity and the attenuation accuracydecreases as Doppler angleincreases. In general,vascular tech- increase at first and then stabilize after a time which is as short as the nologistskeep the Doppler angle under 60 ø. Sincemost vessels in thebody hardenerconcentration is high. The experimentshows that 10% of the run almostparallel with the skin surface,any criteriarequiting a Doppler hardeneris the optimumvalue and that 20% of it producesa vitreous angleof say45 ø or lesswould be difficultto achieve.Using the transverse transition.The experimentalresults also show that the acousticalimped- Dopplerequation [Newhouse et al., I. Acoust.Sec. Am. 95, 2091-2098 ancestabilizes after a time longerthan the oneobserved for the velocity (1984)]as a correctionfor ISB, in cojancfionwith the classical Doppler and the attenuation.The velocityand the attenuationare significantpa- equation,much more accuratepeak velocitymeasurements were obtained rametersof the optimumvalue of the hardenerconcentration. The acous- at Dopplerangle as high as 80ø . tical impedanceis the significantparameter of the bondquality. 3326 J. Acoust.Soc. Am., Vol.97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3326 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 10:50 examinedwhich has potential advantages for theinvestigation of thisclass of mediatedinteractions of soundwith sound.The new geometryuses a 3aPA11.Polarimetric fiber-optic ultrasonic sensor for the high-frequencyprobe beam that is collinearwith the axis of the pump nondestructiveevaluation of materials. ChonghuaZhou, StephenV. standingwave. The Braggsignal for thisgeometry is amenableto analysis Letcher (Dept.of Phys.,Univ. of RhodeIsland, Kingston, RI 02881), and with transfermatrices, The interactioninvestigated has potentialapplica- N. Narendran (MTI, Latham,NY 12110) tionsto the acousticalprobing of suspensions.[Work supported by the A fiber-opticpolarimetric interferometer has been used as an ultrasonic Officeof NavalResearch.] sensorin a feasibilitystudy of flaw detectionand nondestructive evaluation of materials. The sensor is based on acoustic modulation of the birefrin- 11:35 genceof a polarization-maintainingfiber. The smallsize of the fiberand the ability to embedit in materialsprovide significantadvantages over 3aPA14. Greenspanacoustic viscometer: Recent results. Keith A. conventionaltransducers. When the fiberand sample are bothimmersed in Gillis,Michael R. Moldover (NIST,Thermophys. Div., Gaithersburg,MD water,sample thickness and flaw location,size, and orientation have been 20899), and James B. Mehl (Univ. of Delaware, Newark, DE evaluated.The fiber has also beenembedded in a Plexiglasspecimen and 19716-2570) hasshown the potential to locateinternal flaws. [Work supported, in part, Acoustic resonatorsconsisting of a duct coupling two cavities by NSF.] (Greenspanviscometers) have a low-frequencymode whose response is a sensitivefunction of theviscous diffusivity of theenclosed gas. The re- 11:05 sponsefunction is determinedexperimentally by measuringthe acoustic pressurein one cavityas a functionof the frequencyof a sourcein the 3aPA12. Concentration, fractionation, and separation of small other cavity. A theoreticalresponse function, based on a model which particles in liquid by ultrasound. Kenji Yasuda, Shin•ichiro includesviscous and thermalboundary layer phenomenain both the duct Umemura (Advanced Res. Lab., Hitachi Ltd., 2520 Akanuma, and the cavities, as well as inertial and resistiveduct-end corrections, is fit Hatoyama-chou,Hiki-Gun, Saitama 350-03, Japan), and KazuoTakeda to the data to determinethe viscousdiffusivity. Recent measurements in (CentralResearch Lab., HitachiLtd., Tokyo 185,Japan) argon,helium, and propane near room temperature span a rangeof viscous The efficacyof usingan ultrasonicstanding plane wave to concentrate diffusivityfrom 7 X 10-7 to2 X [0-4 m/s2. Experimental values determined smallparticles in a liquid was theoreticallyestimated and comparedwith with threedifferent viscometers differ from referencevalues by average exper/mentalresults. Acoustic energy density was measuredby ultrasonic valuesof 2.7% (viscometer0), 0.8% (viscometer1), and 1.8%(viscometer absorption,and particle distribution was observed by darkfieldmicroscopy. 2). [Worksupported by theOffice of NavolResearch.] The theorypredicts that the effectof diffusionis negligiblein concentrat4 ing polystyrenespheres larger than 5/xm in diameterwhen they are sub- 11:50 jectedto 4 J/m3 ultrasoundat500 kHz. The half-width of thesteady-state particledistribution in theexperiment was of the sameorder of magnitude 3aPA15. Numerical investigationsof double-Helmholtz resonators as that of the theory.This concentratingtechnique was applied to the and duct-endeffects. JamesB. Mehl (Dept.of Phys.and Astron., Univ. fractionationof polystyrenespheres l0/•m in diameterby usinga capillary of DelawarelNewark, DE 19716-2570and NIST Gaithersburg,MD tube.More than90% of the particlesin a laminarflow were successfully 20899) collected.A separationtechnique based on the competitionbetween the acoustic radiation force and the electrostatic force was also tested. A mix- The acousticfields and eigenfrequenciesof doubleHelmholtz resona- tors(Greenspan viscometers) have beeninvestigated using a boundary- ture of polystyrenespheres with two differentradii, which lined up on a integral-equationtechnique. The resonatorgeometry consists of a circular pressurenode of a stationarystanding wave, was successfullyseparated duct connectedat both ends to concentriccylindrical cavities.Compari- accordingto theirradii by applyinga uniformelectrostatic force parallel to the acoustic radiation force. sonsof the numericallydetermined fields with analyticexpressions based on a Green'sfunction expansion establish the high accuracy of themethod. The acousticflow near the duct-cavityorifices has the expectedsingular 11:20 behaviorat theedge of theduct orifice. The associatedduct-end inertance correspondsto a lengthcorrection of approximately0.82 timesthe duct 3aPA13. Collinear ultrasonic four-wave mixing mediated by a radii,slightly smaller than the classical formulas of Rayleighand Ingard [1. suspension.Christopher S,Kwiatkow, skiand Philip L. Marston(Dept. Acoust.Soc. Am. 25, 1037-1061 (1953)], whichare basedon an assumed of Phys.,Washington State Univ., PullMan, WA 99164-2814) uniform(piston) flow within the orifice. Numerical integrations of the In previouswork, ultrasonicfour-wave mixing mediated by a suspen- squareof the tangentialparticle velocity over the wallsof theduct and the sionwas bbserved by obliqueBragg reflection of a high-frequencyprobe cavitywall surroundingthe orifice have been used to estimatethe orifice wavefrom a periodicgrating [H. J. Simpsonand P. L. Marston,J. Acoust. resistance.This quantity was found to correspondto a resistanceeffective Soc.Am. 90, 2244(A)(1991)]. The grating in thenumber density of sus- lengthof approximately0.79 times the viscous penetration length, a result pendedpolymer microspheres was induced by theradiation pressure of a of importancein the modeling of Greenspanviscometers. [Work supported standingpump wave. In the presentinvestigation, a differentgeometry is by theOffice of NavalResearch.] 3327 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3327 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp THURSDAY MORNING, I JUNE 1995 GRAND BALLROOM CENTRAL, 7:45 A.M. TO 12:00 NOON Session 3aPP Psychologicaland PhysiologicalAcoustics: Pitch and Temporal Perception;Auditory Detection William A. Yost, Chair ParrelyHearing Institute, Loyola UniversiCy, 6525 North SheridanDrive, Chicago,Illinois 60626 ContributedPapers 7:45 to havea lowpitch corresponding t9 fo, whosediscriminability decreases asthe modulation offcam is shiftedfrom AM to QFM phaseIS. Greenberg 3aPPI. Pitch and pitch strength of iterated rippled noise. William andP. L. Divenyi,Proc. 18th Midwinter Mtg. ARO, p. 55 (1995)].In the A. Yost,Sandra J. Guzman,and Stanley Sheft (ParrelyHear. Inst., Loyola presentexperiments, pitch discrimination was measured for pairsof CAM Univ.Chicago, 6525 N. SheridanRd., Chicago,IL 60626) toneshaving fixed f0 differencesbut either variable depth (1%-200%) or A cascadeof add,delay (d ms),and attenuate (-l• 8:15 The oppositionbetween "place" and "time" perspectivesin auditory functionfinds its fullest theoreticalexpression in the long-standingcon- 3aPP3. Trade-off between depth and phase of modulation in the troverayover the neuralbasis of pitch.Traditionally, the two perspectives perceptionof pitch of complexamplitude-modulated tones. Pierre have been viewed as mutuallyexclusive, with pitch derivedfrom either L. Divenyi (Speechand Hear.Res., V.A. MedicalCenter, Martinez, CA placeor temporalcues, but not both.The controversypersists, in largepart, 94553), StevenGreenberg (Univ. of California,Berkeley, CA 94720), becauseneither perspective, by itself, can fully accountfor the full range and Alain P. Algazi (V.A. MedicalCtr., Martinez,CA 94553) of perceptualexperience associated with the pitchof complexsignals [E. Complexamplitude-modulated (CAM) toneswere generated through F. Evans,Audiology 17, 369-420 0978)]. It is proposedthat pitch stems amplitudemodulating a high-frequency carrier fcam (3-10 kHz) by anAM from the interplayof place and time information,bound together into a tonehaving a mr,rdulati.g frequency and a carrier cf•L•out i0% offc•t coherentrepresentation through the operationof central coincidence- modulatedat a ratefo in the 100-Hz range.CAM soundshave beenshown sensitiveneural populations. This frameworkprovides a principledbasis 3328 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3328 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp for understandingthe neuralmechanisms underlying the majorproperties Performanceat the unexpectedrates depended upon the targetrate. For the of pitch(such as the "dominance"and "existence" regions, the first and 4-Hz target,modulation at all rateswas detected on about80% of thetrials. secondeffects of/he pitchshift, phase-insensitivityand dichoticallyme- For the32- and256-Hz targets,unexpected modulation rates of 16 Itz and diatedpitch] and illustrates the manner in whichboth frequency selectivity above were detectedon 80%-90% of the trials, but modulation rates below and synchronyare requiredfor computinga signal'speriodicity with pre- 16 Hz weredetected nearly at chance.Thus, contrary to the predictionsof cisionand reliability. severalpopular models, the abilityto detectmodulation was clearly influ- encedby expectationof themodulation rate. [Work supported by NIH.] 9:00 3aPP6. The effects on comodulation masking release (CMR) of systematicvariations in on- and off-frequency masker modulation 9:45-10:00 Break patterns. Emily Bussand Virginia M. Richards (Dept.of Psych.,Univ. of Pennsylvania,Philadelphia, PA 19104) Detectionthresholds were obtained for a 500-Hz tonesignal added to 10:00 a maskercomprised of an amplitudemodulated tone centered at thesignal frequency(on-frequency masker) and an arrayof amplitudemodulated 3aPP9. Detectionof decrementsand incrementsin sinnsoidsat high tonescentered at 300, 700, 800, 900, 1000,and l100 Hz (off-frequency overall levels. Brian C. J. Moore (Dept. of Exp. Psych.,Univ. of maskers}.The on-frequencymasker was a sinustidallyamplitude modu- Cambridge,Downing St., CambridgeCB2 3EB, England}, RobertW. latedtone, and the off-frequencymaskers were square-wavemodulated Peters (Univ. of North Carolina,Chapel Hill, NC 27599-7190),and tones.On- andoff-frequency modulators were either in-phase or of random BrianR. Glasberg (Univ. of Cambridge,Cambridge, England) phaserelative to one another,and differentconditions used square wave modulatorswith different duty cycles (0%-100%}. The differencebetween Thresholdsfor the detectionof decrementsin level of sinusoidalsig- thresholdsobtained in the in-phaseand randomphase conditions (CMRs) nalswere measured as a functionof duration(2, 4, 6, 10, and 14 ms),level were as large as 12 dB, comparableto the CMRs foundwith perfectly (70, 80, and90 dB SPL) and frequency(250, 500, 1000,2000, and4000 matchedmodulators. Thresholds in the randomphase condition did not Hz). Sevennormally hearing listeners were testedat each frequency. dependon dutycycle, but for the in-phasecondition the plot of thresholds Thresholdsfor detectinga 10-msincrement in level were also measured. asa functionof dutycycle is "U" shaped.The dataare in roughagreement The sinusoldswere presentedin a backgroundnoise intendedto mask with "cued-listening"models of CMR in whichthe detectionof the added spectralsplatter associated with the decrementor increment.Performance toneis enhancedby thecue provided by theoff-frequency masker minima. improvedwith increasingfrequency for all decrementand incrementdu- [Worksupported by NIH.] rations.Performance also tendedto improvewith increasinglevel at 2000 and 4000 Hz. The resultswere analyzedusing a four-stagemodel consist- ing of an auditoryfilter, a nonlinearity,a slidingtemporal integrator, and a 9:15 decision mechanism.The analysis indicated that the improved perfor- 3aPP7. Mixed modulation masking: AM masking FM and FM mancewith increasingfrequency and increasinglevel can be attributed maskingAM. BrentW. Edwardsand Neal E Viemeister (Dept. of mainlyto changesin the detectionprocess following the temporalintegra- Psych.,Univ. of Minnesota,Minneapolis, MN 55455} torrather than changes in theequivalent rectangular duration (ERD) of the temporalintegrator. The ERD variedlittle with changesin frequencyand In a seriesof experiments,the masking of AM by FM andthe masking level.At higherfrequencies and levels a smallerchange is requiredat the of FM by AM was investigated.All modulationwas sinusoidal,and the outputof the integratorfor thresholdto be reached. cartierwas a I kHz tone.The maskingof 16-HzAM by FM as a function of themodulation frequency of theFM showedthe same broad tuning seen withAM modulationmasking [Bacon and Grantham, I. Acoust.Sec. Am. 85. 2575-25800989)]. This is consistentwith FM beingprimarily en- 10:15 codedas AM for small modulationdepths. Masking of 16-Hz FM by AM showedbroader tuning; this canbe attributedto the "secondcue" for FM 3aPP10. Gap detection thresholdsmeasured for synunetric and hypothesizedby Edwardsand Viemeister [J. Acoust.Sec. Am. 96, 733- asynunetrie marker frequency combinations surrounding a silent 740 (1994)]. AM detectionthresholds also were obtainedas a functionof temporal gap. Craig Formby (Dept. of Surgery,Univ. of Maryland the modulationindex,/3, of the FM masker.Thresholds approached 100% School of Medicine, 419 W. Redwood St., Baltimore, MD}, Sheldon modulationdepth for large/3, indicatingan inability to processenergy Lia• (JohnsHopkins Univ., Baltimore,MD 21218),and LaGuinn fluctuationsthat occurin both time and frequency.Finally, thresholdswere Sherlock (Univ. of MarylandSchool of Medicine,Baltimore, MD) obtainedas a functionof the relative phasebetween the maskerand signal modulations.These phase results are discussedwith respectto current Temporalgap detection (TGD) thresholdswere measured between si- modulationencoding theories. [Work supported by DC00683.] nusoldsthat varied in frequencyfrom 2000 to 3100 Hz for combinationsof 2, 3, or 4 markers(e.g., combinations of oneor two pre-gapmarkers with oneor twopost-gap markers). Sinusoidal frequencies F• andF 4 wereused 9:30 as pre-gapmarkers, while F 2 and F 3 servedas post-gapmarkers. TGD thresholdswere measuredfrom three normal-hearingadults who tracked 3aPP8. Detection of sinusoidal amplitude modulation having 70.7% correctdetection thresholds adaptively across blocks of 50 2AFC unexpectedrates. BeverlyA. Wright (Keck Ctr., Box 0732, Univ. of trials.For symmetricmarker conditions, where a pair or pairsof pre- and Calif., San Francisco,CA 94143-0732)and HuanpingDai (Univ. of Florida, Gainesville.FL 3261 I) post-gapmarkers are equivalentin frequencyon bothsides of the silent gap(e.g., F• = F2 or F• = F 2 andFa = F4),TGD thresholdsare small (i.e., The detectabilityof sinusoidalamplitude modulation having unex- < 10 ms). However,for asymmetricmarker conditions, where only three pectedrates was assessed using a probe-signalmethod. With thismethod, markersare presented ona trial(e.g., F•=F2, F•7:F3,no F4), perfOr- threelisteners were led to expecta targetmodulation rate (4, 32, or 256 manceis highly variable.TGD thresholdsfor asymmetricmarker condi- Hz) by presentingthe signalmost often at thatrate, and sensitivity to tionsmay be very large(e.g., 20-80 ms), and tendto increaseas the modulationat six otherunexpected rates between 4 and 256 Hz was mea- lrequency separauonis increasedbelween markers F 3 or F 4 and markers suredvia occasionallypresented probe modulation rates. The modulation F• = F 2. Thesepatterns of TGD resultsare inconsistentwith a masking phasewas random on each21FC trial andthe overall level of the 500-ms processand probably reflect mechanisms that are importantin groupingof widebandcartier was randomlyvaried between55 and 75 dB SPL across auditoryimages. [Research supported by NIH andThe Centerfor Lan- intervals.The modulationdepth at eachrate was set so that the modulation guageand Speech Processing, Johns Hopkins University.] alpresent ad- was detectedon about90% of the trials when only that rate was presented. dress: AT&T Bell Laboratories, 200 Laurel Ave., Middletown. NJ 07748. 3329 d. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of Amedca 3329 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 10:30 11:15 3aPPI1. The relafonship between auditory filter bandwidth and 3aPP14, Peak detectionfor auditory sound d'scrimination. JuliusL. temporalresolution. ElizabethA. Strickland (Dept.of Psych.,Univ. of Goldstein (CentralInst. for the Deaf, 818 S. Euclid,St. Louis,MO Florida,P.O. Box 112250,Gainesville, FL'32611-2250) 63110-1594)and JosephL. Hall (AT&T Bell Labs.,'Murray Hill, NJ Temporalresolutio• wasexamined inthe'context ofan envelope de- O7974-O636) tector model. This model incorporatestwo limits to temporalresolution: Auditorydetection of envelopemaxima in temporalresponses of co- filteringby theperipheral auditory system, and a centraltemporal window. chlearfrequeocy-analyzing filters has been hypothesi•d to accountfor It predictsthat temporal resolution should increase with the bandwidthof phaseeffects in psychophysicaldiscrimination [J. L. Goldstein,1. Acoust, the peripheralfilter up to a certainfilter width, beyond which it shouldbe Soc.Am. 41, 458-479 (1967)].Re-examination of this hypothesis in the determinedby the centrallimitations. To determinewhether the predicted contextof asymmetryof maskingJR. Hellman, Percept. Psychophys. 11, relationshipbetween peripheral filtering and temporal resolution could be 241-246 (1972)]reveals that it alsoprovides an adequateexplanation for observed,temporal resolution and auditory filter widthswere measured as this phenomenon.Peak discriminationbetween a tone and tone masker a functionof frequencyregion and level. Becauseauditory filters widen plusnarrow-band-noise probe is moresensitive to probeenergy than is the with level and with centerfrequency, the relatiohshipbetween temporal inversediscrimination between noise and noise masker plus to ne probe, in resolution and filter width could thus be tested both within and across agreementwith psychophysics.Simulations of this model indicatethat frequencyregions. Temporal modulation trax•sfer functions (TMTFs) were asymmetryof maskingis a functionof the productof noisebandwidth and measuredfor frequencyregions from 500 to 4000 Hz usingnarrow-band temporalduration. Psychophysical experiments on maskingasymmetry noise.Auditory filter functionswere measuredin the samefrequency re- were performedwith bothmasker and probe bandwidth ranging from pure gitns, usingthe notched-noisemethod with probelevel fixed.Both th• toneto supracriticalband. The experimentaldesign included both fixed and TMTFs and filter functionswere measured at two levelsin eachfrequency roving levels,with randomphases fixed throughouteach experiment. A region.As predic•l,time constants were correlated with filter width for standarddetection-theory model was fit to thedata, assuming that ratios of narrowfilters, and wereconstant for widerfilters. [Work partially sup- peaksor of normalizedpeaks are measured by anoptimal noisy discrimi- portedby a post-doctoralfellowship from NIH.] nator.Predictions based upon stimulusenvelopes are in goodagreement with the data. 10:45 11:30 3aPP12. The effect of lemporal placement on gap detectability. KarenB. Snell (Dept.of Audiol.,Rochester Inst. of Techno!.,52 Lomb 3aPP15.Auditory detectionof changesin massdensity and elasticity Memorial Dr., Rochester,NY 14623-5604) and Hue-Lu Hu (Smith of a tuning fork. RobertA. Lutfi andEunmi Oh (Dept.of Cornmum College,Nerxhampton, MA 01060) Disord.and Psych.,Univ. of Wisconsin,Madison, WI 53706) The detectabilityof a maskedsinusoid increases as its onset ap- The principlesof theoreticalacoustics were applied to reconstructthe proachesthe temporal center of a masker.This study was designed to sound-pressurewaveform atthe ear as would be generated byan idealized detemlinewhether a similarchange in detectabilitywould occur for a tuningfork (struck,clamped bar). The resultis an inharmonicsum of silentgap as its onsetwas parametricallydisplaced from the onsetof a dampedsinusoids whose individual acoustic parameters (frequency, inten- noiseburst. Gap thresholdswere obtainedfor four subjects.Signals were sity,and decay modulus) are determined by themass density and elasticity 150-ms,6-kHz low-passednoise bursts presented at an overalllevel of 75 of the materialcomprising the bar.In the standard2IFC procedure,listen- dB SPL. A 10-mscosine-squared envelope shaped the onsetand offset of erswere asked, in effect,to detectchanges in the materialcomposition of the noise burst. Gaps were shapedby a 1-ms cosine-squaredenvelope. the bar basedon their perceptionof the acousticwaveform. Listener strat- Gapsonsets were displaced by 0, 1, 3, 5, 10, 30, 50, 100, 110, and 120 ms. egiesfor detectingsuch changes were estimated by perturbingslightly the The displacementwas measuredfrom the first point of full amplitude individualacoustic parameters from trial to trial andcomputing correla- following the 10-ms shapedonget. Gap thresholdswere determinedin a tionswith the listener's response [cf. R. A. Lutfi andE. Oh, J. Acoust.Soc. 3IFC procedureusing 75-trial runs. Subjectscompleted five replications Am. 95, 2963(A) (1994)].In general,the correlationsrevealed that listen- withoutprior practice.The mean gap thresholdwas largestfor the noise ersfail to makeoptimal use of theinformation in theacoustic waveform by burstclosest to signalonset (5.67 ms) and smallest for thegap offset by 60 tendingto giveundue weight• for a givenmaterial change, on one or more ms from the signalonset (2.01 ms).For all subjects,gap thresholds de- parametersof the acoustic waveform. The results are discussed in terms of creasedas the gap approachedthe noiseburst center. their implicationsfor ecologicalnotions regarding the perceptionof "higher-order"variables in the determinationof naturalresonant sources. [Researchsupported by NIDCD.] 11:00 3aPP13. Shared attention in detection and identification. Ervin R. 11:45 Halter and Anne-MadeBonnel (Dept. of Psych.,Univ. of California, Berkeley,CA 94720} 3aPPI6. Estimatingperceptual distributions for endpointstimuli. M. E. H. Scboutenand A. ]. vanHessen (Res. Inst. for Lang. and Speech, Brief,incremental iS(+)] or decrementaliS(-)] signalswere added to UtrechtUniv., Trans 10, 3512 JK Utrecht,The Netherlands) an ongoingpedestal. For detection,correct responses were either "yes" to bothS(+) andS(-) or "no"to nonsignaltrials. For identification, a signal Ratherthah to assume that all stimuli on a continuumgiverise to waa prc.a•nt•l on •¾orytrial and rc•ponscawere either "$(*)" or "$(--)." perceptualdismbuUons that are Gaussianand equal,it is sometimesde- Subjectsmonitored either a single channelor, in the "dual task," two sirableto determinethese distributions more directly, for examplewhen simultaneouschannels with independentstimuli. Expanding on previous thestimuli are speech sounds'. This can be done by meansof (absolute) work with two visual stimuli, here there were one visual stimulus(on a identificationor (non-numerical)magnitude estimation. A problemwith CRT) and one auditory(pure tone). As before,dual-task performance in suchmethods is thatthe apparentdistributions obtained with thembecome detection was better than in identification. In addition, detection was as skewedas thestimuli approach either end of thecontinuum. An attempt goodon eachof two channelsas on one alone,indicating parallel 9rocess- was made to-recoverthe underlyingdistributions by extendingthe re- ing, but identificationdeclined, suggesting shared attention. Testing the sponserange by threestimulus steps beyond the continuumendpoints, ideathat pedestal-to-signal transients account for thesedifferences, pedes- bothfor intensityand for stopconsonants. The resultingdistributions were tals wereturned off beforeand after the signalintervals, removing tran- fitted by meansof Gaussianfunctions, so that a direct measureof d' in sientsas sourcesof information.This did not affect identification,but thesetasks was obtained. It is assumedthat in tasks'Utherthan identifica- detectionwas now worsethan identificationand declinedin the dual task, tionor magnitudeestimation, the widths of thedistributions change, but suggestiveof sharedattention. that their means are unaffected. 3330 J. Acoust.Soc. Am., Vol. 97, No.5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3330 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp THURSDAY MORNING, 1 JUNE 1995 MEETING ROOMS 12, 13, 14, 8:30 TO 11:35 A.M. Session 3aSA Structural Acousticsand Vibration: Structural Intensity I SabihI. Hayek, Cochair Departmentof ErtgineeringScience and Mechanics,Pennsylvania State University,University Park, Pennsylvania16802 Scott D. Sommerfeldt, Cochair GraduateProgram in Acoustics,Pennsylvania State University,University Park, Pennsylvania16802 Chair's Introduction•8:•O Invited Papers 8:35 3aSA1.The equation of diffusionapplied to energydensity of vibratingbeams. Myriam Djimadonm (L.V.A., I.N.S.A. B•t 303, Viileurbanne,France) and JeanLouis Guyader (InstitutNational des Sciences Appliqu6es, 69621 Villeurbanne Cedex, France) Inspiredby precedentstudies on thepossibility of writingsimple differential equations governing the evolution of vibratoryenergy density[D. J. Nefskeand S. H. Sung,Trans. ASME Ill, 94-100 (1989)],and equation of diffusionand its relatedconditions at discontinuitieshave been developed for an energetic quantity • in thecase of flexuralwaves propagating in beams, where • represents the space-averagedfar-field part of the displacementautospectrum, is proportional to energydensity, but doesnot needextra time averaging.Several assumptions based on frequencyand spaceaveraging allow writingenergetic conditions at discontinuitiesand defininga completeformalism for monodimensionalproblems. The procedureis appliedto twocoupled Euler Bernoulli beams: • is numericallyin very goodagreement with "exact" spaceand frequency-averagedfar-field results and so the conditionsat disconti- nuitiesare validated. Knowing that • allowsfor the abilityto obtainan approximationof theenergy flow in thehearns and so gives an ideaof how theenergy propagates in the structure.These good results are encouraging, but the generalizationof theprocedure to platesis not trivial and requiresfurther assumptions. 3aSA2. Measurement of the flexural wave power transm'ssion and reflection coefficients of joints using wave-number domainmethods. RobertJ. Unglenieksand Robert J. Bernhard(School of Mech.Eng., Purdue Univ., 1077Ray W. HerrickLab., WestLafayette, IN 47907-1077} Recently,a numberof investigatorshave proposedso-called energy flow analysistechniques to allow engineersto perform high-frequencystructural vibration studies of coupledstructural elements. One key parameterrequired for this analysisis the power transmissionand reflectioncoefficients of the joints that couple structuralelements. A wave-numberdomain technique has been developedwhich uses a spatialfast Fourier transform to transformvelocity data obtained in the spatial/frequencydomain into the wave-number/frequencydomain. The resultingwave-number domain spectrum allows estimation of energyflow segregated into right andleft travelingcomponents. Using the segregated energy flows for all of the structuralelements coupled at a joint, it is possibleto estimatethe power transmission and reflection coefficients of thejoint. A ladderframe structural system is analyzedto determinethe flexuralwave power transmission and reflection coefficients of ell- andtee-joints that comprise the structure. The structureis forced so thatonly flexural and longitudinal waves are excited. A scanninglaser Doppler vibrometer is usedto collectthe flexuralwave velocitydata. The estimatesof thejoint coefficientsare presentedand compared to the analyticalvalues for rigidjoints. 9:25 3uSA3.Active controlof structuralintensity in an elasticplate. S.I. Hayek,M.-Y. Nam (Dept.of Eng. Sci. and Mech., Penn StateUniv., University Park, PA 16801),and S. Sommerfeldt(Penn Slate Univ, University Park, PA 16801} Active controlof structuralintensity (SI) in a finite elasticplate coupled to a point damperis achievedthrough the useof a judiciouslylocated actuator. An algorithmwas developed using the magnitudeof the structuralintensity vector to achievelocal or globalreduction of SI. Thecontrol algorithm showed that controlling each component of the intensity vector (I• or ly) generatesa parabolicsurface, which may or maynot intersect the null plane. Under certain conditions based on thelocations of theprimary mechanicalsource and the errorsensors, as well as the dynamicparameters of the plate,the surfaceintersects the null plane.If the surfaceintersects with the null plane,then the intersectiongenerates a circle of possibleactuator magnitudes and pt•asesthat will make either!•=0 or !y=0. If thecircles exist for both i,=0 andIF=0, theninequalities were derived that will indicatewhen and if these circleswill intersect.The intersectionof thesecircles allows only two possiblecontrol solutions that will makethe magnitudeof the vector SI at the error sensor vanish. When the intersections do not occur, then minimization rather than extinction is achieved. These controlstrategies are explored and applied to an elasticsimply supported plate coupled to a pointdamper and excited to vibrationby a pointforce. The roleof structuraldamping on controlstrategies is fully explored. 3331 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3331 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 9:50 3aSA4. Structural and acousticintensity analysisfor a fluid-loadedelastic plate with a distributed inhomogeneity. J.M. Cusehieri(Ctr. for Acoust. and Vib., Dept.of OceanEng.. Florida Atlantic Univ., Boca Raton, FL 33431)and D. Felt (DavidTaylor Res. Ctr., Bethesda,MD 20084) The solutionsdeveloped for theresponse and scattered pressure from a fluid-loadedplate with a distributedmass inhomogeneity, whichwere presented at theASA 128thmeeting in Austin,Texas, are extendedto includeddistributed stiffness inhomogeneities. The samefour typesof distributions,with varyingdegrees of "smoothness"are consideredfor the stiffnessdistribution. The scattering characteristicsbetween the massand stiffnessinhomogeneities are different,and while the scatteringis dipolelikefor the mass inhomogeneity,it is quadrupolelikefor the stiffnessinhomogeneity. The resultsfor this presentationare presentedin the form of structuraland acoustic intensity maps, both as vectorplots and streamline plots. For frequencieslower than the criticalfrequency of the fluid-loadedplate, the resultsshow the constantexchange of powerbetween the plate and the fluid. The streamlineplots for the reactiveintensity show a bandvery closeto the plate surface.For higherfrequencies, the characteristicsof the intensitymaps become dependenton the relative length and "smoothness"of the distributedinhomogeneity. 10:15 3aSAS.Vortidty characteristicsof the vibrationintensity field and the structure-bornesound. NobuoTanaka (Vib. andSound Div., Mech.Eng. Lab., 1-2 Namiki,Tsukuba Science City, Ibaraka305, Japan) This paperdeals with the characteristicsof real vibrationalpower flow in a simplysupported rectangular panel under the action of feedforwardvibration control. It is foundthat the pathof the powerflow is a combinationof translationsand rotations, the rotations inducedby the interferenceof two modeswhich products a "vortexgenerating block." Particular emphasis is placedon the vortex powerflow in the vibrationintensity field. A qualitativeformula for predictingthe numberof power flow vortices,as well as the discussionof thevortex period, is putforward. Then, by introducingan energy stream function, the generation mechanism of thevortex powerflow is quantitativelydiscussed. The fundamentalcharacteristics of thevortex power flow are further clarified by vortexfunction derivedfrom the intensityfield. A novel methodto inducea vortexat an arbitrarylocation of the plateis alsoshown, which may have practicalapplications in controllingthe path of vibrationalpower flow in systemsof large extent.Moreover, the influenceof the inducedvortex power flow on theplate onto the acousticintensity distribution is investigated,showing that the rotationaldirection of the vortexon the plateis not alwaysthe samewith thatof the acousticintensity in the nearfield. 10:40-10:50 Break ContributedPapers 10:50 structure.The power flow analysisfor differentjoint parameterswas per- formed.The relationshipbetween the joint parametersand the powerflow 3aSA6. Vibration studiesof joints in structures. S. K. Kim and M. wasinvestigated. The powerflow measurementsystem was calibrated in a G. Prasad (Noiseand Vib. ControlLab., Dept. of Mech. Eng.,Stevens Inst. of Technol.,Castle Point on the Hudson,Hoboken, NJ 07030) steppedbeam with knownreflection coefficient of the step,and then the measurementswere carriedout on aluminumbeams with epoxybonded Jointsare usedextensively in connectedstructures which are part of joints.The measuredresults agreed well with the theoreticalprediction. machinesystems. Joints introduce discontinuity in structureswhich not The terminationeffects on the powerflow measurementare discussed. only disturbthe energy flow butare also possible locations of failure.Thus it is necessaryto characterizethe joints to determinetheir rigidity. A joint can be characterizedin termsof the energyreflection coefficient and iru- pedance.This study presentsboth analyticaland experimentalwork on vibrationcharacterization of joints.The analyticalwork is basedon both 11:20 classicaland finite-elementmethods. The experimentalwork is basedon the two sensormethod for impedancemeasurements. The vibrationbehav- 3aSAS. Structural intensity of acoustically excited waves in a ior of a joint is studiedin termsof reflectioncoefficient and impedance. flu'd-loaded elastic plate. StevenL. Means and Ralph R. Goodman The joints consideredare bolted joints in specimenstructures such as (Appl.Res. Lab., P.O. Box 30, PennState Univ., State College, PA 16804) cantileverbeams. Good results are obtained which supports the application of suchstudies in designand diagnostics of stmctaraljoints. [Work sup- When an acousticplane wave is incidenton a elasticplate, various portedby DaewooMotor Company, Seoul, Korea.] wave typesare excitedin the platefor differentangles of incidence.The presentstudy determines the structuralintensity as a functionof incident 11:05 angleat differentdepths along the crosssection. It is foundthat for near normalineidenea the diraetionof the intensityparallel to th• planoof tho 3a$A?.Vibrational power flow throughadhesively bonded beams. plateis oppositethe intensityin the fluid andfor otherangles of incidence. QunliWu, Yiren Hong,and M. K. Lina (Schoolof Mech.and Prod. Eng., Previously,a similaranalysis for a semi-infinitemedium by Bunneyand NanyangTechnoL Univ., Singapore2263, Republicof Singapore) Goodman[J. Aeonst. Soc. Am. 53, 1658-1662(1973)] did not yield such A theoreticaland experimental study of powerflow throughadhesive a result.To gainphysical insight into this phenomenon,a study was per- lap-jointbeams was carried out in thispaper. The mathematicalmodel of formedto determinewhich wave modesare excitedat theseangles of powerflow in thebeams was developed by treatingthe joint asa sandwich incidenceand to calculatetheir group velocities. 3332 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3332 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp THURSDAY MORNING, 1 JUNE 1995 AUDITORIUM, 8:20 A.M. TO 12:00 NOON Session 3aSC SpeechCommunication: Contacting Linguistic Structure from Perception JohnC. Kingston,Chair Universityof Massachusetts,Box 37130, Amherst,Massachusetts 01003-7130 Chair's lntroduction•8:20 Invited Papers 8:25 3asCl. Accessto phonologicalstructure in listeningto speech, CarolA. Fowler (HaskinsLabs., 270 CrownSt., New Haven,CT 06511) in a direct-realisttheory of speechperception, listeners are in immediate(in thesense of unmediated)contact with the phonological unitsof theirlanguage when they use structure in acousticspeech signals as information for itscausal source--phonological gestures of the vocaltract. In the theory,phonological categories include, minimally, the setsof motor-equivalentartieulatory movements producibleby a synergyof the vocal-tract,each set, thereby, counting as a tokenof the samephonological gesture for producer/ perceiversof speech.Maximally, categories include a setof similargestures that members of a languagecommunity do notdistinguish. Categories,thus, are definedgesturally, not acoustically,as for example,research on prototypesin speechhave been interpreted as suggesting.Striking behaviors of listenersthat index their extraction of informationabout phonetic gestures from the acoustic speech signalis theirparsing of acousticsignals. A literaturereview suggests that listeners do nothear such unita• acousticdimensions as fundamentalfrequency or durationas unitary. Rather, they parse each dimension into its distinct, converging gestural cause. Comple- mentarily,listeners use as information for a phonologicalunit the constellation of diverseacoustic consequences of the units gestural realization.[Work supported by NICHD.] 8:50-9:05 Commentary by Patricia K. Kuhl Departmentof Speechand Hearing Science,University of Washington,WJ-10, Seattle, Washington 98195 9:05•9:15 Discussion 9:15 3aSC2.Undoing place assimilation. Aditi Lahiri (FachgruppeSprachwissenschaft, Post Fach 5560, Univ. Konstanz,D-7750 Konstanz,Germany) Phonologicalvariation in the form of differentphonetic shapes of wordspose a challengefor theoriesof speechperception and languagecomprehension. Postlexical phonological processes like assimilationand deletionfrequently cause the phoneticshape of a wordto changein a givenphonological context. Such processes can easily lead to the creationof nonwords.In a sentencelike "I detest greenbananas," the word green may well be pronouncedas [grim]in thecontext of a following[b]. Listeners,however, apparently haveno problemsin parsingand identifyingthe wordcorrectly in ongoingspeech. How is the linguisticsystem organized such that it canaccept the sequence[grim] as the wordgreen? In thistalk, compefng theoretical accounts dealing with suchvariation will be presented.An accountwhich assumes a highlyabstract lexical representation will be presented.This accountassumes that the central componentof the linguisticsystem is the lexiconwhich contains,among other things,a dictionaryof uninflectedwords with their phonologicalforms. semantic properties, and syntactic properties of varioussorts. The phonologicalform is assumedto havea highly abstractrepresentation on thebasis of whichthe listeneraccepts or rejectsphonetic variance. In addition,a recenthypothesis will be arguedagainst that assumes an on-lineprocess of phonologicalinference and an abstractrepresentation will be presentedto dealwith phoneticvariation. The data to supportthe hypothesiscomes from Germanassimilation processes. 9:40-9:55 Commentary by Paul A. Luce PsychologyDepartment, State Universityof New York,Buffalo, New York 14260 9:55-10:05 Discussion 10:05-10:20 Break 10:20 3a$C3. On the internall•ercel•tual slructure of phonolo•icalfeatures: The [voice]distinction, RandyL. Diehi, WendyA. Castleman(Dept. of Psych.,Univ. of Texas,Austin, TX 78712),and JohnKingston (Univ. of Massachusetts,Amherst, MA 01003) Apartfrom phonological features and their individual phonetic correlates. an intermediatelevel of structureapparently exists in whichsubsets of phoneticproperties form perceptuallycoherent units, referred to hereas "integratedperceptual properties." The mappingbetween each successive level of structureis arguablymany-to-one, elevating both redundancy and distinetiveness at the level of phonologicalfeatures. For the distinctive feature [voice], a mainintegrated perceptual property corresponding tothe [+voice] value 3333 J. Acoust.$oc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3333 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp is the presenceof low-frequencyenergy during or nearthe consonant, which may be furtheranalyzed into at leastthree phonetically distinctsubproperties: voicing during the consonant constriction, a low FI nearthe constriction, and a low F0 in the sameregion. Two predictionsfollow if thesethree subproperties contribute to a singleintegrated perceptual proper•y. One is thatthe effects on [voice] judgmentsof varyingeither a low FI or F0 shouldpattern in similarways for a givenutterance position and stresspattern; this predictionwas confirmed. The secondprediction is thattwo stimuliin whichseparate subproperties of the low-frequencyproperty are positivelycorrelated (i.e., they are eitherboth present or bothabsent) will be moredistinguishable than two stimuliin whichthe subpropertiesare negativelycorrelated; though not yet confirmedfor the pairingof Fl with F0, this predictionwas confirmedfor pairingsof F 1 or F0 with constrictionvoicing. 10:45-11:00 Commentaryby Burr Schouten ResearchInstitute of Languageand SpeechTransmission, University of Utrecht,103512 JK, Utrecht,The Netherlands 11:00-11:10 Discussion 11:10 3aSCA.Speech perception as a patternrecognition. Terranee M. Nearey (Dept.of Linguist.,Univ. of Alberta,Edmonton, AB T6G 2E7, Canada) Phoneticsinvolves three domains of events:(1) acoustic/auditory,(2) articulatory/gestural, and(3) symbolic/phonological.Theo- riesof perceptionhold different views about the relationships among these domains. Auditorists (e.g., Kingston and DieM) emphasize a strong(i.e., simple, direct) relation between (1) and(3). Gesturalists(e.g., Liberman and Mattingly) propose a strong relation between (2) and (3). Advocatesof double-strongtheory (e.g., Blumstein and Stevens)propose strong relations of both (1) and (2) to (3). Difficultieswith all thesetheories will be discussed.An alternative,"double-weak" theory will be describedand evidence supporting it will be presented.This approachviews speech production and perception as distinctbut cooperative systems. This view acceptsthe gesmralistcontention that the acousticmapping if phonologiealuni• is modifiedby contextin waysthat are importantto perception. However,it also contendsthat the accommodationof contextualeffects in perceptionis limited and highly stylized.Assuming a concomitantstylizatiou of gesturalpatterns in production,relatively simple pattern-recognition strategies in perceptionmay suffice for successful communication. 11:35-11:50 Commentaryby Keith R. Kluender PsychologyDepartment, University of Wrtsconsin,Madison, Wisconsin 53706 11:50-12:00 Discussion THURSDAY MORNING, 1 JUNE 1995 GRAND BALLROOM SOUTH, 7:45 A.M. TO 12:00 NOON Session 3aUW Underwater Acousticsand Acoustical Oceanography: SeismoacousticDetermination of Sea Ice Processes Peter J. Stein, Chair ScientificSolutions, Inc., 18 ClintonDrive, Hollis, New Hampshire03049-6576 Chair's Introduction--7:45 Invited Pap•r• 7:50 3aUWI. Determinationof seaice processes using geophone arrays. PeterJ. Steinand Steven E. Euerle (ScientificSolutions, Inc., 18 Clinton Dr., Hollis, NH 03049-6576) Similarto land-based geophysics, seismoacousfic techniques arenecessary tostudy sea ice mechanics. Most ice fracturing can only be detectedvia theelastic/acoustic waves which radiate. One of thebest means of determiningthe spatially averaged mechanical propertiesis through probing the ice with elastic waves. Here the results are described from two separate experiments in which large (orderl-kin aperture) arrays of triaxialgeopbones were deployed tostudy the sea ice mechanical properties via the elastic waves which propagatein the ice. The first test was conducted on"clean" first-year shore-fast ice off the coast of ResoluteBay Canada in Spring 1992.The second was a winter-oversystem deployed on multiyear ice during the Fall 1993SIMI fieldoperation in theBeaufort Sea 3334 J. Acoust.Soc. Am., Vol. 97, No.5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3334 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp (subsequentlyrecovered in March1994). Additionally, during SIMI an automated"hammer blow" source was deployed which impactedthe ice every 7 h. Varioussignal processing and data analysis techniques forstudying sea ice processes such as ice growth andthermal fracturing will be described. Results will be presented along with comparisons between first-year and multiyear ice. [Work supportedby ONR.] 8:10 3aUW2. Seismoacousticobservations as relatedto thermallyinduced stresses and fracturing in pack ice. JamesK. Lewis (OceanPhys. Res. & Dev.,207 S. SeashoreAve., Long Beach, MS 39560) On-icegeophone data and under-ice noise data contain a significantamount of informationabout the stress state of packice and howice fractures in responseto thestress. This information can be usedto studythe theology of seaice and the related mechanics of fracturing.A review is presented of thecurrent understanding of ice mechanics related to thermal fracturing based On seismoacoustic observations.A theology is presentedand discussed based on a thermodynamicmodel and an associated stress/strain relationship. The rheologyhas an enhancement which prescribes how the extent of existingcracks in the ice affect (1) thestress state of theice, (2) the numberof fractureswhen the ice exceeds its yieldstrength, and (3) thestress relief after fracturing occurs. This ,allows us to simulate first-yearand multiyear ice using the same model by differentiating the two ice types based on the extent of existingcracks. Examples are shownof how under-iceacoustic data can be usedto estimatethe verticaldistribution of the fractionalarea of existingcracks in multiyearice. 8:30 3aUW3.Seismo-aconstic remote sensing and inversion of seaice fracture events. H. Schmidt,Y. Dudko (MIT, Cambridge,MA 02139), K. yonder Heydt, and E. K. Scheer(Woods Hole Oceanogr. Inst., Woods Hole, MA 02543) A new,layered seismo-acoustic remote sensing concept was developed and applied during the SIMI fieldexperiments in the BeaufortSea in theFall of 1993and the Spring of 1994.A large-aperture,32-element, horizontal hydrophone array was used to record theacoustic emission from ice events.Using real-time array processing, maps of the seismicactivity of theice coverout to a range of 2 to3 kmwere continuously generated. Once an active zone was detected, clusters of five3-axis geophones and a singlehydrophone weredeployed in theactive zone for near-fieldrecording of theseismo-acoustic emission. The data were transmitted back to themain campvia a wirelesslocal area network, and recorded on tape.During the Spring experiment data were recorded continuously on the hydrophonearray for 4 weeks,and several deployments of the geophoneclusters were performed in the vicinityof activeice mechanicalprocesses such as ridge building, finger rafting, and floe fracturing. In addition,the clusters were deployed on specimens usedfor artificialfracturing experiments. The layeredremote sensing concept is described,and examples are given of the seismo- acousticemission produced by thedifferent types of iceevents. Finally, the matched-field fracture plane analysis of theseismic data is described. 8:50 3aUW4.Acoustic and seismic measurement of ice processes.David M. Farmerand Yunbo Xie (Inst.of OceanSci., PO. Box 6000,'Sidney,BC V8L 4B2,Canada) ' Assea ice responds toenvironmental forcing, it deformsleading to thestorage of strainenergy. When mechanical failure occurs, mostofft,his energy isdissipated through fracturing, buta smallportion radiates asseismic and acoustic waves. These waves provide usefulsignals ,forsensing thefailure process inthe ice. In a recent ice mechanics experiment conducted northof Prudhoe Bay(SIMI '94), a largenumber of icefailure events were observed using geophone and hydrophone arrays. Preliminary results are presented, includinga large-scale tensile fracture test and naturally occurring sounds near a closinglead. For the artificial fracture, the acoustic signalsallow determination of cracking rate, fracture advance, and crack propagation velocities. The overall crack propagation speed is estimatedto beof order50 m s 4;maximum cracking activities occur prior to peakloading. In thesecond data set, the naturally occurringstick-slip process was observed astwo ice sheets moved agalnst'l•ach other in a closinglead. A widerange of frequencies canoccur simultaneously representing different components of thesliding and slipping mechanisms. 9:10 3aUW5.A studyof the evolutionof under-icefresh water layer during summer melt phase in theArctic. SubramaniamD. Rajah,Henry Laible (Woods Hole Oceanogr. Inst., Woods Hole, MA), and WaiterB. Tucker,III (ColdRegions Res. and Eng. Lab., Hanover,NH) In theArctic, the entire snow cover and a significantpart of theice melt during the summer months. The melt water, which is at about0 øC,reaches the underside of theice whereit overliesmuch colder and denser saline water and forms under-ice melt ponds. It hasbeen suggested that these under-ice melt ponds can play a significantrole in heatflux through the ice. The changes in acoustic propagationina region very close to the bottom of the ice using data collected during amultiseason cross-hole tomography experiment conductedinthe Arctic are presented. Since acoustic propagation isdependent onthe properties of the medium, the changes inacoustic propagationto the changes in the characteristics of the medium are related. Further an investigation is made as to whetherthese changescorrespond tothose observed byMartin and Kauffman [J.Fluid Mech. (1974)] in a laboratoryexperiment conducted tostudy thedevelopment of under-ice melt ponds. [Work supported byONR.] 9:30 3aUW6.Seismoacousfic ultrasonic modeling characterization of seaice processes.Jacques R. Chamuel(Sonoquest Adv. Ultrason.Res., P.O. Box 81153,Wellesley Hills, MA 02181-0001) Seaice processes affect the elastic properties, structure, and boundaries of the ice cover, and change the composition and acoustic propertiesof the top water layer underneath theice. Upward refraction in the water creates substantial interaction between underwater acousticwaves and the ice cover influencing long-range low-frequency propagation. In order to developa basicunderstanding of sea 3335 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3335 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp ice processes,it is essentialto characterizeseismoacoustic phenomena associated with seaice growth,melting, refreezing, cracking, ridging,and rafting.Controlled laboratory experiments were conductedto studydiverse transient liquid/solid seismoaeousti½ wave phenomena.Examples from scaledultrasonic modeling results are presentedcharacterizing near-grazing Scholte wave backscattering from trenchesat liquid/solidinterfaces, effective attenuation of flexuralwaves from horizontalrefraction, seismic profiling from 45ø obliqueboreholes, viscous waves in ice suspensions,variability of shearwave speedin seaice cores,edge wave propagationalong truncatedand range-dependentapex angle wedges,focused multiple scattering, and finger-rafting.The findingsprovide physical insightinto high-latitude seismoacoustic oceanography and contribute to theinterpretation of Arctic field data. [Work supported by 9:50-10:00 Break Contributed Papers 10:00 nitelylong cylinder. The solutionis extendedfor Iow-ka wavepropagation in orderto determineeffective toodull (Lam6 parameters and density) and 3aUW7. Ice activitiesduring the AREA 88 experiment.I. A pictorial effectivewave speeds.An experimentis conductedin the lab to determine and videodescription. T.C. Yang (NavalRes. Lab., Washington, DC the scatteringcross section versus angle for a singlecylindrical scatterer 20375) for frequenciesof 160 and 200 kHz. In addition,effective moduli are Duringthe AREA 88 experiment(Spring of 1988),an ice campwas determinedas a functionof cavity concentration.The experimentaland deployedon an ice floe in the generalneighborhood of 78 N and55 W in theoreticalresults are presented. [Work supported by ONR.] the centralArctic. The ice floe becameactive on and off for a periodof days.The ice activitieswere clearlyaudible in the air (a kind of low- 10:45 frequencyroar). One can unmistakably determine the direction of thenoise by steppingoutside the tent. Openand refrozenleads were foundbetween 3aUW10. Temporal evolution of compressionalwave speed in sea the floes.One of themquickly closed up in a matterof minutesswallowing ice. SubramaniamD. Rajan (WoodsHole Oceanogr.Inst., Woods Hole, up the geophonesjust deployedon the refrozenlead. Immediately follow- M•A02543) ing this leadclosing, the floe next to us startedto movelaterally at a speed approximately3 fffmin. During a peak ice activityperiod, the ice at the A year-longcross-hole tomography experiment was conductedin sea edgeof our ice floe startedto pile up into a form calledice ridges,appar- ice during 1992 to 1993. The analysisof the data is presorttedand the entlydue to forcesbetween the ice floeswhich broke the ice and pushed variationsin thecompressional wave speed structure in seaice with season them into a pile of irregularshapes. This ice ridgingwas recordedon a are investigatedand relatedto the changesthat are predictedby thermo- videotape. Tens to hundredsof blocksof ice of about5- to 10-ftthickness dynamicmodel. [Work supported by ONR.] were also found neatly lying on top of adjacentice floes,a scenewhich looked tike an act of God. 11:00 3aUWll. A mode of nonlinear behavior of ice cracks. Lev A. 10:15 Ostrovsky(NOAA/ERL/EWIJCIRES, 325 Broadway,R/E/ET-1, Boulder, 3alJW8. Ice activities during the AREA 88 experiment. I!. Noise CO 80303), AlexanderE. Ekimov,Andrey V. Lebedev,and Alexander events recorded on geophones. T. C. Yang (Naval Res. Lab., M. Sutin (inst.of Appl. Phys.of RussianAcad. Sci., Nizhni Novgorod Washington,DC 20375) 603600,Russia) Duringthe AREA 88 experiment(Spring of 1988),an ice campwas A work presentedat the previousASA meetinghas demonstrated that deployedon an ice floe in the generalneighborhood of 78 N and 55 W in the cracksmay provideanomalously strong vibroaeousfic nonlinearity in the centralArctic. The ice floe becameactive on and off for a periodof ice. Experimentaldata were obtainedfrom the field experimentson a days.Many of the noiseevents were recordedon a planararmy of geo- •esh-waterlake, where a strongsubharmonic signal was, in particular, phones.The responseof three-axisgeophones were used to analyzethe registered.Here, a theoreticalmodel is suggestedfor the descriptionof the forcingmechanism of the noiseevents by comparingthe geophooere- effectsobserved and possibleuse of them for characterizingthe crack sponseto the ice activitieswith thatgenerated by man,i.e., hammerblows. parameters.The model is basedon considerationof nonlinearflexural Specifically,frequency-wave-number analysis was used to sort out the oscillationsof the ice platewith a crackwhich may be "opened"from its longitudinal,shear, and flexural waves in the geophonedata. While the upperor lower part due to flexural oscillations.Together with the added examplesshown here indicatethat floe bumping/rubbingwas the likely massof the surroundingarea of the plate,a nonlinearoscillator may be causefor the very-low-frequencynoise signals analyzed, long-term accu- formedwhich admits both higher harmonic and subharmonic generation (a mulativegeophone data indicatevertical forcing was the dominantsource parametriceffect). The oscillator has a strongnonlinearity and relatively for ice generatednoise. low Q factorwhich may providea possibilityof paramea'icexcitation if thereis a ratherwide frequencyrange. The modelconsidered seems to be applicablefor real seaconditions. 10:30 3aUW9. Acoustic scattering in an elastic medium as it relates to sea 11:15 ice and the determination of effective toodull. Henry A. Laible (Woods Hole Ooeanogr.Inst. and MIT, Woods Hole, MA 02543) and 3aUWI2. Acoustic measurements of ice cover variations in the SubmmaniamD. Rajan (WoodsHole Oceanogr.Inst., WoodsHole, MA Arctic Ocean. Victor V. Artel'nyi and Mikhail A. Raevsky (Inst. of 02543) Appl. Phys.,46, UlyanovSt., 603600Nizhny Novgorod,Russia) The scatteringof soundin ice is a complexproblem which depends Climaticmonitoring of the ArcticOcean implies long-duration obser- upon the materialproperties of the ice as well as the frequencyof the vationsof theice cover and water temperature variations by measuringthe soundsource. Because of the complexityof the problem,a simplified characteristicsof low-frequencyacoustical signals traveled along station- approachto acousticwave scatteringis taken. The ice is modeledas a arypaths. The sensitivityof soundingsignal parameters to thevariations of two-phasemedium in which fluid-filledcylindrical cavities (brine chan- the ice covercharacteristics is one of the importantproblems in climatic nels)are embedded in an attenuatingelastic matrix. An analyticalsolution monitoring.The timestructure of thepulse signal in theArcfie waveguide is obtainedfor the acousticscattering of longitudinalwaves from an infi- is investigated.The relativeinfluence of the ice coverthickness, density, 3336 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of Amedca 3336 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp shear,and compressional sound speeds on the variationsof the phaseand the ice coverdrift are consideredas signalfluctuations sources. According time delayof the normalmodes is studied,It is foundthat, in the frequency to the data of numerical simulation, the influence of submesoscaleeddies rangef•<30 Hz, the variationsof the ice coverdensity and thicknessare is primary. more efficient than sound-speedvariations. Taking the desalinationof the subsurfacelayer into accountdecreases ice thicknessinfluence. These ef- 11:30-12:00 fectsare comparedwith signalfluctuations in the Arctic Ocean.The fluc- tuationsof the cw signalof the frequencyf=20 Hz in the Arctic wave- guide are investigated.The internal waves, the submesoscaleeddies, and PANEL DISCUSSION THURSDAY MORNING, 1 JUNE 1995 MEETING ROOM 17, ROOM, 9:00 A.M. Meeting of AccreditedStandards Committee S2 on MechanicalVibration and Shock to be held jointly with the U.S. TechnicalAdvisory Group (TAG) Meeting for ISO/TC 108 MechanicalVibration and Shock D. J. Evans, Chair S2 National Instituteof Standardsand Technology(NIST), Building 233, RoomA 147, Gaithersburg,Maryland 20899 D. E Muster,Chair, U.S. TechnicalAdvisory Group (TAG) for ISO/TC 108, MechanicalVibration and Shock 4615 O'Meara Drive, Houston, Texas 77035 StandardsCommittee S2 on Mechanical Vibration and Shock.Working group chairs will presentreports of their recentprogress on writingand processingvarious shock and vibrationstandards. Them will be a reporton the interfaceof S2 activitieswith thoseof ISO/TC 108(the Technical Advisory Group for ISO/TC 108consists of membersof S2, S3, andother persons not necessarily members of thosecommittees) including a reporton the activitiesof ISOFFC108, includingplans for its September1996 meeting in Sydney, Australia. Scopeof S2: Standards,specifications, methods of measurementand test, and terminology in the fieldsof mechanicalvibration and shock,and condition monitoring and diagnostics of machines,but excluding those aspects which pertain to biologicalsafety, tolerance, and comfort. THURSDAY AFFERNOON, 1 JUNE 1995 MEETING ROOM 16, 12:45 TO 2:20 P.M. Session3pAA Architectural Acoustics: Room Acoustics--Measurements AngeloJ. Campanella,Chair CampanellaAssociates, 3201 RidgewoodDrive, Columbus,Ohio 43026 Chair's Introduction--12:45 ContributedPapers 12:50 2900 real time analyzerand soundlevel meterwas usedto recorda rapid sequenceof octaveband spectra from impulsive sound. A PC programwas 3pAAI. Preliminary values of clarity and intelligibility for small writtento extractthis datafrom the LD2900 and processit into C80, D50, auditoria,meeting, and teleconferencerooms. AngeloJ. Campanella andTCT values.Experimental values were obtained in tendifferent rooms (CampanellaAssoc. & ACCULA[I, 3201 P.ldgewood Dr., Columbus,Oil including auditoflum, church, theater,lab, chapel, gym, music, rehearsal, 43026) teleconference,and living rooms. Room qualities varied from good throughthose in needof correctionfor the intendedroom use. Measured Clarity (C80) and intelligibility(D50), normallymeasured for large quantitieswere compared with opinionson existingroom performance to auditoria,provide an alternative to reverberationtime (RT60) to evaluate providepreliminary desirable ranges of C80, D50, andTCT accordingto theacoustical performance of manycritical smaller rooms. A LarsonDavis room use. 3337 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3337 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 1:05 uponthe amountof absorpfion,the center frequency wavelength and/or the dimensions of the absorber are used to determine the size of nonuniform 3pAA2. Spatial selectivity of differentia microphone arrays in regionsin the enclosure.The studyis conductedusing classical modal rectangularenclosures, Ea-Ee Jan and James L. Flanagan (CAIP Ctr., analysis.The resultsprovide physical insight into the behaviorof acoustic RutgersUniv., Piscataway, NJ08855-170) fields in enclosures. Omni-din•tionalmicrophones have been employed in delay-and-sum beamformersto mitigateroom reverberationand ambientnoise. A one- 1:50 dimensionalbeamformer has spatialsolectivity in only one dimension. Therefore,higher-dimensional arrays are usedto improvespatial selectiv- 3pAAS. Visualization of acoustic scattering in a three-dimensional ity. In comparison,a singledifferential microphone provides fixed spatial enclosure, Sylvia K. Islet, Vardhani Harpanahalli, and Charles selectivity.This reportdiscusses the performanceof arraysof differential Thompson (Ctr. for Advan. Cornput.,Univ. of Massachusetts,One microphones.To computesound behavior in the enclosure,calculation of UniversityAve., Lowell, MA 01854) the incidentangle for every arrivingsignal is required.An imagemodel Frequentlythe resultsof time-varyingcomputer simulations of acous- usingthe ray-tracing method has been developed tocalculate the muMpath tic behaviorin built environmentsare difficult to analyzedue the multidi- in an enclosureup to a prescribedorder of images.Nonuniform wall reflectivitiescanbe included. For the special case of rectangularenclo- mensionalnature of the numericalresults. Graphical displays of acoustic datahave been effective in remedyingthis problem.A techniquefor visu- sures,the algorithm efficiently calculates the incident angie for eachar- alizingthe time evolution of a soundpressure field within an enclosuredue riving signaland all of its associatedreflection points. Additionally, it is to a sourcelocated in the enclosureis presented.The numericaltechnique notedthat the numberof imagesfor a givenorder more nearly resembles for computingthe pressuredistribution within the enclosureemploys the anarithmetic series instead of a geometricseries. IResearch supported by methodof images.Pad6 approximants are used to takeinto consideration NSF GrantNo. MIP-9121541and NSF Subcontract397-26740.] the effectsof soundscattering under high-contrast conditions. The graphi- cal representationof the enclosureis createdas follows.The walls of the 1:20 enclosurea0, d objectscontained therein are renderedwith the standard radiositymethod. The graphicaldisplay of the interactionof the pressure 3pAA3, An infinite impulse respame model for sound travel in a field with the enclosureand its contentswas accomplishedby rendering small conferenceroom, Paul S. Kovitz (2877 S. BuchananSt., #A2, eachvolume element in thefield accordingto the pressuremagnitude. The Arlington,VA T2206) presentationwill includea sequenceof imagesdepicting the time evolution A newmethod for predictingan infiniteimpulse response (IIR) froma of the pressurefield in the enclosure. sourceposition to a receiverposition in a smallrectangular room is pro- posed.The methodpredicts the FIRfor all frequenciesbelow an arbitrary 2:05 cutoff.The IIR is statedin termsof a z-transformpolynomial; the orderof thez-transform polynomial follows directly from the room dimensions and 3pAA6. Design and construction of an academic acoustics the cutofffrequency. The effectivenessof thismodel is demonstratedfrom laboratoryat CCNY on a limited budget. SamuelMusora (Dept.of measurements. Mech. Eng., The Cooper Union, 51 Astor P!., New York, NY 10003), DanielR. Raichel (TheCooper Union and the Graduate Ctr. of City Univ. 1:3.$ of New York), Latif liji, and Karim Abdulla-A!taii (CCNY) Establishingan acousticslaboratory from the start on limited funds 3pAA4. Effects of absorptionplacement on interior noise levels•A theoreticalstudy. DanielleS. Labrozziand Linda P. Franzoni (North ($50 K) for the purposeof trainingengineering students constitutes a CarolinaState Univ., Ctr. for Soundand Vib., Dept. of Mech. andAerosp. formidabletask that requires careful planning and design. Cost consider- Eng.,P.O. Box 7910, Raleigh, NC 27695-7910) ationslimit the sizeof an artecholechamber, but fortunatelya commer- cially readyunit was foundavailable for the priceof $15 K and with a The effectof the spatialdistribution of absorbingsurfaces on the sound cutofffrequency of 125 Hz. A reverberationchamber could be constructed field in enclosuresis investigated.For a givenoverall level of absorption, in-housewith the incorporationof a reflectivedoor whichis alsoavailable the differencebetween distributing the absorptionuniformly or localizing commercially.The preferred minimum room volume of 7062ft 3 results in it in a singleregion is studied.Attention is focusedon the high-frequency a cut-offfrequency of 125 Hz. In the selectionof instrumentation,advan- range havingwavelengths small comparedto the enclosuredimensions, tage was taken of the ready availabilityof task-specificcircuit boards but either largeor small comparedto the absorptiveregion. The distribu- whichcan be insertedinto microcomputerswhich can thenserve as • tion of mean-squarepressure in a bandwidthis studiedto ascertainthe analyzersand signals generators. Other equipment include a Class1 sound degree of uniformity throughoutthe enclosure,and particularlyin the levelmeter kit, a numberof extremelylow-priced SLMs, audio amplifiers, vicinityof the absorbingregion. Of specialinterest is the effectof absorp- monitorspeakers, measurement microphones, and an X- Y plotter.Also, the tion on intensificationzones, which are theregions near boundaries where availablespace was reconfiguredto minimizeoutside interference and to thereis a high degreeof spatialcorrelation between modes. Depending maximizethe easeof facilityusage. 3338 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of Amedca 3338 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp THURSDAY AFTERNOON, 1 JUNE 1995 MEETING ROOM 3, 12:30 TO 3:15 P.M. Session3pEA EngineeringAcoustics and Noise:Active Control of Noiseand Vibration II Kenneth A Cunefare, Chair Schoolof MechanicalEngineering, Georgia Institute of Technology,Atlanta, Georgia30332-0405 ContributedPapers 12:30 (bothin theendcap and cylinder wall) forcinghigh interior acoustic levels as well as structural-borneenergy coupling into "rigid wall" cavity reso- 3pEA1. An adaptive feedback technique for disturbance rejection: nances.Wave-number domain analysis reveals the evidenceof free waves Experimentalresults. DanielH. Miller andWilliam T. Baumann (Dept. on the cylindermodified by finitelength effects, flexural Bloch waves, and of Elec. Eng., Virginia PolytechnicInst. and State Univ., Blacksburg,VA couplingto the cavity resonances.In this paper,results are presentedof 24061) active control simulationsthat employ novel control approachesthat are The paperpresents experimental results of a hybridcontrol technique wave-number-domainbased. These results also showthat global accessto thatblends traditional fixed feedbackcontrol with adaptivefeedback tech- low-orderinterior modes is obtainedthrough simple actuation schemes and niques.The objectiveis to providedamping for transientdisturbances via that minimization of some of the more dominant interior modes is achieved the fixedpart of thecontroller and rejection of steadydisturbances via the by the applicationof simpleconstraints to the structure. adaptivepart of thecontroller. This techniquediffers from the other hybrid techniquesin that it doesnot requirea measurementof an externalsignal coherentwith the disturbance,nor doesit requireknowledge of how the 1:15 disturbanceenters the system.In addition,it providesdamping to the system,unlike neutralization-looptechniques. As with all feedbacktech- 3pEA4. Active control of acousticimpedance with a multi-element niques,stability is an issue.The adaptivecontroller is implementedin such system. Brian H. Houston,Douglas M. Photiadis,J. A. Bucaro,Robert a way as to minimizestability problems and in the caseof perfectsystem D. Corsaro (Naval Res. Lab., Washington,DC 20375-5350), and identificationit is guaranteedto be stable.The experimentalresults are LarryA. Kraus (SFA, Inc., Landover,MD 20785) from a cantileverbeam with piezoceramicactuators and sensors.The re- sultsfor the fixed feedbackcontroller will be comparedto thosefor the The use of active controlof acousticimpedance is of generalinterest adaptivefeedback control technique. The comparisonwill includeresults due to a variety of potentialdefense and civilian applications.These in- from harmonic,narrow-band, and broadbanddisturbances. [Work sup- clude control systemsto minimize aircraft and rocket payload section portedin partby ONR contractN00014-92-J-1170.] interioracoustic levels. Control of impedanceat a boundaryis oneof the mostchallenging in active controldue to the collocationof sensorsand 12:45 actuators(implicit in thisis feedbackcontrol). Some of thetechnical issues 3pEA2. Acoustic absorptivity of direct acoustic rate feedback include--theselection of the appropriatephysical control law, the degree control. DanielG. Cole (AdaptiveTechnologies, Inc., 620 N. Main St., of inter-connectivity(local versusglobal control),device linearity, com- Ste. 306, Blacksburg,VA 24060) and William R. Saunders(Virginia ponentand processor delays, system identification, nonminimal phase-zero PolytechnicInst. and StateUniv., Blacksburg,VA 24061-0238) constraintsthe coupling matrix, and performanceversus robustness tradeoffs.Recently, new active boundary control (ABC) experimentswere The fixed-gainfeedback methods often provide the only meansof carriedout at NRL's Laboratoryfor StructuralAcoustics on a 15-tile array limiting transientnoise and excessivesound pressures due to unmeasur- system.The resultsof theseexperiments will be discussedwith a focuson able, incoherent disturbances.The use of direct acoustic rate feedback the applicationof H• controlengineering techniques and the physicsin- (DARFB) to controlan enclosure'sreverberant energy has the benefit over volved. otherfeedback methods of largerstability margins and improved stability robustness.It also provides a meansfor achievingacceptable sound pres- sure levels in locations and environments which are not suited to surface treatmentsof soundabsorbing materials. The effect of DARFB on the 1:30 growthand decayof soundin enclosuresis investigatedand the changein 3pEA5. The impact of sampling location on the minimization of the reverberationtime of a soundfield is discussedfor active absorption noise in a cavity with flexible walls. KennethA. Cunefare,Van Biesel usingsingle and multiplecontrollers. Various models for the dynamicsof (GeorgeW. WoodruffSchool of Mech. Eng., GeorgiaInst. of Technol., soundgrowth are used and are shownto provideequivalent or similar Atlanta,GA 30332-0405),and StevenEngelstad (LockheedAeronaut. results.Effective Sabineabsorption coefficients are shownfor active ab- SystemsCo., Marietta,GA 30063) sorptionand are comparedwith soundabsorbing materials. The effective- nessof transducerplacement is alsodiscussed with respectto activeab- Many transportationsystems, e.g., aircraftand automobiles,have sig- sorptionand the closed-loopreverberation time. Numericalexamples of nificant interior noise levels. There is substantial interest to reduce such acousticabsorption are givenfor a rectangularenclosure. interiornoise levels, while minimizingweight penalties. Since the noise 1:00 field insidesuch vehicles cannot, in general,be determinedanalytically, numericaltechniques are commonly used to modelthe structural response 3pEA3. A novel active control approachfor aircraft interior noise. of the cavitywalls and the accompanyingcoupling to the interiorspace. Brian H. Houstonand Martin H. Marcus (Naval Res. Lab.. Washington. These approaches may then be coupled to an optimization algorithm to DC 20375-5350) determinehow the walls shouldbe designedso as to minimizethe interior The resultsof numericalexperiments carried out to studythe broad- noise.However, a significantfeature of suchan approachis the needto band structuralacoustics of an aircraft-like shell under point excitation samplethe interior field at a numberof pointswithin the volume.This havebeen previously reported. The dominantmechanisms that lead to the presentationwill evaluatehow the distributionof the samplingpoints enhancement of interior acoustic levels are resonances in the structure withina volumemay influence the efficiency of an optimizationalgorithm. 3339 d. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3339 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp The relativemerits of samplingpoints distributed throughout the volume proper procedureto determinethe minimum of this cost function.The will be comparedto pointsrestricted to a layernear the cavity boundaries. main disadvantageof usingsuch a stochasticgradient technique while The subjectcavity will be a simplemodel of an aircraftfuselage. searchingthe prescribedcontrol surface is convergingto localminima. A resolutionto thisproblem is discussedwhich incorporates using a variety of initializationconditions. Two scenariosare consideredhere: grouping 1:45 actuatorsbased upon weightsdetermined by convergingthe filtered-x 3pEA6. On the use of quadratic boundary elementsfor sensitivity LMS algorithmand simultaneouslygrouping and controllingwith the analyses. KennethA. Cunefare (GeorgeW. WoodruffSchool of Mech. compensatorweights startedat zero. Computer simulationsdemonstrate Eng.,Georgia Inst. of Technol.,Atlanta, GA 30332•0405) the abilityof thisnew form of the costfunction to simultaneouslygroup actuators and control the structure-horne noise with either initial condi- The use of the acousticboundary element method is gaining wide- tions. spreadacceptance. As the BEM matures,new usesfor it are beingdevel- oped.including its incorporationinto designoptimization and activenoise controlalgorithms. The useof quadraticshape functions in the BEM for- mulation providescertain benefits with regard to modeling and surface representation.However, these popular elements do posechallenges when 3pEA9. Vibration signature monitoring using analytical models of acousticsensitivity information is desiredof the formulation,such as is slotted beams. XiuTing C. Man and Robert D. Finch (Mech. Eng. usedin optimizationand active noise control. The difficultyarises from the Dept.,Univ. of Houston,4800 CalhounRd., Houston,TX 77204-4792) implicationsof a positivechange in a nodalvalue (e.g., surface normal Vibrationsignatures may be usedin monitoringstructural integrity. A velocity),and the net change over the balance of theelement. Corner nodes procedurewas established in whichthe experimentaldata were processed will yield a net negativechange, while mid-sidenodes will yield a net usinganalytical models of thephysical structures. Steal beams were used positivechange, both for positivenodal change. This presentationdemon- as examples.Saw-cut slots of differentsizes and locationswere the "dam- stratesthat the use of quadraticelements requires careful treatmentas a age" to be deleeted.An analyticalmodel based on a perturbationmethod consequenceof this behavior,and that element-based,rather than node- was developed,which leadsto direct relationshipsbetween the modal based,sensitivities are mostappropriate with this element. propertiesand the slot parameters.The modalfrequencies were estimated experimentallyusing modal analysis techniques. The frequencyreductions 2:00 were computedas the differencebetween the experimentallyestimated modalfrequencies and the valuestheoretically calculated from a uniform 3pEA7. Simultaneous active/passive control of extensional and beam of identicalconditions. The first three modal frequencycontours flexural vibrations in infinite thin beams. Florence L. Deneufve and werecalculated from the perturbationmodel and usedto quantifythe slot Chris R. Fuller (vib. and Acoust.Labs., Dept. of Mech. Eng., Virginia depthsand slot locations.The slot locationswere determinedwith great PolytechnicInst. and State Univ., Blacksburg, VA 24061-0238) accuracy,although the slot depthswere estimatedlower than the actual values.The reasonwas that the perturbationmodel predicted the modal Passivecontrol techniques implemented using added damping, through mass discontinuities or material discontinuities in order to minimize struc- frequencyshifts smaller than the actualvalues, and whenused inversely, it tendedto give a slot depth of higher value. turalvibrations, m-e limited concerning the amountof attenuationobtained especiallyin the low-frequencydomain. Active controlmethods are effec- tive for optimallyreducing structural vibrations, but may requiresignifi- 2:45 cantcontrol energy, especially for largedisturbance inputs. The combina- tion of passivewith active controlhas much potentialfor completely 3pEA10. Active control of vibration of a magnetic levitation reducingvibrations propagating in structuresas the controlenergy required platform. JiangxiongLi, fiaqiangPan, and Qiang Hu (Dept.of Mech. for the active part is found to be reducedand the fi'equencyranges of Eng.,Zhejiang Univ., Hangzhou 310027, People's Republic of China) operationsare complementary.In this research,passive and activetech- niquesare combinedto controlsimultaneously extensional and flexural A studyon activecontrol of vibrationisolation of a magneticlevitation motionsin an infinitethin beam.The passivecontrol is implementedwith platformused for the calibrationof precisiouinertia instruments is pre- a hard rubber discontinuityof variouslengths and the active control is sentedin thispaper. Nonlinear and linearized dynamic models of the sys- achievedwith two co-locatedindependent piezoelectric actuators bonded tem in state-spacewere deduced by usingthe theory of an electromagnetic on each side of the rubbersection. The disturbanceis a harmonicpoint field.The stabilityof boththe open-and closed-loop system was investi- force applied at the origin at an angle in order to excite both extensional gatedin the casesof differentconfiguration of the currentcoils. A LQG and flexural vibrations.The optimal control voltagesare calculatedto optimal control strategywas employedin the control synthesesof the reduceboth the extensionaland flexural wave amplitudesto zero down- magneticlevitation system, since the systeminput perturbanceis a sto- streamof the rubberdiscontinuity. Results of a simulationon an infinite chasticexcition acting on the fixed basefrom the ground.The fransfor thin beam are presentedand discussed. functionsfrom the excitingcurrent or the controlcurrent or the basedis- placementto the vibratorydisplacement of the levitationplatform were verifiedexperimentally. Open- and closed-loopvibration responses were 2:15 calculated.The resultsshow that comparedto the basedisplacement, the vibrationof the magneticlevitation platform can be attenuatedmore than 3pEAS.The use of neural networksfor optimumactuator grouping 20 dB by usingactive control, over frequencies ranging from 0.1 to 10Hz, in time domain active control applications. G. Clark Smith, Chris R. which cover the main peaksof the groundperturbance. Fuller (Vib, andAcoust. Labs., Dept. of Mech.Eng.. Virginia Polytechnic Inst. and State Univ., Blacksburg,VA 24061-0238), and Richard J. Silcox (NASA LangleyRes. Ctr., Hampton,VA 23õ65-0001) Previouswork has demonstratedthe benefitof groupingactuators to 3pEAll, Method of prognosticnoise and vibration from industrial decreasethe numberof degreesof freedomin an activecontrol system. In setups. AlexanderE. Ekimov,Vladimir A. Tyutin (Inst.of Appl.Phys., this work,a time-domaincost function was developed for ou-lineactuator RussianAcad. of Sci., 46 Ulyanov str., Nizhny Novgorod,603600, groupingand active structuralacoustic control (ASAC) of a simply- Russia),Rostislav A. Dudnik,and Andrei B. Kolpakov(Inst. Arch. & supportedbeam excited with a broadbanddisturbance. Actuators are con- Civil Eng., NizhnyNovgorod, 603600, Russia) slderedgrouped when their compensatersare equal.Therefore, the cost functionpresented here incorporatesa mean-squareerror term relatedto This paperconsiders a methodto determinethe contributionof ribre- the structure-bornenoise and an additionalnonquadratic term whichpe- activeindustrial setups (prior to theirmounting on thebasement) to outside nalizesthe controllerfor differencesbetween respective compensator co- noisesand vibrations. The techniqueoffered is basedon theexperimental efficients.The backpropagationneural network algorithm provides the determination of transfer coefficients of noises and vibrations from outside 3340 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3340 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp sources(acoustic generators and vibrators) into environmental points of an electrocompressorlocated in a separatebuilding near the shop.A vi- interest.The contributionof a setupis determinedby multiplyingvibration bratorgenerating a force from 500 to 6000N in thefrequency range 20-60 andnoise characteristics (measured using an operating analogue setup) and Hz wasused to determinevibration transfer coefficients. The experimental experimentallymeasured transfer coefficients mentioned above. The tech- estimationsshowed that electrocompressornoises and vibrationswill not nique was used to estimatethe levels of vibrationsand air noisesat the affect the operationof precisiondevices in the shop.The prognosiswas shop of microelectronicsat the CommunicationEquipment Plant in fully verified by measurementstaken after electrocompressormounting Nizhny Novgorod.The vibrationsand noisesin questionwere causedby and the noisesand vibrationsdid not exceedbackground ones. THURSDAY AFTERNOON, 1 JUNE 1995 GRAND BALLROOM SOUTH AND CENTRAL, 2:15 TO 3:20 P.M. Session3pED Education in Acoustics: Internet and the World Wide Web Lawrence R. Rabiner, Chair AT&T Bell Laboratories,Room 2D-538, Murray Hill, New Jersey07974 Chair's lntroduction--2:15 Invited Paper 2:20 3pED1. The evolvingInternet. PatParseghian (AT&T Bell Labs.,Room 2C-472, 600 MountainAve., P.O. Box 636, MurrayHill, NJ 07974-0636) The WorldWide Web andpoint-and-click browsers have revolutionized the way onelooks at the Internet.The Internetis notjust for computerscientists anymore--it links elementary schools, businesses, and homes around the globe. Addresses for resourceson the WorldWide Web appearin nationalmagazines, local newspapers, and are televised on the eveningnews. Following a brief overview of the Internetand traditional text-based Internet services, this presentationwill focuson emergingmultimedia uses of the Internet. Multimediaextensions for electronicmail allow us to shareimages and sounds. The MBone(Multicast Backbone) supports collabo- ratire toolsfor audioand videoconferencing, as well as a sharedwhiteboard. On the World Wide Web, one can look at the weather report,read colleagues' technical papers, go shopping,and check the traffic conditions, all beforeleaving home for theoffice! While the Internetis strainingto accommodateits escalatingload, advances in networkingtechnology promise a brightfuture. 3341 J. Acoust.Soc. Am., Vol. 97, No.5, Pt. 2, May1995 129thMeeting: Acoustical Society of America 3341 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp THURSDAY AFTERNOON, 1 JUNE 1995 GRAND BALLROOM SOUTH AND CENTRAL, 1:00 TO 2:05 P.M. Session3pID Interdisciplinary: Hot Topicsin Acoustics Yves H. Berthelot, Chair Schoolof MechanicalEngineering, Georgia Institute of Technology,Atlanta, Georgia 30332 Chair's Introduction•l:00 A specialsession on "Hot Topicsin Acoustics"is presentedat eachmeeting of theSociety. A memberis chosenfrom each of three or fourof the Society'stechnical committees or specialtygroups to presenta rotoralpaper on topicsof currentspecial interest. The presentationsare intendedto helpacousticians become familiar with issuesand achievements that are not withintheir own primary fields of interest. Invited Papers 1:05 3plDl. Hot topicsin structuralacoustics. Andrew N. Norris(Dept. of Mech.Eng., Rutgers Univ., Piscataway, NI 08855-0909) This talk surveyssome key developmentsin modelingthe acousticresponse of fluid-loadedstructures. Recent experimental and computationalresults indicate that wave interaction effects are very significantfor structureswith evena smalldegree of complexity. The complexitycan be as simpleas a few ribs or stiffeoerswhich convert supersonic membrane-type wave motion into subsonic flexuralenergy, and vice versa.A greatdeal of effort continuesto be put into developingefficient numerical methods in orderto simulategreater complexity. At the sametime, recent analytical findings have increased our understandingof the dynamicinteraction at ribs and platejunctions, in termsof wave-likediffraction processes. Ray methodshave been developed to handlethe multi-wave natureof structuralenergy flow on nonseparableshapes, and providea fast numericalmethod for dealingwith high-frequency simulation.In general,the complexityof the substructureswithin the relatively well-defined"master" structurepresents the most difficultchallenge for modelers.Techniques are only now beingdeveloped to distinguishthese effects in a logical manner.One approachof greatinterest is "fuzzy" structuralacoustics. The idea is to replacethe detaileddynamics of the internalby a smearedout effect,which still containssome of thephysics of the internalsuch as the total mass, and the modal density per unit bandwidth. Fuzzies are also "hot" in that they are guaranteedto generatethermal energy among ASA participantsconcerned about energy effects. 1:25 3plD2. Hot topicsin speechconununicafion. D. H. Whalen (HaskinsLabs., 270 Crown St., New Haven,CT 06511) In speechprocessing, mapping from acousticsto articulationis becomingmore useful. While acousticallybased recognizers have achievedimpressive success rates, their limitationsdo not seemto be yieldingto furtheracoustic manipulations. Recovering the articulationunderlying the speechoffers a way of decodingthe complexacoustic manifestations of simplearticulatory events. These resultsalso offer benefitsin bit-ratereduction and speechsynthesis. In speechproduction, nonlinear dynamic models of speech articulationare beginning to bearfruit. The transition from stasis to vibrationof thelarynx (the voicing source in speechand singing) canbe viewed as a switchfrom a pointattractor (damped oscillator) to a limitcycle (self-sustained oscillation). The tools of nonlinear mathematicsand chaos theory allow us to exploresuch topics as voice breaks, yodeling, and certain voice disorders, as well asnormal phonafion.Nonlinear techniques have also provided important insights into the productionmechanisms of fricativeconsonants. In speechperception, one of themost interesting new developments is the paRems of brainactivity (seen in bloodflow) shown by PET scansand by functionalMRI. Researchershave foundthat passivelistening to speechactivates the temporallobe, but making judgmentson thatsame speech also involves Broca's area. Reading print also activates Broca's area, indicating a cruciallink between apcc•h and rc•tding.Another finding is that males r•ly mostly on the left premotorcortex in performingphonetic tasks presented in print,while females are not strongly lateralized. As acquisitiontime declines, fMRI promisesto yieldeven more specific information on speechperception. 1:45 3plD3.Hot topicsin underwateracoustics. W. A. Kuperman(Marine Phys. Lab., Scripps Inst. of Oeeanogr.,Univ. of California, SanDiego, La Jolla,CA 92093-0238) Underwateracoustics is in a periodof renaissancewith researchers actively pursing studies in manyareas from short-range high-frequencyshallow water acoustics to globallow-frequency acoustics. There has been renewed interest in inhomogeneous sedimentacoustics as well as propagationin very shallowwater bounded by thesesediments. The recentOffice of Naval Research "SRP" programstudying deep water boundary reverberation has not only been fruitful. but hasalso laid thefoundation for innovative 3342 J. Acoust.Sec. Am., VoL 97, No.5, Pt.2, May1995 129thMeeting: Acoustical Society of America 3342 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp researchin thearea of boundaryscattering in coastalwater acoustics. On theother scale, the Heard Island Feasibility Test as described by 18 papersin theOctober 1994 issue of JASAhas re-awakened interest in the myriadof possibilitiesof monitoringall scalesof the oceanusing acoustic methods. In an expandingnumber of efforts,underwater acoustics is distinguishingitself as developingthe most physicallybased signal processing schemes presently being considered in any field.These and other hot topicswill be discussed. THURSDAY AFTERNOON, 1 JUNE 1995 MEETING ROOM 2, 1:00 TO 3:15 P.M. Session3pNS Noise: Noise and Hearing Linda L. Pierson, Chair Visualand AuditoryProcesses Branch, Human Researchand EngineeringDirectorate, U.S. Army ResearchLaboratory, AberdeenProving Ground, Maryland 21005-5425 ContributedPapers 1:00 presentationswas increased for bothblast wave sources. There were, how- ever, consistentdifferences between the effectsof the low- and high- 3pNS1.Investigation of the impactof changesin regulatorycriteria frequencyenergy "content" blast waves. Correlations between the depen- on the ,dailynoise dose (DND) of longwallcoal mine workers, J. dent variables and the energy of exposurewere highest for P- or AltonBurks and Roy C. Bartholomae(U.S. Bureauof Mines,Pittsburgh A-weightedenergies [Patterson et al., J. Acoust.Soc. Am. 93, 2860-2869 Res.Ctr., Pittsburgh,PA 15236) (1993)].[Work supported by U.S.Army Medical Research and Develop- The authorspreviously examined the impact of anticipatedchanges in mentCommand.] noiseregulations on the coal mining industry [R. C. Bartholomaeand J. A. 1:30 Burks,Noise-Con 94, 1017-1022(1994)]. That analysis focused primarily on assessingthe effecton the daily noisedose (DND) resultingfrom 3pNS3. Validating a mathematical model of noise hazard with changingthe currentthreshold level from 90 to 80 dBA. To morefully varying numbersof roundsand peak pressuresproduced by a rifie• explor%the effect of otherregulatory parameters, aswell as the threshold G. RichardPrice, Linda L. Pierson,Joel T. Kalb,and Pain Mundis level, 59 setsof full-shifttime-resolved dosimeter data were acquiredon (HumanRes. and Eng. Directorate, Army Res. Lab., Aberdeen Proving four occupationsassociated with longwallcoal mining.After thesedata Ground,MD 21005) weredownloaded to a computer,realistic combinations (a totalof 12) of criterionlevel (80, 85, 90 dBA), thresholdlevel (80, 85, 90 dBA), and A mathematicalmodel of noisehazard [G. R. Priceand J. T. Kalb, J. tradeo.ff rate (3, 5 dBA) wereapplied to thesedata to computeDND's. The Acoust.Soc. Am. 90, 219-227 (1991)] hascorrelated very highlywith resultsof this "what if" type analysisare presented.In generalit was heatingloss to 50 Friedlanderimpulses from two sourcesat 5 different concludedthat the magnitudeof the computedDND resultingfrom peakpressures (135 to 145 dB). In orderto extendthe model'srange four changesin eitherthe tradeoffrate or the thresholdlevel is unpredictable; additionalnoise exposures were tested: two single impulse exposures (157- instead,it dependson the specificdistribution of noiselevels associated and169-dB peak) and 6 or '12impulses at 143-dBpeak pressure. These with a given worker'snoise exposure. specificconditions were alsochosen to contxastthe model'spredictions with the "CHABA" damagerisk criterion(DRC). Four groupsof ten anesthetizedcats were exposed to eachcondition and ABR thresholdsat 1, 2, 4, 8, and 16 kHz were monitoredto establishhearing loss immediately and 2 monthslater. In eachcase the model'spredictions were upheldand 1:15 rankingsof hazardby theCHABA DRC wereno[ Furthermore,no simple 3pNS2. The effects of reverberant blast waves on hearing: Energy linear frequencyweighting would have predictedthe losses.The model's and spectralconsiderations, William A. Ahroon,Sheau-Fang Lei, and hazardrating correlated well with the grouphearing losses (coefficient RogerP. Hamernik (AuditoryRes. Lab., StateUniv. of New York, near0.8) andrefinement of themodel's annular ligament and the intraco- Plattsburgh,NY 12901) chlearhazard formula is expectedto improvethis correlation. Chinchillaswere exposed to 1, 10, or 100reverberant impulses at 150, •: • 1:45 155,or 160 dB peakSPL. The impulseswere generated by one of two 3pNS4.Effect of "conditioning"on hearingloss from military noise differentshock tubes each producing blast waves having a d,ifferent spec- tral composition;one emphasizing low frequencies(<0.5 kHz), the other exposures.Lynn W. Hen..selman (Army Audiol. and Speech Ctr., Walter Reed Army Med. Ctr., Washington,DC 20307-5001), Donald mid-frequencies(2-4 kHz). Impulseswere presentedat the rate of l/s. Henderson,Malini Subratnaniam, Philip Hofstetter (SUNY, Buffalo, NY This parametricparadigm yielded 18 exposureconditions; 15 animals/ 1A9A•.),•nd IJina•n•t• •allu•tio (C•ntra Di Audiolagiea,Uniuer•ita Di condition.Heating thresholdswere measuredusing auditory evoked po- Bari, Bad, Italy) •. tenrialsand the sensoryepithelium was evaluatedwith the surfaceprepa- ration. In general,trauma increased as the total energyof the exposure, It hasbeen shown with chinchillas assubjects that prophylactic ("con- determinedby the peak SPL and numberof presentations,increased. The ditioning")exposures to an interruptedOBN centeredat 0.5 kHz for 10 dependentvariables (permanent threshold shift and sensory cell loss)v at- daysprovide protectioni•gainst permanent threshold shift(PTS) from high led in an orderly fashionacross frequency as the peak and numberof levelimpulse noise in c.,hinchillas [L.W. Henselman efal. i Hear.Res. 78, 3343 d. Acoust.Soc. Am., Vol, 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3343 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 1-10 (1994)].The presentinvestigation studied the effectof "condition- ing" with helicopternoise on PTS resultingfrom high level impulsenoise. 3pNS7. Mathematical formulas and summary measures for the Thirty-eightchinchillas were randomly assigned to oneof fourexperimen- tal groups(helicopter noise exposure prior to impulsenoise exposure) or a audiometric database analysis procedures (ANSI S12.13-1991). controlgroup (impulse noise exposure only). It wasshown that (a) inter- Tilahun Adera (DepL of PreventiveMedicine, Medical College of Virginia, 1008 EastClay St., Box 980212, Richmond,VA 23298) cuptedexposures over a 10-dayperiod to helicopternoise presented at 112 dB SPLfor 1.5 h/daycaused 'I'rss to decreaseas exposure days continued The conceptof an audiometricdatabase analysis (ADBA) methodfor at thetest frequencies of 0.5 to 8 kHz, and(b) after4 weeksof recovery, evaluatingthe effectivenessof hearingconservation programs has been subjectswere protected from PTS after "conditioning"With helicopter appearingin the scientificliterature for morethan 15 years.This concept noise(except the group with prolonged "conditioning"). Histological re- wasrecently developed into a seriesof proceduresand is currentlybeing sultswere consistent with aUdiological findings and reveal •ed significantly consideredfor acceptanceas a U.S. NationalStandard (ANSI S12.13- lesshair cell lossin the experimentalgroups that were protectedfrom PTS. 1991}.Although the methodpresents the variousanalytical procedures in The resultsare discussedin termsof possibleapplication to hearingcon- a narrativefashion, mathematical formulas expressing the essentialprin- servationprograms. [Work supported by the U.S. ArmyMedical Com- cipleshave not been provided. In addition,there currently is no methodfor mand.] determiningthe overalleffectiveness of a hearingconservation program (HCP) followingapplication of ADBA proceduresto a setof audiometric data.This paperprovides the mathematicalformulas for fourADBA pro- ceduresincluding the percentworse sequential, percent better or worse sequential,standard deviation applied to singletest frequencies, and stan- 2:00 dard deviationapplied to averagesof test frequencies.In addition,the 3pNS5. Comparisonof impulsenoise effects generated by two rifle paperintroduces and illustrates two methodsof summarizingresults from muzzles. Linda L. Pierson, G. Richard Price, loci T. Kalb, and Pamela ADBA procedures,which includesthe standardscore estimator and the A. Mundis (Visualand Auditory Processes Branch, Human Res. and Eng. scoredesignator. Each of thesemethods consists of at leasta medianand Directorate, U.S. Army Res. Lab., Aberdeen Proving Ground, MD a mean-basedprocedure. The strengthsand limitationsof theseprocedures 21005-5425) in determiningthe overalleffectiveness of an HCP are discussed. The currentimpulse noise standard for US military usesa combination of peaksound pressure level and envelope duration to ratehearing hazard. There is generalagreement that this proceduretends to overestimatethe 2:45 hazardfrom impulsesthat are broadlypeaked at the low frequencies.One 3pNSS.A comparativestudy of occupationaland nonoccupational possiblecorrection would be to frequency-weightthe energy,giving less noiseregulations in SouthAmerican countries. Jorge P. Arenas (Inst. emphasisto the low frequencies.The currentstudy, using the cat as a of Acoust.,Faeultad de Cienciasde la Ingenieria,Univ. Australde Chile, model,compares the physiologicaleffect (auditory brainstem regponse Casilla567, Valdivia,Chile) and MalninGutierrez V. (Inst. of Aconst., threshold)of onerifle impulsegenerated either with the standardor an Univ. Australde Chile, Casilla 1130,Valdivia, Chile) experimentalmuzzle device. The pressurefrom the standardmuzzle device (N=9) (157.1dB Peak, 9.62 ms B-duration, 0.9 J/M 2) has a peak13 dB The final aim of this work is to show a comparativestudy about the "below" the pressuregenerated by the experimentalmuzzle device (N mostimportant aspects of the noiseregulations in someSouth American =10) (169.9dB peak, 6.88 ms B-duration, 9 J/M2). It wouldbe expected countries.It includesArgentina, Brazil, Chile, Peru, and Uruguay.Where that the animalsin the normal muzzle group would incur substantiallyless nationalstandards exist in a particularcountry, the areaof application,and thresholdshift than animalsin the experimentalmuzzle group. However, otherdetails of the procedures,should be in accordancewith the standards groupmean threshold were not significantlydifferent. This findingchal- of thatcountry. The differencesbetween national slandards are extremely lengesthe currentcriterion. Furthermore, although both impulsescontain significantfor sometypes of noise.The mostimportant parameters for essentiallythe samespectrum, because the energycomposition of the im- nonoccupationalnoise considered when assessingthe acceptabilityof a pulseswas very different,frequency weighting alone does not solvethe givennoise exposure are: the time of the day (day time,evening, night problem. time), the type of neighborhood,the useto whichan areaof land or buildingis put, and sometimesthe indoorstandards. The basiccriteria is not to alter the character of an entire area and dominate its noise climate. In somecountries the occupationalregulations are combinationsof ISO and OSHA standards. Differences were noted in some dose criterias and 2:15 the trade-offbetween noise level and permittedexposure time is still the subjectof somedivergence of opinion.Some standards allows 3 dB (or 5 3pNS6. The effect of the level of impact noise on hearing loss. dB) increasein noiselevel per halvingof exposureduration. StephanieLevine, Donald Henderson, and Phillip Hofstetter (Hear.Res. Lab., Univ. of Buffalo,Buffalo, NY 14214) impulseand impact noise found in industrymay be particularlydan- gerousfor workers'hearing. This studyexamines the effect of the levelof 3:00 impactnoise on hearingloss. Twenty four adultchinchillas were exposed 3pNS9. Modified method for determination of heightenedhuman to impactnoise for 7.5 h. The subjectswere divided into four groupsand sensitivityto noise. AlexanderA_ Menghovand Vladimir V_ Lipovoy exposed to impulses delivered at Ils at one of four aifferent intensities: (Inst. for OccupationalHealth, 252033, Kiev, Ukraine) 113, 119, 125, and 131 dB. As the level of exposl•reincreased, the perma- nent hearingloss of the animalsincreased. At lower levels, 113-125 dB Occupationalhardness of hearingoccurs first of all in workerswith hearingloss increased at approximately1.8 dB for eachdB of noise.These heightenedsensitivity to noise.Along with the objectivemethod for de- findingsare consistentwith studiesusing continuous noise which report a termininghigher excitability of the centralstructures of the auditoryana- 1.7-dB increasein asymptoticthreshold shift for every dB increasein lyzerby meansof theawaked brain potentials, the heightened sensitivity to exposure.However, as the level of the impactincreases beyond a critical noisecan be determinedby a simplermethod [A. Peyser,Acta Oto- level,(125 dB) theresulting threshold shift increases dramatically i.e., 6 laryngol.(Stockh.) 28, 443-444 (1940)].The experimentaldata have dB for eachdB increasein exposurelevel. It hasbeen shown in prior shownthat a higherincrease in TI'S is observedat a toneof 2000 Hz research[Hametalk eta/., Hear.Res. 13, 229-247 (1984) andHenderson insteadof 1000Hz accordingto A. Pcyser.Such a modifiedmethod was et eL, Hear.Res. 76, 101-117(1994)] that the anatomical damage to the approvedat 42 youngweavers. After 3 min of 100-dBnoise load at the cochleaat thiscritical level changesfrom metabolicto mechanical.[Re- toneof 2000Hz in 13%of weavers'IFS wasmore than 12 dB (hightened searchsupported by NIOSH GrantNo. 15034470.] sensitivity).After work for a yearunder the conditions of 98-100 dBA, in 3344 J.Acoust. Soc. Am., Vol. 97, No. 5, Pt.2, •ay 1995 129thMeeting: Acoustical Society ofAmerica 3344 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp the weaverswith hightenedsensitivity, TTS at the tone of 2000 Hz was 2000 Hz was 4.3 dB, and at 4000 Hz was 1.7 dB. In the insensitive to noise 11.9 dB, at the tone of 1000 Hz was 9.4 dB, and at the tone of 4000 Hz was weavers,PTS at 1000 Hz was 1.1 dB, at 2000 Hz was 1.7 dB, and at 4000 9.6 dB. In the weavers insensitiveto noise, 'IFS at the tone of 1000 Hz was Hz was 1.3 dB. The determinationof humansensitivity to industrialnoise 7.0 dB, at the tone of 2000 Hz was 7.5 dB, and at the tone of 4000 Hz was by audiometryin this modificationenables one to discoverworkers with 7.8 dB. In the sensitiveto noise weavers, PTS at 1000 Hz was 2.3 dB, at heightenedauditory sensitivity and predictthe PTS auditorylevel. THURSDAY AFTERNOON, 1 JUNE 1995 AUDITORIUM, 12:40 TO 3:20 P.M. Session3pPP Psychologicaland PhysiologicalAcoustics: Hearing Impairment, CochlearImplants and Hearing Aids Fan-GangZeng, Chair HouseEar Institute,2100 WestThird Street,Los Angeles,California 90057 ContributedPapers 12:40 1:10 3pPP1. Simalation of sensorineuralhearing loss: Use of linear 3pPP3. Relationshipsbetween simple reactiontime and auditory speetraismearing to reducefrequency resolution. ArthurBoothroyd, stimulusintensity in peoplewith sensorineuraihearing losses. BethanyMulhearn, Juan Gong, and Jodi Ostroff (City Univ.of New York, PhilipF. Seitz (Ctr.for Auditory and Speech Sci., Gallaudet Univ., 33 W. 42 St., New York, NY 10036) Washington,DC 20002-3695)and BradRakerd (MichiganState Univ., EastLansing, MI 48824-1212) Phonemeand word recognition, was measured in sevenhearing adults undervarious conditions of spectralsmearing--produced by multiplying Individualdifferences in reactiontime (RT) to subjectivelycomfort- thespeech waveform by low-pass-filterednoise. Phoneme recognition fell able,loud, and soft tones were assessed for ten youngadult subjects with from 97% for no smearingto 13% for completesmearing (-+10 kHz), longstanding,less-than-profound sensorineural hearing losses and ten nor- real hearingcontrols. To supportestimation of the sensory,central, and Smearingby +_600Hz reducedgroup mean phonemerecognition to motorcomponents of RT, subjectswere also testedusing an equivalent 50%--a scoretypical of hearing-impairedsubjects with hearinglosses protocolwith brightand dim visualstimuli. Subjects with normalhearing around80 dB, listeningto amplifiedspeech. In a secondexperiment, noise listenedto 500-Hz tonesat fixedintensities that pilot testing established as wasmixed with thespeech before spectral smearing was introduced. Noise correspondingto comfortable,loud, and soft levels.Prior to RT testing, susceptibilitywas measured as the S/N ratio requiredfor a phonemerec- subjectswith hearinglosses individually adjusted tone intensityto "most ognitionscore that was 50% of the scorein quiet.Smearing at -+1 kHz comfortable,""very loud but not painful," and "very soft but definitely increasednoise susceptibility by 20 dB, an amountsimilar to that foundin audible" levels. Results show larger modality-dependentand level- hearing-impairedsubjects with lossesin excessof 90 dB. As with hearing- dependentindividual differences in RT thanhave been previously noted in impairedsubjects, spectral smearing diminished the perceptionof conso- the literature,pointing up a needfor individualsubject baselines in cog- nant placemore than the perceptionof consonantmanner and voicing. nitive experimentsthat useRT as a dependentvariable. Results also indi- Unlike with heating-impairedsubjects, however, smearing affected vowel catethat the typicallysmall range between threshold and pain in listeners perceptionmore than consonantperception. This last findingmay be at- with heatinglosses is, with respectto RT, functionallyequivalent to larger tributedto theuse smearing over a fixedbandwidth--producing a greater rangesin normalhearing listeners in someindividuals but not in others. percentagesmearing in thelower frequencies. [Work supported by NIDCD [Worksupported by NIH-NIDCD.] GrantNo. 10078.] 12:55 1:25 3pPP2. Loudnessfunctions in normal-hearing and hearing-impaired 3pPP4.The relationshipbetween aided articulation indices, listeners. LidiaW. Lee (Dept.of Commun.Disorders, Northern Illinois performance, and subjective satisfaction with programmable and Univ., DeKalb, IL 60115) and Larry E. Humes (Indiana Univ., conventional hearing aids. Gabrielle H. Saundersand Kathleen M Bloomington,IN 47405) Cienkowski (Audiology(126), VeteransAdmin. Med. Ctr., EastOrange, NJ 07019) This paperexamined whether an excitation-patternmodel of loudness could adequatelydescribe the growth of loudnessfor complex stimuli The ArticulationIndex (AI) wasdeveloped as a methodfor predicting presentedto normal-hearingand hearing-impairedlisteners in quietand in speechrecognition performance from objectivemeasurements. It should noise.The loudness-growthfunctions were obtainedfor threesynthesized thereforebe an efficient method for predictingand comparingpotential steady-statevowels (/a,i,u/), eachwith two talkers(male: F0=120 Hz; user benefit from different hearing aids. In this study subjectswore six female:F0=200 Hz), and for severalpure tones(125-4000 Hz). All differenthearing aid fittingsfor 3 monthseach. Performance on a number stimuliwere presented, at random,from 2 to 90 dB SPL (in 4-dB steps)in of speechtests was measuredat the startand end of each3-month period quietand in broadbandnoise. Magnitude estimation were usedto measure and self-ratedsatisfaction with eachheating aid was assessed.Als for each the loudnessof eachstimulus. These data are usedto evaluatethe predic- hearingaid fitting were calculatedfrom real ear aided gains.The relation- tionsof anexcitation-pattern model [modified power-law model, L. Humes shipbetween the AIs, performance,and satisfaction will be presentedand andW. Jesteadt,J. Acoust.Soc. Am. 85, 1285-1294(1989)]. [Work sup- the efficacyof usingthe AI as a predictorof performanceand satisfaction portedby NIA.] will be discussed. 3345 J. Acoust.Soc. Am., Vol. 97, No.5, Pt.2, May1995 129th'Meeting:Acoustical Society of America 3345 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp prescription.Two prescriptionsbased on theArticulation Index (AI), one 1:4021:50Break on NAL-R, anda controlprescription were evaluated in thetwo week field trial.Subjects rated each algorithm in seven categories. Objective mea- suresof speechintelligibility in noise, including measures of binaural directionalhearing, were taken before and after the field trial. Intelligibility 1:50 anddirectional hearing was best with theAI prescriptions,although these prescriptionsdidnot receive the highest subjective ratings. Details of the 3pPP5.Intensity discrimination of amplitude modulated stimuli in binauralalgorithms and fittings, as well as objectiveand subjective mea- electric hearing. Fan-GangZeng and Robert V. Shannon (House Ear suresof theirbenefit will be reported. Inst., 2100 W. 3rd St., LosAngeles, CA 90057) In cochlearimplants loudness isa power function. ofelectrical ampli- tudeat low frequencies (<300 Hz) and •h exponentialfunction for higher 2:35 frequencies[Zeng and Shannon, Science 264, 564-566 (1994)].In addi- tion, thejust-noticeable-difference (jnd) in intensityis inverselypropor- 3pPP8.Combining ratings and paired comparisons in hearing aid tionalto theslope of theloudness function. Implant speech processors evaluation. Harry Levitt, ArleneC. Neuman,and ChristopherOden (Ctr. for Res.in Speechand Hear. Sci., Graduate School and Univ. Ctr., generallyuse low-frequency modulation of a high-frequencycarrier. Be- cause the loudness functions are different for the modulator and carrier City Univ. of New York, 33 W. 42nd St., New York, NY 10036) frequencies,thisraises the question: Dothe loudness andjnd of a modu- The methodof pairedcomparisons is a rapidand efficient technique latedstimulus followsthe modulator or thecarrier? Intensity discrimination whichhas proven to be usefulin hearingaid evaluation:In the conven- was measuredfor a 100-Hz sinusoidallymodulated 1000-Hz sinusoidor tionalapplication of thetechnique, the subject is limitedto a binarydeci- pulsetrain in implantlisteners. The jnd was measuredeither as an incre- sion.Greater efficiency can be obtainedif, in addition,a confidencerating mentin the carrier level for a fixedmodulation depth or as an it}crement in is obtained.A methodfor combiningconfidence ratings with paired- the modulationdepth for a fixedcarder level. The resultsshowed that the comparisondata is pro¾ided.Data are presented in whicha setof hearing jndfunction of themodu!ated stimuli is similarto the jnd function of the aidsdiffering in compressioncharacteristics (compression ratio, release high-frequencycarrier. Ath!gh sensation levels, implant listeners can dis- time)was evaluated by the traditional paired-comparison technique and the criminateextremely small changes in modulation depth (1%-2%). This paired-comparisonplus rating technique. Data will alsobe presentedon impliesthat modulatedstimuli can producemore jnd stepsacross the therelative precision and efficiency of thetwo techniques. dynamicrange than either the modulatoror the carderalone. 2:50 2:05 3pPP9.Effects of hearingaids on binauraldirectional hearing in 3pPP6. Preliminary evaluations of cocldear implantees using a hearing-impaired individuals. Donna J. Gelnett, Michael J. Nilsson, wearable CIS processor. W. M. Rahinowitz, D. K. Eddington,J. andSigfrid D. Soli (HouseEar Inst., 2100 W. 3rdSt., Los Angeles, CA Tierney, and L. A. Delhorne (Res. Lab. of Electron.,MIT, 50 VassarSt., 90027) Rm. 36-789, Cambridge,MA 02139) Binauraldirectional heating, the ability of a listenerto "tuneout" Eachchannel of a continuous-interleaved-stimulation(CIS) sound pro- noisefrom One direction and listen to a signalfrom another direction, cessoruses the compressedenvelope of its bandpass-filteredoutput to improvess•eech intelligibility in noise.This abilityis presentin the modulatebiphasic current pulses that are deliveredto an intracochlear hearing-impairedindividual, but may be reducedas a resultof hearing electrode. Pulses are interleaved across channels to avoid simultaneous impairment:Thepresent research examined therelationship between aided fieldinteractions, and pulse rates are high (-2000 pps/channel)to preserve andunaided dil:ei•fional hearing, and directional hearing capacity--as mea- temporalwaveform cues. Using up to six monopolarelectrodes directly suredunder headphones with simulatedhead-related transfer functions and accessiblewith the Inetaidimplant, this strategy has shown considerable idealizedamplification. Reception thresholds for sentences(RTSs! were promisein acuteevaluations conducted in the laboratory[Wilson eta!., measuredwith and with6'ut spatial separation of the speech and a spectrally Nature352, 236-238 (1991)].In collaborationwith a groupin Innsbruck, matchednoise for 25 hearing-impairedbinaural hearing aid users.Direc- a prototypeportable real-time system has been developed(based on a tionalhearing capacity for theseindividuals often fell within the normal DSP56001) that can realize some CIS implementations.Two subjects with range.Unaided RTSs were elevated 3-6 dB on averageover the capacity 9 yearsof experienceusing the Inetaid analog sound processor are•now measures.Aided RTSs were also elevated 2-3 dBover averag e scores for wearing the CIS systemon a full-time basis.After severalweeks, one directionalhearing capacity, suggesting that the interaural cues for binaural subjectprefers the CIS strategy;however, objective measures of speech directionalhearing are eitherinaudible or absentfrom the hearingaid receptionshow no gains(re: the Ineraidprocessor). The secondsubject output.Detailed analyses will be reportedwith respect to the typeof showslarge gains with CIS andsome evidence of continuingimprove- hearingaidl hearing aid transfer function, and degree of heatingloss. ments.Without lipreading, he scoresnear perfect on relativelydifficult (IEEE/Harvard)sentences in quiet; for speechreception in noise,he shows a deficitof 7 dB re: normal-hearinglisteners. [Work supported by N1H.] 3:05 3pPP10.Sound localization inthe median sagittal plane by hearing 2:20 impairedli•tener•. grad Rakerd, Timothy J. VanderVelde (Dept.of Audiol.and Speech Sci., Michigan State Univ., East Lansing, MI 48824), 3pPP7. Field trials of a portableprototyp6 digital hearing aid. and WilliamMorris Hartmann (Michigan State Univ., East Lansing, MI DonnaI. Gelnett,Jean A. Sullivan,Michael J. Nilss9n,and SigfridD. 48824) Soli (HouseEar Inst..2100 W. 3rd St.,Los Angeles, CA 90057) Previously,it was reported that listeners with substantial high- A battery-operateddigital processor connected to microphonesand frequencyhearing loss have difficulty localizing sounds in themedian receiverslocated in left and right ear moduleswas built and used in a sagittalplane IVander Velde et al., J. Acoust,Soc. Am. 94, 1812(A) hearingaid field trial. Eight hearing impaired individuals with moderate to (1993)].When asked to localizebroadband noise, they performed near moderatelysevere hearing losses served as subjects. All subjectshad sym- chancelevel on an elevationtask and somewhatbetter, but far below metrichearing losses and were experiencedbinaural hearin• aid users. normal,on a taskthat required that they distinguish between sources to the Fourbinaural hearing aid algorithmswere programmed into the processor front,overhead, and rear. In the presentstudy, these experiments were forevaluation in thefield trial. The algorithms all equalizedthe magnitude repeatedwith new subjects(n=16), and with the followingvariations, andphase insertion effects of theear modules,but differedin theirgain eachintroduced to encourage improved performance. (l) Low-frequency 3346 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt.2, May1995 129thMeeting: Acoustical Society of America 3346 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp componentsof thenoise stimulus were filtered out to precludethe masking groupoverall (p >0.05). Together,these results point up a significantlo- of moreinformative high-frequency components. (2) Thedifficulty level of calizationproblem for individualswith high-frequencyhearing loss of the theelevation task was eased. (3) Subjectswere tested while wearing their sortthat commonly accompanies aging. The resultsalso support the theory hearingaids. Each of thesechanges helped a few individuals,typically in that spectralcues are of the greatestimportance for medianplane local- smallways, but none produced statistically sign;ficant improvement for the ization.[Work supported by NIDCD.] THURSDAY AFTERNOON, I JUNE 1995 MEETING ROOMS 12, 13, 14, 1:00 TO 3:10 P.M. Session3pSA Structural Acousticsand Vibration: Structural Intensity II Sabih I. Hayek, Cochair Departmentof EngineeringScience and Mechanics,Pennsylvania State University, University Park, Pennsylvania16802 JeanLouis Guyader,Cochair LaboratoireVibrations-Acoustique, INSA-Lyon, 69621 Villeurbanne,Cedex, France Invited Papers 1:00 3pSA1.On the useof acousticalholography for thedetermination of intensityin structures.Anthony J. Romano,a)Earl G. Williams,and Charles G. Delvecchioa) (Naval Res. Lab., Code 7132, Washington, DC20375-5000) An overviewof themethods for determiningstructural intensity from information obtained using near-field acoustical holography (NAH)is presented. Toward these ends, a presentationof the theoretical basis and practical methodologies involved in NAH is given, aswell as a briefrestatement of thestructural intensity formulation appropriate for thinshells and plates. A methodfor obtainingthe unknowndisplacement and stress components from a knowledgeof surfacepressure and normal velocity is discussed,and these methodsare appliedto experimentaldata obtained for the particularcases of a point-driven,fluid-loaded rectangular plate and cylindricalshell. A moviewill he presentedwhich displays the instantaneousstructural intensity corresponding to the situations previouslyoutlined. a)Also at Sachs/FreemanAssociates, Inc., 1401 McCormick Dr., Landover, MD 20785. 1:25 3pSA2. Broadbandcontrol of multi-modepower flow in beamsusing wave vectorsensors. G. P. Gibbs,M. Bronzel,C. R. Fuller,J. D. Blotter,D. E. Montgomery,and R. L. West (Dept.of Mech.Eng., Virginia Polytechnic Inst. and State Univ., Blacksburg, VA 24061-0238) Recentwork has demonstratedthe use of wave filteringtechniques to estimatetraveling waves in the time domain.These techniquesuse PVDF surfacemounted sensors in conjunctionwith a digitalfilter networkto estimatethe travelingflexural and extensionalwaves in beamsfor band-limitedspectra. The travelingwave estimates are proportional to thepower flow in thebeam, and thuscan be usedas thecost function of an activecontrol system. In thispaper, experimental results are presentedwhich demonstrate the broadband active control of flexuraland extensional power flow in beamsusing surface mounted piezoceramic control actuators, surfacemounted PVDF wave vector filters, and a TMS320C30 basedadaptive controller. The resultsdemonstrate flexural and extensionalpower flow attenuationsof 5 to 20 dB for band-limitedexcitation. Independent verification of the total beamresponse beforeand after control (three dimensional) is foundvia a techniquecalled experimental spatial dynamics modeling (ESDM). Velocity measurementsfrom a scanninglaser vibrometer are processed using the ESDM techniqueto producea full 3-D velocityresponse field. Thesedata can be furtherreduced using a methodtermed experimental spatial structural intensity (ESSI) to determinethe complex intensityover the beam.Contour plots are presentedshowing flexural and extensional power flow in the beamfor bothuncontrolled andcontrolled cases. [Work supported by NASA LangleyResearch Center.] 1:50 3pSA3. Laser interferometry for structural acoustics. Yves H. Berthelot,Jacek Jarzynski, Hyun-Gwon Kil, Lance Wills, and Ming Yang (Schoolof Mech. Eng.,Georgia Inst. of Technol.,Atlanta, GA 30332-0405) Laser interferometryoffers the possibilityof measuringin real time instantaneoussurface velocities in the /zrrdsrange by noninvasivemeasurements. It can also be used to measurethe three componentsof the surfacevector velocity at several points simultaneouslyand, therefore, it is a promisingway of measuringstructural intensity and power flow in arbitrarilycomplex structures under laboratoryconditions. Three differentlaser interferometricprobes are currentlybeing usedat GeorgiaTech for researchin structuralacoustics. The advantagesand disadvantagesof each systemwill be discussedwithin the contextof structuralintensity measurements.[Work supported by the Officeof NavalResearch, Code 332 SM.] 3347 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3347 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 2:15 3pSA4.Measurement of structuralintensity. GunnarRasmussen (G.R.A.S. Sound & Vibrationaps, Skelstedet 10B, 2950 Vedbaek,Denmark) Themodeling of structuralbehavior leads to simplifiedmodels of veryoften complex structures. To geta betterunderstanding of theenergy flow inside and out of thestructures, the development of measurementmethods is veryimportant. Dynamic movements are associatedwith vibratory and acoustic energy dissipation. If the surface area is largecompared to an acousticwavelength, acoustic intensityis a goodindicator of dynamicactivity. If thearea is smallcompared to a wavelengthat thefrequencies in question,surface measurementsusing the vibratory motion on thestructure surface may be a goodindicator. By transferof energybetween structural parts,point power measurements should be applied.Measurements may be carriedout usingacoustical techniques for determination of structureborne energy. The acoustical transducers used must be ableto measurecorrectly in veryreactive environments. A proper calibratedintensity probe will offera noncontactmeasurement of an area,which may be smallor largedepending on wavelengthfor measurementof vectors caused by dispersedwaves. The use of twoaccelerometers or an accelerometer and a forcetransducer may alsobe usefulfor detectionof energyflow in a structure.Acoustic calibration of intensityprobes has been improved to meetstandard requirements.Calibration of accelerometersand force transducers is carded out by substitutionmeasurements against a thirdtrans- ducer.Measurements on structureshas found many practical applications. ContributedPaper 2:40 2:55 3pSAS. Numerical investigation of error mechanisms in near-field 3pSA6. Energy partitioning in a truss structure. Kai-Ulrich acoustic holography (NAH). Gerard P. Carroll (Structural and Machensand Ira Dyer (Dept. of OceanEng., MIT, Cambridge,MA Hydroacoust.Res. Branch, CardcrockDivision, Naval SurfaceWarfare 02139) Ctr. (CDNSWC), Bethesda,MD 20084-5000) Near-fieldacoustic holography (NAH) hasbeen validated in precisely MIT is investigatingboth theoretically and experimentally wave propa- controlledlaboratory conditions for smallscale models. The practicalva- gationin trussstructures. Experiments were conducted to measureenergy lidity of the approachin nonlaboratorysettings for larger scalemodels, partitioningin flexural,longitudinal, and torsional vibrations of specific where increasedbackground noise, inexact sensor positioning, and other truss members. The truss consists of 109 aluminum struts assembled via 35 environmentalcontaminants are likely, needsto be established.In this jointsto form a regularstructure of 11 cellsconnected in series.A com- paper,the effectof theseerror mechanisms on the accuracyof cylindrical plete numericalanalysis [Y. P. Gut, I. Acoust.Soc. Am. 96, 3291(A) near-fieldacoustic holography are investigatednumerically. This is accom- plishedusing simulated holtgram plane pressure data obtained from sur- (1994)]finds that energy equilibria among different wave types can be face pressureand velocityresults. The surfacepressure and velocityare expected,the ratiosof which are dependentupon the distinctclasses of obtainedusing FEM/BEM calculations(SARA) for a ribbedcylindrical strutsmaking up the truss.This wastested by simultaneousmeasurement model.The simulatedholtgram plane data are obtainedfrom the SARA of the transferfunctions at variouslocations along the axisof eachstrut resultsusing a numericalimplementation (Gaussian quadrature) of the considered.The trusswas excited by broadbandwhite noise (5-kHz base- Helmholtzintegral. The errorsin the holographicreconstructions associ- band)at oneend of thetruss. Wave number processing extracts two com- atedwith background noise, sensor placement, and other error mechanisms plexwave amplitudes, each associated with traveling waves propagating in are revealedby comparingthe holographicallyreconstructed results with oppositedirections. Thus the spectralenergy content of the strutis known the originalSARA results.Since the ribbedcylindrical model under inves- and is comparedto othersin the sameclass. In addition,struts of other tigationis quitedetailed, this approach is a goodtest of theability of NAH to appropriatelyreproduce the complex surface behavior. [Work supported classesare measuredto discussissues related to equipartitionof energy, by ONR.] pass/stopbands and naturaldamping of complexbranched structures. 3348 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt.2, May1995 129thMeeting: Acoustical Society of America 3348 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp THURSDAY AFTERNOON, 1 JUNE 1995 GRAND BALLROOM SOUTH AND CENTRAL, 3:30 TO 5:30 P.M. Plenary Session,Business Meeting, and Awards Ceremony Jiri Tichy, Chair President,Acoustical Society of America BusinessMeeting Presentation of certificates to new Fellows Presentation of Awards R. BruceLindsay Award to BeverlyA. Wright Gold Medal to Kenneth N. Stevens DistinguishedSpeaker Gerald T. Garvey AssistantDirector, Physical Sciences and Engineering,Executive Office of the President, Officeof Scienceand Technology Policy, Washington, DC 20500 THURSDAY AFTERNOON, 1 JUNE 1995 GRAND BALLROOM SOUTH AND CENTRAL, 5:30 TO 6:30 P.M. Film Presentation The Caroling of Atoms: The life's work of Harvey Fletcher HarveyFletcher is both"The fatherof stereophonicsound" and the "fatherof psychoacoustics."He was the first one to showduring hisPh.D. work (with Robert Millikan) that the electron had a fixedquantized charge, and the first to accuratelymeasure the threshold of hearing.He providedT. A. Edisonwith a shoe-boxsized electronic hearing aid, manufactured by WesternElectric, and personally demonstratedstereo to A. G. Bell. He producedthe firstelectronic hearing aid, the firstelectronic (2-A) audiometer,discovered the criticalbands of thecochlea, and is wellknown for "thel:qetcher-Munson curves." This film presents some amazing footage from the 1950celebration of the 25thAnniversary of theAcoustical Society in New YorkCity thatmight bring tears to youreyes (54 mins, 16-mm color film). 3349 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3349 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp FRIDAY MORNING, 2 JUNE 1995 MEETING ROOM 16, 8:15 A.M. TO 12:15 P.M. Session 4aAA ArchitecturalAcoustics: Orchestra Shell and StageAcoustics Design Peter D'Antonio, Chair RPG DiffusorSystems, Inc., 651-C CommerceDrive, UpperMarlboro, Maryland 20772 Chair's Introduction---8:15 Invited Papers 8:20 4aAA1. An introduction to performance enclosure acoustics. Dennis A. Paoletti (Paoletti Associates,Inc., 40 Gold St., San Francisco,CA 94133) This paperwill providean introductionand overview of the acousticalparameters typically established by acousticalconsultants in thedesign of "enclosures"surrounding musicians performing on stagein theaters,concert halls, and multipurpose auditoria. A broad view of enclosuredesign must include facility design, musical instrument acoustics, engineering, theater consulting, and architectural design.Size, shape, configuration, and materials selection are all importantre: theacoustical performance of theenclosure. However, storagefor enclosurecomponents, structural considerations (in theengineering design of theenclosure, as well asthe engineering of the stage/backstagearea that will housethe enclosure),and operational and maintenance characteristics must also be considered.As complexas all of theseissues are to balance during the design of a performingarts complex, not to mentionbudget, the success of the enclosureis ultimatelyin thehands, and ears, of theperforming musicians, which leads to furtherconsiderations involving psychoa- coustics,visual aesthetics, fables, environmental conditions, and even potential conditions surrounding a performance faculty and its performingarts organizations. 8:40 4aAA2. Measured effectsof orchestrashells. J. S. Bradley (IRC, Natl. Res. Council,Montreal Rd., Ottawa,ON K1A 0R6, Canada) Theeffects of addingorchestra shells or modifyingorchestra shells were measured in sixdifferent concert halls varying in volume from3000 to 32000 m 3. Early, late, and total sound levels were seen to increasewith the addition of anorchestra shell. Effective orchestrashells were found to increasetotal sound levels by upto 2 dB at mid-frequenciesin audience areas of halls.Average changes to measuredclarity could be larger.The measuredincreases in soundlevels varied with locationin the hails,and in severalcases sound levelincreases were greatest towards the rear of halls.In onecase, adding an orchestrashell was found to decreaselow-frequency levelsdue to a shiftof theseat dip attenuation. On-stage, larger effects were measured. Support values increased by asmuch as 5 dB withthe addition of anorchestra shell. Partial changes to shellsgenerally produced much smaller effects. In audienceseating areas the effectsof partialchanges and adjustmentsto orchestrashells were usuallyless than estimated just noticeabledifferences in the measuredquantities. 9:00 4aAA3.Stage house coupled shells. Christopher Jaffe (JaffeHolden Acarbrough Acoustics, Inc., 114 A WashingtonSt., Norwalk, CT 06854) In the early sixties,the AmericanSymphony Orchestra League conducted a surveyof Americanorchestras to determinetheir preferenceof material for demountable symphonic enclosures. Oddly enough, Fiberglass reinforced polyester shells manufactured by StagecraftCorporation received the numberone ratingin the country.The Stagecraftshells, constructed of 0.0625- to 0.125-in. Fiberglasssheet, and edge framed in aluminum,were coupled to stagehouse volumes through openings between the ceiling sections. In the low frequenciessome coupling was achievedthrough the panelsthemselves, in view of their low transmissionloss at the bottom endof the spectrum.This paperwill documentthe successof theseenclosures, and explain why theseshells worked so well for orchestrasperforming in thesixties and seventies. Basic changes in multi-usetheater design in theeighties reduced the effectiveness of thesedesigns. However, several practitioners have developed new design solutions that have returned stage house coupled shells to the forefrontonce again. 4aAA4.Stage acoustics measurements with majororchestras. Dana Kirkegaard (Kirkegaard Acoustics, 4927 Wallbank Ave., DownersGrove, IL 60515) Thispaper will addressobjective and subjective measures relating to theauthor's work onstage with major orchestras. Based on thisresearch, some of thedesign challenges and potential solutions, including the use of QRDs,will be diagrammed. A formal paper will be available for distribution. 3350 J. Acoust.Soc. Am., Vol. 97, No.5, Pt.2, May1995 129thMeeting: Acoustical Society of America 3350 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 9:40 4aAA5.Active and passive orchestra shells and stage acoustics. W.C.J.M. Pdnssenand B. H. M. Kok (S•,stemfor Im9ro'•e6 AcousticPerformance, B. V. Uden,The Netherlands) Thisspring thelargest theater building t•[The Netherlands, theChasse Theatre atBreda, wascompleted. Ofthe two main auditoria, whichhave similar stage houses, one has electronic variable acoustics by meansof a SIAPsystem, including a stage system, and the otherhas mechanical variable acoustics which includes a largeorchestra shell. It will be shownthrough measurements that active (electronic)stage acoustics can be at leastas effective as passive (physical) stage acoustics. It is particularlyinteresting that loudness, reverberationtime, and reflection patterns can be influenced independently with active systems. This flexibility is an advantagefor meetingthe needs of performers.Furthermore, active control of stageacoustics can also provide a significantlyimproved foldback to actorsand singers for drama, opera performance, etc. when technical stage facilities and scenery make physical acoustic means difficult to apply.Since acoustic coupling of thestage to theauditorium main volume is animportant factor, results will alsobe presented of theachievements of the SIAP system to correctauditoria which have spaces with (extremely) poor acoustic coupling such as balcony andunder balcony areas. The orchestra pits, which are of differentsize and shape, but have the same passive acoustic treatment, will be compared. 10:00-10:10 Break 10:10 4aAA6. Adaptable acousticalshells incorporating modular reflective,absorptive, and diffusivesurfaces. Peter D'Antonio (RPGDiffusor Systems, Inc., 651-C Commerce Dr., UpperMarlboro, MD 20772) Theoptimum percentage and orientation of reflectingand diffusing surfaces in anacoustical shell was determined from objective andsubjective measurements using conservatory students at theCleveland Institute of Musiccomprising two string quartets, a brass quintet,and a hornduo. Objective impulse measurements were made with balloon bursts and five different microphone systems were usedto obtain simultaneous DAT recordings. The Head Acoustics mannequin was placed within the group to determine ensemble blend withoutself-masking. Etymotic Research probe microphones were inserted into the ear canals of musiciansto determineensemble blendwith self-masking, headband microphones were used to monitorensemble blend with self-masking, anomnidirectional micro- phonewas placed within the group as a monophoniccontrol, and spaced omnidirectional microphones were placed in thefront of the houseto measurethe projected sound quality. Analysis of theseand other data led to thedevelopment of a variableacoustics modular performanceshell utilizing reflecting, absorbing, and/or diffusing modules, which allows both variability and flexibility for different stageuses as well as sectional and personal acoustic environments for theperformers. This approach was subjectively evaluated with thefull BaltimoreSymphony Orchestra with David Zinman conducting. ContributedPapers 10:30 10:45 4aAA7.Supplemental partial height concert shell incorporating 4aAAS. Orchestra shell designand manufacture:The Wenger way. quadratic diffusor panels. Dana S. Hougland (David L. Adams RonProbst and Todd Benjamin (WengetCorp., 555 ParkDr., Owatonna, Associates,Inc., 1701 BoulderSt., Denver, CO 8021 I) MN 55060) Weng•rCorporation hasmanufactured orchestra shells for educational A recentlycompleted project to modify the acousticalperformance of and professionalspaces for over 30 years.This paperwill presentthe Boettcher Concert Hall included the addition of several modifications to designphilosophy behind the Wenget line of acousticshells. Pros and cons improvecross-stage hearing of the musicians.Boettcher Concert Hall uti- of standardizedequipment versus custom design and manufacturewill be lizesan in-the-roundseating arrangement, therefore, the enclosure design discussed/Also,the methodologybehind the designand developmentof wasrestricted to partialheight. Custom designed quadratic diffusors were the Diva AcousticShell and many of its innovativefeatures will be exam- ined. incorporatedinto the concert shell design. Tests were conducted both on an individualpanel section in an anechoicchamber and in situ.The resultsof 11:00-12:15 the testsare presented. PANEL DISCUSSION: TechnicalAspects of Products 3351 d. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3351 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp FRIDAY MORNING, 2 JUNE 1995 MEETING ROOM 3, 8:30 A.M. TO 12:00 NOON Session 4aAB AnimalBioacoustics: Passive Acoustic Tracking of Animals:Methods and ApPliCations Khosrow Lashkeri, Chair MBARI, 160 CentralAvenue, Monterey, California 93950 Chair's Introduction---8:30 Invited Papers •" 8:35 4aAB1. Effectsof low-frequencysound (ATOC) on marine mammals:An experimentalapproach. DanielP. Costa,Dawn Goley,Danielle Waples, Don Croll, BurneyLe Boeuf (Univ. of California--SantaCruz), JohnCalambokidus Cascadia (Research Collective),and JamesHarvey (MossLanding Maxine Laboratory) This presentationwill outlinethe researchprogram currently in placeto studythe effectof the CaliforniaATOC experimenton marinemammals. There are three phases to thisresearch: (1) a preliminarybaseline data collection period prior to anyATOC transmissions,(2) a pilot study(when ATOC transmissions would be manipulatedto assesseffects on mahnemammals), and (3) a monitohngperiod (when transmissions are optimizedfor climatestudy, ATOC feasibility operations). During the pilot study ATOC transmissionswould be 4 dayson, 7 daysoff andchanges in theanimals distribution, abundance, and general behavior measured. This experimentalpattern would be replicatedto providestatistical power. Although the objectives are different for eachperiod, the research methodologyremains the same. Methods used will be aerialand shipboard surveys to assessdistribution and abundance, shipboard observationsto assess behavior, a towedarray to assessacoustic behavior, photo-identification to examine long-term movements and stockidentity, and very kigh frequency (VHF) radio tags and time depth recorders (TDR) to assess dive behavior and movements. Data collectedduring the preliminary period are being used to predictsample sizes necessary for studiesthat would be carriedout during the pilot study. 9:00 4aAB2. Constraints on the sound production mechanism of blue whales. David S. Clark (Naval Command,Control and Ocean SurveillanceCtr., RDT&E Div. 721, SanDiego, CA 92152-5000),Mark A. McDonald,John A. Hildebrand,and Spahr C. Webb (ScrippsInst. of Oceanogr.,UCSD, La Jolla,CA 92093-0205) Broadband,high-fidelity recordings of bluewhale calls are used to modelparameters of thesound generation mechanism. Arrays of sonobuoyshave been used to characterizeand localize calling whales, providing broadband (10-2400 Hz), highdynamic range (90 dB)recordings. Blue whales typically produce 15- to 20-Hzsounds of upto 30-sduration at levelsof 185dB re: I /•Pa@l m.The observedsound levels, frequencies, and harmonic content have implications for the sound generation parameters. Source levels provide constraintson volumedisplacements. Frequencies and harmoniccontent relate to resonantstructures and theirmeans of excitation.The datashow harmonic series with selected overtones emphasized. The relative amplitudes of theovertones vary between different parts of the call. 9:25 4aAB3.Acoustic tracking of whalesusing hydrophone arrays: Implications for behavioralstudies and populationestimates. ChristopherW. Clark (CornellLab. of Ornithol.,Bioacoust. Res. Program, 159 Sapsucker Woods Rd., Ithaca, NY 14850) Understandinghow free-ranging whales use sound to communicate,navigate, and find food has been seriously hampered by the inabilityto consistentlyidentify, locate, and track the animal producing the sound. Only in themost tractable situations (e.g., coastal species,shallow water, breeding/calving season) has it beenpossible todescribe acoustic repertoires and prescribe biological functions. Thepotential use of suchacoustic techniques, in combination with traditional visual observation methods, for populationcensus efforts hasbeen clearly demonstrated in the case of bowheadwhales. Recent application of largeaperture arrays and beamforming techniques hasdemonstrated the feasibilityof usingsuch systems for locatingand tracking vocally active pelagic species. There is everyreason to believethat a combinationof acoustictracking and visual observation techniques can be successfullyextended for useas a census toolto producemeaningful estimates about relative abundance on blue, finback, and minke whales. Passive acoustic tracking methods, (towedarrays and fixed horizontal arrays) have now been successfully applied to follow individually vocalizing whales for many days, acousticallyobserve herds of animals,and describespecies specific seasonal changes in distributionand relativeabundance. 9:50 4aAB4.Localization of animalcalls via hyperbolic methods. Steve Mitchell and John Bower (Bioacoust. Res. Program, Cornell Univ., 159 SapsuckerWoods Rd., Ithaca,NY 14850) Forover a decadethe Cornell Bioacoustics Research Program has been using passive sparse acoustic arrays to locate calling marine mammalsin thenear field in shallowwater, as well as birds and other animals in air.The techniques used have been cross correlation followedby all-pairshyperbolic geometric positioning, using the simplest propagation model, and iterative nonlinear least-squares 3352 J.Acoust. Soc. Am., Vol. 97, No. 5, Pt.2, May1995 129thMeeting: AcouStical Society ofAmerica 3352 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp error minimization.This talk describessome of our experienceswith this process,including the resultsof calibratedfield tests. Applicationsto whalepopulation censusing and researchinto the countersingingbehavior of songsparrows will be discussed.Many bioacousficpassive array experiments depend on accuratelocations at the extremesof the nearfield, whererange is difficultto determine.Analysis techniques for passivenear-field arrays have appeared in the literatureover the past50 years.Recently there has beenmuch work devotedto usingdetailed propagation modeling to improvethe accuracyof undersealocalization of marinevessels. It is arguedthat, in the caseof animalcalls, there are alsoaccuracy improvements to be hadfrom improvedsignal modeling. 10:15-10:30 Break ContributedPapers 10:30 11:00 4aAB5. Using combined acoustic tracking and visual observation 4aAB?. Three-dimensional localization of a blue whale using techniques to study humpback whales. Adam S. Frankel and broadband matched-field processing for range and depth, and ChristopherW. Clark (CornellBiacoust. Res. Program,159 Sapsucker plane-wave adaptive beamforming for azimuth. G. L. D'Spain, W. Woods Rd., Ithaca, NY 14850) A. Kuperman,W. S. Hodgkiss,and L. E Berger (MarinePhys. Lab., ScrippsInst. of Oceanogr..San Diego, CA 92152-6400) The techniqueof acousticlocation was combinedwith visualtracking and behavioralobservation to studyhumpback whales on the winter mat- During a recentshallow water experiment conducted 10-15 km west ing groundsin Hawaii. The behaviorand movementsof nonvocalizing of San Diego, blue whale calls were recordedsimultaneously on two un- whalesand singerscould be studiedsimultaneously. Social interactions derwater hydrophonearrays, an 18-element,205-m-aperture horizontal that had not been previouslydescribed were observed.These included line array,and a 64-element,115-m-aperture vertical line array.These data affiliationsof singersand nonsingerswhile the singercontinued to sing. are used to localize the calling whale in 3-D space and then to make Visual trackingalso allowed the comparisonof visual and acousticloca- estimatesof its sourcelevel. First, adaptiveplane-wave beamforming is tions to verify the accuracy of the acoustic locations.Acoustic location usedwith the horizontalline array data to obtain finely resolvedbearing allowed the simultaneoustracking of severalhumpback singers, and their estimates.Then, the bottombathymetry profiles along thesebearing esti- relative distribution and orientations were examined. Results indicate that matesare used as input to a 2-D full-wave-fieldnormal mode code (written songmediates inter-singer separation and that 4 km was the preferred minimumspacing between singers off Hawaii. Humpbackshave been de- by Mike Porter)for generating"replica vectors" (i.e., predictionsof the scribedas being distributedwithin the 100 fathomcontour while on the acousticfield) receivedby the verticalline array.A searchin rangeand matinggrounds. However, singers were acoustically located up to 13 km depthfor the bestmatch between the replicavectors and the actualfield offshorein water as deep at 305 fathoms.While singersare typically measuredby the verticalarray ("matched-fieldprocessing") then is per- describedas stationap/,combined tracking techniques'revealed singer formedto obtainthe best-fitposition of the whale in 3-D space.Finally, speedsof up to 3.6 km/h. In conclusion.the combinationof acousticand estimatesof thesource level of thewhale calls are made. [Work partially visualtracking provided a morecomprehensive view of humpbackwhale supportedby ONR, Code321.] behaviorand distributionthan either techniqueseparately. 11:15 10:45 4aAB8. Simultaneous source pangtrig and bottom geoacoustlc 4aAB6. The use of passive towed arrays for surveying marine inversion using shallow water, broadband dispersion of fin whale mammals. JeffreyNorris, William Evans,Troy Sparks (TexasA&M calls. G. L. D'Spain,W. A. Kuperman(Marine Phys. Lab., Scripps Inst. Univ., P.O. Box 675, Galveston,TX 77553), and RobertBenson (Texas of Oceanogr.,San Diego, CA 92152-6400), C. W. Clark, and D. K. A&M Univ., CollegeStation, TX 77843-3367) Mellinger (CornellUniv., Ithaca,NY 14850) The first marine mammalacoustic survey using a towed passivehy- Beamformed time series of fin whale calls from the North Atlantic drophonearray was recentlycompleted. Other cetacean surveys have used recentlyhave been obtained.Spectrograms of theserecordings have an static,low-frequency arrays; the array used is a broadband,mobile system, unusualappearance--three to four downsweepingclicks occurin rapid receivingboth baleenand toothedwhale signals. For acousticcensusing succession,almost as if the whale was stuttering.These arrivalscan be andtracking (ACT) to becomean acceptedtechnique, it's biasesand as- explainedin termsof thedifferences in groupvelocity between the lowest- sumptionsmust be described.ACT hasa numberof advantages,including ordermodes that propagate in theshallow water (about 350 m) waveguide. a permanentrecord of all effort, comparedto visualmethods which are By matchingpredicted spectrograms calculated from a shallowwater instantaneoussamples, with no permanentrecord. This recordpermits waveguidemodel with actualspectrograms, estimates of boththe rangeof measurementof perceptionand availabilitybiases. A dynamicstrip width canbe calculated bycontinuously recording SPL. An area of 154621 km 2 the whaleand the compressionalwave velocityin the oceanbottom are obtained.The approachmakes variousassumptions, including that the was surveyedin the northcentral Gulf of Mexico duringseven cruises, recording1431 tapes.Recording effort occurredover 11 997 km of a total whale emitsa signalwith a downsweeprate of 25 Hz per second.How- transectdistance of 12 580 km, correspondingto a 95.4% level of effort;a ever,known deviations from the assumptions canbe incorporated into the concurrentvisual survey yielded a 48.5% level of effort. A total of 157 modeling.The resultshave several implications such as that whalesignals contacts from 13 cetaccan species wcrc recorded. including 67 sperm may provide loud, broadband,tomographle •ouree• of opportunityfor de- whale(Physeter macrocephalus), 22 pantropicalspotted dolphin (Stenella terminingoceanographic/geophysical properties, and that some differences anenuata),one baleen whale, 327 unidentifieddolphin, and 30 unidentified in whale call recordingsfrom differentpopulations of the samespecies cetacean contacts. Three-dimensional distributions were determined for may be causedby propagationeffects. Might whalestake advantageof spermwhale and pantropical spotted dolphin. Estimates of cetaceanpopu- propagation-induceddistortions in order to learn somethingabout the lationswere computed based on thiseffort. oceanmedium? [Work partially supported by ONR.] 3353 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3353 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 11:30 11:45 4nAB9. The MAP tag: A new marine mammal tracking system. 4aABI0. The study of aconstie interactions of territorial song CyrusBazeghi (Dept. of Cornput.Eng., Llniv.of California,Santa Cruz, sparrows,Melospiza reelodin, using passiveacoustic tracking. John CA 95064) and Guy W. Oliver (Univ. of California,Santa Cruz, CA L. Bower (Bioacoust.Res. Program,Cornell Lab. of Ornithol., 159 95064) SapsuckerWoods Rd., Ithaca,NY 14850) Developmentof the moven•nt and position (MAP) tracking system was motivatedby limitationsof currentlyavailable tags for marinemam- A passivesparse acoustic array of eight microphoneswas usedto mals.The MAP tagemploys a globalpositioning system (GPS) receiver to characterizethe patternsof acousticinteractions of territorialsong spar- accuratelyfix an animal'sposition when it surfacesand a tri-axialmagne- rows.The rectangulararray was placed in a four hectareopen field (near tometerand velocity-time4epthrecorder to trackin threedimensions un- Ithaca,New York) thatcontained 11 songsparrow territories. Recordings derwatermovements between surfacings. The tag is microprocessorcon- were madeapproximately every 3 daysfrom early April, when male song trolledallowing flexibility and user control of samplingregimes. Data are storedin a highcapacity datalogger. To minimizethe energybudget the sparrows0axived back from tl•eir wintering grounds, through July, when GPS receiveris only switchedon whenthe animalnears the surfaceand thebreeding season ended. Co..mputer analysis offield recordings showed switchedoff when a fix is obtained.The unit is battery-powered,self- that the arraywas ableto capturevocalizations of all I 1 territorialmales in containedand capable of deploymenton animalsdescending to 1500 m. thefield, and that these vocalizing males could be accurately located. Dam By attachinga pingerto the animalit can alsobe trackedacoustically, weretaken during three critical periods of thebreeding season: (!) territory allowingcalibration of passiveacoustic tracking systems. In its current establishment,(2) settlementof territoriesby females,and (3) nesting.For configuration,the MAP tag is designedfor deploymenton elephantseals, eachperiod, the timing of song,inter-song intervals, and song-typematch- but with relatively minor re.configuration of the packageit could be ing were discernedfor males. Patternsof acousticinteractions recorded ployedon manylarge rnarine vertebrates. It is anticipatedthat the capa- duringperiods of visuallyobserved male-male conflict were also investi- bility of theMAP tagwill dramaticallyenhance future studies of marine gated.These patterns were usedto evaluateseveral hypotheses that seekto mammalbehavior, navigation, orientation, and foraging. [Work supported explainthe functionof acousticinteractions in songsparrows. by ONR.] FRIDAY MORNING, 2 JUNE 1995 AUDITORIUM, 8:55 TO 11:30 A.M. Session 4aMU Musical Acoustics: Guitar Acoustics/Performance Uw.e J. Hansen, Chair Departmentof Physics,Indiana State University,Terre Haute, Indiana 47809 Chair's lntroduction---8:S5 •nvitedPapers 9:00 4aMU1, Acousticsof guitars. ThomasD. Rossing(Phys. Dept., Northern Illinois Univ., DeKalb, IL 60115) The guitarcan be consideredto be a systemof coupledoscillators. The pluckedstrings excite the top plate,which in turn transmits vibrationalenergy to the air cavity and back plate. Soundis radiatedquite effectivelyby the vibratingplates and throughthe sound hole.The considerableamount of researchon the guitarduring the past20 years,especially as it reflectson furtherdevelopment of this popularinstrument, will be reviewed. 4aMU2. Acousticaldesign criteria for the guitar. BernardE. Richardson(Dept. of Phys.and Astron., Univ. of WalesCollege of Cardiff, P.O. Box 913, Cardiff CF2 3YB, UK) The acousticalfunction of the guitar is now reasonablywell understood.The variousmodes of the vibratingstring couple to structuraland air-cavitymodes of the body.These in turninteract with the surroundingair thusenhancing the radiationof energyfrom the stringto the listener.The modalproperties of the instrumentare thus of centralimportance in determiningits soundquality. It is of greatinterest to themaker to knowhow these modal properties might be adjusted to produceinstruments of pre determined sound quality.This paperwill give a resumeof experimentaland theoretical work undertaken at Cardiffto determineformal relationships betweenphysical propexties of theinstrument (construction and materials) and psychoacoustical evaluation of guitartones. The aim of thiswork is notto'define parameters of an idealized"perfect" instrument--that would be a futilegoal. Instead, the aim is to identify thosefeatures of constructionwhich have a perceptibleeffect on theguitar's sound and to defineacceptable limits for modalproperties. The latter will be discussedtheoretically, but tapeddemonstrations will be presentedto emphasizethe pointsbeing made. 3354 d.Acoust. Soc. Am., Vol. 97, No. 5, Pt. •, May1995 129thMeeting: Acoustical Society ofAmedca 3354 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp lO:0O 4aMU3.The guitar:Air modesand radiated sound fields. IngolfBork, Ulrich Heise (Physikalisch-TechnischeBundesanst•t, Braunschweig,Germany), and UweJ. Hansen(Indiana State Univ., Terre Haute, IN 47809) Theexperimental technique of modalanalysis is generallyused to displaynormal modes of structuralvibrations. It provides a phasesensitive method of representinga slow motion animated display of thestanding waves supported bythe structure. The technique alsoallows exaggerated displacement representation on the computer screen for easeof observation.An essentialelement in the techniqueis associatedwith its ability to retainspatial phase information for a predeterminedgeometrical point distribution on the structurein relationto thepoint of excitation.The workdiscussed in thispaper utilizes this ability to retainphase information and extendsthe technique to represent the radiated sound field. The grid of observationpoints is removed from the structure and is replaced by a gridcovering the space where the sound field is to be modeled.The excitationpoint is retainedon thestructure. This will be illustratedby observingair resonancesin a guitarin computeranimation, and by representingthe radiatedsound field of thatguitar at variousfrequencies. 10:30 4aMU4. Designingand testingof new guitarsby criteria of appliedphysics and psychoacoustics.Michael Kasha (Ctr.for MusicRes. and Inst. of MolecularBiophys., Florida State Univ., Tallahassee, FL 32306-3015) Thisprogram represents the interaction of theauthors as designer of newguitars, with skilled luthiers as developers, and musicians asevaluators. The ultimategoal is thedevelopment of thefull brillianceand power which the instrumentshould be capableof, using modelsderived from the elementary laws of vibrationmechanics. The aim is to enhancethe response of thefour-octave range of the classicalsix-string guitar by introducingstructural asymmetry, borrowing the principle inherent in theviolin family of instruments.As a guide,the standardformulation of the boundaryconditions, and the frequencydependence of mechanicalimpedance, are incorporated--allthis within the construction limitations imposed by theluthier, the materials, and the aesthetics of theinstrument. The Backhanscriterion of brillianceis adopted,wherein the harmonic spectral intensity distribution is targetedin whichthe fundamental is dominant,and with decreasingintensity of higherharmonics. A speciallydesigned anechoic chamber has been constructed for testingreal-time harmonic spectra of stringinstrument pairs: conventional versus new designs (taking into account variations of player technique).Measurements will be madeto comparewith the Backhauscriterion. Ultimately, the judgement of musiciansand of the generalspectrum of musicalauditors will decidethe successof this program. 11:00 4aMU5. Adaptingintuitive ideas and appliedmechanics to the improvementof guitar acoustics:The luthier's view. ThomasHumphrey, Richard Schneider, and Michael Kasha (Ctr.for Music Res. and Inst. of MolecularBiophys., Florida State Univ., Tallahassee,FL 32306-3015) The mechanicalstructure of theguitar underwent a suddentransformation about 150 years ago in thehands of Antoniode Torres Jurado,under the demand on the part of JulianArcas, a virtuosoguitar performer of theday, for greater acoustical power and brilliance in theguitar. The Torres design features three revolutionary changes, (a) thetransverse structural bars of theexisting Mediterranean instrumentwere replaced by longitudinalfunctional bars, coupling the bridge action to thesoundboard, (b)the body dimensions were greatlyincreased, lowering the body and cavity resonance frequencies, (c) thestring length was greatly increased, leading to higher stringtension requirements, thereby further increasing acoustical power. Each luthier will presenthis approach to understandingthe mechanicalaction of thetorres design, and its modificationsfor theacoustical requirements of modernmusical performances. The presentationwill be followedby live demonstrationsof various guitars by musicians. 3355 d. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3355 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp FRIDAY MORNING, 2 JUNE 1995 MEETING ROOM 2, 11:00 A.M. TO 12:00 NOON Session 4aNS Noise: ProgressReport and Discussionon the Continuing Activity of ASA's Role in Noise and Its Control Robert M. Hoover, Chair Hoover and Keith, Inc., 11381Meadowglen, Houston, Texas 77082 Invited Paper 4aNS1. Progressreport and discussionon the continuing activity on ASA's role in noise and its control. Robert H. Hoover (Hooverand Keith, Inc., 11381Meadowglen, Houston, TX 77082) A discussionmeeting is beingsponsored by the TechnicalCommittee on Noiseto review progressmade to dateon the actions initiatedat the Denver,1993 meetingto increasethe role of theASA in noiseand noisecontrol. Much of this actionevolved out of an all-dayworkshop held at the Ottawa,1993 ASA meeting.Members of the steeringcommittee and othersinvolved in related supportingactivity will review specificprogress made in the areasof education,increasing public awareness about noise and noise control,and encouraging joint activityin this areawith otherprofessional organizations. Included will be a reporton a trial presentation on acousticsand noise given to 6 high schoolclasses. Discussion about, and review of opportunitiesfor involvementwith, these activitieswill be encouraged. FRIDAY MORNING, 2 JUNE 1995 GRAND BALLROOM CENTRAL, 8:00 TO 11:45 A.M. Session 4aPP Psychologicaland PhysiologicalAcoustics: Harvey Fletcher Memorial SessionI 3ont B. Allen, Cochair AT&T Bell Laboratories,Room 2D-553, 600 MountainAvenue, P.O. Box 636, Murray Hill, New Jersey07974-0636 Mohan M. Sondhi, Cochair AT&T Bell Laboratories,Room 2D-553, 600 MountainAvenue, P.O. Box 636, Murray Hill, New Jersey07974-0636 Chair's Introductions8:00 Invited Papers 8:15 4aPPI. Harvey Fletcher:A son'sreflections. StephenHarvey Fletcher (3046 ComancheLn., Provo,UT 84604) HarveyFletcher was born on 11 September1884, in Provo,Utah, of pioneerparents. He receiveda B.S. degreefrom Brigham YoungUniversity. He thenentered the Universityof Chicago,where he workedwith RobertMillikan on the determinationof "e", and earnedhis Ph.D. in physics,summa cure laude, in 1911. He was madedirector of acousticalresearch at Bell Laboratoriesin 1928. and the following year. co-foundedthe AcousticalSociety of America.By 1935 he was made directorof physicalresearch at Bell Laboratories.As such,he supervisedthe work of ShockIcy,Bratrain, and Bardecnin the developmentof the transistor;Dean Wooldridge,James Fiske, Charles Towne, and many other outstanding physicists. Upon retirement from Bell Laboratories,Harvey Fletcheraccepted a positionas professor of electricalengineering at ColumbiaUniversity, a positionhe held for 3 years.In 1952,he returnedto BYU asdirector of research,and from 1960 until his death at theage of 96, heactively pursued the study of musicaltones. 3356 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3356 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 8:30 4aPP2.Harvey Fletcher: Friend and scientific critic. LeoL Beranek(975 Memorial Dr., Ste. 804, Cambridge, MA 02138-5755} HarveyFletcher was active in WorldWar II bothin theearly days of defenseresearch under the auspicies of theNational Defense ResearchCommittee and later as Chief of SectionI7.3 of the Office of ScientificResearch and Development.He was a memberof the National ResearchCouncil committeethat startedand oversawthe researchof the Electro-AcousticLaboratory at Harvard Universityof whichI wasnamed Director. Within a yearor soDr. Fletcher's OSRD Section 17.3 took over the supervision. In the latter partof WorldWar II, I wasnamed Director of theSystems Research Laboratory under the Office of FieldResearch. Dr. Fletcherwas appointedas one of a groupof fiveto overseethe activities of thisLaboratory. This paper is a collectionof anecdotesand remem- brancesof Fletcherin thefast-moving and important military research and development period from 1940until 1945when I reported oftento him.Personal contacts with him continuedafter the war, frequently at first,and sporadically for thenext three decades. "Uncle Harvey,"as I cameto call him, wasboth a friendlyguide and a demandingscientific critic. 9:00 4aPP3.Harvey Fletcher: Some personal recollections. CyrilM. Harris (Dept.ofElect. Eng. and Graduate School ofArchitecture, ColumbiaUniv., New York, NY 10027) The authorof thispaper describes his firstvisit with HarveyFletcher in 1940at theAcoustical Research Department of Bell TelephoneLaboratories, then located on WestStreet in New YorkCity. Five yearslater, he wasinvited by Dr. Fletcherto join the Laboratories.A brief description is givenof someof thework carried out in AcousticalResearch at thattime. Upon his mandatory retirementat age65, "UncleHarvey" accepted the positionof VisitingProfessor in the Departmentof ElectricalEngineering at ColumbiaUniversity. In 1951the author left Bell Labsfor a teachingposition in Europe;on hisreturn to theU.S. a yearand a half later,he again sought Dr. Fletcber'scounsel and it wassuggested he take Fletcher's place at ColumbiaUniversity. This made it possible for Dr. Fletcherto returnto Utah, wherehe devotedthe restof his distinguishedcareer to researchin musicalacoustics at Brigham YoungUniversity. 9:15 4aPP4.Harvey Fletcherand auditory theory. NelsonYuan-sheng Kiang (MIT, HarvardMedical School, Massachusetts Eye and Ear Infirmary,243 CharlesSt., Boston,MA 02114,and Massachusetts General Hospital) HarveyFletcher was an originalthinker whose career is worthexamining for futurescientists. Trained as a physicist,he developed a pragmaticapproach to psychophysicsthat virtually defined the engineeringapproach to acousticcommunication. Although his practicalachievements were considerable, he alsotried to integrateall thatwas known about hearing in the 1953version of his "space-timepattern theory of hearing."It is instructiveto comparethat formulation with the ideas of todayafter more than four decadesof intenseresearch. Many of the issuesthat concerned Fletcher have been resolved; many others remain uncertain. For example,the observation that low-frequency stimuli can mask high-frequency stimuli whereas high-frequency stimuli cannot mask low-frequencystimuli was accorded great significance by Fletcher.It is nowknown that a keyfactor lies in theasymmetry of tuning curvesfor basaland apical turn auditory-nerve fibers. On theother hand, the full implicationsof thesephenomena, especially for centralprocessing mechanisms, isvirtually unexplored. What is clear is thata majoreffort to producea unified theoretical framework for researchin hearingis longoverdue and a modernFletcher would be welcometoday. 9:30 4aPPS.Fletcher and pitch. 1ohnR. Pierce (Dept.of Music,Stanford Univ., Stanford, CA 94305) Preparingremarks on Fletcber's work on pitch changed drastically. My viewof thedevelopment of our present understanding. In 1940Jan Schouten showed that canceling out of thefundamental of a pitchedtone did not change pitch. Schouten called the surviving pitchresidue pitch. This inspired a spate of papersby peopleignorant of earlierwork. I hadknown Fletcher [Phys. Rev. 23(3), 427-437 (1924)]had shown that filtering out the fundamental and lower harmonics of a varietyof musicalsounds did not change the pitch,and, through synthetic sounds, that mere equal frequency spacing of tonesdid not give a pitchequal to thespacing. Thus, the pitchheard was evoked by harmonicpartials. Unhappily, Fletcher proposed an unsound explanation in terms of productionof the fundamentalin the ear by nonlinearities.In a latterreport, Fletcher [J. Acoust. Soc. Am. 1, 3II-343 (1930)]gave an incomplete analysisof thefunctioning of the cochlea. Among his valid conclusions hesaid "the pitch of a toneis determined both by the position of its maximumstimulation on the basilarmembrane and also by the timepattern sent to thebrain. The formeris probablymore importantfor high tones and the latter for low tones." That is our present understanding. Fletcher [J. Acoust. Soc. Am. 23, 637-645 (I951)] subsequentlygave a "correct"analysis of thefunctions of thecochlea, agreeing with the experimental work of vonBekesy, andgoing a littlebeyond papers a yearearlier by Petersonand Bogert and by Zwislocki. 9:45 4aPP6.From Fletcher to Knudsen.Harry Levitt (Ctr.for Res. in Speechand Hear. Sci., City Univ. of NewYork, Graduate School andUniversity Center. 33 W. 42ndSt., New York.NY 10036) HarveyFletcher was not only an outstanding researcher and director of oneof theworld's leading research laboratories, butwas alsoan inspiring teacher and mentor. Vern Knudsen was one of manyoutstanding researchers who were deeply influenced byFletcher. Knudsen'scontributions in architectural acoustics, psychoacoustics, audiomerry, hearing aids, and tactile stimulation were of ground- breakingimportance and reflected Fletcber's remarkable influence. As a closedisciple of Fletcher,Knudsen was also in a positionto learnabout many of Fletcber'sother accomplishments which were substantial, but unknown to theoutside world. 3357 d. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3357 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 10:00-10:15 Break 10:15 4aPP'/. Predictionof articulationscores. ChristineM. Rankovic (Dept.Speech-Language Pathol. and Audiok, Northeastern Univ., 360 HuntingtonAve., Boston,MA 02115) Harvey Fletcherdeveloped articulation theory to enablethe predictionof the speechtransmission capacity of imperfectcommu- nicationsystems, thereby eliminating the need for the time-consumingspeech recognition testing that is otherwiserequired to differentiateamong systems. Two assumptions underlie the theory: (1) a speechsignal in eachof a numberof contiguousfrequency bandscomprising the audiblespectrum contributes independently to the articulationscore (percent-correct for listsof nonsense syllables);and (2) theseparate contributions are additive. The approachof Fletcherand his colleagues was to definethe articulation index,A, anentity for whichthese assumptions hold true. The equationsfor calculatingA containvariables representing hearing acuity, criticalbandwidth, masking, loudness, perception, and frequencyimportance weights so that the communicationsystem's frequency responseand gain are translatedinto perceptualterms. In additionto the derivationof the theory,Fletcher's 1953 bookprovides a methodfor calculatingA usingcharts and tableddata, as well as an extensivevalidation study that includeda varietyof suboptimal systems.Fletcher's presentation of articulationtheory is far morecomprehensive than two popularversions [ANSI S3.5-1969;N. R. Frenchand ][. C. Steinberg,J. Acoust.Soc. Am. 19, 90-119 (1947)].Differences among these versions of theA calculationand consequencesfor predictingarticulation scores will be discussed.[Work supported by NIH.] 10:45 4aPP8. Speech recognitionat higher than normal speechand noise levels. Gerald A. Studebakerand Robert L. Sherheeoe (MemphisSpeech and Univ. of MemphisHear. Center, 807 JeffersonAve., Memphis, TN 38105) Onefinding of theearly investigator• at theBell Telephone Laboratories was that the articulation index (Al) decreasedwhen speech wasamplified above normal conversational levels (French and Steinberg, 1947; Fletcher and Gall, 1950).Recent efforts to predictthe performanceof heating-impairedsubjects using heating aids under real world conditionshas produceda renewedinterest in this phenomenon.A studywill be describedthat attemptsto quantifythe effectsof higherthan normalspeech and noiselevels. Data for normal-hearingsubjects revealed that raising the speechlevel from 65 to 100 dB SPLreduced the AI by about0.003 unitsper dB and thatthis slope remained fairly constantfor S/N ratiosbetween -2 and +19 dB. Data on hearing-impairedsubjects are currently being collected.Results for bothsubject groups will be comparedwith thoseobtained by Fletcherand his colleagues. 11:00 4aPP9. Probabilitytheory and speechperception. ArthurBoothroyd (City Univ. of New York, 33 W. 42 St., New York, NY 10036) Fletcherrecognized the value of probabilitytheory in developinga quantitativeapproach to speechperception hencethe articulationindex (AI). He alsorecognized the needto allowfor violationsof theindependence assumptions that underly basic probabilitytheory. For example, in nonsensesyllables, the probability (p•,) of recognizinga word equals p•, wherepp is the probabilityof recognizing theconstituent phonemes andn isthe number of phoneroesperword. In realwords, however, pw=p•, wheren •>j•> 1. Similarly,extending the methodsof AI, the probabilityof recognitionof wordsin sentences(Sp•,) can be shownto berelated to the probability of recognition in isolation ('p •) bythe equation Sp•,__ 1- ( l - ip•)k, wherek isan exponent reflecting the contributionof the sentencecontext. From these two basicequations one can derive relationships among many measures of speech perception,ranging from the phoneticlevel to the sentencelevel. The empiricalvalues of the exponentsj andk can be usedboth to quantifythe effectsof variousstructural and contextualconstraints and to assessan individual'suse of thoseconstraints. [Work supportedby NIDCD GrantNo. 10078.] 11:15 4aPPI0. Harvey Fletcherand moderncompression hearing aids. EdgarVillchur (Foundationfor Hear.Aid Res.,P.O. Box 306, Woodstock,NY 12498) HarveyFletcher described the effectof a transmissionchannel on speechrecognition in termsof the channel's"articulation" plottedagainst channel gain. For normallisteners, articulation increases with gainto a maximumand then levels off or decreases.For hearing-impairedlisteners, however, Fletcher noted: "... thegain at, corresponding to the tolerable level is reachedbefore it is large enough(to bring articulation to a maximum)."This occurs in cochlearimpairment because the dynamic range of hearingis reduced byrecruitment. It is theproblem to whichthe design of moderncompression heating aids is addressed.Compression aids compensate for recruitmentby providingincreased relative •ain for weaksoeech sounds: thus they allow the articulationto reachhigher valne• beforetolerance levels are exceeded. An analysisof compression/equalizationsignal processing is presented.The essentialelements of thisprocessing are: (1) morethan one channel of full-dynamic-rangecompression (the K-AMP design achieves similar results in a differentway), (2) post-compressionfrequency-response shaping, and (3) adjustabilityof thecompression in each channel, and of theequalization, to fit theamplified speech into the residual dynamic and frequency range of heatingof theindividual patient. 3358 J.Acoust. Soc. Am., Vol. 97, No. 5, Pt.2, May1995 129thMeeting: Acoustical Society of America 3358 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp FRIDAY MORNING, 2 JUNE 1995 MEETING ROOMS 12, 13, 14, 8:15 A.M. TO 12:10 P.M. Session 4aSA Structural Acousticsand Vibration: Structure-BorneNoise Techniques JosephM. Cuschieri,Cochair Collegeof Engineering,Florida Atlantic University,Boca Raton,Florida 33431-0991 Gerard Carroll, Cochair CarderockDivision, Naval SurfaceWarfare Center, Bethesda, Maryland 20084-5000 Chair's [ntroduction--8:15 Invited Papers 8:25 4aSA1. Physicalparameters of a welded t-joint that impact structural acoustics. J. Adin Mann, HI, Mauhew Carney,and PatriciaDriesch (Aerosp.Eng. and Eng. Mech., 2019 BlackEng. Bldg., Iowa StateUniv., Ames, [A 50011} The influenceof weldedjoints on theaccuracy of analyticalstructural acoustic models is investigated.A beam with a T-shapedrib attachedto it is studied.Welding a t-jointcauses geometry variation, static stress, and material variations that are not currently included in computationalmodels of the strucluralacoustics of a t-joint.Two techniquesof processingthe experimental data are used to show thatthe geometry and the static stresses caused by weldingcan have a significantimpact on wavespropagating past the joint andthe resultingradiated sound power. Likewise experimental results show that the materialvariation caused by the weldingof thejoint has minimalimpact on the wavepropagation and sound radiation from the beam.The processingtechniques are a phase-speedtracking filterand wave-number filtering. The phase-speedtracking filter showsan increasein the phasespeed of propagatingwaves near the joint. There is alsoa reductionin the groupdelay of wavepackets propagating past the joint and a changein the reflectioncoefficient of structuralwaves incident on the joint. The wave-numberfiltering is usedto quantifythe amountof far-fieldsound radiation from thearea of the t-jointon the beam.Finally an analyticmodel that describes a rib as impartinga forceand moment on a beamin reaction to the incidentstructural waves is modifiedto includethe influenceof the weld fillet geometryand staticstress induced by welding. [Worksupported by ONR, Dr P.B.Abraham Scientific Officer.] 8:50 4aSA2.The responseand radiationof ribbedpanels, J. Dickeyand G. Maidanik (DavidTaylor Res. Ctr., Annapolis, MD 21402) The dynamicresponse of a panelwith an infinitenumber of regularlyspaced line impedances(i.e., regularlyribbed), or a finite numberwhich may be irregularlyspaced and nonidentical,is a systemwhich can be solved"exactly." Exact, that is, to withinthe approximationsemployed in developingthe equationsof motionfor the paneland the ribs.Even though these approximations may precluderealistic modeling in some(usually high) frequency ranges, or with someconfigurations (e.g., wide ribs), these canonical modelsexhibit many characteristics of experimentaland numerical data obtained on real andmore complete slructures. This makes them very usefuland costeffective in identifyingobserved characteristics and evaluatingnoise control measures. Models which describeflexural or longitudinalwaves on membranesor thinplates have been developed by theauthors. These models are reviewed andused to describethe response and radiation of a panelinto an adjacent fluid. The panel is driveneither by a linedrive parallel with theribs or an incidentplane wave. There are a hostof phenomenawhich manifest themselves; some of whichare: (1) passand stop bands,(2) localizationand de-localization, (3) aliasing,(4) freewave dispersion and the splitting of thedispersion curves due to fluid loading,(5) Braggdiffraction, and (6) radiationefficiency. Also presented is the effect on thesephenomena of: (I) alteringthe strict periodicityor identityof theribs, (2) theloss factor in thepanel, and (3) thedegree of fluidloading. 9:15 4aSA3. Cavity-backed simply supported plate for acoustic and structural responsemeasurements. Yvan Champoux,Serge Brunet,and Alain Berry (GAUS,Mech. Eng. Dept., Univ. de Sherbrooke,Sherbrooke, PQ J1K2RI, Canada) Originally,an acousticcavity has been designed and fabricated to studyactive noise control strategies in a closedvolume. It has a parallelepipedicshape of dimensions0.868 mx I. 15mx 1.0m withwalls made of 13-era-thickreinforced concrete. The top is closed witha simplysupported 6.63-mm-thick aluminum plate. The platesupport was carefully designed to meetthe simply supported boundaryconditions. The plate is excited by a point force and its structuralresponse ts measuredwith force and accelerometer transducers.The acousticfield insidethe cavity is alsomeasured using microphones. Comparisons between calculated and measured naturalfrequencies of theplate shows that for mostof the modesfound in the 0-500 Hz range,the discrepancyis lessthan 1 Hz. Quadraticmean surface velocity and mean volume sound pressure have been calculated from frequency response functions measured for centeredand off-centered point force excitations. Comparisons with calculatedvalues shows very goodagreement. The relative contributionof the variousplate modes and cavily modesare well distinguishable. 3359 J. Acoust.Soc. Am., VoL97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3359 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 9:40 4aSA4. Experiencepredicting structure-borne no'se within a prolotyperectangular acoustical enclosure. Robert1. Bernhard andNancy M. Franchek(1077 Herrick Labs., School of Mech.Eng., Purdue Univ., West Lafayette, IN 47907-1077) Approximately10 yearsago a largereetangniar enclosure was designedand constructedusing a steelsuper-structure and sand- filled,double-panel plywood walls. The enclosure is approximatelythe size of a transportationvehicle passenger cabin (1.85 m by 1.05 m by 1.05m). Theenclosure was built such that any of thewalls could be replaced with morerealistic structures such as vehicle panel constructions.The enclosurehas been modified many times to aceommodmevarious experimental apparatus. In thispaper, the design of theenclosure will be describedand some of theoriginal data used to verifyits characteristicswill be shown.Recently, the enclosure hasbeen modified to resemblestructure (0 describedby theStructure-borne Noise Committee of INCE-USA.One wall of thestructure hasbeen replaced by a simplysupported panel. Experimental results have been compared to analyticaland numerical predictions for bothinternal acoustic excitation and mechanicalexcitation of the panel.These results will be discussed.In addition,an effort hasbeen madeto designa smallversion of thisenclosure which could be usedfor roundrobin testing. Preliminary results of thiseffort will also be discussed. 10:05 4aSAS.The French benchmarkon computationalmethods and experimentsin structuralacoustics. C. Valor (Socitt6 Fran•aisedes M•caniciens (S.F.M.), Socitt6 Fran•aise d'Acoustique (S.F.A.). Paris, France) The ideaof creatinga workinggroup to performbenchmark on computationalmethods and experimentsin structuralacoustics originatedas a conclusionof the congress"Prediction of the noiseemitted by vibratingstructures," held in March 1991.This group was effectivelycreated in 1993, by S.F.M. and S.FoA.and is constitutedby researchersworking in laboratories,industries, and consultingcompanies. The nameof theparticipants with theiraffiliation will be givenat theoral presentation. In orderto simplifythe publicationsof thiswoxking group, a fictitiousname (C. Valor)has been created and represents the participants. Each year several one-daymeetings are organized,they are devotedto the comparisonof the differentresults obtained on each benchmarkcase. The discrepanciesare analyzed,leading to new calculationsif necessary.When a commonagreement is obtainedby the workinggroup, eachparticipant having performed the resultswrites a scientificreport collected by the workinggroup. The final goal is to publisha book giving the synthesisof all the work producedby the group. During the presentation,the computationaland experimental benchmarkwill be presentedand examplesof resultswill be discussed. 10:30-10:40 Break ContributedPapers 10:40 to a modifiedtheory of acoustoelasticity•o eta!., J. Appl. Mech.58, 11-17 (1991)].The theory allows the static stress components to be addi- 4uSA6. Power transmissionvariance predictionsin complexsystems tions to the elastictoodull of the body.The soundpower radiatedby a with dissipation.Jotm Burkhardt and Richard Weaver (Dept.of Theor. beam was calculated from the FEM model results for axial, transverse, andAppl. Mech., Univ. of Illinois, Urbana,IL 61801) shear,and combined distributions of the stresscomponents. Experimental The eigenstatistiesof dampedcomplex systems are examinedfor the resultsshowed that the soundpower increased by up to 1 dB as the static purposeof improvingstatistical response predictions such as thoseformu- stress was varied. Results from the FEM model showed that all the indi- latedin statisticalenergy analysis and statisticalroom acoustics. Both the vidual stresscomponents contribute to the radiationand the combined statisticaldistribution of modaldecay rates and the effect of dissipationon effectwas about a I dB increasein the radiatedpower. Both experimental the intermodalcorrelation of the naturalfrequencies described by the and modelresults suggest that staticstresses induced by discontinuities gaussianorthogonal ensemble (GOE) of randommatrix theory are ex- suchas welding and bolting can play a role in themechanisms of thesound plored.It is foundthat the modaldecay rates are distributed according to radiationat a discontinuityin a structure.[Work supported by ONR.] a chi-squaredistribution whose degree dependson the distributionof dampingin the systemand the wavelengthof the disturbance.The inter- modalcorrelations of the naturalfrequencies are foundto be unaffectedby the presenceof moderatedamping. Level repulsion(the absenceof near 11:10 degeneracies)and spectral rigidity (the near regularity of thespectrnm) are found to conformto the predictionof the GOE providedthe systemis 4aSAS. Effect of thickness variations on the sound radiation from reverberant.The varianceof thepower transmission function for an irregu- beams. Julie C. Slaughter,J. Adin Mann, l•I, and Daniel O Adams larly shapedmembrane is formulatedusing a GOE-typenatural frequency (Aerosp.Eng. and Eng. Mech., 2019 BlackEng. Bldg., Iowa StateUniv., spectrumand chi-squaredistributed modal decayrates. Numerical simu- Ames,IA 50011) lationsof membranesare performed which confirm the calculated effect of a distributionof decayrates on powertransmission characteristics. The effect that spatialthickness variations of a beamhas on the beam's far-field sound radiation was studied. The steel beams that were used in the initial testsshow that at low-frequencyranges (500-1500 Hz) the thick- 10:55 nessvariations acted as discontinuitiesalong the beam that increased 4uSA7. Influence of local static stress on structural acoustics: soundradiation. However, at higherfrequency ranges (2000-4000 Hz) the Experiment and modeling. Hareen K. Gangalaand J. Adin Mann, III thicknessvariations, when spaced at certainintervals, acted as globalstiff- (Aerosp.Eng. and Eng. Mech., 2019 BlackEng. Bldg., Iowa StateUniv., ness changesand decreasedthe sound radiation. This decreaseoccurred Ames, IA 50011) when the spacingof the variationscorresponded to a structuralwave- length.Composite beams with thicknessvariations have also been built An experimentalsetup was designed to locallyintroduce stresses in a andtested. The spatialthickness variations appear to havea similareffect steelbeam. The far-field sound power radiated by thebeam was experi- on the soundradiation as in the steelbeams. The two dataprocessing mentallycalculated for variousmagnitudes of the inducedstresses. As a techniquesused to evaluatethe influence of thespatial thickness variations model,a finiteelement code was developed for theequation of motiondue were a phase-speedtracking filter to quantifywave propagation in the 3360 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 12gthMeeting: Acoustical Society of America 3360 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp structureand a wave-numberdomain filter to quantifyfar-field radiation. clingwere used to understandthe contribution from the tire vibrations. The Resultsfrom these tests will be usedto helpdetermine how quieter mate- laboratorymeasurements of both vibrationand radiatednoise compare daiscan be designed. [Work supported by NSE] well with the estimatesfrom the analyticmodeling. Using an estimateof theinteraction force between the tire andthe grid, from the fieldvibration 11:25 data,it is shownthat the estimatedradiated noise level is comparableto the field measured noise level at the curb. This leads to the conclusion that the 4aSA9. Structural vibration noisefrom open grid bridge decks. I. noisefrom the tire vibrationsis the dominantsource, and mitigationpro- M. Cuschieri (Ctr. for Acoust.and Vib., Dept. of OceanEng., Florida ceduresmust consider ways of reducingthe excitationof the tire. This Atlantic Univ., Boca Raton, FL 33431) and M. Tournour (Sherbrooke conclusionis verifiedby soundlevel measurementsperformed with the Univ., Sherbrooke,Canada) contributionfrom the grid vibrationsremoved. [Work sponsoredby The contributionto the overalltonal component of the noisefrom the •OT.] vibrationof the grid sectionof an opengrid bridgedeck due to excitation by the interactionwith the vehicletires is investigated.Using vibration field measurementsof the grid and laboratorymeasurements of the acous- tic radiationefficiency, it is shownthat the contribution to the overallnoise levelmeasured at the curbfrom the vibrationsof the grid is insignificant. 11:55 The main reasonfor this resultis the pooracoustic radiation efficiency of the grid. Becauseof the largepercentage of openarea, the plate-likemodes 4aSAII. Combined large area sensor-•actuator tile for the of the grid deck have very poor radiationefficiency. Similarly, the indi- NRL-ABC platform. Robert D. Cotsare and Brian Houston (Naval vidualgrid elements,based on theirsize and the frequencyrange where the Res. Lab., Code 7130, Washington,DC 20375-5350) predominantexcitation from the tire takesplace, are alsovery inefficient acousticradiators. The significanceof this resultis that mitigationproce- A new researchplatform has been constructed for underwaterstudies duresthat only reducethe vibrationof the grid will not significantlyreduce of sensor/actuatorcoupling mechanisms. it consistsof a 15-tilearray of theoverall radiated noise. [Work sponsored by FDOT.] "ABC" tiles, whereeach tile containsa largearea actuator,pressure sen- sor,and velocitysensor, where the latteris constructedby summingand 11:40 integratingthe outputsof four accelerometers.This paperpresents details of the tile designand the predictive models used. Issues addressed include 4aSAI0.Tire noisefrom opengrid bridgedecks. J.M. Caschieri (Ctr. spatialsampling, near-field sensing, internal resonances, and bothdirect for Acoust.and Vib., Dept. of OceanEng., FloridaAtlantic Univ., Boca andextraneous coupling mechanisms, all of whichcan contribute to com- Raton,FL 33431)and S. Gregory (GeneralDynamics, Groton, CT) plicatethe systemtransfer functions. Acoustic characteristics of the ABC Having identifiedthat the contributionto the overall noisefrom the tile were evaluatedin the NRL LargePool Facility,both in the free field grid vibrationsis insignificant,the attentionis focusedon the noiseradi- and whenmounted on a backingstructure, and theseresults are compared ated from the vibrations of the tire. Field measurements of tire vibrations with predictions.Implications for localcontrol of the actuator'ssurface are are ratherdifficult, therefore laboratory measurements and analyticmeal- also discussed. FRIDAY MORNING, 2 JUNE 1995 CONGRESSIONAL HALL A, 8:30 A.M. TO 12:00 NOON Session 4aSC SpeechCommunication: Potpourri (Poster Session) Sandra Gordon-Salant,Chair Departmentof Hearingand SpeechSciences, University of Maryland,College Park, Maryland20742 ContributedPapers All posterswill beon displayfrom 8:30 a.m. to 12:00noon. To allowcontributors an opportunityto seeother postern, contributors of odd-numberedpapers will be at theirposters from 8:30 to 10:15a.m. and contributors of even-numberedpapers will be at theirposters from 10:15 a.m. to 12:00 noon.To allow for extendedviewing time, posterswill remainon displayuntil 8:00 p.m. 4aSCI. Lexical distinctivenessin lipreading: Effects of phonemie lexicalequivalence classes. For example,under the recedingrule that/b/ equivalenceclasses on the structureof the lexicon. EdwardT. Auer, andIpl arein thesame pbonemic equivalence class the words"bat" and Jr.and Lynne E. Bernstein(Ctr. for Auditoryand Speech Sci., Gallaudet "pat"map into the same lexical equivalence class. After applying a setof Univ.,800 Florida Ave. N.E., Washington, DC 20002) recedingrules to a largeonline lexical database, the resulting structure of the lexiconcan thenbe studiedquantitatively. One suchmeasure of the Speechperceived on the basisof viewinga talker'sface affords less recedingeffects on the lexicon is percentinformation extracted (PIE) [D. phoneticdistinctivehess than acoustic speech. Effects of thisreduced dis- tinctiveness can be estimated in relation to the structure of the mental M. Carter,Cornput. Speech Lang. 2, I-! I 0987)]. Lexicalstatistics de- lexicon.Based on empiricalmeasures of phoneticconfusability, receding scribingthe results of applyingsets of recedingrules derived from analy- rulescan be definedfor mappingfully specifiedphonelogical forms into sesof visual-phoneticconfusability to a 30 000-entrylexicon will be pre- 3361 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3361 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp sented.Implications for the use of top-downlexical constraintsin ample,"dentast" and "koibisk"could be presenteddichotically, with sub- resolvingbottom-up visual-phonetic ambiguity during lipreading will be jeers judging if "dentist" was presented.The migrationof the vowel, discussed.[Work supported by NIH.] leading to erroneousperception of a pre-specifiedtarget, occurredless often with word targetsthan with nonsenseword targets.This resultindi- 4aSC2. The effects of featural priming on word recognition. E. catethat the lexical representationof a signalimposes some restriction on Motfish (NottinghamTrent Univ., Nottingham NGll 8NS,UK) the acoustic-phoneticstage of processingof the signal.Furthermore, when The aim of this paperis to test the hypothesisthat broadphonetic the two itemsof the pairswere playedbinaurally rather than dichotically, categoriesiV. Zue,Proc. IEEE 73, 1602-1615(1985)] can act as a contact the migrationrate increased substantially, but the siz• of the lexicaleffect representationfor lexicalaccess. The resultsof thiswork will be consid- remainedunchanged. However, the lexical effect disappearedwhen the eredin termsof implicationsfor the neighborhoodactivation model. The migratingvowel was located in the stressedsyllable of the stimuli.In this techniqueused in thisexperimem was "phonetic priming" [A. Jongman condition,the lexical resistance collapses and words become as susceptible andJ. Sereno,Working Papers Cornell Phon. Lab. 7, 151-176(1992)]. to migrationsas nonsensewords. This secondresult may suggestthat Subjectswere asked to makea lexicaldecision about a targetword which lexical accessis initiatedon strongsyllables of words:when the stressed waspreceded by a subphonemicprime (either an ambiguous fricafive or an syllableis mispronounced,lexical access is impaired,eliminating the lexi- ambiguousstop). The primeeither matched or mismatchedthe manner of cal effect.[Work supported by AFOSR,NIMH, andBAEF.] articulationof the initial phonemeof the target.Reaction time results 4aSC6. Phonoiogicaland phonotoct'einfluences on perceptionof two showedan interactionbetween initial and prime, so that when these non-native vowel contrasts. Robert A. Avery and CatherineT. Best matched,the subjects' reaction time was inhibited. Furthermore the neigh- (Dept. of Psych.,Wesleyan Univ., Middletown,CT 06459 and Haskins borhoodeffect [Goldinger et el., J. MemoryLong. 28, 501-518 (1989)], Labs.,270 Crown St., New Haven,CT 06511) that wordsfrom a low-densitysimilarity neighborhood are recognized fasterthan words from a high-densityneighborhood, was enhanced by the Listeners'native phonology constrains their perceptionof nonqnatve presenceof thephonetically related prime. These results suggest that broad phoneticdistinctions. Although most non-nativecontrasts are discrimi- phoneticfeatures may activate lexical candidates. natedpooriy, recent findings that certaincontrasts are discriminatedwell led to developmentof a "perceptualassimilation model" (PAM), which 4aSC3. Multinomial modelsof speechperception. Court S. Crowther proposesthat the perceptualassimilation of non-nativephones to native (UCLA Phon.Lab., Dept. of Linguistics,Los Angeles,CA 90024-1543) categoriespredicts discrimination performance [e.g., Best et el., JEP:HPP and William H. Batchelder (Univ. of California,Irvine) 14, 345-360 (1988)]. The currentstudy investigated native pbonotactic It is often the casethat two differentacoustic cues can influenceper- influenceson threeassimilation patterns. Non-native contrasts that: (1) ceptionof bothof two adjacentphouemes within a syllable.In suchcases, assimilateto two categories(TC) and showexcellent discrimination; (2) it is of interestto determinewhether the cuesare evaluatedindependently; assimilateequally to a singlecategory (SC) andshow poor discrimination; that is, doesa listener'sevaluation of one cue influenceevaluation of the (3) assimilateas a categorygoodness difference (CG) and showgood othercue? Another, related question is whether,as some researchers claim, discrimination.American adults labeled and discriminatedlip-rounding phonemedecisions are dependent in thesense that, when cued by thesame contrastsamong Norwegian high front vowels [lil-lyl; lul-lyl] in CV's information,the decisionscompete for the information.This studymod- and CVC's. In both contexts,Norwegian fff of coursewas assimilatedto eleddam from a two factor,four categoryexperiment in whichFl offset English/i/;lu/was assimilatedto ltd. Althoughlyl wasassimilated equally frequencyand vowel duration cue both voicing and vowel identity in CVC to/ff or fff in CVCs, it was virtually alwayscalled/i/in CVs, compatible syllables.A familyof multinomialprocessing tree models [e.g., D. M. with the Englishphonotactic constraint against final lax vowels.Thus, Rieferand W. H. Batchelder,Psychoi. Rev. 95, 318-339 (1988)],of which lul-lyl showedTC assimilationand gooddiscrimination in bothsyllabic thefuzzy logic model of perceptionfor thetwo factor,four category design contexts.In CVs, lil-lyl showedSC assimilationand poordiscrimination; is a specialcase, was developedand testedto explorethe independence in CVCs, it showedTC or CG assimilationand gooddiscrimination. issues.This modelingapproach is highlyflexible and allows one to testa 4aSC7. Phonotaeficand metrical influenceson subjectiveratings of widerange of hypothesesregarding speech cue processing. spokennonsense words. MichaelS. Vitevitch,Paul A. Lace (Language 4aSC4. Talker variability and token variability in spoken word PerceptionLab., Dept. of Psych.,SUNY, Buffalo, NY 14260), Jan recognition:Effects on repetitionpriming in lexical decisionand an Charles-Lace,and David Kernmeter (SUNY at Buffalo) explicit recognitionmemory task. Emily A. Lyons (Language PerceptionLab., Dept. of Psych.,Park Hall, SUNY,Buffalo, NY 14260) This researchexamined English speakers' intuitions about the phono- logical "goodness"of nonsensewords. Subjectsrated bisyllabic,CVC- Recentresearch (e.g., Goldinger, 1993) has suggested that representa- CVC nonsensewords that varied in phonotacticprobability and stress tionsof spokenwords in memorymay be veridicalexemplars that encode placement.Using a ten-pointscale, subjects judged how English-likethe instance-specificinformation, such as characteristicsof the talker'svoice. nonsensewords sounded.Although all nonsensewords were phonotacti- This accountof spokenword recognitionwas examined in work presented caIly legal in English,subjects showed strong preferences for stimuli com- at a recentmeeting of the AcousticalSociety (Lace and Lyons, 1994). posedof highly probablephonotactic contributions. Moreover, subjects Evidencewas presentedin supportof the claim that exemplar-typerepre- judgednonsense words with strong-weakstress patterns as constituting sentationsare used in explicit recognitionmemory tasks, but that more "better"sounding English words than nonsense words with weak-strong abstractrepresentations play a role in taskssuch as lexicaldecision. How- patterns.No interactionbetween phonotactic probability and stresswas ever,the previouswork did not makeclear the explicitnessof the infor- observed.These results will bediscussed in lightof recentfindings regard- mation encodedin exemplar-typerepresentations; specifically whether ing adults'(Auer and Lace, 1993) and infants'(Jusczyk, Luce, and only grossfactors such as talker variationare encoded.or whetherwithin Charleg-Luee,190zl) •engitivity to the phonotactic configurations of spoken speakervariation is alsoencoded. The presentresearch expands on these stimuli.[Work supported by NIDCD.] previousresults by comparingthe effectsof talker variationand same- 4aSC8. The segmental representation of words as revealed by speakertoken variation on a repetitionpriming and an explicitrecognition priming in a lexical decisiontask. JamesR. Sawuschand Nancy J. memorytask. [Work suppot•ted by NIDCD.] Palmer (Dept. of Psych.,Park Hall, SUNY, Buffalo,NY 14260) 4aSC5. Lexical influence on the perception and segmentation of speech:Evidence from the migration paradigm. Sven L. Mattys and In previousstudies, a primingtask has been used to explorethe nature ArthurG. Samuel (Dept.of Psych.,SUNY at StonyBrook. Stony Brook, of thesegmental representation of words. The phonetic overlap between a NY 11794-2500) primeand a targetwas varied and the speedof namingor lexicaldecision to the targetexamined. The previousresults showed that when phoneroes The presentstudy addresses the issue of lexicalinfluence on perception occurredin thesame syllable position in primeand target, responses to the througha new paradigmbased on the migrationof linguisticunits from targetwere faster than for controltrials where the prime and target had no one ear to the other when two stimuliare presenteddichotieally. For ex- phoneroesin common.In contrast,when prime and targetshared pho- 3362 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3362 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp nemesbut the positions of thephonemrs in primeand target were different, differencebetween subject groups when only relative amplitude informa- nofacilitation of targetresponses was found. In a newseries of studies,this tionwas manipulated, but significantdifferences when both relative am- resultis furtherexamined using new stimuli and a dichoticpriming format. plitudeand formant transition information was present. Results from ex- Resultswill bediscussed in termsof theirimplications for thenature of the periment2 indicatedthat vowel duration influenced the useof relative abstract,segmental representation that underlies word recognition and lexi- amplitudeby listeners with normal hearing, but did not have this effect for calaccess. [Work supported by NIDCD GrantDC00219 to SUNYat Buf- listenerswith sensorineural hearing loss. [Work supported by NIH.] falo.] 4aSC12. Readingdisability: A deficit in the processingof rapid 4aSC9. Are coronals different? The influence of the lexicon on spectralchanges or in phonologicalcoding? Maria Mody (Dept.of coronal identification. Rochelle Newman, James R. Sawusch, and Otolaryngol.,Kennedy Ctr., Albert Einstein College of Medicine,1300 PaulLuce (Dept.of Psych.,Park Hall, SUNY,Buffalo, NY 14260) Morris Park, Bronx, NY 10461) and Michael Studalert-Kennedy (HaskinsLabs., New Haven,CT 06511) In previousstudies of lexicaleffects on phonemeidentification, robust effectshave been reported for voicingseries with noncoronalplaces of Reading-impairedchildren have been said to sufferfrom an auditory articulation(e.g., Ib/-Ip/or Ig/-lkl). Thesesame effects have been much deficit,indexed by difficultiesin processingformant transitions [P. Tallal, morevariable, smaller, and often absent for coronalvoicing series (Idl-ltl). Brain& Lang.9, 182-198(1980)]. Having established that poor readers Previously,results were presented suggesting that neighborhood density (n=20) madesignificantly more errors than good readers (n=20) ondis- couldhave effects similar to thoseof lexicalstatus in phonemeidentifica- criminationbetween stop-vowel syllables, contrasting in initial F 2 andF 3 tion tasksfor noncoronals.For coronals,neighborhood density did not transitions(/ba/and/da/), but not between nonspeech sinewave analogs of havean effect,again paralleling the lexical results. In newstudies, addi- F 2 andF3, thepresent study compared the same groups on identification tional coronal stimuli have been tested. Series have used word-nonword of (i) a/sel-ste•/syntheticcontinuum, where F• transitioncued the con- series to examine the influence of lexical status and nonword-nonword trast,and (it) twohybrid/su-•u/continua, each biased toward one end (Is/ seriesto examinethe influenceof lexicalneighborhood (the numberof orI]'l) o• a syntheticfricative series by the formant transitions of naturally wordssimilar to the target).The new stimuliincluded/dl-lt/series where spokenvowels. Poor readers did notdiffer from good readers in phoneme the initialstop is partof a consonantcluster. The resultsfor/d/-/t/series boundaries,but did exhibitshallower identification functions, significantly in clustersshow robust lexical influences on phonemeidentification. These so on the fricativecontinua. The resultsdo not supportthe hypothesized resultswill be discussedin termsof their implicationsregarding the status auditorydeficit: Less' consistent discrimination or identificationby poor of coronalsand the natureof consonantsin clusters.[Work supported by readerson speechtasks but not on the nonspeechcontrol task, suggests NIDCD GrantDC00219 to SUNY at Buffalo.] phonologicalrather than auditory difficulties. 4aSC10. The acousticcharacteristics of babble produced by infants 4aSC13.Interrelationships between ethanol intoxication and speech. with and without early onset otitis media with effusion. Susan HarryHollien (Inst.for Advanced Study of theCommun. Process., Univ. Rvacbewand EIzbietaB. Slawinski (Dept. of Psych.,Univ. of Calgary, of Florida,Gainesville, FL 32611) and Camilo A. Martin (Chemical 2500 UniversityDr. NW, Calgary,AB T2N IN4, Canada) AbuseTreatment Ctr., Veterans Admin. Med. Ctr., Gainesville,FL 32601) Prelinguisticspeech development was studiedlongitudinally in two Thefocus ofthis paper ison (1) establishing •vell-controlled proce- groupsof infants:nine infants in theearly onset group experienced their dureswhich will permitreasonably precise study of the effectsof intoxi- firstepisode of otitismedia with effusion (OME) at or beforethe age of 6 cationon speechand (2) assessingcorrelations between physiological and months;nine infants in the lateonset group experienced no OME before9 behavioral measuresof intoxication. In the first instance, selection and monthsof age.All childrenwere assessed at 6, 9, 12, 15, and18 months exclusionarycriteria will be discussedand their impact on theresulting of age.Each assessment consisted of an audiometricassessment and a experimentsnoted. Included will be (I) subjectselection (familial history, recordingof babble/speechproduced by the infant. Acoustic analysis of the background,health, gender, drug/medication status, drinking patterns), (2) babble/speechsamples revraled the following: all infantsshowed an in- dosageprotocols (control over and monitoring of intoxication,modifica- creasein the frequencyof canonicalbabble with age,when canonical tions),and (3) procedural constraints (speech tasks, experimental controls). babbleis definedaccording to thehcoustic criteria suggested by Oiler[in Someof thecriteria and procedures employed proved satisfactory, others B. Lindblom and R. Zetterstrom(Eds.) Precursorsof Early Speech did not andhad to be modified.Second, two aural-perceptualexperiments (1986)]; the meancanonical babble ratio was greaterfor the late onset (eighttalkers, 106 auditors) will bereported; a scaling model was used in groupin comparisonwith the early onsetgroup at all age levels;the the first, three variationsof a blind sort procedurein the second.Two vowelsproduced by someinfants with recurringor chronicOME were patternsof subjectbehavior were found; one correlated well with the characterizedby a restrictedrange of secondformant values. These find- physiologicalmeasures of intoxicationbut the other did not. Moreover, the ingssuggest that the canonical babble ratio may be a usefulmeasure for differencesin thespeech shifts did notappear directly related to subjects' investigatingthe relationship between OME andspeech delay in infants drinkingpatterns. [Research supported by NIH.] andyoung children. [Work supported by MRC.] 4aSC14.Shifts in fundamentalfrequency and articulationresulting 4aSCI1. Effect of relative amplitude,presentation level, and vowel from intoxication.G. Allan Alderman,Harry Hollien, Camilo Martin, durationon perceptionof voicelessstop consonantsby normal and andGea DeJong (Inst.for AdvancedStudy of the Commun.Process., impairedlisteners. Mark S. Henririck (Dept. Commun.Disorders, Univ. of Florida,63 Dauer Hall, Gainesville,FL 32611) Univ.of Alabama,Tuscaloosa, AL 35487)and Walt Jesteadt(Boys TownNatl. Res.Hosp., Omaha, NE 68131) Twogroups of subjectswere administered controlled doses of alcohol while breathalcohol concentration (BrAC) measurementswere made at In thepresent study, pibvious work on the influence ofrelative ampli- regularintervals. They were recorded reading a 30-spassage when they tudeand presentation level in listenerswith normal hearing and those with reachedpreset BrAC windows.Fundamental frequency measurements sensorineuralhearing loss is extendedto include(1) a comparisonof rela- werecalculated and compared for sober (0.00 BrAC) and intoxicated (0.12 tiveamplitude manipulation in the presence of neutralformant transitions BrAC)productions. The number of misarticulationsoccurring during the versusmanipulation of both formant transition and relative amplitude and readingsalso were assessed. In the first study, subjects were grouped on the (2)the additional variableS'of vowel duration. Synthetic CVstimuli were basisof whetherthey were rated as sounding intoxicated at 0.12BrAC used,and the amplitude of theburst relative to thevowel in theF4-F5 (ratingswere performed by50 auditorsusing a 5-pt.scale). Subjects who frequencyrange was varied across a 20-rib range,In experiment1, some soundedintoxicated were placedin one group,while thosethat did nol stimuli had neutralformant transitionvalues and relative amplitudema- wereplaced in a second.The first group showed a consistent, but statisti- nipulations;other stimuli had both formant transition and relative ampli- callynonsignificant decrease in F0 asa resultof intoxication;group 2's tudemanipulations. For stimuli in experiment2, neutralformant transition F0 changeswere not consistent.In addition,the firstgroup showed a valueswere used, relative amplitude was manipulated, and vowel duration highermean increase in misarticulationsthan did group2. The second rangedfrom 14 to 200ms. Results from experiment showed no significant populationwas'grouped bydrinking level (heavy, medium, or light); none 3363 d.Acoust. Soc. Am., Vol. 97, No.5, Pt.2, May1995 129thMeeting: Acoustical Sociely of America 3363 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp showeda statisticallysignificant change in F0. Moreovex,misarticulations post-operatively.Attempts were made to accountfor thespeech changes by increased(nonsignificantly) as drinking level increased.The resultswill be incorporatingthe anatomicalalterations caused by surgeryinto a speech correlatedwith datafrom otherstudies. [Research suppormd by NIH.] productionmodel. [Work supported by NSF NIH, andLeBel fellowship.] 4aSC15. Speaking rat• and alcohol intoxication. Gea DeJong,Harry 4aSC18.Intraspeech masking in hearing-impairedlisteners. Van Hollien, Camilo Martin, and G. Allan Alderman (Inst. for Advanced Summersand Marjorie R. Leek (Army Audiol. and SpeechCtr., Walter Study of the Commun. Process., Univ. of Florida, 63 Dauer Hall, ReedArmy Med. Ctr., Washington,DC 20307-5001) Gainesville,FL 32611) Upwardspread of masking(USM), themasking of an acousticsignal Eighteensubjects were recordedat five differentlevels of intoxication: by energyat lower frequencies,tends to increasewith presentationlevel i.e., at BrAC levels of 0.00, 0.04-0.05, 0.08-0.09, 0.12-0.13, and 0.09- andis morepronounced in listenerswith sensorineuralhearing impairment 0.08. Two of the speechtasks completed were: reading a standardpassage (HI listeners)than in normal-hearing(NH) listeners.At highpresentation and repeatingdiadocbokinetic syllables as fast as possible.The effectsof levels,HI listenersmay experiencea decreasein the cuesavailable from intoxicationon speakingrate were measured by thetime neededto readthe higherfrequency regions due to maskingproduced by high-amplitudefirst rainbowpassage and produce20 utterancesof "pataka,""shapupi," and formant(FI) resonances.In thepresent study HI andNH listenerslabeled "buttercup."The firstof thesereflects the subjects'ability to sustainmotor syntheticconsonant-vowel stimuli at moderateand high presentationlev- speechand the secondtheir motorspeech com•tence. Althoughvariation els. F1 regionswere attenuatedby 0, 6, 12, or 18 dB to test whetherF! wasobserved among speakers, the overalltendency was for boththe dia- attenuationmight reduce USM, makingcues present at higherfrequencies dochokinetictest and the rainbowpassage to increasein length(s} from more available.Performance was testedin quiet and in broadbandnoise sober(BrAC=0.00) to the intoxicatedlevel (BrAC=0.12). Further,the sufficientto maskinitial consonantalbursts. For both groupsof listeners, auralperceptual experiments carried out in parallelsuggest that listeners noise reducedlabeling accuracy.For normal-hearinglisteners, perfor- might use rate whenjudging the level of intoxication.That is, speakers mancewas not affectedby presentationlevel or FI attenuation.While judgedas highlyintoxicated at 0.12 BrAC (ratingswere performed by 50 someHI listenersshowed clear improvementsin labelingwith F1 attenu- auditorsusing a 5-pt. scale)exhibited a meandifference of 3.05 s between ationand/or increases in presentationlevel, the patramdid not hold across sober and intoxicatedutterances, whereas those speakerswho did not the entiregroup. The resultswill be discussedin light of the severityand soundintoxicated showed a meandifference of 0.05 s. [Researchsup- configurationof the individualheating losses. portedby NIH.] 4aSC19. Acoustic and perceptual investigation of breathy voice. 4aSCI6. Predicting speech improvement from clinical profiles in RatteeWayland, Scott Gasgash, and Allard Longman (Dept. of Modem stutterers. Peter Howell (Dept. of Psych.,Univ. College London, Lang.and Linguistics, Cornell Univ., Ithaca,NY 14853) GowerSt., LondonWCIE 6BT, England) Althoughbreathy voice is typicallycharacterized by an increasein Proceduresfor assessingdysfiuencies in stutteredspeech have the limi- spectralnoise, it is notoriouslydifficult to devisea computationalmethod tationthat they show poor int_er-judge agreement. This constitutes a serious to distinguishbreathy from clear(modal) voice. The presentstudy suc- problemfor, amongstother things, assessing how a stutterer'sspeech ben- cessfullymakes use of an algorithm,originally developed to quantifyas- efits from therapy.A critical review of alternativeprocedures that are peelsof pathologicalvoice quality [G. de Krom, J. SpeechHear. Res. 36, availableindicates that theydo not offer any betterprospect for assessing 254-266 (1993)],which computes a harmonics-to-noiseratio (HNR). The improvementsdueto treatment than do the traditional pro•dures. Several algorithmcalculates the harmonics-to-noiseratio usinga combfilter de- factorsare identifiedwhich might lead to the limitationin agreement.A fined in the cepstrumdomain to separatethe harmonicsfrom the noise. new procedurewhich overcomessome of the problemsidentified was Performanceof the algorithmwas testedon three speakers(2 rnale, 1 devisedand applied to a groupof stutteringchildren before and after they female)6f Javaneseproducing a wordlist of 31 minimalbreathy/clear receiveda 2-weekintensive therapy course. The new procedureproduced word pairs. Results showedthat the algorithmreliably distinguished substantiallyhigher levels of agreementthan thosereported in the litera- breathyfrom clear tokensfor all three speakers,with higherHNRs for ture. This procedureis used to measurethe benefit each individual child clearthan for breathytokens. Moreover, accurate performance was ob- achievedafter treatment.Clinical review data on these•hildren were then tainedfor nearlyall frequencyranges investigated (60-2000 Hz, 2000- employedto seewhether any aspectof the interviewcould have predicted 3000 Hz, 3000-5000 Hz). A comparisonto othermethods (such as HI- the child'sresponse to treatment.The child'sgeneral health and cognitive H2) will alsohe presented.Finally,'perceptual rating experiments will he skillsappear to he reliableindications as to treatmentprognosis. [Work conductedto determineif the algorithm'sperformance correlates with per- supportedby MRC.] ceived degreeof breathiness. 4aSC17.Acoustic and perceptualeffects of endoscopicnasal surgery. 4aSC20. Modeling pathologicvocal quality. Part I. Jody Kreimau MarilynY. Chen (Res.Lab. of Electron.and Dept. of HealthSci. and andBruce R. Gettart (Div. of Headand Neck Surgery, UCLA Schoolof Technol.,MIT, Rm. 36-511, Cambridge,MA 02139) and RalphMetson Medicine,31-24 RehabCtr., LosAngeles, CA 90024-1794) (MassachusettsEye andEar Infirmary,Boston, MA 02114) Previousstudies of pathologicvocal quality have not yieldeda stan- The aim of thispaper is to determinethe effects of surgicalalterations dard set of scalesfor describingdisordered voices, possibly due to the of nasalanatomy on the spectral characteristics and perceptual attributes of limitednumber of voicesstudied. The pre•entstudy uged large getg (n = go) speech.Five patiemswho underwentendoscopic nasal surgery were re- of maleand femalevoices, representing a broad range of diagnosesand cordedprior to surgery,and i week and i month after surgery.The utter- vocal severities.Eight expertsjudged the dissimilarityof each pair of anceswere six vowel types adjacentto nasal consonantsand stop conso- voices,and responseswere analyzedusing nonmetricindividual differ- nants.In additionto endonasalsurgery enlarging the sinusopenings, some ences multidimensionalscaling. Results indicate that differencesbetween patientshad a correctionof deviatedsepturn, resection of a turbinate,or listenersin perceptualstrategy are so greatthat the fundamentalassump- removalof polyps.Acoustic analysis was carried out for nasalizedvowels, tion of a commonperceptual space must be questioned.Group spaces non-nasalizedvowels, and the nasalconsonants Im/and/n/. Significant revealeda single"feature" (severity of pathology).Spaces for individual differencesin spectralproperties were observedin the consonantsand listenerswere characterizedby clustersof voiceswhich seemedstructured nasalizedvowels recorded before and after surgery.For example,changes by "family resemblances":Each voice in a clusterresembled others with were found in the prominenceof extra peaksdue to nasalizationand the rspectto someproperty, but the sameproperty did not constitutethe re- first formant bandwidth was narrower for the nasal consonants and nasal- semblancefor all voicepairs. Further, voices did not appear consistently in ized vowels.All exceptone patient perceived a changein their speech thesame clusters across listeners. In theabsence of a commonperceptual 3364 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3364 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp space-•ofa sharedsense of howvoices sound similar--valid perceptual Velotracedata for a numberof differentutterance types, including those scalescannot be defined. The results lead to the conclusion that standard- with stressedversus unstressed syllables and thosewith syllable-initial izatJonof perceptuallabels for voicequality is theoreticallyimpossible. versussyllable-final nasals. One consistent observation is that velum low- eringcan be quite extensive before acoustic effects are observed. [Work 4aSC21. EMMA and x-ray microbeam comparison. Dani Byrd supportedin partby NIH.] (Haskins Labs., 270 Crown St., New Haven, CT 06511-6695), CatherineP. Browman (HaskinsLabs.), Louis Goldstein,and Douglas 4aSC24.Use of a spikingneural modelto simulatelip motor unit Honorof (HaskinsLabs. and Yale Univ.) activityand movementsin speech. MichaelD. McCleanand John L. Clay (Audiol.and Speech Ctr., Walter Reed Army Med. Ctr., Washington, In thepast, much articulatory movement data have been obtained using DC 20307-5001) the x-raymicrobeam. Currently, however, magnetometer systems such as EMMA arebecoming predominant. A unique data set, addressing concerns of consistencybetween these instruments is reported. A singlespeaker was In orderto clarifythe nature of EMG-kinematicrelationships involved recordedwith both instrumentsreading the same utterances:"It's a in speechproduction, a rudimentary computer model of thelower lip asa [pV'CVp]again." Data from two x-raymicrobeam (XRMB) runswere neuromechanicalsystem was developed.The modelconsists of three collectedon the same day (pellets re-placed for thesecond run); 27 months muscleshaving forcing functions that act on a commonpoint. Each muscle laterthe parallelEMMA datawere collected. Vertical movement of the is treatedas a setof singlemotor units with associatedmoroneuron spike lowerlip, tonguetip, andtongue body during the VCV's wasanalyzed. activityand muscle-unit twitch forces. The temporalpatterns of moroneu- Extmmapositions (amplitudes) and distanceand time betweenthese po- ronspike trains, which serve as the system input, are based on singlemotor sitions(gestural displacements and durations) were obtained. The results unitEMG recordingsobtained during syllable repetition [M. McCleanand demonstratethat the correlationbetween EMMA and XRMB runs is very J. Clay,Society for NeuroscienceAbstracts 19, 229.15(1993)]. System high, almostas high as that betweenthe two XRMB runs. outputis evaluatedin termsof lower-lipmovement through the midsagittal plane.Simulations produce realistic movement patterns when they are constrainedby reasonableassumptions about motor unit intrinsicproper- r values(p<0.0001) amplitude displacementduration ties,muscle force angles, and relative timing of moroneuronspike trains. XRMB-1 & EMMA 0.9898 0.8615 0.7570 Initial applicationsof the modelhave focusedon the mechanismsof XRMB-2 & EMMA 0.9852 0.8948 0.7210 speechrate control. Different rates of syllableproduction are established XRMB-1 & XRMB-2 0.9901 0.9107 0.7933 by theoverall temporal patterns of moroneuronspike trains, and the effects of varyingsystem parameters are evaluatedat eachrate. Usingfurther analyses of varianceit wasconcluded confidently that the resultsobtained using EMMA for articulatorydata collection do notdiffer 4aSC25. Clarity versuseffort in speechproduction: Initial resultsof substantiallyfrom thoseobtained for similardata collectedat different a pilot study. JosephPerkell, Melanie Matthies, Mario Svirsky,and timewith the x-ray microbeam. [Work supported by NIH.] Reiner Wilhelms-Tricarico (SpeechCommun. Group, Res. Lab. of Electron.,Rm. 36-511,MIT, Cambridge,MA 02139) 4aSC22. An acousticand articulatory study of anticipatory labial coarticulation.Marlos Foumkis and Ying Xu (Dept.of Speechand Hear. Sci., Ohio State Univ., ll0 PresseyHall, 1070 CarmackRd., The goalof thisresearch is to testthe hypothesis that there is a trading Columbus,OH 43210) relationbetween clarity and effort in speechproduction. Midsagittal-plane articulatorymovements of pointson thetongue body, tongue blade, lips The acousticand articulatory aspects of anticipatorylabial coarticula- andmandible (with an EMMA system)and the acoustic signal from a male tion wereexamined. One female native speaker of AmericanEnglish read talkerin five speakingconditions: normal, clear, clear plus fast, fast, and a list containingten repetitionsof nonsenseV1CV2 sequenceswhere VI slow, were recorded.Different CVC words were embeddedin two posi- wasalways [i], C wasone of [s],[J], [z], [3], andV2 wasone of [i], [u], or tionsin a carrierphrase. Analyses were performed as a functionof speak- [a]. The movementof upperand lowerlip andjaw wererecorded using the ingcondition and position in thephrase. As anexample, CV movementsof strain gaugeapparatus developed by Barlow and colleagues,and the a pointon thetongue body for theword "cab" have the following char- acousticsignal was alsorecorded. Short term spectrawere takenof the acteristics.Movement duration was shorterfor positiontwo; in bothposi- fricativenoise at the beginningand at intervalsspaced at 0.25, 0.50, and tions, it followed the order: slow>clear>normal>clearplus fast>fast. 0.75 of the durationof the fricative.Two spectralpeaks were identified at Therange of distancetraveled was greater for slowand for clear,than the eachpoint. It waspredicted that the frequenciesof thosepeaks would be otherconditions. Peak velocity was higher for fastand clear plus fast than affectedby thenature of thefollowing vowel and that the coarse spectral theother conditions. Midsagittal plane location at movementend was less trackwould show a downwardmovement when the followingvowel was variat•lewith the longer duration movements ofthe word in position one. [u]. Neitherof thesepredictions obtained. This result is in agreementwith Effortwas higher for clear, clear plus fast and fast, than for normalor slow, theEMG data of Gelleret al. [J.Acoust. Soc. Am. 86, 2443-2445 (1989)] in bothword positions. [Work supported byN.I.D.C.D.] butnot with the acoustic data of, amongothers. Sereno et al. [J. Acoust. Soc.Am. 81, 512-519 (1987)]. Resultsfrom a secondspeaker and from 4aSC26.The gesturaland temporalorganization of assimilation. the analysisof the lip movementdata will alsobe presented. SidneyA. J.Wood (Dept.of Linguistics,Helgonabacken 12,22362 Lurid, Sweden) 4aSC23. Correlating movement and acoustic measures of nasalization. SharonY. Manuel (Res. Lab. of Electron.,Rm. 36-511, Ever•sinceWang and Fillmore [J. SpeechHear. Res. 4, 130(1961)] MIT, Cambridge,MA 02139)and RenaA. Krakow (TempleUniv., phoneticionshave distinguished between nonpredictable language-specific Philadelphia,PA 19122and Haskins Labs., New Haven,CT) speechhabits and predictable universal articulatory constraints, the former Previousresearch using physiological instrumentation (e.g., Velotrace) beingcortical and extrinsic to thevocal tract, the latter intrinsic to the hasshown systematic effects of syllablestructure and stresson velum vocaltract and the consequenceof articulationmechanics. Assimilation movements[Krakow, in Phoneticsand PhonologyV (Nasals,NasalJzation, came to be seenas an intrinsicvocal tract process,explained in termsof and the Velum,edited by Huffmannand Krakow (Academic, San Diego, •hman'smodel of coarticulation[J. Acoust.Soc. Am. 39, 151 (1966)]. 1993),pp. 87-113]. However, what has not been investigated previously is This contrastswith classicalphonetics where assimilation is the resultof thecorrespondence between the time-varying position of thevelum in such pmplannedreorganization of articulation. The work reported in thispaper data and the timing and magnitudeof acousticallydetectable nasalization. favors the classical view. Gestures involved in an assimilation are initiated A newtechnique developed by Chen[J. Acoust. Soc. Am. 96, 3283(A) earlier,delayed, or areheld longer, than in nonassimilatedsituations. It is (1994)]for identifyingthe spectral effects of nasalcoupling was found to arguedthat this revision of gesturetiming in relationto adjacentactivity is providea valuableway of linkingthe acoustic and articulatory changes an expressionof preplanningof motorcommands that takes place in the relatedto velopharyngealport aperture. This paper reports on acoustic-to- cortexwhere them is accessto largerportions of the utterance(the sub- articulatorymapping using acoustic data collectedin concertwith corticalmotor structureshave limited accessand cannotadvance or delay 3365 d.Acoust. Soc. Am., Vol. 97, No.5, Pt.2, May1995 129thMeeting: Acoustical Society of America 3365 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp gestures).Examples of palatalizationof Bulgarianapico-alveolar stops and seekingcorrelations between acoustic and perceptual measures will never Swedishpalatovelar stops are presented.The data are analyzedfrom x-ray produceconsistent, replicahie associations, because individual differences motionfilms by proceduresdescribed by Wood[J. Phon.19, 281 (1991)]. in perceptualstrategy are so greatthat uniquemappings do not exist,as 4aSC27. Modeling pathologicvocal quality. Part IL BraceR. Gerratt arguedin PartI. It is believedthat the difficulties in establishingacoustic- and $odyKreiman (Div. of Headand Neck Surgery,IJCLA Schoolof perceptualrelations in voice researchcan be solvedonly by modeling Medicine,31-24 RehabCtr., Los Angeles, CA 90024-1794) qualityas an interactionbetween a particularlistener and voice, rather than asa propertyof thevoices themselves. An analysis-by-synthesismethod is The utility of acousticmeasures of pathologievoice depends on their describedin which listenersconstruct a syntheticsignal to matcha par- consistentcorrespondence to physiologicalstates or to what listenershear. UnfortUnately,such consistent patterns of associationhave never emerged, ticularnatural voice. In this way, listeners'perceptions are definedobjec- despitemany years' reseach. Attempts to mapfrom acoustics to physiology tively by the valuesof the synthesizerparameters they select.This ap- may neverproduce unique associations. because many physiological con- proachexplicitly links acousticrepresentations to perceivedqualities, thus figurationsmay produceequivalent acoustic signals. Similarly, studies reducingconcerns about utility and validity in both domains. FRIDAY MORNING, 2 JUNE 1995 GRAND BALLROOM SOUTH, 7:55 A.M. TO 12:05 P.M. Session 4aUW Underwater Acoustics:Transient Sounds: Their Measurement and Description Charles R. Greene, Chair GreeneridgeSciences, Inc., 4512 Via Hueno, SantaBarbara, California93110 Chair's Introduction--7:55 Invited Papers 4aUWl. Acoustic transients researchat the Naval ResearchLaboratory. StevenFinette, Peter C. Mignerey,Robert L. Field, and EdwardR. Franchi (Naval Res.Lab., Washington,DC 20375 and StennisSpace Center, MS 39529) From 1988 to 1992 the Naval ResearchLaboratory conducted basic research in acoustictransients. This paperwill summarizethe key resultsof that research.First, the time-domainparabolic equation model was developedto predictthe effectsof the ocean environmenton•coustic transient signals. Comparisons between modeled and measured ocean impulse responses will bereviewed and theability of themodel 'to predict signal feature distortion will 'be shown for data from an Atlantic, downward refracting, range- dependentenvh'onment. Second, the development of a multi-sensoraleconvolution estimator which makes full useof anarray aperture will be discussed.Use of the full array apertureensures that no part of the impulseresponse spectrum drops out due to poor illumination.Multi-sensor deeonvolution processors based on thisprinciple have produced stable reconstructions of source time-series. Datawill be shown that illustrate successful n•ulti-sensor deconvolution thatwas obtained by a large,vertical, line-array in a deep Pacificenvironment for source-receiverseparations of 1-2 convergencezones. Third, time-domainhigher-order correlators were developedfor the detectionand time-delayestimation of short-time/broadbandtransients. The signaland environmentalconditions requiredfor higher-orderprocessors to outperformconventional cross-correlators will be shown. 8:20 4aUW2.Transient signals-based sonar systems. Jaraes E. Barget (BBN Systemsand Technologies, 70 FawcettSt., Cambridge, MA 02138) Thedetectability of signals(echoes) depends only upon the energy and bandwidth of thesignals, in a widevariety of different interferencebackgrounds. This fact is representedin a sonarequatioc• that is bothwritten in termsof thesequantities, and that also differsfrom the moretraditional form that incorporated signal power and time span.Beyond this, fluctuations in thetransient signal's arrivaltimes, time spreads,arrival angles, and angle spreads; all affecttarget localization processing. Since a transientsignal has a shortertime s[•an than does a longerwaveform with equal energy, the effects of propagation-inducedfluctuations between successive transientsignals can b• different than betweensuccessive long-waveform signals. The potentialfor thesedifferences is discussedfor four differentcauses of fluctuation;multipath, refraction, direct-path fluctuation, and reflectedpath fluctuation. 8:40 4aUW3.Quantitative calibration and characterizationof marineseismic sources. J. RobertFricke (Dept.Ocean Eng., Rm. 5-218, MIT, Cambridge,MA 02139) In the mid '80s the offshoreseismic exploration industry needed a standardproc•inre for describingtransient seismic source signatures.The need was motivated by severalissues including a needto specifyperformance criterion to theoperations crew, a need to evaluateone source versug another for a particularseismic program, and the need to determineperformance fo3 new seismic source designs.Prior to thattime, seismic source signatures were usually described in thetime domain' in termsof peak-to-peakpressure (bar-m)and peak-to-bubble ratio. Spectral characterization, if it exis•l, wasrelative to thepeak value, which was usually set to 0 dB. 3366 J. Acoust.Soc. Am., VoL 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3366 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp Thesemeasures do notprovide quantitative descriptions of sourceenergy or spectralenergy density, hence a quantitativestandard was neededand developed. The standardfocused on a spectral,rather than a temporal,description of theseismic signature and allowed for a detailedanalysis of the totalsource energy and the distribution of thatenergy as a functionof frequency.This approachopened the way for a consistentand quantifiable description of the sourcesignature. Using this description, the above mentioned needs regarding performanceand evaluationcould be addressed. 9:00 4aUW4. Metrics and standardsfor acousticenvironmental assessments. Raymond C. Cavanaghand John S. Hanna (Science ApplicationsInt'l. Corp.,McLean, VA 22102) Becauseof stringentlegal requirements and growingpublic interest, researchers must win governmentapproval for any seatest involvingacoustic emissions which could injure or harassmarine animals. The approvalprocess requires extensive documentation on the animalsin the testarea and likely impactof the test.This documentation(Environmental Assessment or EnvironmentalImpact Statement)then includes predictions of shockwave and acoustic field characteristics in terms relevant to animalharassment and injury metrics.At present,there is no "standard"approach to developingan EA or an ElS; eachresearch program provides its own format, metrics,etc. This presentationconsiders issues of standardizationfor the EA andElS processes.In particular,literature on animal effectsprovides a varietyof empiricalthresholds in variousunits (e.g., peak pressure, impulse), while source metrics have their own particularunits (e.g., energy density at range,intensily). Finally, signal must be estimated with a modelthat correctly propagates the quantityof interestin complexenvironments. None of thesesteps has a standardapproach. Examples are given of problems encounteredand recommendations made for standardization.Special attention is givento measurementtechniques for marineanimal responseto sound. 9:20 4aUW5.Fourier and directtime-marching methods for transientsignals. MichaelB. Porterand Zoi-Hcleni Michalopoulou (Ctr. for Appl. Math. and Stat.,New JerseyInst. of Technol.,Newark, NJ 07102) The oceannormally vibrates in harmonywith thehum of a narrow-bandsound source. Thus, for modelingsuch signals, time can be removedfrom the waveequation reducing it to the simplerHelmhohz equation which in essencegoverns only the intensity of the hum.Computational ocean acoustics has most often focused on thislatter case. Broadband signals such as pings,clicks, chirps, and gurglesrequire far morework. For researchersaccustomed to narrow-bandmodels the fastestapproach is usuallyto simplyadd a frequencyloop to theirnarrow-band codes. (Of course,the mn timegoes up in accordancewith the number of frequenciesrequired.) Othershave advocated the development of newmodels that solve the wave equation directly in thetime domain. These options are surveyedand illustrative examples are provided using both idealized test cases and measured data from a recentexperiment in theGulf of Mexico. 9:40-9:50 Break ContributedPapers 9:50 portentof theAcoustic Thermometry of OceanClimate (ATOC) Program. Preliminaryresults are presented.Three-minute averaged spectra were ob- 4aUW6. Transient sounds in marine seismology. R. A. Stephen tainedevery 5 rain;only the relativenoise level as a functionof frequency (WoodsHole Oceanogr.Inst., Woods Hole, MA 02543) is presentedbecause (at thistime) unknown offsets prevent determination In marineseismology two lypesof transientsound sources are used. of absolutelevels. One important statistic estimated is theprobability as a Controlledsources such as airgunsor explosionsare usedin seismicre- functionof frequencythat the noise level exceeds a specifiedspectral level. fleetionand refractionsurveys to study geologicalstructure below the [Worksupported by the StrategicEnvironmental Research and Develop- seafloor.Naturally occurringearthquakes are also observedand they are mentProgram through ARPA.] usedto studytectonic and regional and whole earth structureproblems. In both casesthree-component particle motion, either velocity or accelera- 10:20 tion, is measured on or within the seafloor. However controlled source studieswork in the VLF band(l.0-100 Hz) and earthquakestudies gen- 4a[iW8. Are ANSI standards for describing airborne impulses erallyrun in the lower ULF band(0.001-5 Hz}. A majoradvantage of applicableto underwatertransienls? Charles R. Greene (Greeneridge transientsources versus harmonic sources is that multi-pathingcan be Sciences,Inc., 4512 Via Huerto, Santa Barbara,CA 93110-2324) and distinguishedby the time separationof phases.In fact, manyschemes for FrankT. Awbrey (San Diego StateUniv., San Diego, CA 92187-4614) inferringgeological structure from transientseismic data are basedsolely ANSI standardsexist for measuringand assessingairborne impulsive on the arrivaltimes of certainphases. Also time spread (coda or signal- sounds.This paperreviews those standards and considers their applicabil- generatednoise) can be observeddirectly as reverberationafter the coher- ity and utility in measuringand assessingunderwater transient sounds. ent arrivals.The polarizationof the separatedphases can be usedto study propagationeffects. Examples of quantitativedata of bothcontrolled and earthquakesources will be shownand discussed. 10:35 10:05 4a[iW9. The Bragg condition limitation on inversion of normal incidencereflection data, KennethE. Gilbertand TimothyJ. Kulbago 4aUW7. Low-frequency ambient noise: Long time series and (Appl. Res.Lab. and the GraduateProgram in Acoust.,Penn State Univ., statistics. Keith R. Curtis,Bruce M. Howe, and ShaunLeach (Appl. P.O.Box 30, StateCollege, PA 16804) Phys.Lab., Univ. of Washington,Seattle, WA 98105) A simpleanalytic expression is derivedfor the impulseresponse of a Low-frequencyocean ambient noise spectra have beencollected at continuouslystratified sediment. The expression,which neglectsmultiple U.S. Navy PacificSOS[IS sitesduring the last year as a backgroundcom- scattering,allows a straightforwardcalculation of boththe forwardand 3367 d. Acoust.Sec. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3367 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp inverseproblem, but more importantly,it clearlyestablishes the "Bragg 11:05 condition" as a fundamental limitation on the inversion of acoustic data dominatedby singlescattering. (For normalincidence backscatter, the 4aUW11. Timespreadmodeling of propagatingpulsed and transient Braggcondition states that an acousticprobe signal of wavelengthk senses underwater signals. Ellen M. Daley, Ruth E. Keenan,and AnthonyI. or "filtersout" only the Fouriercomponent of the impedanceprofile hav- Eller (OceanSci. Group, SAIC, 1710Goodridge Dr., McLean, VA 22102) ing wavelengthM2, i.e., Xmeaium=h.ammtic/2.) The validityof the analytic Many Navy standardand other widely used underwater acoustic propa- expressionis demonstratedby comparingit with exact numericalcalcula- gationmodels were developedthrough an evolutionaryprocess to address tions for both the forward and inverseproblem. In particular,it is shown applicationsfeaturing narrow-band or single-frequencycw signals.A con- that to obtaintrends in impedancethat occurover meters,requires a probe sequenceof this developmentprocess is that, althoughthe modelsmay signalwith wavelengthsof approximatelytwice the desiredtrend distance. handlethe originally intendedproblem very well, they are not necessarily Many high-frequencyinversions reported in the literatureshow trends with able to describethe propagationof high resolutionpulses or transients, wavelengthsthat are orders of magnitudelarger than any wavelengthin the where time-domainor multi-frequencyFF'r approachesseem called for. probesignal. Consequently, it is worthwhileto askwhether the longwave- This paper presentsthe resultsof an evaluationof severalpropagation lengthtrends, which cannot be acousticallysensed by the shortwavelength modelsto characterizeshort duration signals. The modelstested represent probesignals, are physicallymeaningful, or whetherthey are artifactsof a varietyof physics-basedapproaches: parabolic equation, rays and Gauss- arbitraryunderlying assumptions in the signal processing method. [Work ian beams,modes, and hybridapproaches. The evaluationcriteria include supportedby NRL andONR.] an abilityof the modelingsystem to accommodatereal-world, in-situ en- vironments,accuracy of the resultsin the contextof intendedapplications, and reasonable execution time. 11:20 10:50 4aUW12. Theory and experiment of pulse propagation in shallow 4aUW10. Localization of sources of acoustic transients using a water. RenheZhang (StateKey Lab. of Acoust.,Chinese Acad. of Sci., broadbandmatched-field processing technique. F. D. Tappert (Appl. Beijing 100080, People'sRepublic of China and Schoolof Mech. Eng., Marine Phys.,Univ. Miami, RSMAS, 4600 RickenbackerCswy., Miami, GeorgiaInst. of Technol.,Atlanta, GA 30332) and Ye Zhu (State Key FL 33149) and L. Nghiem-Phu (MAC SystemsCorp., Miami, FL Lab. of Acoust.,Chinese Acad. of Sci., Beijing 100080,People's Republic 33155} of China) By matching,or correlating,a complex-demodulated(envelope) time An experimentwas conductedin shallow water with strong ther- seriesmeasured at a single hydrophonereceiver to predictedenvelope mocline, locatedbetween the depthsfrom II to 15 m. Explosive sources responsefunctions obtained by back propagationusing a full-physics were detonated at 7 and 25 m, with receivers also at 7 and 25 m. Band- broadbandPE model,it is possibleto removemultipath distortion effects limited signalswith 1/3 oct bandwidthfor differentcenter frequencies and and to determine the location of the source of an acoustic transient with rangeswere analyzed. The waveformstructures are stronglydependent on good resolutionand high processinggain. This "semi-coherent"broad- sourceand receiver depths. center frequency, and range. A ray-modetheory bandmatched-field processing (BMFP) techniqueis demonstratedin sev- includingbeam displacementwas usedto calculatethe waveformstruc- eraldeep water and shallow water situations. [Work supported by ONR turesand to invertfor the bottom-lossversus grazing angle. The calculated andARPA.] waveform structures are consistent with the measured ones well. 11:35-12:05 PANEL DISCUSSION 3368 J. Acoust.Soc. Am., Vol. 97, No.5, Pt.2, May1995 129thMeeting: Acoustical Society of America 3368 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp FRIDAY MORNING, 2 JUNE 1995 MEETING ROOM 17, ROOM, 8:30 A.M. Meeting of AccreditedStandards Committee S12 on Noise to be heldjointly with the U.S. TechnicalAdvisory Group for Isofrc 43/SC1 Noiseand Isofrc 94/SC12Hearing Protection D. L. Johnson,Chair S 12 EG& G SpecialProjects, Albuquerque Operations, Albuquerque, New Mexico87119-9024 P. D. Schemer,Chair, US TechnicalAdvisory Group (TAG) for ISO/TC43/SC1, Noise (and Vice Chair S12) U.S. CERL, P.O. Box 4005, Champaign,Illinois 61820 H. E. vonGierke, Vice Chair, U.S. TechnicalAdvisory Group (TAG) for ISO/TC 43/SC1,Noise 1325 Meadow Lane, Yellow,Springs, Ohio 45387 Elliott H. Berger,Chairman, U.S. TechnicalAdvisory Group (TAG) for ISO/TC 94/SC12,Hearing Protection CabotSafety Corporation, 7911 ZionsvilleRoad, Indianapolis, Indiana 46268-1657 StandardsCommittee S12 on Noise,Working group chairs will reporton their progressfor the productionof noisestandards. The interaction with ISOfFC 43/SC1 and ISO/TC 94/SC12 activities will also be discussed, with reference to the international standards underpreparation. The Chairsof the respectiveU.S. TechnicalAdvisory Groups (H. E. vonGierke and E. H. Berger)will reporton current activities of these International Technical Subcommittees under ISO. Scopeof S12: Standards,specifications and terminologyin the field of acousticalnoise pertaining to methodsof measurement, evaluationand control;including biological safety, tolerance and comfortand physicalacoustics as relatedto environmentaland occupationalnoise. FRIDAY AFrFERNOON, 2 JUNE 1995 MEETING ROOM 3, 1:00 TO 5:00 P.M. Session4pAB Animal Bioacoustics:Recognition of Animal Sounds:Methods and Applications David K. Mellinger,Chair CornellBioacoustics Research Program, 159 SapsuckerWoods Road, Ithaca, New York14850-1999 Chair's Introduction--l:00 Invited Papers 1:05 4pAB1.Marine animal sound classification. Kurt M. Fristrupand William A. Watkins(Woods Hole Oceanogr. Inst., Woods Hole, MA 02543) Softwarewas developed to measurecharacteristics of marine animal sounds (AcouStat). These measurements included aggregate bandwidth,duration, amplitude modulation, frequency modulation, center frequency, and interactions among some of thesevariables. Thesemeasurements proved effective for describingand classifying sounds in severalcontexts: identifying species, quantifying the repertoireofa singlespecies, and identifying individuals. Our experience during development suggests that removal of noiseenergy anduse of robuststatistical measures are necessary to ensure repeatable results with open water recordings ofmarine mammal species. 3369 J. Acoust.Sec. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3369 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 1:30 4pAB2.Quantihative analysis of dolphinsounds. Peter L. Tyack (Dept.of Biol.,Woods Hole Oceanogr. Inst., Woods Hole, MA 02543) Most analysesof acousticcommunication in animalslump soundsinto qualitativecategories. These are usuallybased upon aural impressionsfor humanlisteners or visualinspection of spectrograms.Quantitative analysis of acousticfeatures from belugawhale soundsraise seriousquestions about how discreteand robustthe traditionalcategories of belugacalls are. Other categories,such as the contourof a dolphinwhistle, use features that need not relate directly to absolutemeasure of time andfrequency. Studies of vocal developmentand vocal imitation often benefit from a quantitativemeasure of similaritybetween sounds and putative models. Several differentmethods are compared to analyzewhistle contours, including multivariate analysis of time-frequencyfeatures, dynamic time warping,and a signalcompression approach. Ultimately, all suchtechniques need to be validatedby studiesof how eachspecies perceivesits own signals. 1:55 4pAB3.Comparison of the whistlestructure of six speciesof dolphin. WilliamE. Evans (TexasInst. of Oceanogr.,Texas A&M Univ.,P.O. Box 1675,Galveston, TX 77553), WangDing (Inst.of Hydrobiol.,Chinese Acad. of Sci.,People's Republic of China), and Bemd Wfirsig (TexasA&M Univ., Galveston,TX 77553) Spectraland statistical analyses were used to comparethe whistle structure of six speciesof dolphin;Stencils 1ongirostris, Stencils frontalis, Stenellaattenuata, Lagenorhynchus obscurus, Tursiops truncatus. and Sotaliafiuviatilis. A consistentpattem existed in the variouscoefficients of variationcalculated for the differentspecies. In general,the frequencyvariables had the lowestcoefficients of variation(cv). The valuesof cv for maximumfrequency were usually the lowest.Compared to otherspecies Tursiops had relatively largecoefficients of variationof the frequencyvariables indicating that the frequenciesof Tursiopswhistles were more diverse. The otherfive species had similar frequency ranges which had higher upper frequencies than Tursiops. The resultsof discriminateanalysis indicatedthat here were significant differences between the whistlestructures of the differenlspecies, and that these differences were relatedto taxonomicrelations, body size, and habitat. The magnitudeof thedifferences in whistlestructure correlated with taxonomic relationshipsof the variousspecies studied. The pelagicspecies emitted whistles in a relativelyhigher frequency range and greater frequencymodulation than the coastalor rivefinespecies. 2:20 4pAB4.Automatic detection and classificationof nocturnalmigrant bird calls. HaroldMills (CornellLab. of Ornitbol.,159 SapsuckerWoods Rd., Ithaca,NY 14850) Computersoftware was developedto detectthe nocturnalflight calls of nine speciesof migratingwarblers in digitizedfield recordings,and to classifythe calls by species.The calls are frequency-modulatedtones in the 5- to 9-kHz frequencyband, and between50 and 100ms in duration.Detection was accompanied by locatingtemporal peaks in call bandenergy. Some false detections of insectcalls were prevented by rejectingcertain types of peaks.Classification is approachedby trackingthe frequenciesof thecalls over time and classifyingthe frequencytracks with an artificial neuralnetwork. ContributedPapers 2:45 3:00 4pABS. Bird flight call discrimination using machine learning. 4pAB6. Vocal learning in Budgerigars (Melopsittacusundulatus) AndrewTaylor (Comp.Sci. and Eng., Univ. of NSW, Sydney2052, usingfood reward. KazuchikaManabe and Robert J. Dooling (Psych. Australia) Dept.,Univ. of Maryland,College Park, MD 20742) The developmentof a softwaresystem which can detectand identify Budgefigars(parakeets) are small, highly social, Australian parrots ca- the flight calls of migratingbirds is reported.The systemfirst producesa pableof vocal learningthroughout adulthood. These birds readily produce spectrogramusing a DFT. Calls are detectedin the spectrogramusing an short(200 ms), whistled,frequency-modulated contact calls when sepa- ad hoc combinationof local peak-findingand a connectednessmeasure. ratedfrom one another.In this experiment,birds were trainedtwice daily Attributesare extractedboth globally from the call and from a window in 10 rain sessionsto produceor modify contact-call-likevocalizations moved incrementallythrough the call. Decision trees are then used to usingfood reward. Calls were analyzed in real time usingserial Fb-'Fs and determinethe bird species.These decisiontrees are inducedfrom a train- eachproduction was compared to a digitallystored "template." Call pro- ing set using Quialan's (24.5 system [J. R. Quinlan, C4.5: Programsfor ductionswhich exeeetleda predeterminedcriterion of similarity were re- MachineLearning, Morgan Kanffman (1993)]. The systemhas been tested warded,while thosebelow criterion were not. Resultsshow that budgeri- on a set of 138 nocturnalflight calls from nine speciesof birds[W. R. garscan learnto modifythe intensityand spectro-temporal pattern of their Evans,personal communication]. Some calls are faint, and interfering in- species-typicalcalls within several days. Aside from human language, bird sectnoise is presentin others.Tenfold resampling was used to classifythe vocalizationshave provided the only other clear example of learningin the calls unseen.Seventy-eight percent of calls were identifiedcorrectly, 4% acquisitionand maintenance of a vocalrepertoire. While songlearning in incorrectlyand 18% were placedin an "uncertain"category. Neural birdshas led to a numberof importantinsights into the neurobiologyof network-basedclassifiers are commonlyused in this generaldomain and learning,such learning typically occursover a time frame of monthsto wouldlikely producesimilar accuracy, but useof symbolicmachine learn- years.The presentresults demonstrating call learningover a period of ing offerstwo importantadvantages: Training time is linearin the number severaldays more closely parallel the time courseof othermore common of examplesand the resultingclassifier is lessopaque. Both significantly formsof vertebratelearning. [Work supported by NIH GrantsDC00198 ease classifier constmction. andMH00982.] 3370 J. Acoust.Soc. Am., Vol. 97, No.5, Pt.2, May1995 129thMeeting: Acoustical Society of America 3370 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 3:15-3:30 Break evolvedan oticorgan for bothequilibrium and vibration and each function was not separateduntil jawed vertebrates.In the primitiveforms as in 3:30 living lampreys,the brainmust inhibit the ear functionwhen detection of movementand gravity is needed. 4pAB7. Detection of sinusoidalspectral envelopesby budgerigars (Melopsittacusundulatus). SatoshiAmagai, Robert J. Dooling,Tracy L. Kidd (Psych.Dept., Univ. of Mary]and,College Park, MD 20742),and 4:15 ShihabShamma (Univ. of Maryland,College Park. MD 20742) 4pAB10.Dynamic model of the goldfishperipheral auditory system. Previouspsychoacoustic measures of bothcritical ratios and critical JamesJ. Finneranand Mardi C. Hastings (Dept.of Mech. Eng.,Ohio bandsin budgerigarsindicate that the size of the auditoryfilters around State Univ., 206 W. 18th Ave., Columbus,OH 43210) 2-4 kHz approachor areeven smaller than those of humans.Accordingly, budgerigarsshould excel at spectraldiscrimination tasks involving chan- In this study,a dynamic,lumped parameter mathematical model was nels around3 kHz. This study examinedthe ability of budgerigarsto developedfor the peripheralauditory system of the goldfish(Carassius discriminatespectrally rich soundsby usingrippled noise stimuli. Three auratus).This modelexpands upon and couplesexisting models for the budgerigarswere trainedin a repeatingbackground procedure using oper- swimbladder(anterior chamber) and saccularotolith by includingthe ant conditioningto discriminatebetween a complexstimulus with a flat swimbladdertunlea interna and tunlea externa, along with the Weberian spectrumand one that had a sinusoidalripple imposedon its spectrum. apparatus.The viscoe]asticproperties of the tunicaexterna are basedon Each stimuluswas composedof 201 spectra]components logarithmically datafrom Alexander[J. Exp. Biol. 38, 747-757 (1961)].Model predic- spacedfrom 500 Hz to 10 kHz, 100 ms in durationand sampled at40 kHz. tions correlate well with experimentaldata for swimbladderresonance Ripple frequenciesbetween 0.5 and 12 cycles/octwere testedusing ripple frequencyand dampingand with audiogramsobtained from behavioral amplitudesteps of 1/2 to 2 dB. Overall levelsof the stimuliwere varied conditioningexperiments. Model resultsindicate that the WeberJanappa- randomlyfrom 55 dB to 65 dB SPL to remove intensitycues. Ripple ratus has a major affect on auditorysensitivity throughout the audible amplitudedetection thresholds for budgerigarswere similar to thosemea- frequencyrange of the goldfish.In addition,specific phase relationships suredfor humanswith budgerigarsslightly better at higherripple frequen- between the WeberJan,direct, and indirect contributionsto saccularoto]ith cies.[Work supported by NIH GrantsDC00198 and MH00982.] motionare observedfor changingsource location. [Work supportedby ONR Grant No. N00014-94-1-0337.] 3:45 4pAB8. The use of very low and very high frequencies in the 4:30 developmentof an acousticaldeterrent for bird-aircraft collisions. M. Lenhardt,A. Ochs (Biomed.Eng. Prog., Virginia Commonwealth 4pABll. A computer model for simulation of undersea noise from Univ., Richmond,VA 23298-0168), J. Genova,N. Castiglia (Raven, marine mammals. Thomas J. Hayward and Richard M. Heitmeyer Inc.,Alexandria, VA 22312),and M. Kelley (Wright-PattersonAFB, OH (NavalRes. Lab., Washington, DC 20375-5350) 45433) A computermodel for the simulationof the spatialand temporaldis- Bird strikeshave becomean increasingproblem at commercialand tributionof acousticsignals generated by marinemammals is presented. militaryairports. With thedemand for reducedaircraft noise and increased The modelincorporates information from existingreferences on the geo- speed,birds are presentedwith reducedauditory cues and lessreaction graphicdistribution of marine mammal species.Spatial distributionsof time when confrontedwith planes.The major drawback to the use of individualsof eachspecies that may be presentat a siteare generatedusing acousticdeterrents is the rapid habituation.Caged sparrowhawksreadily a randompoint process model that incorporatesa statisticalrepresentation detectedsignals between 5 and 40 Hz with thresholdsof detectability of the spatialclustering characteristics of each species.Individual vocal- rangingfrom 76 to 64 dB SPL. No flying inducedstartles were noted, izations for each speciesare simulatedby randomly selectingsampled althoughthe birds did try to localize the source.Habituation to low- acousticsource signaturesfrom either the Woods Hole Oceanographic frequencystimuli occurredwith as little as three presentations.Free- Institution's SOUND database or from the NRL Dual Use Acoustics Cen- ranginggeese were presentedwith the samefrequencies as substratevi- ter (DUAC) database.The acousticsource signatures are generatedin brationalong with soundpressure stimulation. In a limitedsample (three randomtime patternsthat emulateknown vocalization repetition charac- geese)avoidance was noted.The applicationof low-frequencysound as teristicsfor each species.Sound propagation effects are incorporatedby substratevibration on runwaysis promising.Alternatively, microwaves generatingacoustic transfer functions using propagation models appropri- producean auditorystimulus to the ear thatcan be alteredby changesin ateto the frequencyband of eachacoustic signature. The potentialuse of frequency,pulse width, and overallpower. Pulsed microwaves or micro- the model in the validationof marinemammal acoustic survey techniques wavesmodulated by 1ow4frequencysound are potentialsources alerting is discussed.[Work supported by ONR.] birdsfrom a flying planealready carrying navigation radar. 4:00 4:45 4pAB9. Low-frequencyauditory behavior in sea lampreys, primitive 4pAB12. Study of sound transmissionin various types of stored fish,and marineturtles. M.L. Lenhardt(Biomed. Eng. Prog., Virginia grain for acoustic detection of insects. Robert Hickling, Wei Wei CommonwealthUniv., Richmond,VA 23298-0168and VirginiaInst. of (Natl.Ctr. for Phys.Acoust., Univ. of Mississippi,University, MS 38677), Marine Sci., GloucesterPoint, VA 23062) and DavidW. Hagstrum (U.S. GrainMarketing Res. Lab., Manhattan, KS 66502) Sea lampreys(Petromyzon marinus) are one of only two speciesof livingjawless fish. The brainsand ears of lampreysare remarkably similar In detectinginsect infestations in bulk-storedgrain usingan array of to that of fossilOstracod•rms, a groupof fish thatexisted over 500 mil- acousticsensors, it is importantto knowthe range of soundtransmission in lions yearsago. Jawedfish are derivedfrom jawless fish which in turn grain.Preliminary tests [R. Hicklingand W. Wei,Appl. Acoust. 44 (1995)] radiatedinto primitive bony fish as gars (Lepisosteus) and teleosts and into have shownthat grain can be highly absorbing,depending on frequency, the line leadingto developmentof tetrapods.Marine turtles (Caretta c. and this may limit the rangeat which insectscan be detected.Tests were caretta;Lepidochelys kempi) are consideredprimitive in that they share conductedwith six differenttypes of grain: hard and soft wheat,brown many characteristicswith stem reptilian stock from which birds and mam- rice, soybeans, corn, and sorghum. The results were analyzed using sound- malsalso radiated. The threespecies responded behaviorally and electro- transmissiontheory in porousmedia. Transmissioncharacteristics were physiologicallyto very low frequenciesin a similarfashion despite their determinedand related to grainsize and shape. Tests were conducted of the obviousmorphological differences. All appearto sharean abilityto detect effect of grain depth.Data analysisprovides a measureof the average substratevibrations, suggesting that the primitivevertebrate ear wasalso a spacingbetween grains. The relationof grain spacingto insectsize is low-frequencyvibration sensor. It is hypothesizedthat the firstvertebrates discussed. 3371 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3371 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp FRIDAY AFTERNOON,2 JUNE 1995 MEETING ROOM 2, 1:00TO 5:35 P.M. Session4pEA EngineeringAcoustics: Laboratory and IndustrialApplications of Ultrasound GeraldV. Blessing,Chair NationalInstitute of Standardsand Technology, Sound Building, Room A147, Gaithersburg, Maryland 20899-0001 Chair's Introduction--l:00 Invited Papers 1:05 4pEA1. Applicationof Green'sfunction modeling to ultrasonicprobing of a planar interface. NelsonN. Hsu (NIST, Gaithersburg,MD 20899) Theuse of plane-waveultrasound to probeinterface properties based on angular spectrum analyses is commonin thenondestruc- tivetesting of materials.Space-time domain Green's function modeling is analternative approach to frequencydomain modeling. it is bettersuited for theimplementation of short duration pulses, small aperture transducers, and time-resolved pulse-echo methods. However,a computation based on the Green's function, though conceptually simple, is moreinvolved than a computationbased on the modelof a planewave of fixedfrequency. Recently, an explicitGreen's function for layeredmedia has been derived. Efficient computerprograms have also been developed for caseswhich can be easily tested experimentally and have immediate applications. Asexamples, comparison results between theory and experiment are reported here for three test configurations: (1) a solidplate on a half-spacewith different interface conditions, with a pointstep-function source and a pointdetector located on top of theplate; (2) a liquid/solidinterface, with both the point source and point detector in theliquid; and (3) a linefocus transducer probing a liquid/solid interface.Practical applications to laser ultrasound, simulated acoustic emission, and the acoustic microscope are illustrated. 1:30 4pEA2.Laser ultrasonic monitoring of steelmicrostructure at elevated temperatures. James B. Spicer(Dept. of Mater.Sci. and Eng.,Johns Hopkins Univ., Rm. 102 MarylandHall, Baltimore,MD 21218) Laserultrasonics asa remote,noncontacting ultrasonic testing method has been used extensively for materialscharacterization. However,the unique character of thelaser source has not been exploited fully. This work on steel at elevated temperatures hasmade useof relationships which exist for the thermoelastic lasersource inmonitoring microstructural changes insteel. Ultrasonic monitoring of microstructuralevolution in solidsis performedby makingmeasurements of ultrasonic velocity and attenuation. At elevated temperatures,both the ultrasonicvelocity and the attenuationare affectedindependently of the materialmicrostructure. Thermal expansionof the sample complicates thedetermination of velocity from ultrasonic data since an independent measurement of sample lengthis needed.Contacting transducers allow only intermittent determination of velocity and attenuation since continuous contact mightadversely affect either the transducer or thematerial. In thisstudy, the laser-ultrasonic source characteristics are used to address theseissues related to thetesting of materialsat elevatedtemperatures. Results obtained for the testing of austenitieand martensitie stainlesssteels to temperaturesin excess of 1273K indicatethat characteristic microstructural changes may be detected by analysis of thelaser ultrasonic data. This analysis permits real-time, continuous monitoring of microstructuralevolution. 1:55 4pEA3.Ultrasonic resonance techniques for materialscharacterization and external stress measurement in cylinders and spheres.Ward Johnson and G. A. Alers (NIST,MS 853, 325 Broadway,Boulder, CO 80303) Severalapplications have been explored for ultrasonicresonance measurements using electromagnetic-acoustic transduction on cylindersand spheres. Since the transduction isnoncontacting, acoustic velocities and damping can be determined with great accuracy, andsmall changes in relatedmaterial properties or the sample environment can be detected. The resonant frequencies of certain "axial-shear"modes in induction-hardenedsteelrods have been found to behighly correlated with case depth, providing a nonde- structivemeasure of depthcomparable in accuracy todestructive tests. Applied stress on an aluminum cylinder has been measured with automatictemperature compensation using the resonant frequencies of an axial-shear mode and a torsionalmode, thus demonstrating thebasis for anacoustic load cell Elasticanisotropy in aluminum has been measured from the relative frequency splitting of axial-shearmodes that would be degenerate in isotropic material. Also, electromagnetic-acoustic transduction hasbeen incorporated in a systemused to obtain basic data on the elastic constants and damping of metallicspheres at elevated temperatures. 3372 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt.2, May1995 129thMeeting: Acoustical Society of America 3372 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp ContributedPapers 2:20 accountfor the effectsof particlesize, shapefactor, orientation, as well as concentrationand the soundfrequency. Theoretical predictions of sound 4pEA4. Ultrasonic evaluation of dynamic strain, crack nucleation, speedand attenuation coefficient spectra are comparedwith severalavail- and growth. D. Hazony,G. Welsch,S. Hailu (CaseWestern Reserve ableexperimental measurements ona varietyof colloidsincluding aqueous Univ., Cleveland,OH 44106), and G. Halford (NASA LewisRes. Ctr., suspensionsof polystyrenelatex, TiO2 or kaolin pigment,as well as a Cleveland, OH 44135) toluenein wateremulsion and an oleicacid in nitrogenaerosol. The UCPC The methodproposed is a further developmentof an earlier work approachcan successfullypredict the attenuationspectra of concentrated describedby Hazonyet al. ["Ultrasonicmonitoring of tensile,fatigue, or colloidscovering a wide range of relative magnitudesof viscousversus creepspecimens in situ," J. Acoust.Soc. Am. 93, 2279(A) (1993)]. Two thermalcontributions. Its applicationsfor particlesize and shapecharac- transducersare imbeddedat the front and back faces of the specimens terization will be discussed. alongthe principalaxis. These transmit and receive arbitrarily sharp stress 3:05 pulsesthat probeboth the volumeand the surfaceof the specimen.The respectivetimes of flight are sufficientfor the monitoringof longitudinal 4pEA7. Liquid-borne sub-micron particle detection through acoustic andtransversal strains. Moreover, intensity tracking of the variousreceived coaxing. Sameer I. Madanshetty (Aerosp. and Mech. Eng., Boston acousticsignals also serveswell for monitoringonset and growth of Univ., ll0 CummingtonSt., Boston,MA 02215) cracks.Sensitivity and calibration issues will be discussedand experimen- A novelapproach to the detectionof liquid-bornesubmicron particles tal dataon high-strengthlow-alloy steel and other alloy specimens will be in ultracleanliquids (used in semiconductormanufacture) is described.The presented.The methodlends itself to highprecision measurements of ma- key conceptis to coaxthe submicronparticles to softcavitate and to detect terialdeformation and damage and may be usedat hightemperatures and in aggressiveenvironments. [Work supported by ONR andTecSonics, Inc. the ensuingtransient bubble activity acoustically rather than the particle of Twinsburg,Ohio.] itself.The method,therefore, relies on facilitatingacoustic microcavitation throughacoustic coaxing. Liquid-borne microparticles do not, ordinarily, causeany cavitationwhen exposed to strongsound fields (of I MHz). If, 2:35 however,a very weak, high-frequencyauxiliary acoustic field (e.g., 30 MHz) is addedto this soundfield, cavitationby the microparticlesis 4pEA5. Effect of particle shape on viscousattenuation of ultrasound readily facilitated.This techniqueof facilitating cavitation is termed in concentratedclay suspensions. Wei Han and Hemant P. Pendse "acousticcoaxing." Results of preliminaryexperiments indicate that even (Dept. of Chem. Eng., 5737 JennessHall, Univ. of Maine, Orono,ME smooth sphericalmicroparticles can be coaxed to cause cavitation.An 04469-5737) explanationof the "acousticcoaxing effect" is offered.This novelmethod basedon the acousticcoaxing of microcavitationpromises to be a good Acousticwave propagationin concentratedsuspensions is analyzed basisfor an on-line, real-timemonitor of liquid-bornesubmicronic par- usinga modifiedcoupled-phase modeling approach. The particle,size, ticulatepresence. This methodis not limited to small sensingvolumes, shape,and orientation are taken into account for estimationof viscousdrag and, unlike optical methods,it has an intrinsic,location-specific, signal coefficientof spheroidparticles over wide ranges of frequencyand particle enhancementat the sourceparticle. concentration. The study deals with frequency-dependentand concentration-dependentultrasound attenuation coefficient of clay suspen- 3:20 sions,with particularattention to the effect of particle size and shape distributions.For clay suspensions,the majorloss of acousticenergy re- 4pEA8. Investigation of accuracy of sound-speedmeasurements in sultsfrom the viscousdissipation arising from the relativeparticle-fluid solids: A novel method. Thomas M. Proctor (T-PROsic, 22901 Old motion.Predicted results of sound-speedand attenuationcoefficient based HundredRd., Barnesville,MD 20838) on considerationof particleshape factors agree well with the measure- Speedof soundin solidshas been measured by a numberof different mentsavailable in literaturefor frequenciesof 0.10-5.0 MHz and solid techniquesover the past5 decades.Unfortunately, consistent repeatability concentrationsup to 40 vol%. Experimentalresults of attenuationspectra andaccuracy have been a rareoccurrence. Many error-producingproblems of plate-shapedkaolin clay slurtieswith solidconcentrations of 0.6 to 16.9 of a fundamentalnature have kept this experimental finding suspect at best. vol% over 3 to 60 MHz axeobtained using a newlydeveloped Acousto- In liquids,the definition,dl/dt, for speedof soundcan be usedto check Phor System8000. Theseattenuation spectra are interpretedin termsof the accuracyof the method but, for solids, such incrementalchanges in realisticparticle size and shape distributions. The effectsof nonsphericity path length are not possible.In the case of a plate, a combinationof becomedominant as particleconcentrations and operatingfrequencies are modificationsto the procedurefor the normal on-axis-planewave experi- increased.Realistic size-dependent shape factors are shownto explainthe ment are possible.Over the past 15 years,a numberof improvementsand measuredspectra. innovationshave enhancedthe field of acousticemission. The develop- ment of a point contactreceiving transducer and a repetitiveimpulsive point sourcein conjunctionwith developedGreen's function theory for the 2:50 plategeometry have allowed for a new way of doingthe ultrasonicveloc- 4pEA6. Unified coupled-phaseformulation for estimating complex ity measurement.This new approachwill be discussedand errorproblems wave-number spectra associated with ultrasound propagation inherentin this techniquewill be examined.Results of changein length through concentrated colloidal dispersions. Hemant P. Pendse and versuschange in time of flight will be analyzed.[Work performedby Wei Han (Dept. of Chem. Eng., 5737 JennessHall, Univ. of Maine, contractto NIST] Orono, ME 04469-5737) 3:35 The unifiedcoupled phase continuum (UCPC) approachis utilizedto 4pEA9. Determination of the elastic properties of composite plates analyze sound propagationthrough colloidal dispersionsconsisting of usinggas-coupled ultrasorties. MichaelJ. Anderson (Dept. of Mech. solid particlesor liquid dropletssuspended in a fluid. Attentionis focused Eng., Univ. of Idaho, Moscow, ID 83843-1030), ChristopherM. on the caseof submicronparticles at moderateto high (5% to 50%) vol- Fortunko (NIST, Boulder. CO 80303). and Edwin M Odom (Univ. of ume fractions under ultrasonic frequencies. The governing equations in- Idaho, Moscow, ID) volve equationsof state,continuity, momentum, and energyfor the dis- continuousand continuousphases, respectively. The viscous(thermal) A nonintrusivetechnique has been developed for measurementof the couplingbetween the two phasesis accountedthrough matching terms in elastic toodull of reinforcedpolymer compositeplates. Two ultrasonic theequations of momentum(energy) formulated separately for eachphase. transducersplaced in a transmissionconfiguration use air as the coupling Expressionsfor the viscousand thermalcoupling coefficients explicitly mediumto exciteA0 Lamb wavesin the plate sample.The phasespeed of 3373 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3373 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp theplate waves at a givenfrequency is inferredfrom theangle of incidence 4:35 for maximumtransmission. Use of a low-impedancecouplant gives sev- 4pEAl3. Effects of structure •nsitivity of linear and nonlinear eral advantagesbeyond the nonintrusivenature of the technique.First, the elastic toodull in built-of-eontact systems. V. Yu. Zaitsev (Inst. of influenceof the gasmedium is entirelydecoupled from the determination Appi. Phys.,46 Uljanovastr., Nizhny Novgorod 603600, Russia) of stiffnessmoduli. Second,a low-impedancecouplant gives a high- qualityfactor, which enhances the potentialprecision of thetechnique. Gas Acousticalproperties of built-of-contactsystems are ratherinteresting coupledmeasurements of stiffnesstoodull on unidirectionailyreinforced both from the viewpointof generalphysical acoustics and appliedprob- gmphitedepoxyand glass/epoxy plates of thicknessin Ihe range• 1-6 mm lems.Such structures can oftendemonstrate rather unusual acoustic prop- arepresented. Plate waves were excitedover the frequencyrange 100-200 eftties(in thissense they are similar to sucha popularobject in acousticsas kHz. Stiffnessmoduli Ell, E:•2,Gi2 , andPoisson's ratio v23(fibers in the bubblyliquid). On the otherhand, built-of-contact systems correspond to "1" direction)were obtainedfrom the phase-speed/frequencydata using real physicalstructures, e.g., grainymedia and rough contacting interfaces. leastsquares. Properties determined with the gascoupled technique are Manifestationsof their structuralchanges in linear and nonlinearacoustic comparedwith staticmeasurements, and with modelpredictions based propertiesare importantfor the creationof new methodsof acoustical uponthe propertiesof theconstituents and fiher-volume ratio. diagnostics.The resultsof numericalsimulation of nonlinearharmonic generationunder the actionof an externalsinusoidal drive in a model 3:50 built-of-contactsystem with differentinitial compressionis presented.The modelhas allowed experimental explanation of observed"unusual" non- 4pEA10. The ultrasonicreflection from a fiat-bottom hole. Martin linearelastic properties of real grainymaterials, which cannot be explained ManIcy (SoundBldg., Rm. A-147, NIST, Gaithersburg, MD 20899) by known theoreticalmodels, which do not take into accountnonideality of packing,i.e., the presenceof intergraincontacts with significantlydif- The referencefor calibrationof ultrasonicmeasuring equipment used ferentinitial compression. It wasrevealed that higher-order elastic param- to detect flaws in metal is the reflection from a set of fiat-bottom holes in eters are much more sensitiveto the material structurechanges than the metalblocks. Early experimental observation as well as an earlyanalysis liner modulus.This fact is rather encouragingfor the creationof new usinga far-fieldassumption suggested that the responseshould vary lin- nonlinearacoustic structure diagnostics methods. early with the areaof the hole.Recently, the validity of this linearresult hasbeen called into question by newanalyses as well asexperiment. This paperpresents a new analysisof the reflectedsignal and evaluatesthe 4:50 block set which is usedfor ASTM recommendedpractice E-127 in light of this analysis. 4pEA14. Nonlinear combinational sound scattering by discontinuity-like defects in solids and its possible usage for crack diagnostics.I. Yu. Belyaevaand V. Yu. Zaitsev (Inst.of Appi. Phys.,46 4:05 Uljanovastr., Nizhny Novgorod,603600, Russia) 4pEAll. Lamb wave measurementsfor rapid monitoring of sheet One of Ihe importantproblems in structuralcontrol of solids is the metal. GeorgeA. Alers (NIST, MS 853, 325 Broadway,Boulder, CO problemof discontinuity-likedefects diagnostics. The main drawbackof 80303) conventionallinear diagnosticmethods is the complicmeddifferentiation Lambwaves represent a very naturalchoice of interrogatingenergy for betweena weak "useful"signal originated due to a crackand the waves problemsinvolving ultrasonic inspection of sheetand plate shaped mate- scatteredby otherinhomogeneities of the material,which are not interest- rials.They have not enjoyed wide use in nondestructiveevaluation because ing from the viewpointof flaw detection.In view of this problem,new their excitationand detectionby piezoelectrictransducers require special acousticdiagnostic methods based on measuringnonlinear acoustic char- mechanicalsupports and corrections for the acousticloading of the sheet acteristicshave recently begun to attractthe attentionof researchers.The by the couplingmedium must be made.By usingproperly designed elec- effect of acousticwaves scattering nonlinearly from a thin discontinuity- tromagneticacoustic transducers (EMATs), the transducersupports can be like defectin a solid is analyzed.The defectis consideredas the interface simplified,corrections for leakywaves can be eliminated, and veryspecific betweentwo surfacescovered with bulgescharacterized by differentinitial modescan be used to optimize a particularinspection process. Several deformation.It is shownthat the nonlinearscattering into combinational- examplesof usingspecial Lamb wave modesto inspectpipes and tubesin frequencywaves is much more sensitiveto the loadingof the interface industrialenvironments will be presented,and their use for materialschar- contactscompared with the scatteringinto the wave of fundamentalfre- acterizationin ferromagneticmetals will be emphasized. quency.The observationof nonlinearscattering by crack-typedefects shouldallow one to distinguishcracks from other scatterersand can be usedfor creationof new methodsof crackdetection and positioning. 4:20 4pEAl2. Ultrasonic power output measurementby pulsed radiation 5:05 pressure. StevenE. Fick (NIST, Gaithersburg,MD 20899) 4pEAl5. Theoretical analysis of dynamic characteristics of Direct measurementsof time-averagespaticily integrated output power piezoceramic polymer composites with 2-2 connectivity. Q.M. radiatedinto reflectionlesswater loadscan be made with high accuracyby Zhang and XuecangGeng (IntercoliegeMater. Res. Lab., Penn State exploitingthe radiationpressure which causesan absorptivetarget inter- Univ., UniversityPark, PA 16802) ceptingthe entiretyof an ultrasoundbeam to experiencea force propor- tional to the total beampower, which, in turn, is readily determinableas A dynamicmodel of piezoceramicpolymer composites with 2-2 con- accurately as the racliauon force can be measured in isolation [rom con- nectivity is presented.It can be usedto evaluatethe dispersioncurves for foundingforces arising from such effects as buoyancy, surface tension, and the thicknessresonance and the stopband edge resonance, the effective vibration.A radiationforce balance (RFB) constructedat NBS in 1974 is velocity of the longitudinalwave, as well as the distributionsof strain, the first and only RFB known to be designedto employ simultaneous stress,and the electricfield in a composite.Based on theseresults, the mechanicaland electricalsignal processing based on temporalmodulation electromechanicalcoupling factors are determined using two different of the incidentultrasound at a frequencywell abovethose characteristic of methodsaccording to the IEEE recommendation.It is shown that the confoundingphenomena. Equipped with purpose-builtelectronics, the thicknessmode coupling factor k, obtained from the difference of the RFB is operatedby manually equalizingthe radiation force and a coun- effectivelongitudinal velocities at the constantelectric field and constam terforcegenerated by an actuatorcalibrated against reference masses using electricdisplacement is in goodagreement with theexperimental values. It dc currentas the transfervariable. Improvements made to the RFB during is also shownthat, due to the compositestructure, the piezoelectricshear its one overhaul in 1988 have nearly halved its overall measurements coefficienle•s has a strongeffect on both the effective velocity of the uncertainty,and extendedits capabilitiesto includemeasuring the output longitudinalwave u D andk• evenat the limit where the composite thick- of ultrasonicsystems with arbitrarypulse waveforms. nessis muchlarger than the period. On theother hand, k• calculatedfrom 3374 d. Acoust.Soc. Am., VoL97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3374 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp the energyconsideration is muchhigher than the experimentalvalues and studyinvestigate the effectof the lengthon the acousticattenuation per- cannotaccount correctly for the effectof e•5 on kt . From the model,the formanceof concentricexpansion chambers. Three approachesare em- evolutionof thethickness mode and the stop band edge resonance with the ployed here to determinethe transmissionloss: (1) a two-dimensional, thicknessof a compositeand the modescoupling between the two canalso axisymmetricanalytical solution; (2) a three-dimensionalcomputational be elucidated. solutionbased on the boundary element method; and (3) experimentson an 5:20 extendedimpedance tube setupwith nine expansionchambers fabricated with the fixed inlet and outletduct, and chamberdiameters, and varying 4pEA16. The effect of length on the acoustic attenuation chamberlength to diameterratios from 1/d=0.2-3.5. The resultsfrom all performance of concentric expansion chambers. A. Selamet and P. threeapproaches are shownto agreewell. The effect of multidimensional M. Radavich (Dept. of Mech. Eng. and Appl. Mech., 120 W. E. Lay propagationis discussedin comparisonwith the classicaltreatment for the Automotive Lab., Univ. of Mich., Ann Arbor, MI 48109-2121) breakdownof planar waves. The study also providesa simple relation Following an earlier analytical and computationalwork of Sahas- betweenthe l/d ratio of the expansionchamber and the numberof repeat- rabudheet al. [NoiseControl Eng. J. 38(1), 27-38 (1992)],the present ing attenuationdomes prior to the dominationof higher-ordermodes. FRIDAY AFTERNOON, 2 JUNE 1995 AUDITORIUM, 1:00 TO 5:00 P.M. Session4pPA Physical Acoustics:Nonlinear Acoustics Murray S. Korman, Chair Departmentof Physics,U.S. Naval Academy,Annapolis, Maryland 21402 ContributedPapers 1:00 Copenhagen(IPC Scienceand Technology, London, 1974), or interaction withreal sources [P. I. Westervelt,Virtual Sources in thePresence of Real 4pPAI. The Tait equationand its connectionwith B/A: An historical Sourcesin NonlinearAcoustics, edited by T. G. Muir (Proc.of Univ. of note. RobertT. Bcyer (Dept. of Phys.,Brown Univ., Providence,RI Texasat AustinConference, Nov. 1969)]. 01912) In the 1880s,the Scottishphysicist R G. Tait set up an empirical 1:30 equationto tit pressure-volumedata for freshand salt water, gathered on a researchexpedition of theH. M. S. Challenger["Physics and Chemistry" 4pPA3. Scattering of sound by sound within the interaction zone: of theVoyage ofH. M. S. Challenger,Vol. II, partIV (1888)].This equa- Approximatesolutions. PeterJ. Westervelt (Dept. of Phys.,Brown tion,together with two or threevariants of it, wasthe startingpoint of a Univ., Box 1843, Providence,RI 02912) numberof researchesover the next 70 years.In the 1950s,it wasput to use The exact second-order transient solution to the interaction of an arbi- in still anotherform, and became the ancestor of thequadratic relationship trarywave with a planewave is givenby Westervelt[P. J. Westervelt,J. of pressureand densityused in nonlinearacoustics. The historyof this Acoust.Soc. Am. 96, 3320 (1994)]. Let the arbitrary wave be X(xø-•.r), developmentand the connectionbetween the Tait equationand the ratio a planewave traveling in the•h direction.In thiscase o-= (1 -fl. •n) lX and B/A is set forth. the solution to Eckart's equation becomes psc•= E•2 +(I-fi4h)-•(A+2fi4h)=cos0V2•, whichis identicalto Eq. (10) of 1:15 Westervelt[R J. Westervelt,J. Acoust.Soc. Am. 29, 934 (1957)]provided thesubstitutions •p•= «(w}w2)-•W•_ and fi4h=cos 0 are made. It is as- 4pPA2. General proof of the nonscatteringof sound by sound in the sertedthat this exact solution servesas an approximatesolution to the losslessdispersionless case. PeterJ. Westervelt (Dept.of Phys.,Brown far-fieldinteraction of arbitrarysources. This is doneby allowingfn andfi Univ., Box 1843, Providence,RI 02912) to be spacedependent. As an example,the exactsolution for the cardioid waveX=(4•rr)-l[fi4h(G,o+Gr •)-G.0 ] interactionswith a plane Introducingthe variable rr: p•c•q- L q-A V intoEq. (14) of Westervelt waveis obtainedfrom rr=-(4rrr)-IG.0, whereG=G(xø-r) and [P. J. Westervelt,J. Acoust. Soc. Am. 29, 200 (1957)],two equivalent ß =rr •. In thefar field of thecardioid source, rr=(1-fi-•)-iX, asin the dissipationlesswave equations are obtained for the scattered variable p•c02: planewave-plane wave interaction,thus demonstrating the assertion. Eq. (1) is El2[•r + 2(•).00] = FV,00 and Eq. (2) is U]2[z--A(q•).00]=FT.00in whichff12•=L and F=-(2+A). Outside theregion of interaction•r=p•cg so the source for psc•can be either 1:45 FV.oo orFT.o 0 andsince, in general,T•: V, p•cgmust be zero (except for 4pPA4. Nonlinear bubble oscillationsand Bjerknes forces. Sean M. unidirectional waves when T= V in which case the well-known solution is Cotdry (Dept. of Phys.,Univ. of Mississippi,University, MS 38677), still restrictedto the interactionzone). As an example,consider two col- LawrenceA. Crum, and RonaldA. Roy (Appl. Phys.Lab., Seattle,WA lidingwaves for which the interactionenergies satisfy Ti2= - Vi2 requir- 98105) ingpsCo 2 from Eq. (1) to be the negativeof thatfrom Eq. (2) which demandsthat p•c 6= 0. Wtthmthe interactionregion the solutionto either The acousticlevitation of bubblesin standingwaves has been consid- equation is Psc•=(A-2)(•b*•b ,0o+qb qb*.0o-2qb*,0qb,0), where ered by many authors.Calculations of the equilibriumlevitation position •p=,;b*+•b-the sum of rightand left travelingwaves. The scatteredpres- havefollowed the exampleof Eller [A. Eller, J. Acoust.Soc. Am. 43, surep• = p•c•+ A V. Forscattering to occur outside the interaction region, 170-171(1968)] by consideri..ng linear radial pulsations whose amplitude theremust exist losses,as witnessedin the parametricarray, or dispersion is given by a linearizedRayleigh-Plesset equation. This procedurebegins [see,e.g., P. J. Westervelt,"Scatteringof Sound by Sound,"in FiniteAm- to fail as the bubble startsbehaving in a nonlinearfashion. For bubbles plitude WaveEffects in Fluids, edited by L. Bj6m6, Proc. 1973 Symp. experiencingnonlinear behavior, the radiationpressure (primary Bjerknes 3375 d. Acoust. Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3375 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp fome)must be numericallycalculated from the productof the instanta- differential-integralequation for nonlinearwave propagation when diffu- neousbubble volume and the pressuregradient of the soundfield. Bubbles sivemotions can be neglected.The processes of dissipation (e.g., viscous smallerthan resonance size are normally 9ttracted tothe pressure antinode, andthermal), chemical relaxation, and nonlinear equation of stateresponse butwhen nonlinear effects are considered, thebubbles can be repulsed by influencethe waveprofile. Approximations, such as low-frequencyand the pressureantinode for driving pressuresabove a certainthreshold am- high-frequencyexpansions [J.Engelbrecht, Wave Motion 1, 65 (1979)]are plitude.Results of our calculationswill be presentedalong with the im- examined.The low-frequencyresults in the classicalBurgers' equation. plicationsfor singlebubble sonoluminescence. [Work supported by the Applicationswith calculationsuse informationavailable in the literature officeof Naval Research.] forocean and electrolytic solution environments. Thecase of slightly in- homogeneousmedia will alsobe discussed. 2:00 2:45-3:00 Break 4pPA5. Nonlinear elastic wave propagationalong free surfacesof a thick plate. M. E Hamilton,Yu. A. ll'inskii, and E. A. Zabolotskaya (Dept.of Mech.Eng., Univ. of Texas,Austin, TX 78712-1063) ß 3:00 Nonlinearelastic wave propagation along free surfacesof a thick iso- 4pPA8. An acoustic device for Prandtl number measurements in tropicplate is investigatedtheoretically. The finite thicknessof the plate gases. KeithA. Gillis,Michael R. Moldover (NIST, Thermophys.Div., introducesdispersion. In the linear approximationthe solutionis a super- Bldg. 221/Rm. ALII, Gaithersburg,MD 20899), and JamesB. Mehl positionof symmetricand antisymmetricmodes, and the wave field un- (Univ. of Delaware,Newark, DE 19716-2570) dulatesalong the surfacesof the plate. Nonlinearity is taken into account An acousticmethod is being developedfor measurementsof both the with the Hamiltonianformalism used to model Rayleigh wavesof finite thermaland viscous diffusivities of gasesusing different sets of resonances amplitude[Zabolotskaya, J.Acoust. Soc. Am. 91, 2569-2575 (1992)].The of a singlecavity. The ratio of the diffusivities,i.e., the Prandtlnumber, is resultingcoupled spectral equations were integrated numerically to inves- a key parameterin determiningthe heattransfer from a solidto a moving tigateharmonic generation and waveformdistortion in an initially mono- fluid.Honeycomb inserts placed near the center (z = L/2) of a cylindrical chromaticwave generatedon one side of the plate.Two differentplate cavity(length L) providea largesurface area with minimal blockage of thicknesseswere considered,20 and 100 shear wavelengths.For the longitudinalacoustic flow. Odd-orderlongitudinal modes, which have a thickerplate, and with a shockformation distance much smaller than the velocityantinode at z = L/2, have a strongvmcous interaction with the dispersionlength, the solutionsresemble those for nonlinearRayleigh insert.For even-ordermodes. which have temperature antinodes at z = L/ wavesin a half-space.For the thinnerplate, and with thetwo lengthscales 2. thethermal interaction dominates Measurements of the resonance pa- of thesame order, propagation curves for the second harmonic component rametersof bothtypes of modesare analyzed using a modelwhich enables exhibitthe "growth-decaycycles" that have been measured in experiments the viscousdiffusivity to be determinedfrom the odd modesand the and discussedin a previousarticle [Shull et aL, J. Acoust.Soc. Am. 94, thermaldiffusivity from the even modes.Because the sameinsert is used 418-427 (1993)].[Work supported by NSF, Schlumberger, and the Office for both the even and the odd modes. the ratio of the diffusivities is not of Naval Research.] sensitiveto detailsof the geometryof the insert:thus. the Prandtlnumber canbe determined more accurately than either diffusivity. [Wo•-supported 2:15 by ONR.I 4pPA6. Acoustic streaming at high Reynolds numbers in focused 3:15 soundbeams. M. F. Hamilton,Yu. A. ll'inskii, andE. A. Zabolotskaya (Dept.of Mech.Eng., Univ. of Texas,Austin, TX 78712-1063) 4pPA9.Ab initio calculationsfor helium,acoustics, and metrology. In experimentsreported recently on acousticstreaming in focused Michael R. Moldover (NIST. Thermophys.Div.. Gaithersburg,MD 20899) soundbeams [Starritt et aL, UltrasoundMed. Biol. 15, 363 (1989), and Matsudaet al., Advancesin NonlinearAcoustics: 13th 1SNA, edited by H. Lossy,gas-filled resonators are now beingdeveloped at NIST to mea- Hobaek(World Scientific, Singapore, 1993), pp. 595-600], theReynolds surethe viscousand thermaldiffusivifies of gases.If theseresonators numbersfor the streamingare of order 100.To modelsuch experiments, becomeas well understoodas the low-lossspherical resonators already nonlinearityin the momentumequation for the streamingvelocity should developedat NIST. the uncertaintyin the measuredviscosity of a dilute be takeninto account. Previous comparisons of theorywith measurements gaswill becomeless than 0.1%. possibly limited by thedifficulty of mea- of acousticstreaming in focusedbeams am basedon linearequations for suringthe dimensions of a double-Helmholtzresonator (i.e.. a Greenspan the streamingvelocity, which are normallyvalid only for Stokesflows viscometerlThe accuracyof thedata from the acousticviscometer will be characterizedby Reynoldsnumbers less than unity [Lighthill,J. Sound testedby comparingexperimental results for heliumwith the recentab Vib. 61,391 (1978)].The numericalresults presented here were obtained inttioresult from quantummechanical calculations: r/=119.800_+0.010) with nonlinearinertia terms for the streamingvelocity retained in equa- /•Pa s at 298.15 K. Similarly, the resultsfor the Prandtlobtained from tionsthat describe the paraxialregion of the beam.The primarywave is cylindricalacoustic resonators with insertswill be testedby comparison assumedto be a focusedGaussian beam, with parameters corresponding to withthe ab initio result: Pt= (Cprl/XM) =0.66419. Helium-based gas ther- theexperiments cited above. Inclusion of nonlinearityyields predictions of mometry (both traditional and acoustic• will benefit from the theoretical streamingpatterns that are more localized in thefo4al region, and in closer resultsfor the secondvirial coefficient of helium.Perhaps pressure mea- agreementwith experiment,than predictions based on linearizedequations surementsin the 1- to 10-MParegion could be improvedby combiningthe for the flow.[Work supported by Schlumberger,NSF, and the Office of ab initio results with highly accuratemeagurements of the dielectric con- Naval Research.] stant of helium. 2:30 3:30 4pPA7. Nonlinear waves through multicomponentfluid media with 4pPA10.Recent progress and problemson studyof forcedstanding chemicalreactions. TimothyS. Marguiles (Natl.Ctr. for Phys.Acoust., solironsgenerated in Faraday wave experiment. RongjueWei (Inst. Univ. of Mississippi,Oxford, MS 58677) of Acoust..Nanjing Univ.. Nanjing 210008. People's Republic of China) Finite-amplitudewave propagation has been investigated using balance Fromthe simpleFaraday wave experiment with rectangular tanks of and constitutiveequations derived via continuummixture theory for a variablelength and width. or withinsection of partitions.the standing or multicomponentsystem such that simultaneouschemical reactionscan nonpropagatingsolirons will manifesta numberof interestingnonlinear occur.A multiple-timescale perturbation approach IT. Tanuitiand C.-C. phenomena.These include parameters governing generation. stability, col- Wei, J. Phys.Soc. Jpn. 24 (4), 941 (1968)]was usedto developa lisiondynamics. reflection symmetry, chaotic behaviors. etc.. of one or 3376 J.Acoust. Soc. Am., Vol. 97, No. 5, Pt.2, May1995 129thMeeting: Acoustical Society ofAmerica 3376 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp more soiltons.Some of the not well-solvedproblems of the physicsand Lorentzforces due to the eddycurrents induced in the diskaccelerate the mathematicalformulations will be presented.[A brief summaryof the diskaway from the coil. The diskacceleration produces a shock wave in a workby the NonlinearAcoustics Group I of Nanjing,supported by Chi- liquid-filledcavity. A convergentreflector focuses the waveonto a nozzle. neseNonlinear Sc. Foundation.] The reflectionof the shockwave from the water-air interfaceproduces a discretewater jet. A theoreticalanalysis of theelectrical characteristics of the transduceris presented.A finite-elementpackage was used to optimize 3:45 the convergentreflector. Experimental results from a prototypegenerator 4pPAll. Capillary bridge stability in an acousticstanding wave: aregiven including pressure measurements from a needlehydrophone and Linearized analysisof passivestabilization with radiation pressure. schlierenphotographs of the water jet. [Worksupported by FRD.] PhilipL. Marston (Dept.of Phys.,Washington State Univ., Pullman,WA 99164-2814) A liquid bridgebetween two solid surfaces,known as a capillary bridge,has applications in low gravitysuch as the solidificationof floating 4:30 zones.Long bridgesare naturallyunstable to a symmetricmode where a region adjacentto one end bulgeswhile the oppositeend thins. For a 4pPA14.Coherent enhancement ofreflected signals ina parametric cylindricalbridge of radiusR andlength L, the slendernessS=L/2R has echo-sounder.Dimitri M. Donskoy (DavidsonLab., StevensInst. of a natural(Rayleigh) limit of •r beyondwhich the bridgebreaks. It is Technol.,711 HudsonSt., Hoboken,NJ 07030), AlexanderM. Sutin, proposedhere to stabilizedense bridges at a velocityantinode of a stand- andAndrew I. Potapov (Inst.of Appl. Phys.,Nizhnii Novgorod, Russia) ing acousticwave perpendicular to the bridgeaxis. Let (Pt) denotethe A parametricecho-sounder is usedfor sea sub-bottomprofiling and angularaverage of the radiationpres.sure over the surfaceof a cylindrical target (cables, mines, etc.) finding. It generatesa modulatedhigh- bridge.It is necessaryto selectthe acousticfrequency such that (Pr) frequencysignal (pump signal). Due to the nonlinearityof water,part of increaseswith R so that a bulge is automaticallysqueezed by the increased the pumpenergy is convertedinto a low-frequencywave namedthe sec- radiationpressure. Linearized analysis of the stabilityindicates S may be ondary signal.The high-frequencypump signal reflectsmostly from a extendedbeyond •r: Sm•x depends onq= (R2/'y)d(pr)/dR,where 7 isthe bottomsurface and hashigh signal-to-noiseratio. The low-frequencysec- surfacetension and Stoa• divergesas q approachesunity. The analysis ondarysignal penetrates deeper under the bottomand reflectsfrom sub- Supportsthe possibilityof passiveacoustic stabilization of capillary bottomlayers and buried objects.However, the level of thesereflected breakupin low gravity.The one-dimensionalinviscid slice approximation signalsis low, oftenbelow noise level. In orderto enhancethe signal-to- is usedin theanalysis of axisymmetricdeformations. [Work supported by noiseratio for thesereflected secondary signals, the coherent average tech- NASA.] niquecan be employed with the use of thereflected pump (high-frequency) pulsesas reference signals. The feasibilityof thisapproach is basedon the 4:00 followingconsiderations. (1) The pump and the secondarysignals are alwayscorrelated. (2) Averagefrom onepulse to anotherdoes not depend 4pPA12. Capillary bridge modes driven with modulated acoustic on deviationin distancebetween the transducerand the bottom(due to the radiation pressure. Scot E Morse, David B. Thiessen,and Philip L. pitching,drifting, etc.) becausethe referencesignal (reflected from the Marston (Dept. of Phys., WashingtonState Univ., Pullman, WA bottompump signal) always follows this deviation.(3) The frontof the 99164-2814) pumpsignal is muchsharper as comparedwith the frontof the secondary signal.Therefore coherent averaging of the secondarysignals can be done A liquid bridge betweentwo solid surfacesis known as a capillary precisely.(4) For the "frozen"sub-bottom structure time delaysbetween bridge.In theexperiments to be described,the bridge liquid is a mixtureof the firstreflected signal and the all followingreflected signals are fixed; PDMS with a denseorganic liquid. The bridgehas the samedensity as the thereforethe coherent accumulation will takeplace for all of thesesignals. surroundingwater bath suchthat its equilibriumshape between circular The proposedmethod was proved during feasibility field test performed at postsis a circularcylinder of lengthL andradius R. Low-frequencymodes Barents Sea. of sucha bridgeare knownto exist wheresurface tension provides the restoringforce. Even neglectingviscosity, the modalcharacteristic equa- tion is complicatedby the boundaryconditions. It is demonstratedthat low-frequencymodulation of an ultrasonicstanding wave in the surround. ing bathcan be usedto excitespecific axisymmetric or nonaxisymmetric 4:45 capillarymodes. Coupling to eachmode depends on the locationof the bridgein the standingwave. The couplingis a consequenceof the space- 4pPA15, Nonlinear vibro-acousticmethod for diagnosticsof cracks timemodulation of theradiation pressure as discussed previously for drops in constructionmaterials. Aleksey S. Korotkovand AlexanderM. andbubbles [P. L. Martson,1. Acoust.Soc. Am. 67, 15-26 (1980)].The Sutin (Inst.of Appl.Phys., Russian Academy of Sciences,46 UljanovSt., predicteddecrease of modefrequ•ncy-with increasing slenderness S = L/ 603600Nizhny Novgorod, Russia) 2R is confirmedas is the vanishingof the frequencyof the mostunstable modeas S approaches•'. [Worksupported by NASA.] New methodsfor the diagnosticsof defectsin objectsmade of con- strnctionmaterials, primarily of metals,are proposed. The basicconcept of theproposed methods is simple:Materials containing defects have a much 4:15 largernonlinear response than materials with nodefects. For materialswith integrity,the nonlinearresponses are up to severalorders less as compared 4pPA13. An electromagnetic liquid shock wave generator for the with the case of defectedmaterials with defects.It is noteworthyto stress productionof a pulsedwater jet. BruceJ.P. Mortimer (Schoolof Elec. that these nonlinear effects are noticeable even at small strains far from a Eng.,Cape Technikon, P.O• Box 652, Cape Town, 8000, South Africa) and materialdamage threshold, thus making it ratherattractive for nondestruc- BericW. Skews (Univ. of the Witwatersrand,Johannesburg, 2050, South tive testing.The first experimentswere performedemploying samples Africa) shapedas rods made of steelused for fabricatingparts of nuclearreactors. Waterjets canbe eithercontinuous or pulsed.Pulsed or discretewater Thesamples were exposed to staticstretching in orderto introducedefects. jetshave many advantages over continuous jets in certainapplications. The Acousticfield modulationwas measured by low-frequencyvibrations and productionof discretejets hasmostly been due to a momentumtransfer its increase (more than 30 dB) in stretchedsamples was observed.The froma massimpacting a compressionchamber. In thisstudy the feasibility nonlinearinteraction of the impact-producedvibrations with the acoustic of usinga noveladaptation of an electromagneticsource (EMAS) for the fieldin steelsamples with a crackwas investigated. It wasshown that the productionof a pulsedwater jet is investigated.This device consists of a modulationof soundby suchvibration can be usedfor cracksdetection. high-voltage4-8 F, 20-kV capacitorwhich is dischargedthrough a flat The methodwas alsoused to test a weldedjoint fin a largepipe line for a pancakecoil. An insulatedmetal disk is in closeproximity with the coil. nuclearpower station. 3377 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3377 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp FRIDAY AFTERNOON, 2 JUNE 1995 GRAND BALLROOM CENTRAL, 1:00 TO 5:00 P.M. Session4pPP Psychologicaland PhysiologicalAcoustics: Harvey FletcherMemorial SessionH Jont B. Allen, Cochair AT&T Bell Laboratories,Room 2D-553, 600 MountainAvenue, P.O. Box 636, Murray Hill, New Jersey07974-0636 Roy D. Patterson,Cochair MRCApplied Psychology Unit, 15 Chaucer Road, Cambridge, CB2 2EE United Kingdom Larry E. Humes, Cochair Departmentof Speechand Hearing Science,Indiana University,Bloomington, Indiana 47405 Invited Papers 1:00 4pPPLCochlcar modeling since Fletcher. William M. Siebert'(Res. Lab. of Electron.,Rm. 36r825, MIT, Cambridge,MA 0:2139) In 1951, HarveyFletcher published a comprehensiveanalysis of the macromechanicaldynamic behavior of the cochlearpartition in responseto sound.Although not the first to derive the now-familiarone 1:30 4pPP2.The auditoryfilterbank: Fletcher's functional model of hearing. RoyD. Patterson(MRC Appl.Psych. Unit, 15 Chaucer Rd., CambridgeCB2 2EF, IIK) Fletcher[Rev. Mad. Phys. 12, 47-65 (1940)]summarized his observations onpitch, loudness, and masking in termsof "auditory pattems•spirallines representing the cochlea with shadedregions showing neural responses to sinusolds.The auditoryfilterbank was a setof overlappingauditory patterns spanning the frequencyrange of hearing--aconcept that has served as a functionalmodel of auditoryfrequency analysis ever since. It hasfour main components: thefilter shape, its bandwidth, the distribution of filters across frequency,and the detectioncriterion at the filteroutput. Fletcher identified these components and focused attention on themwith his famous"band-widening" experiment in whicha toneis maskedby a variablewidth noise centered on the tone.The currentpaper reviewsfour areasof researchspawned by the componentsof Fletcber'sfilterbank concept. The researchhas shownthat the band-wideningexperiment is actuallyrather insensitive, and subject to a confoundingwhich led to underestimationof filter bandwidth and overestimationof the detectioncriterion. But the more importantassumptions about filter shapeand distributionwere proven essentiallycorrect. As a result,current, computational, auditory filterbanks are surprisinglysimilar to Fletcber'soriginal conception. 2:00 4pPP3.The excitation-patternmodel according to Fletcher. S•ren Buus (Commun.and Digital SignalProcess. Ctr., Dept. of Elec. and Cornput.Eng. (409 DA), NortheasternUniv., 360 HuntingtonAve., Boston,MA 02115-5096) This talk reviewshow Fletcherused excitation patterns to understandauditory processing. In the 1930's,Fletcher suggested that the relationbetween place of maximalexcitation on the basilarmembrane could be derivedfrom measurementsof criticalbandwidths andfrequency difference limens. He also showed that loudness andmasking were closely related and that loudness foran arbitrary soundcould be calculatedon thebasis of patternsof excitationintegrated along the basilar membrane. Likewise, he suggestedthat discriminationof level differencesbetween sounds could be understoodon the basisof theirexcitation patterns. These concepts remain valid 60 yearslater. 2:30 4pPP4.Fletcher and the powerspectrum model of hearing. RobertP. Carlyon (MRC Appl. Psych.Ilnit, 15 ChaucerRd., CambridgeCB2 2EF, England) Fletcber'sfamous band-widening experiment demonstrated that the maskingof a puretone by a continuousbroadband' t•oise was determinedonly by thosecomponents of the noiseclose to the signalfrequeucy. This formedthe basisof the pervasive"power spectrum"model of hearing,according to whichthe threshold of a signalof a givenfrequency is determinedby theamount of masker energypassing through an audito• filtercentered on thatfrequency. This rigorousprediction has aided the identificationof additional formsof auditoryprocessing, which havebeen revealed by exceptionsto the powerspectrum made/. The interpretationof such 3378 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of Amedca 3378 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp findings,which include CMR, profileanalysis, informational masking, and the overshoot effect, is greatlyfacilitated by theexistence of a "default"model which accounts for a largeamount of otherdata. In additionto reviewingthese developments, new evidence will bepresented demonstrating thatthe shape of a masker'sexcitation pattern can also be affected by the shape of its(temporal') envelope. 2:45 4pPP5. Evaluatinghuman neural tuning curvesfrom a mechanicalmodel of the cochleaby relating them to psychophysicai maskingdata. P.A. Gerbesand J. B. Allen (Acoust.Res. Dept., Rm. 2D553, AT&T Bell Labs,Murray Hill, NJ 07974) Humanneural threshold tuning curves are estimated by scalingthe parameters of Allen's[J. Acoust.Soc. Am. 68, 1660-1670 (1980)]resonant tectorial membrane model of thecat cochlea. A wayto evaluatethe derived tuning curves using psychophysical data is developed,based on a psychophysicaldetection mode] which relates the physiologicaltuning curves to psychophysicalmasking data.A detectioncriterion, defined by a relationshipamong the bandwidth of thefrequency tuning curves, expressed as an equivalent rectangularbandwidth (ERB), the width of theexcitation patterns, expressed as an equivalentrectangular spread (ERS), and the psychophysicalcritical ratio, is exploredand verified using cat data.The detectioncriterion is thenused to testthe derived human curvesby makingpredictions of psychophysicalmasking and comparing the predictions to experimentaldata. The detectionmodel may alsoprovide a deeperunderstanding of the frequencyresolving properties of the cochlea. 3:00-3:15 Break 3:15 4pPP6.Fletcher and loudness. Larry E. Humes(Dept. of Speech& Hear.Sci., Indiana Univ., Bloomington, IN 47405) In thispresentation, some of thepioneering work performed by HarveyFletcher and colleagues on the loudnessof simpleand complexsounds will bereviewed. The focus will beplaced on the model and data presented by Fletcherand Munson [H. Fletcherand W. A. Munson,J. Acoust.Soc. Am. 5, 82-108 (1933)].In thisclassic paper, the authors lay a solidfoundation for the understanding of loudnesswhich remainsremarkably intact today in light of contemporarypsychophysical and physiologicalknowledge. They providethorough descriptions of several loudness phenomena, including loudness growth, tooneural loudness additivity, and binaural loudnesssummation. Among other things, they demonstrate that loudness for a singletone grows as a functionof thecube root of stimulusintensity, that loudness is additive for stimuluscomponents in separate auditory filters or in separateears, and that loudness of partiallymasked stimulus components is also additive once adjustments for partialmasking have been made. Fletcher and colleagueswere also interested in applying their model of loudnessto hearing-impaired listeners. Their prior efforts in thisarea will beupdated by thereview of contemporarydata on loudnessgrowth and summation in thehearing impaired. 3:45 4pPP7.Fletcher's contributions to loudnessmeasurement and theory. RhonaP. Hellman (Aud.Percept. Lab., Northeastern Univ.,360 HuntingtonAve., Boston, MA 02115) Morethan 70 yearsago, Fletcher and his colleagues at BellTelephone Laboratories initiated the first comprehensive investigations of loudness.Fletcher recognized that to improvethe quality and efficiency of speechcommunication systems, one must know how the ultimatereceiver, the human auditory system, processes and perceives sound. In hispioneering loudness studies, Fletcher devised innovativetechniques for themeasurement of loudness, uncovered the key parameters that modify loudness, and developed a model relatingloudness tobasic properties ofthe hearing mechanism. The achievements ofFletcher and his group demonstrated thatloudness measurementscandisclose (1) therelation between the spectral selectivity of hearingand sound intensity, (2) theeffects of masking on loudness,(3) theprinciples of loudnessadditivity, (4) thedependence of loudness on spectralbandwidth, aswell as (5) the functionalintegrity of theauditory system. These seminal discoveries not only inspired subsequent loudness studies, they also provided theempirical and theoretical foundation of contemporary loudness research and models. [Work supported in part by NIH GrantROI DC00084-18.] 4:00 4pPPS.Multichannel auditory perspectives, a historical view of HarveyFletcher's forgotten contributions and their ramifications.Frederick 1.Ampel (Technol. Visions S.A., 9512 W. 93rd St., Overland Park, KS 66212) and TedUzzle (Sound & VideoContractor Magazine, Overland Park, KS 66212) Thehistory of soundtransmission, recording and reproduction, and the number of channelsthose technologies may employ, is complexand convolute& It has proceeded down numerous paths, and found many dead ends. Beginning with the work of Bell, Edison, andClement Ader, the technicalachievements and insightsneeded to producesuccessful and aurallyaccurate reproduction required muchinvention and enormous amounts of insight.How manychannels? Sonic accuracy or artisticeffect? Loudspeakers or head- phones?Live or recorded?When Fletcher began his investigations in 1931, no one knew the answers. Regrettably, his significant contributionshave been either lost to timeor ignored.Without Fletcher much of whatis knowntoday about perception and sound wouldnot have been possible. This paper will examinehis contributions, remind one of theanswers he found, show where they led, and bringthem once again to the forefront. 3379 J. Acoust.Soc. Am., Vol. 97, No.5, Pt. 2, May1995 129thMeeting: Acoustical Society of America 3379 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 4:30 4pPP9.Harvey Fletcherand musicalacoustics. William J. Strong,Irvin G. Bassett (Dept.of Phys.and Astron., Brigham Young Univ., Provo,D-T 84602), and William M. Hartmann (MichiganState Univ., East Lansing,MI 48824) Althoughthe bulk of hiswork was concerned with variousaspects of speechand hearing in communication,Harvey Fletcher had a longtimeinterest in musicalacoustics. This interestis evidencedin his paperson perceptualaspects of musicaltones, which stressed the complexinterdependences of the perceptsof loudness,pitch, and timbre on the physicalparameters of intensity,frequency, and spectrum.However, his activeinvolvement in musicalacoustics research came to fruitiononly after he was releasedfrom other research,administrative, and teachingresponsibilities. In conjunctionwith others,he exploredperceptual aspects of piano,organ, violin, and percussiontones. His approachwas that of analysisof naturaltones, followed by synthesisof thesetones based on the analysisresults. Real and synthetic tones were presented to listenerswho were asked to judge the tones as being real or synthetic.When listenerswere unable to distinguishbetween the two,the synthetictones were considered to containall of theessential ingredients of the real tones.Fletcher's papers in whichthis work wasdescribed will be reviewedand samplesof his real and synthetictones will be presented. FRIDAY AFTERNOON, 2 JUNE 1995 MEETING ROOMS 12, 13, 14, 1:15 TO 2:45 P.M. Session4pSAa Structural Acousticsand Vibration: Radiation Transmissionand Coatings J. Smart Bolton, Chair Purdue University,1077 Ray W. Herrick Laboratories,West Lafayette, Indiana 47907-1077 ContributedPapers 1:15 therebyeliminating the need for far-fieldacoustic sensor(s). The radiation of the structureis estimatedfrom this information,either directly or from 4pSAal. Estimating acousticradiation from a Bernoulli-Euler beam a modelof the radiatingstructure. The directapproach has the advantage using shaped polyvinylidenefluoride film. Brian L. Scott and Scott of not being dependenton the accuracyof any model.A new sensing D. Sommerfeldt(Grad. Prog. in Acoust.and Appl. Res.Lab., PennState strategyis hereinpresented, in bothdirect- and model-basedapproaches, Univ., P.O.Box 30, StateCollege, PA 16804) where the estimationof acousticradiation involves monitoring the strain A numberof methodsexist for determiningfar-field soundradiation field of the structure.Such information is directlygiven by fiber optics from structures.Among such prediction techniques are purelyanalytical sensors,for example,so that significant gain is expectedat thislevel. Two modelsand use of discretesensors placed directly on the structureor in the approachesare presentedusing strain information. The firstformulation is surroundingfluid media. Analytical methods suffer from a lackof abilityto obtainedby integratingby partsthe Rayleigh'sformula. Dependence on model the structurecompletely and adaptto unforeseensystem changes. boundaryconditions then appearsand has to he dealt with. The second Discretesensors on the beammay requirea largenumber of transducersto formulation utilizes a finiteqdifferencescheme in order to estimate,from obtain an accurateestimate of the radiationand may also suffer from the straininformation, the displacement field in Rayleigh'sformula. Simu- aliasingproblems. Far-field sensors are often not suitabledue to environ- lationsare performedusing a givendisplacement field and the two formu- mentalconstraints. An alternativemethod is the useof shapeddistributed lationsare comparedin order to evaluatetheir effectivenessfor use in sensorson the structure,which act as low-passfilters in the wave-number active control schemes. domain.The useof thistype of sensorhelps to isolatethe radiating portion of thewave-number spectrum and is alsobeneficial in reducingthe number of sensorsrequffed to avoidaliasing. This work presentsnumerical results of usingshaped polyvinylidene fluoride (PVDF) film to predictthe far- 1:45 field radiatedsound. These results are comparedto the theoreticalresults and to the results obtained when discrete sensors mounted to the structure 4pSAa3. The acoustic characterization of a new reverberant water are used. tank. RichardWeyer, Dean Capone (Appl.Res. Lab., Penn State Univ., P.O. Box 30, StateCollege, PA), and RichardSzwerc (PennState Univ., StateCollege, PA 16802) 1:30 A reverberantwater tank has been constructedat the Pennsylvania 4pSAa2. Strategies for using strain sensing in active control of StateUniversity. The backgroundnoise, diffusivity of the soundfield, and the reverberation time in the tank have been measured as a function of acoustic radiation. Patrice Masson,Alain Berry, and Jean Nicolas (G.A.U.S., Mech. Eng. Dept., Univ. of Sherbrooke,Sherbrooke, PQ J1K frequencyin one-third octave bands, from 80 Hz to 63 kHz. The techq 2Rl, Canada) niquesused to characterizethe tank are presented.The characteristicsof the tank are comparedto otherknown water tanks.It is demonstratedthat Sensingapproaches used in activestructural acoustic control (ASAC) the tank is suitablefor the experimentaldetermination of the radiation are mainlyconcerned with monitoringacceleration, velocity or displace- efficiencyof a structureby comparingdata obtainedin this ta0•kwith ment of the structure,typically by meansof aceelerometersor PVDF, previouslypresented data for a fiat plate.[Work supported by ONR.] 3380 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3380 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 2:00 drivenon the sideopposite the blanketby an incidentacoustic wave. The modelis usedto computethe spatial distribution of thepressure on thetop 4pSAa4.Shape optimization of foam liners in double panel systems. surfaceof theblanket. The totalacoustic radiated power, normalized to the Y. J. Kangand J. S. Bolton (1077Ray W. HerrickLabs., School of Mech. magnitudeof the pressureincident on the plate, is computedfrom the Eng.,Purdue Univ., W. Lafayette,IN 47907-1077) surfacepressure. Examples of the effectivenessof homogeneousand non- Althoughelastic porous materials such as foamsare widely usedfor homogeneousblankets in reducingacoustic radiation are presented.The passivecontrol of aircraft and automobileinterior noisetreatments, nu- effectsof dampingin the blanketare alsoexamined. mericalmodels of thesematerials have only recently became available [Y. J. Kangand J. S. Bolton,J. Acoust.Soc. Am. (1995)].In the work de- scribedhere the proceduresof optimaldesign were combined with elastic 2:30 porousmaterial finite elementsto optimizethe shapeof the foam liners. Specially,the surfacecontour of the foam lining wasadjusted to minimize 4pSAa6. The use of structural coatings to attenuate transmitted the soundtransmission through a foam-lineddouble panel structure system flexural wave-inducedvibration. RichardF. Keltie (Ctr. for Soundand in a waveguide.This model is a simple representationof an aircraft fuse- Vib., Dept. of Mech. andAerospace Eng., Box 7910, North CarolinaState lage segment.The foam finite element was basedon a completeelastic Univ., Raleigh,NC 27695) porousmaterial theory that accountsfor the threewave typesknown to be This studyexamined the usedof a compliantcoating on a plate to significantin foams.The proceduresfor couplingthe foam finite element attenuate the transmitted structure-borne sound at the interface between the with adjacentacoustical and structural elements will alsobe presented.In coatingand the ambient acoustic medium. In orderto gainphysical insight theexample problems, a planewave is assumedto impingeon the incident into the problem,the layer was modeledas a fluid with dissipation.Al- surfaceof the doublepanel structure. The shapeand material parameters of thoughrealistic layers are likely to be visco-elasticmaterials, the fluid the foam linerswere usedas designvariables, and the performancemea- layerapproach has been used to providefor a tractableand useful analyti- surewas the frequency-averagedsound transmission loss in the frequency cal model.The performanceof the layermodel was evaluated by calcu- bandsof interest,e.g., the speechinterference range. lating the displacementfield at the layer/mediuminterface in responseto structuralexcitation. The 3-D wave-number-frequencyresponse amplitude 2:15 spectrumof the dynamiccompliance was examined. This providedfor the identificationof the dominantprocesses determining the layer response.A 4pSAa5. Tailoring material properties of acoustic blankets for simplephysical interpretation of theseresults was shownto involve the reducing radiated noise. CourtneyB. Burroughs (Grad. Prog. in dispersivecharacteristics of plate wavesand acousticwaveguides. It was Acoust.,Penn State Univ., StateCollege, PA 16804) shownthat the structuraleffects of the plate could be eliminatedfrom the The developmentand applicationof a mathematicalmodel that con- analysis,resulting in a model involvingonly the layer itself. The subse- sidersthe reductionin acousticradiation produced by varyingthe material quentperformance of the layeras a displacement(or velocityor accelera- propertiesof a viscoelasticblanket in the directionparallel to the surfaceof tion) attenuatoror amplifierwas then examined. [Work supported in part the blanketare presented.The blanketcovers an elasticplate which is by NavalUndersea Warfare Center, New London,CT.] FRIDAY AFTERNOON, 2 JUNE 1995 MEETING ROOMS 12, 13, 14, 3:15 TO 5:15 P.M. Session4pSAb Structural Acoustics and Vibration: Plates and Shells I JerryH. Ginsberg,Chair Schoolof MechanicalEngineering, Georgia Institute of Technology,Atlanta, Georgia 30332-0405 ContributedPapers 3:15 3:30 4pSAbl. Vibration and soundradiation of Mindlin platesincluding 4pSAb2.A modal/spectralanalysis of massdistribution effects in a in-planemotion, stiflened by thin walled beams. C. Locqueteauand fluid-loadedplate. JohnBabish and Jerry H. Ginsberg(School of Mech. A. Berry (GAUS, Dept.of Mech.Eng., Univ. of Sherbrooke,Sherbrooke, Eng.,Georgia Inst. of Technol.,Atlanta, GA 30332-0405) QuebecJIK 2RI, Canada) Feltand Johnson [J. Acoust. Soc. Am. 90, 2309(A) (1991)] showed that Stiflenedpanels such as thoseencountered in marinestructures may thesignal scattered by a plateis greatlyaffected by the spatialdistribution exhibitin-plane motion in the paneldue to the couplingwith the defor- mationof thestiffeners. Most of thepublished papers on Mindlin stiflened propertiesof an attachedmass. Ginsberg et el. [ASMEProc., paper 93- WA/NCA-20(1993)] used the surface variational principle (SVP), which platesdo not take into account the in-plane motion of thepanel. This paper presentsa vibroacoustic model of finite,stiflened panel including flexion, describesthe surfacepressure and displacementas a set of interacting shear,and in-plane motion of thepanel, and flexion, torsion, and warping waves, to examinea fluid-loadedplate with attachedpoint massin an of the thin-walledbeam stiflenets. The vibrationproblem is solvedthrough infinitebaffle. In their analysisthe massdistribution was representedas a a Rayleigh-Ritzapproach, both for the fluid-coupledand the uncoupled Fourier series in an effort to determine how coarsethe model could be, and cases.The numericalresults are comparedto recently publisheddata. Tl•e still accuratelyrepresent the directpoint ma• •olution.Their conclusion effectsof sheardeformation and in-planedeformation of the panelare wasthat a serieslength of eightterms is adequateto describethe system systematicallyinvestigated in termsof the panelresponse and soundra- behaviorin thefrequency range kL•<3, but a seriesof fewerthan six terms diation,and the resultsare comparedto a simplermodel retaining only is substantiallyinaccurate. The currentwork uses the in-vacuomodes of pureflexural deformation of the panel and stiflenets. [Work supported by thespectrally smoothed mass-plate system as Ritz functions for displace- DefenseResearch Establishment Atlantic, Contract OSC92-01908.] ment. The solutionin termsof these modesis comparedto the results 3381 d. Acoust.Sec. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3381 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp obtainedfrom the Fourierseries representation, in orderto identify why a attaintsis obtainedby usingthe neuralnetwork; third, the sensitivitiesof critical numberof terms is requiredfor the spectraldescription of mass theplate eigenvalue to designparameters (i.e., c)fb9Ri) around the point of distribution. originalgeometric design are obtained by usingthe trained neural network. Finally,the sensitivitiesof designparameters to eigenvalue(i.e., c•R/c•fi) are also obtainedby using the trainedneural network.The influenceof frequencyon geometricparameters, as well as the influenceof geometric 4pSAb3. Attenuation of waves in plates and bars using a graded parameterson frequency,is alsodiscussed. impedanceinterface. ChandrasekarVemula, Andrew N. Norris (Dept. of Mech. Eng., RutgersUniv., Piscataway, N]' 08855), GeorgeCory, andGerry V. Storch (ExxonRes. and Eng., Annandale, NJ 08801) 4:30 A new methodis proposedfor attenuationof reflectedenergy at the edgesof platesand bars, using a gradedimpedance interface. A standard 4pSAb6. Experiments on turbulent boundary layer/flexible approachis to embedthe plate edges in sand.However, it hasbeen verified structure/sound interactions in accelerated motion. L. Maestrello thata gradedimpedance interface at the edgesis far moreeffective in (NASALangley Res. Ctr., Mail Stop463, Hampton, VA 23681-0001) dampingthe radiatingstructural energy. It is well knownthat impedance mismatehcauses complete reflection of energyat the freeedge of a plate. Measurementsare made of the responseand acousticradiation of a Hence,it seemsreasonable to expecta reductionin reflectedenergy when panelstructure mounted in a windtunnel and forced by a subsonicturbu- impedanceis variedgradually. Experimental results for l-in. platesindi- lent boundarylayer and pure-tonesound. Measurements are madeat ac- catethat at most30% of theenergy is dampedfor frequenciesabove 2 kHz celeratedspeed because the resultantresponse exhibits a varietyof behav- whensand is used,whereas as much as 60%-80% of the energyis damped iorsdifferent from data at constantspeed. The structureexhibits broadband between2 and l0 kHz usinga gradedimpedance. Experiments on barsalso responsewith superimposedpure tone and its harmonicsover the band,a give similar results.A theoreticalformulation for a bar with gradedim- nonlinear,nonstationary, and non-Gaussianprocess. The mechanismby pedanceinterface at the edgesis presented,using both the Kirehhoffand which harmonicsare generatedbecomes clear as the amplitudesof the Mindlin theories.The Mindlin theorypredicts the level of energydamping fundamentaland low-frequencyband reducewith increasinglevel of the thatis observedin experiments,while the Kirchhofftheory predicts much harmonics--amanifestation of energytransfer. Active controlof the panel lesserenergy damping. The sheareffects are modeledmore accurately in responseusing a time-invariantsystem recovers losses in relativestability the Mindlin theoryand they seemto be importantin thisproblem. as it regainspartial reduction of the harmonics. 4:00 4pSAb4.A perturbationsolution for foi'cedresponse of systems 4:45 displaying eigenvalue veering and mode localization. Hoang Pham 4pSAb7. Observations of vibration-induced fatigue in steel using andJerry H. Ginsberg(School of Mech.Eng., Georgia Inst. of Technol., modal analysis. Scrag H. Arzoumanian,Douglas P. Kcehn, and David GA 30332) C. Swanson (Appl. Res. Lab., PennState Univ., P.O. Box 30, State Variousaspects associated with eigenvalueveering, such as extreme College,PA 16804) parametersensitivity and localizationof response,are of paramountim- The acceleration to force transfer functions across a shaker-excited thin portancefor predictingthe dynamicresponse of lightly coupledsystems bandunder tension with a deepnotch cut through its center is examinedup having nearly periodic components.This paper presentsa perturbation to thepoint of fatigue-indueedfailure. An analyticalmodel is developedto solutionthat simplifiesanalysis of forcedresponse of continuoussystems trackthe changesin modalproperties evident in the experimentalresults as whosefree vibrationeigensolutions display eigenvalue veering and mode a functionof band parameters.The progressionof the structuretoward localization.In this investigation,the classictwo-span beam with a strong failureis documentedby plotsof rotationalstiffness and crack lengthas a torsionalrestraint at the intermediatepin supportprovides a prototypefor functionof fatiguetime. developingthe perturbationsolution. Offset of the pin from the center positiondestroys periodicity of the two-spansystem, whereas the strength of the torsionalspring relates the extentof interspandecoupling. A study by Chen and Ginsberg[J. Vib. Acoust.114, 141 (1992)] establisheda 5:00 relationshipbetween the eigenfunctionsand the eigenvaluesfor different values of the pin offset. The previousfindings are mergedwith a Ritz 4pSAb8.Vibration analysisof triangular platesusing the ray-tracing expansionto formulatethe forcedresponse. The adequacyof the solution technique. R. Gunda,S. M. Vijayakar,and R. Singh (Acoust.and is determinedby comparisonsto resultsof baseline"Starm-Liouville- Dynam.Lab., Dept. of Mech. Eng., Ohio StateUniv., 206 W. 18thAve., type" analyses.Flexibility of the perturbationsolution is assessedin vari- Columbus,OH 43210-1107) ous case studiesof lightly coupledtwo-span systems. A newray-tracing technique is proposedfor the dynamicanalysis of thin platesin flexure.This approachis basedon the fundamentalsolution 4:15 to theplate biharmonic equation and suitably placed image sources which 4pSAb5. Sensitivity analysis of structural eigenfrequencyto plate simulatewaves reflected from theplate edges. In thispaper, this method is designparameters by using neural network. Z. Q. Yu, L. H. Yam, appliedspecifically to a classof triangularplates with certain aspect ratios. andT. P. Leung (Dept. of Mech. & Marine Eng., Hong Kong Polytech. •iince exact e•gensolutionsfor some plates with simply supportedbound- Univ.,Hung Hem, Kowloon,Hong Kong) ary conditionsare known, thesecases are analyzedfirst. The methodof imagesis alsobeing extended or arbitrarypolygonal plates where all the The dynamic characteristicsof plate structurecan be improvedby imagesources may not be seenby all pointsinside the plate unlikethe m'rangingthe naturalfrequencies of the systemin specifiedranges. The previouscases. Consequently, the imagesources have to be selectively sensitivitiesof structuraldynamic response to designparameters can pro- chosendepending on the excitationand observationpoints. Preliminary vide the essentialgradient information for derivingefficient optimization results,when comparedwith exact solutionsand •nite-elementcalcula- procedures.They are usedto form an approximateproblem for solvingthe tions, indicatethat this methodis capableof accuratelypredicting har- originalstructural optimization problem, while the sensitivityof geometric monicresponse. Another advantage of this techniqueis that the solution parametersto frequencycan provide the essentialgradient information for can be obtainedwithin a spectralbandwidth. Convergence studies show derivingefficient design procedures. In this paper,first the trainingset of that the error normsrapidly decrease with an increasein frequencyand neural network is generatedby the finite-elementmethod; second,the damping.Hence, this methodis computationallyefficient in the high- originaldesign of a cantileverrectangular plate with multifrequencycon- frequencyregime. [Work supported by theArmy Research Office.] 3382 J. Acoust.Soc. Am., Vol. 97, No.5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3382 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp FRIDAY AFTERNOON, 2 JUNE 1995 MEETING ROOM 16, 2:30 TO 4:45 P.M. Session4pSC SpeechCommunication: Prosody Sally G. Revoile, Chair Centerfor Auditoryand SpeechSciences, Gallaudet University, Washington, DC 20002 ContributedPapers 2:30 3:00 4pSCI. Some phrase-level influences on the glottal waveform. 4pSC3. Global durational patterns in spontaneousspeech. Douglas KennethN. Stevens (Res. Lab. of Elec. and Dept. of Elec. Eng. and O'Shaughnessy(INRS-Telecommun., 16 Placedu Commerce,Verdun, Camput.Sci., MIT, Cambridge,MA 02139) PQ H3E lH6, Canada) ¾ The prosodyof an utteranceis often describedin termsof the locations Most analysisof speechexamines carefully read texts. Natural spon- of attributessuch as pitch accents,boundary tones, and vowel reduction. taneousspeech differs in severalways, having interruptionsand large These prosodic descriptionsare usually representedin the sound by changesin speakingrate. The acousticphenomena studied here concern changesin fundamentalfrequency• duration, and other temporal and spec- the global speakingrate of spontaneousspeech, how it varies for both tral attributesof the segments.This paperpresents data showingthat the fluentand disfluentspeech. Such a model shouldfind applicationin auto- amplitudeand spectrumof the glottal pulses,as well as their frequency, maticspeech synthesis and recognition. There is a tendencyfor speakersto undergomodification depending on locationsof pitch accentsand bound- adopt a specificarticulation rate in fluent speech,especially for brief ary tonesand dependingon vowel reduction.The followingresults were monosyllabicfunction words; stressed content words show greatervari- obtained:(1) Reducedvowels tend to havesignificantly lower amplitude (7 ability,especially in prepausalsituations. The greatestvariability, however, to 13dB) thannonreduced vowels, together with an increasedfirst-formant occursin disfluentspeech, which have extremes in slowand fast speech. A bandwidthand an increasedtilt in the sourcespectrum; (2) a nonreduced largeamount of thevariability among word durations can be accounted for vowelhas a somewhatreduced amplitude (by about6 dB) whenit follows by: the numberof phonemesper word, whetherit is a functionword or a a nuclearpitch accent; and (3) a nonreducedvowel in utterance-finalpo- contentword, and whether iiae word forms part of a commonsequence of sitionin a declarativesentence shows a decreasedamplitude of the first- words.Words at the startof a syntacticunit tendedto be shorterthan those at the end of the unit. The first time a content word was introduced into a formantpeak, an increasedopen quotient, and an increasedspectrum tilt. discourse,it was stressed;repeated occurrences of such a word in the Productionmechanisms that could accountfor these changesinclude ensuingdiscourse had shortened durations. [Work supported by NSERC- modificationsin subglottalpressure, adjustments of the glottalconfigura- Canada.] tion,and influences of constrictionsin the supraglottal airway. [Work sup- portedin partby a grantfrom NIDCD.] 3:15 2:45 4pSC4. Acoustic and kinematic evidence for difference in language timing structure. MargaretH. Dunn (HaskinsLabs., 270 CrownSt., 4pSC2. Effects of stress, vowel duration, and vowel height on the New Haven, CT 06511) timing of pitch peaks in Czech. ChristineBartels (Linguist.Dept., SouthCollege, Univ. of Massachusetts,Amherst, MA 01003) Proposeddifferences in the timingorganization of Italianand Finnish are examinedfrom the perspectivesof simultaneousacoustic duration and Czech is describedas having word stressfixed on the first syllable, bilabialmovement (selspot tracked) collected from four native speakers of independentof vowelquantity. The pitchpeak of a wordgenerally falls on eachlanguage. All utteranceswere disyllabic, shaped CVC(C)V for Italian thatfirst, stressed syllable. However, in someenvironments, the pitchpeak andCV(V)C(C)V(V) for Finnish.Italian, generally believed to be syllable- shiftsto a later syllable,leading to the perceptionthat this later syllableis timed, showsregular acoustic intervals between vowels implemented by moreprominent. This studyinvestigated the phoneticfactors conditioning shorteningof the initial vowel in closedsyllables. Movement data shows suchdivergent placement of stressand pitchpeak in Czech.Native speak- that shorteningis achievedby early initiationof clustersand geminate ers producedcontextually embedded trisyllabic nonsense words wi:h high- consonants,truncating the initial vowel. Finnish, generallydescribed as pitch accents.Vowel heightand quantityin the first and secondsyllable moro-timed,shows increments of acousticduration of disyllabicutterances were independentlyvaried to assesstheir effect on syllablepitch and the with the addition of moros, either to vowels or to medial consonants.An timing of the pitch peak.Whether a syllablewas stressedconstituted the apparentconstraint on syllableduration leads to acousticshortening of third independentvariable in the analysis.To determinewhether stress bothinitial vowels and intervocalic consonants in thelonges[,utterances. remainedon the first syllable,the timingof stress-relatedproperties, i.e., Movementdata showthat increasesin quantityaffect both medialconso- amplitudeand gyllablelengthening. wa• examined.Regultg •howed that a nant and precedingvowel portion• of utteranceg.It ig propogedthat highvowel in eithersyllable tended to raisethe pitch,but the secondvowel syllable-timingworks directly from vowel to vowel, while mora-timing couldonly attractthe pitch peak if the first vowel was shortand low. A allowsincrease in durationof disyllabicutterances, adjusting both vowel longfirst vowel prevented accent shift to thesecond syllable. Stress-related and consonantdurations to fill out or limit the possibleintervals between propertiesremained largely confined to the first syllable,although the vowels.[Work supported by NIH GrantDC 00121 to HaskinsLaborato- amplitudemaximum occasionally shifted to the secondsyllable, if long. ries.] 3383 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3383 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 3:30-3:45 ' Break phrase-,and sentence-initial/n/'s havecumulatively more contact than medialand final ones. It is proposedthat greater initial contact contributes 3:45 to markingprosodic boundaries by enhancingthe consonant-vowelcon- trast.Also enhancing the CV contrastis themore open position for phrase- 4pSC5. Importance of tonal envelopecues in Chinese speech final/o/'s. As a result.final edgesof domainsare markedby a greater recognition. Qian-JieFu (Dept. of Biomed.Eng., Univ. of Southern articulatorydistance from final/n/to/o/, andinitial edges of domainsare Californiaand HouseEar Inst., 2100 WestThird St., Los Angeles,CA markedby a greaterarticulatory distance from final/o/to initial/n/. 90057), Fan-GangZeng, Robert V. Shannon,and Sigfrid D. Soli (House Ear Inst.,Los Angeles, CA 90057) 4:15 Temporalwaveform envelope cuesprovide significant information for 4pSC7.Intelligibility of Arab's production of English intonation. Englishspeech recognition, and, when combined with lip reading,could FaresMitleb (Dept. of English.Yarmouk Univ.. Irbid. Jordan) producenear-perfect consonant identification performance [Van Tasell et al., J. Acoust.Soc. Am. 82, 1152-1161 (1987)]. Tonal patternsare Thispaper was intended to testthe intelligibility of Englishintonation importantfor Chinesespeech recognition and can be effectivelyconveyed spokenby Arabslearning English as a foreignlanguage. Two nativeBritish by temporalenvelope cues [D. H. Whalenand Y. Xu, Phonetics49, 25-47 speakersheard English sentences produced by twonative British speakers (1992)].This study investigates whether tones can help Chinese-speaking and six Arabs to decidewhether a sentenceis saidwith a fallingor rising listenersuse envelope cues more effectively than English listeners. The tune.Findings indicated that most Arabs confused the two English tunes to speechenvelope was extracted from broad frequency bands and used to a significantlevel. They showedinsensitivity to the two intonationpat- modulatea noise of the same bandwidth.Mandarin vowels, 'consonants, terns.a situationthat mighthave resulted from the prioritygiven to the tones,and sentences were identified by tennative Chinese-speaking lis- teachingof segmentalunits of thetarget language. Therefore. the question tenerswith l, 2, 3, and4 noisebands (or channels).The resultsshowed of priorityto at leastthe incorporationof intonationalinformation and that recognitionof vowels,consonants and sentencesincreases dramati- othersuprasegmentals in the teachingprocess right from the outsetis cally with the numberof channels,a patternsimilar to thatobserved in reconsidered.[Research supported by YarmoukUniversity.] Englishspeech recognition. However, tones were consistently recognized at about80% correctlevel independentof the numberof channels.This 4:30 highlevel of tonerecognition produced a significant difference in open-set sentencerecognition between Chinese (11%) andEnglish (1%, p < 0.0 ! ) 4pSC8.Acoustic phonetic characteristics of internalopen juncture for the onechannel condition where no spectralinformation is available. by MexicanSpanish readers. HelenE. Karn (Dept. of Linguist, Georgetown Univ.. Washington,DC 20057-1068) and Grace H. 4:00 Yeni-Komshian(Univ. of Maryland,College Park, MD) 4pSC6. Demarcatingprosodic groups with articulation. Cecile Internalopen juncture refers to a setof two or morephrases which Fougeron(Phon. Lab, Dept. of Linguist.,UCLA, Los AngelesCA containthe same sequence of phoneroes,but differ in theirprosody, mean- 90095-i543 and Inst. de Phonet., Paris Sorbonne Nouvelle, Paris, France), ing,and orthography. In thisstudy, ten adultnative speakers of Mexican PatriciaA. Keating (UCLA, LosAngeles, CA) Spanishread three sets of phrases.Each set of phrasescontained two wordsand three syllableswith the sequence(la)g(sa), (las)g(a), and It ishypothesized thatphrasal position affects articulation, andthat (las)$(sa),as in thephrases la sabes"you know it." lasaves "the birds," whatlooks like overalldeclination of articulatorydisplacement could arise andlas sabes"you knowthem." The phraseswere read both in isolation fromlocal enhancements or reductions at particularphrasal positions. To andembedded m sentences(initial. medial. and final positions).Acoustic testthis hypothesis,lifiguopalatal contact was measured for boththe con- phoneticmeasurements were made of: (1) the durationof pauses(when sonant/n/andthe vowel/o/in reiterantspeech. Utterances were based on present)between the first orthographic word and the second. (2) thedura- arithmeticstatements like "(1+ 1)x(1 + 1)" [reiterant"(no no no) no (no tionof (s) and(ss), and (3) theaverage duration, fundamental frequency, nono)"], where stress and phrasing were varied by choice of numeralsand andamplitude of thefirst syllable versus the second. Preliminary results locationof parentheses.For theone speaker analyzed, there was no overall suggestthat internal open juncture in MexicanSpanish is moresalient in downtrendin contactof/n/through any sentence type when all syllables-- phrasesread in isolation than embeddedin sentencecontexts and that stressed,word-initial, or phrase-initial--werecompared. Instead, word-, pauseduration is themost consistent indicator of internalopen juncture. 3384 J.Acoust. Soc. Am., Vol. 97, No. 5, Pt.2, May1995 129thMeeting: Acoustical Society ofAmerica 3384 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp FRIDAY AFTERNOON, 2 JUNE 1995 GRAND BALLROOM SOUTH, 1:00 TO 4:50 P.M. Session4pUW Underwater Acoustics:Bottom Scattering Peter M. Ogden, Chair Naval ResearchLaboratory, Code 7142, 4555 OverlookAvenue, S.W., Washington,DC 20375-5350 Chair's Introduction--l:00 ContributedPapers 1:05 Soc.Am. 96, 3329(A)(1994)]. It wasfound that prominent returns register with extendedscarps facing the sourceand receivingarray. These scarps 4pUW1. Bottom backscatteringstrengths at low grazing angles typicallyextend for lengthsgreater than 1 km and have widthsthat are less using adaptive beamforming. Peter M. Ogden and Fred T. Erskine than I kin. However, the hydrosweepbathymetry is not of sufficientreso- (NavalRes. Lab., Code 7142, 4555 OverlookAve., SW, Washington, DC lutionto determinethe fine-scalegeomorphology of the scarps,and leads 20375-5350) to slopeestimates (20 ø to 30ø) thatare a severeunderestimate. Fine-scale Bouombackscattering strengths have beenmeasured between 70 and bathymetryof 5-m resolutionrecently obtained for the sameridge shows 1000 Hz usingbroadband, omnidirectional SUS chargesas sourcesand a that the scarpsreturning prominent reverberation generally contain cliff horizontalline arrayas a receiverin theCritical Sea Test (CST) seriesof faceswith slopesbetween 60 ø to 90ø . However,the separationbetween at-seatests. When conventional beamforming is usedto formbeams in this thesecliff facesis typicallyless than the roughly 500-m cross-range reso- geometry,bottom fathometer returns often contaminate the backscattering lutionof the towed-arrayimaging system. An attemptis madeto resolve resultsfor grazingangles below about30 deg. The use of an adaptive individualcliff faceswith remotereturns measured at 1/2 CZ by exploiting beamformer(ABF) combinedwith examinationof' near-endfirebeams al- the much higher range resolutionof the towed-arrayimaging system lows scatteringstrengths to be reliably determineddown to considerably (whichapproaches roughly 10 m) andexamining differently oriented bi- lower grazingangles in many cases,over the entirerange of frequencies static measurements of the same sites. measured.The ABF techniqueand its parametersand limitationswill be discussedbriefly. Examples of low-grazing-anglebackscattering-strengths resultswill be shownfor a varietyof sitesvisited during various CST tests. 1:50 [Worksupported by ONR.] 4pUW4. Backscatter from midfrequency (325-1375 Hz) LFM 1:20 signalsat the Mid-Atlanticridge. J.R. Preston(Appl. Res. Lab., Penn StateUniv., P.O. Box 30, StateCollege, PA 16804) 4pUW2. Shallow water bottom scattering strength at low frequencies. Peter G. Cable (BBN Systemsand Technol.,Union In July 1993 SACLANTCEN participatedin an experimentfor the Station, New London, CT 06320-6147), Mike Steele, and James AcousticReverberation Special Research Program (ARSRP). The primary O'Connor (BBN Systemsand Technol., Arlington, VA 22209) objectivewas to take high-resolutionmeasurements to shed light on the detailedphysical processes dominating the low-frequencyscattering from Determinationsof acousticscattering strength for sand bottomshave rough topographicfeatures and from deep sedimentpond areas.A very beenmade at severalshallow water sites under downward refracting sound detailed set of monostaticand bistatic scatteringexperiments were con- propagationconditions in the frequencyband 50 Hz to 1 kHz. The mea- ducted(using lower frequencies from 200-375 Hz) just westof the Mid- surementshave been made using explosive sources detonated at mid-water AtlanticRidge near 26 øN and 47 øW. New resultsare presentedwhich depthand receivedon two collocated,bottom-mounted hydrophone line show higher frequencymonostatic scattering from selectedbathymetric arrays,with one array in verticaland the other in horizontalorientation. featuresusing LFM signals.The receiverswere horizontalarrays of 128 The majorfocus of this work hasbeen the variationof scatteringstrength elementsspaced at 0.5, 1, and2 m. Source/receiverdepths were •130 and with frequencyand with bottomgrazing angle. For the scatteringstrength 450 m, respectively.Received reverberation levels are presentedas func- measurements,the presenceof multipathsin shallow water preventsa tionsof the estimatedscatterer position on area bathymetrymaps. Infer- directpath scatteringgeometry from beingused at low frequenciesand, encesfor monostaticbottom scattering mechanisms are given usingtwo- consequently,scattering strength must be extractedfrom the full reverbera- way FEPE parabolicequation propagation models from Collins to interpret tion field.Two techniquesfor obtainingscattering strength integrated over the data. Some comparisonsof measuredand modeledreverberation are grazing angle and for using the vertical array to examine the angular also presented. dependenceof the scatteringstrength will be described.The resultswill be comparedwith other determinations of scattering strength for shallow wa- ter sandbottoms and will be discussedin terms of the role of scattering 2:05 from structure within the bottom sediment. 1:35 4pUW5. Pulse length dependencein the CST bottom reverberation measurements.Sean M. Reilly (TracorAppl. Sci., Inc., Anal. and 4pUW3. Preliminary comparisonsbetween bistatic reverberation Simul. Dept., 35 ThomasGriffin Rd., New London,CT 06320), from an oceanridge and wavelength-scalegeomorphology. Nicholas RaymondJ. Christian,John B. Chester,and Mark J. Vaccaro (Naval C. Makris. Lilimar Avelino, and Richard Menis (Naval Res. Lab.. UnderseaWarfare Ctr., New London,CT) Washington,DC 20375) The Critical Sea Test (CST) is an empiricalNavy programwhich Bistatic reverberationmeasured from a highly lineated ridge in the collectslow-frequency (100-1000 Hz) environmentalacoustics measure- mid-Atlanticduring the ARSRP Main AcousticsExperiment of 1993was mentsin order to providea diverse,high-quality database for sonarper- comparedwith bottomslope orientation determined from 200-m resolution formanceprediction. During the courseof its experimentsin directpath Hydrosweepbathymetry in a previousabstract [Makris et al., J. Acoust. bottomreverberation, CST has observedfrequency, grazing angle, and 3385 d. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3385 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp waveformbehaviors which differ significantlyfrom thoseassumed in com- 2:50-3:05 Break monly availablebottomscattering strength models. For empiricalpro- grams,deviations from standardmodels are significantbecause they limit the ability to extrapolatesurvey measurements into sonarperformance 3:05 scenarios.The mostcontroversial aspect of the coherentsource experi- 4pUWg. Further results from modeling deep-oceanreverberation mentshas been the observationof a pulselength dependence in the seat- from the Mid-Atlantic ridge, StanleyA. Chin-Bing (NavalRes. Lab., teringstrength measurements beyond the linearterm normally associated StennisSpace Center, MS 39529-5004)and JosephE. Murphy (Univ.of with ensonifiedarea. This paper discusses CST's bottomscattering strength New Orleans,New Orleans,LA 70148) measurementtechnique and summarizes the pulse length "anomaly" re- sultsfor a varietyof geographicareas. Because these results run counter to Resultscornparing computer model simulations and reverberation data standardmodeling assumptitns, this paper will alsodiscuss the data qual- [Chin-Bingand Murphy, J. Acoust.Soc. Am. 96, 3328(A}(1994)] have ity procedurtsused to reachthese conclusions. [Work supportedby beenreported previously. The reverberationdata were taken from the Mid- SPAWAR.] Atlanticridge regionduring the 1993Acoustics Experiment as part of the ONR AcousticReverberation Special Research Prograte (ARSRP). A rep- resentationof the rough,range-dependent ocean sediment and sub-bottom bathymetryof theregion was obtained from getmorphological models (the Webb-lordan sediment distribution model and the Golf-Jordan fractal seafloor/basementmodel). A modifiedversion of the Collins •P•2WA¾ 2:20 modelwas usedfor the long-rangereverberation predictions. Our model simulationscompared favorably with 210- to 290-Hzbandwidth reverbera- 4pUW6. Preliminary study of the semi-empirical getacoustic tion datagathered from "siteA, seg076." In this continuingstudy of site (SEGA) model for bottom reverberation. Senn M. Reilly (Tracor A, seg 076, the FFRAMEand SAFEmodels are being used to study the Appi. Sci., Inc., Anal. and Simul. Dept., 35 ThomasGriffin Rd., New influenceof heavily sedimentedregions on reverberation.New modeling London,CT 06320) resultswill be presentedand comparedwith the measuredreverberation. [Work supportedby Office of Naval Research,Acoustic Reverberation Standardbottom reverberation models such as Lainbert'srule and per- SRP, and a High PerformanceComputing DoD SharedResource Center turbationtheory assume that scatteringfrom the roughwater/bottom inter- grant.] face is the dominantmechanism at all sonarfrequencies. However, direct path bottomscatteringstrength measurements by the Critical Sea Test (CST)program in the 100-to 1000-Hzfrequency range suggest that vol- 3:20 ume scatteringfrom withinthe sedimentsmay be thedominant reverbera- tionmechanism inmany applications. TheCST program has been actively 4pUW9. Effects of azimuthal coupling on bistatic reverberation. investigatinga number of newbottom reverberation models which include KevinB. Smith (Dept.of Phys.,Code PH/Sk, Naval Postgrad. School, Monterey,CA93943), WilliaraS.Hodgkiss (Scrippslnst. of Oceanogr., scatteringfrom withinthe sediments[Mourad et al., APL/U•VTech. Rep. ]•aJolla, CA), and FrederickD. Tappert (Univ. of Miami, Miami, FL) No. 9107(1991); Holland et el., J.Acoust. Soc. Am. 96, 3247(A)(1994)]. Using a combinationof elementsfrom theseprior techniques,the Semi- The Universityof Miami PE (UMPE) model[K. B. Smithand F. D. EmpiricalGeoacoasti6 (SEGA} model for bottomreverberation is usedto Tappert,MPL Tech.Memo. 432 (1993)] hasbeen upgraded to include extrapolategetacoustic survey measurements into general-purposerever- azimuthalcoupling, making it a fully three-dimensionalforward propaga- berationpredictions. This presentation summarizes the results of a prelimi- tion model.B•/incorporating Tappert's PE reverberation(PEREV) model nary3-month study which explored the viabilityof this new modelusing iF. D. Tappert,J. Acoust. Soc. Am. Suppl.1 88, S84(1990)], the effects of directpath bottom reverberation measurements from CST-5. [Work sup- azimuthalcoupling on bottom reverberation can be examined. Duririg the portedby SPAWAR.] July 1993ONR-ARSRP main acoustics cruise, extensive bistatie data were recorded.using bathymetrie data from the ARSRP Natural Laboratory, predictionsof bistaticreverberation are madewith and withoutazimuthal coupling.Differences between these two calculationS'providequantitative evidenceof azimuthalcoupling effects. Comparisons with measureddata will alsobe presented.[Work supported by ONR, Code321OA.] 2:35 4pUW7. Bottom loss measurements and analysis in the eastern Mediterranean sea. Dmitry Chizhik (Naval UnderseaWarfare Ctr., 3:35 New London,CT 06320) • 4pUWI0. The influenceof sedimentscattering and variability on acoustic intensity including data comparisons. Keith J. Howell, Wideband bottom loss measurements were conducted at two sites in Melvin J. Jacobson,William L. Siegmann (RensselaerPolytech. last., theeastern Mediterranean. The datawere processed incoherently to deter- Troy,NY 12180-3590),•md WilliamM. Carey (Adv.Res. Projects minebottom-loss inbne octave bands at center frequencies ranging from Agency,Arlington, VA 22203-1714) 200 to 4000 Hz and spanninggrazing angle range of 10ø-90ø. Geological Previouswork [Howell et el., J.Acoust. Soc. Am. 95, 2928 (1994)] has literatureindicated that the bottomat Herodotusabyssal plain locationwas shownthat statistics of multimodalintensity could be matchedusing a a "fast" turbiditcbottom, while the Nile conesite was characterizedby a three-layerisospeed model that includedeffects of scattering.To more "slow"silty-clay bottom. •['he bottom loss model was for•nulated foreach aecuratelyestimate scattering effects on intensityover a brOadfrequency site and was found to be in good agreementwith the data.A geometricray range,additional bottom information must be included.In this paper,an modelis often used for bottom loss prediction which includes the refracted analytictreatment of a shallowchannel consisting of n isospeedlayers is (diving)wave arrival at theproper grazing •angle. This•pproach works developedfor a wide-anglePE propagationmodel. A scatteringlayer is well at high frequenciesand high grazingangles, but gives erroneously introduced at a horizontal water-bottom interface to model effects of at- low bottom loss values at low frequenciesand low grazing angles.A tenuationdue to interfaceand sedimentscattering. The local meanof hybridray/plane wave modelwas developedto accountfor the additional intensityis •leterminedand its sensitivityto parameterssuch as the number loss due to penetrationof the wave into the sedimentin excessof that of layers;frequency, scattering layer thickness, and correlation length of predictedby thegeometric ray theory.This correction is mostimportant for inhomogeneitiesis investigated. The standard deviation of intensityis also "slow" bottomsat low grazingangles and low frequencies,as demon- examined.Comparisons are made betweenintensity statistics for the stratedby comparisonto data. multilayermodels and depth-dependent profile models consistent?ith data 3386 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3386 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp froma New JerseyShelf experiment. Additional emphasis is directedto- 4:20 wardthe number of isospeedlayers needed to matchexperimental intensity overa rangeof frequencies.[Work supported by ONR.] 4pUWI3, Effects of bottom type variability on modeled backscattered levels of a high-frequency sonar. Kristen D. Savage and Roger W. Meredith (Naval Res. Lab., Code 7174, StennisSpace 3:50 Center, MS 39529) 4pUWll. New multiple scatter model of the oceansediment, Dennis Resultsinvestigating the effectsof variable bottomcomposition on J. Yeltonand NicholasP. Chotiros (Appl. Res. Labs., Univ. of Texas, modeledhigh-frequency backscattered levels are presentedfor a typical Austin, TX 78713-8029) shallowwater, range-dependentenvironment. The modeledenvironment consistedof a singlesound-speed profile, a flat sea bottomwith range- Reflection,transmission, and scatteringproperties of an inhomoge- neous Blot medium were studied via numerical simulation. The inhomo- dependentbottom composition, and a benignsea surface. Coarse and fine grainsandy areas were partitioned in rangeto createrange dependence. geneousmedium was boundedby a semi-infinitewater medium on the Bottombackscattering and reflection loss for eachpartition were obtained sourceside, and a semi-infiniteBlot mediumof equivalentaverage prop- from the recentUniversity of Texashigh-frequency ocean bottom back- ertieson the otherside. The inhomogeneousmedium was simulated as a scattermodel IN. P. Chotirosand E A. Boyle, J. Acoust.Soc. Am. 96, randomlylayered Blot material.Each layer represented a granular material 3264(A) (1994)]. Differencesof 5 dB werediscernible between the fine- of particulargrain size. By settingthe thicknessof eachlayer equal to a coarse-finesand bottom and a range-independentfine sandbottom for randomgrain size, a randomlystratified granular medium was simulated. ranges<500 m. The trendand structure of the backscatteredlevels were Lateralvariations in grainsize were simulatedby performinga coherent nearlyidentical for bothbottom types. Differences of 42 dB for ranges ensembleaverage of resultsfrom severalrealizations of the randomly <500 m were visible in the modeled backscattered level of the fine- stratifiedmedium. The free parameterswere the grainsize meanand stan- coarse-fine sand bottom and the coarse-fine-coarse sand bottom. The darddeviation. Other parameters were chosen to representwater-saturated trend and structure of the backscattered levels were also different. In all sand.Reflected and transmittedsignals were computedfor a 1-MHz nor- cases,surface reverberation had a strongimpact on the backscatteredlev- mally incidentplane wave. Coherent and random components of the re- els, trends,and structures.[Work supportedby MCM TacticalEnviron- flectedsignal were calculated. The randomcomponent was related to the mentalData Systems (MTEDS) under Program Element 62435N.] scatteringstrength of themedium. It wasfound to increasewith boththe meanand the standarddeviation of the grain-sizedistribution. The results areconsistent with previousexperimental results [Nolle, J. Acoust.Soc. 4:35 Am.35, 1394-1408(1963)]. [Work supported by ONR code1125OA.] 4pUW14.Acoustic scattering by marinesediments with irregularities 4:05 of differenttypes. AnatoliyN. Ivakin (N. N. AndreevAcoustics Inst., Shvernika4, Moscow 117036, Russia) 4pUW12. High-frequency acoustic penetration into seafloor Thereare two differenttypes of irregularitiesgiving the maincontri- sediments at subcritical grazing angles due to roughnessat the butionsto bottomscattering: volume inhomogeneities of the sediment and water-sedimentinterface. Eric I. Thorsos (Appl.Phys. Lab., Univ. of roughnessof its surfaceand interfaces. The problemof distinguishing Washington,1013 NE 40thSt., Seattle,WA 98195) and/orseparating these contributions is considered using differences in Acousticpenetration into sediments at lowgrazing angles is of interest frequency-angulardependencies of the scattering coefficient and analysis for buriedmine detection. For sandy sediments the critical angle can be in of thespatial autocorrelation function of thescattered field. The volume the25ø-30 ø range, which suggests that penetration at lowergrazing angles inhomogeneitiesof the sediment in turncan be considered as oneof two mightbe quite limited. It will be shown,however, that when the sediment types:spatial fluctuations of density and fluctuations of sound velocity. For roughnessis modeled to beconsistent with the occurrence of sandwaves, water-saturatedsediments (without gas), density fluctuations are usually thensignificant penetration into the sediment can occur at subcriticalgraz- strongerand their contribution to thetotal volume scattering is muchmore ing anglesdue to scatteringat the roughinterface. An integralequation thanthat due to soundvelocity fluctuations. But evenlow concentrations method is used to obtain acoustic fields near the surface to illustrate the of gasbubbles can alter acoustic properties of sedimentsconsiderably, degreeof penetration.A 1-D surfacemodel is used,and the sedimentis reducingthe effective (average) sound velocity and enhancing fluctuations modeledas a fluid.For a givensurface profile, the acousticpenetration is of soundvelocity, with virtually no effect on thedensity. As a result,some foundto increaseas the frequencyincreases. When the frequencyis re- specificfeatures appear in soundscattering, and these can be usedfor ducedto bringthe roughness into the perturbation theory region, acoustic remote acoustic characterizationof sedimentsand determinationof the penetrationis much reduced. [Work supported byONR.] typeof bottomirregularities. [Work partially supported byONR.] 3387 J.Acoust. Soc. Am., Vol. 97, No. 5, Pt.2, May1995 129thMeeting: Acoustical Society of America 3387 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp FRIDAY AFTERNOON, 2 JUNE 1995 MEETING ROOM 17, 1:30 P.M. Meeting of Accredited Standards Committee S3 on Bioacoustics to be heldjointly with the U.S. TechnicalAdvisory Group (TAG) Meetingsfor ISO/TC 43 Acoustics,IEC/TC 29 Electroacoustics,and ISOfYC 108/SC4 Human Exposure to Mechanical Vibration and Shock T. A. Frank, Chair S3 Penn State UniversitySpeech & Hearing Clinic, 110 Moore Building, Universit),Park, Pennsylvania16802 R. F. Burkard, Vice Chair S3 BostonUniversity Dept. of CommunicationDisorders, 635 CommonwealthAvenue, Boston, Massachusetts 02215 P. D. Schomer,Chair U.S. TechnicalAdvisory Group (TAG) for ISO/TC 43, Acoustics U.S. CERL, P.O. Box 4005, Champaign,Illinois 61820 H. E. von Gierke,Vice ChairU.S. TechnicalAdvisory Group (TAG) for ISO/TC 43, Acousticsand ISO/TC 108/SC4, Human Exposureto MechanicalVibration and Shock 1325 MeadowLane, YellowSprings, Ohio 45387 V. Nedzelnitsky,U.S. TechnicalAdvisor (TA) for IEC/TC 29, Electroacoustics NationalInstitute of Standardsand Technology(NIST), Building 233, RoomA149, Gaithersburg,Maryland 20899 StandardsCommittee S3 on Bioacousfics.The current status of standardsunder preparation will be discussed.In additionto those topicsof interest,including heating conservation, noise, dosimeters, hearing aids, etc., consideration will be givento newstandards whichmight be neededover the nextfew years.Open discussion of committeereports is encouraged. The internationalactivities in ISO/TC 43 Acoustics,and IECFI'C29 Electroacoustics,and ISO/TC 1081SC4Human Exposure to MechanicalVibration and Shock, will alsobe discussed.The Chairsof theU.S. Technical Advisory Groups for ISOFFC43 (H. E. yon Gierke),and IEC/TC 29 (V. Nedzelnitsky),will reporton currentactivities of theseTechnical Committees and Subcommittees. Scopeof S3: Standards,specifications, methods of measurementand test, and terminology in the fieldsof mechanicalshock and physiologicalacoustics, including aspects of generalacoustics, shock, and vibralion which pertain to biologicalsafety, tolerance, and cor•or[. 3388 J.Acoust. Soc. Am., Vol. 97, No. 5, Pt.2, May1995 129thMeeting: Acoustical Society of America 3388 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp FRIDAY AFTERNOON, 2 JUNE 1995 MEETING ROOM 17, 3:00 P.M. Meeting of AccreditedStandards Committee S1 on Acoustics to be held jointly with the U.S. TechnicalAdvisory Group for ISO/TC 43 Acousticsand IEC/TC 29 Electroacoustics G. S. K. Wong,Chair S I, Institutefor NationalMeasurement Standards (INMS) National Research Council, Ottawa, Ontario KIA OR6, Canada R. W. Krug, Vice Chair S 1 Cirrus Research, Inc., 6423 West North Avenue, Suite 170, Wauwatosa, Wisconsin 53213 P. D. Schomer, Chair U.S. Technical for ISO/TC 43, Acoustics U.S. CERL, P.O. Box 4005, Champaign,Illinois 61820 H. E. yon Gierke,Vice ChairU.S. TechnicalAdvisory Group (TAG) for ISO/'I'C43, Acoustics 1325 MeadowLane, YellowSprings, Ohio 45387 V. Nedzelnitsky,U.S. TechnicalAdvisor (TA) for IEC/TC 29, Electroacoustics NationalInstitute of Standardsand Technology(NIST), Building233, RoomA149, Gaithersburg,Maryland 20899 Standards StandardsCommittee SI on Acoustics.Working group chairs will reporton theirpreparation of standardson methodsof measure- mentand testing, and terminology, in physicalacoustics, electroacoustics, sonics, ultrasonics, and underwater sound. Work in progress includesmeasurement of noisesources, noise dosimeters, integrating sound-level meters, and revision and extension of soundlevel meterspecifications. Open discussion of committeereports is encouraged. The international activities in ISO/'rc 43 Acoustics, and IEC/TC 29 Electroacoustics.will also be discussed.The chairs of the respectiveU.S. TechnicalAdvisory Groups for ISO/TC43 (H. E. yonGierke), and IEC/TC 29 (V. Nedzelnitsky),will reporton current activities of these Technical Committees. Scopeof SI: Standards,specifications, methodq of measurementand test and terminology in the fieldof physicalacoustics including architecturalacoustics, electroacoustics, sonics and ultrasonics,and underwatersound, but excludingthose aspects which pertain to biologicalsafety, tolerance and comfort. SATURDAY MORNING, 3 JUNE 1995 MEETING ROOM 3, 8:25 A.M. TO 12:00 NOON Session 5aMU Musical Acoustics:General Topics Uwe J. Hansen,Chair Departmentof Physics,Indiana State University,Terre Haute, Indiana 47809 Chair's Introductions8:25 Invited Papers 8:30 5aMU1. Interactionof lips and mouthpiecein a brassinstrument. GabrielWeinrcich and Fang-Chu Chen (RandallLab, of Phys.,Univ. of Michigan.Ann Arbor, MI 48109-1120) Thedifference between the frequency of a playednote on a brassinstrument and the frequency of theresonator (defined as the locationof themaximum of its inputimpedance at themouthpiece) has been experimentally investigated. To avoidthe complexity of thelips interacting simultaneously with many modes, a Helmhoitzresonator with an attached "mouthpiece" whose diameter is thatof a trumpetwas used. By havinga loudspeakerasone of thewalls of theresonator, and driving it witha signalderived from an attached 3389 d. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 12õthMeeting: Acoustical Society of Arner/ca 3389 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp microphone,it was possible to adjustboth the resonant frequency and the Q. Theinput impedance is measured (without the player's lipsleaving the mouthpiece)by comparingthe passive response of theresonator with andwithout a knownincrease in volume.In the considerablemajority of cases,the playing frequency is higherthan the resonator frequency, indicating that the lips "beatoutwards." Possibleerror sources will be discussed.[Work supported by NSE] 9:00 5aMU2. Acousticsof a bell with a tube on [Is head. TongChen (Inst. of Acoustics,Aced. Siniea,100080 Beijing, People's Republicof China) Templebells in Koreaare quite special as compared with bellsin othercountries. The bell hasa tubeon its headand a pit or cavity ("rumblingstructure") under it. The acousticalbehavior of thebell andits pit hasbeen modeled as a cylindricalcavity with an air gap. The air gapchanges the modefrequencies and damping factors of the cavity;the dampingfactor increases sharply with increasein lengthof the air gap,especially for somemodes. In real cases,the air gap betweenthe bell and the rumblingstructure is limitedto 0.3-0.4 m. The tubeon the bell is effectivefor radiationof soundonly whenits lengthis nearlyan integertimes the half-wavelength of a cavity mode.It is reasonableto adjustthe tubelength for the mostprominent partial in the bell sound,which determines the strike note.The acousticmode frequencies can be tunedby adjustingthe depthof the pit andthe lengthof the tubeto improvethe timbre of the bell sound. 9:30 5aMU3. Musical pitchnessevaluation through pitch extraction. AlexandraGalembo (47 FurstadtskaiaSt., #17, 191123St. Petersburg,Russia) •l•mbreand pitchare differentproperties of soundaccording to the ASA definition,but they are closelyconnected in the sounds frommusical instruments. An interestingproperty is the "pitehness"(or "pitchstrength") which refers to thedistinctivehess of pitch in thesound. This propertywas investigated for pianonotes, in particularin thebass and treble. In theseranges, the degree of pitchness is an importantfactor in determininginstrument quality. Pitch extraction methods were used to calculatea noisefactor in the treble, and an inharmonicityfactor in the bass.New methodsfor judgingthe soundquality in the treble,and for measuringand evaluating inharmonicityof bassstrings are proposed. [Work supported by "RedOctober" piano factory, St. Petersburg,Russia, and Swedish Institute,Stockholm, Sweden.] Contributed Papers 10:00 was observedthat the force pulseof a hammerstriking an infinite string was qualitatively similar to the impulseresponse of a second-orderfilter 5aMU4. An efficient time-domain model for the piano using with two real poles.Hence, good second-and higher-orderfilter designs conunutedelements. JuliusO. Smithand Scott A. VanDuyne (Ctr.for basedon physicaldata werepossible. However, multiple humps may ap- Comput.Res. in Musicand Acoust. (CCRMA), Deptof Music,Stanford pear in the hammerforce pulseon a terminatedstring due to returning Univ., Stanford,CA 94305) stringwaves. It was observedthat the magnitudespectra of the single A new time-domainmodel for the piano is proposedwhich is ex- hump spectrumand the multiplehump spectrumwere similarin band- tremely efficientfor synthesizingpiano soundsin hardwareor software. width,differing only in a slightringing in the lower spectrumdue to the The modelincludes multiple coupled strings, a nonlineardamped-spring lowpassedcombing effect of the returningstring waves. Therefore, an hammermodel, and a linear soundboardand enclosurecomponent which equalizationfilter was designed to summarizethis combing effect by fitting can havearbitrarily large order at very low cost.Simplifications based on a bank of parallel second-ordersections to the complexratio spoctrum. the commutativityof linear,time-invariant systems greatly reduce compu- Excellentlinear piano hammer simulations were produced. tationalcomplexity IComput. Music $. 74-91 (Winter1992); Proc. Inter- nationalComputer Music Conference, Tokyo, pp. 56-71 ]. The hahnnet- stringinteraction is highlynonlinear and thereforedoes not commutewith 10:30 othercomponents, in principle.However, by introducinga very mild ap- proximationhaving little or no impacton the sound,commutativity can be 5aMU6. A passive nonlinear digital filter design which facilitates achieved,leading to the enormouscomputational savings. This presenta- physics-based sound synthesis of highly nonlinear musical tion will review the derivationof the piano synthesismodel with special instruments. ScottA. VanDuyne and Iohn R. Pierce (Ctr.for Cornput. emphasison the nonlinearhammer component. In its presentform, a com- Res.in Music andAcoust., Dept. of Music, StanfordUniv., Stanford,CA plete,two-key piano can be synthesizedin real time on a singleMotorola 94305) DSP56001 signal processingchip with 8K words of static RAM and a clock rate of 25 MHz. Nonlinearifies,small or large, favorablyaffect the soundsof many musicalinstruments. In gongsand cymbals, nonlinearities cause the pas- sive trm•sfcrof energy from lower frequency modes to higher frequency 10:15 modesafter the instrumenthas beenstruck. While manyspectral modifi- 5aMU5. A linear filter approximation to the hammer/string cationscan be achievedby the inclusionof memorylessnonlinearities interaction for use in a commuted synthesispiano model. Scott A. (suchas square-law or tablelook-up) within the resonant loops of physics- VanDuyne and Julius O. Smith,III (Ctr.for Cornput.Res. in Musicand baseddigital sound synthesis algorithms, energy conservation cannot be Acoust.,Dept. of Music, StanfordUniv., Stanford,CA 94305) achievedwithout compensating amplitude scaling. In fact,the greaterthe nonlineareffect desired, the more difficult it is to maintainpassivity. Yet, In commutedsynthesis of string instruments,the soundboard/body for gongsand cymbals,a very largenonlinear effect is required.A com- resonatoris commutedto the excitationpoint and replacedby its own putationallyefficient nonlinear digital filter has been designed based on a impulseresponse [Smith and Van Duyne, elsewherein this session]. physicalsystem constructed from passive lossless elements only. This filter Hence,the highlynonlinear hammer/string interaction must be replacedby may be incorporatedinto any physicalmodeling algorithm (such as a cornmutablelinear filter. Using the wave digital hammercomputational Karplus-Strong,digital waveguide,or 2D digital waveguidemesh) where modelof the pianohammer [J. Acoust.Soc. Am. 96, 3300(A) (1994)], it travelingwaves are beingcomputed. System loss is decoupledfrom the 3390 d. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3390 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp nonlineareffect, and may be designedindependently. Further, system en- cam sectionswere produced,and pressurespectra, correlation dimensions ergyspreads locally in the spectrum,as is foundin real musicalinstru- D, and Lyapunovexponents were calculated.The multiphonicspectra ments;the rate and spectralregion of energyspreading is controllable. were biperiodicand phase-locked.For singletones D=I.0-1.1, and for Promisinggong sounds have been produced. multiphonicsD=2.2-2.5. The largestexponent for bothsingle tones and multiphonicswas smalland positive;for example,the informationloss 10:45 was 1 bit per44 periodsfor thewritten note E• and 1 bit per68 periodsfor E5. The slightlypositive Lyapunov exponent and the valuesD>I for 5aMU7. Horn reflectanceupdate. David Bernersand 1uliusO. Smith, singletones, and D>2 for multiphonics,may be interpretedas the infor- III (Ctr. for Cornput.Res. Music andAcoust., Stanford Univ., Stanford, mationloss due to slight fluctuationsof a performerwho maintainsa CA 94305-8180) steadytone. This result represents a significant difference between human performanceand physicalmodeling of musicaltone production. The flaredhorn is modeledaccording to Webster'sequation. A change of variablestransforms the equationinto the form of the one-dimensional Schr'odingerwave equation. The Schr6dingerform facilitates specification 11:30 of arbitraryaxisymmetric wavefronts for the acousticdisturbance within the horn.To providea physicallymotivated choice of wavefrontshape, 5aMU10. Sound spectra from air-driven American organ reeds. Poisson'sequation is solvedinside the hornsubject to the boundarycon- JamesP. Cottingham,Ben L. Colson,Scott T Wilson (Phys.Dept., Coe dition that the normalcomponent of the potentialgradient is 2ero at the College,Cedar Rapids, IA 52402),and KeelynW. Quigley (Coe boundaryof the hortl. Sincethe disturbancewithin the horn mustsatisfy College,Cedar Rapids, IA 52402) the waveequation, the velocity potential satisfies Poisson's equation when The "American" reed organ is distinguishedfrom the "European" viscouseffects and losses are ignored. Physical data from brass instrument harmonlureby the useof a partialvacuum to drawair pastthe freereeds bells are used to model musicalhorns using the Poissonsolution, and ratherthan the useof a pressurebellows to drivecompressed air through resultsare compared to thoseobtained by traditionalmodels which assume them.A sampleof reedsfrom threeinstruments has been studied in the sphericalwavefronts. Results are also compared to acousticmeasurements. laboratoryusing a speciallyconstructed windchest. Spectral analyses of nearfield soundproduced by air-drivenreed vibrations were obtained. 11:00 Measurementswere made of the variationwith pressureof the frequency and amplitudeof the fundamentalas well as the spectralcomponents. SaMUS. Equivalenceof finite differenceapproximation and digital Relationshipsbetween certain aspects of reeddesign and the spectrum of waveguidemodeling for lossless,nondispersive media in one to three the resultingsound can be comparedwith some"conventional wisdom" dimensions.Julius O. Smithand Scott A. Van Duyne (Ctr. for Cornput. found in the literatureon the instrument.Results are alsocompared with Res. in Music and Acoust.(CCRMA), Dept. of Music, StanfordUniv., spectraobtained when these reeds are played in the instrumentsand with Stanford,CA 94305) averagedsound spectra from the instruments. It is foundthat the frequency The finite differenceapproximation method is commonlyused to con- remainsessentially constant over a very wide pressurerange, and that the vert a differentialequation into a recursirecomputation for computer soundspectrum from a givenreed, although modified somewhat by its simulationof an acousticmedium. Less well known is the digital wave- surroundingsin the actualinstrument, is recognizablythe main determi- guidemodeling approach to the sameproblem, which is basedon simu- nantof the soundspectrum radiated from the instrument. latingthe propagationof sampledtraveling waves in the medium,and whichimplements losses and dispersion using digital filters applied to the 11:45 travelingwaves [Comput. Music. J., 74-91 (Winter1992)]. It turnsout the two methodsare equivalent in rectilinearcoordinates in one,two, and three $aMUll. Discrimination of musical chord components. BarbaraE. dimensions,in the lossless,nondispersive case, provided the spatialsam- Ackerand Richard E. Pastore (Dept.of Psych.,SUNY, Binghamton,NY plinginterval is chosento bea specificconstant (c in theone-dimensional ! 3902) case)times the temporalsampling interval. Since the digitalwaveguide The currentstudy uses an accuracyversion of the Gamerparadigm to simulationtechnique requires far less computational effort, it canbe used evaluatethe natureof the rolesplayed by the E andG frequenciesin the to bothaccelerate and increase the accuracy of numericalsimulations of acoustic media. pemeptionof rootposition C majortriads. Triads differed in theE and/or G frequencies,relative to anequal-tempered triad (prototype, or P set)or an out-of-tunetriad (nonprototype, or NP set).Thus, the P stimuliwere 11:15 morerepresentative of major chords than the NP stimuli.Significant re- dundancygains and interference effects were found for both frequencies in 5aMU9. Qualitativeand quantitativenonlinear dynamics of clarinet bothcontexts, thus demonstrating the components to be integral,as might tones and multiphonics. TeresaD. Wilson and DouglasH. Keefe be expectedfor tuningbased upon intervals. The amountof redundancy (SystematicMusicol. Program,School of Music DN-10, Univ. of gainfound was dependent on thetype of correlation,with thenegatively Washington,Seattle, WA 98195) correlatedstimuli experiencing a greater redundancy gain than the posi- Nonlineardynamics offers a nontraditionalbut usefulviewpoint from tivelycorrelated stimuli. Finally, better overall discrimination was found in whichto studytone production in theclarinet, and its applications have not the P context,thus replicating previous work [Acker,Pastore, and Hall, beenfully explored. A qualitativeand quantitative analysis using nonlinear Percept.& Psychophys.(in press)]showing that a prototypefunctions as a dynamicswas done on pressuretime series for single(monophonic) and perceptualanchor. In addition,major chord prototypes appear to be located multiphonictones performed by a professionalclarinetist. The pressure in thephysiologically motivated area of justtemperament, as opposedto wasmeasured by a piezoresistivepressure transducer inserted flush with themore experientially defined area of equaltemperament. [Work sup- theinner mouthpiece wall4.5 cm from the tip. Phase portraits and Poin- portedby AFOSR.] 3391 J. Acoust.Soc. Am., Vol. 97, No.5, Pt. 2, May1995 129thMeeting: Acoustical Society of America 3391 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp SATURDAY MORNING, 3 JUNE 1995 MEETING ROOM 2, 8:00 TO 10:20 A.M. Session 5aNS Noise: Community Noise and Flow Noise Louis C. Sutherland, Chair 27803 LonghillDrive, RanchoPalos Verdes,California 90274 Chair's Introduction--8:00 ContributedPapers 8:05 8:35 5aNSI. Modeling urban noisepollution as an architecturalacoustics SANS3.Texas highway noise barriers•The good, the bad, and the problem. GregoryA. Miller (Mech.Eng. Dept., The CooperUnion for ugly. Ilenc Busch-Vishniac,Steve Ho (Dept.of Mech.Eng., Univ. of the Advancedof Science and Art, Cooper Square,New York, NY Texas,Austin, TX 78712), RonPeron, and Michael McNerney (Univ.of Texas,Austin, TX) 10003-7183) and Daniel R. Raichel (The Cooper Union and the GraduateCenter of the City Universityof New York) Until recently,Texas has managedto avoid extensiveuse of highway noise barriersfor roadway noise mitigationin residentialareas. In recog- The problemof urbannoise pollution can almostbe consideredas an nition of the growing noise problem,particularly in the urban areasof architecturalacoustics problem. City blocksare treatedin a mannermath- Texas,the TexasDepartment of Transportation(TxDOT) is supportinga 3-year project aimed at producinga highway barrier design guide. In ematicallyanalogous to thea•oustics of rooms.Six New Yorkcity blocks additionto acousticalperformance, the designguide will considerissues were selected--chosenfor their varyinggeometries, materials, and traffic such as barrier supportand aesthetics.This talk will review the barrier patterns--andmeasurements of L•q were taken during one-hour periods project,concentrating on the first phaseof the work which has beento usinga type I soundlevel meter.This is an experimentin progresswith documentand evaluate the existing barriers in Texas.[Work supported by evenmore data to be accumulatedfor furtherrefinement of the theory.The TxDOT.] soundlevels producedby varioussources in theseblocks are found by measuringaverage traffic flow, pedestriantraffic, etc. Predicativenoise 8:50 levelequations (based on the sound level from a pointsource) are being generatedon the basisof the physicalcharacteristics of each block, and SANS4. Sonic boom as possiblemechanism of the-low-frequency will be reconciledwith experimentaldata to formulatecharacteristic equa- hum. Victor V. Krylov (Ctr. for Res. into the Built Environment, tionsthat shouldaccurately predict the soundpressure levels which ob- NottinghamTrent Univ., Burton St., NottinghamNG1 4BU, UK) serversare subjectedto. It is anticipatedthat the alterationof the absorp- The problemof disturbinglow-frequency noise, also called low~ tioncoefficients of thestructures lining the blocks will constitutethe major frequencyhum, has been knownfor at leasttwo decades.However, in factorwithin the reconciliation. The results of thisexperiment can in time many aspectsthe natureof low-frequencyhum still remainsa mystery be usedto encouragewiser materials choices and more careful plhnning in (see,e.g., "The Independent"of 22 June1994). It maybe possiblethat in future urbandevelopment. somecases the sourcesof this hum are undergroundg•s or petrol pipes whereturbulent flows of gasor liquid generatesound waves of high am- plitude propagatingin a pipeline as in a waveguide.The velocitiesof soundC o insidethe pipes (450 m/sfor methane)sometimes may be higher than the velocitiesof Rayleighsurface waves C n in the groundat the frequenciesof interest(5-50 Hz). Typicalvalues of Cn are300-600 mls. If so, i.e., if Co>C n , then groundRayleigh waves might be effectively 5aNS2, Noise barriers with random edge profiles. SteveHo, Ilene J. generatedby soundwave propagatinginside the pipes,the mechanismof Busch-Vishniac,and David T. Blackstock (Dtpt. of Mech. Eng., generationbeing similar to thatof a sonicboom from supersonic jets. Universityof Texas,Austin, TX 78712-1063) Preliminarycalculations show that central frequencies of generatedRay- leighwave ground vibration spectra depend on depth of thepipe and are in the low-frequencyrange. The amplitudesof generatedground vibration In normaldesign the top edgeof a noisebarrier is straight.As a result, velocitydue to soundwaves propagating in gas pipes buried at a depth of noise diffractedfrom the barrier edge seemsto come from a string of 2 m canbe around 70' dB (relative to 10-9 m/s).This may be enough to highly correlatedpoint sourc•a, that i•, a alxalghtlinc aource.Th• coher- annoysome people both because of directimpact of vibrationsand due to ence of the diffracted sound therefore limits the effectiveness of the barrier. generatedstructure-borne noise. One way to spoil the coherenceof the diffractedsound, and thus increase the barrier'sinsertion loss, is to vary the barrierheight by makingthe top 9:05 edgeirregular instead of straight.The radiationsfrom the pointsources at the edge then are not well correlated.We have conductedpreliminary $aN$5. Environmentalvibrations associatedwith high-speedtrains. experimentsusing physicalscale modelswith randomedge profiles.The Victor¾. Kxylov (Ctr. for Res.into the Built Environment,Nottingham spacingbetween height transitionsand the height variationmaxima are TrentUniv., BurtonSt., NottinghamNG1 4BLI, UK) scaledto thewavelength at whichthe sound source (a spark)has a peakin The dramaticrevival of railwaysin Europeto becomeone of the most itsspectrum. Results to dateshow significant improvement (3-8 riB)for a advancedand fast developingbranches of transportationtechnology may barrier with a randomedge profile comparedto one of the same average be comparedwith the spacetechnology breakthrough of the 1960s.The heightwith a straightedge. [Work supported by TxDOT.] reasonis high speedsachievable by the most advancedmodern railway 3392 J. Acoust.Soc. Am., VoL97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3392 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp trains,e.g., FrenchTGV trainsfor whicha maximumspeed of morethan gusts[H. Naumannand H. Yeh, ASME 1. Eng. Power12, 1-10]. The 515km/h was recorded in May 1990.Unfortunately, the increased speed of strengthsof thesegusts are determinedfrom the Fouriercoefficients of the railway communicationsis likely to raiselevels of associatedenvironmen- wake profiles.The soundwas then determinedfrom the unsteadyforce tal noiseand vibrationfar beyondthose significant even for conventional usinga concentratedforce radiation mechanism [N. Curie,Proc. R. Soc. railways.A review is given of recentprogress in the theoreticalinvestiga- LondonSet. A 231, 451-460 (1955)].The secondmethod used an incom- tion of groundvibrations generated by high-speedrailway traffic, with pressibleNavier-Stokes equationto predict the mean flow and unsteady emphasison problemsassociated with superfasttrains, i.e., trainstraveling pressuredue to the passageof the wakepast an airfoil. The resultingsound at speedsclose to or greaterthan 300 km/h. Significantincrease in ground was then determinedwith a Kirchhoff solver. The pressureand sound vibrationlevels (more than 70 dB) is predictedfor superfasttrains if they resultsfrom bothof thesemethods were comparedwith experimentaldata. travelat speedshigher than Rayleigh wave velocity in the ground[V. V. Kry!ov,J. Phys.IV, C5 4, 769-772 (1994)].Attention is paidto establish- [H. Fujitaand L. S. G. Kovfisznay,AIAA J. 12, 1216-1221(1974).] ingrelations between parameters of theproblem, e.g., geometrical dimen- sionsof trackand train,layered structure of the ground,train speed,etc., that could result in direct reductionin groundvibration generation effi- ciency. 9:50 9:20 5aNS8. Sound due to flow through a nozzle with time-dependent throat area, Paul R. Moran and David Swanson (Acoust.Program, 5aNS6. Application of computationalfluid dynamics (CFD) to Appl.Res. Lab., Penn State Univ., P.O. Box 30, StateCollege, PA 16804) automobilewind noisesource minimization. Keng D. Hseuh,Sanjay Abhyankar,Sanjeeva Addala, Anant Kamat, Chun Wu, and Mike P. Haffey (VehicleWind Noise& RoadNVH Dept., Core & Adv. Veh. An unsteadycompressible Euler code was developed for flow through SystemEng., MD 45-Adv. Eng. Ctr., FordMotor Co., 20000 RotundaDr., a nozzle.Method of characteristicboundary conditions were usedto per- Dearborn,MI 48121-2053) mir theunsteady pressure to be nonzerodownstream of theexit boundary. The flow is perturbedby modulatingthe cross-sectionalarea in the mid- Wind noiseis becominga critical comfortrequirement to customers sectionof the nozzle.The far-fieldunsteady pressure was determinedfor due to greatly reducedpowertrain and road noise, particularlyat high- both steadyand unsteadyinlet velocitiesand comparedto experimental speeddriving conditions. The physicalphenomenon generally can be cat- results. egorizedinto: sources (A-pillar vortex and mirror wake) and path (door/ window weatherstrip leakage). Two different vehicle greenhouse geometriesthat produce attached- and vortex-flow, respectively, were used in thisA-pillar vortex minimization case study to correlatethe CFD pre- dictedA-pillar vortex size and sidegl•s pressure distribution (Cp) with 10:05 measurementsfrom wind tunneltesting. A-pillar vortexand pressure dis- tributionhave been shown to be key factorsaffecting wind noise excitation 5aNS9.An experimental andcomputational studyof fundamental on sideglassand shape-inducedaerodynamic suction force on door/ reactive silencersin the induction system of firing spark-ignition window(which is requiredin designingdoor/weatherstrip to prevent as- engines.A. Selamet(Dept. of Mech.Eng. and Appl. Mech., 120 W. E. pirationleaks through weatherstrip under high-speed condition), respec- LayAutomotive Lab., Univ. of Michigan,Ann Arbor, MI 48109-2121)and tively. Resultsdemonstrate that the CFD can successfullypredict the J. M. Novak (FordMotor Company, Dearborn, MI 48121) effectsof geometrychanges on A-pillar vortex size and Cp within>80% accuracyunder various speeds/yaw angles. This studyconfirms that CFD canbe appliedwith confidenceas an upfrontengineering tool to optimize Thepresent study investigates the performance of fundamentalreactive vehiclegreenhouse geometry forminimum wind noise excitation ina cost silencerssuch as expansionchambers and Helmholtzresonators in the and time effective manner. presenceof bothhigh-amplitude pressure waves and oscillating fluid flow. The silencersare installedin the inductionsystem of a Ford 3.0-LiterV6 9:35 Vulcanengine in a dynamometertest facility. The experimentswith the firingengine have been conducted with speedsranging from 10013to 5500 SANS7.Numerical and analytical investigationof unsteadylift and rpm.Measurements including the meanflow rate,the temperatures,and sound due to airfoil-wake interaction. Paul R. Moran, Donald' E. the absolutedynamic pressures of the inductionair beforeand afterthe Thompson,and David Swanson (Acoust. Program, Appl. Res. Lab., Penn silencerwith fast-response, piezoresistive transducers facilitate the calcu- StateUniv., P.O.Box 30, StateCollege, PA 16804) lationof acousticand flow performanceof theseelements. A nonlinear Thepassage of anairfoil through a wakeis a dominantsource of noise computationalfluiddynamics method isthen employed inthe time domain in low Mach number flows. In order to examine this phenomenon,two for the predictionof noisereduction and insertion loss'characteristics of predictionschemes were used. The firstwas a thinairfoil analysis used to thesesilencers. The studyis concludedwith comparisonsof thesepredic- predictthe unsteady lift responseto sinusoidaltransverse and longitudinal tionsto the experimentalresults from the enginedynamometer facility. 3393 J. Acoust.Soc. Am., Vol.97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3393 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp SATURDAY MORNING, 3 JUNE 1995 RENAISSANCE WEST A, 7:45 TO 11:50 A.M. Session 5aPA PhysicalAcoustics: Surface Waves and InhomogeneousMedia Donald W. Brill, Chair PhysicsDepartment, U.S. Naval Academy,Annapolis, Maryland 21402 Chair's Introduction--7:45 ContributedPapers 7:50 Significantvariations of the phasevelocity were found for valuesof the roughnesswhich are smallcompared to the shortestof the wavelengths 5aPAI. Surface acoustic wave investigation of phase transitions in involved in the scattering.Similarly, the dispersionrelations showed con- YBa2CuaO?_s films..!. Feller,C. Hucho,R. Gaffhey,M. J. McKenna, siderablesensitivity to changesin mechanicalproperties typical of mate- B. K. Sarma, and M. Levy (Dept. of Phys., Univ. of Wisconsin, rialsof engineeringinterest. In the low-frequencyrange, on the otherhand, Milwaukee, WI 53201) simulationsillustrated the dispersionof Rayleigh waves to be rather in- Pulsedsurface acoustic waves (SAW's) at 165 MHz are usedto study sensitiveto thespectral content of theprofile. [Work performed within the the superconductingtransition and an apparentstructural phase transition LINK Projecton Characterizationof Surface and Sub-Surface Damage.] in filmsof YBa2Cu307_• (YBCO). The structuralphase transition occurs in the temperaturerange 200-230 K and is evidencedby largechanges in 8:35 SAW attenuationand velocity.Small changesare alsoseen at the super- conductingtransition temperature. These changes are markedlydifferent 5aPA4. Relation between the damping coefficientand the excitation whena conventionalconductor (e.g., copper) is broughtinto closeprox- coefficientof leaking Lamb waves. M. Ech Cherif El Kettani, F. imity to the YBCO film. The resultsof this investigationare in agreement Luppr,J. M. Conoir,and J. Ripoche (L.A.U.E.,U.R.A.C.N.R.S. 1373, with the hypothesisthat YBCO is piezoelectricbelow the 200 K transition. Univ. du Havre,pl. R. Schuman,76610 Le Havre,France) [Thiswork was supported by theOffice of NavalResearch, with C. Hucho supportedby DeutscheForschungsgemeinschaft.] The relationbetween the leakingability and the excitationcoefficient of a propagatingLamb wave on an immersedplate is studied.The morethe Lamb wave radiatesduring its propagation,the more stronglyit is ex- 8:05 pectedto be excited from the incidenceof an ultrasonicbeam at the appropriateangle. The excitationcoefficient of a given Lamb wave at a 5sPA2. Acoustic resonances in square cross-sectional rods given frequency-thicknessproduct is obtainedfrom a residuecalculation. (prelindnaryresults). JeromeBeige and Michel De Billy (G. P.S. It is numerically achieved from the exact formulation of the reflection Univ. Pads VI and VH, Tour 23, 2 Place Jussieu, 75251 Pads Cedex 05, coefficient,and analyticallyperformed with the help of the resonance France) scaueringtheory approximations. Both methods exhibit clearly the propor- As it wasobserved, it is shownthat for particularfrequencies, a square tionalityof the excitationcoefficient with the normalizeddamping coeffi- crosssection normally insonifiedgives rise to resonancephenomenon. cient.The directmeasurement of the excitationcoefficient is not possible This is illustratedby usingtwo differentacoustic approaches: a dynamic becauseof the interferencephenomenon of the Lamb wave radiationwith visualizationof the pressurescattered by a squarebar anda measurement the specu!arlyreflected beam. Consequently, the measurementsare per- of the reradiatedacoustic pressure in a planenormally oriented to the axis formedfar away from the interferencearea. The linearityof the pressure of a squarerod. Different structuresof the angularpatterns are observed amplitude(in dB) with thepropagation distance allows the direct determi- accordingto the natureof theexcited guided mode. The experimentswere nationof the dampingcoefficient, as well as the extensionof the experi- performedon specimensof differentmaterials such that the valueof the mental data to the interference area. The excitation coefficient is herefrom productof the frequencytimes the width of the rod is lessthan 28 MHz deduced.The resultsconfirm the theoretical ones. [Work supported by D. min.A theoreticalapproach based on theFraser's work [W. B. Fraser,lnt. R. E. T., France.] J. SolidsStructures 5, 379-397(1969)] will beproposed. 8:50 8:20 5aPA5. Geometrical theory of diffraction applied to Scholte wave 5aPA3, Acousticmicroscopy and dispersionof leaky Rayleigh waves diffraction. H. Duflo, A. Tinel, and J. Duelos (Lab. d'Acoustique on randomly rough surfaces:A theoretical study. Claudio Pecorari Ultrasonoreet d'Electronique,U_R_A. C.NI.R.g_ 1373, Unlversit• du andG. A.D. Briggs (Dept.of Mater.,Oxford Univ., Oxford OX1 3PH, Havre, Place R. Schuman,76610 Le Havre, France) UK) The geometricaltheory of diffraction(GTD) hasbeen established by A theoreticalinvestigation of the dispersionof leaky Rayleighwaves Keller in order to describe the interaction of a bulk wave with a dihedral propagatingalong one-dimensional, rough, fluid-solid interfaces was car- edge. It was experimentallyverified that Keller's laws were also valid to tied out by simulatingthe measurementprocess of a line-focusacoustic describethe interactionof a Scholtewave with the edge of an elastic microscope.The interfaceprofiles were describedin termsof their rms, dihedral.When the Scholtewave met the dihedral at obliqueincidence, the also known as the roughnessof the profile, autocorrelationlength, and diffractedenergy was actually on Keller'scone the axis and generatrix of autocorrelationfunction. Theoretical V(Z) curves were obtained and ana- it were respectivelythe dihedraledge and the directionof the incident lyzedto y!eldvalue• of thephase velocity of theRayleigh waves. The Scholtewave. It wasassumed that incidentenergy •pread among a bulk reflectivityof the interfaceswas calculated by usinga second-orderper- wave in the direction of the incident Scholte wave as well as reflected and turbationapproach in the profileroughness. The dependenceof the Ray- transmittedsurface waves (Scholte and Rayleigh waves). The direction of leighwave velocityon the profileand material parameters was examined. emission of these waves was calculated as a function of dihedral and 3394 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3394 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp incidenceangles. This calculus showed that Rayleigh waves did notexist numericallyto drawthe dispersioncurves. The low- andhigh-frequency if the incidenceangle was higher than the Rayleighangle. Experimental limits are calculatedanalytically. Special attention is devotedto the deter- resultswere obtained for duraluminumdihedrals of variousangles ranging minationof thecut-off frequencies. An asymptoticanalysis shows that, in from 30 to 90 deg and for incidencedirections between 0 and45 deg. mostcases, a doublingof the classicalLamb waveshappens. The small Diffractedenergy was only notedon Keller'scone. [Work supported by deviationof the cut-offfrequencies from the classicalones has been evalu- D.R.E.'E] ated. An additional,single mode is also outlined;its cut-off frequencyis smallerthan the Lamb wavesones and depends heavily on the waterfilm thickness.The experimentshave beenperformed on 3- and 5-mm alumi- 9:05 num platesinsonated at normalincidence by shortpulses. The reflected 5aPA6. Acousticscattering from finite length cylinder boundedby signalis then FFF-processed;depending on whetherthe specularecho is two sphericalendcaps. J. Carnet,a}J. Dujardin,D. D•cultot,and G. removedor not, a resonanceor a backscatteredspectrum is obtained.The Maze (LAUE URA CNRS 1373, Universitddu Havre, Place Robert doublingof the Lamb waves, and the existenceof an additionallow- Schuman,76610 Le Havre, France) frequencymode, have been thus confirmed. For a structurecomposed of threealuminum plates, the experimentnow outlinesfamilies of threemod- The acousticscattering from finite cylindricalobjects endcapped by els, eachfamily beingclosely related to one classicallamb wave. two hemispheresis studied.To explain the experimentalresonance spectra when the objectis parallellyinsonified to the axis, a conditionof phase 9:50-10:05 Break matchingis written on the meridiancircumference. To apply this condi- tion, it is necessaryto know the phasevelocity of surfacewaves along the differentparts of the object.To verify this hypothesis,resonance identifi- 10:05 cationsare realized.The identificationdiagrams are not easyto interpret. The lobe numberis not equal to the antinodenumber, and theselobes do 5aPA9. Acoustics of fluid conveying elastic structures. Michael A. not have the sameamplitude. An integralmethod will permitthe knowl- Grinreid and Andrew N. Norris (Dept. of Mech. and Aerosp.Eng., edgeof the acousticpressure in the far field if the profileof the vibration RutgersUniv,, Piscataway, NJ 08855-0909) statealong the meridianline is sinusoidal.A good agreementis obtained Acousticwaves are consideredthat are propagatingin a layeredstruc- betweenthe theoreticaland experimentalstudies. To confirmthis hypoth- tureconsisting of elasticlayers with ideal fluid movingbetween them. This esis,a finiteelement method is developed.A 2-D problemis considered.A is a simplemodel of a fluid-filledporous medium. First discussedis the meridianplane and the water aroundthe objectis meshed.A sinusoldburst dependenceof the dispersioncurves on the relative velocity of the fluid with severalperiods insonifies the object.The vibrationamplitude of the and on the materialand geometricalparameters of the constituents.Dis- surfaceof the object is determinedin every way. The resultsconfirm the persionrelations for a periodiclayering are derivedexplicitly. Different hypothesisused in the integralmethod and allows the validationof the asymptoticlimits can be obtained,which reduceto known solutionsfor phase-matchingcondition. a)ln memory to J. Carnet deceased inJune 1994. interfacialacoustical wave motion in the presenceof flow.The mainfocus of thistalk is the possibilityof instabilitiestriggered by the movingfluid in 9:20 the layeredsystem. The role of suchacoustical instabilities in nonlinear dynamicsof poroelasticfluid-filled media is discussed.This effectcan be 5aPA7, Acoustic scattering from a circular cylindrical shell excited viewedas a generalizedflutter phenomenon, made possible by the perme- by a short pulse in oblique incidence: Helical waves. G. Maze, J. M. abilityof the porespace. [Work supported by ONR.] Conoir,E L•on, andD. D•cultot (Laboratoired'Acoustiqu½ Ultrasonore ct d'l•lectroniqucURA CNRS 1373, Univcrsit• du Havre, Place Robert 10:20 Schuman,76610 Le Havre, France) 5aPAI0. Observation of seismic wave propagation in particulate The theoreticaland experimentalspectra, obtained from an infinite compositematerial with various inclusionsizes and concentrations. pipe insonifiedwith a plane wave in oblique incidence,show resonances Seiji Nakagawa,Neville G. W. Cook (Dept. of Mater.Sci. & Mineral whichare related to threetypes of helicalwaves: the circumferentialwaves Eng., Univ. of California,Berkeley, CA 94720), K.T. Nihei, and L. R. (Ai or Si waves),the transversal guided waves (T• waves),and the $cholte Myer (LawrenceBerkeley Laboratory, Berkeley, CA 94720) wave (A wave). The resonancesof the $cholte wave are detectedin a frequencywindow and their frequencyslowly increaseswhen the inci- Two-phaseparticulate composite samples with inclusionsof varying denceangle increases,whereas the onesof the other wavesincrease to- size and concentrationwere madewith cementand sandor pebbles.The wardsinfinity when the incidenceangle tends towards the transversalcriti- velocitiesof P-wave(60-kHz) andS-wave (150-kHz) pulses and the at- cal angle.At obliqueincidence, the experimental results obtained with the tenuationof S-wave pulseswere examined.The resultsof the tests sug- MIIR showresonances which are relatedto the helical wavesS O , T O, T•, gestedthat the velocitieswere consistent with the resultsof effectivemedia andA. This methoduses a long pulsewith many sinusoidperiods, a steady modelswhich were inclusionsize independent.However, the frequency- statetakes place in a part of the infiniteshell. In this presentation,the dependentattenuation of the S wave wasstrongly affected by the sizeof excitationis a shortpulse and the scatteredechoes arc detectedwhen the the inclusions.For inclusionssized on the orderof 1/10 of the wavelength, helical wave emission is in front of the receiver. Between each echo, the the wavesshowed decreasing attenuation with increasingconcentration, helicalwave hascovered one stepof the helix (L=2•'a/cos % a is the while for the sizesof about 1/4 and 1/1 of the wavelength,the waves outerradius of cylinder,y is theangle of thehelix). This methodallows us showed maximum attenuation at volumetric concentrations of about 30% to calculatethe group velocity of the helical waves. and 70%, respectively.Many aspectsof the observedwave behavior for moderate concentrations were similar to numerical simulations of I-D 9:35 wave propagationin a layeredmedia, where the matrixand inclusions wererepresented by alternatinglayers with different seismic properties and 5aPA8. Lamb waves of two elastic plates coupled by a thin water stochasticallyvaried thicknesses. [Work supported by NSF.] film. M. Rousseau,E Coulouvrat (Laboratoirede Mod61isationen M6canique,Universit• Pierre et MarieCurie et C.N.RS. (URA 229) Case 10:35 162, 4, placeJussieu, F-75252 ParisCedex 05, France), O. Lenoir,H. Khelil, and J. L. Izbicki (Univcrsitfidu Havre and C.N.R.S. (URA 1373) 5aPAll, Flow resistanceof fibrousmaterials, ViggoTamow (Dept.of F-76610 Le Havre, France) Appl.Eng. Design and Production, Danish Technical Univ., Bygning 358, DK 2800, Denmark) This experimentaland theoretical study investigates the guidedwaves thatpropagate along a multilayeredstructure, composed of two identical, It is of interestto be able to computethe acousticalproperties of infinite,aluminum plates coupled by a thin waterfilm. The relateddisper- fibrousmaterials from the fiberdensity and thicknessof materialssuch as sion equationis written undera closedform. Solutionsare calculated glasswool. These properties are mainlydetermined by the air flow resis- 3395 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3395 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp tance of the fibrous material. Theoretical calculations of air flow resistance the choiceof a setof dependentvariables in hydrodynamicequations for will be presentedand compared with measurements on glasswool. describingthe wave field. An implicationof the FRT on wave action conservationfor cw soundin movingfluid is considered.Some possible 10:50 FRT applicationsare indicated. [Work supported by NRC.] 5aPA12. Guided sound propagation in three-dimensional 11:20 inhomogeneousmoving nonstationary fluid. OlegA. Godin (NOAA/ 5aPA14. Measurements of Blot type I and type lI waves in an AtlanticOceanogr. and Meteorol. Lab., 4301 RickenbackerCswy., Miami, air-filled packing of sand. Craig J. Hickey and JamesM. Sabatier FL 33149) (Natl. Ctr. for Phys.Acoust., Univ. of Mississippi,University, MS 38677) Soundpropagation in a multicomponentfluid, passmetersof which The interpretationof acousticand seismic measurementsin porous includingflow velocityas well as shapeof boundariesare smoothand materialsare usuallycarried out usingthe Blot theory.This theorypredicts slowlyvarying functions of time andtwo horizontalcoordinates, is con- the existenceof two P waves(referred to hereas typeI andtype II) and sidered.No limitationsare imposedon the Mach numberand the fluid one S wave.The type I P wave is predictedto have small dispersionand parametersdependence on the verticalcoordinate other than the assump- attenuation.The type IIP wave is predictedto .be dispersiveand highly tionthat sound/flow synchronism points axe absent. All theprocesses in the attenuating.An experimentis carriedout wherebyair bornesound is in- fluid are assumedto be adiabatic.The methodof two-scaleexpansions is cidentupon an air-filledpacking of sand.For sucha configuration,a large usedto constructasymptotic development of solutionsof the setof hydro- proportionof the transmittedenergy is partitionedto the type II P wave. dynamicequations linearized with respectto the wave'samplitude. The However,due to the high attenuationof the type rl p wave this energy well-known"vertical modes-horizontal rays" approachis generalizedto shoulddecay rapidly nearthe surface.Measurements using a probemicro- coveracoustic waves in nonstationarymoving media. An adiabaticinvari- phoneapparatus, in-situ microphones, and in-situgeophones are obtained ant is foundthat governsthe amplitudevariation of a normalmode along in the frequencyrange of 500-3000 Hz. The in-situ microphonesand the correspondingspace-time horizontal ray. Physical meaning of the adia- geopbonesextend to a depthof 40 cm belowthe surfacein an attemptto baticinvariant is analyzed.Results are compared to thoseof recentstudies detectthe TypeI P wave.Attenuation and phasevelocity of the air-filled of guidedpropagation in movingtime-independent [O. A. Godin,DAN packingof sandis determinedas a functionof depthfrom thesemeasure- SSSR320, 204-208 (1991)] and unstationarymotionless fluid [A. V. ments.[Work supported by USDA.] Aref'evand V. S. Buldyrev,Akust. Zh. 40, 205-211(1994)]. The impor- tanceof a consistentaccount of medium'smotion and its timedependence 11:35 is demonstrated.[Work supported by RBRFand NRC.] 5aPAI5. Simulation of wave propagation through an inhomogeneous 11:05 turbulent medium with the aid of an integral formulation. HirobumiKaneko (130C Olde DerbyRd., Norwood,MA 02062) 5aPA13. Reciprocity-type relations for waves in a moving inhomogeneousfluid. Oleg A. Godin (NOAA/AfiamicOceanogr. and A propagationsimulation algorithm is describedwhereby, at the be- Meteorol.Lab., 4301 RickenbackerCswy., Miami, FL 33149) ginning of step n, the pressureassociated with a progressivewave is specifiedas a functionof time andlateral position along a planarsurface, The reciprocityprinciple is knownto be invalidfor acousticwaves in x=x.. The algorithmfor stepn yields the pressureas a functionof time a movingfluid due to differencesin up- and down-flowwave propagation and lateralposition at x=x.+ •. The basicmathematical formulation em- velocities.A variationof the reciprocityprinciple, a flow reversaltheorem ploysan integralequation that predictsthe waveformsat arbitraryposi- (FRT), whichstates symmetry of somefield quantitywith respectto in- tionsto theright of thefirst surface. The medium between the point and the terchangeof the sourceand receiver positions and the simultaneous rever- surface,x=x•, is turbulent.The integralover the surfaceinvolves the sal of flow, was consideredby many authorsduring the last four decades. Green'sfunction for a pointsource in the actualmedium. Although the It was provenunder that or otherspecific assumptions about fluid param- exactGreeu's function is extremelydifficult to compute,it is arguedthat a etersand/or flow velocityspace dependence or in a frameworkof some goodapproximation for moderatestep sizes, Ix•-I-Xnl, resultsif the asymptoticrepresentations of the acousticfield. A simplebut rathergeneral Grcen'sfunction is takento be that which resultsfrom a ray-aooustics proof of the FRT will be presentedwhich is valid for soundas well as approximation.Moreover, because the first causticfor a point source acoustic-gravitywaves in an arbitrarythree-dimensional inhomogeneous Green'sfunction is notencountered for a distanceconsiderably longer than movingfluid with time-independent parameters provided divergence of the the distancebetween successive caustics for a nominallyparallel group of flow velocity is zero. The fluid may be unboundedor have pressure- rays within a ray tube, the difficultiesof explicitlytaking causticsinto release,rigid, or impedanceboundaries. The key point in the approachis accountis circumventedwith this algorithm. 3396 J. Acoust.Soc, Am., VoL 97, No.5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3396 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp SATURDAY MORNING, 3 JUNE 1995 AUDITORIUM, 8:30 A.M. TO 12:10P.M. Session 5aPP Psychologicaland PhysiologicalAcoustics: Cortical Representation and Processingof AuditoryStimuli Eric D. Young,Chair JohnsHopkins School of Medicine,505 TraylorBuiMing, 720 RutlandAvenue, Baltimore, Maryland 21205 Chair's introduction-•8:30 Invited Papers 8:35 5aPP1.Functional organization and reorganization of primaryauditory cortex. ChristophE. Schrcincr(Coleman Mem. Lab., W. M. Kcck Ctr. for IntegrafiveNeurosci., Dept. of Otolaryngol.,Univ. of California,San Francisco, CA 94143-0732) Neuronsin primaryauditory cortex (AI) of catsand monkeys have a widerange of functionalproperties that are related to the codingof basicattributes of simpleand complexsignals. In particular,cortical neurons have been found to be sensitiveto the bandwidthof the signal,the spectralenergy distribution of broadbandstimuli, the overallintensity of the signal,and the temporal sequenceof signalelements, in additionto theirfrequency selectivity and sound localization sensitivity. These response properties appearto be nonuniformlydistributed across AI and,thus, create spatially and functionally distinct subregions that may constitute parallelauditory processing streams. Studies with behaviorally trained animals suggest that these functional cortical organizations are notfixed but can undergo changes. This representational plasticity results in moredetailed representations of portions of theanimal's acousticenvironment that have high behavioral relevance. An understandingof the creation,relationships, and interconnections of thesedifferent coding properties is essentialfor thecomprehension of the neural code of communicationsounds such as speech. [Work supportedby the Officeof Naval Research,the HumanFrontier Science Project, and the ColemanFund.] 9:15 5aPP2.Representation of the acousticspectrum in the primary auditorycortex. ShihabA. Shamma(Elec. Eng. Dept. and Inst. for SystemsRes., Univ. of Maryland,College Park, MD 20742) A fundamentalgoal in auditorycortical physiology has been to understandhow the spectral profile is representedin thefiring rate of corticalcells. Recent experimental findings shed light on twobasic properties of thisrepresentation in AI: (1) Responsesto sounds with broadbandspectra (such as speechand most environmental sounds) superimpose linearly. Thus if a complexarbitrary spectral profileis viewedas composed of elementaryspectral profiles, then AI responsesto sucha profilecan be reconstructedfrom the sum of the responsesto thesesimpler elementary profiles. This seemsto be trueboth for stationaryand dynamic spectra. (2) AI unitsare rather selectiveto the spectraland temporalparameters of the acousticprofile. Specifically,when testedwith elementaryspectral profilesthat are sinusoidally shaped against the logarithmic frequency axis (or socalled rippled spectra), and that slide against this axis at variousvelocities, AI unitsare foundto be tunedaround different ripple densities, ripple phases,and ripple velocities.The above two findingssuggest that AI performsa Fourier-likeanalysis of the spectralprofile into a compositeof weightedsinusoidally shaped spectra(ripples). Such an analysisis analogousto thatof visualscenes found in the primaryvisual cortex (VI). 9:55 5aPP3.Processing of complexsounds in rhesusmonkey auditory cortex. loserP. Rauschecker(Lab. of Neuropsych.,NIMH, Bldg. 49, Rm. lB80, Bethesda,MD 20892-4415) Severalauditory fields surrounding primary auditory cortex (AI) havebeen described in therhesus monkey. Most recently,three areashave been identified in theso-called auditory belt region on the lateral surface of thesuperior temporal gyrus [Rauschecker et al., Science(1995) (in press)].Functional identification of theselateral areas (AL, ML, andCL) wasbased on singleunit responsesto bandpassednoise (BPN) bursts, which constitute a class of superiorstimuli for neuronsin thisregion. Best center frequency (BFc) of the BPN burstsvaries systematicallyalong a rostro-caudalaxis, revealing three cochleotopicmaps. Neurons in the lateral areas also displaytuning to a "bestbandwidth" of the noisebursts, which varies along a roerio-lateralaxis, orthogonal to theBFc axis.Digitized vocalizationsfrom the rhesusmonkeys' own repertoirewere finally used for presentationduring single-unitrecording. In many instances,neurons responded even betterto the monkeycalls than to noisebursts or othersynthetic stimuli. It appearsthat the lateral belt areasof macaqueauditory cortex could form an importantstep in the preprocessingof species-specificcommunication sounds, somewhatequivalent to superiortemporal areas in humansthat havebeen implicatedin phonologicalprocessing. 3397 d. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3397 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 10:35-10:50 Break 10:50 5aPP4. Elevationsensitivity in the cat's thalamo-corticalauditory system:Role of monaural spectraland binaural disparity cues. ThomasJ. lmig, PierrePokier, and Frank K. Samson (Dept.of Physiol.,Kansas Univ. Med. Ctr.,3901 RainbowBlvd., Kansas City, KS 66160-7401) High-frequencyneurons in auditorycortex (AI) androedial geniculate (MGB) of anesthetizedcats are differentially sensitive to monauraland binaural directional cues present in broad-bandnoise. Binaural directional (BD) cellsdepend upon binaural stimuli for azimuthsensitivity, whereas monoaural directional (MD) cellsare sensitive to thedirection of monauralstimuli. In theMGB, neurons' spatialreceptive fields (SRFs) were obtained using noise bursts presented throughout the frontal henrifield and sound pressure levels that variedover an 80-dBrange. BD cellswere broadly tuned to elevation.Those that received excitatory input from oneear and exhibitedbinaural inhibition or mixedinteractions had SRFs that extended throughout one lateral hemifield. Predominantly binaural cells exhibitedstrong binaural facilitation and had SRFs that formed a verticalband in front of the head. MD cells' SRFs varied considerably,some were focal areas restricted in azimuthand elevation. Others consisted of multipleareas that in somecases showed level-dependentchanges in location.The elevationsensitivity of MD cellswas nearly identical under monaural and binaural conditions showingthat it derivedfrom monaural spectral cues. AI unitsshowed similar response properties. [Work supported by NIDCD.] 11:30 5aPP5.Cortical codesfor soundlocation. JohnC. Middlebrooks(Depts. of Neurosci.and Otolaryngol., Box 100244,Univ. of Florida,Gainesville, FL 32610), Ann ClockEddins (IndianaUniv., Bloomington, IN 47405), Li Xu, andDavid M. Green (Univ. of Florida,Gainesville, FL 32611) Theresponses ofauditory cortical neurons carry information both in thenumber of spikeswithin a burstand in thetiming of those spikes.The capacityof singleneurons to encodesound locations was studiedin areasAI and AES of a-chloralose-anestbetizedcats. The spikecounts of abouthalf of studiedneurons were modulatedby morethan 50% as a noisesource was variedin azimuth. Nevertheless,the "bestareas" of mostunits, using a 50%-of-maximum-responsecriterion, were larger than 180ø. Temporalspike patternsof singleneurons could be classifiedaccording to soundsource azimuth, using an artificialneuron network. The classification of temporalpatterns consistently surpassed a maximum-likelihood classification of spike counts. The spike patterns of singleneurons couldsuccessfully encode locations throughout 360 ø of azimuth.The localization performance of anysingle neuron was substantially worsethan that of an awake,behaving cat. When responses were averaged across multiple trials, however, performance improved monotonicallywith increasesin the numberof trials,suggesting that the information carried out by the temporalspike patterns of multiple neuronscould accountfor a cat's localizationbehavior. SATURDAY MORNING, 3 JUNE 1995 MEETING ROOM 16, 9:00 TO 11:30 A.M. Session 5aSA Structural Acoustics and Vibration: Plates and Shells II CourtneyB. Burroughs,Chair AppliedResearch Laboratory, Pennsylvania State University, P.O. Box30, StateCollege, Pennsylvania 16801 ContributedPapers 9:00 ticitysolution for the axisymmetric response of cylindricalshells. Results are presentedfor steel-likeand rubber-like wall materialsand compared 5aSA1.Transmission of turbulent boundarylayer pressuresthrough with resultsfrom thin shelltheory. thin and thick shells. JackCole (CambridgeAcoust. Assoc., Inc., 200 BostonAve., Ste. 2500, Medford, MA 02155-4243) 9:15 Turbulentflow alonga structuralboundary acts as a sourceof noiseto 5aSA2. Frequencydomain assessmentof the doubly asymptotic the interior space.Characteristics of the transmittednoise are determined approximation.Jerry H. Ginsberg(School of Mech.Eng., Georgia Inst. not only by the turbulentflow field but also by the transmissioncharac- of Technol.,Atlanta, GA 30332-0405) terisficsof the boundingstructure. In low-speedflow applications,the The mostwidely implemented technique for modelingfluid-structure spatial scale of the turbulence can be smaller than the structural wall interactioneffects associated with shock response is thedoubly asymptotic thickness.Under this circumstance, thickness effects are important in mod- approximation(DAA), which has been developed in a varietyof versions. elingthe wall transmissibility.These effects are examined using the elas- Analyticalvalidations of thismethod have thus far onlybeen performed 3398 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt.2, May1995 129thMeeting: Acoustical Society of America 3398 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp for sphericaland infinitelylong cylindrical shells. The presentwork uses 10:00 Nicholas-Vuillierme'sderivation [Numerical Techniques in Acoustic Ra- 5aSAS. The acousticalbackground for elastic shells of nonspherical diation,edited by R. J. Bernhardand R. E Keltie (ASME-NCA, Vol. 6, objects. M. F. Werby (Naval Res. Lab., StennisSpace Center, MS 7-13 1989)]of the frequency-domainversion of DAA as the basisfor 39529) and N.A. Sidorovskaia (Univ. of New Orleans,New Orleans, examiningthe accuracy and limitations of DAA for a slenderhemi-capped LA 70148) cylindrica{shell. The basicconcept is to useDAA to determinethe wet surfaceimpedance matrix relating surface pressure and velocity variables, The acousticalbackground for elasticshells which allows one to isolate whosev•ilues are comparedto thoseobtained from the surfacevariational elasticshell resonance's was first presented at an ASA conferencein 1989 principle(SVP) using the same set of basisfunctions. After such compari- for sphericalshells. A formulationhas been developed that is basedon the sonis made,the alternative wet surfaceimpedances are used to predictthe T-matrix methodgeneral for nonsphericalshells. An outlineof the formu- structuralresponse o• thehemi-capped cylindrical shell to a ringforce. lationis presentedand it's usein isolatingresonance's for elasticspheroi- Assessmentsfor frequenciesin the rangeka<10 for a shellwhose length dal shellsis presented.[Work sponsored by NRL andthe Office of Naval to diameterratio is L/2a =6 indicatethat DAA fails to recognizeeffects Research.] associatedwith transitionfrom supersonicto subsonicstructural waves. The implicationsof thisshortcoming for structuralresponse are discussed. [Workcupported by theOffice of NavalResearch, Code 1222.] 10:15-10:30 Break 9:30 10:30 5aSA3. Spiked volleyballs, dribbled basketballs, and kicked footballs: Excitation of the fundamental breathing mode in inflated 5aSA6. A new analytical approach for radiation problem from finite sportballs. DavidG. Browning (BrowningBiotech, 139 Old NorthRd., cylindrical piezoceramicshell. Victor T. Grinchenko (Dept. of Kingston,RI 02881), RobertH. Mellen (KildareCorp., New London, Hydrodyn.Acoust., Inst. of Hydromech.,Natl. Acad. of Sci., Kiev, 252057, CT 06320), RobertJ. Schneck,and Stephanie Milbradt (Univ.of Rhode Ukraine) Island,Kingston, RI 02881) The o,bjectiveof thispaper is to presenta completeanalytical solution The analysesof the soundfrom a hand-struckor "spiked"volleyball, fora finit'•piezoelectric cylinder radiation problem. Three aspects of the a "dribbled"basketball, and a place-kickedfootball show that in eachcase problemare discussed. (1) Developmentof a theoryof thinpiezoceramic shellswith hypothesesfor electricfield componentsthat are equivalentto the fundamental"breathing" vibrational mode is excitedin theseinflated sportballs. 0nder regulation conditions theresonant frequency ofa vol- theclassical Love's mechanical ones. (2) Explanationof a newanalytical approachto solve a coupledelastic-electric-fluid interaction problem. leyball was found to be approximately150 Hz; a basketball,which is The exact solutionfor the acousticpotential function is given in termsof largerbut has a higherinflation pressure, was found to have a slightly an infinite seriesof partial solutionsof the Helmholtzequation in cylin- higherfrequency. Due to the shellmaterial these vibration• are quickly dricaland sphericalcoordinate systems. The associatedcoefficients are the damped.The resultssupport the theoreticalwork [P.M. Morseand H. solutionof an infinitelinear system. A new approachto truncationof this Feshbach,Methods of TheoreticalPhysics (McGraw-Hill,,' New York, systemwhich takes into accountthe sharpedge effects, is developed.An 1953),p. 1469]for a hollow,flexible sphere. It wasfound that "good" hits estimationof the calculationaccuracy of the methodis presented.(3) stronglyexcite this mode,"poor" onesdo not.Acoustic analysis may be Numericalimplementation of the analyticalsolution for differentvalues of an importanttool in determiningoptimum performance. key parametersgives a groundto elucidatea complexexchange of energy betweenelectric generator, elastic structure, and surroundingfluid. Modi- ficationof eigenformsof the shell due to radiationin water is described. 9:45 5aSA4. An approximation to the local acoustic impedance of a 10:45 cylindrical shell with hemispherical endcaps. Michael J. Utschig,Jan D. Achenbach,and Takeru Igusa (Dept. of Civil Eng., Northwestern 5aSA7. Dispersion of longitudinal waves in periodic septate Univ., Evanston,IL 60208) liquid-elastic waveguides. L. Sbeiba (EG&G WASC, Inc., 1396 PiecardDr., Rockville,MD 20850) A methodhas been developed to approximatethe localradiation im- pedanceof a cylindricalshell with hemisphericalendcaps. This approxi- The propagationof longitudinalwaves m a compositeliquid-elastic mationgreatly reduces the effortrequired to calculatethe acousticimped- waveguideis analyzed.The waveguideis a periodicstructure consisting of alternatingliquid-elastic cylinders joined by rigid septa.The elasticma- ance as comparedto an approachusing a variational method. The terial(Lam6 constants: p,,•3., Poisson relation •0.5) andthe liquidma- approximatemethod uses the exact acousticimpedances of severalsepa- terial (/x=0, 0'=0.5) are assumedto havelow compressibility,and the rable geometricshapes to approximatethe acousticimpedance of a com- septaare rigid and weightless.Consequently, the boundarybetween the plex structurethat is a compositeof thoseshapes. The shellis brokeninto cylinder and the septum'sradial displacementis absent,and the axial three components:two hemispheresand a finite cylinder.These compo- displacementsareplanar. The fidmittance matrix Y of theunit cylinder is nentsare parts of regionsthat are separablein an orthogonalcoordinate initially constructedwithin a frameworkof the hypothesisof plane cross system.It is assumedthat the acousticimpedance of the componentsis the sections,neglecting strains induced by hydrostaticstress. Hydrostatic same as the acousticimpedance calculated exactly for the separable stresswaves are approximat½!yincluded by addingto the unit cylinder shapes.Furthermore, it is assumedthat the local acousticimpedance of the admittancematrix correction •Y associatedwith the strains of hydrostatic originalcomplex shape is the sameas thatof correspondingpoints on the stressin the cylinder.The transfermatrix of the liquid-elasticwaveguide simplecomponents. The accuracyis improvedwhen the interactionbe- and its elements,expressed through the waveguidesections elastic param- tweenneighboring components is considered.The acousticimpedance and eters,have been obtained. It hasbeen shown that •iamping in a waveguide surfacepressure generated by a lead appliedin the centerof the complex with a perigdicstructure is muchgreater in comparisonwith a regular shapeis comparedwith that calculatedusing a variationalformulation. waveguide,even when the latter is made with a high-lossmaterial. 3399 J. Acoust.Sec. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3399 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 11:00 11:15 5aSAS.Electroelastic modeling of the motionsof ceramicbars under 5aSA9. Investigation of the vibroacoustical characteristics of large driving voltages. M.C. D6kmeci (IstanbulTech. Univ.--Tcknik cylindricalshells. RostislavA. Dudnikand Andrei B. Kolpakov (Dept. Oniversite,P.K. 9, Taksim,80191, Istanbul, Turkey) and G. Aõkar of Phys.,Inst. Arch. Civil Eng., 65 II'inskayaSt., 603600 N.-Novgorod, Altay (Bo•aziqiUniv., Bebek, Istanbul) Russia) In relationto electroceramicmedia subjectto large driving voltages, thispaper presents the one-dimen3ionalnonlinear equations of a cylindri- Experimentaland theoreticalinvestigations of the influenceof inho- cal ceramicbar. The fieldvariables of theceramic bar areall expandedin mogeneityupon the oscillationsand radiation of thin cylindricalshells are thepower series expansions of itscross-sectional coordinates. By meansof executed.The inhomogeneityis presentedby eitherone additionalmass a unifiedvariational principle, which is formulatedthrough Hamilton's (m0) fastened(at •=180 ø) on the shellsurface, or two identicalinertia principleand Legendre'stransformation [e.g., M. C. D6kmeci,IEEE masses(m I = m2 = m0/2) whichare fastened at (1)= _+(I) l. Theimpact of Trans.UFFC 35, 775-787 (1988)]together with the series expansions of suchdivision of a unitinhomogeneity onoscillating velocity distribution fieldvariables, the one-dimensional electroelastic equations are systemati- aswell ason thepressure radiated levels and directionality diagrams of the callyderived in bothdifferential and variational forms. They are capable of relevantshell models is analyzedfor differentquantities of summarymass predictingthe extensional,flexural, and torsionalas well as coupledmo- (m0).The executionanalysis is limitedby the investigationof azimuth tionsof a ceramicbar at low andhigh frequenciesl By a propertruncation lower-frequencymodes. It wasshown that the considered distribution of of the seriesexpansions, the electroelasticequations incorporate as many inhomogeneitymakes it possibleto controlthe radiationlevel of the shell higher-ordereffects as deemeddesirable in any case. Specialcases are in certainfrequency ranges. The investigationof a structureof nearand far investigated[cf. M. C. Di3kmeci,Int. J. SolidsStmct. 10, 401-409 (1974) acousticalfields radiatedby these shells at various distancesfrom the and Proceedingsof the 40th Annual Symposiumon FrequencyControl radiating surfaceswas conductedalso. It was shownthat as this distance (IEEE, New York, 1986),pp. 168-178]. The uniquenessis examinedin increases,the number of themode providing the largest contribution tothe solutionsof thelineadzed electroelastic equations. [Work supported in part completefield decreases.Corresponding experimental results are pre- by The Scientificand Technical Research Council of Turkey.] sented. SATURDAY MORNING, 3 JUNE 1995 RENAISSANCE WEST B, 9:00 A.M. TO 12:00 NOON Session 5aSC SpeechCommunication: Articulatory Modelsand Measurements Maureen L. Stone, Chair Divisionof Otolaryngology,HNS, Departmentof Surgery,University of Maryland,School of Medicine,Baltimore, Maryland 21201 ContributedPapers 9:00 9:15 5aSC1.Is intra-articulatorspeech coarticulation planned? David1. 5aSC2. Recoveryof task-dynamicparameters with a mismatched Ostry (McGill Univ.,Montreal, PQ H3A 1BI, Canada)and VincentL. articulatorymodel. RichardS. McGowanand Mindy Lee (Haskins Gracco (HaskinsLabs., New Haven,CT 06511) Labs.,270 Crown St., New Haven,CT 06511) Doesthe nervoussystem take account of upcomingphonetic context A methodfor recoveringtask-dynamic parameters from speech acous- whenplanning successive movements of a speecharticulator? The kine- tics has beenproposed [see McGowan,Speech Commun. 14, 19-48 maticsof intra-articulatorcoarticulation are readily measurable in empiri- (1994)].In the seriesof teststo be describedhere, there were mismatches cal studiesand may appearto be centrallycontrolled on the basisof imposedbetween the task dynamics that produced the speech data and the kinematicchanges which arisein responseto upcomingphonetic seg- taskdynamics used in theanalysis-by-synthesis procedure for recovery. ments.However, without explicit models of speecharticulaters, measured kinematiceffects correctly attributable to centralplanning cannot be dis- Oneof themismatcbes was in thearticulator weights used in specifying tinguishedfrom the kinematicpatterns which ,ac ducit, dynamic•and me how muchof eacharticulator to usein attainingconstruction goals. An- other mismatch was in the allowed relation between activation interval and notrepresented in the underlyingcontrol. In thepresent paper, this ques- tion is addressedby comparingthe resultsof empiricaland modeling thenatural frequency of •theconstriction dynamics (natural frequency con- studiesof jaw motion.The simulatedkinematics of sagittalplane jaw straint).Bilabial and velar places of articulation(constriction) were tested, rotation'and horizontal jaw translation are compared toempirical studies in andthe first threeformant trajectories were used as data.When therewas whichsubjects produce CVC sequencesat a normalrate and volume. The articulatorweight mismatching, it wasfound that articulaters Would com- jaw motionsimulations show that even when control signals underlying pensateso that the recovered constriction trajectories were similar to those theinitial CV transitionare fixed, "anticipatory" kinematic patterns vary of thedata producing trajectories. It appearedto be moredifficult to over- in amplitudeand duration as a functionof upcomingcontext. This suggests comemismatches in the natural frequency constraint. Also, the nonunique- that unplannedeffects due to articulatordynamics must be accountedfo3 nessof the recoveredtask dynamics is exhibitedwhen there is not suffi- before drawing conclusionsabout the role of central control in intra- cientacoustic data. [This work was supported by NINDCDGrant 01247 to articulatorcoarticulation. [Work supported by NIH GrantCD-00594.] HaskinsLaboratories.] 3400 d.Acoust. Sec. Am., Vol. 97, No. 5, Pt.2, May1995 129thMeeting: Acoustical Society of America 3400 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 9:30 respondingacoustics than coefficientsfrom ellher the nonorthogonaltwo- factorsolution or theorthogonally constrained three-factor solution. These 5aSC3,Influences of stopconsonant voicing on tongue,lip, and jaw threefactors also correspond qualitatively to the threenonorthogonal fac- movement kinematics. Anders L•fqvist and Vincent L. Gracco torsextracted from Icelandicx-ray film voweldata [Jackson, J. Acoust. (HaskinsLabs., 270 CrownSt., New Haven,CT 06511-6695) Soc.Am. 84, 124-1430988)]. Thusthe current English solution contra- Lip closingmovements for bilabialstops have been reported to be dietsJackson's distinction (based on Harshmanet al.'s two-factorEnglish fasterand of shorterduration for voicelessthan for voicedstops. The vowel solution)between language-independent and language-specific experimentalevidence is conflicting,however, and recordings have mostly vowel articulationprimes. This low-dimensional,potentially cross- beenlimited to lip andjaw movementsin a singledimension. The present linguisticrepresentation could benefit speech recognition, coding, or syn- study examines articulatorykinematics in laCY1 sequences,where the thesisapplications in whichan acousticallycorrelated vowel tongue shape consonantis oneof the set/p,b.t,d,k.g/andthe secondvowel oneof/i,a,u/. parameterizationis required. A magnetometersystem was usedto track vertical,lindhorizontal move- mentsof receiversplaced on the lips andthe jaw, andon four pointson the tongue.Tangential velocity was usedto definemovement onsets and off- sets.Movement amplitude was calculated as the pathof the receiverfrom movementonset to offset.Preliminary results from two subjectssuggest 10:15-10:30 Break the possibilitythat the effectsof consonantvoicing on movementkine- maticsvary for differentarticulators. Tongue body movementstowards consonantalclosure had consistently higher velocity. larger amplitude and longerduration for voicedthan for voicelessvelar stops. Tongue tip andlip andjaw closingmovements showed less robust differences between voiced 10:30 andvoiceless alveoi•r and labial stops. [Work supported byNIH.] 5aSC6. Evaluating a topographicalmapping from speechacoustics to tongue positions. JohnHogden and Michelle Heard (Los Alamos Natl. Lab., MS B256, Los Alamos, NM 87545) 9:45 The continuitymapping algorithm--a procedure for learningto recover the relativepositions of the articulatorsfrom speech signals•is evaluated 5aSC4. Articulatory activity and aerodynamic variation during usinghuman speech data. The advantageof continuitymapping is thatit is voicelessconsonant production. LauraL. Koenig,Anders 1.3fqvist, an unsupervisedalgorithm; that is, it canpotentially be trainedto makea VincentL. Gracco,and Richard S. McGowan (HaskinsLabs., 270 Crown mappingfrom speechacoustics to speecharticulation without articulator St., New Haven, CT 06511) measurements.The procedurestarts by vectorquantizing short windows of The productionof voicelessconsonants is associatedwith changesin a speechsignal so thateach window is represented(encoded) by a single oral air pressurewhich reflectthe time courseand coordinationof the number.Next, multidimensionalscaling is usedto map quantizationcodes requisitelaryngeal and supralaryngealarticulations. The presentexperi- that were temporallyclose in the encodedspeech to nearbypoints in a mentswere conducted in orderto characterizemore precisely the relation- continuitymap. Since speech sounds produced sufficiently close together shipsamong glottal and supraglottalactivities and the resultingaerody- in time musthave been produced by similararticulator configurations, and namic changesin the vocal tract. In the firsl experiment,simultaneous speechsounds produced close together in time are closeto eachother in recordingswere madeof glottalarticulation (obtained via transillumina- the continuitymap, soundsproduced by similar articulatorposilions tion),two-dimensional lip andjaw movements,and air pressurevariation shouldbe mappedto similarpositions in the continuitymap. The data set duringthe productionof voicelesslabial consonants. In the secondexperi- usedfor evaluatingthe continuitymapping algorithm is comprisedof si- ment, two-dimensionalmotion of the jaw and multiple points on the multaneouslycollected articulator and acoustic measurements made using tonguewere obtainedalong with air pressureduring the productionof an electromagneticmidsagittal articulometer on a humansubject. Com- voicelesslingual consonants.Analysis focused on the time-varying pailsonsbetween measured articulator positions and those recovered using changesin thepressure waveform and the accompanyingarticulatory mo- continuitymapping will be presented. tion. The'datasuggest that the overalltime courseof pressurevariation dependslargely on thetiming of the laryngealalevoicing gesture. However, detailsin the pressurewaveforms showed a closecorrespondence to the time courseof supraglottalarticulations. Taken together, results suggest that laryngealand supralaryngealtiming is highlyconstrained, and that 10:45 differentaniculators contribute uniquely to producingpressure variations withinthe vocal tract. [Work supported by N1H.] 5aSC7. Across sessiontemporal stability of the lip-jaw complex in bilabial closure. PeterJ. Alfonso (Dept.of Speechand Hear. Sci., Univ. of Illinoisat Urbana-Champaign,901 SouthSixth St., Champaign,1L 06510) 10:00 Movementsof the tongue, lips, and jaw wer•transdueed byelectro- magneticmidsagittal articulography. A singlesession included 20 repeti- 5aSC5. Three acoustically predictable factors underlying vowel tionsof/pap/,/tat/, and/sas/imbeddedin a carrierphrase at normal,slow, tongueshapes. DavidA. Nix andGeorge .L Paprun (LosAlamos Natl. and fast speechrates. Seven talkers completed three sessions at I week Lab., CIC-3, MS B265, Los Alamos. NM 87545) intervals.Reported here are acrosssession comparisons of temporalorder- To obtaina low-dimensional,speaker-independent parameterization of ing and relativetiming of the movementof the lips andjaw for labial voweltongue shapes, the three-mode factor analysis procedure Ea, RAFAC closureat normalrates. The predominantsequence paRems are thosein [Harshmanet el.,J. Acoust. Soc. Am. 62, 693-707(1977)] was applied to whicheither upper or lowerlip movementoccurs first and jaw movement x-raymicrobeam tongue measurements of ten Englishvowels spoken by occurslast. Across-subject comparisons show that either lip leadsequence two male and two female subjectsin sevendifferent /CVC/ contexts. isequally likely to occur.Within-subject across-session comparisons show PARAF^Creliably extracts three speaker-independent, nonorthogonal fac- no clearpreference for eitherlip leadsequence for somesubjects, and tors.The resulting speaker-independent factor coefficients cluster by vowel reversalsin dominatelip leadsequences for othersubjects. Across-session in three-dimensionalarticulatory space. In two-dimensionalprojections, stabilityof temporalorder is relatedto interarticulatorrelative time: Sub- theyqualitatively reflect the traditional vowel quality chart. A multi-layer jectswho demonstratetight coupling of the upperand lower lips have a perception(neural network) independently corroborates this solution: these higherprobability of producingboth lip-lead sequences, whereas subjects tongueshape coefficients are significantly more predictable from the cor- who demonstratelonger interarticulator relative timing produce consistent 3401 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of Arnedca 3401 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp sequencepatterns across sessions. Temporal measures representing the 11:30 centraltendencies of the complete set of sessionclosure gestures are most 5aSC10.Orofacial and finger force control in normalsubjects. stableacross sessions. [Work supported by NIH DC-00121to Haskins Laboratoriesand University of Illinoisresearch grant.] MicheleGentil (INSERMU 318,CHU, CliniqueNeurologique, BP 217, 38043 GrenobleCedex 9, France), AbdelkaderRezali, Claire Lise Toumier (CliniqueNeurologique, Grenoble, France), Pierre Pollak, 11:00 and Alim L. Benabid (Univ. JosephFourier, 38043 GrenobleCedex 9, 5aSC8.Three-dimensional visualization of humlnjaw motionin France) speech.Thierry Guiard-Martigny (Inst. de la Commun.Par16e, Grenoble The relationshipamong several parameters of the ramp-and-holdforce Cedex9, France)and David J. Ostry (McGill Univ., Montreal,PQ H3A lB1, Canada) contractionand target force level was quantified for the upper lip, lower lip, andtongue on theone hand, and right and left indexon theother hand, With thedevelopment of precise3-D motionmeasurement systems and in 12 normalsubjects (6 malesand6 females).Using visual feedback, powerfulcomputers for 3-D graphicalvisualization, it is possibleto record subjects produced ramp-and-holdcompression lip, tongue, and index and fully reconstructjaw motions.In this paper,a video demonstrationof forcesas rai•idly and accurately as possible to end-pointtarget levels rang- a visualizationsystem for ;:lisplaying 3-D jaw movements in speech will be ing from 0.25 to 2 newtons,these fine force occurringwithin physiologic presented.Kinematic records ofjaw motion and the corresponding speech levelspresumably involved in speechproduction. Given the special arta- signalare recorded using an optoelectronic measuremqnt System. The three tomic and physiologiccharacteristics of the orofacialsystem, the purpose orientationangles and three positions which describe the motion of thejaw of thisstudy wasto comparelip, tongue,and finger force control in order as a rigid skeletalstructure and derived from theempirical measurements. todetermine v•hether the motor control is uniformin bothsystems, that of Thesesix kinematicvariables, which account fully for jaw motionkine- the speechproduction and that of the limb, and within subsystemsof matics,are usedto drive a real-time3-D animationof a skeletaljaw and speechproduction. Consequently, can be pathophysiologyof a movement upperskull. The visualizationsoftware enables the userto view jaw mo- disorderin its stereotypicform be consideredacross limb and speech tionfrom any orientation andto change vigwpoint inihe course ofan systems?It seemslikely that measuresof orofacialforce control provide utterance.Selected portions 9fan.utterance maybe m-played and the speed usefulinsights into the fundamentalmotor control problem of any indi- of the visualdisplay may be varied.The usermay alsodisplay, along with vidual with dysarthria. the audiotrack, individual kinematic degrees of freedomor severaldegrees of freedomin combination.The systemis now beingintegrated into a 3-D audio-visualarticulatoq• speech synthesizer. [Work supportedby NIH Grant DC-00594.] 11:45 11:15 5aSCll.A computationalmodel using formant space planning of 5aSC9.Functional data analysesof lip motion. J.O. Ramsay (Dept. arficulator movements for vowel production. Frank H. Guenther ofPsych., McGill Univ., 1205 Dr. Penfield Ave., Montreal, PQ H3A IB1, (Dept.of Cognitiveand Neural Systems, Boston Univ., I 11 Cummington St., Rm. 244, Boston,MA 02215) and Dave Iohnson (BostonUniv., Canada), K. G. Munhall (QueensUdiversity, Kingston, ON, Canada), Boston,MA) V. L. Gracco (HaskinsLabs., New Haven,CT 06511),and D.J. Ostry (Montreal,PQ H3A IB1, Canada) It isoften hyp'•thesized thatarticulator movements areplanned within The;vocal tract's.motion duringspeech isa complex patterning ofthe a coordinateframe whose variables correspond to key vocaltract constric- movementofmany different articulators according tomany different time tions[e.g., E. Saltzmanand K. G, Munh.all, Ecol. Psych.1, 333-382 functions.Central issuesare the accuratedescription of the shapeof the (1989)].However, recent evidence suggests that speakers may utilize a vocaltract and determining how each articulator contributes to this shape. moreacoustic-like space for planningvowel movements [J. Perkellet al., Techniquesaredescribed that provide useful tools f•>r describing multi- J. Acoust.Soc. Am. 93, 2948-2961 (1993)].Previous work hasverified variatefunctional data such as the measurement of speechmovements. The the capacityof a computationalspeech production model called DIVA to choice of data analysisprocedures has been motivated by the need to explaina widerange of experimentaldata using a constrictionplanning partitionthe articulatormovement in variousways: movement start- and space.The current work extends the model to allowformant space plan- end-effectsseparated from shape effects, effects due t•o different syllables, ningof vowelmovements. The modellearns target regions for F1 andF2 and the splittingof within-sensorvariation from between-sensoroverall foreach vowel during a babblingcycle. A mappingbetween desired for- variation.The techniques of functional data analysis seem admirably suited mantchanges and articulator movements that achieve these changes is also to the.analyses of phenomenasuch as these. Familiar multivariate proce- learned.After babbling, the model successfully reaches all voweltargets duressuch as analysisof varianceand principalcomponents analysis have from any initial vocal tract configuration,even in the presenceof con- their functionalcounterparts, and thesereveal in a way more suitedto the straintssuch as a blockedjaw, and the resultingsynthesized vowels are data the importantsources of variation in lip motion. Finally, it is found easilyrecognizable. Although vowel targetsspecify only formantranges that the analysesof accelerationwere especiallyrevealing in considering with no articulatoryinformation, articulator configurations used by the the characterof possiblecontrol mechanisms. [Work supportedby NIH modelto producevowels are similar to humanconfigurations. [Work sup- GrantDC-00594.] portedby AFOSRF49620-92-1-0499.] 3402 J. Acoust.Soc. Am., Vol. 97, Nol5, Pt.2, May1995 129thMeeting: Acoustical Society of America 3402 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp SATURDAY MORNING, 3 JUNE 1995 GRAND BALLROOM SOUTH, 8:30 TO 11:35 A.M. Session 5aUW Underwater Acoustics:Sea-Surface Scattering Guillermo C. Gaunaurd, Chair Naval SurfaceWarfare Center, Code 684, WhiteOak, SilverSpring, Maryland 20903-5640 Chair's IntroductionS:30 ContributedPapers 8:35 9:05 5aUW1. Shallowwater propagationin the presenceof a rough sea 5aUW3, Sound scatteringby a singleair bubble and by a cloud of surfaceand the associatedbubble clouds. Guy V. Norton (NavalRes. air bubblesnear the seasurface. G.C. Gaunaurdand H. Huang (Naval Lab., Stcnnis Space Center, MS 39529-5004). Jorge C. Novarini SurfaceWarfare Ctr.. White Oak Detachment,Silver Spring, MD (PlanningSystems, Inc., Slidell, LA 70458), and RichardS. Keiffer 20903-5640) (NavalRes. Lab., Stennis Space Center, MS 39529-5004) Soundscattering by an air bubblein a boundlessfluid is an old clas- Propagationmodels in underwateracoustics usually incorporate the sicalproblem [i.e., R. Y. Nishi,Acustica 33, 65-74 0975)]. If the air sea-surfaceroughness asa perturbation,(i.e., a lossmechanism through an bubbleis near,and stronglyinteracting with the surfaceof a liquid half- additionalattenuation factor) based on coherentloss in thespecular direc- space,then the scatteringcross section (SCS) of the bubbleis quitedif- tion.In addition,scattering kernels are generallyderived assuming a ho- ferentfrom its valuefar awayfrmn the boundary.The exactsolution for mogenousmedium underlying the sea surface, an assumptionincompatible this scatteringproblem is given whichis valid for any incidencedirection with a realisticenvironment. Using a numericalmodel [Norton et al., J. of the (plane)sound waves, and for any bubbledepth, obtained by the Acoust.Soc. Am. 95, 3018(A)0994)] thatcombines a high-fidelity para- methodof images.This benchmarksolution is found by meansof the bolicequation propagation model with the conformalmapping technique additiontheorems for the sphericalwave functions. The resultingSCS to handlesurface roughness in a marchingalgorithm developed by Dozier containscontributions from the interface,the bubble,and from its image, [L. B. Dozier,J. Acoust. Soc. Am. 75, 1415-1432(1984)], forward propa- andit is expressiblein termsof couplingcoefficients containing products gationunder a roughsurface can be modeledin a mathematicallyconsis- of Wigher3-j symbols.The formulation is illustratedwith many computed tentway. The techniqueis appliedto theproblem of shallowwater propa- plotsand it is finally extendedto the caseof a round,low-concentration gationin thepresence of an inhomogeneousbubble distribution. The ocean cloudof equalsize bubbles, just beneaththe seasurface. This generaliza- environmentconsists of bubbleplumes in differentstages of development. tionis possibleby replacingthe individual bubble properties by thoseof an The effectof the bubblesare introducedthrough the complexindex of "effectivemedium" describing the bubblecloud just as we foundthem refraction.The model is exercisedfor frequenciesbetween 20 and40 kHz. earlier[i.e., J. Acoust. Soc. Am. 85, 541-554 (1989)]. [Work supported by The combinedeffect that the roughsurface and the inhomogeneousenvi- NSWC'sIR Program.] ronmenthas on amplitudeand phasefluctuations and on transmissionloss is examined.[Work supported by ONR.] 9:20 8:50 5aUW4. Deriving scatteringstrengths from nonstationarytime-series data: A comparison of low-frequency surface-backscattering 5aUW2. The influence of bubble clouds on surface scattering strengths using both impulsive and coherent sources. Roger C. strengths. Michael Nicholas, Peter M. Odgen, and Fred T. Erskine Gauss,Peter M. Ogden (NavalRes. Lab., Washington, DC 20375-5350), (NavalRes. Lab., Code 7142, 4555 OverlookAve. S.W., Washington, DC JohnB. Chester (Naval UnderseaWarfare Ctr., New LondonDetachment, 20375-5350) New London,CT 06320),and JosephM. Fialkowsi (PlanningSystems, Inc., McLean, VA 22102) One of the most comprehensivesets of surfacescattering strength measurementswas made during the CST experimentsbetween August The derivationof scatteringstrengths from acousticfield datainvolves 1988 and May 1993, coveringa frequencyrange from --70 to --1500 Hz. applyingthe activesonar equation to the measuredreverberation response. An extensiveset of environmentalmeasurements (including bubble cloud However,due to the typical nonstationarityobserved in the direct-path measurements)collected on severalof theseexperiments make this a reverberationtime series(e.g., 10 dB/s),the choiceof appropriatecorre- uniquedata set for examiningthe effect of sub-surfacebubble clouds on spondinggrazing anglesbecomes more problematicalas the durationof surfacebackscattering strength. Analysis of thesedata have shownthat the transmittedsignal increases.Direct-path measurementsof low- windspeed, while the most important environmental descriptor, cannot by frequency(200-1000 Hz) acousticsurface scattering were made in the itselfexplain some important differences in thesurface scattering strengths Gulf of Alaskain the Februaryof 1992using interleaved SUS andpulsed measuredfor the differentCST experiments.These differences appear to waveforms(cw, FM). Backscatteringstrengths were derivedfor pulse be linked to the sub-surfacebubble clouds which, in turn, are influenced by lengthsvarying between30 ms and 2.4 s. A comparisonof resultsrevealed the dynamicsof the upper layers of the ocean. Latest results from the that scatteringstrengths have a nontrivialdependence on signal type and continuinganalysis of the surfacescattering and bubble cloud data will be pulselength, and on the signal-processingmethodology used in their deri- presentedwhich illustratethe influenceof the bubble clouds and indicate vation.General implications for derivingscattering strengths from nonsta- how the stabilityof the upperlayers of the oceanplay a role in distributing tionarytime-series data will be discussed.[Work supportedby ONR thosebubble clouds. [Work supportedby ONR.] (NRL).] 3403 J. Acoust.Soc. Am., VoL 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3403 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 9:35 10:35 5aUWS. Low-frequency sea surface scatter and horizontal bistatic 5aUW8. Effect of surface height distributions on underwater angle dependenceutilizing short coherent pulses. John B. Chester acousticbackscattering statistics. Kyle M. Becker (GraduateProgram and Raymond I. Christian (NUWC Div. Newport, New London in Acoust.,Penn State Univ., Appl. Res.Lab., StudentArea, P.O.Box 30, Detachment,New London,CT 06320) StateCollege, PA 16804) A comprehensivelow-frequency (<1000-Hz) low grazing angle A problemof interestto oceanenvironmental acousticians is under- (<30 ø) sea surfaceacoustic scatter experiment was conductedduring standingthe relationshipbetween ocean surface characteristics and acous- Febmary/March1992 in the Gulf of Alaska.During datacollection, wind tic backscatteringstatistics. Recent experimental work has focused on de- speedsranged from 3-17.5 m/s and seastates from 2-6. cw waveforms terminingsurface properties which cause hackscattering strength statistics lessthan 500 ms in lengthat 250, 380, 900, and935 Hz weretransmitted to deviatefrom exponential. Using the nomenclature of Ogilvy(Theory of by threecollinear vertical towed source arrays. Surface scattered energy WaveScattering from RandomRough Surfaces, 1991) severalscattering wasreceived in 17 cosine-spacedbeams by a horizontalsource-ship-towed surfaceshave been fabricated.Surfaces were modeledusing a moving line array.This experimentalgeometry allowed measurement of surface averagetechnique with prescribeddistribution functions and correlation scatteringstrength as a functionof mean grazing angle, frequency,and functionsC(R). Representingsurface elevation, h, asa continuousrandom horizontalbistatic angle. Analysis of thesemeasurements in termsof these process, the moving average process of order N is given as dependenciesis presentedalong with comparisonto currentsurface scat- teringstrength model predictions. hn=•t•=ow•un_ •. Statistical properties ofh aredetermined bythe random uncorrelatedvariables, u,, and the choice of weights,w•. Weightsare determinedby the choiceof C(R) andcorresponding correlation length, X0, or distanceover which C(R) decayshy 1/e. Isotropicand anisotropic 9:50 surfaces have been constructed for both Gaussian and non-Gaussian sur- face heightdistributions. Acoustic backscattering results are presentedfor 5aL7•6. On the correlation of ambient noise levels and other threecases: case I---log-normal height distribution in x and y, equalcor- parameters with backscattering strengths observed during the relationlengths; case H•aussian heightdistribution, correlation length acoustic surface reverberation experiment (ASREX). Nell J. in y equalto ten timesthat of x; caseIlI---Gaussian height distribution in Williams, Hien B. Nguyen, Charles L. Monjo, and Harry A. Deferraft x, log4normaldistribution in y, equalcorrelation lengths. (Appl.Marine Phys., RSMAS, Univ. of Miami, 4600 RickenbackerCswy., Miami, FL 33149) Preliminaryresults from a surfacereverberation experiment performed in the North Atlantic duringthe winter of 1993-94 indicatethat ambient 10:50 noiselevels may prove to be a convenientand accurate indicator of surface backscatteringstrengths. Backscattered energy from coherentsources 5aUW9, Numerical studiesof the small slope approximationfor rangingin frequencyfrom 100 to 800 Hz were observedover a three rough surface scattering using a Pierson-Moskowitz spectrum. monthperiod. Both the backscatteredreturns and ambientnoise were re- ShiraL. Broschat(School of Elec.Eng. and Cornput. Sci., Washington cordedby a 64-elementvertical array while simultaneousmeasurements StateUniv., Pullman,WA 99164-2752)and Eric I. Thorsos (Univ. of were made of a variety of environmentalparameters, including: wind Washington,Seattle, WA 98105) speedand direction,wave spectra,air and sea temperatureand current fields,bubble plumes, etc., by investigatorsfrom SIO, WHOI, and IOS/ The smallslope approximation (SSA), introduced by Voronovichin the BC, Canada.The natureof the data set lendsitself to time seriesanalysis mid-1980s[A. G. Voronovich,Sov. Phys. JETP 62, 65-70 (1985)], has techniques.Multivariate analysis of backscatteringstrengths as a function beenshown to be a very promisingmethod for modelingwave scattering of ambientnoise and variousother environmental parameters will be pre- from roughsurfaces. The theorygives a systematicseries which is mani- sentedand discussed. [Work supported by ONR.] festlyreciprocal at eachorder, reduction to perturbationtheory is intrinsic to the formulation,and reductionto the Kirchoff approximationoccurs underthe appropriateconditions when the firsttwo termsof the seriesare 10:05-10:20 Break retained[E. I. Thorsosand S. L. Broschat,J. Acoust.Soc. Am. 97, 2082- 2093(1995)]. In thispaper numerical results are presented for scattering strengthsfor one-dimensional,pressure release surfaces satisfying a 10:20 Pierson-Moskowitzpower law spectrum.Results are givenfor incident anglesvarying from grazingto normalover the full angularrange of 5aUW7. Backscatteringfrom the ocean surface: Observationsfrom scattering.Comparisons with Monte Carlo integralequation results show the acousticsurface reverberation experiment (ASREX) December thatthe SSAis extremelyaccurate over a largerange of scatteringangles '93-March '94. CharlesL. Monjo,Hien B. Nguyen,Nell J. Williams, includinglow forwardgrazing angles. andHarry A. Deferrari (Appl.Marine Phys., RSMAS, Univ. of Miami, 4600 RickenbackerCswy., Miami, FL 33149) Preliminaryresults from a surfacereverberation experiment that was performedin the NorthAtlantic Ocean during the winterof 1993-94 will 11:05 be presented.Observations of acoustic backscatterfrom the ocean surface weremade from a mooredvertical array at frequenciesranging from 100 5aUW10. A physically motivated model for sea surface to 800 Hz at 12-rain intervals during a 3-month period. Simultaneous backscatteringin the low to moderatefrequency regime. Richard$. measurementswere made by other investigators(from SIO, WTtOI, and Keiffer (NavalRes. Lab., Code7181, StennisSpace Center, MS 39529) IOS-BC, Canada)of a varietyof environmentalparameters, including and JorgeC. Novarini (PlanningSystems, Inc., Slidell,LA 70458) wind speedand direction,wave spectra,air and seatemperature and cur- rent fields, and the presenceand natureof bubbleclouds were observed Basedon the refractiveproperties of the bubbleclouds and the back- with devicesthat detectedanomalies in the nearsurface sound speed and ground(uniform) bubble layer and resonant scattering atthe sea surface, a using high-frequencyside scan sonars.Variation of backscattering simplemodel is presentedto estimatethe backscatteringfrom the ocean strengthswith changesin the environmentwill be presentedand compari- surfacefor frequenciesbelow 1 kHz.This new model yields a dependence sonswith results from other recent observations [P.M. Ogdenand F. T. on thethree fundamental variables, wind speed, grazing angle, and fre- Erskine,J. Acoust.Soc. Am. 95, 746-761 (1994)] will be made.[Work quency,that is in generalagreement with trendsobserved in reverberation- supportedby ONR.] derivedhackscattering data. [Work supported by ONR.] 3404 J. Acoust.Soc. Am., Vol. 97, No.5, Pt.2, May1995 129thMeeting: Acoustical Society of America 3404 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 11:20 stratesa numberof issuesin numericalmodeling of wavescattering: (1) the spreadingof Gaussianbeams (even in homogeneousmedia) has im- 5aUWI1. Modeling sea surface scatteringwith a finite difference plicationsfor (i) definingthe surface footprint or scatteringarea and (•) for method. R.A. Stephen(Woods Hole Oceanogr. Inst., Woods Hole, MA 02543) generatingapproximate Gaussian beams by taperedvertical arrays; (b) the treatmentof a rough,free, fluid surfacein a Cartesiangrid scheme;(c) A numericalscattering chamber based on the finitedifference solution solvingcontinuous wave (cw) problemsin thetime domain; (d) diffraction of thetwo-way elastic wave equation is appliedto thesea surface scatter- of wavesfrom roughness elements with scalelengths on the orderof a ingproblem. For a referencemodel, the method gives excellent agreement wavelength;(e) multiplescattering effects between roughness elements; in amplitudeand phase with the solution obtained by an integralequation and(t') omni-directional scattering including low angle backscatter. [Work method[Eric Thorsos, personal communications]. This problem demon- supportedby Office of Naval Research.] SATURDAY AFTERNOON, 3 JUNE 1995 MEETING ROOM 3, 1:00 TO 4:05 P.M. Session5pBV Bioresponseto Vibration and to Ultrasoundand PhysicalAcoustics: Biomolecular Acoustics Armen Sarvazyan,Chair Departmentof Chemistry,Rutgers University, P.O. Box939, Piscataway,New Jersey 08855 Chair's Introduction--l:00 Invited Papers 1:05 5pBV1.UItrasonic studies of phasetransitions in lipidmembranes and protein molecules. DmitriP. Kharakoz (lnst. of Theoret. andExp. Biophys.,Russian Acad. Sci,, 142292Pushchino, Moscow, Russia) Thispaper reviews phase transitions in the lipid membranes and protein molecules studied by means of ultrasonic(sound velocity andabsorption) and related methods (calorimetric, volumetric, and others). Peculiarities of phase transitions in small-dimension systemsin anaqueous environment (a finite width of thetransition zone, probability of criticalnuclei formation, hysteresis, hydration changes,etc.) are discussed. A comparison of ultrasonic and calorimetric methods showing their complementarity in the studies of kineticsof phasetransitions is presented. Ultrasonic data on the melting of lipidvesicles in aqueousdispersions are reviewed. Recent achievementsin the ultrasonic study of thekinetic mechanism of creation and growth of gelnuclei within the parent liquid-crystalline phaseare reported. Ultrasonic studies of theprotein/lipid interactions are reviewed and perspectives are outlined. Native to molten globulestate transition in globularproteins is considered(volume and compressibility changes, acoustic relaxation, protein interior hydration).The differencesin thebehavior of the phasetransitions in membranesand in proteinmolecules are discussed.New questionsfor furtherultrasonic studies of the phasetransitions are formulated. 1:35 5pBV2.Molecular acoustics in thermodynamiccharacterization of proteins.Tigran V. Chalikian(Dept. of Chemistry,Rutgers Univ., Piscataway,NJ 08855) Processessuch as conformational phase transitions, ligand binding events, and enzymatic catalysis alter the structure of proteins aswell as the nature of theirsolvent accessible surface. Consequently, these processes result in correspondingchanges in thesound velocityof theprotein solution. As is shownby the example of twotypical globular proteins, cytochrome c and a-chymotrypsinogen A, thetransition from the native state to themolten globule state is accompaniedby an increasein soundvelocity, while the native state-unfoldedstate transition is accompaniedbya decreasein soundvelocity. The interpretation of the macroscopic sound velocity datafor thedifferent phase states of proteinsin termsof microscopicstructural and hydrational differences is a verysophisticated problem.One of the waysof attemptingto solvethe problem of distinguishingbetween the contributions of proteinstructure and hydrationto thesound velocity is to searchfor correlationsbetween the structural crystallographic data of a largenumber of globular proteinsand their ultrasonicvelocimetric characteristics. 2:05 5pBV3. Macromolecularabsorption: The roles of molecularsize, structure, solvation, and soluteinteractions. FrederickW. Kremkau (Ctr.for Med. Ultrasound,Bowman Gray School of Medicine,Wake Forest Univ., Winston-Salem, NC 27157-1039) Altenualion of ultrasound in tissuesis due primarily to macromolecular absorption. Biomacromolecules•aave t•iglaer absorpttons thanthe constituent molecules of whichthey are made [F. W. Kremkauand W. Cowgill,J. Acoust.Soc. Am. 76, 1330-1335(1984)]. Absorptiondependencies on structure[F. W Kremkauand R. W Cowgill,J. Acoust.Soc. Am. 77, 1217-1221(1985)] and solration [E W. Kremkau,J. Acoust.Soc. Am. 83, 2410-2415(1988)] are probably interrelated. Underlying absorption processes are enhanced or newprocesses are added under conditions of highconcentration, aggregation, or crosslinking [F. W. Kremkauet al., J.Acoust. Soc. Am. 53, 1448-1451(1973)]. 3405 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3405I Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 2:35-2:50 Break 2:50 5pBV4.Major accomplishments in development of acoustic instrumentation for biomolecular studies. Armen P. Sarvazyan •I (Dept.of Chem.,Rutgers Univ., New Brunswick,NJ 08903) A greatpotential of acousticsin thethermodynamic characterization of biomolecularsystems, studies of conformationaltransitions and hydrationof proteinsand nucleicacids and drug-biopolimerinteractions has beenrevealed in the last decademainly due to advancesin the instrumentationfor ultrasonicmeasurements in small volumesof liquids.The methodsand devicesreviewed in this talk arebased upon the fixed path interferometer method, also known as a "resonatormethod." It is theonly methodwhich can provide measurementsof ultrasoundvelocity and attenuation in the samplevolume of the orderof 10-100 microliterswith sufficientprecision. The requirementof small samplevolume is a major preconditionfor applicabilityof the methodto the most of the problemsin biomolecularstudies. Different types of resonatorswill be describedin detail includinga new type of micro-volumecylindrical standingwave resonatorswith a chambervolume of about3 microliters.The electroniccircuits for high precisionmeasurement using acousticalresonators are usuallybased on the phase-lockedloop whichprovides the oscillationin the systemat the chosenresonance. Fieldsof applicationsand prospects of future development of instrumentation willbe reviewed. a/Permanent address: Inst. of Theoret. and Exp. Biophys.,Russian Aced. of Sci. ContributedPapers 3:20 E.coli bacteriathat have been geneticallyengineered to emit visible light whensubjected to physicalor chemicalstress. Genetic cloning techniques 5pBV5. Passive acoustic fetal heart rate monitoring with a parallel allow the placementof the lux gene, derived from luminescentmarine redundance approach. Stephen A. Zahorian, Zongyao Zhou, and microorganisms,at specificlocations in bacterialDNA. Each placement CharlesBrewton (Dept.of Elec.Eng., Old DominionUniv., Norfolk, VA locationyields light productionin proportionto the repair mechanism 23529) employedby thebacteria in responseto specifickinds of stress(oxidative Acousticmethods for monitoringfetal heart rate are potentiallyadvan- damage,DNA damage,membrane damage, protein damage, thermal dam- tageousover ultrasoundmethods, since, eventually,long-term low-cost age,etc.). A 20-MHz passiveacoustic detector [abstract, Huertas et al., J. monitoringwould be possiblefor high risk mothers,with no concernfor Acoust.Soc. Am. 95, 2856 (1994)]was used to quantifycavitational ac- fetal damagedue to the monitoringdevice. However, sensordesign and tivity when bacteriawere exposedto 1-MHz pulsedultrasound. By com- signal processingrequirements are very demandingin this low signal-to- paringa measureof cavitationalactivity with light outputfrom exposed noise ratio environment.The presentapproach is patternedafter that by bacteriathat were presensitizedto differentkinds of damage,cavitational Zuckewaret el. [IEEE Trans.Biomed. Eng. 40-9, 963-969 (1993)]using effects on both bacteria and mammalian cells can be better understood. a third-generationsensor belt, and enhancedsignal processingstrategies. 3:50 In the new method,each of sevendifferential sensor signals is scanned continuouslyand processedin parallelwith a PC-hostedDSP system.The 5pBV7. Intestinal hemorrhage produced by pulsed ultrasound or processingof eachchannel includes FIR bandpassfiltering, Teaget energy lithotripter fields. Diane Dalecki, Sally Z. Child, Carol H. Raeman, calculations,autocorrelation, and "intelligent" peak picking. "Candi- andEdwin L. Carstensen(Dept. of Elec.Eng. and the Rochester Ctr. for dates"for fetal heartrate are computedevery 0.5 s and evaluatedwith a Biomed.Ultrasound, Univ. of Rochester,Rochester, NY 14627) figure of merit which incorporatesboth measuresof peak quality and continuityconstraints. Clinical testingindicates that the new methodof The thresholdfor intestinalhemorrhage in micewas determined using signalprocessing is able to reliably track fetal heartrate for mostfetuses a piezoelectriclithotripter. Mice were exposedto 200 lithotripterpulses with a gestationage of at least30 weeks.The multiple-channelapproach witha PRF of • 1 Hz. Theamplitude of exposurewas determined by either resultsin a significantimprovement over a single-channelmethod. varyingthe positionof the animalrelative to the focusor by varyingthe voltageused to chargethe lithotripter. Threshold for intestinalhemorrhage occurredat a peak acousticpressure of 1-2 MPa. At threshold,the lithot- 3:35 ripter waveform was nearly sinusoidal.Thresholds for intestinalhemor- 5pBV6. Effects of acoustic cavitation on luminescent bacteria. E. rhagewere also determined for exposureto pulsedultrasound at frequen- Carr Everbach,lnder R. S. Makin, and Amy ChengVollmer (Dept. of ciesof 0.7, I. 1, 2.4, and3.6 MHz. Intestineswere exposed at 3-4 sitesfor Eng. and Biol., SwarthmoreCollege, Swarthmore, PA 19081-1397) 5 rain per site usingfocused sources operating with a 10-/aspulse length and 100 Hz PRE The threshold at 1.1 MHz was --1.5 MPa and thresholds The interactionof intenseultrasound with bacteriahas implications for increasedwith increasingfrequency. Temperature rises of 1 -2 øC were improvingfundamental understanding in biologyand bioacoustics, as well measuredin the intestineduring exposure at the highestexposure condi- as providingpossible applications in water purificationand medicine.An tions.Both the frequencydependence of intestinalhemorrhage and the investigationwill be presentedof the effects of acousticcavitation on limited heatingare consistentwith a cavitationmechanism of action. 3406 d. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3406 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp SATURDAY AFTERNOON,3 JUNE 1995 MEETING ROOM 2, 12:55TO 3:45 P.M. Session5pMU MusicalAcoustics and Noise:Acoustic Ecology Fred Lipsett,Chair 37 Oriole Drive, Gloucester,Ontario K1J 7E8, Canada Chair's Introduction--12:55 Invited Papers 1:00 5pMUI. Soundin context:Acoustic communication and soundscaperesearch at SimonFraser University. BarryTruax (Schoolof Commun.& Schoolfor theContemporary Arts, Simon Fraser Univ., Burnaby, BC VSA1S6, Canada) Researchactivities at SimonFraser University over the past 25 yearsthat bridge environmental acoustics and music are summa- rized,including soui•dscapd studies, acoustic communication, soundscape composition, andthe granulation ofsampled sound. Gaps in traditionaldisciplinary approaches in dealingwith environmentalsound are identified,and an acousticcommunicational model is proposedas an interdisciplinaryalternative. Sound examples drawn from the author's compositions, and the work of R. Murray Schafer,Hildegard Westerkamp and the World Soundscape Project will be included. 1:30 5pMU2.Community noise: The mainstreamapproach. Kenneth J. Plotkin(Wyle Labs., 2001 Jefferson Davis Hgwy., Ste. 701, Arlington, VA 22202) Communitynoise analysis and control has been a concernfor centuries.The introductionof jet commercialaircraft in the 1950s escalatedit to a widespreadpractice with widelyaccepted quantitative rules. The ruleshave their technical basis in scientificstudies rangingfrom laboratory psychoacoustic experiments through social attitudinal surveys. Implementation is in the form of landuse planningand noise control regulations. A review is presentedof thecurrent practice, its successes,and its limitations. 2:00 5pMU3. Acoustichygiene: The importanceof protectingears, lungs,and other organsfrom acousticinsult. MichaelA. Zagorski (Dept.of Psych.,Memorial Univ. of Newfoundland,St. John's,NF, Canada) Whilethe importance of controllingnoise is widelyaccepted, the major concern has been with annoyance. The publicis not generallyaware of thepotential severity of evena fewnoise exposures. Most people do not realize the extent to whichthey use acousticcues in dailylife, northe extent of debilitationassociated with recruitment or lossof binauralabilities. Similarly, most do not realizethat a flyoverproducing short-term noise measurement of a littleover 130 dBA can have the same effect on the lung as 2 lbs. of TNT explodinga meter or twofrom the body. h is arguedhere that to promoteacoustic hygiene the public must be madeaware thathearing loss is a complexand serious handicap that is notgenerally corrected with hearing aids. To do thisemphasis must be placedon theimportance of acousticcues in everydayactivities even without speech, the handicap produced by notbeing able to localize,the difficulty of hearingin crowds,and the annoyances of hearing aids. A numberof methodsfor illustratingthe effects of hearingloss and the value of normalhearing will bepresented and demonstrated. [Work partially supported by theNational Research Councilof Canada.] 2:30 5pMU4. From a "soundobservatory" to a "soundcity" masterplan. AndresBosshard (Wildbachstr. 62, CH 8008 ZiJrich, Switzerland) "Soundsculptures," "sound installations," and "telematic media network links" can be considered asobservatories assoon as they look for resonances,reverberations, and otherspatial qualities of the actualsite and if they are composedto look for possible interactionwith the ongoing stream of soundsof thereal environment. Time structures of humanperception and behavior help to find a basisfor "soundperspectives" and "territorialsound fields" and "tidal soundspheres," which can be stimulated,simulated, and modifiedbyadvanced electroacoustic networks. The "l•angturm" inSt. P•lten, Austria and the "Adi Srvya" sound gallery in New Delhi, India are two house-sizedmusical instruments under construction; both will be openedin fall 1996. Field researchof the indigenous"Sanfal" populationin WestBengal, India, showsvery sophisticatedand complex "natural" soundarchitectures for entire towns.The acoustictuning of the "Santal" villagesis a basicmodel for an acousticand electronicstudy to preparea "soundcity" masterplan. 3407 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3407 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp ContributedPapers 3:00 m modelparameters, such as latin hypercubeMonte Carlo samplingand by adjointmethods, as well as decision-makingapproaches including sta- 5pMUS. Understanding individual differences in response to tisticalhypothesis testing will be discussedfor comparingalternatives to environmental noise: An essential step in determining health risk. control unwanted sounds. SusanL. Staples (58 Spong]aRd., StoneRidge, NY 124841 Evidenceis reviewedindicating that psychologicaland socialfactors renderpeople more or lesssusceptible to stress-relatedhealth effects from 3:30 nmse.Factors such as appraised meaning, personality traits, and.p•rceived controlare consideredin termsof their relationshipto physiologicalvan- 5pMU7. Characterization of the sound quality of vacuum cleaners. ables and in terms of the mechanismsunderlying adverseeffects. The Guyot Fr6d6rique,Piron Christine.Castellengo Michele. and Fabre limitationsof epidemiologicaland dose-response methods for determining Benoit (Lab. d'Acoust. Musicale. Univ. Pierre et Marie Curie. Tour 66 andunderstanding health effects are discussed.Modifications in theseap- Case 161, 4 placeIussieu, 75252 ParisCodex 05, Francel proachesare suggestedto clarify the role of interveningpsychological factors,to understandthe physiologicalmechanisms •mplica,ted, and to The intensitylevel is not the only parameterresponsible for noise delineatepublic health risks. ,-• disturbance.The basis of theperceived world is thecategorization process whichpermits recognition and qualitative appreciation. This study is based on Rosch'scategorization concept. [E. Rosch,Cognitive Psychol. 7, 3:15 • 573.605(1975)]. In orderto estimatethe pleasantness features of a setof 5pMU6. Acoustical ecological risk. Timothy S. Marguiles I Johns 23 vacuumcleaner noises and to characterizethe prototypeof "thepleas- HopkinsUniv., Baltimore,MD 212181 ant aspiratornoise," a free categorizationmethod was adopted. The sub- jects are askedto group,in a free numberof categories,the noisesaccord- Risk-basedprioritization and decisionmaking has been implemented ing to the corafortsensation they evoke.By analyzingthe resultsthe role by the U.S. EPA in severalareas to assurequality and consistencyof risk playedby the typicalityand the gradationphenomenon in the structures and environmentalassessment and to identify areasto reduceuncertainty. relativeto thesenoises quality can be estimated.Finally, the organization This talk will reviewthe elementsof risk assessmentand risk management of thesecategories •s analyzedby estimatingon one hand the relative and will comparethe paradigmsfor consideringprimarily tonizing radia- importanceof parameterscoming exclusively from noisesphysical con- tion and mechanicalradiation to assessexisting and projectedrisks to tent,and on anotherhand. the significanceg•ven to the stimuliby each humanhealth and the environment.Treatment of uncertaintypropagation subject. SATURDAY AFTERNOON, 3 JUNE 1995 RENAISSANCE WEST A, 12:30 TO 2:30 P.M. Session5pPAa PhysicalAcoustics: Photoacoustics W. Patrick Arnott, Chair AtmosphericandEnergy and Environmental Engineering Centers, Desert Research Institute, UniverSity ofNevada, P.O. Box 60220, Reno, Nevada 89506 Invited Papers 12:30 5pPAal. Resonantphotoacoustic measurements of opticalabsorption in solids. Wei-liLin (Dept.of Phys.,Penn State Univ., UniversityPark, PA 16802) For glassesand crystals the opticalabsorption near the infraredis muchlower than that in the visible.While the previous noncontactresonant photoacoustic (PA) measurement is several orders of magnitudemore sensitive than that of conventionalPA in the visiblefor a piezoelectricsample, it wasfurther developed to applyto nonpiezoelectricmaterials in thenear infrared. The noncontact interdigitalcapacitor transducers were replaced by lithium niobatedisks and PVDF films. By supportingthe sample between trans- ducersonly at its comers, the quality factor has been improved and is comparable tothat of a noncontactsystem, while the separate supportsand the precise positioning of thesample are avoided. An opticalabsorption coefficient on the order of 10-7 cm ] at 1.06/.an hasbeen measured with a 20 signal-to-noiseratio.Recent results on single crystals of quartzand calcium fluoride, using different piezoelectrictransducers, will bediscussed. [Work supported byNSF Grant No. DMR-9000549 and by the Office of NavalResearch.] 12:55 5pPAa2.Resonant photoacoustic measurements ofoptical absorption ingases.' Wayne M.Wright (Dept. ofPhys., Kalamazoo College,Kalamazoo, MI 49006) Theuse of the photoacoustic (oroptoacoustic) effect in spectroscopygives a valuabletool for examining weak optical absorption featuresof gases.It is inherently a more sensitive detector oflight absorption than other techniques, which attempt tomeasure a small attenuationof an intensebeam. Instead, absorption by thegas of periodicallyinterrupted optical energy, from either a tunableor fixed-wavelengthlaser, results in theproduction of soundat thesame frequency. Device optimization has followed a numberof 3408 J.Acoust. Søc; Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society ofAmerica 3408 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp differentpaths. The particular approach emphasized here uses a cylindricalgas cell, driven at its 1stazimuthal acoustic resonance, to increasesignal amplitude. Experimental concerns include enhancement of the signal relative to acoustic and electronic noise. Examples arepresented of whatcan be learned through application of thistechnique. These include results for theabsorption of visiblelight by nitrogendioxide and aerosol particles, as well as from a studyof theprofiles of oxygenabsorption lines in theinfrared region. 1:20 5pPAa3. Transient grating studiesof nonlinear photoacousticeffects in particulate solutions. G.J. Diebol, H. X. Chen, Y. N. Cao, and M. B. Zimmt (Dept. of Chem.,Brown Univ., Providence,RI 02912) Experimentswhere transient grating signals are recorded from irradiationor particulatematter are reported. A relativelylow power, picosecondlaser produces transient grating signals in reversemiceliar solutions that have a uniquetime dependence,and whichcan be explainedby heatdiffusion from the interiorof the micelieto a surroundingorganic solvent. A 16-ns-long,high-power pulse from a Q-switchedND:YAG laserirradiating a gold sol producesa diffractedlight signalthat is explainablein termsof a thermally generatedphotoacoustic effect. Particulate carbon, on theother hand, gives transient grating signals that appear to possessan overtone of the usualthermally generated fundamental frequency. The effectis nonlinearin its dependenceon the laserintensity, and is dependenton thetime of irradiationof thesolution. A secondcharacteristic of the effect is thata pronouncednoise is generatedby the solutionon firingthe laser.It is believedthat the effectscan be attributedto endothermicchemical reactions at the surfaceof the carbon that act to unbalancethe thermaland acousticmodes producing an acousticdensity that oscillatesabout the ambient.Since the diffractedlight signal is proportionalto thesquare of theacoustic density, what appears to theeye as an overtoneis seenin therecorded signal. ContributedPapers 1:45 behaviorof the opticalpath underthis flexureis studiedusing the beam propagationmethod. Predictions of the opticalsensitivity (depth of modu- 5pPAa4. Forward and backward projection of transient acoustic lationversus membrane displacement), and optical insertion loss are thus field functions obtained from schlieren and fiber-optic obtained.Third the signal-to-noiseperformance of the deviceis evaluated measurements. Jie Sun, Peter R. Stepanishen(Dept. of Ocean Eng., by representingall noisesources as equivalentacoustic noise fields at the Univ. of Rhode Island. Kingston, RI 02881), Gregory Clement, microphoneinput. Applications of this methodologyto opticalmicrophone RuimingLiu, andStephen V. Letchef (Univ.of RhodeIsland, Kingston, designsunder consideration are described. RI 02881) A combinationof a schlierensystem and a polarimetricfiber-optic 2:15 detectionsystem is usedto obtainline integralsof transientacoustic fields a distancez in frontof a planarsource. The x,y dependenceis obtained 5pPAa6. Signal-to-noise ratio of thermoacoustic enhanced from a tomographicreconstruction algorithm. The signalis thenforward photoacousticspectrometers. W. Patrick Arnott, Hans Moosmiiller, projectedaway from the sourceor back-projectedtoward the sourceusing RobertE. Abbott,and Michael Ossofsky (Atmosphericand Energy& wave vector/timedomain and frequencymethods. Numerical results will EnvironmentalEng. Ctrs., DesertRes. Inst., Univ. of Nevada,P.O. Box be presentedto illustratethe projectionmethods for a numberof different 60220, Reno, NV 89506) transientsignals from planar sourceswith separableand nonseparable The quality factor, Q, of plane or radial wave resonatorscan be in- space/timevelocity distributions. Experimental results for selectedsource creasedand controlledusing thermoacoustics. When sucha resonatoris distributionsfrom pulsed ultrasonic transducers will thenbe presentedand discussed. Usedin photoacoustics,a laser beam passes through it andsound is pro- ducedwhen light absorptionoccurs. Sound amplitude is proportionalto the coefficientfor light absorption,to the resonatorQ, and to the laserbeam 2:00 power.Traditionally, resonator dimensions have determinedboth the cou- pling strengthof the laserbeam to a particularmode and the qualityfactor. 5pPAaS. Modeling of optical microphone performance. Nykolai Bilaniukand Andr6Delfige (Inst. for MicrostructuralSci., Natl. Res. High couplingstrength is desirable,but impliesuse of a narrowresonator Councilof Canada,Ottawa ON K1A 0R6, Canada) wheremost of the interioris filled with laser.On the otherhand, high Q traditionallyimplied need for a Wideresonator. Thermoacoustics canbe A numberof modulationprinciples and an even largervariety of spe- usedto increasethe Q of the narrowresonator to optimizethe acoustic cificimpleme•ntations maybe considered for all-opticalmicrophones. The signal. Our theory and measurementsshow that the thermoacoustically proceduresfor designingoptical microphones described in this paperin- enhancedphotoacoustic spectrometer can be viewed as an analognarrow- cludethree principal steps. First the mechanicalresponse of a membraneto bandamplifier for soundwhere the resonancefrequency is f0, the band- an acousticfield is modeledby an analyticaltechnique [A. Hu et al., 1. width is fo/Q, the gain is Q, and the signal-to-noiseratio for discrimina- Acoust.Soc. Am. 91, 3049-3056 (1992)],and is usedto obtainthe mag- tion againstGaussian acoustic noise in the resonatoris Q•/2. [Work nitudeof the membranedeformation and its frequencyresponse. Next the supportedby the EPA,ONR.] 3409 d. Acoust. Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp SATURDAY AFTERNOON, 3 ,JUNE 1995 RENAISSANCE WEST A, 2:45 TO 4:45 P.M. Session5pPAb PhysicalAcoustics: Thermoacoustics, Bubbles, and Droplets Paul E. Barbone, Chair Departmentof Aerospaceand MechanicalEngineering, Boston University, Boston, Massachusetts 02215 ContributedPapers 2:45 thewave equation. An analysisis presentedincluding this term to study twoimportant questions: What is the optimal slope, and even more basic, 5pPAbl. Numerical study of a simplified model of nonlinear whichside (hot or cold) should have the greater plate separation? [This processesin thermoacousticengines. A. Prosperettiand M. Watanabe workwas supported by the Officeof Naval Research.] (Dept.of Mech.Eng., Johns Hopkins Univ., Baltimore, MD 21218) 3:30 A simplified one-dimensionalmodel of thermoacousticdevices, ob- tained by integratingthe governingequations over the tube crosssection, 5pPAb4.The effectof phaseof the acousticwave on the efficiencyof was describedearlier. Here the resultsof a numericalexploration of the thermoacousticrefrigerators. JamesBrewster and Richard Respet modelas appliedto a primemover are described.The effectsof tempera- (Dept. of Phys and Astron., Natl Ctr. for Phys. Acoust..Univ. of ture distribution,wall drag, heat transfer,and cross-sectionalarea varia- Mississippi,University, MS 38677) tionsare exploredand compared with availableexperimental results. Some initialresults for the heat pump configuration will alsobe presented. [Work An analyticapproach to the studyof thermoacousticsand application supportedby the Office of Naval Research.] of thistechnique tothe optimization of a refrigeratordriven by an arbitrary acousticwave will bepresented. It will beshown that although a standing wavedriven cooler has close to optimumefficiency, the efficiency can be •mprovedby theaddition of a travelingcomponent to thewave field flow- 3:00 mg m the directionof negativetemperature gradient. The value of the 5pPAb2.Visualization of oscillatingtemperature and flow fields in acousticimpedance in the gasbordering the cold end of the stackis fixed the stack region of a thermoacousticrefrigerator model. C. Herman, to anarbitrary value. Application of thecontinuity of pressureand velocity M. Wetzel,and M. Volejnik (Dept.of Mech.Eng., Johns Hopkins Univ., •scombined with the wave equation to yieldthe value of thepressure wave function and its first two derivatives at the cold end of the stack. Knowl- Baltimore, MD 21218-2686) edgeof theseallows the direct calculation of theefficiency of refrigeration In orderto studythe oscillatingtemperature and flow fieldsin the stack andthe second derivative of thetemperature distribution. [Work supported region,a modelof a thermoacousticrefrigerator is built. The modelallows m part by Office of Naval Reseamh.] theapplication of visualizationtechniques such as holographic interferom- etry, thermochromaticliquid crystals,and smokeinjection. In the first 3:45 experiments,the correctoperation of the thermoacousticrefrigerator is 5pPAbS.Numerical simulation of gas cavity responseto shock verified.Using the Kundt's dust tube method, the propagation of longitu- waves. ZhongDing and S. M. Gracewski(Dept. of Mech.Eng., Univ. of dinal plane-wavefronts is analyzed.Furthermore, the distortiondue to the Rochester.Rochester. NY 14627) presenceof higherharmonics in the resonancetube is kept small.This is verifiedby applyingthe Fouriertransform to a pressuresignal at several An understandingof cavitation phen, omena including the response of a positionswithin the resonance tube. The focusof currentinvestigations is gascavity in liquidto a time-dependentpressure wave ts importantin a to apply the abovevisualization techniques in the stackregion and its largerange of situations.In thepaper, the response of a gascavity in water neighborhood.These measurementsprovide informationwhich can be to shockwaves is analyzedusing the arbitrary Lagrangian-Eulerian tech- usedto determinerequirements for the designof heatexchangers. An toque.An axisymmetricmodel is usedin thenumerical simulation of a gas improveddesign of the heatexchangers and a betterunderstanding of heat cavityresponse to bothweak shocks (P/Pc •<300. with p0=0.1 MPa) and transferprocesses and flow phenomenaare key issuesto improvethe strongshocks (plpo ranges from 5000 to 20 000).An artificialviscosity to efficiencyof thermoacousticrefrigerators. [Work supported by theOffice capturethe shockwas developed. A simple,stable. and adaptive mesh of NavalResearch; Martin Wetzel is alsosupported by a scholarshipfrom generationtechnique was designed to generatefiner meshes at higher pres- suregradients. The shockpropagation. rarefaction, and transmission were analyzedover the entire computational domain. When impacted by a weak shock,a gascavity will collapsealmost spherically creating a largepres- surewithin the gas and the surrounding liquid due to therapid compression 3:15 of thegas. When impacted by a strongshock, a gascavity will collapse 5pPAb3. Plane- and radial wave thermoacousticengines with witha jet penetratingthe opposite side of theinterface with a speedas high as 2000 m/s. variable plate separation. JayA. Lightfoot,Richard Raspet, Henry E. Bass (Dept.of Phys.and Astron., Univ. of Mississippi,University, MS 4:00 38677),and W. PatrickAmott (Univ.of Nevada,Reno, NV 89506) 5pPAb6.A new kind of multiple-dropletlevitator. YnrenTian and Rott developedthe theoryof thermallydriven acousticoscillations in tubeswith variable crosssection. Bennett, in her dissertation,considered RobertE. Apfel (Ctr.for Ultrason(csand Son(cs, Yale Univ., New Haven, CT 06520-8286) plane-wavethermoacoustic refrigerators with variable plate separation and foundthem to havehigher COP's than those with parallelplates. This Manydifferent kinds of levitatorsare used to studyliquid drops. In principlehas application to thework in radialwave thermoacoustics, since mostof them,only a singledrop can be leviteted.Under some circum- variableplate separation isa naturalproduct of radialvertical-plate engines stances,however, it is desired to levitate multiple drops simultaneously. An withconstant plate thickness. Bennett appears to haveoverlooked a termin acousticallevitator has been modified for thepurpose of multiple-droplet 3410 J. Acoust.Sec. Am., Vol. 97, No.5, Pt.2, May1995 129thMeeting: Acoustical Society of America 3410 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp levitation.During the experiments, a liquid is pouredon the surface of the withthe related nonlinear wave equation. The high-and low-frequency acoustictransducer and is ultrasonicallyatomizer. By applyinga static limitsare then analyzed, and traveling wave solutions are sought in each electricfield on thesurface of the liquid,the atomized drops are electri- case.Comparison is made with existingresults for nonlinearwaves in cally charged,After the dropsare dispersedinto the levitutor.they can be bubblymedia. containedtogether and leviratedby acousticradiation force. Coalescence amongthe dropsis preventedby the forcesof electricrepulsion. The 4:•0 separationdistance between the drops. Ibe choplet size. and the numberof levitateddrops can be controlledby theintensity of theacoustic and dec- 5pPAb8. Feasibility of low-frequency single-bubble sonolumin- lric fields.Preliminary experimental results will be reported,including the escence. Robert E. Apfel, Tan Shi, Joseph Jankovsky,Jeffrey observationof masstransfer among the leviteled drops. [Work supported Ketterling,and Xiaohui Chen (Dept. of Mech. Eng., Yale Univ., New by NASAthrough JPL. contract 958722.] Haven, CT 06520-8286) The potentialto performsingle-bubble sonolumineseence (SBSL) at 4:15 low frequenciesis motivatedby the payoff of greatlyenhanced energy concentrationduring collapse. Yet it is alsoknown that bubbles undergoing 5pPAb7. Nonlinear acousticsof bubbly liquids: Traveling wavesin a suchcatastrophic collapse tend to be unstable.Experimental apparatus has quadratic approximation. Daniel Goldman,All Nadim, and Paul E. Barbone (Dept. of Aerosp. and Mech. Eng., Boston Univ., 110 been designedand computersimulations have been performedto test the CummingtonSt., Boston,MA 02215) feasibilityof low-frequency,single-bubble sonoluminescence. The experi- mentalapparatus consists of a cylindricalcell thatis drivenby an alumi- An importantaspect of underwateracoustics is the effectof trapped num, half-wavelengthresonator with fundamentalresonance of lessthan cloudsof air bubbles.Recently, an approachto wavepropagation in dilute 15 kHz. The cell is designedto be pressurizedup to 5 atmospheresto allow bubblyliquids was described in whichthe Rayleigh-Plessetequation is levitationwithout significant spurious cavitation in the liquid.To comple- usedto derive a nonlinearequation of statefor the gas bubble-liquid mentthis experimental work, our computer simulations of thisphenomena mixture[Nadim et el., Bull.Am. Phys.Soc. 39, 1976(1994)]. In this arecontinuing IT. Shiand R. Apfel,]. Acoust.Soc. Am. 96, 3253(1994)] formulation,the pressure in themixture depends in a highlynonlinear way in order to follow the shapedistortion of collapsingbubbles for varying on the localdensity and its firstand secondtime derivatives.Linearization parameters,including acoustic frequency. The basiccharacteristics of our leadsto the standardacoustic equation for bubblyliquids. Here the qua- low-frequencyresonator and the resultsof experimentalwork and com- draticapproximation to the nonlinearequation of stateis examined,along putersimulations will be reported. SATURDAY AFTERNOON, 3 JUNE 1995 AUDITORIUM, 1:15 TO 5:45 P.M. Sexton 5pPP Psychologicaland PhysiologicalAcoustics: Binaural and Spatial Hearing; Cochlearand Auditory Nerve Function Kim S. Abouchacra,Chair U.S.Army Research Laboratory, AMSRL-SD-HR, Building 520, Room39, AberdeenProving Ground, Maryland 21005-5425 ContributedPapers 1:15 1:30 5pPPI. A dynamic, psychophysical model of adaptation in 5pPP2. Model simulationsof masked thresholdsfor tones in dichotic localizationexperiments. BarbaraShinn-Cunningham (Res. Lab. of noise maskers. !nga Holube,H. StevenColburn (Dept. of Biotaed. Electron.,MIT, 77 MassachusettsAve., Cambridge,MA 02139) Eng.,Boston Univ., 44 CummingtonSt., Boston,MA 02215), Steven van de Par, and Armin Kohlrauseh (Inst. for PerceptionRes. (IPO), Eindhoven,The Netherlands} Previouspsychophysical models have describedhow resolutionde- pendsupon the rangeof physicalstimuli employed in a givenexperiment; however,these models generally assume that subject performance is stable The studyof maskedthresholds in dichoticnoise maskers is important over time.The currentwork extendsthe context-codingmodel of Duriach for understandingthe processingin binauralhearing. To simulatethese andBraida [I. Acoust.Soc. Am. 46, 372-383 (1969);Braida and Duriaeh, thresholdsa psychoacoustically motivated perception model was used IT. Dau et al. (1995). "A quantitativemodel of the "effective"signal pro- J. Acoust.Soc. Am. 51,483-502 (1970)]to accountfor changesin subject cessingin theauditory system: I. Modelstructure," submitted to L Acoust. performancethat occurwhen feedback is usedto retrainsubjects during Soc.Am.]. This model,which has beensuccessfully applied to several the courseof an experimentalsession. In the currentmodel, observed monauralpsycboacoustical experiments, was extendedby an additional changesin performanceare accounted for by assuminga singleexponen- binauralprocessing unit. It consistsof a filterbank,half-wave rectifier, tial adaptationprocess. This process, which describes the adaptive state of low-passfilter, and adaptation loops, which model the temporalprocess- thesubject, determines the decision criteria and context (effective stimulus ing. The binauralprocessing unit detectsthe interauralcorrelation and range)used in the modelat a given point in time. From the dynamic makes decisions based on Ihe difference between the signals from both decisioncriteria and effective range, and knowledgeof the underlying ears.Masked thresholds in the NoS•r and N•rSo configurations,obtained sensitivityto localizationcues, the modelpredicts mean response, bias, as a functionof noisemasker frequency and bandwidth,were simulated andresolution. The modelpredictions are in goodagreement with results and comparedto new expedmerttalmeasurements. The dependenceon from a relativelyla•ge body of experiments,including experiments in interauraldelay and interaural decorrelation of the noisemasker was also whichthe numberand rangeof stimuliwere varied. modeledand compared to datain the literature.In general,model simula- 3411 J. Acoust.SOC. Am., Vol. 97, No. 5, Pt. 2, May 1995 1291hMeeting: Acoustical Society of America 3411 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp tionsagree well with the main features seen in themeasurements. [Work modulationrate (250 Hz), a singleimage was perceived. Observers were supportedbyDFG (Ho 1627/1-1) and by NIDCD (Grant DC00100).] sensitiveto the interauralmodulation phase with nearperfect discrimina- tionof homophasicfrom antiphasicconditions. Results are discussedin termsof an FM-to-AM transductionmechanism. [Work supported by NIH 1:45 andAFOSR.] 5pPP3.The index of interauralenvelope correlation: Normalized cross-covariance or normalized cross correlation? Leslie R. 2:30 Bernsteinand ConstantineTrahiotis (Ct•. for Neurological Sci. and SurgicalRes. Ctr., Dept.of Surgery,Univ. of ConnecticutHealth Ctr., 5pPP6. The segregationof SAM 4-kHz targets from SAM 2-kHz Farmington,CT 06030) distractors on the basis of interaural envelope delay, R. H. Dye (ParmlyHear. Inst., LoyolaUniv., 6525 N. SheridanRd., Chicago,IL Thisstudy principally evaluated whether the normalized cross covari- 60626) ance(Pearson product-moment correlation) or thenormalized cross corm- lationdescribes discriminability of changes in interauraldisparities con- A stimulus-classificationparadigm was used to examinethe extentto veyedby thestimulus enveloped. In a four-interval,two alternative task, whichjudgments of thelaterality of 4-kHztargets, sinusoidally amplitude listenersdetected which intervalcontained a 4-kHz tone addedantiphasi- modulatedat 200 Hz, were influencedby 2-kHz distractorsthat were callyto diotic,200-Hz-wide, noise (NoS•r). The "nonsignal"intervals modulatedat ratesranging from 50 to 400 Hz. On eachtrial, the target was containedthe toneadded homophasically (NoSo). Discriminability (d') presentedwith one of tenenvelope delays (ranging from -250 to +250• was measured as a function of S/N for values between -30 and +30 dB in 50-/•ssteps), as was the distractor. Each test interval was preceded by a (really!).For all S/N's,overall level was 70 dB SPL.Listeners' perfor- dioticpresentation of thetarget alone. The durationof the signalswas 200 mancewas very well accountedfor by thenormalized cross correlation but ms. Duringa blockof 100 trials,each combination of target-distractor not the normalizedcross covariance. Additionally, listeners were testedin delay was presentedonce. The relativesalience of the envelopedelays a "direct"discrimination task where changes in envelopecorrelations (Ap) cardedby thetarget and the distractor was assessed by theslope of thebest wereproduced by "mixing"two independentGaussian noises. Although linearboundary between left andright responses. Two listenersgave in- Ap'sat threshold(d'=l.0} obtainedfrom the two taskswere similar, the creasingweight to the targetas the differencebetween the targetand psychometricfunctions obtained with the direct discrimination task were distractormodulation frequencies increased, but weighedthat targetand moresteep. Discussion will includehow the normalized cross correlation distractorequally when both were modulated at 200 Hz. Twoother listen- of the envelopeaccounts for classicdata concerning discriminability of ersgave increasing weight to the2-kHz distractoras modulation frequency interauraltime differencesat high frequenciesas a functionof depthof increased,as thoughits relative salienceincreased with "numberof modulation.[Work supported by NIH DC02103.] looks."These data will be comparedto measuresof binauralinterference thathave been obtained for similarstimuli. [Work supported by NIH.] 2:00 2:45 5pPP4.Precedence and plausibility.William A. Yostand Sandra I. Guzman (ParmlyHear. Inst., Loyola Univ. Chicago,6525 N. Sheridan 5pPP7.Precision of soundlocalization measured by a reachingtask. Rd., Chicago,IL 60626} Daniel H. Ashmead,Xuefung Yang, Robert Wall, and Kiara Ebinger (Dept.of Hear.& SpeechSci., Vanderbilt Univ. Med. Ctr.,Nashville, TN The "Cliftoneffect" JR. K. Clifton,J. Acoust.Soc. Am. 82, 1834- 37232-8700) 1835 (1987)] was studiedin a sound-deadenedroom with sevenloud- speakers.One loud speaker produced a source click while other loudspeak- This studyvalidates a reachingmeasure of soundlocalization for sub- ersproduced delayed copies simulating echoes (delays: 2-30 ms).Each sequentapplication to children.Seven adults reached for broadband sound combinationof sourceand echoesis one click event and was presentedas sourceswhile handposition was measured to within 2 min. Soundscame a train of click events(1-20 click events}.A train was presentedto listen- from 18 regionsin frontalreaching space, with the loudspeakermoved erswho made two judgments for theLAST clickevent presented: (1) The awayjust afterstimulus offset. In the "visual"condition subjects watched numberof loudspeakerswhich produced sounds for the lastclick event, until the soundended, then closedtheir eyes and reached.In the "audi- and(2) theloudspeaker location for eachperceived source. "Catch trials" tory" conditionsubjects were blindfolded.Precision of soundlocalization were introducedto make sure listenersused all possibleresponses and wasestimated by comparingvariability in the visualand auditory condi- were able to locatethe loudspeakersources. When more than 10 click tions:s = sx/-•v.Estimates were computed forhorizontal angle, ver- eventswere presented, a switch in conditionswas introduced between the tical angle,and distance for eachtarget location. Results agreed reasonably 10thand 11thclick event.If the switchwas plausible for a naturalsource well with conventionalmeasures. For targetsstraight ahead at ear level, andits echoes,responses indicated that listeners processed delayed clicks horizontal s=2.6 ø, vertical s=5.0 ø, and distances=9.5%. Systematic as echoes.If the changewas iraplausible, then responses after the switch variationsoccurred across target locations. This reachingtask is a rapid, changedindicating listeners processed all clicksas if theywere sources naturalisticway of measuringthree-dimensional sound localization. [Work ratherthan echoes. [Work supported by NIH andAFOSR.] supportedby DOE andNIH.] 2:15 3:00 5pPPS.Lateralization of high-frequencyFM tonesand frequency 5pPP8. Virtual auditory reality reduced to the bare essentials. sweeps. KouroshSaberi (Psychoacoust.Lab., Dept. of Psychol.,Univ. William Morris Hartmannand Andrew Wittenberg (MichiganState of Florida,Gainesville, FL 32611) Univ.,Dept. of Phys.,East Lansing, MI 48824) Lateralizationthresholds were measuredin three experiments.In ex- Successfulimaging of real soundsources by headphonescan be done perimentI, thresholdsmeasured for sinusoidalFM with carriersof 3 or 4 by measuringfree-field head-related transfer functions (HRTF) using small kHz and modulationrates from 50 to 800 Hz were comparableto those microphonesin the ear canalsand theninverse filtering by the headphone measuredfor sinusoidalAM stimuli.Lowest thresholds(at 71% correct) response.A simpleralternative to this standardprocedure is described were about100/.•s, obtainedat modulationrates of 300-350 Hz. In ex- wherea listener,with smallmicrophones in the ear canals,wears open-air perimentII, a 300-mstone was linearly swept in frequencyfrom 2 to 5 headphonesthroughout the experiment.A synthesizedvowel is played, kHz. The slopeand intercept of the time-frequencyfunction were random- first from a loudspeakerand then from the headphones.The headphone ized by 10% on eachobservation. Lateralization thresholds were about 50 signal is adjustedso that the amplitudesand phasesof the harmonics /•s. Unequaltime-frequency slopes at the two earsproduced a senseof measuredwith the small microphonesare the sameas thosefound when motion.In experimentIII, a sinusoidalFM waspresented to one ear and a the loudspeakeris sounding.The techniqueis successfulin that listeners sinusoidal AM to the other ear. When the FM and AM had the same cannotdistinguish between real and virtual sources.It lacksthe flexibility 3412 J. A½oust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3412 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp of theHRTF technique, but it allowsan experimenter to study the most that ADP fine structureis largelygenerated in the overlaparea of the interestingpsychoacoustical questions about sound localization and exter- travelingwaves for the primary tones,and the effectsof reemissionsfrom nalizationusing an exper•meotaltechnique that is simplerand probably the 2fl -f2 areaare minimal.A largevariance was observed in thebest morereliable. [Work supported by theNIDCD and by theNSF Research L 1/L2 ratio,ranging from -7.5 to 20 dB bothacross and within subjects. Participationfor UndergraduatesProgram.] [Worksupported by NIDCD.] 3:15-3:30 Break 4:15 5pPPI2. Pure-tone thresholds and cubic distortion product otoaconsllc emissionsin the chinchilla following carboplatin 5pPP9. Cochlearacoustic reflectance and traveling wave delay. treatment. Brenda M. Jock, Kristeo-LynPetriclio, Lori G. Aldrich, BarryP. Kimberley(Dept. of Surgery,Univ. of Calgary,3330 Hospital Ann R. Johnson,Roger P. Hamernik.and William A. Ahroon (Auditory Dr. N. W., Calgary,Alberta T2N 4NI, Canada), Greg Shaw (Univ. of Res.Lab., State Univ. of New York,Plattsburgh, NY 12901) Calgary), ChristopherSbera (EatonPeabody Labs.), and Jont B. In the chinchilla,carboplatin has an unusualototoxic effect on the Allen (Bell Labs.) sensoryepithelium of the cochlea[Takono et aL, Hear.Res. 75, 93-102 Inner ear acousticimpedance and reflectance,SFOAEs, DPEs, and (1994)].Twelve chinchillas were treated with a singleIP or IV injection PTI•swere measuredwith a calibratedprobe situated in the ear canalof (50 or 75 mg/kg)of carboplatin.Baseline auditory evoked potential au- normal-hearingsubjects. The useof a calibratedprobe allowed for the diogramsand cubic distortion product otoacoustic emissions (3DPE) were conversionof the SFOAE recordingsinto reflectance.In a numberof obtained on each animal. Threshold and 3DPE functions were also ac- subjects,low stimuluslevels results in ripplingof the reflectance.The quiredat regularintervals between one hour and 30 dayspost-injection. phaseslope of the acousticreflectance was foundto be a linearover a The sensoryepithelium of the cochleawas evaluatedusing the surface narrowrange of frequencies.This slopeis takenas equivalentto the trav- preparationmethod. Anatomical analysis indicated that the carboplatin elingwave delay to thecorresponding frequency(ies). Traveling wave de- causedrelatively severe but scatteredlosses of inner hair cells (IHC) lay estimates(reflectance phase slope) however did notchange as stimulus throughoutmost of the cochlea.The outer sensorycell populationwas level rangedfrom 50 to l0 dB SPL. This is in contrastto previoustraveling intact and the cells appearednormal at the level of the light microscope. wave delayestimates using DPEs wheredelay increasedwith a decreasein Despitethe IHC pathology,which alsoincluded vacuolization in the area stimuluslevel [Kimberleyet aL, J. Acoust.Sue. Am. 94, 1343-1350 of the IHCs, evoked potential thresholds,measured at the level of the (1993}].The discrepancy between DPE-based and SFOAE-bascd estimates inferiorcolliculus were very nearnormal and 3DPE functionsshowed very of travelingwave delay is discussed. littlechange. [Work supported by Bristol-MyersOneology Division and SUNY-Plattsburgh.] 3:45 4:30 5pPP10. Modeling distortion product otoacousfic emission fine structure in humans. Carrick L. Talmadge,Arnold Tubis, Pawal 5pPP13. Spontaneousand click-evokedotoacoustic emissions of the Piskorski(Dept. of Phys.,Purdue Univ., West Lafayette, IN 47907),and frog inner ear: Spectral characteristics and temperature GlenisR. Long (PurdueUniv., West Lafayette, IN 47907) dependence.Bert Maat, Pim vanDijk, andHero P. Wit (Inst.of Audiol., ENT Dept. Univ. Hospital Groningen,P.O. Box 30.001, 9700 RB The presenceof fine structurein distortionproduct otoacoustic emis- Groningen,The Netherlands) sions(DPOAEs) in humansand otherspecies provides important clues concerningthe underlyingmechanisms which give rise to this structure. Spontaneousotoacoustic emission (SOAE) and click-evoked otoacous- Recentexperimental findings of our groupindicate that (i) synchronous tic emission(CEOAE) measurements were performed in frogs(Rana es- evokedemissions, hearing threshold microstructure, and the fine structure culenta).The SOAE and CEOAE measurementsfollowed each otherre- of DPOAESin eachear appearto correspond,(ii) the fine structureof peareally,while the frog's body temperaturewas changedat a rate of higher-orderDPOAEs, i.e., fl-n(F2-fl), n>2 dependson the approximately0.1 øC/min.in somesessions, only SOAE measurements DPOAE frequency,and (iii) DPOAEswith n<-1 do not have well- wereperformed. The SOAE andCEOAE spectrawere closely related: The formedfine structure.These data will be usedto contrastand compare two spectraof CEOAE containedthe same peaksas thoseobserved in the distinct models of DPOAE generation,one in which the fine structure relatedSOAE spectrum.It seemsthat click evokedemissions in the frog arisesfrom the interactionsin the strongoverlap region of thefl andf2 are synclxronizedspontaneous emissions. The click-evokedresponses activitypatterus (near the f2 tonotopicplace), and one in whichthe fine showa nonlinearcompressire amplitude growth with the stimulusinten- structurearises from reflections of the distortionproduct near its tonotopic sity. As functionof temperature,various emission modes, and complex location.The data stronglyfavor the later model. amplitudepatterns were observed for bothtypes of emissions. 4:00 4:45 5pPP11.Fine structureof 2f•-f2 acousticdistortion product: Effect 5pPP14. Enhanced cochlear responsesafter sound exposure. of LIIL2 ratio. Ning-ji He and RichardA. Schmiedt (Dept. of YvonneM. Szymkoand JozefJ. Zwislocki (Inst. for SensoryRes., Otolaryngol.and Commun.Sci., Medical Univ. of SouthCarolina, 171 SyracuseUniv., Syracuse, NY 13244) AshleyAve., Charleston,SC 29425-2242) Hensen'scell alternatingpotentials were recorded in the gerbilcochlea The fine structureof the 2f,-f2 acousticdistortion product (ADP) by meansof the approachdeveloped previously in this laboratory.An wasmeasured in a groupof normal-hearingsubjects with differentcom- intensityseries of magnitudeand phase transfer functions (TFs) andco- binationsof primary levels (LI and L2). The frequencyratio chlearmicrophonic (CM) TFs from 125 Hz to 16 kHz were obtainedat (f21f•,f2>f•) was1.2, and the f2 frequencywas swept from 1781 to 40-90 dB soundpressure level (SPL) by meansof frequencysweeps. 2300 Hz in • octavesteps. In condition1, LI wasfixed at 50 dB SPL Subsequendy,the samefrequency sweeps at either80, 90, or 100dB SPL while L2 variedfrom 30 to 75 dB SPL in 5-dB steps.In condition2, L2 were delivered to the ear for 10-40 min. CM, Hensen'scell TFs, and EP was fixed at 50 dB SPL and LI was vatned as in condition I. For a fixed were monitoredperiodically post-exposure. Hensen's cell responses L 1, an upwardfrequency shift was evident in theADP fine structureas the showedenhancement within 40-50 rain post-exposureand a phaselead. L2 level increased,whereas for fixedL2, a downwardfrequency shift in Therewas no correlationbetween changes in peakresponse and changes in the ADP patternwas observablewith an increasingL 1. These results receptorpotential or EP. The responseenhancement and its associated supporta vectorsum computer model for theADP finestructure [Sun phaselead is explainedwith the help of Zwislocki'scochlear model [Me- et al., J.Acoust. Sue. Am. 96, 2166-2174,2175-2183 (1994)], suggesting cltanicsand Biophysics of Hearing,edited by P. Dallos(Springer-Verlag, 3413 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3413 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp Berlin,1990)]. Since Hensen's cells cannot generate receptor potentials by first-and second4order Wiener kernels were fully calculated,while for the themselves,and theirAC potentialshave been shown to be directlypro- 3rd- to 10th-orderkernels only thediagonals (also known as polynomial portionalto thoseof OHCs, the measuredenhancement appears to reflect correlationfunctions) were computed. The datafor fibersabove 500 Hz enhancedOHC responses. [Work supported by NIDCD.] could be describedby a BPNL sandwichmodel. A new least-squares method was used to determine both filter functions in the model from the 5:00 Wiener kernels. Preliminary analysisshowed that responsecomponents couldbe foundin kernelsup to theorder of 5. This suggeststhat the degree 5pPPI5. Representation of sinusold "ramps" and "damps" in of the nonlinearityof the frog inner ear is at most5. auditory-nervefibers of the goldfish, R. Fay, M. Chronopoulos (Parmly Hear. Inst., Loyola Univ. Chicago,6525 N. SheridanRd., Chicago,[L 60626), and Roy Patterson(MRC Appl. Psychol.Unit, CambridgeCB2 2EF,England) Earlier,behavioral data was presented showing that goldfish perceive 5:30 repeated,asymmetrically shaped 400-Hz tonebursts (ramps and damps) 5pPP17, Binaural lateralization and discrimination in MS and CVA qualitativelyas humans do: Ramps are more tonelike than damps JR. Fay andR. Patterson,J. Acoust.Soc. Am. 95, 2941 (A) (1994)].Ramps have patients, VeredAharonson, Miriam Furst (Dept.of Elec.Eng.-Systems, slowrise and relativelyfast fall envelopes.Damps are rampsplayed back- Facultyof Eng., Tel Aviv Univ., Tel Aviv, Israel 69978), and Amos D. ward. Single auditory-nervefibers were recordedin responseto the same Korczyn (SacklerSchool of Medicine, Tel Aviv Univ., Tel Aviv, Israel ramp and damp stimuli usedin the behavioralstudies. Spike times were 6997S) recordedfor two presentationsof six, 3-s stimuli:Ramps with 25-, 35-, and 45-ms rise times and 5-ms fall times,and thesestimuli playedbackward Most previousstudies on MS patients'binaural performance reported (damps),presented at severallevels. Tuning was describedusing REV- similarperformance according to intensityand time cues,or abnormality COR analysisand by spikecount functions of frequencyat severallevels. onlyfor interauraltime differences.In thisstudy, combined lateralization Responsivenesswas defined using the coefficientof synchronization(R) and discriminationtests on both MS and CVA patientsdetected other overthe carrierperiod, the numberof spikesevoked (N), andthe statistic Z whereZ = R21V.For most fibers, R, N, andZ weregreater for ramps than phenomena.Lateraliza6on and discriminationability were measureddur- for thecorresponding damps. This neuralbehavior is quantitativelysimilar ing the samesession for eachpatient, with clicks,high, and low narrow- to thebehavioral results. The differentialperception of rampsand damps is bandnoises. Lateralization tests arbitrarily presented interaural time and representedwithin individual primary afferents. The originsof thesephysi- intensitychanges in 9 levelsscale across the head.Adaptive 212AFC ologicaldifferences will be discussed.[Work supported by the N1DCD.] proceduredetermined jnd's. Ten CVA and 5 MS patientsperformed ab- normallyin someof thetests, and can be crudely divided into three groups: The firstgroup performed normally in responseto clicksand low frequen- 5:15 cies,and failed only in high frequenciesstimuli, in bothlateraliv•afion and 5pPP16. Polynomial correlation used to estimate the degree of ind. The secondgroup performed abnormally in both testsand for all nonlinearity of the frog inner ear system. Pim van Dijk (Inst. of stimuli.The third grouphad normaljnd's for all stimuli.However, for Audiol.(KNO), Univ. HospitalGroningen, P.O. Box 30.001,9700 RB somestimuli, those patients failed in thelateralizafion tasks, only in oneof Groningen,The Netherlands) theinteraural changes--either time or intensity.These results indicate that The nervefiber response to Gaussiannoise was measured in the Ameri- criteriaused for jnd tasksare not applicable in lateralizafionand that time canbullfrog (Rana Catesbeiana). By crosscorrelating the stimulus and the andlevel differencesare estimatedindependently along the auditorypath- response,Wiener kemelsof the frog innerear systemwere obtained.The ways. SATURDAY AFYERNOON, 3 JUNE 1995 MEETING ROOM 16, 1:00 TO 3:15 P.M. Session5pSA Structural Acousticsand Vibration: Fuzzy Structures Victor W. Sparrow,Chair GraduateProgram in Acoustics,Pennsylvania State University, University Park, Pennsylvania16802 ContributedPapers distributedwith respectto naturalfrequency. The exactform of the distri- butionis shownto be relativelyunimportant as longas it is smoothand 5pSAI. An asymptoticanalysis of the added damping effect of a continuous.The eftL'ctsof the systemof attachments,in responseto distribution of fuzzy attachments with steady state excitation. steady-stateexcitation of the masterstructure to whichthey are attached, DanielA. Russelland VictorW. Sparrow (GraduateProg. in Acoust., are obtainedthrough an analysisof the inputmechanical impedance. The PennState Univ., UniversityPark, PA 16802) real partof this impedancerepresents the effectiveadded damping. Two asymptoticlimits are investigated.In the first limit, the numberof attach- In the currentstate of fuzzy structuretheory, it is recognizedthat the mentsbecomes very large (N--•oo), and the impedance sum approaches an primaryeffects of a fuzzy substructureare a frequency-dependenteffect asymptoticintegral. In the secondlimit, the dampingratio of the attach- addeddamping and a frequency-dependenteffective added mass. In this mentsbecomes very small (•--•0), andthe asymptotic integral reduces to a paperthe fuzzy substructureis modeled, in accordancewith currentprac- simplealgebraic expression. Comparison of the impedancesum and the tice, as a systemof independent!-DOF oscillatorswhose massesare asymptoticexpression, in light of theproduct N•, suggeststhat the simple 3414 d. Acoust.Soc. Am., Vol. 97, No.5, Pt. 2, May1995 129thMeeting: Acoustical Society of America 3414 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp asymptoticexpression is valid for steady-stateexcitation, as long as 2:00 •<0.01, andthe product N•>2. [Worksupported by ONR.] 5pSAS.Coupling between flexural and membranewave types due to multi-degreesof freedomand rotationalfuzzy attachments. Daniel A.Russell and Victor W. Sparr.o,w (Graduate Prog. in Acoust., Penn State 1:15 Univ., UniversityPark, PA 16802) 5pSA2. Averageresponse of an infinite plate on a random elastic In currentfuzzy stracturetheory, the fuzzy substructureis generally foundation.Joseph A. Turnerand Richard L. Weaver (Dept.of Theor. modeledas a systemof independentI-DOF oscillatorsattached to the andAppl. Mech., 104 S. WrightSt., Univ. of Illinois,Urbana, IL 61801) masterstructure. Several assumptions are usuallymade. Firstly, while the attachmentsare appliedto oneside only of the masterstructure (plate or The averageresponse of infinitethin plateswith attachedrandom ira- shell),the effectsof asymmetricloading are ignored.In thispaper, it is parlancesis examined.The addedimpedance, which representstypical shownthat the asymmetricloading may providea couplingmechanism heterogeneitiesthat might occur on complex shells, provides light coupling betweenflexural wavesand membranewaves in platesand shells,thus betweenthe threepropagation modes. The problemis formulatedin terms altering the predictedadded dampingefi•ct of the fuzzy substructure. of the Dysonequation which governs the meanplate response. It is solved Secondly,until now the motionof the attachmentsis usuallyrestricted to withinthe assumptionsof the Keller(smoothing) approximation which is only one translationaldirection. This paper considersthe possibilityof valid whenthe heterogeneitiesare weak. Scatteringattenuations are de- couplingbetween wave typesin platesand shellswhen the fuzzy attach- rived for each propagationmode. The specificcase of delta-correlated ments are allowed to move in three translational directions, as well as springsprovides a simpleintuitive result for a statisticallyhomogeneous rotationalmotion about their attachment points. Furthermore, the effects of plate.The attenuationof one wave type due to couplingto anotheris these new attachmentmotions are analyzed using a wave impedance/ shownto be proportionalto the modaldensity of the otherwave type. Thus dispersionrelation approach. [Work supported by ONR.] the attenuationof extensionaland shearwaves is predominantlydue to modeconversion into flexural waves and is proportionalto thelarge modal densityof flexuralwaves. The flexuraldegrees of freedomserve as a sink 2:15 for theenergy of themembrane modes and constitute for theman effective fuzzy structure.A similar result is expectedfor the more complicated 5pSA6. Responseof a fuzzy structure in terms of the impulse submergedshell case.A discussionof diffuseenergy transport on sucha responsefunction. G. Maidanikand J. Dickey (CD/NSWC,Code 703, platewill alsobe presented.[Work supported by ONR.] Bethesda,MD 20084) A masterstructure is definedin termsof a knownand proper impulse responsefunction g•(x]x',•o), where x isthe spatial variable that spans the 1:30 masterstructure and o• is thefrequency variable. The response u=(x,oJ) of the masterstructure to the externaldrive p•(x,•o) is statedin the form 5pSA3. Vibrational responseof a simple oscillator attached to an o•(x,•o)=J'g•(x[x',o}dx'pe(x',oJ}, where dx is anelemental "volume" in elastic structure. DouglasM. Photiadis,J. A. Bucaro, and Brian H. the x domain.An ensembleof appendagesis attachedto the masterstruc- Houston (Naval Res.Lab., Washington,DC 20375-5350) ture. The ensembleand its attachmentconfigures an appendedmaster structure.The response n(x,•o) of theappended master structure is statedin The effect of many internaldegrees of freedomon the vibrationof theform o(x,oJ)=.fg•s(XlX',•o)dx' pe(x ',oJ), where g•s(X[X',O•) is theim- elasticstructures has been of great recentinterest; several theories have pulseresponse function of theappended master structure and it is assumed predicteddamping effects arising from associatedinternal resonances. As thatthe externaldrive remains unchanged. In the precedingequation it is an initialeffort to explorethis phenomena experimentally, the behaviorof impliedthat g•s(x[x',o•) is properly derived; indeed, without this propriety a singlesuch oscillator attached to ribbedcylindrical shell section has been theequation is meaningless.An ensembleof configurationsdefines a mas- measured.The singleoscillator has been foundto give rise to a fairly ter structurethat is variouslyappendaged. When the ensemble of configu- broadbandresonance structure, with a bandwidththat paradoxicallyin- rationsis statisticalized,a fuzzy structureis defined.Using this equation creaseswith decreasingfrequency. These results, along with the physical anddesignating statistical averaging over configurations by angularbrack- interpretationand modeling, will be discussed. ets, one obtainsthe response(u(x,o•)) of a fuzzy structurein the form (o(x,•o))=$(g•s(xlx',o•))dx'pe(x',o,).In (g=s(xlx',o0) only statistical variationsin the propertiesof the appendagesand their attachmentsare 1:45 involved;a proper g=s(X]X',m) is not committed to o(x,o)and pe(x,o•). Thus it is arguedthat the last equationis an acceptablesolution to the 5pSA4. Eigenstatistics in rectangular membranes with point response(u(x,•o)) of a fuzzystructure. scatterers. RichardL. Weaver (Dept.of Theor.and Appl. Mech.,Univ. of Illinois,104 S. WrightSt., Urbana, IL 61801) Conventionalwisdom holds that a finite reverberantsystem with cha- 2:30 otic ray trajectorieswill have, at high frequencies,eigenvalue statistics 5pSA7. Prediction of scattering cross sections using averaged identicalto thoseof theGaussian orthogonal ensemble of randommatrices models. DouglasM. Photiadisand David Hughes (NavalRes. Lab., {GOE). It alsoholds that a nonchaoticsystem will havesimple Poissonian Washington,DC 20375-5350) statistics.Recent experimentson the eigenvaluesof elastic blocks with angledcuts, recent calculations of theeigenfrequencies of membranes with The presenceof internalstructure can greatly alter the acousticbehav- staircaseslike jagged boundaries and the eigenfrequencies of a rectangular ior of elasticstructures. Even in relativelysimple systems, it is necessary domainwith a singleisotropic point scattererhave, however, found GOE to employapproximate models, effectively averaging out unwanted detail. statisticseven in thesequasi-integrable systems•even though all raysin Somephenomenological aspects can be easilyobtained in this way pro- suchsystems are nonchaotic.In this work the rectangulardomain with videdthe "base" structureis not too complicated.For example,the locus isotropicpoint scatterers is studiedfurther. It is shownthat the long-range of peaksin thescattering cross section as a functionof frequencyand angle levelrepulsion in thissystem is not in preciseaccord with the predictions canoften be predictedin a deterministicmanner, but estimating. the actual of the CJOE,nor is the long range spectralrigidity. CJOEdoes, though, scatteringlevels requires more sophisticated modeling. One approachto correctlydescribe the shortrange statistics. A quantitativeprediction for this modelingproblem is to employa "fuzzy" structuresparadigm in therange in whichGOE appliesis advancedbased upon the lifetimeof a which a Neumannseries involving the randomaspects of the internal rayagainst mixing--i.e., based upon the cross section of thescatterer. This structureis averaged.A more sophisticatedapproach involves directly predictionis corroboratedby numericalcalculations of theeigenfrequen- constructingand approximatingequations for the desiredaverages; em- cies.[Work supported by NSE] ployingthe Dyson and Bethe4Salpeter equations of randommedia theory. 3415 J. Acoust.Soc. Am., VoL97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3415 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp Thesetechniques have been applied to predictthe scattering cross section 3:00 froman irregular fibbed structure. The results will bediscussed and com- pared. 5pSA9.Free vibrationof liquid-filledcomposite shells of revolution. Z. C. Xi, L. H. Yam,and T. P. Leung (Dept.of Mech.and Marine Eng., 2:45 HongKong Polytech. Univ., Hung Hom, Kowloon, Hong Kong) 5pSA8.Electrodynamic reciprocity method for vibrationstandards. Li-FengGe (AnhuiBureau of Tech.Supervision, 30-Ma An ShahRd., As compositematerials are increasinglyused in aerospace,marine, Hefei,Anhui 230001, People's Republic of China) civil powergenerating, petrochemical, and chemicalindustries, the inter- actionof fluid andcomposite shells of revolutionhas been an activesub- In a previouspaper, a reciprocitycalibration formula different from the Levy-Bouche'sis derived[L.-F. Ge, Proceedingsof the XIII IMEKO ject in the area of structuraldynamics. In this paper,a semianalytical WorldCongress, 2606-2610 (1994)]; the latterhas been regarded as a procedurewas presented for predictingfree vibrationcharacteristics of standardmethod [ISO 5347-0,1987; ISO/DIS 5347-20, 1990]. The new liquid-filledcomposite shells of revolution.A newunaxisymmetric conical formulais S= (gT/jto)112 (V/ms-2), where T is themean of then'ansfer frustum element was derived based on the first-order shear deformation admittanceratio, T•=M•/(Y•-Y o) and R is the voltageratio for the theory.The elementconsiders both the displacement in thecimumferential typicalthree-transducer-two-experiment procedure, in whichan electrody- directionand the rotationaround the meridianof the shell.The coupling namictransducer serves as reciprocalone. This methodis suitedto the betweensymmetric and antisymmetric modes is takeninto accountin the low- andmid-frequency ranges, and most accurate at 100-1000 Hz. This formulation.Reduced integration was employed to avoid"shear locking." paperreveals that a coefficientof variation,i.e., ratioof standarddeviation Numericalexamples were given for free vibrationsof liquid-filledlami- of T• to its meanvalue, can be viewedas a reciprocityindex of suchan natedshells of revolutionwith various types of boundaryconditions. Com- electrodynamiccalibration system including two transducersand a solid parisonsof theresults predicted by the presentpaper with thoseavailable massmedium. An index smallerthan 0.5% indicatesthat the systemis in the literaturewere made.The effectsof the liquid depth,the ratio of betterreciprocal, and can be calibratedmore accurately. At frequencies higherthan about 3000 Hz, nonlinearproblems, such as stress wave effect massdensity of the liquidto thatof the shell,circumferential wave num- and resonance,become pronounced, and shouldbe considered;a better ber, thicknessto radiusratio, ply angle,and stackingsequence on natural way wouldbe to applyother more available methods, such as the laser frequencyof wetshells were discussed. [Work supported by RC, HK Poly interferometryand piezoelectric reciprocity method. U.] SATURDAY AFTERNOON, 3 JUNE 1995 CONGRESSIONALHALL A} 1:00TO 5:00P.M. Session5pSC SpeechCommunication: Consonants, Vowels, and Voice(Poster Session) Peggy B. Nelson, Chair Centerfor Auditoryand SpeechSciences, Gallaudet University, Washington, DC 20002 ContributedPapers All posterswill be on displayfrom 1:00a.m. to 5:00 p.m. To allowcontributors an opportunityto seeother posters, conu'ibutors of odd-numberedpapers will be at theirposters from 1:00to 3:00p.m. and contributors of even-numberedpapers will be at theirposters from 3:00 p.m. to 5:00 p.m. To allowfor extendedviewing, posters will be on displaybeginning at 8:00 a.m. 5pSC1. Interactions between acoustic dimensionscontributing to the intensity trade-off between perceptionof VOT and aspiration.The results perception of voicing. Michael D. Hall, KatharineDavis, and Patricia indicate that F0 and VOT/aspirafion amplitude may contributeto two K. Kuhl (Dept. of Speechand Hear. $ci., WJ-10, Univ. of Washington, distinctsets of pemeptualanalyzers. Implications for phonemeperception Seattle,WA 98195) will be discussed.[Work supportedby NIH.] It is well known that several dimensions contribute to the Classification 5pSC2.Prediction of obstruentspectra frøm the slope of preceding of stopconsonants as voicedor voiceless.Three Gamerspeeded classifi- and following second formant transitions. Gary Weismet, Vidya cationexperiments evaluated the nature of perceptualinteractions between Guhan,and Ray D. Kent (Dept. Commun.Disoral. and WaismanCtr., suchdimensions. Specificaily, the experiments exanUned the potential in- Univ. of Wisconsin-Madison, 1500 Highland Ave., Madison, WI tegralitybetween pairs of three critical dimensions--voiceonset time 53705-2280) (VOT), aspirationamplitude, and fundamental frequency (F0) at theonset of voicing.Only within-category (/ks/) syllablestimuli were used to elimi- There is evidencethat the slopeof secondformant (F2) transitions natephonetic classification as a basisfor subjects'responses. Evidence was providesan index of the severityof speechmechanism involvement in found for the asymmetricseparability of VOT and F0; while variability motorspeech disorders [Weismet et al., J. Acoust.Soc. Am. 91, 1085- alongF0 significantlyinfluenced VOT classificationspeed, variability 1098(1992)]. From an articulatoryperspective, the slopeof the F2 tran- alongVOT did not similarlyinfluence F0 classification.A similarpattern sition is an ordinalindex of the rate of changein vocal tract configuration. of asymmetricseparability for F0 and aspirationamplitude was demon- It was hypothesizedthat, for singlewords, these F2 slopeswould predict strated,where aspiration variability did not interferewith F0 classification. quantitativespectral characteristics of adjacentobstments, under the as- In contrast,VOT and aspirationamplitude were completelyintegral, with sumptionthat the rate of changein vocal tract configurationduring a variability along either dimensioninfluencing classification speed along vocalicsegment would influence the articulationof a precedingor follow- the otherdimension. Furthermore, performance accuracy reflected a time- ing obstruent.Quantificafion of obstmentspectra was achievedby means 3416 d. Acoust. Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3416 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp of spectralmoments, which were regressed on F2 transitionslopes for a guishing,e.g., Weplay dominoes.from Weplayed dominoes. Moreover. groupof normallyarticulating men and a groupwith amyotrophic lateral someVOT, CD, andVGD differenceshave little linguisticor evenper- sclerosis,a degenerative motoneuron disease typically associated with dys- ceptionfunction. Thus Ip,t.k/show dursttonal differences, but these cannot arthria.Results partially confirmed the hypothesis for bothgroups of sub- readilybe shownto affectstop place perception. [Work supported by NIH jects;the findingswill be discussedin termsof separatetreatment of GrantNo. HD-01994.] vocalicand obstment segments in a modelof kpeechintelligibility. [Work supportedby NIH.] 5pSC6. Measuring speaker normalization of fricatives using three methods. Keith Johnson,Shuhui Peng, and ElizabethStrand (Dept. of 5pSC3. Acoustic-to-articulatorymapping of fricatives. Edward L. Linguistics,Ohio StateUniv., 222 Oxley Hall, 1712 Nell Ave., Columbus, Riegelsbergerand Ashok K. Krishnamurthy(Dept. of Electr.Eng., Ohio OH 43210-1298) State Univ., 2015 Nell Ave., Columbus,OH 43210) Speakernormalization effects using condnua from "sue" to "shoe" This researchconsiders the acoustic-to-articulatorymapping of frica- and threeexperimental tasks: Identification, goodness ratings, and direct tire speech.By incorporatingadditional knowledge about fricative pro- prototypeestimation are compared.The continuawere formedby concat- duction,perception, and dynamicsinto the mappingscheme, improved enatingsynthetic fricalive noises ranging from [s] to • with the vowel performancemay be achievedover standard acoustic-to-articulatory map- portionof "sue" or "shoe"produced by a male and a female speaker. pingtechniques. A hybridtime-frequency domain articulatory synthesizer Speakernormalization was measured in the identificationtask as a bound- and numericaloptimization techniques are appliedto sleady-state,un- ary shift betweenresponses to the "male" sfmuli and the "female" voicedfricatives. The work differs from the fricativeinverse mapping stimuli.Comparison of categoryboundaries was also used to measurethe experimentsof SorokinIV. Sorokin,Speech Commun. 14, 249-262 speakernormalization effect in ihe goodnessrating paradigm, where a (1994)]and Shirai [K. Shiraiand S. Masaki,Speech Commun. 2, 111-114 stimuluswas considered to be in the "s" categorywhen the "goodnessas (1983)] in that a fricative-specificlinked codebook is usedto initialize [s]" ratingwas higher than the "goodness as [J]" rating. Speaking normal- optimizationand amplitude sensitive distance measures are used.The fri- izationin the prototypeestimation procedure was measured as the shiftin catire codebookproduces starting configurations for numericaloptimiza- theaverage estimate of the[s] or [J]prototype. Both measures of category tion basedon theirspectral characteristics and their ability to matchfrica- boundaryshift showed substantial speaker normalization effects, while the tion source characteristicsfor a given lung pressure and glottal magnitudeof theeffect in theprototype estimation task, though significant, configuration.The useof amplitudesensitive spectral distance measures is was threeto four timessmaller. However, this smallereffect closelymir- necessaryto accountfor the interactionbetween the tractand the ttow- rorsthe magnitudeof the acousticdifference usually found between male dependentfrication source. Examples of acoustic-to-articulatorymapping andfemale fricative. [Work supported by NIH.] aregiven that compare fricative articulatory models and fricative spectral 5pSC7. Testingthe importanceof talker variability in non-native distance measuresfor the inverse mapping scheme. Acoustic-to- speech contrast training. James S. Magnuson, Reiko A. Yamada, articulatoryperformance is evaluatedin terms of spectraldistance and Yoh'ichi Tohkura (ATR Human Info. Process.Labs., 2-2 Hikaridai, clusteringability. [Work supported by theAFOSR.] Seika-cho,Soraku-gun, Kyoto, 619-02, Japan),and Ann R. Bradlow 5pSC4. Discrimination of synthetic /ba-wa/ by budgerigars (IndianaUniv., Bloomington,IN 47408) (Melopsittaeusundulatus). MichaelL. Dent,Elizabeth F. Powell,Alisa Pierce,and RobertJ. Dooling (Dept. of Psychol.,Univ. of Maryland, In contrastto resultsof trainingwith stimuliproduced by 5 talkers, CollegePark, MD 20742) Lively et el. [J. Acoust.Soc. Am. 94. 1242-1255(1993)] reported that Japaneseadults trained to perceiveEnglish/r! and/1/with stimuli produced The perceptionof speechsounds by animalsprovides important com- by a singletalker failed to improvefrom pretestto post-test,or to gener- parativedata for understandingthe perception of speechby humans.Using alize to novel stimuli.That studywas extendedby training5 groupsof operantconditioning procedures, three budgerigars (Melopsittacus undu- subjectseach with a differenttalker, and by examiningthe retentionof latus)were trained and thentested on theirability to discriminateamong learningafter 3 and6 months.The previousresults were partially repli- tokensof synthetic/ba-wa/speech continua. A "short"(120 ms) anda cate&Although all subjectsshowed significant learning during training, "long" (320 ms) continuumwere constructed,each consistingof l0 subjectsin 3 of the 5 groupsdid not showsignificant improvement in a stimuli. For both the long and the short /ba-wa/ stimuli, budgerigars pretest-post-testcomparison, did not generalizewell to newstimuli, and showeda markedimprovement in discriminationnear the humanphonetic did notshow good retention in 3- and6-month follow-up tests. Subjects in boundary.Similar to humans,budgerigars were significantly less sensitive two of the five groupsimproved significantly from pretestto post-test, to transitionchanges in the long syllablescompared with the shortsyl- generalizedwell to newstimuli, and showed retention comparable to that lables,suggesting that they may be susceptibleto backwardmasking by of subjectstrained with multipletalkers. The resultsindicate that while the syllableof longerlength. Two of the threebudgerigars also showed a multiple-talkertraining leads to consistentlygood results, training with shift in their phoneticboundaries with changesin syllablelength. These stimuliproduced by only one talkermay fail to promotegeneralization to data extend the evidence of similarities between birds and mammals in the new stimuli and talkers under certain conditions. perceptionof speechsound contrasts. [Work supported by NIH Grants 5pSCS.Perceptual training on Hindi dentaland retroflexconsonants DC00198and MH00982 to RJD.] by native Englishand Japanesespeakers. JohnS. Pruitt (Dept.of 5pSC5. Measurement for measurement'ssake: Phonologically Psych.,Univ. of SouthFlorida, Tampa, FL 33620) irrelevant stop voicingdurations. Leigh Lisker (HaskinsLabs., 270 Crown St., New Haven,CT 0651I) Previousresearch has shown that both native English and native Japa- nesespeakers have great difficulty distinguishing the dentaland retroflex Durationaldifferences between voiced and voicelessstops have been stop-consonantsof the Hindi language.However, Japanese speakers per- regularlyreported, and phonologicalvalue has been attributed to someof form much better than English speakers•articularly on voiced- them,i.e., VOT, closureduration (CD), andvoicing-gap duration (VGD). unaspiratedconsonants. This differential performance is thought to be due ThusEnglish Ip,t,k/and/b,d,g/can sometimes be separatedby all three to contrastireexperience that Japanese have with Id/versusflapped Irl. measures,and these are thenacoustico-articulatory properties of the voic- (WhileEnglish does contain a flappedIrl, it isnot contrasted with/d/.) This ingfeature. But VOT alsoseparates subphonemic (allophonic) variants of researchfurther compared English and Japanese speakers' ability to dis- /p,t,k/aspirated[ph,t h, k h] and unaspirated [p,t,k], and it iscustomary to tinguishthe Hindi contrastby providinglaboratory training and generali- regardthis differenceas phonologlcaltyirrelevant. Furthermore, CD cues zationtests for both languagegroups. Twenty native speakers from each voicingstate only when accompanied by a voicinggap, when a shortVGD is effectively(perceptually?) equivalent to one of zero duration,so the unaspirated,voiceless-aspirated, and voiceless-unaspirated dental and ret- voicinggap may be "dismissed"as a consequenceof pressure equalization roflexconsonant-vowel syllables produced by 2 nativeHindi speakersin 3 ratherthan a linguisticallymotivated laryngeal maneuver. Elsewhere the vowel contexts(/a/, /e/, /o/). Trainingconsisted of 12, 30-min sessionsin value of CD is more prosodic(morale) than segment-identifying,distin- which only voiced-aspiratedtokens produced by 6 Hindi speakersin 2 3417 J. Acoust.Sec. Am., Vol. 97, No. 5, Pt. 2, May 1995 languagegroup1291hwereMeeting: pretestedAcoustical andpost-testedSociety onvoiced-aspirated,of America voiced- 3417 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp vowel contexts(/a/ and /o/) were presentedin a self-paced,self-selected Each syllablewas repeated3 timesby eachspeaker. The vowel in the fashion.While Japanesespeakers performed at muchhigher levels than syllablewas [i,a,u] and the consonantwas [r] or [1] in geminatedand Englishspeakers, both groups improved markedly and showed generali- nongeminatedform, leading to 216 syllables.Confirming the resultsof a zation to new speakers,new vowel contexts,and new voicing/manner previousstudy on Italian stop consonants [R. Rossetti,J. Acoust. Soc. Am. contexts.[Work supportedby NIDCD andApplied Telecommunications 95, 2874 I1994)]results of thepresent analysis showed that the first vowel Research,Kyoto, Japan.] durationwas systematicallyshortened in the geminatedconsonants. The data also showedthat in the presentcase the durationof the consonantas 5pSC9. Visual feedbacktraining for a nasal/non-nasaldistinction. well as,in mostcases, of the VC andCV transitionswere lengthened in the Anna Marie Schmidt (SchoolOf SpeechPathol. & Audiol., Kent State geminatedform. Spectral analysis showed that there is littleor noeffect on Univ., P.O. Box 5190, Kent, OH 44242) thespectral properties of theconsonants due to thepresence of gemination. Nativespeakers of someChinese dialects do not makea distinction However.[r] in geminatedform is in a few casesdevoiced. Informal between/n/and/1/.This lack of a phonemicdistinction may be a problem perceptualtests indicate that [r] canbe automaticallygenerated from [1] by whenthese speakers learn English and the distinctionis oftendifficult to introducinga silent portion within the stationary portion of [1]. teach.Three native Chinese speakers from Shanghaiwho hadbeen in the 5pSC13. A connection between coarticulafion and variable rule US lessthan 2 yearsparticipated in a trainingexperiment using a nasom- application:Coda r's in BrooklynEnglish. Kennethde Jong (Dept.of eterto providevisual feedback. Production was trained in initialposition in Linguistics,322 Memorial Hall, Indiana Univ., Bloomington,IN 47403) minimal pairsusing initial/n/-/1/and/sn/-/sl/pairs. Subjects'perception and ElizabethC. Zsiga (GeorgetownUniv., Washington,DC 20057) of the distinctionin Englishminimal pairs was tested prior to trainingand post-trainingusing both same/different andcategorization tasks. Ohala (1975, 1981) has proposedthat soundchanges are causedby listenersmispereeiving coarticulatory effects. This paperexamines van- 5pSCI0. Effects of perceptual learning on the production of a able "r-dropping"in BrooklynEnglish. and discussesthe coarticulatory non-nativecontrast. ReikoA. Yamada,Yoh'ichi Tohkura (ATR Human exigenciesthat may encouragespeakers toward weakenedforms. It is Info. Process.Res. LabS., 2-2, Hikaridai, Seika, Soraku, Kyoto, 619-02, arguedthat productionstrategies do play a role in driving soundchange Japan), Ann R. Bradlow, and David B. Pisoni (Indiana Univ., apartfrom creatingmisperceptions. Recordings were madeof speakersof Bloomington,IN 47408) Brooklynand other dialectsas part of the developmentof a larger multi- Previousresearch has showna significantcorrelation between the per- dialectdatabase (Hertz et al., 1994).Analyses of nuclearr's (asin bird,and ceptionand production of English/r/and/l/byJapanese speakers [Yamada burll showthat neighboringl's both lower the secondformant and raise the et al., Proc.ICSLP94, 2023-2026 (1994)].The presentstudy further in- thirdformant. obscuring the r. Analysesof codar's in "r-ful" speakersalso vestigatedthis perception-productionlink by examiningthe transferof show following coronalsraise the r's third formant. Analyses of three trainingin perceptionto productionof a non-nativeContrast. Twelve Brooklyn speakersshow one consistentlyproduces coda r's, one never monolingualJapanese speakers were trainedto perceivethe English/r/-•/ does,and a third doesso variablyas evidentin a bimodaldistribution of contrastusing a high-variabilitytraining program [Lively et al., J. Acoust. formantpatterns. The variablespeaker produced r-less tokens particularly Soc.Am. 96, 2076-208711Recordings were also made of the trainees' in codaswhich contained coronals, especially 1. This patternsuggests that productionsof Englishlff-/l/minimal pairsbefore and after the perceptual coarticulatoryinfluences affect the application of variablerules. Thus coar- training.These pretest and post:testrecordings were then evaluatedper- ticulationseems to exertpressure within a speakertoward a changedform. ceptuallyby Americanlisteners who werepresented with pairsof tokensin [Worksupported by the NIDCD.] anA-B testformat. As expected,subjects' accuracy on theperceptual task 5pSC14. Time-variation in Mandarin voicelesssibilant spectra. Yi improvedby about16% after 45 trainingsessions. More importantly,sub- Xu (Res.Lab. of Electron.,Rm 36-513. MIT Cambridge,MA 02139) jects'productions at pretestand at post-testwere distinguishable by Ameri- canlisteners. More post-testproductions were judged as "better" tokensof The threeMandarin sibilant fricatives. [s], [•], and[g], werestudied English/r/and/1/than pretestProductions. Implications for the pereeption- using a combinationof ume averagingand ensembleaveraging as de- productionlink in the acquisitionof novel phoneticcontrasts Will be dis- scribedby Xu andWilde [J.Acoust. Soc. Am. 96, 3230(A) (1994)].Ten cussed.[Work supported by NIH andATR.] nativespeakers of BeijingMandarin (5 maleand 5 female)produced these 5pSCll. An articulatory and perceptual study of Tamil liquids. fricativesfollowed by both unroundedand roundedhigh vowels.Time- JoyceMcDonough and Keith Johnson (Dept. of Linguistics•Ohio State averagedspectra were obtainedby averaging13 consecunve8-ms FFr Univ., 222 Oxley Hall, 1712 Nell Ave., Columbus,OH 43210-1298) windows over 20-ms intervals.Token-ensemble-averaged spectra were then obtainedby averagingover the time-averagedspectra of 10 repeti- In Tamil there are 5 liquid consonants.They are the lateral approxi- tionsof eachsentence produced by eachspeaker at time-normalizedloca- mation[1], the retroflexlateral approximant [0, the alveolartap [r], the tionsin the utterances.Further ensemble-averaging was also performed retroflextap [[], andan obscure segment that has been variously described. bver the male and female speakersseparately to obtain group-ensemble- This paper presentselectropalatography data from one speakerand per- averaged spectra. Preliminary examination of both token-ensemble- ceptualdata from five listenersexploring the articulatoryand acoustic averagedand group-ensemble-averagedspectra reveals that (a) Mandarin dimensionsof the phoneticspace for liquidsin Tamil. The dimensions sibilantshave substantialtime variationin their noisespectra, indicating whichare exploredinclude duration (distinguishing flaps and approxi- continuousart•culatory movement throughout the production of the frica- mants),dynamic tongue movement (distinguishing retroflex and nonretro- tion:and (b) all threesibilants manifest substantial spectral variation due to flex),and constriction location/spectral shape (distinguishing [1]and the anticipatorycoarticulation with thefollowing vowel. This kind of variation obscureliquid). Preliminary analyses suggest that the obscure liquid of is evidentfrom the very beginning of thefrication noise, indicating that the Tamil is an apleopalatalcentral approximant.[-[owever, unlike other seg ,xtant of th, anticipatoryeoartieulation may go bayandtha haginningof mentsin Tamilwhich require tongue tip backing(the retroflexes) there is the frication.[Work supported by NIH.] no evidenceof dynamictongue movement during the closureand some 5pSC15. Individual differences in the glottallzation of vowel-initial suggestionof acousticzeros, perhaps from a lateral opening.Additional syllables. Laura Dilley and Stefanie Shattuck-Hufnagel (Speech perceptiondata designedto clarify this picture will 'be presented. Conunun.Group, Res. Lab. of Electron.,MIT, Cambridge,MA 02139) 5pSC12.Acoustic analysis of Italian [r] and [1]. Francesca.Argiolas, FedericoMacd, andMaria-Gabriella Di Benedetto(Dept. INFOCOM, Speakersof American English often glottalize the onset of a vowel- ,Universithdegli Studi di Roma'La Sapienza',via Eudossiana18, 00184 initialsy,,lla•ale, andrecent work has shown that this is particularly likely to Rome,Italy) . occurwhen the syllableis locatedat prosodicallysignificant locations, suchas the beginningof an intonationalphrase, or at a pitchaccent [Pier- Acousticanalysis of Italian[r] and[1] wascamed out. Speech mate- rehumbertand Talkin Labphon II, 1992:Dilley et al., J. Acoust.Soc. Am. rials consistingof prestressedVCV syllablesproduced by 3 male and 3 95, 2978(A) (1994)].Analysis of speechread by 4 differentprofessional female native speakersof Italian formedthe basisof the presentstudy. radionews announcers and4 nonprofessionalspeakers shows (ai theim- 3418 d. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: AcoUStical Society of America 3418 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp portartecof prosodicstructure in determiningthe occurrence of glottaliza- abouteach token: i. What word is the speakersaying? and, it. Doesshe lionholds across speakers, (b) speakersare differentially likely to glottai- speakthe samedialect you do?Their judgments were generally consistent ize overall,and (c} speakersare differentiallylikely to glottalizein with the discriminantanalysis classifications. differentprosodic contexts. For example,the 4 FM radio newscasters showedoverall glottalization rates of 41%, 38%, 22%, and 7%, and some 5pSC19. Perceptual assimilation of North German vowels to speakerswere more likely to glottalizereduced vowels than others were. American English categories. Sonja A. Trent, Brett H. Fitzgerald, The implicationsof thesepatterns of variationfor speechrecognition and SusanM. Crouse,and WinifredStrange (Dept. of Commun.Sci. & synthesis,as well as for modelsof speechproduction planning, will be Disord.and Psycbol., Univ. of SouthFlorida, 4202 E. FowlerAve., Tampa, FL 33620-8150) discussed.[Supported in partby a grantfrom NIDCD.] 5pSC16, Articulatory modeling of so-calledadvanced tongue root Perceptualassimilation of NG vowelsto AE categorieswas assessed vowels. ScanFulop, Ethelbert Karl, and PeterLadefoged (Phon.Lab., with stimuliin which the vowelsoccurred in/hVp/syllables spokenin LinguisticsDept., UCLA, Los Angeles,CA 90024-1543} citationform and in thesentence, "Ich habe/hVp/gesacht."Subjects were presentedmultiple tokens of 14 NG vowelsproduced by 4 male talkers. Many WestAfrican languages have two setsof vowelsthat are saidto They selectedthe AE vowel categoryto which the NG vowel was most differby onehaving an advancedtongue root [+ATR], andthe other a similarand rated its goodness-of-fit on a 7-pointscale from "English" (7) retractedtongue root [-ATR]. The[+ATR] setmay also have an enlarged to "foreign-sounding"(1). "Identical"vowels (transcribed as the same pharynxand a loweredlarynx. Words (roots) in theselanguages must acrosslanguages) did notnecessarily assimilate to thepredicted category. contain vowels that are all of one set or the other. To test whether there is "New" front reundedvowels ly, Y, O, oe/assimilatedto back roundedAE a constantacticulatory difference between the two setsof vowelsin De- vowels.Perceptual goodness-of-fit was not alwayspredicted from the pho- gema, a Delta Edoid languagespoken in Nigeria, DAT recordingswere neticdescription or acousticsimilarity in FIIF2 spacelB. H. Fitzgerald madeof 8 speakers.For 2 of the speakers.frontal and lateral videos were eta/., J. Acoust.Soc. Am., thissession]. Differences in modalidentifica- madeof the lip aperture.The frequencies,amplitudes and bandwidthsof tion responseand goodness-of-fitwere notedacross citation versus sen- the first 3 formantsof the 5 pairsof vowelswere determinedfrom LPC tencecontext and acrossindividual speakers. Assimilation on the basisof analysis.These data were modeled using an articulatorysynthesizer. After intrinsicduration information was moreconsistent for syllablespresented an appropriateset of vocal tract shapeshad been determinedfor the in sentences.These results have implications for studiesof cross-language [-ATR] setof 5 vowels,articulatory perturbations such as tongueroot similaritywhich use citation-form stimuli. [Work supported by NIDCD.] advancement,pharynx enlargement, and larynx lowering,were appliedto 5pSC20.Acoustic specification of North German vowelsproduced in the modeled[--ATR] vocalIract shapes to generatethe [+ATR] set.A citation and sentencecontexts. Brett H. Fitzgerald,Sonja A. Trent, varietyof articulatorygestures seem to be neededto convertvowels from JanetW. Stack,Xiange Ling, andWinifred Strange (Dept.of Commun. one set into the other. Sci. & Disord.and Psychol.,Univ. of SouthFlorida, 4202 E. FowlerAve., 5pSC17. Perception of vowel length in Arabic. Abdulla A. AI-Ba- Tampa,FL 33620-8! 50) nnaia) (Dept.of EnglishLanguage and Literature, United Arab Emirates Univ., P.O.Box 671612,Al-Ain, U.A.E.) As partof a largerstudy of Iheeffects of speechstyle and consonantal contexton the acousticspecification and cross-languageperceptual simi- This studyinvestigates the acousticcorrelates of distinctivevowel larityof vowels,this study examined differences in acousticparameters of lengthin Arabic,and examines the extentto whichthese cues might figure NorthGerman (NG} vowelsin hVpsyllables produced in citation-form(as in the phonologicaldistinction of vowel lengthin Arabic.The perceptual lists)and in the carriersentence "Ich habe--gesacht."Two instancesof experimentdetermines the accuracywith whichvowel duration contrast in eachof 14 vowelsproduced by 4 malespeakers (Kiel dialect)spoken in spokenArabic can be auditorilyrepresented. The methodwas to createsets eachcontext were analyzed. Vowel formant frequencies (measured at syl- of stimuliby addingor removinga variablenumbers of the excisedvowel lablemidpoint) showed some undershoot of FI in sentencecontext rela- pitchperiod in the dataselected. These stimuli were presentedto native tive to citation context; F2 undershootwas minimal. Duration differences speakersof Arabicin a wordidentification task. The perceptualaccuracy of belwennspectrally similar tense-lax pairs variedas a funeltonof vowel vowel durationas determinedfrom the slopesof the identificationcurves heightin both citationand sentencecontexts. Overall, tense-laxduration revealed that relative vowel duration is the dominant acoustic cue in the differences were reduced in sentence context relative to citation form. phonologicaldistinction of vowellength in Arabic.But spectralcues such Individualdifferences across speakers in bothFIIF2 targetsand intrinsic assteady-state formant frequency, level of intensityplay a significantsec- durationswere noted.Distances in FIIF2 spacecould not accountfor ondaryrole in the discriminationof vowel contrastwhen the relativedu- perceptualassimilation patterns of AE listeners[see S. Trentet aL, J. rationis maximallyambiguous between short versus long vowels. a)Send Acoust.So{;. Am., this session]. These results have implications for con- noticeto: P.O.Box 5837, Sharjah,U.A.E. ceptionsof phoneticprototypes used to accountfor cross-languagesimi- larity.[Research supported by NIDCD.] 5pSC18. The relation between dialect attribution and vowel judgments, Alice Faber (HaskinsLabs., 270 CrownSt., New Haven, 5pSC21. Acoustic correlates of Deg Xinag/Ingalik Athabaskan CT 06511), Lawrence Brancazio (Univ. of Connecticutand Haskins vowels. Alice Taff (Dept.of Linguistics,Univ. of Washingtun,GN-40, Labs.),and CatherineT. Best (WesleyanUniv. and Haskins Labs.) Seattle,WA 98195) A spokenword's phonetic form providesinformation not only about Therehas been controversy [A. Jerueet al., Deg XinagDindlidik. the speaker'sintended message but also about the speaker'slanguage ANLC: Fairbanks( 1993)] over the classification of thevowel in thesecond and/ordialect background. The form[dak] may reflect southern U.S. dike, personplural morpheme (2p) in Deg Xinag/Ingalikas eitherIo/or Iol. Bostondark, or Chicagodock. Someone who makesan incorrectdialect Acousticmeasurements were undertakentowards resolving the issue.F I, attributionmay misinterpret statements about the [dak]. Anecdotal reports F2, F3, and ruralion were measuredfor each of the five vowels in the of suchmisunderstandings abound (e.g., Labov, 1994). In anexperimental system,/a,e,o,o,o/.Contexts were limited to coronaland uvular. FI and investigation,it wasassessed whether listeners' labeling of isolatedwords F2 meansfor datafrom two speakersindicate that 2p is morelike/o/than is systematicallyinfluenced by correctversus incorrect attribution of /oL Vowellength data supports this claim. speakerdialect. Words thai are incorrectlyassigned to their own dialect 5pSC22. Waveform dynamicsand the perceptual segregationof shouldbe mislabeled,in ways predictablefrom the relativepositions of concurrent vowels, Peter Assmann (School of Human Develop.. Univ. vowel nuclei in the vowel spacesof the two dialects.Stimuli were tokens of Texas, Box 830688, GR 41, Richardson,TX 75083) of heed, hayed, head, hood, hoed, HUD, producedby Utah and Connecticutwomen. Discriminant analyses trained on theConnecticut pro- Whentwo syntheticvowels are presentedconcurrently, listeners iden- ductionscorrectly classified Utah heed, hayed, andhead; Utah hoed was tify the vowelsmore accurately if they differ in fundamentalfrequency often classifiedas Connecticuthood, and Utah hood and HUD were clas- (F0) or if oneof themis preceded/followedby a gliding(versus static) siftedas Connecticuthead. Connection listeners answered two questions formantpattern. Previous experiments have shown that gliding formants 3419 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3419 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp generallydo not help listeners identify the vowel to whichthey are linked; theoryis contradictedby themagnet effect [P. Kuhl, Pemept. Psychophys. instead,they makethe vowel withouttransitions easier to identify.One 50, 93-107 (1991)]which indicates that some areas of thevowel space are explanationis thatthe formanttransition region provides a brief interval perceptuallyshrunken. Experiments with naive adult subjectswere ex- during which the competingsteady-state vowel is perceptuallymore ecuted.Generalization, ABX, and discriminationexperiments were per- prominent.This interpretationis supportedby two computationalmodels formedusing eight cardinalvowels plus intermediatesteps between se- thatperform a filter bankanalysis, process the waveformin eachfilter lected vowels. Results,indicating both Shepardand Kuhl are partially channelusing a slidingtemporal window, and determine which region of correct,are bestrepresented by Gluck'sscheme [Psych. Sci. 2, 50-55 the signalprovides the strongestevidence of eachvowel. Model A com- (1991)]with the data indicating that it is thedistinctive features of vowels putedthe energyin eachchannel at successivetime intervalsto generate that are perceivedcategorically. There was little evidenceof language- runningexcitation patterns. Model B useda temporalanalysis to generate specificeffects for adults.Pilot work with newbornsindicate that they runningautocorrelation functions, and includeda furtherstage to partition organizethe vowel spacelike adults. the channelsbased on periodicitycues. Both modelspredicted effects of 5pSC26. Psychophysical procedure and the perceptual magnet F o and glidingformants, but modelB providedbetter predictions of the effect: Comparisons of fixed and roving AX discrimination of /iL patternof listeners'identification responses. Identification of concurrent Paul Iversonand PatriciaK. Kuhl (Dept. of Speechand Hear. Sci., vowelsappears to benefitfrom an analysisof the compositewaveform WJ-10, Univ.of Washington,Seattle, WA 98195) usinga slidingtemporal window, combined with a form of F0-guided sourcesegregation. Recentexperiments by Iversonand Kuhl [J. Acoust.Soc. Am. 97, 5pSC23.About the fourthangle of the "voweltriangle." Rent Cart6 553-562 (1995)]have demonstrated that the perception of/i/is influenced (ENST., 46 rue Barfault,Paris, France) by categorygoodness. Listeners exhibit a perceptualmagnet effect char- acterizedby highsensitivity to acousticdifferences near poor exemplars of The voweltriangle can be derivedfrom the acoustic theory JR. Cart6 /i/and low sensitivitynear excellentexemplars of/i/. The presentstudy et al., J. Acoust.Soc. Am. 95, 2924 (A) (1994)].The areafunction was examineswhether this effectis influencedby psychophysicalprocedures. deformedin orderto increaseor decreaseF1 or F2. In this new study,the Listenerswere askedto discriminatepairs of stimuli from an /i/ to /e/ acousticcriterion is to increase(or decrease)both F1 andF2 or to increase continuum,and the taskwas variedin two ways:(1) Eachblock of trials F1 (or F2) and decreaseF2 (or F1). At the end of the deformation hadeither one pair of tokens(fixed discrimination) or parisof tokensfrom process,the area functions produce the most "compact" (F1 andF2 close the entire stimulusrange (roving discrimination), and (2) the acoustic as in/a/) or "diffuse"(F1 far fromF2 as in/i/) or "grave"(FI andF2 differencebetween each pair of tokenswas either 30 or 60 mels. The bothlow as in/u/) sounds.But whatabout an "acute"vowel (FI andF2 resultsdemonstrated that the peakin discriminationat the/i/-/e/boundary bothhigh) which could correspond to thefourth angle? It canbe automati- diminished with fixed discrimination tasks and 30-mel differences between cally convergedto a patternwhere F1 is aroundat 1000 Hz and F2 at tokens,supporting previous findings [Macmillan et al., J.Acoust. Soc. Am. 2000 Hz. But in this case the ratio between the maximum value of the 84, 1262-1280(1988)]. However, the magnitude of theperceptual magnet cross-sectionalarea divided by the minimum value becomesaround 80. effect seemedless influenced by thesemanipulations. The resultssuggest Thisratio is only20 (between0.5 and10 cm 2) forthe "compact" versus that distortionsof sensitivityat boundariesand within phoneticcategories "diffuse"axis (from/a/to/i/). Thusreaching this fourth angle is toomuch may arise from different mental processes. costlyin deformationamplitude and thuspoorly efficient. 5pSC27. An investigationof the perceptual magnet effect in adults. 5pSC24.Does the perceptualmagnet effect hold for the [•] category? SusanC. Renda,John W. Hawks,and RichardKlich (Schoolof Speech JoanE. Sussman(Dept. of Commun.Disord. and Sci., State Univ. of New Pathol. and Audiol., Kent State Univ., Kent, OH 44242) York at Buffalo, 122 Park Hall, Buffalo, NY 14260) and Brian S. Gekas (SUNY at Buffalo, Buffalo, NY 14260) Three experimentswere undertakento investigatethe validity and strengthof the pemeptualmagnet effect in adults.First, the originalper- Recentspeech perception investigations [J. E. Sussmanand V. J. ceptualmagnet experiment [P. K. Kuhl,Percept. Psychophys. 50, 93-107 Lauckner-Morano,J. Acoust.Soc. Am. 97, 539-562 (1995); P. Iversonand (1991)]was directly replicated with adults, using Kuhl's stimulus param- P.K. Kuhl,J. Acoust. Soc. Am. 97, 563-572 (1995)]support a "perceptual eters.These subjects were then tested with theAAXX protocolused to test magneteffect" [P. K. Kuhl,Percept. Psychophys. 50, 93-107 (1991)],i.e., monkeysin Kuhl (1991). Generalizationscores were computed for sub- poordiscrimination around a bestexemplar compared with discrimination jects under both conditionsand compared.A secondgroup of subjects arounda poorexample of thecategory. To date,the magnet effect has been rateda largenumber of/KY/vowel tokensin thenext experiment. Average observedusing the vowel[i] or consonantcategories. A magneteffect ratingswere computed and a prototype(P) andnonprototype (NP) were mightbe expectedbecause a rangeof good[i] tokensaround a "best" chosenbased on them. Variantsof each were synthesizedas in Kuhl exemplarwould exist. However, a magneteffect may not occurfor vowels (1991).Subjects rated the goodness of eachvariant on a scalefrom 1 to 7. with smallerand more variable categories. Each of 10 listenersrated [ib] In additionthey assigned a 0 to anytoken perceived as not belonging to the stimulias the [i] in "bib" or not the [i] in "bib." Then,each listener heard /i/ category.The subjectsthen participated in the perceptualmagnet ex- the tokenshe/she had labeledas [•] at least50% of the time and chosea periment.Data from trials containingstimuli assigned0 were excluded "best[x]." Results show that [•] hasa smallerrange (45-60 reels)around from analysis.In the third experiment,a large numberof/EH/ vowel a bestexemplar than [i]. Subjectschose different tokens as their "best" tokenswere ratedand P and NP were chosen.Variants were synthesized exemplarand varied in thenumber of tokenslocated in their[•] categories. and rated and the perceptualmagnet effect experimentwas again con- Finally, resultswere comparedto two sessionsof a Change/No-change ductedusing these tokens. Results and implicationsof theseexperiments discriminationtask: One with the "best[•]" s the fixedstandard, the other will be discussed. with a poorer example of [l] as the fixed standardfor measurementof a magneteffect. SpSC28. Production of highly similar vowels by language-impaired children. JuneStealy, Rachel E. Stark (Dept. of Audiol.and Speech 5pSC25. Generalization in the vowel space. Michelle Aldridge Sci., PurdueUniv., West Lafayette,IN 47907), and John M. Heinz (Cailler Ctr. for Commun. Disord., Univ. of Texas, 1966 Inwood Rd., (Kennedy-KriegerInst., Baltimore, MD 21202) Dallas, TX 75235) It hasbeen shown that languageimpaired (LI) childrenhave greater Vowelsmay be representedby a three-dimensionalvolume of space. difficultythan language normal (LN) childrenin identifyingthe synthe- The axesof the volumemay be definedin articulatoryterms (front-back, sizedvowels/•/vs/ce/, but not/o/vs/i/, whenthe membersof testpairs high-low,rounded-uurounded) or in physicalterms (F1, F2, F3). Shep- are of equalduration (240 to 40 ms) [R. E. Stark and J. M. Heinz, J. ard[Science 237, 1317- 1323(1987)] plotted data of Petersonand Barney Acoust.Soc. Am. 91, 2360 (A) (1992)]. It was concludedthat, when [J. Acoust.Soc. Am. 24, 175-184 (1952)]to showthat generalization in deprivedof thedurational cues present in naturalspeech, LI childrenwere the vowel spaceis an instanceof his universallaw of generalization,an lesswell able than LN to rely upon subtlespectral cues. In the present exponentialdecay function with physical measureson the x axis. This study,children in both groups(11 LI, 9 LN) were askedto imitate the 3420 J, Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3420 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp synthesizedvowels Iœ1 and loci. Their responses were recorded, tran- vowel informationin the breathsalso favored one end of the continuumor scribed,and submitted to spectralanalysis. Responses of individual chil- theother. Two resultssuggest that, under some circumstances, vowel iden- drenthat were given to either/e/or Ice/werescored as correct, those that tificationwas affected by breathprecursors: (1) Therewere morePJ re- weregiven to bothvowels indiscriminately were not. The scores of thetwo spouseson the "bid-bed"continuum following the femalebreaths; (2) groupswere not significantlydifferent. However, the LI children'sre- therewere more/•e/responses following the maleand female a•-breath. spouseswere transcribed as morevariable, and occupied a greaterrange Paradoxically,natural speech precursors shifted identification toward the withinF• - F z plots,than those of theLN children.The results support the oppositegender's formant space. Another test suggests that these vowels hypothesisthat LI childrenhave "fuzzy" phonological categories. [Work identificationshifts did notarise postperceptually. supportedby NIH.] 5pSC32. Intersyllabicregulation of F0 and SPL with and without 5pSC29.Timing effectsof postvocalicvoicing and distinctivevowel auditory feedback, Jane Wozniak, Harlan Lane, Joyce Manzella, length. Dawn M. Behne,Bente Moxness (Univ. of Trondheim,7055 JosephPerkell, Melanie Matthies,Mario Svirsky,Michael O'Coonefl, Dragroll,Norway). and PeterE. Czigler (Ume• Univ.,901 87 Ume•, andClay Mitchell (Res.Lab. of Electron.,Rm. 36-51 I, MIT, Cambridge, Sweden) MA 02 i 39) Syllable-internaltiming can be affectedby a varietyof factors,includ- Syllable-to-syllablefluctuation of F0 and SPL were measuredin read- ing postvocalicvoicing and distinctivevowel length.Both factorshave ingsof a passageby 4 post-linguallydeafened adults, recorded before and beenfound to inverselyaffect vowel duration and the duration of a postvo- after they received cochleat implants, and one adult with calic consonant,resulting in similarrhyme-internal timing patterns.Is neurofibromatosis-2(NF2), who wasinitially profoundly deaf in oneear thereany indicationthat syllable-intcrnaltiming uniquely characterizes andhad a mild to moderateheating loss in the other(aided). Three of the distinctivevowel length and postvocalic voicing? Three experiments have 4 cochlearimplant users reliably reduced syllable-to-syllable fluctuation in beencarded out investigatingcombinations of postvocalicvoicing and F0 andSPL following the activation of theirspeech processors. The fourth distinctivevowel lengthin English,Norwegian, and Swedish.For each speakerbegan with and maintainedthe regularityachieved by the others languagea controlledset of CVCs wasselected in whichthe finalconso- post-activation.In recordingsmade following the onsetof bilateralpro- nancswere either voiced or voiceless.In addition,Norwegian and Swedish found deafness,the NF2 subjectshowed increased syllable-to-syflable CVCs wereselected which had distinctively short or longvowels, and for fluctuationin F0 andSPL. Results from another experiment [M. A. Svir- English,words were chosen which contained inherently short and long skyeta!., $. Acoust.Soc. Am. 92, 1284-13000992)], in whichmultiple vowels.The targetitems were recordedin carriersentences and durations repetitionsof vowelsin an/hVd/context wereproduced by cochlearim- of the initial consonant,the vowel, and final consonantswere measured. plant userswith their processorsturned off and on, suggestthat some Resultsdemonstrated the expectedinverse timing relationswithin the subjectsshowed less token-to-token variability in F0 and SPL with their rhymeassociated with postvocalicvoicing and distinctive vowel length. In processorsturned on. The presentresults indicate that auditoryfeedback addition,prevocalic consonant duration was consistently distinct for con- may alsoconstrain the syllable-to-syllablevariability of F0 and SPL con- ditionsof postvocalicvoicing compared to distinctivevowel length. Find- tours.[Work supported by NIDCD.] ingsfor English,Norwegian, and Swedishwill be discussedin termsof 5pSC33. A qualitative study of mechanisms of jitter-induced syllable-internaltiming. shimmerin the voice. DarrellWong (WJ GouldVoice Res. Ctr., Denver 5pSC30.Laxness of voice quality integrateswith FI (usually,but Ctr. for the PerformingArts, 1245 ChampaSt., Denver, CO 80204), not always,negatively). LauraWalsh, Christine Bartels, John Kingston RobertLange (WJ Gould Voice Res. Ctr.), lngo R. Titze (Univ. of (LinguisticsDept., Univ. of Massachusetts,Amherst, MA 01003), and Iowa), and ChwenGeng Guo (WJ GouldVoice Res. Cu'.) Nell A. Macmillan (BrooklynCollege, Brooklyn, NY 11210) Measurementsof jitter and shimmerare typicallyapplied to micro- Bothlax voiceand advanced tongue root typically concentrate energy phonesignals to discernthe level of perturbationsin the oscillatorybe- at low frequencies:Laxtug the voice increasesthe relativeprominence of haytotof the vocalfolds. Shimmer, the averagecycle-to-cycle change in the firstharmonic, and advancing the tongueroot lowers Fl. A previous amplitude,is knownto linearlyincrease as theextent of amplitudemodu- study[Thorburn et eL, J.Acoust. Soc. Am. 95, 2871(A) (1994)]using the lationof tissuedisplacement increases. Behavior under frequency modu- Garnerparadigm found that theseacoustically similar effects integrated lation(FM), however,is nonlinear.This nonlinearityis oftenattributed to perceptuallyfor vowelsin CVC context.In thisstudy, the rangeof voice timealiasing, the superposition ofjittered impulse responses (assuming the quality was extendedto include tensor values.Across the entire set of source-filtermodel of phonafion).As a consequence,whenever jitter is voicequalities sampled in the two experiments,laxness integrated nega- present,any measurementof shimmercannot be solelyattributed to am- tivelywith FI at thelax andtense ends of thecontinuum but positively at plitudemodulation of the vocalfold tissue.The presentstudy attempts to intermediatevalues. This patternof mean integralilyis distinctfrom the characterizeother sourcesof FM-induced shimmerby examiningpoints additionalfinding of varianceintegral#y, that is, greateruncertainty in earlier in the voiceproduction process. An interactivecomputer simulation judgingvoice quality when FI variedIhan when it did not(and similarly of the vocal fold and vocal tract systemis used under conditionsof FM for judgmentsof FI). Accordingto a modelof Durlachet aL [Percept. « subharmonicmodulation ofthe tissue displacement. It appears that, in Psychophys.46, 293-296 (1989)], the variance-integralityeffects can be additionto time aliasing,shimmer may be generatedfrom FM-induced attributedto a sensoryrather than a context-codingsource. [Work sup- perturbationsin mucosalwave propagationand tissuedisplacement. The poredby NSF andNIH.] paperqualitatively describes and illustratesthese jitter-induced shimmer mechanisms. 5pSC31, Perceptual normalization of synthesizedvowels following natural speechand breath sounds. Sonya M. Sheffertand D. H. 5pSC34. Exit jet part'de velocity in the in vivo canine laryngeal Whalen (HaskinsLabs., 270 Crown St., New Haven, CT 0651I} model. Steven Bielamowicz, Gerald S. Berke, Jody Kreiman, and BruceR. Gerratt (UCLA Div. of Headand Neck Surgery, UCLA School The identificationof syntheticvowels relies in part on a precursor of Medicine,CHS 62-132, Los Angeles,CA 90024) phrase,suggesting that normalization is takingplace. Breath intake sounds, which can also precedespeech, may also give information.This study This studyextends the previouswork on exit jet particlevelocity in an examinesboth speechand breathprecursors. Two adult speakers(one in vivocanine laryngeal model of phonation[G. S. Berkeet el., J. Voice3, male, one female)produced the phrase"The next one is." They also 306-313 (1989)].In boththe previous and the currentstudy, a hot-wire producedaudible breath sountis before saying the words "bead," "bad," or anemometerwas used to measureair particlevelocity in the midlineof the "bud." Two 5-member continua were created, one from "bid" to "bed," glottisat anterior,intermediate, and posterior positions. Simultaneous mea- anotherfrom "bad" to "bud," basedon thesewords produced by each surementsof subglottalpressure, EGG, and PGG were alsoobtained. In speaker.FormanIs were averages (across the two speakers) for thenatural the previousstudy, these measures were obtained with constantlevels of productions;F0 was 160,resulting in genderneutral tokens. The genderof recurrentlaryngeal nerve (RLN) and superior!aryngeal nerve (SLN) precursorspeech and breathbefore each continuum item were varied.The stimulation.In the current study,exit jet particle velocity profiles were 3421 d. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129th Meeting:Acoustical Society of America 3421 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp obtainedacross multiple levels of RLN andSLN stimulation.Exit jet glottalconfiguration during pronation and the nature of theglottal pulse. particlevelocity was also measured at midlineand off-midline positions Subjectsfell intotwo groups based on the acoustic measurements, group 1, with constantlevels of RLN and SLN stimulation.The time-varyingfea- assumedto have abruptglottal closureand group2, assumedto have turesof exit jet particlevelocity as a functionof subglottalpressure and nonsimultaneousclosure. Results of a listeningtest have shownthat mem- glottalvibratory events will be presented. bersof group2 areperceived to bebreathier than members of groupI [H. 5pSC35. GIottal characteristicsof female speakers•acoustic, M. Hanson,Proc. ICASSP-95 (in press)].The currentstudy extends the physiological,and perceptualcorrelates. Helen M. Hanson(Div. of earlierwork in severalways. Physiological measurements have been made Appl. Sci., HarvardUniv., Cambridge,MA 02138 and Res. Lab. of for four subjects,including inversed filtered airflow recordings and glottal Electron.,ILm. 36-579, MIT, Cambridge,MA 02139) imagesobtained by fiberscopy.Also, listeningtests using synthesized speechhave been carried out to studythe role of glottalcharacteristics in A previousstudy of vowelsproduced by femalespeakers showed sub- stantialindividual differences in acousticparameters related to glottalchar- speakerdiscrimination, and the usefulnessof the acousticmeasures for acteristics[K. N. Stevensand H. M. Hanson,in VocalFold Physiology: guidingthe synthesisof naturalsounding speech. The physiologicaland VoiceQuality Control (Singular, San Diego, 1995)]. Based on measure- perceptualdata are found to beconsistent with theearlier interpretations of mentstaken on thespeech signal or spectrum,inferences were made about the acousticmeasures of glottalcharacteristics. SATURDAY AFTERNOON, 3 JUNE 1995 GRAND BALLROOM SOUTH, 1:00 TO 4:50 P.M. Session5pUW Underwater Acoustics:Target Scattering ChristopherFeuillade, Chair Naval ResearchLaboratory, Stennis Space Center, Mississippi 39529-5004 Chair's Introductionml:00 ContributedPapers 1:05 527-536 (1993)]to the discrete Fourier components of the transient signal, andassuming linear supersposition. The solutionof Zimmermanand Stem 5pUWl. Bistaticscattering of underwater soundfrom a poroussolid is an analyticalseries solution. Its accuracyis mainlydetermined by com- sphere: A comparison of theory and experiment. Marfin E. Pace, putationerrors and the convergence of theseries. The incidentpulse can be TheodoreW. L. Huskey, Steven R. Baker (Phys. Dept., Naval any combinationof Blot fast and low waves.The theoreticalresults for PostgraduateSchool, Monterey, CA 93943-5000), StevenG. Kargl certaincases are shown.They are alsocompared to experimentalmeasure- (Univ. of Washington,Seattle, WS 98105), and RaymondLim (Coastal ments.[Work supportedby Naval ResearchLaboratory, Stennis Space SystemsStation, Panama City, FL 32407-7001) Center.] Measurementswere made of the bistatic scatteringof underwater 1:35 soundfrom a porous solid sphere.Two sample sphereswere employed composedof bonded glassbeads of 100- and 500-micron nominal grain 5pUW3. Multiple scattering from submergedbodies with dissimilar diameter,respectively. The diameterof eachsphere was approximately6.8 acoustical properties. Part I. Local impedance models. Gabriella cm. The scatteringinto the rearwardhemisphere was measuredover the Turek (MarinePhys. Lab., ScrippsInst. of Oceanogr.,La Jolla,CA frequencyrange 13 to 150 kHz, correspondingto values of ka from ap- 92093-0238), PeterH. Rogers,and Aldo A. Ferri (GeorgiaInst. of proximately2 to 20. Over this frequencyrange the viscouspenetration Technol.,Atlanta, GA 30332-0405) depthvaries from approximately5.0 to 1.5 microns,so thatthe waterin the A numericalsolution for a two-bodyacoustical multiple scattering porescan move freely.The experimentalresults were comparedto numeri- problembased on the analyticalinfinite series solution of the waveequa- cal computationsbased on a theoreticalBlot model[S. G. Kargland R. tion wasdeveloped. FORTRAN 77 codesimplementing this solution were Lira,J. Acoust. Soc. Am. 94, 1527-1550(1993)]. The physical parameters writtenwhich are capable of simulatingthe case of two spheresof arbitrary requiredby the modelwere obtainedby independentmeasurements on the radiusand distinct material properties subject to an acousticplane wave of samplespheres and on similar cylindricalsamples. Reasonably good arbitraryincidence. Far-field solutions involving permutations of the two agreementwas foundbetween the experimentaland theoreticalresults for "degenerate"boundary conditions (pressure release and rigid) werecom- the 100-micronsphere, especially at the lower frequencies,except for a paredto solutionsobtained with the combined Helmholtz integral equation consistentdeficit in the measuredbackscatter. Agreement between the re- formulationproblem (CHIEF) program.Surface prcaaurca and velocitlea sultsfor the 500-micronsphere was poor, probablydue to sampleinho- werealso calculated. [Work supported by ONR.] mogeneity. 1:50 1:20 5pUW4. Multiple scattering from submergedbodies with dissimilar 5pUW2. Scattering of a transient plane compression wave by a acousticalproperties. Part II. Experimental results. GabriellaTurek spherical inclusion in a Blot medium. Hans Schantz, Morris Stem, (MarinePhys. Lab., Scripps Inst. of Oceanogr.,La Jolla,CA 92093-0238), andJustin Beres (Appl.Res. Lab., Univ. of Texas,P.O. Box 8029,Austin, PeterH. Rogers,Aldo A. Ferri, and Gary W. Caille (GeorgiaInst. of TX 78713-8029) Technol.,Atlanta, GA 30332-0405) The scatteringof an arbitrarytransient plane wave by a sphericalin- In PartI [Tureket all a numericalsolution for a two-bodyacoustical clusionin a Blot mediumis modeled,by applyingthe singlefrequency, multiplescattering problem based on the analyticalinfinite series solution steady-statesolution of Zimmermanand Stem [J. Acoust.Soc. Am. 94, of the waveequation was presented. Surface and far-field solutions involv- 3422 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3422 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp ingpermutations of the two "degenerate"boundary conditions (pressure are confinedto the thermoclineregion of the watercolumn. The applica- releaseand rigid) werecompared to solutionsobtained with thecombined bility of classicswimbladder scattering models to describethese layers is Helmholtzintegral equation formulation problem (CHIEF) program.In presentedin additionto the spatialvariability observed in volumescatter thispaper the case in whichone of thespheres is fully elastic and the other fromdeep (Ionian' Sea) to shallow {Median Bank) ocean areas. pressurerelease is modeledand the results verified experimentally. 3:05 2:05 5pUWS. Predicted target strength analysis using computer 5pUWS. Modeling low frequencyscattering from small schoolsof techniques.Gerard P. Gay (Mech.Eng. Dept.,The CooperUnion, 51 fish. C. Feuillade,R. W. Nero, andR. H. Love (NavalRes. Lab., Stennis Astor Place, New York, NY 10003) and Daniel R. Raichel (City SpaceCenter, MS 39529-5004) Universityof New York) A low-frequencysecReting model for smallto moderatelysized fish Targetstrength was predicted for variousgeometric objects by a com- schoolshas beendeveloped. The modeluses a mathematicalformalism puterray tracingalgorithm. The ray tracingtheory assumes that the prop- basedupon the harmonic solution of setsof coupleddifferential equations, ertiesof soundat highfrequencies, entaillug wavelengths which are small and incorporatesa verified swimbladder scattering "kernel" for an indi- comparedwith the sizeof the targetobjects, are analogousto light prop- vidual fish.All ordersof multiplescattering interactions between the fish erties.This is a preliminaryexperiment still in progress.Four simpleob- are included,and the aggregatescattering field calculatedby coherent jects:Sphere, cylinder, cube, and disk, and two compoundobjects: Cylin- summation.Application Io ensemblesof closelyspaced fish indicatessig- der with sphericalends, I-beam frame structure,were investigated.The nificantdeviations from the returnsexpected when incoherent scattering is objectswere created in an object-orientedray tracingsoftware package and dominant.The peaktarget strength is reducedand the resonance frequency renderedat vaxiousorientations to describethe reflective properties.A is shifteddue to multiplescattering. The targetstrength also varies strongly separateprogram was writtento decodethe ray tracedimages of the ob- with frequencyas a resultof interferenceeffects. For widely dispersed jects anddetermine their targetstrength. Current work will yield resultsto ensembles,the modelreproduces the resultsof incoherentscattering. For be comparedwith the empirical high-frequencytarget strengthanalysis largerensembles the modelpredicts target strength values near the main results obtained at Naval Surface Warfare Center for Naval Research Labs resonancewhich diminishsharply with depth.The effectsof a schoolon andat CooperUnion's Acoustical Research Center. the scatteringof any singleindividual within it becomegreater as the •hool sizeincreases. By reducingthe viscousdamping in the scattering kernel,the modelcan alsodescribe scattering from small bubbleclouds. 3:20 2:20 5pUW9. A generalized wave-number method for solving waveguide scatteringproblems. JohnA. Fawcett (SACLANT UnderseaRes. Ctr., 5pUW6. Acousticwave scatteringfrom infinite cylindricalclad rods. Viale SanBartolomeo, 400, 19038La Spezia,Italy) FarhangHonervat (Dept. of Mech. Eng., Univ. of Toronto,Toronto, A generalplane-wave decomposition method for solvingscattering OntarioM5S IA4, Canada)and AnthonyN. Sinclair (Univ. of Toronto, Toronto,Ontario M5S IA4, Canada) problemsfor objectsin a possiblyrange-dependent oceanic waveguide is presented.The waveguide'sinterfaces and objectswithin the waveguide This paperconsiders the scatteringof an infiniteplane acoustic wave arecharacterized by plane-wavescattedng matrices. The totalresponse of obliquelyincident on an infiniteclad rod. Comparing the form functions of the mediumcan be computedby combiningthese matrices using an in- the scatteredpressure for the clad rod and a simple rod madeof the variantembedding approach. This operatorformalism is independenlof claddingmaterial, it is observedthat the presenceof the corewill affectthe the methodused to solvethe individualfree-space objector interface scat- lower moderesonances while the highermodes are not affected.The ratio teringproblems. The methodis derivedfrom the theoryof generalized a/b, wherea and b are the radii of the core and the clad rod, respectively, reflectionoperators lB. L. N. Kennett,Wave Motion 6, 419-429 (1984)] is an indicationof the boundarybetween the lower and higher modes. andis alsoclosely related to someT-matrix formulations [G. Kristensson Additionalresonances for thiscase are due to the surfacewaves propagat- and S. Str•m, J. Acoust.Soc. Am. 64, 917-936 0978)]. The generalized ing on the core/claddinginterface. These resonances axe highly dependent wave-numbermethod is usedto computescattering from a cylinder in on the qualityof the bondbetween the core and the cladding.Hence they perfectand penetrable waveguides. The caseof a bottomsloping interface could be usedas key parametersin 8valuationof the interfacialbond is alsoconsidered. For someof the examples,a comparisonis madewith quality.A finite valueof bondrigidity is usedin orderto modelthe core/ the resultsfrom othercomputational techniques. claddingboundary. Using this approach the quality of the interfacialbond in the modelcan range for perfectbonding to completedebond depending on the valuesof the boundarystiffness constants. 3:35 2:35-2:50 Break 5pUWI0. Soundscattering by a fluid-filledcylindrical shell in water. GregoryKaduchak and Charles M. Loeffler (Appl. Res.Labs., Univ. of Texas, P.O. Box 8029, Austin, TX 78713-8029) 2:50 Previouscalculations and observationsof backscatteringby cylindrical shellsin water usuallyinvolve shells which are eitherempty or subjectto 5pUW7. Low-frequency volume scattering measurement• from the extremelylight interiorloading conditions such as air. Typicalecho sig- central Mediterranean. Mark J. Vaccaro (Naval UnderseaWarfare Ctr., New London, CT 06320} naturesdisplay distinct contributions described by specularreflection and guidedwaves launched along the shell structure.The presentresearch Broadband(200-1500 Hz) measurementsof directpath volume scat- analyzesthe backscatteringeffects as a consequenceof fillingthe interior teringwere madein May of 1991in thecentral Mediterranean's Ionian Sea cavitywith a higherimpedance fluid such as water. Energy transferred into and adjacentMedina Bank.Acoustic sources used in thesemeasurements thecavity couples into radiation mechanisms which drastically increase the wcrc explosivecharges detonated several hundred meters below a vertical fine stmcture in the backscatteringform function. Dispersioncurves de- line array(VLA) receiver.Reverberation was processed from the upward lookingend-fire beam of the VLA yielding highly resolvedscattering displaya complicatedmode structure which is a combinalionof theguided strengthsin depthand frequency for the upper400 m of the watercolumn. wavesfound on a cylindricalshell in vacuumand the normal modesof a Analysisof the spectralcharacteristics of the volumescatter data reveals fluid-filledcylindrical cavity satisfyingrigid boundaryconditions. The ra- thatthe dominant scattering emanates from diffuse, broadband strata which diationdamping of theassociated curves yields insight into mechanisms of 3423 J. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 rivedfromfull129th3-D Meeting:elasticitytheoryAcoustical viatheSociety Watson of transform America methodology 3423 I Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp energytransfer to andfrom the internal cavity through the guided Lamb 4:20 wavestraveling along the shell.The cylindricalshells studied are excited 5pUW13. Modeling of backscattering by bottom volumetric by planewaves at normalincidence and have radius to thicknessratios of 5% and 10%. inhomogeneities. Dajun Tang (Dept. of Appl. Ocean Phys. & Eng., WoodsHole Oceanogr.Inst.. WoodsHole. MA 02543) 3:50 It has been recognizedthat when a soundwave encountersthe ocean bottom.part of theenergy will be scatteredby volumetricinhomogeneities 5pUWI1. A perturbative techniqueto compute scatteringof in the bottom.To simplifythe mathematics.previous efforts in modeling interfacewaves from pointlikeobstacles. Eric Smith (Appl. Res. the volumetricscattering process invoke some forms of plane-waveap- Labs., Univ. of Texas,P.O. Box 8029, Austin,TX 78713-8029) proximationto either or both of the forwardand backwardpropagating fields:Since the oceanbottom has different acoustic properties from thatof A techniqueis presentedto computea scatteringamplitude for waves the watercolumn, particularly since it oftenhas a morecomplicated struc- from a pointlikeinhomogeneity in an elasticmedium with boundary,into ture. introductionof the plane-wave approximationcasts clouds on the interfaceas well as bulk modes.The particularsystem considered is a validity of the modelingresults. Here an approachis presentedthat uses half-spaceof fluid overlyinga half-spaceof a liner elasticsolid, with the the exactforward and backwardpropagating fields and calculates the back- obstacleplaced in the solid very near the boundary.The object of the scatteringstrength numerically in the spatial domain. The bottom is as- calculationis to constructa perturbationtheory in layeredmedia in which sumedto be generallylayered with superimposedrandom scatterers which the scatteredwave respectsthe boundaryconditions at each perturbative have given correlationfunctions. Finally the validity of this model and its order. This can then be used to estimate and qualitatively analyze the rangeof applicabilitywill be discussed. significantfeatures of suchscattering, and to producea well-definedyet simplealgorithm for approximatingexact solutions. [Work supported by 4:35 theU.S. Navy, Office of NavalResearch.] 5pUW14, Using matched-field processingtechnique to map the 4:05 forward-scatteredsignal. Yung P. Lee (Sci. ApplicationsInt'l. Corp., 1710 GoodridgeDr., MS T1-3-5. McLean. VA) 5pUW12. Extraction of target characteristicsfrom the responseof a ribbed cylindrical shell in a shallow water environment. Angie Matched-fieldprocessing combines an acousticpropagation model Sarkissian,David H. Hughes,and Louis R. Dragonette(Naval Res. Lab., with matched-filterprocessing to localize a source•n three-dimensional Washington,DC 20375-5350) space.It has been shownto be effective in discriminatingpassive sources both•n rangeand depthby exploitingthe verticalstructure of the signal. Bistaticand monostatictarget strength values of a ribbed cylindrical Reverberation.especially the surface-scatteredenergy, is the primarycon- shellcontain various scattering phenomena such as Bloch waves,rib reso- cern for active systems.Surface scattering occurs near the oceansurface. nances,specular reflections and other effects due to wavestraveling on the Sincematched-field processing can discriminatein depth,it may poten- surfaceof the shell.When the targetis placedin a shallowwater environ- tially providesignificant clutter suppression for activesystems. In a sea ment, the responseis further clutteredby the presenceof the various test, a verticalarray was deployedand a cw sourcewas mooredfrom a multipathsthat a signaltravels in a boundedmedium. By usinga vertical stationaryplatform approximately18.6 km away from the array. The line arrayof sourcesand receivers, the targetresponse may be extracted.A forward-scatteredenergy was spectrallyseparated from the carrier and Verticalarray of sOUrcesis usedto suppresscertain shallow water modes in then MFP was performedto examinethe spatialdistribution of the scat- the incidentfield. A receiverarray is usedto removecertain shallow water teredenergy. MFP successfullymaps the scatteredenergy near the surface. modesfrom the scatteredfield. Timeffrequencyanalysis is a final filter for Simulationswas done by generatingrealization of an ocean surfacewith selectingthe modesof interestfor which the targetresponse is extracted. randomly distributedsurface waves and a modified FEPE was used to The extracted target responseis correlated against the free field target propagatesignals to a vertical array. Resultsof this simulationshow that characteristicspreviously determined by time-frequencysynthesis tech- MFP also successfullymaps the simulatedscattered energy near the sur- niques. face.[Work supported by U.S. Navy.] 3424 d. Acoust.Soc. Am., Vol. 97, No. 5, Pt. 2, May 1995 129thMeeting: Acoustical Society of America 3424 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp