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On the relations among temporal integration for loudness, loudness discrimination, and the form of the loudness function. (A)
Poulsen, Torben; Buus, Søren; Florentine, M
Published in: Acoustical Society of America. Journal
Link to article, DOI: 10.1121/1.415616
Publication date: 1996
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Citation (APA): Poulsen, T., Buus, S., & Florentine, M. (1996). On the relations among temporal integration for loudness, loudness discrimination, and the form of the loudness function. (A). Acoustical Society of America. Journal, 99(4), 2490-2500. DOI: 10.1121/1.415616
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PROGRAM OF
The 131st Meeting of the AcousticalSociety of America
Hyatt RegencyIndianapolis Hotel © Indianapolis,Indiana © 13-17 May 1996
NOTE: All Journalarticles and Letters to the Editor are peer reviewed before publication.Program abstracts,however, are not reviewedbefore publication,since we are prohibitedby time and schedule.
MONDAY MORNING, 13 MAY 1996 CELEBRATION B, 8:00 TO 11:50 A.M.
Session laAO
AcousticalOceanography: Inversions for Surface, Volume, and Bottom Properties
Nicholas C, Makris, Chair Naval ResearchLaboratory, 4555 OverlookAvenue, N. W., Washington,DC 20375
Chair's Introduction--8:00
ContributedPapers
8:05 8 km along a 40-kin tomographytransect showed that the frequencyre- sponsewas mostlyflat with high transmissionloss at selectedfrequencies. laAO1. Estimating surface orientation from sonar images. Nicholas This differs from often observedfrequency dependence in other shallow- C. Makris (NavalRes. Lab., Washington, DC 20375) water environmentswhere there is some low frequencywith minimum Sonar imagesof remote surfacesare typically corruptedby signal- loss,suggesting an optimumfrequency of propagation.Range-dependent dependentnoise known as speckle.This noisearises when wavelength geoacousticand seismicdata along the transectand wa•er sound-speed scaleroughness on the surfacecauses a randominterference pattern in the data measuredduring the acoustictransmissions permitted the develop- soundfield scattered from it by an activesystem. Relative motion between ment of a realisticenvironmental model. Normal-mode modeling results source,surface, and receiver cause the received field to fluctuate over time with C-SNAP indicatedthat the presenceof a soft clay top layer with a with complexGaussian statistics. Underlying these fluctuations, however, speedless than the watercolumn was a decisivefactor in the observed is the expectedradiant intensity from the surface,from which its orienta- frequencydependence, since it actedas an alternativewaveguide to lower- tionmay be inferred.In manycases of practicalimportance, Lamberfs law order modes.The modeledfrequency dependence and absolutelevel of is appropriatefor suchinference because variations in the projectedarea of transmissionloss closely agreed with the measurementsobtained at the a surfacepatch, as a functionof sourceand receiverorientation, often differentranges and depths,resulting in a validationof theoreticalargu- causethe predominantvariations in its radiance.Therefore, maximum mentsinvolving selected frequencies of hightransmission loss as a major likelihood estimators for Lambertian surface orientation are derived. These featureof this type of environment. are asymptoticallyoptimal when a sufficientlylarge numberof indepen- dent samplesare available,even thoughthe relationshipbetween surface orientationand measuredradiance is generallynonlinear. Here, the term 8:35 optimalmeans that the estimateis unbiasedand its meansquare error equalsthe Cramer-Raolower bound,which is alsoderived. The requisite laAO3. Inversion techniques for characterizing a coupled mode numberof independentsamples necessary for asymptoticoptimality of the acousticwaveguide. Daniel Rouseff and Martin Sideflus (AppLPhys. maximumlikelihood estimate is givenfor somespecial cases. Lab.,Univ. of Washington,Box 355640,Seattle, WA 98105)
8:20 A methodfor characlerizinga range-dependentacoustic waveguide by remotesensing is examined.The approachis to transmitfrom a limited laAO2. Broadbandfrequency response modeling for inversionof a numberof sourcelocations and measurethe propagatingfield along a shallow-water waveguide with a range-dependentsoft clay bottom verticalarray. Characterization of the environmentis castas an inverse (Yellow Shark '95 experiment). RaymondI. Soukup (Naval Res.Lab., problemwhere the goal is to determinethe mode couplingcoefficients Washington. DC 20375-5320), Jean-Pierre Hemand, and Enzo from the acousticalmeasurements. Ideally, measurementsfrom the source Michelozzi (SACLANT UnderseaRes. Ctr., 19138La Spezia,Italy) at a single location should suffice to characterizethe medium when the During the Yellow Shark '95 experimentthe broadbandfrequency re- propagationis adiabatic.When thereis coupling,the problemis underde- sponse11200-800 Hz) of a shallow-waterwaveguide was measured for the refrained and unstable if the number of source locations is less than the purposesof performingmultimodal inversion of itsacoustic and geoacous- numberof propagatingmodes. Tikhonov regularization is usedto build tic properties.Measurements from vertical receiving arrays deployed every stability into the inversionalgorithm. The numberof measurementsre-
2449 J. Acoust.Soc. Am., VoL 99, No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society of America 2449
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 quiredis shownto be directlyrelated to the natureand extent of the mode problem.An analyticexample is givenin whichboth maximum and mini- coupling.The methodis demonstratedby numericalsimulation for two mum traveltime eigenraysexist. Conditions for ray chaosin the analytic shallowwater scenarios: a slopingbottom and a randomlyrough bottom. exampleare derived and related to theoccurrence of maximumtravel time [Worksupported by ONR.] eigenrays.[Work supported by NRL.]
8:50 9:35
laAO4. Time-domain shallow-water environmental inversion using laAO7. Computer modeling of the process of the ocean stream unknown broadband sources. lacob Roginsky (Naval Res. Lab., velocity remote acoustics sensing in Fram Strait environmental Washington,DC 20375) condition. Igor B. Esipov (N. AndreyevAcoust. Inst., 117036,Moscow, Inversionfor environmentalparameters using both simulatedand ac- Russia),Ola M. Johannessen(Nanecn Environ. and RemoteSensing Ctr., tualexperimental data was performed based on thepropagation results for N-5037 Solheimsviken-Bergen,Norway), KonstantinA. Naugolnykh presumablyunknown broadband sources. The environmentis a shallow- (CIRES/Environ.Technol. Lab., Boulder,CO), Oleg B. Ovchinnikov, waterenvironment and all computationsare performed in thetime domain. Yury 1. Tuzilkin, and Viktor V. Zosimov (N. AndreyevAcoust. Inst., The inversionis basedon the least-squarecomparison between the results 117036,Moscow, Russia) of a sourcedeconvolution for each of severalreceivers. Because single- An importantpart of the generalproblem of globalclimate change is receiversource deconvolution in underwateracoustics is an intrinsically the measurement of the heat inflow from the Atlantic ocean to the Arctic ill-posedproblem, the Tichonor-Philips regularization is incorporatedinto basin.An effectivetool to measureit is the acousticmethods application. the currentprocedure. The methodis madeefficient by the useof a new Someaspects of this problemconnected with the averagewater tempera- deeouvolutionalgorithm that specificallytakes advantage of the triangular rare measurementswere consideredpreviously [Naugolnykh et al., J. Tocplitzstructure of thepropagation matrix [J. Roginskyand G. W. Stew- Acoust.Soc. Am. 97, 3264(A) (1995)]. In the presentpaper the resultsof art, J. Acoust.Soc. Am. 97, 3290 (A) (1995)]. The advantagesof this computermodeling of theocean stream velocity remote acoustical sensing methodare: (a) The processcan be performedwith as few astwo receivers; with respectto the Fram Straitenvironment are presented.The computer (b) noa priori sourceinformation is required;(c) dueto one'sability to simulationof the random environmentcharacterized by the 3-D sound- work with shortertime windows,the procedurecan be madefaster than a speedfield wasperformed. This processhas been done with the assump- correspondingfrequency domain approach. [Work supported by ONR.] tion of bothregular temperature changing in the crosssection of the Fram Straitand isotropicrandom sound-speed variation distribution in the plane in each horizon.Spatial spectra of simulatedinbomogeneities can be cor- 9:05 rectedin the courseof modeling.Simulated fields of environmentalinho- mogeneitieswere usedfor the soundsignal propagation modeling through laAO5. Robust ray path identification for ocean acoustic the pathsdirected crosswise and alongthe water flow to compareDoppler tomography. Max Deffenbangh(Dept. of Elec.Eng. and Cornput. Sci., and scintillationmethods of streammonitoring. MIT, Cambridge,MA 02139),Henrik Schmidt (M1T, Cambridge,MA 02139), and JamesG. Bellingham (MIT Sea Grant, Cambridge,MA 02139) 9:50-10:05 Break
Acoustictomography in a ray environmentis a two-stepprocess. First, eachmeasured ray arrivalfree in the receivedmultipath structure is iden-
tifiedwith a particularpredicted ray path.Second, the differences between 10:05 the measuredarrival times and the predictedarrival timesfor the repre- sentedray pathsare usedin a linear inversionto calculatecorrections to laAO8. Mode couplin• effect of a cold eddy in Taiwan's Northeast parametervalues describing the sound-speedstructure. If measuredarrival Sea. Chi-FangChen (Dept.of NavalArchitecture and Ocean Eng., Natl. times are identifiedwith the wrongray paths,errors will resultin the linear Taiwan Univ., Taiwan, R.O.C.) inversion.In deepocean tomography, the time spacingbetween ray arriv- als is typicallylarge compared to theparameter induced changes in arrival The Kuroshiocurrent turns toward the north-eastwhile it passesthe times, so ray path identificationis not difficult. In shallowwater, however, Okinawa Trough in Taiwan's NortheastSea. In this region, there are dif- my path identificationcan be morechallenging. An algorithmis presented ferent watersmixing, namely,water from the Taiwan Strait, water of the thatcombines the ray pathidentification step with the linearinversion step East China Sea, and the Kuroshiocurrent. During the year,excepl for the to allow tomographyusing rays where the parameterinduced arrival time summermonths, the Kuroshiocurrent is characterizedby its distincttem- shifts may be larger than the time spacingbetween arrivals. The perfor- peraturedifference from other waters,i.e., the Kuroshiofront and cold manceof the algorithmis simulatedfor a typicalshallow-water environ- eddiesare two predominantfeatures in this region.The frontal effect on ment.[Work supported by ONR.] acousticpropagation has been studied and reported in a previoustalk. In this paper,the couplingeffect of modeswhen acousticsignals transmit throughthe cold eddyusing both the ParabolicEquation method and the AdiabaticMode Approximation is reported.Severe mode coupling is re- alizedwhile the soundtransmits through the cold eddy. [Work supported by National ScienceCouncil of Republicof.China.] laAO6. Second-orderanalysis of eigenray displacement:When does Fermat's principle apply? B. Edward McDonald, Michael D. Collins (Naval Res. Lab., Washington,DC 20375), and Ira B. Bernstein (Yale
Univ., New Haven, CT 06520) 10:20 In the oceansound channel multiple eigenrays,each possessingsta- ICAO9. Multimodal dispersionidentification. JamesPoplawski and tionarytravel time, may connecttwo fixed points.In a highly structured TedBirdsall (Dept.of Elec.Eng. and Cornput. Set., Univ. of Michigan, propagationenvironment, how doesone determineif the travel time of a 1301 Beat, Ann Arbor, MI 48109) given eigenrayis a local minimum(Fermat's principle), maximum, or saddlepoint with respectto ray parameters?A second-orderanalysis of the Geometricdispersion in the deep ocean soundchannel causes wide- travel time integral along an eigenrayis carried out to reveal conditions bandmodal arrivals to be spreadsignificantly in time at long ranges.This determiningthe natureof the stationarity.In three dimensions,the problem resultsin a low modal peak signal-to-noiseratio and interferencedue to reducesto a second-orderdifferential/diadic eigenvalue equation along the multiple overlappingarrivals. These effects make the identificationof in- ray. In two dimensions,it becomesa scalar Sturm-Liouville eigenvalue dividualmodal arrivals difficult without the useof a verticalreceiving
2450 d. Acoust.Soc. Am., VoL 99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2450
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 array.The time compressionof modal arrivalsusing phase-only filters is estimatedusing seismicreflection/refraction when acousticray paths and examinedas a methodfor locatingand identifyingarrivals from a recep- travel time can be identified and measured from the data. Due to the tion at a singledepth. A searchdisplay, dubbed the dispersiondiagnostic shallow depth in shallow water, the many multipaths due to bottom display,has proved its worth in computersimulations using a 60 mode reflection/refraction make such identification and measurement rather dif- rangeinvariant model of SLICE89 propagation.The DD displaysimulta- ficult.A full fieldinversion technique is presentedwhich uses a broadband neouslyshows a raylike(no 'dispersion) structure and a patternedmodal sourceand an easilydeployable array for bottomsound speed and reflec- structurewith stronglydispersed early arrivalsand lightly dispersedter- minalarrivals. [Work supported by ATOC.] tivity inversion.The techniqueis a modifiedmatched-field inversion tech- niquereferred to as matchedbeam processing. Matched beam processing usesconventional beamforming processing to transformthe fielddata into
10:35 the beamdomain and correlatethat with the replicafield alsoin the beam domain.This allowsthe analysisto trackthe acousticfield as a functionof laAO10. Improved empirical orthogonal functions for ocean incidence/reflectedangle and minimizecontamination or mismatchdue to acoustic tomography. Max Deffenbaugh (Dept. of Elec. Eng. and sidelobeleakage. This techniqueis illustratedwith simulateddata for a Comput.Sci., MIT, Cambridge,MA 02139) and Henrik Schmidt (MIT, verticalarray and can be generalizedto otherarray configurations, such as Cambridge,MA 02139) a towed array. The method of empirical orthogonalfunctions is commonlyused in tomographyto selecta set of basisvectors to representvariations in the sound-speedprofile. In this method,historical profiles are usedto estimate a profile covariancematrix, and the eigenvectorscorresponding to the largesteigenvalues of the covariancematrix are taken for the basisvectors. Thesebasis vectors are the mostefficient parametrization of the variations 11:20 in theprofile. They are NOT, however,the parametrizatlonwhich leads to laAO13. Determinationof sub-bottomsediment properties and their the mostaccurate post-measurement estimate of the profile,because, in a tomographicexperiment, all profilevariations cannot be measuredwith the spatialdistributions from chirp sonardata. AltanTurgut (NavalRes. sameaccuracy. In thispaper, the setof basisvectors, which will yield the Lab.,Acoust. Div., Washington,DC 20375) least error in the post-measurementestimate of the profile, are derived takinginto account measurement resolution and measurementnoise. These Determinationof impedanceand attenuationcoefficients for upper improvedempirical orthogonal functions are appliedto severalcanonical sedimentlayers from chirp sonardata is performedby using simulated problemsin oceanacoustic tomography, and the resultingenhancement in annealingalgorithms. Normal incidence reflection seismograms are calcu- estimationaccuracy is demonstrated.[Work supported by ONR.] latedfor layeredmarine sediments using the Blottheory of acousticwave propagationin porousmedia to producesynthetic data. A time-domain inversionalgorithm progressively identifies each reflectionand applies 10:50 randomperturbations to correspondingmodel parameters to minimizethe laAOll. Estimation of stochastic wave-number variations at the quadraticdeviation between the dataand syntheticseismograms. Numeri- Atlantic Generating Station site and comparisonwith acousticdata. cal simulationsindicate that suchan inversionscheme can be efficiently Michael J. Longfritz (Rensselaer Polytechnic Inst., Troy, NY usedto surveylarge areas for characterizationof sedimentproperties and 12180-3590),Mohsen Badicy (Univ. of Delaware,Newark, DE 19716), theirspatial distributions. In addition,impedance and attenuation estimates William L. Siegmann,Melvin J. Jacobson,and Indra Jaya (Rensselaer are usedto predictthe sedimentporosity, density, permeability, and sound PolytechnicInst., Troy, NY 12180-3590) speedusing the Blot theory. Finally, chirp sonar data (3 to 7 kHz) collected The estimation of horizontal wave-number variations in a stochastic onthe New JerseyShelf as a partof SWARM-95(Shallow Water Acoustic shallow-waterenvironment at theAtlantic Generating Station (AGS) siteis RandomMedia) experiment are analyzed. Inversion results confirm previ- constructed.A method using empirical orthogonal functions has been de- ouscoring and in situobservations that alternating sand and clay layers are veloped[Longfritz et al., J. Acoust.Soc. Am. 97, 3316 (A) (1995)]to presentat the HudsonApron site. relate wave-number fluctuations to environmental variations. First, the AGS site is modeled as a stochastic shallow channel with a range- dependentlayered sediment bottom. The layerinterface depths and intra- layersound speeds are treatedas randomvariables. Then, the estimation procedureis appliedto a particularpropagation track, where geoacoustic profilesand acousticsmeasurements are both available.Environmental 11:35 profilesalong the track am treated as a samplefrom a stochasticensemble. Estimatesare obtainedfor both the rangevariance of the wave numbers laAO14, Radiation impedanceof a circular vibrating plate on the and the particulardeviations associated with eachprofile in the sample. surfaceof viscoelasticmedia. MasaoKimura (Dept. of OceanEng., Comparisonsare made between results from the estimation procedure and TokaiUniv., 3-20-10rido, Shimizu,Shizuoka, 424 Japan) simulationsfrom the KRAKEN propagationcode. In a separatestudy, acousticalwave numbershave beengenerated from experimentaldata for Radiationimpedance of a vibratingplate on the surfaceof a visco- thetrack using a methodof Thomson.The estimation results are compared elasticmedium such as marinesediment varies with the viscoelasticprop- to this data. ertiesof the medium.Therefore, it is possibleto predictthe viscoelastic propertiesusing the characteristicsof the radiationimpedance. In this paper,the characteristicsof radiation impedance of a circularvibrating 11:05 plateon the surfaceof viscoelasticmedia were obtained by numerical laAO12. Acoustic inversion of bottom reflectivity and bottom analysis.The resultsshowed that the values of ka (k is the wavenumber, sound-speedprotile in shallow water. I. C. Yang (Naval Res. Lab., a is the radiusof a circular vibrating plate) at which the imaginary pan of Washington,DC 20375)and T. Yates (VectorRes. Co., Inc.,Rockville, the radiationimpedance becomes zero can be relatedto the ratioof the MD 20852) shearwave velocity to thelongitudinal wave velocity, that is, thePoisson's Thispaper presents a full fieldtechnique to invertbottom sound profile ratio.Next, measurementsof radiation impedance for threekinds of ure- andbottom reflectivity from acoustic data collected in shallowwater. Bot- thanerubbers and two kindsof dry beachsands were done, and the mea- tom sound-speedprofile and bottomreflectivity have been traditionally suredvalues were compared to the calculatedvalues.
2451 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2451
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 MONDAY MORNING, 13 MAY 1996 MT. RUSHMORE, 9:00 A.M. TO 12:00 NOON
Session IaSC
SpeechCommunication: Informal Workshop on Voice PerceptionI
David B. Pisoni, Cochair SpeechResearch Laboratory, Department of Psychology,Indiana University, Bloomington. Indiana 47405
Jody Kreiman,Cochair Universityof California,Los Angeles, Head/Neck Surgery, 31-24 Rehab,Los Angeles, California 90024-1794
The goalof this informalworkshop is to bringtogether several researchers working on variousaspects of voicepercepfon. Historically,the studyof voicehas been treated as a more-or-lessautonomous area quite distinct from other research problems in speechand hearing sciences. In thisworkshop, some of thetraditional problems of voiceclassification and perception will bediscussed andreviewed and then these efforts will be relatedto recentfindings in speechperception and spokenword recognition which have shownimportant dependencies between traditional voice parameters and perceptual analysis of the speechsignal. The contributorsto the sessioninclude: lody Kreiman,Diana VanLancker, Keith Johnson, Robert Remez, Peter lusczyk, and David Pisoni. Please bring yourslides and overheads and join in the discussionon somelong-standing problems related to the "indexical"and "linguistic" functionsof speech.For furtherinformation about this informalworkshop, please feel free to contactD. B. Pisonivia E-mail: [email protected] with an interest in speechperception, production. and spoken language processing is welcome to attend and contributeto the discussionof theseproblems.
MONDAY AFTERNOON, 13 MAY 1996 CELEBRATION B, 1:00 TO 5:35 P.M.
Session1pAO
AcousticalOceanography and UnderwaterAcoustics: Ambient Noiseand Inversionsin the Surf Zone
Grant B. Deane, Chair Marine PhysicalLaboratory, Scripps Institution of Oceanography,La Jolla, California 92093-0238
Chair's Introduction--l:00
Invited Papers
lpAOl, Ambientnoise from the surf zone:Surface and acousticwaves. W. KendallMelville (ScrippsInst. Oceanogr., U.C.S.D., La Jolla, CA 92093-0213)
Wave breakingis probablythe dominantsource of ambientnoise in the ocean.In deepwater, breaking is intermittentin bothspace and time, but, in the surf zone,every wave of any appreciablesize breaks,or shoals,before it reachesthe shore.This makesthe surf zone and its neighboringregion offshore acoustically different from deeperwaler. In shoaling,surface waves dissipate their energy, generatecurrents and turbulencethat mix the watercolumn, suspend sediments and entrainbubbles, and generatesound. It is the potentialrelationships between the soundgeneration and propagationand the otherphysical processes associated with surfacewaves, and the shoalingbottom topography, that is the subjectof this talk. This is an openfield in acousticaloceanography and underwater aeouatieg,with few measurementsavailable but a great deal of potential.In thin lecturethe processesassociated with the shoalingof surfacewaves will be reviewedand the resultingimplications for soundgeneration and propagation will be discussed.The potential for the inversionof acousticdata to infer othersurf zone processes will be explored.
1:25
IpAO2. Recentresults in surf zoneambient noisemeasurements. Ellen S. Livingston (Office of Naval Res.,Code 321,800 N. QuincySt., Arlington,VA 22217-5000)
Over the yearsonly a few measurementshave been madeof surf zone ambientnoise. Recently, however, several sets of data have beentaken in and near the surf zone in conjnnctionwith coastaloceanography and seismoacousticstudies. In this talk, an overview is givenof pastand present surf zone studies aud differing approaches are discussed and contrasted. The varietyof resultsnow starting to comeforward from the new da•a are outlined. Importmtt issues opened by theserecent results and new applications anticipated are discussed as well.
2452 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2452
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
lpAO3. Surf noise and biologicalsounds in the near-surf-zoneenvironment. Gerald L. D'Spain, William $. Hodgkiss, William A. Kuperman,and Lewis P. Berger (MarinePhysical Lab, ScrippsInst. of Oceanogr.,San Diego, CA 92106)
The Marine PhysicalLab's Adaptive Beach Monitoring Experiment was conducted from 24 April to 14 June1995, in and nearthe surfzone off the S. Californiacoast. Other participants included NRaD/NCCOSC, NRL, ARL/PSU, andARL/UT. The focushere is on the underwateracoustic noise field properties.Contributions of breakingsurf are studiedin the 1- to 400-Hz band using a 35-elementsubsection of a bottomhydrophone array oriented perpendicular to the coastand located3.4-km offshore in 20-m water. A 3-weektime seriesof endfire-beamformingresults are comparedto the oceansurface wave heightdata collected over the same period.Source tow dataquantify the propagationeffects of surf noiseto the array site and permitinversions for bottomgeoacoustic properties.The arraydata are supplementedby the distancedependence from shoreof data from bottom-mountedsonobuoys in the 100-Hz-20-kH2 band,and air acousticdata recorded just landwardof the shoreline.Biologics are a substantialcomponent of the noise field and must be accountedfor in evaluatingthe contributionfrom surf. Fish soundsthemselves can be used as novel sourcesin inversionfor bottomgeoacoustic properties. [Work supported by ONR, Code32.]
2:05
lpAO4. Matched-fieldinversion in a rapidly fluctuatingshallow-water waveguide. NicholasC. Makris (Naval Res. Lab., Washington,DC 20375)
A nu•nberof usefulapplications for matched-fieldinversion have been envisioned for thelittoral zone. These include the estimation of environmentalparameters, such as the sound-speed structure of thewater column and geoacoustic properties of thesediment, as well as the moretraditional localization of submergedobjects. However, natural disturbances such as passingsurface and internalgravity wavesoften placeshallow-water waveguides in sucha stateof flux that a signal,deterministic when transmittedfrom a source, becomesfully randomizedafter propagating only severalchannel depths away in rangeto a receiver.When not properly accounted for, suchrandomization can severely degrade the accuracy of a matched-fieldinversion, which presumably is for parametersthat remained fixed during the measurementprocess. Therefore, the generalperformance of a matched-fieldinversion is examinedfrom the perspectiveof statisticalestimation, under the worstcase scenario of a waveguidethat may be fluctuatingrapidly during a given transmissionor set of transmissions.Specific examples for shallow-watermatched-field tomography and objectlocalization using ambient noise are then considered.
2:25
lpAO5.Shallow-water ambient noise caused by breakingwaves in thesurf zone. OscarB. Wilson,Marc S. Stewartal (Naval Postgrad.School, Dept. of Phys.,Monterey, CA 93943),James H. Wilson (NeptuneSciences, Inc., San Clemente, CA 92674),and RobertH. Bourke (Naval Postgrad.School, Monterey, CA 93943) Ambientnoise measurements made by Wilson,Wolf, andIngenito in MontereyBay, California in 1980and 1981were combined with modeledtransmission loss (TL) to estimatethe spectralsource level of surf-generatednoise. In the frequencyrange 20-700 Hz the horizontaldirectionality of thesenoise data showed much higher levels from shorethan seaward and the overallnoise levels decreasedwith range from shore, strongly suggesting that surf noise was a significantcontributor. A Hamilton geoacoustic model of the coastalenvironment has been derived and used in a finiteelement parabolic equation propagation loss model to obtainthe TL values.These indicate that propagation is significantlydependent on theenvironment and frequency, particularly near the surf zone. Estimatesof windand local wave noise intensity corrected for the localenvironment were subtracted from the totalmeasured noise fieldto determinethe contribution due to surfonly. Heavy surf breaking on a uniform12.5-km linear section of beachnear Fort Ord wasfound to be the dominantsource of surf-generatednoise. The preliminaryresults provide estimates of the noisesource level densitiesfor heavyand light surf at FortOrd beach. •lCurrently at NavalSea Systems Command, Arlington, VA 22242-5160.
2:45-3:00 Break
ContributedPapers
acousticfield was imagedwith and withoutthe targetpresent and both 3:00 passiveand active detection of thetarget was obtained. The measurements were carriedout in low sea stateswhen the primarysource of ambient lpAO6. Imaging of passive targets in shallow-water using an noisewas biological and strongly anisotropic. [Work supported by ONR.] ambient noise acousticimaging system. Marc P. Olivieri, StewartA. L. Glegg,and Robert K. Coulson (Ctr. for Acoust.and Vib., Dept.of OceanEng., Florida Atlantic Univ., Boca Raton, FL 33431) 3:15
This paperwill describean experimenton the detectionof passive lpAO7. Inversionof the underwatersound field to quantify the targetsin shallowwater using ambient noise as the solesource of insoni- formationof a subsurfacebubble layer. JeffreyA. Nystuen (Appl. fication.Glegg and Olivieri [Noise-Con 95, p. 1179]proposed a broadband Phys.Lab., Univ. of Washington,1013 NE 40thSt., Seattle, WA 98105) signalprocessing technique to achievethis type of passiveacoustic detec- tionusing a limitednumber of transducers.An arrayhas been developed to The underwatersound field can be usedto quantifyoceanic processes applythis technique in a shallow-waterenvironment. This paper will de- thatactively produce sound, including, for example,wind/wave breaking scribean experiment caffied out in Summer1995 off theBoca Raton inlet (windspeed) and rainfall. These "active" sound sources are subsequently in whicha targetwas successfully detected. The sizeof the targetchosen modifiedby the acousticenvironment. In the caseof wavebreaking or for this testwas 1.8X 1.2 m and it was placed40 m from the array.The rainfall, the sound source is located at the ocean surface. One of the
2453 J. Acoust.Soc. Am., Vol.99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2453
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 principalfeatures of thenear-surface zone in theocean capable of modi- respectively.The higherfrequency peak rapidly aU. enuates offshore, while fyingthe soundfield is the ambientbubble field. Frequency-dependent thelower frequency peak is essentiallyunattenuated over ranges of several modificationsof the underwatersound field duringheavy rainfall are ob- kilometers.In contrastto deepwater, the correlationof surfzone ambient served.Using a rainfallgenerated sound field as an example, the change in noisewith the local wind is poorsince the shoalingwaves may be domi- the spectralcharacter of the soundfield will be usedto quantifythe for- natedby swellfrom distant storms. Short term averages of acousticpower marionand decay of an ambientbubble field. Documentationof the for- correlatevery well with the amplitudemodulation (groupiness) of the mationof a bubblelayer has implications for gasand momentum exchange incidentwaves. [Work supported by ONR.] at the oceansurface by rainfall.
3:30
lpAO8. Acousticmeasurements of breakingwaves in the surf zone. 4:15 GrantB. Deane (ScrippsInst. of Oceanogr.,Mail Code0238, La Jolla, CA 92093-O238) lpAOll, Global directivity measurementsof near shore ambient noise. StewartA. L. Glegg, Marc P. Olivieri, and Robert K. Coulson A series of measurements have been made to characterize the sound (Cu. for Acoust.and Vib., Dept. of OceanEng., FloridaAtlantic Univ., generatedby breakingwaves in the surfzone around Scripps Pier. Simul- Boca Raton, FL 33431) taneousvideo and acousticdata were made to allow the acousticenergy radiatedby individualwaves to becorrelated with the breaking event at the In the summerof 1995 a shallow-waterambient noise experiment was surface.The acousticmeasurements were made directly below breaking carded out 1-mile offshoreof the Boca Raton Inlet. A volume array was wavesin 2 m of water and 170 m from the shoreline.Spectral analysis of deployedthat providedboth vertical and horizontaldirectivity measure- the data demonstratesthe presenceof a strongacoustic field below the mentsof the ambientnoise. This paperwill describethe array processing breakingwaves. Overhead waves generate sound for someseveral sec- algorithmused to obtainthe globaldirectivity measurements with high onds,and are clearly distinguishable from nearby surf. The breakingwave resolutionand presentthe ambient noise measurements.The results spectrumis bimodal,with two peaksin intensityaround 30 and 1000Hz. showedthat the ambientnoise was strongly anisotropic and dominated by A preliminaryanalysis of the datashows an acousticallyactive region of biologicalnoise from a local fishingpier locatedapproximately I mile to waterpropagating with the breaking wave. [Work supported by ONR.] the south. Measurements were also made of local boat traffic and it was found that the vertical arrival structurecould be separatedinto clearly definedbeams associated with eachbottom bounce along the propagation 3:45 path.[Work supported by ONR.] lpAO9. Preliminary characterizationand modelingof ambient noise due to highsurf during DUCK94. J. Paquin-Fabre(Neptune Sciences, Inc., 150 Cleveland Ave., Slidell, LA 70458) and James H. Wilson (NeptuneSciences, Inc., SanDiego, CA 92123)
Broadbandnoise due to surfthat propagates kilometers out to seawith 4:30 little transmissionloss has beenobserved for manyyears, but rarely di- lpAO12. Ambient noise generated by surface wind rectlymeasured and characterized. In Octoberof 1994a coastalresearch waves--Numerical and experimental results. Jin-Yuan Liu and experiment,DUCK94, wasconducted off the coastof Duck, North Caro• Chuen-SongChen (Dept. of Marine Environment,Natl. Sun Yat-sen line. NeptuneSciences, Inc., underNaval ResearchLaboratory sponsor- Univ., Kaohsiung,Taiwan 804, R.O.C.) ship,participated in that experimentwith the objectivesof obtainingam- blent noise data at offshore positionsfor investigationsof nearshore acousticnoise generatedby waves and surf. Measurementswere taken, Using a previouslydeveloped noise-generation model for sourcesdue using modified Navy standardsonobuoys, primarily during high surf to surfaceprocesses [W. A. Kupermanand F. Ingenito,I. Acoust.Soc. Am. events(wave heights of 1.7 to 2.4 Hmo,m).Preliminary analysis of the 67, 1988-1996 (1980)],a numericalstudy of ambientnoise, which incor- data indicates a broadband noise maxima between 400 and 600 Hz. In poratesrealistic wind wave spectrum(e.g., Pierson-Moskowitz),was order to characterizeambient noise due to surf for modelingpurposes, made for seismoacousticocean wave guides.The resultsdemonstrate a sourcelevel densitesfor heavy surf are currentlybeing developedusing closerelationship between the noisefield and the sourcefield, allowing the measuredAN dataand a finite elementparabolic equation transmission one to gain insightto the interplayof both fields.Experimental data of loss model. ambientnoise and wind waveswere collected in an experimentalsite near the centralpart of Taiwan.The measureddata were alsoused to generate numericalresults of ambientnoise which are thencompared with experi- mental data. The comparisonhas showna reasonableagreement in the 4:00 / frequencyrange dominated by the surfacewind wavesfor a receivernot lpAO10. Ambient noise measurements in the acoustic beach too close to bottom. By modeling the marine environmentas a shallow- monitoringexperiment. W.K. Melville, G. B. Deane,R. M. Shear,E. water seismoacousticwave guide, it was demonstratedthat the noise Terrill,and C. L. Epifanio (ScrippsInst. of Oceanogr.,U.C.S.D., La Jolla, modelof the noisefield was greatlyaffected by the sedimentproperties. CA 92093-0213) [Worksupported by NationalScience Council of Republicof Chian(Tai- wan).] During the spring of 1994 (April-June) the Marine Physical LaboratoryPSIOconducted the acousticbeach monitoring (ABM) pilotex- perimentat CampPendelton, CA. One componentof the experimentwas 4:45-4:50 Break concernedwith measurementof ambientnoise up to 40 kHz, at distances up to several kilometersoffshore. An array of three modified SSQ 57B sonobuoyswere mooredat distancesfrom 1.5 to 3.5 km offshore.The surf zone was instrumentedwith pressuregauges and a current meter, and a comprehensivemeteorological station was set up on the beach.A direc- 4:50-5:35 PANEL DISCUSSION tional microphoneon the beachwas usedto monitor the surf noise. Sup- portingoceanographic and meteorologicaldata was available from the SIO Panel Moderator: Grant B. Deane coastaldata informationprogram. Near-shore acoustic spectra are charac- Panelists:Gerald L. D'Spain,Ellen S. Livingston,Nicholas C. Makris,W. terizedby two broadpeaks in the rangesof 100-500 Hz and 1-7 kHz, Kendall Melville, Thomas G. Muir, Oscar B. Wilson
2454 J. Acoust.Soc. Am., Vol.99, No. 4, •t. 2, April1996 131stMeeting: Acoustical Society of America 2454
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 MONDAY AFTERNOON, 13 MAY 1996 CANYON HALL, 1:10 TO 5:00 P.M.
SessionlpMU
Musical Acoustics: Nonlinear Effects in Wind Instruments
DouglasH. Keefe, Chair BoysTown National ResearchHospital, 555 North 30th Street,Omaha, Nebraska 68131
Chair's Introduction--l:10
Invited Papers
1:15
IpMUI. Time-domainand frequency-domainexplorations of nonlineartryin musicalwind instruments. Neville H. Fletcher (Australian Natl. Univ., Canberra. Australia)
Nonlinearilyis an essentialfeature of the operationof sustained-tonemusical instruments, as well as beingan importanlfeature in many impulsivelyexcited instruments. Analysis of the behaviorof wind instrumentscan be approachedeither throughthe time domain,in which casethe linear resonantparts of the instrumentare characterizedby their impulseresponse, or in the frequency domain, in which casethe characterizationis in termsof mode shapesand frequencies.The generatormechanism in somecases has an embeddedlinear mode structure as well, but thereis an essentiallynonlinear coupling between it andthe main instrumentresonator. This paperexamines the differenttypes of information,or the complementaryviews of the sameinformation, that can be obtainedby time-domainand frequency-domainapproaches to wind instrumentacouslics.
1:45
IpMU2. Inferenceof nonlineareffects from spectralmeasurements of windinstrument sounds. James W. Beauchamp(School of Musicand Dept. of Elec.Eng., Univ. of Illinois,Urbana, IL 61801)
That wind musicalinstmmenls in conjunctionwith their playersare highlynonlinear can be inferredfrom measurementsof their outputspectra. These show that, for a givenperformed pitch, bandwidth generally increases with increasingrms amplitude. The cause of this harmonicgeneration is generallyattributed to a nonlinearpressure/flow excitation mechanism which interactswith the instrument'sresonant input impedancecharacteristic. Since there are no analyticalsolutions which predictmouthpiece spectra, one mustrely on simulationsand empirical measurements. Meanwhile, the pipe portion of the wind instrumenthas long been assumed to be a linearresonant system acting as a highpass filter with resonantminiroe corresponding to the inputimpedance maxima. This at least is true at low amplitudes.However, for the trombonelarge discrepanciesin the filter responsehave been found between measuremenlsmade with sinewave input and those made under actual performance conditions, particularly above resonant cutoff. The generaleffect is thatspeclral bandwidth (an attendanltonal brightness} increases even more with increasingamplitude than if the systemwere linear. There is nowevidence that this may be dueto shockwave formation in the pipeof the instrument.
2:15
lpMU3. Wind instruments:Some unansweredquestions. CornelisJ. Nederveen (Acacialoan20, 2641 AC Pijnacker,The Netherlands)
The basicsof functioningand tuningof wind instrumentsis reasonablyexplained by small-amplitudedescriptions. Some details mustbe cleared up, such as corrections at thehole/bore transition, bends, and radiation at holeends. In somecases, however, the linear descriptionfails. For example. a clarinet becomes unplayable when its usual holes are replaced by much smaller and shorter ones (of thesame impedance) [D. H. Keefe,J. Acoust. Soc. Am. 73, 1804-1820(1983)]. Since it wasnoted that this tube could be blown with another(i.e., a saxophone)mouthpiece, it was supposedthat the superimposedstatic flow influencesthe lube impedance.This assumptionwas provisionally confirmed by measurements.Understanding Ibis phenomenon may help to improvethe ease of playing of thelowest notes on saxophones. The common quantitative description of the flute action does not explain why certain fork fingerings cannotbe blownand why the "reed-flute"has a dominatingfifth harmonic in its initialtransient. To contributeto thediscussion on the influenceof wall vibrationson tonequality, a mechanismwill be proposedwhich is possiblyresponsible for a couplingbetween air and wall vibrations.
2:45
IpMU4. The measuredvocal tract impedancefor clarinetperformance and its role in soundproduction. Teresa D. Wilson (Schoolof Music,Box 353450,Univ. of Washington,Seattle, WA 98195) The role of the vocal lract in clarinetperformance has been investigatedby examiningthe vocal tract impedance.Z•. Theory predictsthat Zu peaksaligned with harmonics of thepitch frequency stabilize the oscillalion, The vocal tract impedance was measured directly wilh a one-microphonetechnique and indirectlyfrom a calculationusing lhe continuityof flow equation p. IZ.+p,tIZa=O. wherep, andP,t are the mouth and mouthpiece pressures and Z a is theinstrumenl impedance. The continuity equationwas verified for singletones and then used to examinethe role of thevocal tract in a varietyof musicalsituations. In orchestralexcerpts, the performer tends to alignresonances with the first and/or second harmonics, and there is somedependence on
2455 d. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April1996 131st Meeting:Acoustical Society of America 2455
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 musicalcontext. For multiphonics,the performercreates a resonancethat supports an oscillationat a linearcombination of the audiblepitch frequencies. For tonesplayed with pitchbend,induced by slackingthe jaw muscles,the playing frequency is controlled by thefrequency of a large-amplitudevocal tract resonance, for whichIz, 100-400cGa oh•. z, changesonly slightly when clariontones are playedwithout the registerkey. suggestingthat othervariables are involved.
3:15
lpMUS. Understandingthe operation of auxiliary fingeringson conical double-reedinstruments. RobertH. Cronin (360 MarmonaDr., MenloPark, CA 94025) andDouglas H. Keefe (BoysTown Natl. Res.Hospital, Omaha, NE 68131)
Playersof the modembassoon are accustomed to usingornate fingerings to stabilizeand correct certain notes that are difficult to tune.These "auxiliary" fingerings open or closetone holes far belowthe firstopen tone hole. The primarysubject of the investigation was a modemGerman-system bassoon. Calculations of impedanceversus frequency were madeusing a programbased on the Plitnik-Strongmodel of 1979,with severalextensions. The model,in turn,was validatedby comparisonwith measurementstaken with a systemdeveloped by Keefe et al. The authorsalso investigatedthe behaviorof auxiliaryfingerings on a replicabaroque bassoon,and sortedout a puzzling"feature" of a replicaRenaissance alto shawre-Based on this work, criteriafor "good" note behaviorare postulated. [Work supported by theInternational Double Reed Society.]
3:45-4:00 Break
ContributedPapers
4:00 4:30
IpMU6. A iinearized model of bassoonsound production: The role IpMU8. Influencesof sharp toroidal bendson the tuning of wind of auxiliary fingerings. DouglasH. Keefe (Boys Town Natl. Res. instruments. CornelisJ. Nederveen(Acacialaan 20, 2641AC Pijnacker, Hospital,555 N. 30th St., Omaha,NE 68131) and Robert H. Cronin The Netherlands) (Menlo Park, CA 94025) A toroidalbend causes tuning changes, which are modedependent and A quantitativetheory of soundregeneration in the bassoonhelps ex- mayamount to 10 cents.This is causedby a changeof the inertancein the plaindifferences in the playingfrequency and mouthpiece spectra associ- bend, whereasthe complianceis not affected.The inertartecchange was ated with the use of auxiliary fingerings.The linearizedcondition for studiedby Nederveen[Acoustical Aspects of WoodwindInstruments steady-stateoscillations at a frequencyf is O=Y(f)+ Ya(J); the air- (1969)], Rostafinski[•. Acoust.Sec. Am. 52, 1411-1420(1971)]. and columninput admittanceis Y(f) and the double-reedgenerator admittance Keefeand Benade [J. Acoust. Sec. Am_ 74, 320-332(1983)]. At firstsight, is Yo(f), whosereal partis negative(Fletcher, 1979; Thompson, 1979). the resultsseem different. However, it can be shownthat, at long wave- The generatoradmittance is basedupon a simple Bernoulli-typeflow lengths,they are essentiallythe same:The apparentdensity equals model, and the cane reed is medeledas a dampedoscillator. Model pa- PB= PB•12[ 1 - (1 - B2) •a], wherep is theunperturbed airdensity and rametervalues are empiricallydetermined and combinedwith measured B is the ratio of the tube radius and the tore curvature radius. The transition input admittances,allowing direct comparisonof Y(f) and -Ya(f) at of the torusinto the regularcylindrical bore causesa correctionwhich was frequenciesbelow and abovethe open tone-bolelattice cutoff frequency measuredby Keefe and Benade.This was verified by numericalcalcula- (Benade,1960). Auxiliary fingeringsproduce significant differences in tionsusing conformal transformations. The effectsof a toruson thetuning inputadmittance magnitude and phase above cutoff, and soundproduction canbe neutralizedby reducingthe bore in thetorus, for sharpbends of up is stabilizedfor a fingeringsuch that the lieearizedcondition is satisfied to some 5%. neara harmonicmultiple of the playingfrequency. The modelaccounts for intonationshifts associatedwith changesin auxiliary fingerings.While soundproduction in the bassoonis highlynonlinear, the fine structureof 4:45 the linearair-column response at frequenciesabove cutoff is an essential contributor.[Work partially supported by the InternationalDouble Reed IpMU9. Synchronizedoptical and acoustical measurementsof Society.] tromboneembouchure. JayC. Bulen (Div. of FineArts, Baldwin118, NortheastMissouri State Univ., Kirksville, Me 63501)
Outwardstriking- and inward striking-reed models have been proposed 4:15 for representingbrass players' lips [Sanoyesiet al., Acustica62, 194-210 IpMU7. Time-domainsimulation of an organ flue pipe. Seiji Adachi (1987)].The modelsdiffer in the predictedrelationship between mouth- (ATRHuman Information Processing Res. Labs., 2-2 Hikaridai,Seiko-the, piecepressure and lip displacement.To investigatethis, Yoshikawa mea- Kyoto619-02, Japan) suredthe phase relationship between mouthpiece pressure and lip strainas indicatedby a bileill•.U•e tapedto theupper lip [5. Acoust.See. Am. 97, Due to the difficulty in treatingjet beharlot, a generalagreement on the 1929-1939 (19925)].However, the relationshipbetween strain and dis- soundproduction of flueinstruments has not yet been obtained. This paper placementhave not beenexperimentally established, and Yoshikawa's as- discussesthree jet deflectionmodels proposed by severalauthors by means sumedcorrespondence "is still a hypothesiswhich needs refinement" (p. of the time-domainapproach. Simulations of an organflue pipe where the 1931).Optical measurements are required.Synchronized optical and blowingpressure is changedas a parameterare cardedout. These models acoustical measurementsof a trombonist's embouchure have been made in commonprovide oscillations in the fundamentalpipe resonancemode underperformance conditions, using an adaptation of techniquesdescribed and in the highermodes (overblows). They alsoprovide the underblow in Sercarzet al. [Am.J. Otolaryngol.13, 40-44 (1992)].Using strobed regimesof oscillationwhen the blowingpressure is lower. Differences videoscopy,individual video fields are coordinated with mouthpiecepres- amongthe modelsappear in the numberof the underblowregimes and in sureby meansof timingsignals. The phaserelationship between mouth- the levelsof harmonicsof oscillations.Transition among the oscillation piecepressure and lip displacementwill bereported for a varietyof fun- modeswould alsobe a clue to comparethe models.The resultsshould he damentel frequenciesand intensities.In addition, estimateswill be comparedwith an experiment of theartificial blowing of a pipein thewide presentedof theaperture area and the mouthpiece volume swept out by the rangeof blowingpressure, which is in progress. lips.
2456 d.Acoust. Sec. Am., Vol. 99, No. 4, Pt.2, Apdl1996 131stMeeting: Acoustical Sociely of America 2456
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 MONDAY AFTERNOON, 13 MAY 1996 MT. RUSHMORE, 1:00 TO 4:00 P.M.
SessionlpSC
SpeechCommunication: Informal Workshopon VoicePerception II
David B. Pisoni, Cochair SpeechResearch Laboratory, Department of Psychology,Indiana University, Bloomington, Indiana 47405
Jody Kreiman, Cochair Universityof California,Los Angeles, Head/Neck Surgery, 31-24 Rehab,Los Angeles, California 90024-1794
Thegoal of thisinformal workshop, a continuation of SessionIASC, is to bringtogether several researchers working on various aspectsof voiceperception. Historically, the study of voicehas been treated as a more-or-lessautonomous area quite distinct from otherresearch problems in speechand hearing sciences. In thisworkshop, some of thetraditional problems of voiceclassification and perceptionwill bediscussed and reviewed and then these efforts will berelated to recentfindings in speechperception and spoken wordrecognition which have shown important dependencies between traditional voice parameters and perceptual analysis of the spe•:hsignal. The contributors to the session include: Iody Kreiman, Diana VanLancker, Keith Johnson. Robert Remez, Peter Jusczyk, andDavid Pisoni. Please bring your slides and overheads and join in thediscussion on somelong-standing problems related to the "indexical"and "linguistic" functions of speech.For further information about this informal workshop, please feel free to contactD. B. Pisonivia E-mail: [email protected]. Everyone with an interest in speechperception, production, and spoken language processing is welcometo attendand contribute to the discussionof theseproblems.
MONDAY EVENING, 13 MAY 1996 MT. RUSHMORE, 7:00 TO 9:00 P.M.
Session leID
Interdisciplinary:Tutorial Lecture on Pitch, Periodicityand the Brain
Kenneth E. Gilbert, Chair AppliedResearch Laboratory, Pennsylvania State University, P.O. Box 30, StateCollege, Pennsylvania 16804
Chair's Introduction---7:00
Invited Paper
7:05
leID1. Pitch,periodicity, and the brain. WilliamM. Hartmann (Phys.Dept., Michigan State Univ., East Lansing, MI 48824)
The perceptionof pitchforms the basisof musicalmelody and harmony. It is alsothe mostprecise of all our humansenses. With imagination,this precision can be usedexperimentally to investigatethe functioningof the auditorysystem. The Indianapolistutorial will presentauditory demonstrations from the zoo of pitcheffects: pitch shifts, noise pitch. virtual pitch, dichotic pitch. and the pitches of thingsthat are not there at all.The tutorial will introducemodels of auditoryprocessing, derived from contemporary psychoacoustics andauditory physiology, and will testthese models against the experimentaleffects. It will concludeby describingthe criticalrole playedby pitch in the humanability to disentangleoverlapping voices. as modeledby currentwork on artificialintelligence.
2457 J. Acoust.Scc. Am., VoL 99, No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society of America 2457
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, 14 MAY 1996 MT. RUSHMORE, 8:30 TO 11:50 A.M.
Session 2aAA
Architectural Acoustics:Research in Chair and Audience Absorption
Dana L. Kirkegaard,Chair KirkegaardAcoustics. Inc., 4927 WallbankAvenue, Downers Grove, Illinois 60515
Chair's Introduction---8:30
Invited Papers
8:40
2aAAI. Sound absorptionby sea•sin concert halls, occupiedand unoccupied,and average sound absorptionby the interior surfacesof halls. Leo L. Betarick (975 MemorialDr., Ste. 804, Cambridge,MA 02138)
'Averagesound absorption coefficients were determinedfor the interiorsurfaces of concerthalls based on measurementsin five hallsin whichall finisheshad been completed before installation of seats.Fifteen halls were selectedfor detailedanalysis and divided intothree groups with seats that are (1) lightlyupholstered, (2) mediumupholstered, and (3) heavilyupholstered. Assurrdng relative humiditesof 50% for unoccupiedand 70% for occupiedhalls, "acoustical" areas (added 0.5-m edge effect) for seatingblocks, and the above,average interior-surface, absorption coefficients, the soundabsorption coefficients for occupiedand unoccupiedseats were calculatedfrom reverberationmeasurements. Among the three groups,it is tbund that there are large differencesin absorption coefficientsfor theseats at all frequencies,but particularly at low frequencies.The valuesare markedlydifferent from those previously published[L. Beranek,J. Acoust.Soc. Am. 92, 1-39 (1992)].Where possible, photos and visual analyses of thechairs are made to comparewith the data.
9:05
2aAA2. Sound absorption of occupied chairs as a function of chair design and audience clothing. Dana L. Kirkegaard (KirkegaardAcoustics. 4927 WallbankAve., DownersGrove, IL 60515)
In 1989,a seriesof experimentswas initiated at RiverbankAcoustical Laboratories to studythe detailed relationships between chair designand audienceabsorption. Chairs were measuredoccupied and unoccupied.Many chairs were disassemblerand testedas individualchair components to confirmspecific correlations between design and data. Chair manuthcturers responsed by redesigning chairsfor furthertesting. Each series of testswas designedto minimizethe numberof experimentalvariables. An unupbolstered referencechair provided a baselinefor eachseries of occupiedtests. The baselinemeasurements provide a meansof comparing occupiedchair measurements made with different occupants and/or changes of clothing.They also establish baseline absorption values for an audiencein minimallyabsorptive chairs. Results of theseoccupied chair measurements show that differences in chairdesign are mosthighly correlated with databelow 500 Hz, whichranged from 2 to 8 Sabins/person.Above 500 Hz, data rangedfrom 6 to i l Sabins/personas a functionof chair designand seasonalchanges in occupants'clothing. Results support the hypothesisthat chair designand seasonal clothing are critical in concerthalls and other rooms with low residualabsorption. [Research supported by Irwin Seating,JG Seatingand Country Roads.]
9:30
2aAA3. An overviewof the acousticaleffects of an audience. J.S. Bradley (Acoust.Lab., Natl. Res.Council, Ottawa K1A 0R6, Canada)
This paperreviews the variouseffects of an audienceon the acousticalproperties of an auditorium.At the mostbasic level, the total soundabsorption of bothoccupied and unoccupiedchairs can be predictedin termsof the perimeter/arearatio of audienceseating blocks.Using this technique,reverberation chamber measurements of occupiedchairs can be usedto estimatethe reverberationtimes of fullyoccupied halls. This technique has been extended to provideestimates of typicalsound-absorbing properties of occupiedchairs for all sizesof seatingblocks. Partially occupied seating areas present further problems. Audience effects on early-and late-arriving soundlevels and early/late sound ratios are related to the geometryof the hallsas well as to changesin the totalsound absorption. Interauralcross correlations and lateral energy fractions are not greatly influenced by thepresence of anaudience. Changes to themore detailedspectra of the directand early arrivingsound show that the effectof the audienceon the seatdip attenuationcan vary with the type of seatingas well as otherproperties of the hall.
9:55
2aAA4.Under-seat sound absorption for stadium/arenachairs. RobertC. Coffeen (CoffeenFricke & Assoc.,14873 W. 9thSt., Lenexa,KS 66215and Programs in ArchitecturalEng., Marvin Hall, Univ.of Kansas,Lawrence, KS 66045) For largeaudience spaces such as arenasand stadiums, it is oftendifficult to satisfactorilycontrol the unoccupied reverberation periodof thespace because of thelarge volume in relationto thearea of surfacesthat are available for the practicalinstallation of sound-absorbingmaterial; and whenchairs are of the plastic"stadium chair" type,it may be impossibleto achievea suitable stabilizationof the reverberationperiod between unoccupied and occupiedconditions. Of course,the use of chairswith sound absorbingupholstery is of majorbenefit in resolvingthese problems, but it is frequentlyfound that "hard"chairs are selectedfor maintenanceand cost reasons, and in spiteof resultingacoustical conditions. However, this situation can be at leastpartially remedied
2458 J. Acoust.Soc. Am., VoL 99, No.4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2458
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 by installingsound-absorbing material beneath each chair seatas an integralpart of the chair construction.Laboratory sound absorptiondata, obtained in associationwith a majorchair manufacturer, and field data obtained for a multipurposearena indicate that thisis a usefultechnique which can be appliedwhen "hard" chairs are to be usedfor reasonsnot relating to acoustics.
10:20-10:35 Break
ContributedPapers
10:35 frequencyrange by the openingand closingof holesof the resonator. 2aAAS. The resonatorsystem of controllingthe reverberationtime Becauseof the achievementof the variablesystem of soundabsorption of in an existinghall. ShigeoHase (TheatreDesign Co., Ltd., 1-16-1 theactual chairs, an experimenton soundabsorption power characteristics Shibata,Kita-ku, Osaka, 530 Japan)and YoshihitoKobayashi (Asahi was madein the reverberationroom of the chair with resonatorsgiven a GlassSound Proof System Co., Ltd., Tokyo, l10 Japan) variablewith the quantityand the diameterof holes,a neck'slength, and a cavity volumeof the seat.The resultwas obtainedthat variablecharac- In thispaper, the resonatorsystem of controllingthe reverberationtime teristicsof the soundabsorption power of the chairswith the resonator is examinedin an existinghall with 500 seatsand the room volumeof (four holes,30 mm diameterof the hole,and necklength 10 mm) is 0.2 4160m 3. Thecavity of eachchair with the volume of 0.012m 3 was m2 each for 125or 250 Hz bychanging the cavity volume of theseat in the utilized as a resonator. Four holes of a 30-mm diameter in the lower board experiment.The characteristicsunder the occupancycondition are nearly of chairscan be openedor closedby a sliding plate. By use of sucha equalto it undernonoccupancy conditions. systemof chairs,the reverberationtime at the low-frequencyrange in the hall could be controlled as: at 100 Hz: 1.93-1.58 s; at 125 Hz: 1.69-1.44 11:05 s; at 160 Hz: 1.54-1.36 s, and at 200 Hz: 1.52-1.45 s. 2aAA7. Partially coupled chambersin auditorium design. Russell 10:50 Johnson (Artec Consultants,Inc., 114 W. 26 St., 9 Fl., New York, NY 10001) 2aAA6. Examination of a resonator system for sound power absorption by hall chairs in the low-frequencyrange. Yoshihito Our consultinggroup has completed 12 concertrooms or operahouses Kobayashi (Asahi GlassSound Proof SystemCo., Ltd., 1-13-3 Ueno, with controllablepartially coupled chambers, and we have threeeither Taito-ku,Tokyo, l l0 Japan)and Shigeo Hase (TheatreDesign Co., Ltd., underconstruction or on the draftingboards. This paperprovides a very Osaka,530 Japan) brief overviewof this approachto auditoriumdesign and gives a rough ideaof how thisdesign feature might evolve during the next5 years,with For the purposeof controllingreverberation time in the low-frequency somereference to adjustabilityof the cubicvolume of the primarycham- rangein a room,the variablesystem of soundabsorption power by the ber, and to the locationof the openingsinto the secondarychamber. chairsin the low-frequencyrange by theexperiments in a scalemodel was examined.As the resultsof scalemodel experiments (1/10 scale)in the reverberationroom, the absorptionpower was controlledin the low- 11:20-11:50 PANEL DISCUSSION
TUESDAY MORNING, 14 MAY 1996 CELEBRATION B, 8:30 TO 11:05 A.M.
Session 2aEA
EngineeringAcoustics, Noise and StructuralAcoustics and Vibration:Noise Control in Internal CombustionEngines
Ahmet Selamet, Cochair Departmentof MechanicalEngineering and The Center for AutomotiveResearch, The Ohio State University, 206 West 18th Avenue, Columbus, Ohio 43210-1107
RaymondA. Kach,Cochair PowertrainOperations, Ford Motor Company, 21500 Oakwood Boulevard, POEE Building, Dearborn, Michigan 48121
Chair's Introduction--8:30
Invited Papers
8:35
2aEA1.A newmethodology of applyingmeasured acceleration and forcesor pressuresas excitationon powertrainmodels fornoise prediction. NickolasVlahopoulos, RichardD. StarkllI, and Walter Kargus IV (AutomatedAnal. Corp., 2805 S. Industrial, Ste. 100, Ann Arbor, Ml 48104-6767) Numericalmethods can be used to computethe vibration of powertrainsystems or componentsand the corresponding radiated noise.Specifically, the finite-element method can be utilizedin computingthe structural vibration. The structural response will constitutetheboundary conditions forthe boundary-element method incomputing the radiated noise. In thiswork a newmethodology ispresented, itallows acombination ofmeasured accelerations, andforces or pressures, toapply as excitation. The innovative elements
2459 J. Acoust.Soc. Am., Vol. 99, No.4, Pt.2, April1996 131stMeeting: Acoustical Society of America 2459
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 thiswork are: (i) the methodologyutilized in prescribingthe acceleration at certainparts of thestructure; and (ii) integratingthe vibrationanalysis within the acousticssoftware and creating a singleprocess for computingthe noise.A genericsix-cylinder engine modelis usedas an exampleto demonstratethe newcapabilities. The structuralfinite-element model is utilizedto computethe modal basisof the structure.Acceleration measured at the bearinglocations, and pressureloads applied at the cylinderhead (simulating combustion)comprise the excitation.The modalbasis of the structure,the loads,the structuralmodel, and the acousticboundary- elementmodel are utilized within the acousticssoftware in comparingthe structuralvibration and the correspondingradiated noise.
9:00
2aEA2. Sound-pressuresimulations on a concentrictube resonator. MehmetS. Ciray (ArvinNorth American Automotive, 1531 13th St., Columbus,lN 47201)
A concentrictube resonator was investigatedto determinethe accuracyof the numericalmethod used for sound-pressuresimu- lations.The interactionbetween the tube and the cavity was througha perforatedsurface, of which the acousticalproperties were experimentallydetermined [1. W. Sullivan,I. Acoust.Soc. Am. 76, 479-484 (1984)].These properties were imposed as boundary conditionsto the finite-elementanalysis (FEA) code.Predicted and measured transmission losses were compared under no meanflow conditions.The work was then extendedto includethe effectsof mean flow. Empiricalequations given in literaturewere usedto modifythe acoustical properties of theperforated surface to incorporatethe effects of flow[Garrison et al., Prattand Whitney Aircraft Rep.(1969)]. The meanflow terms in thescalar Helmholtz equation were treated explicitly in orderto avoidthe additional storage requirementsfor thelEA code.Special attention had been paid to thedesign of theFEA code,such that information can be searnlessly exchangedwith a computationalfluid dynamics (CFD) simulation,for possiblefuture research.
9:25
2aEA3.Computational modeling of multiple-passperforated tube silencers in the time domain. N.S. Dickey (Dept.of Mech. Eng.,Univ. of Michigan,Ann Arbor,MI 48109-2121)and A. Selamet (OhioState Univ., Columbus, OH 43210-1107)
To reducethe low-frequency radiated noise from automotive engines, intake and exhaust system silencers often employ perforated tubeelements. These geometries commonly consist of one or moreperforated tubes aligned axially within an externalduct having a lengthsignificantly larger than any crossdimension. For sucha silencer,the low-frequency acoustic performance may be analyzedby consideringone-dimensional flow in eachof the passages,coupled by the communicationbetween regions through the perforate interface.The behaviorof theseconfigurations depends on numerousparameters, including porosity, orifice dimensions, mean and oscillatingthrough flow and grazingflow levels,in additionto the overallgeometry. In automotiveapplications, nonlinear orifice behaviormay he expected.The presentstudy applies a timedomain fluid dynamic model to predicttransmission loss of perforatedtube elements.Since the Navier-Stokesequation is retainedin nonlinearform, the techniqueshows promise for applicationto the breathing systemsof firingengines. where numerous nonlinearities affect the validity of frequencydomain analyses. Multiple-pass silencers with zero mean flow are modeledwithin an extendedimpedance tube configuration.The effects of overall geometry,porosity, and sound-pressurelevel are studied and limitations of theone-dimensional assumption are addressed.[Work supported by FordMotor Co.]
9:50-10:05 Break
ContributedPapers
10:05 length,and (2) the additionof an areaexpansion in the sidebranch are investigatedto modifythe acousticresonance characteristics. [Work sup- 2aEA4. Predictive acoustic modeling applied to the control of portedby FordMotor Co.] intake/exhaust noise of internal combustion engines. Peter O. A. L. Davies (Inst. of Sound and Vib. Res., Univ. of Southampton, SouthamptonSO17 1BJ,UK) 10:35 The applicationof validatedacoustic models to intake/exhaustsystem acousticdesign is describedwith referenceto a sequenceof specificprac- 2aEA6. Internal combustionengine noise analysis and production tical examples.These includelarge turbochargeddiesel generatingsets, using a novel multipulse excited time series modeling technique. truck engines,and high-performancepetrol engines. ScottA. Amman (FordMotor Co., 3003 Prairie,Royal Oak, M1 48073) and ManoharDas (OaklandUniv., Rochester,MI 48309-4401)
Automobile manufacturers have learned that customers have well- definednotions as to what an automobileengine should sound like for the varlou•vehicle segments (luxury, sportsear, economy, etc.). Therefore, it is 10:20 advantageousto modeland synthesizevarious types of enginesounds for 2aEA5. Side branches in automotive intake systems as noise customerevaluation. Much work has been done in the area of speech generators. A. Selamet (Dept. of Mech. Eng. and Ctr. for Automotive modelingand synthesisbased on physicalassumptions of humanspeech Res.,Ohio StateUniv., 206 W. 18thAve., Columbus,OH 43210-1107)and production.The intentof this paperis twofold. First discussedare the P.M. Redarich (Univ. of Michigan,Ann Arbor,MI 48109-2121) similaritiesand differences between speech and engine noise modeling and synthesisproblems. Second, application of techniqueslearned for speech It is well establishedthat the couplingof flow inducedvortices and synthesisto that of automotivenoise production is demonstrated.Early acousticresonances in a closedside branch can leadto theproduction of modelsof speechproduction used periodic pulse excitation in a linear bothlarge wave amplitudes in titis ductand excessivenoise levels in the predictivecoding (LPC) framework.This technique is usedto synthesize mainduct. The presentstudy concentrates on the propagationof noisein enginenoise. It is thencompared to thatof a new suboptimalmultipulse an automotiveintake systeminduced by the closed side branchof an methodproposed by the authors.It is hopedthat this paper will pavethe exhaustgas recirculationtube. The effectsof (1) alteringthe side branch pathfor a hetterunderstanding of the relationship between the two systems
2460 d. Acoust.Soc. Am., VoL 99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2460
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 sothat much of thework performed in speechanalysis and production can One of the featuresof the active intensitycontrol strategyis that the be appliedto the analysisand synthesis of automotiveinternal combustion controlperformance can be maintainedregardless of the sensorlocation, enginesounds. comparedwith the conventional local sound-pressure control methods at either interiordownstream or exteriorfield position.Simple numerical 10:50 examplesare demonstrated to compare the acoustic characteristics of the active intensitycontrol scheme with the othercontrol strategies. For a 2aEA7. Active control of sound radiated from an open-ended duct morepractical comparison with the conventionalsound-pressure control usingsound intensity. S.-W. Kangand Y.-H. Kim (Ctr. for NOVIC, strategy,an experiment,based on a time-domainadaptive filtering with an Dept. of Mech. Eng., KAIST, ScienceTown, Taejon 305-701, Korea) intensitysensor filtered-x LMP (least-mean-product)algorithm, is per- Soundintensity based active control for the reductionof soundradiated formed.From the experimentalresults, it is shownthat the exteriorsound out of the ductexit is studiedexperimentally as well as theoretically.The field is much more observableby sensingthe active intensitythan by activeintensity control strategy is derivedbased on the relationof the sensingthe sound pressure. It is alsodemonstrated that the active intensity exterior sound field out of the duct exit and interior sound field of the duct. controlperformances are superior to the sound-pressurecontrol ones.
TUESDAY MORNING, 14 MAY 1996 HARRISON'S, 8:00 TO 11:50 A.M.
Session 2aMU
Musical Acoustics: Reed Instruments: Research and Performance
JamesM. Pyne,Chair Schoolof Musicand Center for CognitiveScience, The Ohio State University, 1866 College Road, Columbus, Ohio 43210
Invited Papers
8:00
2aMUI. Acousticsof Americanreed organs. .lamesP. Cottingham (Phys. Dept., Coe College, Cedar Rapids, IA 52402) The instrumentthat hascome to be calledthe "American"reed organ shares with its relativesthe accordion,concertina, and harmonicathe useof freereeds, but differs from its reedorgan cousin, the harmonium,in the useof a vacuumexhauster rather than a pressurebellows to drivethe reed vibration. The acoustical properties of theinstrument are summarized along with the results of somerecent experimental studies. These investigations have explored variations in propertiesof boththe reedvibration and the resultingsound as a functionof pressure.Effects of airflowrate, and reed cell dimensions have also been studied. Both live and recordedmusical examples are provided.
8:30
2aMU2. Music for the reed organ. EdwardA. Peterson(Reed Organ Society Bulletin, 101 Ulen Blvd., CountryClub Park, Lebanon,IN 46052-3202) Membersof theAmerican Guild of Organistsand the Reed Organ Society will performon instmmentsfrom the Indianapolis area. Selectionswill be presentedwhich illustrate the musical range of thereed organ. Commentary on theprinciples of operationof the instrumentand playing techniques will be provided.
9:00
2aMU3."Reed all aboutit:" The giantgrass that providesreed cane for musicalinstruments. Marcus Eley (RicoIntl., 8484 SanFernando Rd., SunValley, CA 91352) Canereeds for musicalinstruments are madefrom the stalksof amndodonax, a giantgrass. Although arundo donax grows wild througoutthe world only certain conditions of soiland climate will producecane that is suitablefor musicmaking. The controlled conditionsof plantationgrowth, as in theplantation system used by RicoInternational, are proving to be successfulin growingcane thatis moreconsistently of high quality. Nurturing and careful harvesting bring the mature stalks to thestage where they can be carefullysun-dried in racksfor many months and finally cut, between nodes, into tubes. The cane tubes are then shipped to SunValley for themanufacture of musicalinstrument reeds, a processthat involves special tooling and unique manufacturing techniques.
9:30
2aMU4.Techniques for deftnineclarinet reed quality via coml•uterizedlight transmission analysis. James M. Payne(School of Musicand Ctr. for Cognit.Sci., Ohio State Univ., 1866 College Rd., Columbus, OH 43210) A basicand well-recognized problem in clarinetand saxophone (single-reed) performance is maintainingconsistency in high- qualitygeneration and manipulation of tones. This generative process, involving reed, mouthpiece, and the player's embouchure, producesthe instrumental "voice" of theperformer and is fundamentalto artistic communication. Playing skill and a well-designed mouthpiececannot overcome the liability of poorlyvibrating arundo donax, the natural material used in reedmanufacture. lnconsis-
2461 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2461
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 tencyin qualityleads professionals to spend as much as $2500 per year on reedsand to performon relativelyfew of thosepurchased. Highly skilledperformers agree that the identificationof fineperformance reeds cannot be accomplishedby visualinspection. Trial by playingis the customarymeans of determiningquality and one mustpurchase reeds before these trials can be made.Even these carefullyselected reeds degrade and b•come unplayable after approximately 10-20 h of performance.Computerized light transmission analysis(TRACOR) has proven to be of valuein determiningperformance characterisdcs of clarinet reeds.
10:00-10:15 Break
ContributedPapers
10:15 canerather than by the addedwater mass.Plots are presentedcomparing the dependenceof flexuralwave fundamental frequency on moisturefor 2aMUS. Observedvibration patterns of clarinet reeds. P. L. Hoekje differenttypes of canereeds. The resultsindicate that the fundamental andG. MatthewRoberts (Dept.of Phys.,Univ. of N. Iowa, CedarFalls, IA 50614-0150) frequencyof a canereed may decrease by as muchas 30% as it becomes saturatedwith water.The flexuralrigidity diminisheswhen the cane is It hasbeen shown that a resonanceof thereed contributes significantly moistened.The findingsare importantfor the characterizationand evalu- to theplaying behavior of thesingle-reed woodwind [S.C. Thompson,I. ation of reedswhere hidden uncontrolled trapped moisture significantly Aconst.Soc. Am. 66, 1299-1307(1979)]. As anextended object, the reed affect the response,vibration, and stiffnessof the reed. is actuallyexpected to possessmany resonances, and thesehave been predictedin FEA calculations[D. Casadonte,J. Acoust.Sac. Am. 94, 1807(A)(1993)] and observed in vibrationspectra of isolatedreeds [D. H. Kecfeand S. Wasfiler,J. Acoust.Sac. Am. 94, 1833-1834(A) ( 1993)].The currentstudy used holographic interferometry to identify the vibration patternsof a clarinet reed mountedon a mouthpiece,as driven by an 10:45 acousticfield internalto the mouthpiece.Without a player's lips to shorten the vibratingsection, the lowestfrequency and mosteasily driven reso- 2aMU7. Handmaking clarinet reeds: New tools accelerate the nanceis in theregion 1500 to 2000 Hz andconesponds to thelowest mode process. TimothyAnderson (Schoolof Music,Ohio StateUniv., 1866 of a rod clampedat one end. The secondand third resonancesare near CollegeRd., Columbus,OH 43210) 4000 Hz. The secondmode displays twisting motion, but with a surprising degreeof asymmetry,while the thirdmode is similarto the secondmode The vast majorityof clarinetismworldwide (professionals, students, of a rod clampedat one end. andamateurs) perform on commerciallymanufactured reeds. However, a numberof performers,including many professionals,maintain that com- 10:30 mercialreeds can never matchthe high quality of reedshandmade from 2aMU6. Effect of moisture on flexural wave fundamental frequency tubeby the performer.For clarinetiststhis time-consumingpractice was of clamped-endcane reeds. JacquesR. Chamuel (SohoquestAdv. oncestandard procedure and still is withdouble-reed performers (oboe and Ultrason.Res., P.O. Box 81153,Wellesley Hills, MA 02181-0001) bassoon).This reed-makersupports the positionthat the best reedsare Experimentalresults are presented demonstrating the effect of moisture producedby the performer.Recently, tools have becomeavailable that on the fundamentalflexural wave frequencyof clamped-endcane reeds. acceleratethe processof makingone's own clarinetreeds. Using some of The flexuralwave velocitydecreases as the moisturelevel increases.The thesetools a reed will be fashionedfrom arundodonax tube duringthe changein flexuralwave velocity seems to be dominatedby softeningof the presentationand its soundwill be demonstrated.
11:00-11:15 Break
Invited Paper
11:05
2aMUS.! Clarinetti18rtuosi: Chamber ensemble of the Ohio StateUniversity. JamesPyne and Elisabeth Stimpert (Schoolof Music,Ohio StateUniv., 1866College Rd., Columbus,OH 43210)
The clarinetensemble continues to emergeas a capablevehicle for art performance.It can, morethan any otherfamily of wind or br,•s instruments,closely rep•'•luee the ranse, flexibility, and homog¸n•ity of th• atringons•mble. These characteristicswill be brieflydiscussed and demonstrated using the individual instruments of theclarinet family from contra-bass to piccoloclarinet including bassethorn, a favorite instrumentof Mozart. ! Clarinerti Virtuosi are clarinet performancemajors at The Ohio State University, graduatestudents and undergraduate seniors. They will performa varietyof worksthat display the wide range of musicaland virtuosic capabilityof the ensemble.
2462 J. Acoust.Soc. Am., VoL 99, No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society of Amedca 2462
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, 14 MAY 1996 CELEBRATION A, 8:30 TO 11:30 A.M.
Session 2aNS
Noise: Hearing ConservationIssues from a Global Perspective
Larry H. Royster,Chair Mechanical and AerospaceEngineering Department, North Carolina State University,Raleigh, North Carolina 27695-7910
Chair's Introduction4:30
Invited Papers
8:35
2aNS1.Noise and hearingconservation regulations throughout the world. Alice H. Suter (Alice Suterand Assoc., 575 Dogwood Way,Ashland, OR 97520)
The adventof electroniccommunication enables professionals in noise and hearing conservation to communicatemore effectively thanever beforewith their colleaguesin othernations. This fact, addedto the harmonizationof noisestandards by the European community,enables people to watchthe developmentof trendsthroughout the world.The trendin nations'noise standards is toward the3-dB (equal-energy) role, toward A-weighted permissible exposure limits below 90 dB, andtoward more specific requirements for audiometrictesting and the wearingof hearingprotection devices. In additionto protectingworkers against hearing loss, several nationsinclude requirements to protectagainst other adverse effects of noise.Some nations have issued noise standards for specific workplaces,processes, and equipment. Enforcement of noisestandards varies considerably among nations, with somenations viewing noisestandards merely as recommendations,and othersenforcing them seriously.
9:00
2aNS2. Variousinternational approaches for evaluatingimpulse noise. Daniel L. Johnson (Biophys.Operation, EG&G MSI, 2450 Alamo SE, P.O. Box 9100, Albuquerque,NM 87119)
For impulseswith a peak sound-pressurelevel (SPL) under140 dB, 1SOI999provides a standardizedapproach using total A-weighledenergy. Some countries may use a smallcorrection factor in addition.At the presenttime, most approaches for evaluating impulsenoise above 140 dB usethe peak sound-pressure level and some estimate of durationof thewaveform. There is norecognized standardmethod for evaluatingsuch impulses. Furthermore, the problemwith thispeak and duration method is thatsome waveforms with the samepeak and duration parameters are far morehazardous than others. As will be discussed,each major country is usinga slightlydifferent approach. However, there is a NATO workinggroup investigating a common approach. A partof thisapproach may be to usesome type of weightedenergy.
9:25
2aNS3. International activitiesin the use,standardization, and regulationof hearing protection. Elliott H. Berger (E-A-R/ CabotSafety Corp., 7911 Zionsville Rd., Indianapolis,IN 46268-1657) Preventionof hearingloss due to noiseexposure often means one thing--the consistent and correct use of hearingprolection. Since noir-inducedhearing loss has been identified as one of the leadingoccupational diseases and injuries, there arc millionsof workers worldwidein needof, or alreadycurrently wearing, hearing protection. How well they utilizethe products they are provided, as well as the extentand quality of governmentenforcement activities, is influenced,in part,by the standardsand regulations that govern the testingand labelingof suchproducts. As such,this paperwill summarizecurrent international standards on testing,labeling, and performanceof hearingprotectors as well as reviewing field performance and anecdotal observations pertaining to actualuse. Attention will focuson [SO, CEN (Communityon EuropeanNormalization), and Australian activities, as well as on a newdraft ANSI standard (S12.6-199X)pertaining to the laboratorymeasurement of the real-earattenuation of hearingprotectors, and on the effortsof the NationalHearing Conservation Association Task Force on hearingprotector effectiveness to craftrecommendations for the labeling of hearingprotection devices sold in the IJ.S.
9:50
2aNS4. The audiometricphase of the bearing conservationprogram: Summary of activitiesfrom a global standpoint. LarryH.Royster (MAEDept.,N.C. StateUniv., Raleigh, NC27695-7910)andJuliaDoswellRoy•ter (Environ. NoiseConsultanls, Raleigh,NC 27622-0698) As partof the activitiesof ISO/'I'C43/XVG5: Evaluating the effectivenessof hearingconservation programs, a questionnairewas mailedout to the interestedInternational Standards Organizations membership requesting information related to hearingconservation programactivities. Part of this questionnairedealt with the audiometricactivities in eachcountry. This paperwill summarizethe findingsfrom thissurvey and discussthe pastand presentactivities of ISO/TC 437vVGS.The significantdifferences that exist in the attitudetoward obtaining and makinguse of audiometricdata aroundthe world will be discussed.
2463 J. Acoust. Soc. Am., Vol. 99, No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society of America 2463
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 10:15-10:30 Break
ContributedPapers
!0:•0 11:oo
2aNS5, Repeatability and reproducibility in hearing protector 2aNS7. Modeling auditory hazard from impulses with large testing. JohnR. Franks,William J. Murphy (Bioacoust.and Occup. Vib. low-frequencycomponents. G. RichardPrice and Joel T. Kalb (Human Sec.,Natl. Inst.for Occup.Safety and Health, MS C-27, 4676 Columbia Res. and Eng. Directorate,Army Res. Lab., AberdeenProving Ground, Pkwy.,Cincinnati, OH 45226-1998),and Stephen D. Simon (Natl. Inst. MD 21005-5425) for Occup.Safety and Health, Cincinnati, OH 45226-1998) Earlierresearch [Royster et al., J. Acoust.Soc. Am. 99, 1506-1526 In orderto validatethe modelof hearinghazard from intensesounds (1996)]has reported on a newlaboratory test method to predictthe amount [G. R. Price and J. T. Kalb, J. Acoust.Soc. Am. 90, 219-227 (1991)], of attenuationhearing protectors provide to workersin thereal world.The hearingloss data havebeen sought from impulsenoise exposures which subjectfit method(SF) employsthe useof subjectswho are audiometri- extendthe rangeof exposuresalready examined with the model.One such cally competentbut naivewith respectto hearingprotector use and who impulse(reported in Priceet al. at thismeeting) is thatproduced by air bag must rely only uponthe manufacturer'sinstructions to fit a protectorfor deployment,which containsa mixtureof high-frequencyenergy often su- testing.One unresolvedissue has been the numberof subjectsand number perimposedon a low-frequencypedestal, reaching peak pressures near 170 of repeatedtests per subjectnecessary to achievethe desiredlevels of dB and with B durationsof 150 ms.The model'spredictions for firearms repeatability(test-retest within a laboratory)and reprodueibility (test- impulsesin the sameintensity region correlated well with actualthreshold retestbetween laboratories). Attenuation data from four laboratoriescol- shifts[Price eta!., J. Acoust.Soe. Am. 97, 3343 (1995)];however, the lectedwith the sameprotocol showed that estimatesof variancefor the hazardscalculated with the air bag impulseswere generallytoo large. reproducibilityacross hearing protectors (Bilsom Muff, E-A-R plug, Examinationof the datasuggested that middle-ear muscle activity needs to EPI00 plug,¾-51R plug) for informeduser fit {ILIF) were greaterthan be accountedfor, that correctionsfor the angle of incidenceof the wave- estimatesof the SF variance.The estimatesof variancefor the repeatability front are needed,and that the existingmodel included too muchdamping acrossprotectors and frequency were comparable between the IIJF andSF for large displacementsof the middleear. conditions.The averageIUF attenuationsacross protectors and frequency weregreater than the averageSF attenuationsfor all of the plugs.
10:45 11:15 2aNS6. Hearing hazard from the noiseof air bag deployment, G. RichardPrice (Human Res. and Eng. Directorate,Army Res. Lab., 2aNS8. Maximum safe exposure levels for intense reverberant AberdeenProving Ground, MD 21005-5425),Stephen W. Rouhana(GM impulses in an enclosure. JamesH. Patterson,Jr. (202 Cedar Chase, Res.Lab., Warren, MI 48090-9055),and Joel T. Kalb (ArmyRes. Lab., Dothan,AL 36303), Daniel L. Johnson,and JohnT. Yelverton (EG&G AberdeenProving Ground, MD 21005-5425) MSI, Albuquerque,NM 87119)
Recentstudies have questionedthe adequacyof currentnoise standards Studieswere undertakento determinethe maximumsafe-exposure lev- for intenseimpulses, especially those with large low-frequencycontent, a els in a reverberantwave environmentlike that producedby firing an categorywhich includesair bag deployments.Unfortunately, almost no antiarmorweapon from a smallroom. The approachwas first, to establish testshave been done with realears and air bagimpulses. Such data are also neededfor developmentof theoryand validation of ourhearing loss model a thresholdof injury for organsother than the ear then to determine [G. R. Priceand J. T. Kalb, I. Acoust.Soc. Am. 90, 219-227 (1991)]. whetherthese levels were safe for theear. Using sheep as an animalmodel, Therefore, 32 anesthetizedcats positionedat the driver and passenger the thresholdof nonauditoryinjury was found to be approximately190 dB locationsin a pickuptrack were exposedin pairs to one air bag deploy- peakSPL {65 kPa)with a B durationlonger than 200 msfor oneimpulse ment(electrically initiated). Hearing was tested at 1, 2, 4, 8, and 16kHz by andapproximately 187 dB peakSPL (46 kPa) for threeimpulses. Two evoked-responseaudiomerry before exposure, immediately after, I month, groupsof 40 animalswere usedto establishstatistical confidence in the and 6 monthslater. Exposureconditions included doors open, compart- "no injury levels." The auditoryeffects were investigatedusing human mentclosed, and closedcompartment sealed with tape;seven exposures to volunteersexposed to a progressionof levelsfrom 168 to 185 dB at the ear passengerbag only and nine to driver and passengerbags. Pressuresat for oneimpulse and then, to two andthree impulses at 183dB. A tempo- inboard ears rangedfrom 167- to 173-rib peak and B durationsfrom rarythreshold shift (Trs), determined2-4 min postexposure, was used as approximately50-150 ms, with unweightedenergies as high as 4000 J/ an indicatorof auditoryeffect. The volunteerswore an earmuffmodified to m2 (or8 h LEQ^=95.5 riB). All earsshowed significant hearing losses simulatea poor fit, duringthe exposures.No significantTFS in 59 volun- immediately,averaging 60-dB thresholdshift at 4.0 kHz whichresolved to teerswas observed,indicating no effectson hearingup to the maximum an averagePTS of 37 dB. safe-exposurelevels for otherorgans.
2464 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of Amedca 2464
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, 14 MAY 1996 REGENCY C, 8:30 TO 11:30 A.M.
Session 2aPAa
PhysicalAcoustics and Bioresponseto Vibration and to Ultrasound:Workshop on TherapeuticApplications of Medical Ultrasound I
Floyd Dunn, Chair BioacousticsResearch Laboratory, University of Illinois, 405 N. MathewsAvenue, Urbana, Illinois 61801
This Workshopis an attemptto bring a "small meeting"environmenl into a big meeting.In additionto the tutorialand special presentationsoutlined below and in thelater two sessions(2pPAa, 3aPAa), there will be significantparticipation by otherworkshop attendees;discussion among participants is a majorobjective of this program.Therefore, a specifictimetable will not be followed duringthe workshop.
Chair's Introduction--8:30
Invited Papers
2aPAal. Remotelyinduced shear acoustic waves in tissuesby radiation force of focusedultrasound. ArmenP. Sarvazyan {Dept.of Chemistry,Rutgers Univ., Piscataway,NJ 08855-0939)and Oleg V. Rudenko (MoscowState Univ., Moscow,Russia I 19899}
A new acousticapproach to medicalimaging and diagnostics based on the remoteevaluation of shearelasticity modulus of soft tissuesis considered.The new method,called shearwave elasticityimaging, is basedon the detectionof shearwaves remotely generatedin tissuesby radiationpressure of amplitude-modulatedfocused ultrasound. Remotely induced shear wave is fully attenuated withina sh•rl distanceand the inducedstrain in thetissue can be extremelylocalized. By choosingappropriate temporal characteristics of the amplitude-modulatedultrasonic pulse, the volumeof tissueinvolved in the mechanicalexcitation can be kept on the orderof 1=AO cm 3, in contrasttoother methods of elasticityimaging where the complete organ is subjectedtoshear stress. Consequently, evaluationof viseoelasticproperties of tissueis greatlysimplified since trivial boundaryconditions can be assumedand an infinite mediummodel can be usedto reconstructthe mechanicalproperlies of tissue.Analytical equations describing the radiationrome field inducedby nonlinearfocused ultrasound are derived and propagation of shearwaves generated in tissuesis considered.A possibility of deliberatelyexploiting the nonlineareffects to enhancethe radiationpressure in a smallarea near the focusof the beamis shown.
2aPAa2. Acousticnonlinearity and radiation pressurein ultrasonicbioeffects. Oleg V. Rndenko (Phys.Dept., MoscowState Univ.,Moscow, Russia 119899) and Armcn P. Sarvazyan(Rutgers Univ., Piscataway, NI 08855-0939)
Most of the biomedicalapplications of ultrasoundare basedon the useof focusedultrasound with a highconcentration of energy in thefocal region and, respectively, with significantcontribution of nonlinearphenomena in ultrasonicbioeffects. Tbe mainobjective of thecurrent paper is to providea clearunderstanding of basic phenomena in nonlinearacoustic fields oi' focused ultrasound, and to derivesimplified equations that would enable physicists and engineers to optimizeparameters of biomedicaldevices for particular applications.Special attention is paid to the contributionof acousticnonlinearity to the second-orderquantities, such as radiation pressureand temperature rise in ultrasonicfields in tissues.Based on asymptoticmethods recently developed in nonlinearacoustics, analyticalsolutions of theequations for the radiationforce induced in a dissipativemedium are considered. The relationshipsbetween parametersof acousticfield and characteristicsof biologicaltissues are quantilativelyanalyzed. Possible roles of nonlinearacoustic phenomenaand ultrasound radiation force in variousfeatures of interactionof ultrasonicwaves with biologicalmedia are discussed.
2aPAa3.Finite amplitudedistortion in derstingof ultrasoundfields. T. Christopherand E. L. Carstensen(Rochester Ctr. for Biomed. Ultrasound,Univ. of Rochester,Rochester, NY 14627)
All ultrasoundexposure indices that havebeen formulated up to the presenttime assumethat the propagationof ultrasoundis linear.In fact,under most exposure conditions for whichbiological effects may be a concern,sound propagation is highlynonlinear. A nonlinearpropagation model has been used to evaluatethe natureof the effectsthat occurunder realistic exposure conditions encounteredin diagnosticprocedures. Because of the way that the thermalindex is defined,it tums out that ignoringnonlinear propagationleads to underestimatesof tissue temperature increments that typically are less than 40%. As currentlyimplemented, the
2465 J. Acoust.Soc. Am., Vol.99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Sociely of America 2465
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 mechanicalindex may be underestimatedby morethan a thctorof 2 becauseit ignoresthe saturationof the soundfields that result from nonlinearpropagation. For largepropagation distances in softtissues (e.g., 10 cm at 3 MHz in liver),however, it is physicallydifficult to exceedtissue pressures corresponding to MI>2 becauseof thesesame saturation phenomena.
2aPAa4. Lung hemorrhagefrom exposureto ultrasound. Diane Dalecki, Sally Z. Child, Carol H. Raeman,David P. Penney, and Edwin L. Carstenscn(Rochester Ctr. for Biomed.Ultrasound, Univ. of Rochester,Rochester, NY 14627)
Thresholdsfor lunghemorrhage from exposureto pulsedultrasound have been determined in neonatalmice (24-36 h), juvenile mice(14 days),and adultmice (8-10 weeks),and neonatal (24-36 h) andyoung (10 days)swine. The thresholdat 2 MHz is approximately1 MPa and the thresholdincreases gradually with frequencyin the rangefrom 0.1 to 4 MHz. Positiveand negative pressurepulses are equallydamaging. Following exposure, suprathreshold lesions are not progressivewith time and are repairedby usualphysiological mechanisms. Although the uniquesensitivity of lung tissueto ultrasoundis associatedwith the presenceof air in the alveolae,this doesnot necessarilyimplicate acoustic cavitation as the responsiblemechanism. Thin sectionsof murinelung are moresensitive than thickerregions probably because of reducedreflection at the surfaceof the lung tissue.
2aPAaS. Effects of ultrasound on binding of tissue plasminogenactivator to fibrin. Farhah Sidiqi, Julie V. Braaten,and CharlesW. Francis (HematologyUnit, Dept. of Medicine,and RochesterCtr. for Biomed.Ultrasound, Univ. of Rochester,601 ElmwoodAve., Rochester,NY 14642)
To investigatethe mechanismof ultrasound-enhancedfibrinolysis, the effect of ultrasoundon binding of tissueplasminogen activator(t-PA) to fibrinwas examined because t-PA-fibrin interactionsare importantin determiningthe rateof fibrinolysis.A novel systemto quantiratet-PA-fibrin interactionswas developed in whichradiolabeled, active site blocked t-PA flowedthrough a fibrin gel at constantrate andtemperature, and specificbinding was determinedby monitoringincorporation of radiolabel.Exposure to I-MHz ultrasoundto 2 W cm2 resultedin nosignificant change in thekD of t-PAbinding to either cross-linked or noncross-linked fibrin.Ultrasound, however, significantly increased the Bm•, andthe molarbinding ratio increased in thepresence of ultrasoundfrom 1.85 (mol t-PA/mol fibrin)to 2.54 (tool t-PA/mol fibrin) for noneross-linkedfibrin and from 1.19 (mol t-PMmol fibrin) to 1.43 (mol t-PA/molfibrin) for cross-linkedfibrin. Ultrasound resulted in no significantchanges in bindingof t-PA to fibrinmonomer in thesame system.It is concludedthat exposure to ultrasoundincreases binding of t-PA to polymerizedfibrin, possibly by exposingadditional bindingsites in the polymerwhich are inaccessiblein the absenceof ultrasound.
2aPAa6. Acceleration of thrombolysis by ultrasound in two rabbit models. Charles W. Francis and Patrick N. Riggs (HematologyUnit, Depts.of Medicine and VascularSurgery, Univ. of Rochester,601 ElmwoodAve., Rochester,NY 14642)
Ultrasoundaccelerates fibrinolysis in vitroat intensitiesthat are potentially applicable clinically to enhancethrombolyti½ therapy. To extendthese findings/n vivo, the effectsof ultrasoundon fibrinolysisinduced by streptokinasehave been examined in two rabbit models.In a rabbitmodel of fibrinolysisin smallvessels, scalpel cuts were made in the ear andrabbits were then rested 2 h to allow maturationof hemostaticplugs. Bleeding occurred when clots in smallear vesselswere lysed during thrombolytic therapy. In a prospectivestudy, administration of streptokinasealone results in bleedingafter 18 ñ 3 min (mead_+ SEM}, but addition of ultrasound (1 MHz, 1 W cm-2 anda 50%duty cycle) shortened the time to bleedingto 7_+4min (p<0.05). Theeffect of ultrasoundwas also examinedin a rabbitarterial thrombolysis model and, thrombolysis occurred in 9/17 (53%)of animalsreceiving both streptokinase and ultrasound,and thiswas significantly greater than the rate in animalsreceiving streplokinase alone (2/15, 13%,p=0.025}. Light and electronmicroscopic examination revealed minor changes in plateletaccumulation on the thrumbusand minor changes in the vessel intimaof ultrasound-exposedvessels. These findings indicate that externallyapplied ultrasound accelerates fibrinolysis in vivo.
2aPAa7. Ultrasoundincreases fluid permeationin fibrin gels and reversiblydisaggregates large fibers. Julie V. Braaten, FarranSidiqi, Edwin L. Carstensen,and Charles W. Francis (HematologyUnit, Dept.of Medicine,and Rochester Ctr. for Biomed. Ultrasound, Univ. of Rochester, 601 Elmwood Ave., Rochester, NY 14642)
Sinceultrasound accelerates fibrinolysis and sincetransport of enzymesinto clots is an importantdeterminant of the rate of fibrinolysis,the effect of ultrasoundon fluid permeation through fibrin gels in vitrowas examined. Gels of purifiedfibrin were prepared in plastictubes, and the rate of pressure-mediatedfluid permeation was measured. Exposure to 1 MHz ultrasoundat 2 W cm-2 and dutycycle of 5 mson, 5 msoff resultedin a significant(p = 0.005) increasein flow throughthe gel of 29.0_+4.2% (mean--.SEM). The increasein flowwas intensity dependent and not due to heatingor fragmentationbut was reduced by degassing,suggesting a role for cavitation.Scanning electron microscopy was used to examinepotential effects of ultrasoundon fibrinstructure, which is theprimary determinantof flowresistance. Fibrin gels were fixed and prepared for microscopybefore, during, and after exposure to l-MHz ultrasoundatintensities from 4 to8 W cm-2. Ultrasoundcaused a significant (p<0.000001) increase infiber density and decrease in fiberdiameter which was reversible when ultrasound was switched off. These results indicate that ultrasound exposure can induce a significantreversible change in fibrinstructure and fluid permeation that could contribute tothe ultrasonic enhancement of fibdnolysis.
2466 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2466
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, 14 MAY 1996 CANYON HALL, 8:30 A.M. TO 12:15 P.M.
Session 2aPAb
PhysicalAcoustics: Materials Characterization
John A. Burkhardt, Chair Departmentof Engineering,Indiana-Purdue University at Ft. Wayne,2101 East ColiseumBoulevard, Ft. Wayne,Indiana 46805-1499
ContributedPapers
8:30 Scholtewave diffractionby a dihedral:the generationof the transmitted and reflectedScholte waves, and the generalizedRayleigh waves. The 2aPAbl, Determination of velocity and attenuation of shear waves studywas extendedto the A wave diffractionon a thin plane plate. The using broadbandpulse technique. JunruWu (Dept. of Phys.and dimensionsof the squaresection of the defect were half of the plate Mater. Sci. Program,Univ. of Vermont,Burlington, VT 05405) thickness.In thiscase, the wavesgenerated were generalized Lamb waves. The ultrasonicspectroscopy (broadband pulse} technique was applied to simultaneouslymeasure phase velocity and attenuationcoefficient of shearwaves in a solid in the megahertzfrequencies. This techniqueis an 9:15 extensionof the ultrasonicspectroscopy technique currently used in deter- miningdispersion of longitudinalwaves. Sources of errorin measurements 2aPAb4. Analysis and optimization of wedge transducersfor Lamb includingdiffraction loss and nonlinear distortion will bediscussed. [Work wave excitation. F. Levent Degenekin and Butrus T. Khuri-Yakub supportedby Hewlett-PackardCo.] (StanfordUniv., E. L. GinztonLab., Stanford,CA 94305) Wedgetransducers are commonlyused to excite and detectLamb
8:45 wavesin solidplates for NDE purposes.In this paper,the analysisand designof wedgetransducers for efficient,single mode Lamb wave exci- 2aPAb2, Quality characterization of an electrical solder point. tationin generalmultilayered anisotropic plates is presented.The incident MohamedEzzaYdi, All Moudden (Lab. d'Instrumentationet de Mesures, acousticfield distributionon the surfaceof the plate due to a wedge Facult6des Sciences, Univ. lbnouZohr, Agadir, Morocco), Dominique transducerwith arbitraryapodization is calculatedusing the angularspec- Decultot, and Gtrard Maze (Universit6 du Havre, 76610 Le Havre, tram method.Then, the particlevelocily and stress field distributionsin the France) plate in responseto this source is obtained by the surface impedance approach.This field distributioncan be expressedas a sumof Lamb wave The Lamb wavesare guided modeswhich propagatein a plane layer. modesin the structure,since the Lamb wavesform an orthogonalmode The A, antisymmetricand S, symmetric(i = 1,2.... ) Lamb waves have basis.Once the modeamplitudes are found,the excitationefficiency for an infinitephase velocity in low frequencies(cutoff frequencies}, and the the desired Lamb wave mode is calculated. The results indicate a trade-off phasevelocity limit, in high frequencies,is equalto the velocityof the betweenefficiency and multimodeexcitation, as expected.To achieveboth shearwave in the isotropicsolid material. The thicknessresonance of an highefficiency and single mode excitation, an optimizationscheme is used elasticplate normally insonified by an ultrasonicplane wave is relatedto wherethe parametersinvolve the frequencyof operation,dimension of the the cutoff frequencies.From theseresonance frequencies, the plate thick- wedge,and the apodizationfunction. The resultsof this analysisare pre- nesscan be easilydeduced. In thispresentation, a focusedultrasonic trans- sentedfor variouspractical examples. ducerwith a largebandpass to characterizean electricalsolder point be- tween two steel sheets is used. This solder is abundantlyused to manufacturecars. An experimentalultrasonic pulse method (pulse-MIR) 9:30 allowsus to plotacoustic spectra. The solderis placedin the focalspot of the beam. The transducercan be moved in a parallel direction to the 2aPAb5. Experimental study of Lamb waves having a negative surfaceof thesheet steel. Many timesignals are recorded along a diametri- energy vdocity in a thin plane plate imme•ed in liquid. Yennick cal line with a smallstep. For eachtime signala spectrumis computed. Endcline,Hugues Duflo, and Jean Duelos (Lab.d'Acoust. Ultrason. et The resultsare shownwith a graphicalsoftware. The falsecolor images d'Electron.,Univ. Le Havre, 76610 Le Havre, France) allow us to evaluatethe solderquality. Lambwaves having a negativeenergy velocity have been theoretically predicted;they are called negative waves for short.This wordis usedif the 9:00 phasevelocity is in the oppositedirection to the energyvelocily. When a plate is immersedin a liquid, this phenomenonstill occurs.These waves 2aPAb3. Experimental study of the Scholte wave interaction with a becomeleaky as their energy is being reradiatedinto the liquid. Any square section defect. Alain Tinel, Hugues Duflo, and Jean Duelos negativewave has the samelimit frequencyas a Lamb wave,and the same (Lab. d'Acoust. Ultrason. et d'Electron., Univ. du Havre, Place Robert Schuman,76610 Le Havre, France) label with a prime(') sign (i.e., S2-S•). Somecommon solids were studied:duralumin, stainless steel, brass,and glass.The negativewaves In this work, an experimentalstudy of surfacewave diffractionon a were generated(as Lamb wavesare) by a tone burstbulk wave and ob- substrateimmersed in wateris presented.The Scholtewave wasgenerated servedafter propagation over the plate by translatingone of thetransducers by bulk waveconversion at the extremityof the substrate.The samplewas in orderto receivethe negativewaves. The existenceof severalnegative a planeplate of duralumin10 mm thick and 200 mm long whichhad a waveswas proved; especially the A; glasswave which can be observed defect(a tenonor a mortise)with squaresection dimensions close to the quite easily.When the frequencyX thicknessproduct decreases, several wavelengthof thewave in thefluid. Only oneobstacle perpendicular to the propertieswere observed in accordancewith the theory:(i) the absolute directionof propagationof theincident wave was investigated. The acous- valueof energyvelocity increased and reached a maximumnear the cutoff tic pressureat 300 mm aroundthe diffraction zone was recorded. Phenom- frequency,(it) the attenuationincreased. A time-frequencystudy follows ena of modeconversions were observed.They were the sameas in the whichenables the calculationof the energyvelocity.
2467 J. Acousl.Soc. Am., Vol. 99, No. 4, Pt. 2, Apdl 1996 131st Meeting:Acoustical Sociely of America 2467
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 9:45 dersin the caseof very weakanisotropy. The validityof the mathematical modelis verifiedfirst by applyingit to the familiar caseof an isotropic 2aPAb6. Experimental study of A wave propagationalong a plane aluminumcylinder. The model is then appliedto a transverselyisotropic or curvedplate in contactwith two difl}rent liquids. Lo¾cMartinez, cylindergenerated by perturbingvarious elastic constants of the isotropic JeanDuelos, Alain Tinel, and Nanm Veksler (Lab. d'Acoust.Ultrason. et aluminumcylinder. The mannerin whichthese perturbations affect each of d'Electron., Univ. Le Havre, Place Robert Schuman, 76610 Le Havre, lhe Rayleigh,Whispering Gallery, and longitudinallyguided wave modes France) is shownto be consistentwith elasticitytheory and modal shapes of these TheA wavepropagation was first studied on 200-mm-longplane plates resonances.Some experimental results are alsopresented. madeof brass.The plateswere 0.2 or 0.1 mm thick.The externalfluid was alwaysdistilled water, and air, water,propanol, or glycol was usedas 10:45 internalfluids. With propanolor glycol.a secondwave was observed, calledA*, similarto the A wave but havinga strongattenuation in the 2aPAb9. The Kirchhoff-Helmholtz integral theorem and related directionof propagation.Using time frequencytechniques, group disper- identifies for waves in an inhomogeneousmoving fluid. Oleg A. sioncurves were shownto be a functionof the frequencythickness product Godin (School of Earth and Ocean Sciences,Univ. of Victoria, P.O. Box in the range0.1-1 MHz min. When possible,the phasevelocity was de- 1700, Victoria, BC V8W 2Y2, Canada) rived from experimentalresults using the phaseof the signalspectrum. Experimentalresults presented a very goodagreement with theoretical The Kirchhoff-Helmholtzintegral theorem (KHT), which expresses values.The A and A* wave propagationswere then investigatedusing the wave field in a volumeinside (or outside)a givensurface in termsof cylindricalbrass boxes. The thicknesswas also0.2 or 0.1 rnm and the the field'svalue on the surface,is well knownand widely usedin acoustics radiuswas 60 min. The box was filled with air, distilledwater, propanol, or of motionlessmedia. In thispaper, an extension of thetheorem to acoustic- glycol.The experimentaldispersion curves were comparable to thosein gravitywaves in an arbitraryinhomogeneous moving fluid is obtainedas a thecase of planeplates. If propanolor glycolwere used, A* or A waves corollaryof the reciprocity-typerelations constituting the recentlyestab- (respectively)were detected tangentially. Their attenuation was also mea- lishedflow reversaltheorem (FRT) [O. A. Godin,J. Acoust.Soc. Am. 97, sured. 3396(A)(1995); 98, 2866(A)0995)]. The KHT takesa conciseform when statedin termsof acousticpressure and oseillatorydisplacement of fluid particles.The KHT is appliedto studyuniqueness of solutionsto acoustic 10:00-10:15 Break boundaryvalue problemsin movingmedia and to establishunitarity and othergeneral properties of the scatteringmatrix for surfaceand volume 10:15 scatteringas well as in an irregular(range-dependent) waveguide with flow. Relationof the scatteringmatrix propertiesto the FRT and to wave- 2aPAb7. Elastic interfacial waves in orthotropic interlayers. actionconservation is discussed.[Work supported by NSERC.] DimitriosA. Sotiropoulos(Dept. of Mech.,Mater. and Aerospace Eng., Illinois Inst. of Technol.,Chicago, IL 60616 and Dept. of Eng. Sciences, Tech. Univ. of Crete, Chania73100, Greece) 11:00
Elasticinterfacial waves propagating along one of the planarbound- 2aPAb10. Sound propagation in a periodically lined duct with a ariesseparating an orthotropicinterlayer of arbitraryuniform thic •kness fluid flow. SusaonBoij (Dept. of Mech. Eng., Rm. 3-445, MIT, from an orthotropicinfinite surroundingsolid are studied.The axes of Cambridge,MA 02139) and B6rje Nilsson (KTH, 100 44 Stockholm, materialsymmetry of the two materialsare alignedwith one of the axes Sweden) coincidingwith thepropagation direction and another being perpendicular to the interfaces.The dispersionequation is derivedin explicitform yield- Resonantlining is an effectivemeasure to reducetonal noisein ducts. ing the interfacialphase or groupspeed in termsof frequency,nondimen- It hasbeen observed that a fluid flow in the ductcan interact with the lining sionalizedwith respectto the interlayerthickness, and the elastic constants in sucha way that soundis amplified.A modelfor the acousticperfor- and massdensities of the intedayerand the surroundingsolid. Limiting manceof an infiniteduct with periodic lining (quarter wavelength resona- casesof the dispersionequation give the secularequation for interfacial tors)and a nonzeromean velocity is developed.The fluid in the ductand {StoneIcy)waves in two semi-infiniteorthotropic materials and the fre- liningare separated by an infinitelythin shear layer, the velocity in theduct quencyequation for an orthotropicplate. Analysis of the dispersionequa- is uniform,and the velocityin the liningis zero.Such a layer is unstable tionreveals several features. Under parameter conditions which are defined for all frequencies,a so-calledHelmholtz' instability. The linearacoustic propagationat low frequenciescannot occur. Also materialparameter com- equationsare assumed to be valid.Based on thebuilding block method, the binationsare found for which interfacialwaves of arbitrarywavelength as acousticmodes in the periodicstructure are calculated from the ductmodes comparedto the interlayerthickness cannot propagate. Finally, the exist- and scatteringeffects of the sharpedges. Numerical computations are done ence of standingwaves as solutionsof the bifureafionequation, a special for a numberof cases,where higher-order,evanescent, acoustic Floquet caseof the dispersionequation, is definedwith respectto the parametersof modesare omitted in order to simplify calculations.The direction of the interlayerand the host material. propagationof the computedmodes is determinedby the requirementof causality.
10:30 11:15 2aPAbS. Scattering of an obliquely incident wave by a transversely isotropiccylinder. FarhangHonarvar and AnthonyN. Sinclair (Dept. of 2aPAbll. Giant sonic stop bands in 3-D periodic array of liquid Mech. Eng., Univ. of Toronto,5 King's CollegeRd., Toronto,ON M5S balloons. Manvir S. Kushwahaand RamaN. Singh (Institutode Fisica, 3G8, Canada) UniversidadAutonoma de Puebla,Apdo. Post. J-48, Puebla 72570, Mexico) While the scatteringof a planeacoustic wave from a solid isotropic cylinder has been extensivelystudied for the past severaldecades, ve• Periodicbinary systems can createcomplete acoustic bandgaps (i.e., little hasbeen investigated regarding scattering from anisotropiccylinders. stopbands) within which soundand vibrationsare forbidden.This is of In this paper,the mathematicalformulation for the scatteringof a plane interestfor applicationssuch as acousticfilters, noise control, and im- acousticwave incidentat an arbitraryangle ot on an infinite transversely provementsin transducers;as well as for purephysics concerned with tho isotropic cylinder is developed.The normal mode solution is based on Anderson localization of sound and vibrations. The band structures for 3-D deconplingof the SH wave from the P and the SV waves.The resulting periodicarrays of waterballoons surrrounded by mercuryhave been com- partialdifferential equations have closed-formsolutions and the scattered puted.Complete, multiple stop bands are foundfor fec,bcc, and sc lattices. pressurefield can be calculatedat any point outsidethe cylinder.The It is stressedthat sucha simple3-D inhomogeneoussystem exhibits the solutiondegenerates to the well-knownsimple model for isotropiccylin- wideststop bands ever reportedfor elasticas well as for dielectriccom-
2468 J. Acoust.Soc. Am., VoL 99, No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society of America 2468
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 posites.The gap/mid-gapratios are foundto be as high as - 1. For mer- rangeof existenceof the two (one homogeneousand the otherhomoge- curyballoons surrounded by waterthe gaps are foundto be comparatively neousor inhomogeneous)reflected waves in termsof the angleof inci- muchsmaller. Physical importance and applicationsof suchgaps will be denceof a homogeneouswave, the orientationof the free-surfacewith discussed. respectto a materialaxis of symmetry,and the elasticconstants of the monoclinicmaterial. The criticalorientation beyond which there exist two
11:30 homogeneousreflected waves is derivedin explicitform in termsof the elasticconstants. One of thesereflected waves has an angle of reflection 2aPAb12. Diffuse field decay curvature for material equalto the angleof incidenceonly for specificorientations which are characterization. JohnBurkhardt (Dept. of Eng., PurdueUniv., 2101 found. In the rangeof existenceof the two reflectedwaves, exclusion ColiseumBlvd. E., Ft. Wayne, IN 46805) pointsare defined for whichthere exists only one reflected (homogeneous) wave with nonzeroamplitude. A new quantitativetechnique is proposedfor determiningboth the concentrationand spatial extent of viscousdissipation in dynamicsystems. Whendissipation is distributedunevenly within a system,nonexponential responsedecays can result within certain frequency ranges. Unlike typical 12:00 exponentialdecays that carry volumeaveraged information about the 2aPAb14.Ultrasonic velocity and attenuationof nano-scaledcopper strengthof dissipation,nonexponential decays carry informationabout measured by laser ultrasonic technique. Xiaorong Zhang, boththe strength and distribution of dissipationin thesystem. Two param- etersdescribe the nonexponential decay process and can be directlyrelated ChangmingGan, Shiyi Zhang (StateKey Lab. of ModernAcoust. and Inst. of Acoust.,Nanjing Univ., Nanjing210093, China),Yuying Hauny, to the strengthand spatialextent of the dissipation.It is proposedthat fittingobserved nonexponential decays to thepredicted model may provide and DingchangXian (Lab. of SynchrotronRadiation, Inst. of High a method for the nondestructive determination of both the extent and se- EnergyPhys., Chinese Acad. of Science,Beijing 100039, China) verityof dissipationcausing defects in materials.The presentedwork con- The velocityand attenuationof an tdtrasoniclongitudinal wave for centrateson acousticsystems and providesa testof the proposedconcept. nano-scaledcopper are determinedby a laserultrasonic technique. The Theoreticalpredictions are presented and compared with numericalexperi- nano-scaledcopper samples are composed of superfine particles 10-rim in mentsto determinethe effectivenessof the proposedapproach. size,and are preparedby a suppressingand sinteringtechnique under a vacuum,and different pressures are used in theexperiment. These samples 11:45 are of thicknessesbetween 125-300/xm. The experimentalresults show
2aPAb13. On the reflection of elastic waves in monoclinic thatthe velocity dispersions and attenuation spectra of nano-scaledcopper dependon theirfabrication technology conditions, which are different incompressiblematerials. DimitriosA. Sotiropoulosand Sudhakar from thoseof conventionalCu. The attenuationof nano-scaledcopper is Nair (Dept. of Mech., Mater.,and AerospaceEng., Illinois Inst. of proportionalto the frequencyof ultrasound,and some absorption peaks Technol.,Chicago, IL 60616) appearat thecurves of attenuationversus frequency, but the attenuation of Thereflection of planeelastic waves from a freesurface of monoclinic conventionalCu is proportionalto thesquare of thefrequency. The veloc- incompressiblematerials is examinedunder plane strain conditions in a ity of nano-scalcdcopper is lowerthan that of conventionalCu. The ex- planeof materialsymmetry. The propagationcondition is derivedwhich perimentalsystem, measurement method, results, analyses and discussions togetherwith the law of reflectionyields an inequalitythat defines the are also presented.
TUESDAY MORNING, 14 MAY 1996 REGENCY A AND B, 8:30 TO 11:50 A.M.
Session 2aPP
Psychologicaland PhysiologicalAcoustics: Psychoacoustics and DavidM. Green
William A. Yost, Cochair ParmlyHearing Institute, Loyola University, 6525 NorthSheri&m Avenue Chicago, Illinois 60626
Ervin R. Halter, Cochair Departmentof Psychology,University of California,3210 Tolman Hall #1656Berkeley, California 94720
Chair's Introduction--8:30
Invited Papers
8:35
2aPP1.Effects of modulatorphase for comodulationmasking release and modulation detection interference tasks. Virginia M. Richardsand Emily Buss (Dept. of Psych.,Univ. of Pennsylvania,3815 Walnut St., Philadelphia, PA19104) Threeexperiments evaluated the joint effects of targeffmaskerfrequency separation and modulator phase on modulation detection interference(MDI) andcomodulation masking release (CMR). The tasks were (a) detectionof thesinusoidal amplitude modulation (SAM)of a tone,(b) discrimination ofchanges inmodulation depth of a SAMtone, and (c) detection ofa toneadded to a nan'owband of noise.Thresholds were obtained for either the target alone, or the target presented with two maskers. The target frequency was 1500 Hz. Themaskers were above and below the target at frequencyseparations ranging from 1/3 to 2 oct.The maskers were either tones ormaskers appropriate forthe task (SAM tones or noise). For nontonal maskers, themasker envelopes were either coherent orrandom
2469 J. Acoust.Soc. Am., Vol. 99, No.4, Pt.2, April1996 131stMeeting: Acoustical Society of America 2469
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 with respectto the envelopeat the targetfrequency. Substantial individual differences were obtained. When the tonalmaskers led to only modestmasking, effects of target/maskerenvelope randomization tended to occurfor frequencyseparations less than an octave. The resultssuggest a dependenceon interactionswithin a single,relatively broadband analyzer. [Work supported by NIH andUniv. Penn.Research Foundation.]
9:05
2aPP2.Individual differences in humansound localization behavior. FredericL. Wightman(Waisman Ctr. and Dept. of Psych., Univ.of Wisconsin,Madison, WI 53705) andDoris 1. Kistler (Univ.of Wisconsin,Madison, WI 53705)
Resultsfrom studiesof the apparentpositions of virtual and real soundsources conducted over the past 5 years reveal large individualdifferences. To characterizethese differences in global termssuch as accuracyor variancedoes not tell the whole story. Listenersdiffer in the extent to which they make front-back or back-front confusions,the extent to which they report apparent positionsabove or belowthe horizontalplane, the resistanceof theirjudgments of apparentposition to interaurallevel imbalance,and otherfactors. It seemsclear that some of thesedifferences might be tracedto differencesin outer-earacoustics. Since pinna shapes vary tremendouslyfrom person to person,there are large individual differences in theresulting head-related transfer functions (HRTFs). The cuesprovided by the direction-dependencyof HRTFs are knownto be important,especially for determiningapparent source elevation. HRTFs lackingin detailprovide ineffective cues and thus listeners must adopt differing strategies for combiningHRTF cueswith other cuesto detemfinesource position. Unfortunately detailed analyses of both HRTF differencesand differencesin localizationbehavior doesnot reveal a simplerelationship. [Work supported by NASA andNIDCD.]
9:35
2aPP3. Time for a new form of temporal integration. Roy D. Patterson (MRC Appl. Psych.Unit, 15 ChaucerRd., Cambridge CB2 2EF, UK)
Dave Greenhas repeatedly emphasized the paradoxin the leakyintegrator model of temporalprocessing and stressed the needfor newapproaches. Recent experiments at APU on envelopeasymmetry, period jitter, andfine-structureregularity reinforce the paradox. When "damped"noise with a repeatingexponential envelope is time reversed("ramped" noise), it altersthe envelopeand carder percepts,supporting damped/ramped discrimination for envelopeperiods from 8-125 ms.The Weberfraction for jitter on theperiod of a click train peaksaround 60 ms; perfectlyregular click trainssound irregular in thisregion reducing jitter detectionrelative to longerand shorter periods. These experiments suggest a longtime constant for theleaky integrator. When iterated rippled noise masks randomnoise, it is 15dB lesseffective than the equivalent random noise; low-level random noise disrupts thefine-structure regularity of iteratednoise. This suggestsa short time constant, since values over 8 msremove the fine-structurethat appears to underlythe timbrediscrimination. "Strobed temporal integration" offers a potentialsolution to theprimary paradox; the fine-structure of periodic soundsis preservedin an "auditoryimage" which decays relatively slowly thereafter. [Research performed at APU in collaboration with Drs.Akeroyd, Allerhand, Datta, Handel, lrino, Lorenzi, Tsuzaki, and Yost.]
10:05--10:20 Break
10:20
2aPP4.Altered temporaland spectralpatterns produced by cochlearimplants: Implications for psychophysicsand speech recognition.Robert V. Shannon,Fan-Gang Zeng, and John Wygonski (House Ear Inst., 2100 W. ThirdSt., Los Angeles, CA 90057) Cochlearimplants produce highly unnatural temporal and spatial (tonotopic) patterns of neuralactivation in theauditory system, and the patternsmay vary considerablyfrom patientIo patient.In spiteof theseabnormal pattams, psychophysical measures of temporalprocessing are relatively normal in patientswith cochlear implants and brainstem implants. A highlevel of speechrecognition is possiblewith only three bands of modulatednoise [Shannon et al., Science270, 303-304 (1995)].What parameters of the peripheralactivity pattern are criticalfor the transmissionof speechpat•ro information?Four-band speech processors were con- struttedwhich reducedthe spectralinformation in speechto four, amplitude-modulatednoise bands. Variations were constructedthat alteredthe location,spectral extent, overlap, and amplitudecompression of the four noisebands relative to the originalspeech. Manipulationsof the bandoverlap and the cut-offfrequencies dividing the bandshad relativelylittle effecton speechrecognition. However,amplitude compression and the tonotopic misalignment of noisebands with the speechcues resulted in severereductions in speechrecognition. These experiments and the performancelevels of presentcochlear implant patients demonstrate that normal temporalinformation and considerable speech information can be received with relatively poor tonotopic selectivity. [Work supported by NIDCD.]
10:50
2aPPS.The index of interaural correlation:Accounting for binaural detectionacross center frequency. LeslieR. Bernstein (SurgicalResearch Ctr., Dept. of Surgery,Otolaryngology, and Ctr. for NeurologicalSciences, Univ. of ConnecticutHealth Ctr., Farmington,CT 06030) Investigationsin this laboratory demonstrated that the normalized correlation accounted well for listeners'performance in binaural tasksutilizing high-frequency stimuli for whichthe envelopes convey the interaural information. This outcome means that the non-zero meanof theenvelopes must be included in thecomputation of the correlation. Due to peripheralauditory processing analogous to rectificationand low-pass filtering, the "internal" representations of auditory stimuli have nonzero means regardless of their frequency. Thisstudy evaluated whether the normalized correlation computed subsequent to rectification and low-pass filtering could account for detectiondata at low andintermediate, as well as highfrequencies. In a four-interval,two-alternative task, listeners detected which intervalcontained a tone (between 500 Hz and2 kHz)added antiphasically to diotic, 100-Hz-wide, noise (NoSrr). "Nonsignal" intervalscontained the toneadded homophasically (NoSo). Performance was measured for S/Nsbetween - 30 and +30 dB. For all
2470 J. Acoust.Soc. Am., VoL 99, No.4, Pt. 2, April1996 131stMeeting: Acoustical Society of Amedca 2470
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 S/Ns,overall level was 70 dB SPL.Normalized correlation (unlike the correlation coefficient) described performance well, as a functionof S/Nand center frequency. The parameters of the rectifier and low-pass filter required to describethe data will bediscussed. [Supportedby researchGrant No. 5R01DC0210302,National Institute on Deafness and Other Communication Disorders, NIH.]
11:20
2aPP6.Temporal cues in monauraland binauraldetection and discHm•nation. David A. Eddins (Psychoacoust.Lab., Dept. of Speechand HearingSciences, Indiana Univ., Bloomington,IN 47405)
The auditorysystem can extracttemporal information from complexstimuli to performa varietyof detectionand discrimination tasks.At low stimulusfrequencies, the auditorysystem may encodestimulus fine structureand temporalenvelope. At higher frequencies,the codingof fine structurediminishes as phaselocking deteriorates, while the codingof the temporalenvelope remains. The presentstudy investigated the relativecontributions of interauraldifferences in stimulusenvelope and fine structureto the masking level difference(MLD). NoSo and NoS thresholdswere measuredat stimulusfrequencies of 500 and 4000 Hz usingtwo typesof narrow-band(50 Hz) noise:Gaussian and low-noisenoise. Gaussian noise maskers yielded MLDs of 15 at 500 Hz and9 dB at 4000 Hz, the reductionreflecting minimal fine structurecues at 4000 Hz. Low-noisenoise yielded lower NoSo and higher NoS thresholds than Gaussiannoise. MLDs of 8 at 500 Hz and 0 dB at 4000 Hz reflectedminimal maskerenvelope cues in both conditionsand reducedfine structurecues at 4000 Hz. While the patternof resultswas consistent, threshold differences among the six listenerswere substantial.Additional MLD conditionsand data from CMR and noise discriminationtasks employing low-noise noise will be discussed.
TUESDAY MORNING, 14 MAY 1996 NATIONAL PARKS, 8:30 TO 11:30 A.M.
Session 2aSC
SpeechCommunication: Models and Measurements
Marlos S. Fourakis, Chair Speechand Hearing Science,The Ohio State University,1070 CarmackRoad, 110 Pressey,Columbus, Ohio 43210-1372
Contributed Papers
8:30 intervals.Reported here are across-sessioncomparisons of lip-jaw dis- placements.velocities, temporal ordering, and relative timing for bilabial 2aSCI. Iceberg revisited. Osamu Fujimura (Dept. of Speechand closureat normal rates. Four of the seven subjectsshowed stable but HearingSci., Ohio StateUniv., Columbus, OH 43210-1002) idiosyncraticspatial and temporal organizational characteristics within and Icebergpatterns refer to a particularpart of the flesh-pointcoordinate acrosssessions. Subjects who are relatively unstableacross sessions in timefunction of a crucialarticulator for anobstruent gesture [O. Fujimute regardto displacementcharacteristics are also relatively unstable in regard andW. Spencer,J. Acoust.Soc. Am. Suppl.1 76. S59(1983)]. They were to temporalordering and relative time. Only motorequivalence covariabil- foundstable for a givendemisyllable in differentprosodic contexts, when ity is stableacross sessions for all subjects,that is, even in the caseof a microbeampellet heightvaluc, aroundwhich the time functionwas unstablespatial and temporalorganizational characteristics. Results seem excisedfor comparison.was optimally selected. The time for crossingsuch to supporta task-dynamicpoint of view, namely,that the spatialand a .selectedthreshold height was found useful for studyingphonetic phras- temporalorganizational characteristics of the individualarticulators that ingpatterns. The C/D model[O. Fujimura,J. Acoust.Soc. Jpn. (E) 13, comprisean articulatorycomplex represent the naturalconsequence of 39-48 (1992);O. Fujimura,Proc. [CPhS 3, 10-17 (1995)]proposes that gesturalcoordination (inferred here by motorequivalence index) and the articulatorycontrol function is composedof impulseresponse func- thereforewould not demonstrate stability across sections. [Work supported tions(IRFs) for elementalgestures, which are magnified according to the by NIH DC-00121to HaskinsLaboratories and University of Illinoisre- syllableSlrength. Therefore, the movcment velocity at a giventime relative searchgrant.] to thesyllabic pulse (i.e., in a givenphase of transition)will varyaccording to the syllablemagnitude. The two approximationprinciples will be shown 9:00 to be mutuallyconsistent when the saturationeffects of the physicalar- ticulatorysystem is consideredalong with generalproperties of the IRFs 2aSC3. GIottal geometry and phonation threshold pressure in a for obstrucntgestures. [Work supportedin part by researchand education vocal fold physical model. Roger W. Chart, Ingo R. Titze, and fundsprovided by ATR/ITL andATRIHIP.] Michael R. Titze (Dept. of SpeechPathol. and Audiol. and Natl. Ctr. for Voiceand Speech, Univ. of Iowa,Iowa City, IA 52242) 8:45 The effectof convergentand divergent prephonatory glottal geometries on phonationthreshold pressure was investigated using a previouslyre- 2aSC2. Acrosssession variability in lip-jaw synergiesfor bilabial portedphysical model of thevocal fold mucosa[Titze et al.. I. Acoust. closure. Peter.L Alfonso (Dept. of Speechand HearingSci., Univ. of Soc.Am. 97, 3080-3084(1995)]. Lowest offset phonation threshold pres- Illinois,901 S. SixthSt., Champaign,[L 61820) surein the rangeof 0.07 to 0.23 kPa wasobtained for a rectangularor a Movementsof the tongue,lips, andjaw were transducedby electro- near-rectangularglottis (with convergentor divergentangle •<3 ø) across magneticmidsagittal articulography. A single session included 20 repeti- differentglottal half-widths between 2.0 and6.0 min.Phonation threshold tionsof \pap\,\tat\, and\sas\ imbeddedin a carrierphase al normal,slow, pressurefor moreconvergent or divergentglottal geometries was consis- and fastspeech rates. Seven talkers completed three sessions at I-week tentlyhigher. This findingonly partiallyagrees with previousanalylical
2471 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 247
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 work whichpredicts a 1oweslphonation threshold pressure for a divergent sequences/aCV/,where C was eitherIpl or/b/and V one of the vowels glottis[I. R. Titze,J. Acoust.Soc. Am. 83, 1536-1552(1988) and J. C. /i, a, u/. Forceof labialcontact and oral air pressurewere also recorded in Lucero,J. Acoust.Soc. Am. 98, 779-784 (1995)].The discrepancybe- one subject.The resultsindicate that at the instantof oral closure,the tweentheory and data is likely to be associatedwith flow separationfrom velocityof both lips was closeto peakvelocity. They alsoshow that the a divergentglottis. [Work supported by NIH.] lower lip continuedits upward movementafter oral closure.This was reflected in the force of labial contact, which showed an increase in contact 9:15 pressureafter the oral closure had occurred. During the periodof lowerlip upward movementafter the oral closure,the upper lip often showeda 2aSC4. Effects of driving pressure and recurrent laryngeal nerve correspondingupward movement, suggesting that the lower lip mightbe stimulation on glottic vibration in an in vivo constant pressure pushingthe upper lip. Theseresults support the hypothesis that one goal in model of phonation, Andrew Verneuil, Jody Kreiman, Kevin makingthe lip closureis a regionof negativelip aperture.[Work supported Kevorkian,Ming Ye, BruceR. Gerratt,and Gerald S. Berke (Div. of Head by NIH.] and Neck Surgery,UCLA Schoolof Medicine,CHS 62-132, Los Angeles, CA 90095)
Most in vivo studiesof phonationhave used constantflow models. However,because the lung-thorax systemis betterviewed as a constant pressuresource, a constantpressure in vivo caninemodel was developed. 10:15 In thismodel, driving pressure and recurrent !aryngeal nerve (RLN) stimu- lation are independentvariables, and subgiotticpressure (Pan,; measured 2aSC7. Lip protrusion movementsin normal versus dear speech. immediatelyunder the glottis),air flow,fundamental frequency (F0), and PascalPerrier, Joseph S. Perkell,and Melanie L. Matthies (Res.Lab. of glotticarea are dependentvariables. !n threedogs, P•b andair flow were Electron.,Rm. 36-511,MIT, Cambridge,MA 02139) measuredwith constantRLN stimulationand varying driving pressure, and in anothercondition with constantdriving pressureand varying RLN A kinematicanalysis of midsagittalmovement (EMMA) datawas per- stimulation.Videostroboscopic measures on four animalsassessed glottic formedfor upperlip protmsionfrom [i] to [u] in [iku],[ikku], and [iktku], areaswith constantRLN stimulationand varying driving pressure.With producedby a speakerof AmericanEnglish. Utterances were embeddedin constantRLN stimulation,increasing driving pressurehad no effect on a cardersentence and spokenin four conditions:normal rate, normalrate glottic area, while F0, and air flow increasedsignificantly. Changes in andclear, fast rate, fastrate andclear. The resultsshow several regularities P•ubwere small in comparisonto changesin driving pressure.With con- acrossall conditions:(1) the delaybetween the protrusiononset and the stant driving pressure,increasing RLN stimulation increasedP,,b and acousticonset of Jul varieslinearly with the vowel-to-vowelduration F0 and decreasedair flow_These findings suggest that Pm• during pho- (VVD), [i]-endto [u]-onset,with a slopeof 0.7; (2) theoverlap between nation is primarily dependenton RLN activity and associatedlaryngeal theprotmsion movement and vowel Ill decreasesas VVD increases,with muscularcontraction, but not on lungdriving pressure. [Work supported no significantdifferences between conditions for similarVVD values;(3) by VA Merit Reviewfunds.] the relationshipbetween the ratio of maximumvelocity (Vm•) to protru- sion amplitude (Amp) and the movementduration (T) is constant: 9:30 V,/Amp= clT; (4) thenumber of velocitypeaks increases linearly with 2aSC5. Annealing in a geneticalgorithm for task-dynamicrecovery VVD. Theseregularities suggest that the samecontrol strategy underlies from speechacoustics. RichardS. McGowan (HaskinsLabs., 270 the protmsiongesture, whatever the condition.However, for a givenrate, Crown St., New Haven, CT 06511) cleartokens were producedwith longerVVDs and largerprotrusion am- plitudes.For similarVVD values,fast clear tokenshad largervalues of Genetic algorithms,as they have been used for recoveryof task- Vm• thannormal tokens. [Work supported by NIDCD andNATO.] dynamicparameters JR. S. McGowan,"Recovering articulatory move- mentfrom formantfrequency trajectories using task dynamics and a ge- neticalgorithm," Speech Commun. 14, 19-49 (1994)],can take some time to converge,which means that expensivefunction evaluations are neces- sary to obtain optimumsolutions. In previousexperiments, each task 10:30 dynamic-target was always given 6 bitsin the chromosome.In the tests reportedhere, the numberof bits in the chromosomestring representing 2aSC8.Variation of subglottalpressure during sentenceproduction: targetpositions was made a functionof generation,with the range of the Effect on glottal source amplitude and spectrum. Helen M. Hanson targetsremaining constant to see whetheran annealingprocess with ever (SensimetricsCorp., 26 LandsdowneSt. andRes. Lab. of Electron.,MIT, increasingresolution would speedconvergence to a good fitnessmaxi- 50 VassarSt., Cambridge,MA 02139) mum. Resultsshow that annealingcan be helpful in speedingconvergence, althoughnot all annealingschedules help. This procedureis related to With thegoal of synthesizingnatural-sounding speech based on higher- simulatedannealing where the temperatureof the searchis decreasedas level parameters,variations in subglottalpressure for sentenceshaving the searchprogresses. It is also related to codebooklook-up used in the differentstress patterns have been studied. A Rothenbergmask was used to inverseproblem, where vocal tract shapes that produce speech close to that collectoral pressureand airflow signals from severalsubjects producing of the dataare accessed to initializea subsequentoptimization procedure. [Worksupported by NIH GrantDC-01247 to HaskinsLaboratories.] reiterantspeech. Acoustic sound pressure was also recorded, and sound pressurelevels (SPLs) for bothreiterant and naturalutterances were com- paredto verify the suitabilityof reiterantspeech for the task.Subglottal 9:45-10:00 Break pressurePs wasinferred from oralpressure measured during stop conso- nantclosure of reiterantspeech, average glottal flow U s wasestimated 10:00 fromthe low-pass-filtered airflow signals, and average glottal area Ag was calculatedusing P, andU s . Glottalsource amplitude and spectral tilt were 2aSC6. Labial kinematics in stop consonantproduction. Anders estimatedfrom the speechwaveform. Preliminary analysis shows that ac- Lofq¾istand VincentL. Gracco (HaskinsLabs., 270 Crown St., New centedsyllables are marked by an increasein P• of about50% relative to Haven,CT 06511) the weakestunaceented syllables, an increasein SPL of 10 to 15 dB, and This studyexamines kinematic patterus of upperand lower lip move- someincrease in As . A modelfor estimatingglottal parameters during mentsin bilabialstop production with particularemphasis on eventsbefore theseutterances has beendeveloped. Attempts to synthesizesentences and duringthe oral closure.Lip movementswere recordedusing a mag- basedon this model, by includingAn andP, ascontrol parameters, are netometersystem. Five subjectsparticipated and produced 50 tokensof the described.[Work supported by NIH grants121C(}(g•5 and MH52358.]
2472 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2472
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 10:45 metricalshape of the modelhas been adapted from X-ray data.to fit the tonguecontours of a Frenchnative speaker. Movement data were collected 2aSC9. A nonlinear finite-element model of the vocal fold. Arthur P. on this speakerwith an electromagnetometer(Carstens Electronics. Loboand Michael O'Malley (BerkeleySpeech Technologies, 2246 Sixth AGI00)for the tokens [i-a], [i-el, [i-el. [a-i],[e-i]. [e-i], [i-e-œ-a], [a-e-e-i], St., Berkeley,CA 94710) [y-eel.[y-o]. [y-u], [u-y], [o-y], lee-y].[y-0e o-u], [u-o-0e-y].For each A large-displacementlarge-strain 3-D finite-elementmodel of thevocal token,the speakerwas asked to keepthe lip shapeconstant. The jaw was fold was developed.The structureis discretizedinto 720 elementswith heldin a constantposition with a smallbite-block (5 mm).For the simu- 3003 displacementand 720 pressuredegrees of freedom.The model in- lations,according to Feldman'sequilibrium-point hypothesis [A. Feldman. corporatesmaterial and geometricnonlinearities. For the constitutivelaw, "Once more Equilibrium-PointHypothesis for motorcontrol," I. Motor the Mooney-Rivlinrubber material formulation for an anisotropichyper- Behar.18 (1986)], movementwas produced by shifting,at a constantrate, elastic material is used.Average ineompressibilityconstraints are intro- the mechanicalequilibrium of the motor systemfrom one equilibrium- ducedby addinga hydrostaticpressure work term (Lagrange multiplier) to target positionto anotherone. Simulationsare assessedin the kinematic the strain energy density function.This term is a function of the bulk andacoustic spaces. [Work supportedby the EuropeanUnion.]
moduluswhich has the numericalequivalence of the penaltyparameter. 11:15 The nodaldisplacements and pressureare solvedfor independently,using a mixed displacemenffpressureformulation with 8 displacementnodes 2aSCII. The effect of lexical complexity on segmentalintelligibility. (trilinear/hexahedron)anda constant(uniform) pressure term per element. HowardC. Nusbaumand Alexander L Francis (Dept.of Psych.,Univ. of Staticcondensation of the discontinuouspressure variable at the element Chicago.5848 S. Univ. Ave., Chicago,IL 60637) level keepsthe half-bandwidthof the stiffnessmatrix the sameas for the displacement-onlyformulation. All nodeson the anteriorcommissure. vo- Most intelligibility testsare basedon the use of monosyllabictest stimuli. This constrainteliminates the ability to measurethe effectsof cal processesand the lateralsurface {attached to the thyroidcartilage) are fixed-essentialboundary conditions. An incremental-iterativestrategy lexical stresspatterns, complex phonotactic organizations, and morpho- solvesthe dynamic equilibrium equations of motionin thetotal Lagrangian logicalcomplexity on segmentalintelligibility. Since the• aspectsof lexi- formulation.The vocalfold deformationwas studied under a periodically cal structureaffect speech production (e.g., changing syllable duration), it time-varyingpressure profile {natural boundary conditions) applied on I 17 is likely thatthey affect the structureof acoustic-phoneticpatterns. It also medial surface nodes. seemsplausible that listeners make use of thisknowledge during segmen- tal perception.Thus, to the extent that text-to-speechsystems fail to modifyacoustic-phonetic patterns appropriately in polysyllabicwords. in- 11:00 telligibilitymay suffer.This meansthat while moststandard intelligibility 2aSCI0. Tongue control in speech: Some proposalstested on a testsmay accuratelyestimate segmental intelligibility in monosyllabic biomechanicalmodel. YohanPayan and PascalPerrier (lnstitutde la words,this estimate may notgeneralize prediction of segmentalintelligi- Communication Parlee. INPG & Univ. Steadhal. 46 Av. Felix Viallet. bility with more complexlexical forms.The presentstudy was carriedout F38031 Grenoble, France) to measuresegmental intelligibility in stimulivarying in lexicalcomplex- ity. Monosyllabic,bisyllabic, and polysyllabicwords were usedvarying in The abilityof a 2-D biomechanicalmodel of the tongueto reproduce morphologicalcomplexity (monomorphemic or polymorphemic).Listen- kinematicproperties of humantongue movements in V-V transitionsis ers transcribedthese stimuli spokenby two humantalkers and two text- assessed.The modelconsists of a finiteelements description, and simulates to-speechsystems varying in speechquality. The resultsindicate that lexi- the main agonis•tantagonistmuscle pairs (posterior Genioglossus/ cal complexitydoes affect the measuredsegmental intelligibility of Hyoglossusand anteriorGenioglossus/Styloglossus). The external geo- syntheticspeech.
TUESDAY MORNING, 14 MAY 1996 REGENCY D, 8:00 TO 11:50 A.M.
Session 2aUW
Underwater Acoustics:Low Grazing Angle Acoustic Penetration of the Bottom at a Kilohertz and Above
Eric I. Thorsos, Chair AppliedPhysics Laboratory, College of Ocean and Fishery Sciences,University of Washington,1013 N.E. 40th Street, Seattle, Washington98105
Chair's introduction--8:00
Invited Papers
8:05
2aUWI. Observationsof anomalousacoustic penetration into sedimentat shallowgrazing angles. IosephL. Lopes (Coastal SystemsStation Dahlgren Div., NavalSurface Warfare Ctr., Code 130B, 6703 West Hwy. 98, PanamaCity, FL 32407-7001)
Buriedmine• pogea diffieuh problemfor mine eounlermeaguresoperations. Mines may naturallybury in coastalwaters where wave-inducedeffects are significantnear the bottom.Current techniques for acousticdetection and classificationof a buriedmine requirea high-resolutionimaging sonar with bottompenetrating capability. Recently. anomalous acoustic penetration into sedimentat shallowgrazing angles was observed during a seriesof experimentswhich acoustically characterized the shallowwater environment. These experimentsemployed a stationarysonar tower completewith pan and tilt •notors.In the initial experiments,backscattered returnsfrom objectsof opportunitywere recorded;these objects were eitherpartially or completelyburied near the water-sediment interface.In a later experiment.buried calibrated retroreflectors and a buriedhydrophone were also utilized;the hydrophonewas used
2473 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society of America 2473
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 to measurein-sedh-nent sound-pressure levels. Results of the backscatteredreturns from the objectsof opportunityand calibrated retroreflectorswill be presented.Also, the measuredin-sediment sound-pressure levels will be comparedto the SAFARI (seismicand acousticfast field algorithmfor range-independentenvironments) code and will be furthercompared to resultsreported in the literature.[Work supported by the Officeof Naval Research.]
8:•0
2•UW2. Acousticpenetration of oceansediments in the contextof Biot'stheory. NicholasP. Chotiros (Appl.Res. Labs., Univ. of Texas,P.O. Box 8029, Austin.TX 78713-8029)
Acousticpenetration of oceansediments will be examinedin the light of the Biot-Stoll theoryof soundpropagation in porous media.This theoryis attractivefrom a numberof perspectives.From an applicationspoint of view, it can accountfor a numberof anomaliesthat have been observed experimentally but are notexplainable in termsof thesimpler viseoelastic wave propagation theory. From a theoreticalperspective, it providesimproved connections between the sedimentgeophysical properties, such as grain size, porosity,permeability, and frame moduli,and the acousticproperties, such as reflectionloss, sound speeds, and attenuations.The difficultyin usingBiot's theoryis mostlyin the understandingand quantificafionof certainkey input parameters,particularly the elastictoodull of the solidmatrix, andof the constituentgranular material. The potentialreward is a unifiedtheoretical frame work for researchinto ocean sediment acoustics that brings acoustics and geophysics closer together. [Work supported by ONR,Code 321 OA.]
8:55
2aUW3. Subcritical penetration of sandy sedimentsdue to interface roughness. Darrell R. Jackson,John E. Moe, Eric I. Thorsos.and Kevin L. Williams (Appl.Phys. Lab.. College of Oceanand Fishery Sciences. Univ. of Washington.Seattle, WA 98105)
Seafloorroughness can cause acoustic energy to propagateinto sedimentsfor "subcritical"incident grazing angles, that is, grazing anglessmaller than the critical angledetermined by the compressionalwave speed.Such effects must be consideredin interpreting experimentaldata on soundpenetration into sediments.The sedimentis modeledas a fluid supportingonly compressionalwaves and a twofold theoreticalapproach is used.First. an exact integralequation is solvednumerically to obtainthe penetratingfield in two dimensions.Physical insights are abstractedfrom theseresults which are also used to show that perturbationtheory is valid for problemsof interest.Using perturbation theory, a numericallytractable three-dimensional model is comparedto someof the experi- mentaldata of Chotirosand colleagues IN. P.Chotiros, J. Aeoust.Soc. Am. 97. 199-214 (1995)].The modeland data match well subjectto plausibleassumptions about roughness statistics. [Work supported by ONR.]
ContributedPapers
9:20 that may be imposedat the vertical interfacesbetween regions. This can resultin significanterrors as well as instabilities.Accurate solutions may 2aUW4. Poroacousticmedia. Michael D. Collins (Naval Res. Lab., be obtainedfor manyproblems by a conservingenergy flux at the vertical Washington.DC 20375) and William L. Siegmann (Rensselaer interfaces[M. B. Porteret eL, J. Aeoust.Soc. Am. 89, 1058-1067 (1991)]. PolytechnicInst., Troy, New York 12180) The standardexpressions for energyflux are of limitedpractical use be- Someporoelastic sediments have relatively high slow-wave speeds and causethey are nonlinear.It is possibleto obtainequivalent linear condi- low shear-wavespeeds IN. P. Chotiros,J. Aeoust.Soc. Am. 97, 199-214 tionsby writing the energyflux integrandas a perfectsquare involving (1995)].Wave propagation in thesekinds of sedimentsmay be modeled rootsof operators.The acousticcase has been resolved and some progress efficientlyby neglectingshear waves to obtainthe equationsof motionof hasbeen made for the elasticcase. Problems currently under investigation poroacousticmedia. With this approach,the number of equationsis re- includeenergy-flux conditions for poroelasticand poroacousticmedia as ducedand numericalimplementations may use largergrid spaces.Poroa- well ascorrections for problemsinvolving different types of layers.[Work eousticwaves satisfy two coupledequations. Poroelasfic waves satisfy supportedby theNRC andONR.] threecoupled equations for two-dimensionalproblems (the originalfor- mulationinvolves four equations).The equationsof poroacousficsare symbolicallyidentical to the equationsof acoustics.The poroacoustic wave equationis a vector generalizationof the variable density acoustic 9:50 waveequation [P. G. Bergmann,J. Acoust.Soc. Am. 17, 329-333 (1946)]. The interfaceconditions between poroacoustic layers are vectorgenerali- 2aUW6. A modificationof Biot theory for unconsolidatedsediment. zationsof the interfaceconditions between fluid layers.The energyflux K. MiguelNathwani and Frank S. Henyey (Appl.Phys. Lab. and Dept. of integralof poroacousticsis a vectorgeneralization of the energyflux in- Phys.,Univ. of Washington.Seattle, WA 98105) tegral of acoustics.The equationsof motionare in a form suitablefor factoringand solving with parabolic equation techniques. [Work supported A mechanismfor bottompenetration at low gra•ingangle is conversion by ONR.] of sound into Blot slow waves. Experimentsin unconsolidatedsediments havenot found Blot slowwaves with expectedparameter values, but have found them in consolidated sediments. These results led us to consider a 9:35 modificationof Biot'smodel for unconsolidated,sandy sediment. In our 2aUW5. Energy-conservation conditions for poroelastic and model,unstrained grains touch at a singlepoint, since two adjacentgrain poroacoustlewaveguides. JosephE Lingeritch, Michael D. Collins surfaceshave relativecurvature. As the grainsare pressedtogether, the (Naval Res. Lab., Washington,DC 20375), and William L. Siegmann contactarea and the stress/strainratio increase.Under extension the grains (RensselaerPolytechnic Inst., Troy, NY 12180) separateand there is no stress.The model predicts(lattice strain) • (stress)vaunder compression. This scaling law should apply to any such Wave propagationin range-dependentocean environmentsis often medium,but the numericalcoefficient depends on detailedproperties of treatedby dividing the domaininto a sequenceof range-independentre- the latticeand graingeometry. Slow wavesresulting from soundincident gions.One-way techniques, such as the parabolicequation method, are on the sediment are studied within the framework of this model. For appliedto efficientlysolve the waveequation in eachregion. The reduced simplicity,normal incidence is assumed.A positiveeffective lattice bulk orderof one-waywave equations limits the number of boundaryconditions modulusresults from sediment overburden or fromthe pressure field of the
2474 d. Acoust.Soc. Am., Vol. 99, No.4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2474
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 sound.Numerical solutions and bounds on the productionof slowwaves in intothe oceanand bottom. An equivalentformulation will be presentedin sucha mediumimply that the intensity of theslow wave is toolow to have termsof an integralequation which is solvednumerically. Average results beenobserved by the experiments. aswell as results from single realizations are presented. [Work supported by NATO.] 10:05-10:20 Break 11:05
10:20 2aUWI0. Bottom penetration at subcritical grazing angles by scattering. RalphA. Stephen (WoodsHole Oceanograph.last., 360 2aUW7. Modeling the effects of shear conversionon low grazing WoodsHole Rd., WoodsHole. MA 02543) angle bottom penetration. StanleyA. Chin-Bing (Naval Res. Lab., StennisSpace Center, MS 39529-5004)and JosephE. Murphy (Univ. of The physicsof soundpropagation and scatteringis distinctlydifferent New Orleans, New Orleans, LA 70148) betweenhard and soft oceanbottoms. A hard bottom is definedas having a shearvelocity greaterthan water velocity; a soft bottom has a shear Modelingshear conversion with finite-element/finite-differencecodes velocityless than watervelocity. Geologically hard seafloorsconsist of at a kilohertzand aboveis difficultdue to the numberof computational igneousrocks such as gabbrosand basalts;soft seafloorsconsist of sedi- elementsneeded for suchsmall wavelengths. Typically six to tennodes per ments such as mud and sand. For a soft bottom with sound incident from wavelengthare requiredto attaingood accuracy. Thus, a typicalshallow- above,total internal reflection never occurs. For all grazingangles there is watertwo-dimensional scenario can require hundreds of thousandsof com- alwaysa Snell'slaw ray pathfrom compressionalenergy in the waterto putationalelements. In thismodel study, a brute-forcehybrid approach is shearenergy in the bottom.For hard,flat bottomsover homogeneousrock, applied.The computationalresources of supercomputerswith largememo- total internal reflectionwill occur for grazing anglesless than critical. riesare combined with hybrid modeling techniques to producesimulations However in this casesound can penetratethe bottomby scatteringfrom of compressional/shear-waveconversions at low grazing anglesover surfaceroughness or volumeheterogeneities. Snapshots from time domain range-dependentbathymetry. Examples will be presentedthat illustratethe modeling by the finite-differencemethod show that the scatteredfield effectsof theseconversions in bothhorizontally stratified and inhomoge- consistsof wavefrontswhich are analogousto transmittedcompressional neousanelastic ocean bottoms. [Work supportedby ONR/NRL and by and shearbody waves. Since the seaflooris rough and laterally heleroge- High PerformanceComputing grants.] neousover a broadrange of lengthscales, this mechanismcould be sig- nificantover a broadfrequency range. [Worl• supported by ONR.] 10:35 11:20 2aUW8. The accuracy of perturbation theory for acoustic penetration of sedimentdue to interface roughness. Eric I. Thorsos 2aUWll. Near-field scattering through and from a 2-D fluid-fluid (Appl. Phys. Lab., College of Ocean and FisherySciences, Univ. of roughinterface. JohnE. Moe andDarrell R. Jackson(Appl. Phys. Lab., Washington,Seattle, WA 98105) College of Ocean and Fishery Sciences,Dept. of Elec. Eng., Univ. of Washington,Seattle, WA 98105) Lowest-orderperturbation theory (PT} is usuallyconsidered valid for modelingscattering from roughsurfaces with a smallroughness. In par- A generalanalytical expression for the time-dependentfield intensity ticular,for PT to be accuratenear the speculardirection, it is requiredthat scatteredfrom or through(penetrating) a 2-D fluid-fluidrough surface due kh'• 1, where k is the acoustic wave number and h is the rms surface to a narrow-bandincident plane wave and a narrow-bandpoint source are height.In the caseof an acousticwave incidenton the seafloor,a rough derivedand expressed in termsof the bistaticscattering cross section per interface will scattersound back into the water and also into the sediment; unitarea of thertugh surface. Even though the scattering cross section is suchscattering into the sediment will occureven when the incident grazing definedas a far-fieldquantity, this near-field result is generaland exact for angleis below the criticalangle. Here, the accuracyof PT for acoustic the specialcase of a continuouswave source and incidentplane wave. penetrationthrough a roughwater/sediment interface with a power-law Dispersionof a pulseis a functionof mediumparameters, the incident and roughnessspectrum is examinedusing exact integral equation results for scattereddirections, as well the bandwidthand centerfrequency of the the 2D problem.It is foundthat PT remainsaccurate for kh up to and well sourcesignal. First-order perturbation calculations for thecase of a Gauss- beyondunity, when the incidentgrazing angle is eitherabove or belowthe ian pulseillustrate intensity pulse dispersion effects due to forwardscat- criticalangle. The reason for this surprising result will bediscussed. [Work teringinto a Iossysediment. [Work supported by ONR.] supportedby ONR.] 11:35 10:50 2aUWI2. Peculiaritiesof low grazing angie acousticpenetration of 2aUW9. Low grazing angle scattering by a rough ocean floor. Paul the layeredabsorbing bottom. MargaritaS. Fokina (last. of Appl. E. Barbone (Dept.of Aerospace& Mech. Eng.,Boston Univ., Boston, Phys.,Russian Acad. of Sciences,46, UlyanovStr., N. Novgorod,603600, MA 02215)and Mark Spivack (Univ.of Cambridge,Cambridge CB3 Russia) 9EW, UK) Acousticreflection from the bottom and sound propagation are closely Low grazingangle acousticscattering by an irregularocean floor is connected.In thispaper reflection coefficient behavior at highfrequencies considered. The ocean bottom is modeled as a semi-infinite acoustic me- (aboveI kHz) for the layeredabsorbing bottom was investigated.Influ- dium with propertiesthat differ from thoseof the fluid above.At zero enceof the layeredbottom parameters on acousticpropagation was con- grazingincidence, a flat oceanfloor appearsacoustically soft. Surface sidered.It wasshown that for thesame set of bottomparameters the sound roughnessintroduces perturbations to both the surfaceheight and the ap- reflectioncoefficient at low grazingangles decreases when the grazing parentimpedance of theinterface. This nonuniform limit is examinedas a angledecreases. Behavior of frequencyand angle resonances of the reflec- perturbationfrom a slightlyrough pressure release surface. A modified tion coefficientswas analyzed.Two typesof bottomconnections between parabolicequation is derivedwhich describes the acousticamplitude to setsof bottomparameters and sound losses in a widefrequency band were largedistances, and takesinto accountmultiple scattering and radiation ascertained.
2475 J. Acoust.Soc. Am., Vol.99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2475
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, 14 MAY 1996 MT. RUSHMORE, 3:45 TO 4:45 P.M.
Session2pAAa
Architectural Acoustics: The Technical Committee on Architectural Acoustics Vern Knudsen DistinguishedLecture
William J. Cavanaugh,Chair CavanaughTocci Associates, Inc., 327F BostonPost Road, Sudbury,Massachusetts 01776
Chair's Introduction--3:45
Invited Paper
3:50
2pAAal. Varianceand invarlantsin room acoustics:A random walk through reverberantfields. David Lubman (David Lubman & Assoc., 14301 Middletown Lu., Westminster,CA 92683) The understandingof room reverberationhas advanced notably in recentdecades owing to the mergingof statisticalcommuni- cationtheory with room acoustics.New invariantsexpressed as simpleand robuststatistical laws governsteady-state variation of reverberantsound pressure over time, frequency,and space.Much of statisticalroom acoustics (SRA) theorycan be developedby applyingrandom walk theoryto classicalroom acoustics. Reverberation time (T•o) controlsthe varianceof reverberantpressure with frequencyat eachroom location. The "reverberationtime-bandwidth" (BTc•o) product controls spatial variance. SRA contradictsthe conventionalwisdom that "hot spots"and "dead spots"indicate poor diffusion, implying instead that spatialvariations are inevitable evenin a perfectlydiffuse field. SPA facilitatednew measurementstandards for estimatingpure tonesound power in reverberation roomsby providingobjective guidance for optimizationof spatialaveraging and estimationof errorbounds. SRA pointsto funda- mentaluncertainties in low-frequencyroom behaviorand connectsroom acousticsto the kinetic theory of gases.Using statistical theoryto solvedeterministic problems of roomreverberation may seemparadoxical if not heretical.Yet SRA continuesto provide unexpectedinsights and discoveries impacting room acoustic thinking and practice. This paper recounts developments from a research participant'sperspective.
TUESDAY AFTERNOON, 14 MAY 1996 MT. RUSHMORE, 4:45 TO 5:45 P.M.
Session2pAAb
Architectural Acoustics: An Afternoon with Leo Beranek
William J. Cavanaugh,Chair CavanaughTocci Associates, Inc., 327F BostonPost Road, Sudbury,Massachusetts 01776
Sponsoredby theTechnical Committee on ArchitecturalAcoustics and The NationalCouncil of AcousticalConsultants
In 1962 Leo Beranekpublished his classicstudy of some55 concerthalls throughoutthe world... "Music,Acoustics and Architecture."This comprehensivecompilation of physicaland acousticaldata on thesehalls as well as scaleddrawings and photographsso thatdirect visual comparisons of onehall with anotherwere possible, proved invaluable to architects,acousticians, musicians,symphony orchestras and others contemplating building new or renovatingexisting halls. Several years ago the Technical Committeeon Architectural Acoustics at theurging of ChristopherJaffe voted to inviteLeo Beranekto updateand reprint the book throughthe Society's"Books" program. Leo Beranek,in his usualscholarly fashion, decided to do more.He hasadded many new halls, omittedothers, and, most significantly,added a totally new sectionreviewing the enormousamount of work that has been ongoingthese past three decades. The TechnicalCommittee on ArchitecturalAcoustics along with theNational Council of Acoustical Consultantsis sponsoring this reception on the occasion of thepublication of thisnew work. Leo Beranek will saya fewwords about his recentstudies reported in the bookand respond to questionsfrom the audience.But mostlythis will be a "firstfor ASA" opportunityto thank the author for his dedication and contribution to our expanding knowledge base on halls for music performance as well as to just plain socializeand talk aboutconcert hall acoustics.
2476 J. Acoust.Soc. Am., VoL 99, No.4, Pt.2, April1996 131stMeeting: Acoustical Society of America 2476
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, 14 MAY 1996 SALON E, 1:25 TO 3:30 P.M.
Session2pBV
Bioresponseto Vibration and to Ultrasound: General Topics
Janet M. Weiscnberger,Chair Speechand Hearing Science,The Ohio State University,1070 Carmack Road, Columbus,Ohio 43210
Chair's Introduction--l:25
ContributedPapers
1:30 2:00
2pBVI. Exposure guidelines for Navy divers exposed to 2pBV3. Information transmission with a multifinger tactual low-frequencyactive sonar. F. MichaelPestorius (Appl. Res. Labs., stimulator. Hong Z. Tan, Nathaniel I. Durlach, William M. ljniv. of Texas,Austin, TX 78713-8029)and MichaelD. CurIcy (Naval Rabinowitz, and Charlotte M. Reed (Res. Lab. of Electron., MIT, SubmarineMedical Res. Lab., Groton, CT 06349-5900) Cambridge,MA 02139)
The informationtransmission capabilities of a multifingerpositional A 30-monthexperimental and modelingstudy was conductedinto the stimulator,called the Tactuator, were explored in a seriesof absoluteiden- effectsof low-frequencyactive (LFA) sonarson Navy divers.453 dives tificationexperiments. Variations in the frequencyof single sinewave using87 subjectswere completedwith one symptomaticevent. A variety stimulievoked three relatively distinct perceptual attributes: smooth mo- of diveequipment, depths to five atmospheres,and three signal waveforms tion(up to about6 Hz), a roughor flutteringsensation (about l0 to 70 Hz), were used.Interim guidancefor exposureto LFA signalswas issuedby the andsmooth vibration (above about 150 Hz). Multicomponentstimuli were U.S. Navy Bureauof Medicineand Surgery.For exposuresto nonimpul- formedby summingsinusolds from eachof thesethree regions, with the sive waterbornesound in the frequencyrange 160-320 Hz, the following intentthat frequency(and amplitude) variations within each region could setof parametersdid notcompromise the safetyof a highlytrained, fit, and be identifiedindependently. Stimulation was applied to eitherone of three informeddiver (divercompromise refers to a diver who couldbecome a digits{thumb, index, or middle)or to all threedigits simultaneously. For casualtyor burdento othersin an operationalsetting): A maximumoverall stimulusdurations of 500 and 250 ms, informationtransfer (IT) was 6.6 SPL of [60 dB for no morethan 100 s continuousexposure on a 50% duty bits(corresponding to perfect identification of 97 stimuli);at 125 ms,IT cycle, with a cumulativeexposure limit of 15 rain/dive-day,a total of 9 was 6.0 bits. Estimatesof potentialIT rateswere obtainedby sequencing days of exposurein a 2-week period.SPL is measuredat the diver's threerandom stimuli and (a) havingthe subjectidentify only the middle location.This guidanceis gcneralizableonly to thosepopulations equiva- stimulusand (b) exlrapolatingthis IT to thatfor continuousstreams. Es- lentin medicalhealth and fitness to U.S.Navy divers. [Work supported by timatedIT rateswere 13 bits/s,and the optimalstimulus presentation rate wasapproximately 3 itemsIs regardless of stimulusduration. This IT rate U.S. Navy.] is roughlythe sameas that achievedby Tadoranusers in tactualspeech communication.[Work supported by NIDCD.]
1:45
2pBV2. A new muitlfinger tactual display. Hong Z. Tan and William 2:15 M. Rabinowitz (Res.Lab. of Electron.,MIT, Cambridge,MA 02139) 2pBV4. Active noise reduction stethoscopy for lung sounds measurement in loud environments. Samir P. Patel, George R. A multifingerpositional display, called the Tactuator, was developed to Wodicka (School of Elec. and Cornput. Eng., Purdue Univ., West •tudy communicalionthrough the kinestheticand vibrotaclileaspects of Lafayette,IN 47907-1285),and Matthew G. Callahan (Univ. Res. the tactualsensory system of the hand.The displayconsists of threeinde- Engineers& Assoc.,Inc., Acton,MA) pendentsirigle-point actuators interfaced (individually) with the fingerpads of the thumb,the indexfinger, and the middlefinger. Each acluator utilizes Auscultationof lung soundsin vehiclessuch as an ambulanceor air- a disk-drivebead-positioning motor augmented with angular position feed- craft is unachievablebecause of high noiselevels. Also, the bandwidthsof backfrom a precisionrotary variable differential transformer (RVDT). A lungsounds and vehicle noise typically have significant overlap, limiting floating-pointDSP systemprovides real-time positional control, using po- the utilityof bandpassfiltering. In thisstudy, a passivelyshielded stetho- scopecoupler with one microphone to measurethe (noise-corrupted) lung sitionand derived-velocityfeedback. Stimuli from thresholdto about50 soundsand anotherto measurethe ambientnoise was constructed.Lung dB SL can be deliveredthroughout the frequencyrange from near dc to soundmeasurements were performed on a healthysubject in a simulated above300 Hz, therebyencompassing the perceptualrange from gross 1JSAF C-130 aircraft environment within an acoustic chamber at noise motionto vibration.Actuator frequency and stepresponses are well mod- levelsranging from g0 to 100dB SPL.Adaptive filtering schemes using a eledas a second-orderlinear system. Distortion is low allowingdelivery of leastmean squares (Ires) and a normalizedleast mean squares (nlms) arbitrarystimulus waveforms, e.g., 25-ram low-frequencymotion with approachwere employed Io extractlung sounds from the corrupted signal. superimposedhigh-frequency vibralion. System noi•e and interchannel Up to 25 dB of noisereduction over the 100-600 Hz frequencyrange was crosstalk are alsosmall. As one exampleof behavioralperformnonce veri- achievedwith the lms algorithm,with the more complex hims algorithm fication, absolutethre.•holds measured with the stimulatorare in general providingfaster convergence and up to 5 dB of additionalnoise reduction. agreementwith referencevalues. Overall, the Tactuator accurately follows These findings indicate that a combinelionof active and passivenoise its drive waveformsand is well suitedfor a variety of multifingertactual reductioncan be used to measureclinically useful lung soundsin high perceptualstudies. [Work supported by NIDCD.] noiseenvironments. [Work supported by US Air Force.]
2477 J. Acoust.$oc. Am., Vol.99, No. 4, Pt. 2, April1996 131st Meeting:Acoustical Society of America 2477
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 2:30 3:00
2pBVS. Echo-based neonatal breathing tube monitoring system. 2pBV7. A modal characterization of the ovine head. Teresa A. Jeffrey P. Mansfield,George R. Wodicka (Schoolof Elec. and Comput. Whitman,Mark T. Morgan (Schoolof Agriculturaland Biological Eng., Eng. and HillenbrandBiomedical Eng. Ctr., PurdueUniv., West Lafayette, PurdueUniv., West Lafayette,IN 47907-1146),and GeorgeR. Wodicka IN 47907-1285), and Daniel C. Shannon (MassachusettsGeneral (PurdueUniv., WestLafayette, IN 47907-1285) Hospital,Boston, MA 02114) Althoughthe vibrationalresponse of the head has been observedto A deviceto monitorthe positionand patencyof neonatalbreathing correlatewith intracranialpressure when measurements are madedirectly tubes(endotracheal tubes, ETI •) was developedbased on a pulse-echo on the skull [M. Stevanovicet aL, Ann. Biotaed.Eng. 23, 720-727 techniqueoriginally employed in a systemfor adultbreathing tubes [J.P. (1995)],the effect of theextracranial tissues of an intacthead has only Mansfieldand G. R. Wodicka,]. SoundVib. 188(2), 167-188 (1995)]. A beenhypothesized. In this study,the modalcharacteristics of the freely 100/zs durationsound pulse is emittedinto the neonatalETT via a wave vibratingovine headunder various stages of intra- and extracranialtissue tubecontaining a miniaturesound source and a miniaturemicrophone. The removalwere determined. Frequency responses from 20 to 2000 Hz were microphonedetects echoes from acoustic impedancechanges arising measuredusing an accelerometerand impacthammer at 32 siteson 5 largely from changesin cross-sectionalarea within the ETI' lumen and intactovine heads,and after progressiveremoval of the jaw, intra- and airways.The delaysand amplitudes of echoesfrom obstructions within the extracranialtissues, and finally on the boiledand dried skull. lntra- and ETT are used to estimatetheir respectivelocations and sizes.An echo extracranialtissues increased modal damping and decreasednatural fre- arisingfrom the ET!' tip providesan estimateof the cross-sectionalarea quencies.Dried skullsexhibited as many as 5 lightly dampedresonances just beyondthe tube tip andis usedto distinguishbetween proper tracheal with the lowestoccurring around 1 kHz, whereasonly 2 heavilydamped and erroneousbronchial or esophagealintubations. Determination of tra- resonanceswere evident prior to boiling.The firstresonance for the heads cheal positionis accomplishedby trackingthe delay of a characteristic at variousstages of tissueremoval occurredbetween 200 and 400 Hz and echo which arisesfrom the airways.During intubatiouin five anesthetized similar modeshapes between heads were foundat this lowestresonance as rabbits,the devicetracked changes in ETI' positionwith an accuracyof comparedby the Modal AssuranceCriterion. As natural frequenciesin- 1-+ 1.7 mm (mean-+s.d.)over 188 measurements,which is adequatefor creased,the modesbecame more complex, resultingin dissimilar mode use in even the smallest infant. shapesbetween heads. [Work supportedby NSF.]
3:15 2:45 2pBV8. Measurements of the effect of polypropylene vials on 2pBV6. Spatial information in simultaneous multimicrophone ultrasoundpropagation. RobinO. Cleveland,Michalakis A. Averkiou, recordings of thoracic sounds. Martin Kompis and George R. LawrenceA. Crum (Appl.Phys. Lab., Univ. of Washington,Seattle, WA Wodicka (Schoolof Elec. and Cornput.Eng., PurdueUniv., West 98105), and ]ames A. McAteer (Indiana Univ. Schoolof Medicine, Lafayette,IN 47907-1285) Indianapolis,IN 46202-5120) An algorithmfor thereconstruction of thedistribution of soundsources Polypropylenevials are commonly used in in vitroexperiments to hold within the thorax was developed.For any point within the thorax,the cell preparationsthat are exposedto ultrasound.The vial has an acoustic algorithmtests the hypothesisthat it containsthe only relevantsource to impedancevery close to water, in which casethere shouldbe little trans- explain a given set of simultaneousmeasurements on the chest wall. A missionloss as soundpropagates into the vial. Measurementsof the acous- hypotheticalsource signal is calculatedby a least-squaresestimation pro- tic field withinpolypropylene vials have been carried out using both pulsed cedarefor all pointsI cm aparton a equallyspaced grid overlyingthe medicalultrasound and lithotripter shock waves. It hasbeen found that for thoracicvolume. The explainedfraction of the totalsignal variance of all certainorientations of theacoustic field andvial thereis significantloss of microphonesis thendisplayed as a functionof spacein a 3-dimensioual pressureamplitude within the vial. In particular,sound that entersthe vial grey-scalecoded image. The algorithmwas appliedto simultaneouslung throughthe round, hemispherical end is attenuatedand distorted. Hot and soundrecordings with eightmicrophones from two healthymale subjects. cold spots within the vial are also measured.When the roundedend is Preliminaryfindings suggest that inspiratorysounds are producedmore replacedwith a fiat surfacevery little distortionand attenuationof the peripherallyin the thorax,while cxpiratorysounds originate more cen- waveformoccurs. The distortioninduced by the roundend is apparently Wally.Some of the imagesdepict features which correlate with anatomical dueto refractionintroduced by thevial--the speedof soundin polypro- structuressuch as the largeairways, the he0az,or duringthe processof pyleneis about1.7 timesthat of water.A simpleray analysisindicates the swallowing,the esophagus.A mechanicallung modelis beingdeveloped presenceof hotand cold spots within the vial in qualitativeagreement with to investigatethe significanceand reproducibility of theseimages features. observations.These results indicate that cell injuryexperiments may be [Worksupported by SwissNational Research Foundation, Roche Research dependenton the vial orientation.[Work supported by NIH andthe ASA Foundation,and NSE] Hunt Fellowship.]
2478 J.Acoust. Sec. Am., Vol. 99, No. 4, Pt.2, April1996 131stMeeting: Acoustical Society of America 2478
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, 14 MAY 1996 NATIONAL PARKS, 2:00 TO 4:45 P.M.
Session2pEA
Engineering Acoustics:Surface Acoustic Wave (SAW) Devices
Harold C. Robinson, Chair Code 2131, Naval UnderseaWarfare Center, New LondonDetachment, New London,Connecticut 06320
Invited Papers
2:00
2pEAl. Typesand propertiesof surfaceacoustic waves. HaroldC. Robinson (Naval UnderseaWarfare Ctr., New London.CT 06320)
Surfaceacoustic waves (SAWs) are used for a widevariety of signalprocessing and sensing applications at highfrequencies. SAW devicesare attraclive for theseapplications because of theirsmall size and low costrelative to manycompeting technologies. However, SAWs are physicallyquite different from the acousticwaves encountered in sonarand medicalultrasorties. In addition,the family of surfaceacoustic waves is quite diverse,with each type of wave having unique electricaland mechanicalcharacteristics. This presentationwill describethe physicalproperties of surfaceacoustic waves and delineatewhat distinguishesSAWs from othertypes of elasticwaves. The simple exampleof an isotropicelastic materialwill be examinedin somedetail to illustratemany of the fundamentalconcepts of SAWs. Methodsof generatingand detectingSAWs usedin deviceapplications will be shown.A simple interdigitalSAW devicewill be describedin termsof its composition,design, and electricaland mechanicalproperties. A brief historicaloverview on the developmentof surfaceacoustic wave deviceswill alsobe presented.
2:30
2pEA2. Overviewof SAW materials. ArthurBallato (US Army Res.Lab., AMSRL-PS, Fort Monmouth, NJ 07703-5601)
There is now a rich varietyof piezoelectricmaterials available for surfaceacoustic wave applications.These include crystals in symmetryclasses mm2, 32, 3m, 4mm, 6mm, and493m. Classes6ram and 4•3m includemost of thebinary semiconductors, such asgallium arsenide and related alloys, making integrated acoustic/electronic devices possible. Depending upon use. the SAW substrate materialmay be chosento havecerlain combinations: piezocoupling, temperature coefficient of frequencyor delay,small coupling to bulkmodes, tow sensitivity to accelerationor thermaltransients, high acoustic Q, smallpower flow angle, etc. In thispaper, these and othercriteria are discussedbroadly, with illustrationsof pertinentmaterials and orientations. Also givenare recommendationsof substancesfor whichthe materialconstants are well enoughknown to be practical,as well as indicationsfor necessaryfuture work in growthand characterization. A broadband equivalent electrical network for SAW propagationis presented,by meansof whichthe appropriatematerial parameters may be extractedfrom networkanalyzer measurements. The circuitcan alsoserve to representthe salientfeatures of devicesin their working environments.
3:00
2pEA3,Surface acoustic wave device fabrication. DonaldC. Malocha (Elec.and Cornput. Eng. Dept., Rm. 407, Univ.of Central Florida, Orlando, FL 32816-2450) Manyfrequency control operations for wirelessand satellite communication systems are provided by acousticsolid-state devices in theoperating frequency range from 10 MHz to 3 GHz.Surface acoustic wave (SAW) device technology isa keytechnology because it is solidstate, monolithic, high performance,and low cost.An importantparameter is the versatilityand simplicityin device fabricationsince many techniques developed by the integratedcircuit industry can be applied.
3:30-3:45 Break
3:45
2pEA4.Surface acoustic wave microsensors. John E Vetelino (Lab.for SurfaceSci. and Techno[., Sawyer Res. Bldg., Univ. of Maine, Orono,ME 04469)
Surfaceacoustic waves (SAWs) excited on thesurface of piezoelectriccrystals form Ihe basisof a familyof microsensorsthat is sensitive.portable, cheap, and small. These microsensors canbe used in a widevariety of applicationsto sense low levels of gases, physicalquantities such as mass,temperature, pressure, flow and humidity, biological processes, corrosion, ions and particulate matter, anda varietyof mechanicaland electrical quantities. In contrastto othermicrosensor technologies. SAW microsensors can sensitively detectboth electrical and mechanical phenomena. This is dueto the factthat the SAW hasboth mechanical and electrical fields. In thoseapplications requiring sensitivity, such as gas sensing and biosensing, the selectivity is providedby a receptorfilm appliedto the piezoelectricsubstrate. In thispaper different types of SAWsare described and prototype sensing geometries are presented. Particular attentionis devotedto oneof the mostcommon SAW microsensorapplications, namely. gas sensing. Finally, results obtained using SAW microsensorsin a varietyof applicationsare presentedand discussed.
2479 J. Acoust.Soc. Am., Vol.99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2479
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 4:15
2pEA5. A reviewof progressin acousticcharge transport technology. William D. Hunt (Schoolof Elec. and Comput.Eng., GeorgiaInst. of Technol.,Atlanta, GA 30332-0250)
Acousticcharge transport (ACT) devices are essentially charge coupled devices for whichthe potential propagating with a surface acousticwave (SAW) in a piezoelectricsemiconductor traps and transports charge. In thispaper a physicaldescription of device operationfor which both acoustic and electronic attributes play a keyrole is given. Next, the various acoustic and electronic modeling toolsthat have been developed to aidin thedesign of ACT deviceswill bediscussed. There have been several architectures which have beenreported to dateand the virtues of theseapproaches will be compared.There will be a discussionof someof theproblems that havekept the technology from gaining widespread acceptance and some predictions of theareas of researchwhich will be themost promising.
TUESDAY AFTERNOON, 14 MAY 1996 REGENCY A, 1:00 TO 2:00 P.M.
Session2pMUa
Musical Acoustics:Distinguished Lecture
Uwe J. Hansen, Chair Departmentof Physics,Indiana State Universi.ty,Terre Haute, Indiana47809
Invited Paper
1:00
2pMUal. Nonlinearityand the soundsof musicalinstruments. NevilleH. Fletcher (AustralianNatl. Univ.,Canberra, Australia)
Musicalinstruments can be classifiedinto two groups--thosethat have a continuousenergy input and produce a sustainedsound, and thosethat have an impulsiveenergy input and producea transientdecaying sound. Instruments of the first group,which includes violins,flutes, clarinets, trumpets, etc., can be describedas "essentiallynonlinear," by which it is meantthat their musicaloperation dependscritically upon the presence of nonlinearity,and without it theywould scarcely sound at all. The transientor percussivegroup of instruments,which includespianos, guitars, bells, gongs,and cymbals,on the other hand,can be describedas "incidentally nonlinear"implying that, while nonlinearity may influence their sound, its presenceis by no meansessential. Paradoxically, inadequate nonlinearityin a sustained-toneinstrument leads to complexbehavior, while complexity in a transientinstrument is enhancedby strong nonlinearity!This talk exploressome of thesematters in a simplephysical way, with demonstrationsfrom particularlyinteresting instrumenttypes.
2480 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2480
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, 14 MAY 1996 REGENCY A, 2:10 TO 4:25 P.M.
Session2pMUb
Musical Acoustics:General Topics:Mostly Perception
Ian M. Linderaid, Chair Division of Science,Northeast Missouri State University,Barnett Hall, Kirksville,Missouri 63501
ContributedPapers
2:10 whicha performed(external) rhythm serves as driver,and an internal "attentionalrhythm" is modeledas a nonlinearlydriven oscillator. Next, a 2pMUbl. Pitch perception of spectrally dense musical chords in a coupledtwo-oscillator network, designed to simulatethe perceptionof highly reverberantchurch. lax M. Linderaid (Div. of Sci., Northeast multiplebeat periods (meter), is introduced.The one- andtwo-oscillator Missouri State Univ., Kirksville, MO 63501) models'ability to track beatsand recovermeter is testedin pianoperfor- Pitchchanges perceived across the transitionfrom a drivenroom sound mancesof Bach'sTwo-Part Inventions. The coupledoscillator network not field to a freely decayingroom soundfield were studiedin a subjective only extendsthe modelto the perceptionof •neter,but alsoinfluences the experiment.Speclrally dense organ chords were recordedin a churchand abilityof eachcomponent oscillator to tracka componentperiodicity in the latergated to providesamples from both the driven and the decayingsound externalrhythm. The ability of the networkto recoverother typesof fields.Terhardt's dynamic pitch algorithm was usedto analyzethe chord musicalinformation, such as phrasestructure, from performancetiming is samplesfor comparisonwith experimentalresults. On average,when discussed.[Work supportedby NSF SBR-8920230and NIMH R29- choosinga lower octavesinusold for tuning,subjects tuned flatter than MH45764.] whenchoosing a higheroctave. This resultis consistentwith the predic- tionsof Terhardt'salgorithm. Second, there was a consistenttrend to per- 2:55 ceivethe reverberantsound field an averageof about20 centsflatter than the correspondingdriven sound field. This effectis not predictedby Ter- 2pMUb4. Musical stability and melodic implication. William Forde hardt'spitch model. [Work supportedby the ASA's Hunt postdoctoral Thompsonand Murray Stainton (Atkinson College, York Univ., ON, fellowshipof 1987-88.] Canada) Five perceptualprinciples of melodicimplication, derived from Nar- 2:25 mour's (1990, 1992) "implication-realization"theory of melody,were evaluatedin an analysisof Europeanfolk songs.The principlesapply only 2pMUb2. Integrality of first inversionC-major chord components. to unstable or unclosed melodic conditions, and define how such condi- BarbaraE. Acker and Richard E. Pastore (Dept. of Psych.,SUNY, tionsinitiate processes of patternrecognition which then generate expec- Binghamton,NY 13850) tationsabout the propertiesof subsequentnotes. For instance,the principle of proximitystates that unstableevents generate an expectationthat the Previouswork [Acker and Pastore, Percept. Psychophys. (in press)] nextnote will be proximalin pitch.Musically stable and unstableevents usinga discriminationversion of the Garnerparadigm found the E and G were identifiedin over 700 melodies,using criteria basedon metricstress, frequenciesof a root positionC-major chord to be integral,with both tonality,and duration. For each event, the next note (the continuation note) frequenciesexhibiting significant redundancy gains in the correlatedcon- was recorded.Multinomial loglinearanalysis assessed whether the five dition, but with the E exhibilingless interference in the orthogonalcondi- principles,separately or in combination,could predict the frequencywith llon than the G. This findingraised the questionof whetherattention was which different continuation notes followed different conditions of stabil- betterallocated to the E frequencyspecifically, or if it wasa functionof the ity. For continuationnotes following unstableevents, statistical support middle spectral location. The current work addressesthis questionby wasfound for all principles.The link betweenmusical stability, melodic evaluatingdiscrimination of chordcomponents in a first inversionchord, expectation,and compositionis discussed. wherethe E is the lowestfrequency component instead of the middle component.Subjects completed fixed, correlated, and orlhogonal discrimi- nationtasks for eachfrequency. Replicating the earlierresults, both fre- 3:10 quenciesexperienced significant redundancy gains in the correlatedcon- 2pMUb5. Instrument-specificconstraints on musical performance: dition, and the E frequencyagain exhibitedless interferencein the PlayingIhe pianoand lhe guitar. TimothyM. Walker (Dept.of Psych., orthogonalcondition. These results will be discussedin termsof attention Ohio StateUniv., Nell Ave., Columbus,OH 43201) beingmore easily allocatedto the E frequencyspecifically, regardless of spectrallocation. [Work supported by AFSOR.] Kendalland Carterette (1990) proposea chainof musicalcommunica- tion similarto linguisticcommunication, whereby composers, performers, and listenersall sharesome amount of musicalknowledge. Although the 2:40 authorsemphasize the extentIo which informationis communicated,there are also importanttransformations which take place.The physicalcon- 2pMUb3. Nonlinear dynamicsof rhythm perceptionin performed straintsof an instrumentmay play a significantrole in the interpretive music. EdwardW. Large (Inst. for Res. in Cognit. Sci., Univ. of processby operatingas musicalfilters. Improvisation is consideredas a Pennsylvania,3401 Walnut St., Philadelphia, PA 19104-6228} and taskin whichall threelinks in the communicativechain (composer, per- CarolinePalmer (Ohio StateLlniv., Columbus, OH 43210) former.and listener}are simultaneouslyrepresented by a singlemusician. Listenersare readilyable to identifyand tracknearly periodic compo- An experimentwas conducted in whichparticipants were asked to perform nentsin complexauditory rhythms such as music,despite the largetem- improvisationson a guitaror piano,each of whichfunctioned as an MIDI poralmodulations that commonly exist in musicperformance. The modu- instrument.The soundedtimbre was independentlyvaried, to produceei- lationsthat performersintroduce, however, often communicatemusical thera guitaror a pianosound. Participants displayed different patterns of informationsuch as melody, phrasestructure, and meter.A dynamical key choiceand note usagedepending upon which instrumentthey were systemmodel of beattracking in musicperformance is firstdescribed, in playing,suggesting that the physicalconstraints of the instrumentinflu-
2481 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2481
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 enced their performance.Participants also employedexpressive guitar mothershad grown up in diversegeographical regions, including England, pitchbends only in the guitartimbre. suggesting that higher-levelknowl- the Europeancontinent, and variousparts of the United States.The per- edge of instrumentcharacteristics. as well as externalphysical constraints, ceptionsof all the subjectscorresponded more closely to thoseof their caninfluence musical performance. [Work supported by NIMH grant1t29- respectivemothers than to the averageof all the mothers;this effect was MIt45764,] highlysignificant statistically. Implications of thesefindings are discussed.
3:25 3:55
2pMUb6. Rate change effects on the performance of musical 2pMUb8, Directed attention and perceptionof frequency changes. sequences,Rosalee K. Meyer, CarolinePalmer (Ohio State Univ., BarbaraE. Acker and Richard E. Pastore (Dept. of Psych.,SUNY, Columbus,OH 43210),and Leonard B. Meyer (Univ.of Pennsylvania) Binghamton,NY 13902-6000)
Changesin presentationrate can causeperceptual reorganization of What role doesattention play in the perceptionof componentswithin rhythmic structurein music. This finding is extendedto music perfor- a melody'?.A paradigm used by Palmerand Holieran [Percept. Psychophys. mance. One music-theoreticexplanation suggests that larger-scalestruc- 56(3), 301-3 i 2] providesa basisfor addressingthis question. Their study turessuch as meter are perceptuallyprominent at fast ratesand smaller- investigateddifferent influences on the perceptionof pitch alterationsin scalestructure such as segmentationof eventsequences into groupsare three-voicedmusical passages. where subjects first learned a four-measure pereeptuallyprominent at slow rates.In contrast,theories of motorpro- standard,then completed a same/differenttask. "Different" passageswere grammingpredict that event durations during performance should remain constructedby alteringthe originalstandard, with a harmonicallyrelated proportionallyconstant across rate changes (relational invariance). In an (HR) or unrelated(Hi J) frequencychange made in the lowest,middle. or initial study,pianists performed the samemusical sequence at different uppervoices of the musicalpassage. Results indicated that HR changes rateswith differentgrouping structures. Interactions of groupingand se- were lessdetectable than HU changesand were the leastdetectable in the quencerate on componentnote durations support the music-theoreticex- middle voice.The currentstudy uses the sameprocedures and musical planationof perceptualreorganization and suggestwhy relationalinvari- materialsas thePalmer and Holleran work, but providesthe subjectswith ancefails in complexbehaviors. However, the role of tactus(pemeptua!!y cuesindicating which frequency region might contain the alteration(low, prominentbeat level) was not considered in thisstudy; perception of tactus medium,or high).Results will be discussedin termsof the role directed differs acrosspresentation rates. The interactionof tactuswith rate changes attentionplays as a functionof harmonicrelationship and frequencyre- in perceptualreorganization of musicalstructure is investigatedin a per- gion. formantetask. It is predictedthat higher tactus levels (longer beat dura- tions)are emphasized (more accurate, less variable) at fastrates and lower tactuslevels (shorter durations) are emphasized at slowrates. [Work sup- 4:10 portedby NIMH R29-MH45764.] 2pMtJb9. Design and measurementsof variably nonuniform acoustic resonators.Bruce Denardo and Miguel Bernard (Dept.of Phys.and 3:40 Astronomy,and Natl. Ctr. for PhysicalAcoust., Univ. of Mississippi, University,MS 38677) 2pMUb7. Mothers and their children hear a musical illusion in strikingly similar ways. Diana Deutsch (Dept. of Psych.,Univ. of The design, construction,and acousticalmeasurements of resonators California, San Diego, La Jolla, CA 92093} with nonuniformcross-sectional areas that are easilyaltered to yield dif- ferentresonance frequencies are described.These resonators are usefulas A two-tonepattern, known as the tritoneparadox, has certaincurious educationaldemonstrations of symmetrybreaking and of an efl•ct of non- properties.It is heard as ascendingwhen played in one key, yet as de- uniformityupon standing waves, and have been previously demonstrated scendingwhen playedin a differentway. Further,when the patternis andexplained lB. Denardo,J. Acoust.So:. Am, 95, 2935(A)(1994), and played in any one key it is heardas ascendingby somelisteners but as B. Denardoand S. Alkov,Am. J. Phys.62, 315-321 (1994)].Resonators descendingby others.Perception of thispattern has been found to varyin thatyield two, three,and four pitchesare considered,where the relative correlationwith thegeographical region in whichthe listenergrew up, and frequenciesare designedto correspondto musicalintervals. Agreement is also with the pitchrange of the listener'sspeaking voice [D. Deutsch, within 2% in all cases and 1% for most. The data reveal a breakdown of the Philos.Trans. R. $oc. LondonSet. B 336, 391-397 (1992)].A striking theory,which is shownto be a resultof additionalkinetic energy, and thus correlationis here reportedbetween how a listenerhears this patternand effectiveinertia, near a discontinuityin cross-sectionalarea. The dataalso how his or her motherhears it. Fifteensubjects (ten childrenand five reveal that an appropriateend correctionfor this caseis not that for a adults)were studied.The subjectswere all Californians;however their thin-walledtube but. rather,an infiniteflange.
2482 J. Acoust.Soc. Am., VoL 99, No.4, Pt.2, Apdl1996 131stMeeting: Acoustical Society of America 2482
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, 14 MAY 1996 REGENCYA AND B, 5:15 TO 6:30 P.M.
Session2pMUc
Musical Acoustics:The Ohio State University Wind Ensemble
JamesM. Pyne, Chair Schoolof Music,Center for CognitiveScience, The Ohio State University, 1866 College Road, Columbus, Ohio 43210
Chair's !ntroduction--5:15
lnvRed Paper
5:20
2pMUcl. The OhioState University Wind Ensemble.Gary Lewis and Kathleen Gatdiner (School of Music,Ohio State Univ., 1866College Rd., Columbus,OH 43210) The OhioState University Wind Ensemble musicians are the finest wind and percussion performers, both graduate and under- graduate,atthe Ohio State University. These gifted young players will present an exciting program that displays their remarkable range of musicaland dramatic capability. Youthful and dynamic, conductor Gary Lewis is in hispremiere season as OSU director of bands. He comesto OSUfrom the University of Michigan,where he served as director of theMichigan Marching Band and as conductor of theWind Ensemble and Contemporary Directions Ensemble. Professor Lewis is activeas a guestconductor throughout the United Statesand is highly respected in the realm of bothwind ensemble and orchestral conducting. Clarinet soloist Kathleen Gardiner, holds a prestigiousResearch and Graduate Council Fellowship and is a doctoralcandidate at OSU. She was the first place winner of the InternationalClarinet Association solo competition in 1994and the Eastman School of Musicconcerto competition in 1993.As a professionalperformer Ms. Gardinerserves as principal clarinet of thePro Musica Chamber Orchestra.
TUESDAY AFTERNOON, 14 MAY 1996 MT. RUSHMORE, 1:00 TO 3:35 P.M.
Session2pNS
Noise,Architectural Acoustics, Structural Acoustics and Vibration,and EngineeringAcoustics: Curt Holmer Retrospective
David Lubman, Cochair David Lubmanand Associates,14301 Middletown Lane, Westminster,California 92683
RichardH. Lyon, Cochair RH LyonCorp, 691 ConcordAvenue, Cambridge, Massachusetts 02138
Chair's Introduction--l:00
Invited Papers
1:05 2pNS1.Aconsultant foracoustical product breakthroughs•A tribute. JohnW. Kopec (RiverbankAcoust. Labs.(RALT•),1512 BataviaAve., Geneva,IL 60134) Thestaff at theRiverbank Acoustical Laboratories (RAL TM) in Geneva,IL is oftenasked to recommendanacoustical consultant fora myriadof acousticalrelated projects. In order to avoid any unfavorable backlash situations, thestaff has to be as certain as possiblethat they recommend a consultant who will successfully fulfill the request at hand. To assist in theselection process a three-level-typelistof tasks, including thenames ofvarious acoustical consultants thatmight fulfill these tasks, was compiled. Level threeincluded the names of acousticalconsultants that possibly could fulfill, perhaps, one of themore demanding kinds of requests, whichwas the need for anacoustical consultant that could provide the design of anacoustical breakthrough product. Curt Holmer fulfilledthat request three times, and because of that he had earned a well-deserved place on the list of outstandingacoustical consultingaccomplishments thatat thetime of theiroccurrence provided an acoustical breakthrough.
2483 d.Acoust. Soc. Am., Vol. 99, No. 4, Pt.2, April1996 131stMeeting: Acoustical Society of America 2483
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
2pNS2. Curt Holmer in retrospect. G. Maidanik (David TaylorModel Basin,NSWC, Bethesda,MD 20084-5000)
WhenCurt joined BBN I had'already left, nonethelessat ASA andother societies' meetings we metand discussed many scientific issues,past and present. His interestin statisticalenergy analysis (SEA) was particularly intense, but not to theexclusion of manyother interestingtopics in the analysisof structuralacoustics and noisecontrol. He was a patientlistener and a critic of note, but always gentleand erapathetic. I enjoyedand valuedhis companyand, as manyothers who knew him, will continueto misshis presence.
1:55
2pNS3. "Why don't we make the membrane loose?"Twelve years of noisecontrol foams. J. SmartBolton (1077 Ray W. HerrickLabs., School of Mech. Eng., PurdueUniv., WestLafayette, IN 47907-1077)
Curt Holmer was well knownto me while I was a graduatestudent in Englandthrough the chapterin Noiseand VibrationControl that he co-wrotewith IstvanVet. In a book that may be the mostcommonly referred to on acoustics,his was the chapterthat I found mostuseful for bothits qualitativeand quantitative insights. When I cameto Purduein 1984 it was a pleasantsurprise to find boththat Curt wasworking nearby in Indianapolisand that he had an interestin noisecontrol foams of the type thatI had studiedduring my Ph.D. I soonfound an opportunityto invitemyself down to meethim at EAR, and,like manyothers before, discovered him to be a graciousand generous host. We becamegood friends, and over the nextdecade he activelyencouraged my interestin boththeoretical andpractical aspects of noisecontrol foams (even though when we firstmet he gently revealed that EAR wasalready selling a product basedon what I hadthought was my own "revolutionary" insight: see title). In thispresentation, progress in thearea of foammodeling over the time that I knew Curt will be reviewed.
2:20
2pNS4. The acousticsof structureswith fuzzy joints. RichardH. Lyon (Rid Lyon Corp.,Cambridge, MA 02138)
Curt Holmerwas always interested in thepractical applications of statisticalenergy analysis, and the authorhad many discussions with him regardingits uses,and areasof transitionto deterministicanalysis. In someof the latestdiscussions, the topic of the "mid-frequencyrange" dominated, referred to by the authoras "the awkwardzone." In thistransition range between deterministic and fully probabilisticmodels, the greatestuncertainty may he in thejoints--their actual location, and their rigidity. This suggestsa hybrid approach,in whichthe substructures are treated as deterministic, and the joint locationsand rigidities are uncertain, or in popularterms, fuzzy.This approachis exemplifiedby thejoining of two platesby a link havinga locationand stiffness that are variable over a small range.The resultsof theanalysis support such an approach,in thatthey show the kind of transitionthat has been noted in theawkward ZOne.
2:45
2pNS5.Evaluation of a techniqueto identifymodels of modesin nonlinearstructures. S.A. McCabeand P. Davies (RayW. HertickLabs., School of Mech.Eng., Purdue Univ., West Lafayette, LN 47907-1077) Interactionsbetween modes in nonlinearstructures can lead to situationswhere, for thesame excitation, different responses may be observed.The observedresponse will be a functionof the system,of theexcitation, of initialconditions, and of theeffects of small perturbationsto thesystem. Some responses may be observedmore often than others. When the morerarely observed responses are perceivedas problemsituations, it is oftenfrustrating to demonstratethat the problemexists, because it is difficultto controlthe test sufficientlyto repeatedlyobserve the behavior.Analysis of systemmodels can be usedto identify underwhat conditionsthese responsesmay occur, and indicate how theregion where such responses are possible may be approached.In real systems,the model structurefor the systemhas to be identified,which may be an affirmationof a theoreticalmodel structure, and the parametersof these modelsestimated. Described in the presentationare the resultsof usinga systemidentification technique to constructmodels relating the excitationto the responseof two interactingmodes in a thin plate under tension.
3:10
2pNS6.High frequencymodeling of vehiclenoise performance of aluminumbody structure. JamesJ. Lee,Curt Holmer, and Mark J. Moeller (FordMotor Co., Adv. Eng. Ctr., Dearborn, MI 48121) Thispresentation is dedicated to CurtHolmer's contribution to acousticsat FordMotor Co. The presentation material is bas• on the workhe wasinvolved with duringthe lastpart of hislife. The resultsof the 1992Tanms SEA modelare used to assessthe effect of analuminum body structure. The noise performance comparison includes airborne and structure-borne paths. The effect of structural dampingis also simulated.
2484 J.Acoust. Soc. Am., Vol. 99, No.4, Pt.2, April1996 131stMeeting: Acoustical Society of America 2484
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, 14 MAY 1996 REGENCY C, 1:00 TO 4:30 P.M.
Session2pPAa
PhysicalAcoustics and Bioresponseto Vibration and to Ultrasound:Workshop on TherapeuticApplications of Medical Ultrasound II
Jeffrey B. Fowlkes,Chair DepartmentofRadiology, University ofMichigan Medical Center, Kresge III R3315,Box 0553, Ann Arbor, Michigan 48109
This Workshopis an attempt to bring a "small meeting" environmentinto a big meeting. In addition to the tutorial and special presentationsoutlined below and in the relatedsessions (2aPAa, 3aPAa); there will be significantparticipation by otherworkshop attendees;discussion among participants is a major objectiveof this program.Therefore, a specifictimetable will not be followed during the workshop. Registrationfor the tourto IndianaUniversity School of Medicineto be heldon Wednesdayafternoon (see Session 3pPA, page 2527) will be held at this session.Space on the tour is limited.
Chair's Introduction--l:00
Invited Papers
2pPAal. The demographicsof cavitation produced by medical ultrasound. RonaldA. Roy (Appl. Phys. Lab., Univ. of Washington,Seattle, WA 98105)
A frequentconsequence of moderate-to-high intensity ultrasound is thenucleation and proliferation of acousticcavitation activity. Nucleationrefers to the formationof a gas/vaporbubble resulting from acousticstress. Cavitation activity is the subsequentenergetic motionof thesebubbles, and the associatedmechanical and thermal effects. The processis very nonlinear.It is appropriateto view the familyof cavitationas occupied by distinct,yet relatedphenomena. For example, if onedrives a bubbleat moderateamplitudes, stable motionresults accompanied by fluid microstreaming.If the samebubble is drivenhard, explosive growth is followedby inertial collapse,together with theformation of shockwaves, free radicals,etc. When assessing the likelihoodof a mechanicalbioeffect, one must considerthe characteristicsof the cavitation field, which can be estimatedknowing the propertiesof the medium, and the propertiesof the soundfield. A tutorialdescription of basiccavitation dynamics is presented.Attention is givento thoseaspects of bubble motion that are relevant to medical ultrasound conditions. Associated mechanical and thermal effects are discussed, and the relationshipsbetween the characteristics of the soundfield and the expected cavitational response of the mediumexplored. [Work supportedby NIH GrantPOI DK43881-01.]
2pPAa2.Resonant bubbles and bioeffectsmechanisms. Edwin Carstensen (Rochester Ctr. for BiomedicalUltrasound, Univ. of Rochester,Rochester, NY 14627)
2pPAa3.Potential applications of acoustic generation of arterialmicrobubbles. P.L. Carson,J. B. Fowlkes,E. A. Gardner,al M. Bruce,and J. M. Rubin (Dept.of Radiology,Univ. of MichiganMedical Ctr., Ann Arbor, MI 48109-0553) With intense,focused ultrasound pulses it is possibleto generatemicrobubble boluses in the arterialsystem with potential diagnosticand therapeutic uses. Arterial microbubbles have been generated recently in flowingwhole blood in vitrowith 725 kHz ultrasoundpassing through canine tissues simulating human transcutaneous generation. Similar generation was reported previously [J. A. lveyet al., UltrasoundMed. Biol. 21,757-767 (1995)]from interoperative, in vivo exposures at 1.8MHz andat higherintensities. If biologicaleffects can be controlled acceptably, knowledge of ultrasonicbioeffects will beenhanced. Short boluses of ultrasonically imageable,less than 40 micronbubbles, generated in selectedarteries, might be usablefor diagnosisand monitoring of those macrovascularand perfusion abnormalities which currently are evaluatedmore slowly and, presumably, expensively. Very sparse distributionsof 30 to 40 micronbubbles should provide point beacons with whichto refocusultrasound beams for highresolution imagingand treatment through aberrating tissues including the skull.Identification of feederarteries to anddisruption of flow to therapeutictargets should be achievable toenhance chemical or ultrasonic therapy. [Work supported in part by USPHS grant No. 2ROI DK 42290from the Nat'l lnst. Diab., Digestive and Kidney Disease.] alCurrent address: Acuson, Inc., Mountain View, CA.
2pPAa4.Intestinal hemorrhage from exposureto pulsedultrasound and lithotripterfields, DianeDalecki, Sally Z. Child, CarolH. Raeman,David 1• Penney,and Edwin L. Carstensen(Rochester Ctr. for BiomedicalUltrasound, Univ. of Rochester, Rochester,NY 14627) Usingultrasound with pulse lengths of 10/.•sand pulse repetition frequencies of 100 Hz, thethresholds for intestinal hemorrhage in miceafter a 5-minexposure range from - I MPaat I MHz to -4 MPaat 4 MHz. Witha piezoelectriclithotripter, the threshold forintestinal hemorrhage after 200 pulses was 1-3 MPa.In neithercase can the effects be explained by heating. As a testfor cavitation, theextent of hemorrhagein the gas-containing intestines of pregnantmice was compared to theamount of hemorrhagein the gas-free intestinesof theirfetuses. On the 18thday of gestation,the abdominal regions of pregnantmice (n = 6) wereexposed to 200 pulses
2485 J. Acoust.Soc. Am., Vol.99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2485
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 piezoelectriciithotripter. Acoustic pulses had a peakpressure amplitude of 10MPa and were administered at a rateof • 1 Hz. All mammalintestines showed hemorrhagic regions extending several centimeters in length.In contrast.only 1 of 43 exposedfetuses showedan intestinalhemorrhage and this one lesion was less than one millimeterin diameter.These are consistentwith a cavitation- relatedmechanism for the productionof intestinalhemorrhage by exposureto acousticfields.
2pPAaS.Effects of ultrasoundon function of the amphibian and the mammalian heart. Diane Dalecki, Alan MacRobbie, SallyZ. Child,Carol H. Raeman,and Edwin L. Carstensen(Rochester Ctr. for BiomedicalLIltrasound, Univ. of Rochester,Rochester, NY 14627)
Exposureto the frog heartto single,millisecond length pulses of ultrasoundhas been shown to causeeffects by two qualitatively differentphysical mechanisms. One of theseeffects has also been observed in mice.When the pulseis deliveredduring systole, it can ßcause a reductionin the developedaortic pressure. Evidence suggests that this arisesfrom an actionof radiationforce on the heart tissues.The effectcan be producedwith an acousticreflector over the heart.This maximizesthe radiationforce delivered to the heart, but eliminatesdirect interactionof the ultrasoundwith the hearttissue, thus experimentally eliminated heating and cavitationas mechanismsof action.When the pulseis deliveredduring diastole, it can producea prematureventricular contraction. No premature ventricular contractions were observed with the acoustic reflector over the heart. The mechanism is nonthermal. Available evidence doesnot precludecavitation as the primaryphysical mechanism responsible for prematureventricular contractions.
2pPAa6. Contrast agentsenhance biologicaleffects /n vivo. Diane Dalecki, Sally Z. Child, Carol H. Raeman,Charles W. Francis,David P. Penney,and EdwinL. Carstensen(Rochester Ctr. for BiomedicalUltrasound, Univ. of Rochester,Rochester, NY 14627)
Hemolysisin vivowas demonstrated by exposingthe heartsof miceto focused,pulsed uhmsound (l-MHz carrier,10-/xs pulses, 100-Hz repetitionfrequency, 5-min total exposuretime) while administeringa contrastagent via tail vein. The thresholdwas approximately4 MPa. This studysuggests that inertial cavitationcan take place in vivo if appropriatenuclei are present.However, sincethe degreeof hemolysisin the absenceof exogenousnuclei is indistinguishablefrom shamexposed blood with contrastagents, we mustconclude that the numberof spontaneousnuclei in normalblood in vivo is very small.The administrationof contrastagents duringlithotripsy enhanced hemorrhage in mostof the tissuesof the body.Thresholds for hemorrhagein the fieldsof a piezoelectric lithotripterwere <2 MPa.
2pPAa7.Acoustic eavitation and bioeffects in thevascular system. J.B. Fowlkes,E. A. Gardner,a)and P. L. Carson(Univ. of MichiganMedical Ctr., Ann Arbor,MI 48109-0553)
An in vivo bolusgeneration system has providedinformation concerning acoustic cavitation in blood and associatedbioeffects. Microbubbleboluses produced in the canineabdominal aorta by tonebursts of 1.8 MI-lz focusedultrasound were detectedin distal arteries using medical ultrasoundscanners and a resonantbubble detector.At the maximum acousticintensity, 19,000 W/em2(lsvT^),125-250 ms bursts generated contrast enhancement persisting several cardiac cycles. Intensities down to 3,700W/ cmzyielded progressively weaker boluses while shorter and weaker boluses were produced with 64-0.5 msbursts at themaximum acousticintensity. There was a 50% occurrenceof vascularwall effects(by histology)but no immediatemechanical failure. Oxygen ventilationhas been shown to destabilizeIV injectedcontrast agents and similarly, cavitation thresholds were elevated in the venacava. Resonantbubble dectection indicated the presenceof 7/xm diameterbubbles but the bubblesize rangeis unknown.These results provideinsight into bubbleproduction by acousticcavitation but any bioeffectsmust be examinedin the contextof arterial bolus productionwhere the risk of significantdamage may be lessthan that of alternativeprocedures. [Work supported in partby USPHS 5 RO1DK42290.] a•Current address: Acuson, Inc., Sunnyvale, CA.
2pPAa8.Finite volume model of weakshock interaction with lungtissue. S.M. Gracewskiand Zhong Ding (Mech.Eng. Dept. and RochesterCtr. for BiomedicalUltrasound, Univ. of Rochester,Rochester, NY 14627)
The lungand other organs with highgas content tend to be the mostsusceptible to damageby lithotriptershock waves. Since the gas volume is large, the damageprocesses most likely differ from traditionalcavitation mechanisms. A finite volume model has previouslybeen developed to investigatethe interactionof shockwaves with single,isolated bubbles. This modelhas been modified to exploreother possible mechanisms of lungtissue damage. In themodel, the singlebubble is replacedwith a layerof cylindrical bubbles,and a shockwave is incidentnormal to thisbubble layer. The affect of bubblespacing on the shock wave propagation through the layer and the resulting bubble dynamics is determined.
2pPAa9.Bioeffects in rat lungsfrom diagnostic ultrasound. Christy Holland (Univ. of Cincinnati,College of Medicine,Dept. of Radiology,P.O. Box 67042, Cincinnati, OH 45267)and Robert Apfel (YaleUniv., New Haven,CT 06520-8286)
2486 J.Acoust. Soc. Am., Vol. 99, No. 4, Pt.2, April1996 131stMeeting: Acoustical Society of America 2486
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 TUESDAYAFTERNOON, 14 MAY 1996 CANYON HALL, 1:15TO 5:00 P.M.
Session2pPAb
PhysicalAcoustics: Porous Media and Wave Propagation
James P. Chambers, Chair NationalCenter for PhysicalAcoustics. University of Mississippi.Coliseum Drive, University,Mississippi 38677
ContributedPapers
1:15 model.First, the classicalBiot-Allard equationsare rewrittenin termsof the solidphase macroscopic displacement vector and the fluid phasemac- 2pPAbl. Effect of anisotrnpy on elastic wave propagation in roscopicpressure. The newcoupled equations have the advantage of writ- fluid-saturated porous media. Andrei D. Degtyar, Stanislav L ing the poroclasticityequations in the form of the couplingbetween an Rokhlin,and Laszlo Adler (Dept. of Industrial,Welding and Systems equivalentelastodynamic equation for the solid phaseand an equivalent Eng.,Ohio StateUniv., 190W. 19thAve.. Columbus, OH 43210) Helmholtzequation for the fluid phase.In particular,the equivalentfluid On a mesoscalethe pore structure in naturalrocks may have preferred modelis transparentin the developedequations. Next, the associatedvaria- orienlation(texture} which leads to anisolropyof permeability,tortuosity, tinhalformulalion is presentedtogether with its numericalimplementation. andshape factor. !t is shownthat such an anisotropicfluid saturated porous Also the acoustic-poroelastic,elastic-poroelastie, and poroelastic- mediumsupport_• four diff':rentwave types:fast and slow quasilongitudi- poroelasticcoupling conditions are derived. Several examplesare pre- nal and two quasishearwaves. These results indicate that the velocitiesof sentedto showthe accuracyand effectivenessof the proposedmodel and the fastquasilongitudinal and two quasishearwaves mostly depend on the its couplingwith elastic and acousticmedia. In particulara systematic propertiesof the frameand are not sensitiveto the permeabilityand tor- comparisonis madewith the (u,U) finiteelement formulation. [Work sup- tunstrydirectly (the frame stiffnesses, permeability, and tortuosity are in- portedby Canadair,CRSNG, and FCAR.] directly relateddue to dependenceon pore structure,however formally theycan be consideredas independentparameters). Thus by measuring these velocities one could determine frame elastic constants. The slow wavevelocity, on the contrary,mostly depends on the poregeometry. Its angulardependence in a water-or air-saturatedsolid allows us to recover 2:00 the componenlsof the permeabilityand tortuosity tensors. This approach opensnew challengesin delerminationof suchcharacteristics of porous 2pPAb4. Application of Biot's poroelasticity theor)' for nonlinear materialsas preferred pore orientation and tortuosity which had been pre- acoustics. Dimitri M. Donskoy (Davidson Lab., Stevens Inst. of viouslyinaccessible experimentally. Technol., Castle Point on Hudson, Hoboken, NJ 07030), Khaldoun Khashanah, and Thomas G. McKee, Jr. (Stevens Inst. of Technol., Hoboken,NJ 07030) 1:30 The nonlineardynamic equations introduced by Blot to model po- 2pPAb2.Acoustic properties of porous model media of spherical roclasticmedia have not been implementedto describenonlinear acouslic particles. H. Tavossiand B. R. Tittmann (Dept. of Eng. Sci. and waves in such media.The equationsof the semilinearBlot model are Mechanics,Penn State Univ., UniversityPark, PA 16802) revisedand a mathematicalmodel depictingthe physicalnonlinearity is The throughtransmission method of longitudinalultrasonic pulses was established.A perturbationtechnique is thenapplied to findsolutions to the usedto investigatethe collectiveacoustic properties of a porousmedia nonlinearBlot equations.The compulationalresults are carriedout in de- modelof cohesionlessspherical particles. The resultsof this investigation tails for a one-dimensional model in which the contributions of the fast and showeddispersion and filteringeffects {Br the transmittedacoustic waves. slow compressionalwaves into secondharmonic wave are analyzed.The At low frequenciesthe wave velocitydecreased with increasein frequency correlation between second and third-order Blot coefficients and measur- and particlesize. In contrastat high frequenciesthe wave velocity de- able nonlinearparameters is alsopresented along with a parameteranaly- creased with increa•,ein particle size, for relatively large particles sis. (kR>• I ). Calculatedresults from existing theoreticalmodels for porous mediaby M. A. Biot, were comparedto the experimenlalresults. It was foundthat new modificationsof theexisting theoretical model for porous mediawere necessaryin orderto interprelthe dala in a quantitativeman- her. 2:15
2pPAb5. An action of seismicp-wave on fluid level in capillary. ] :45 VyacbeslavS. Averbachand Yury M. Zaslavsky (Inst. of AppliedPhys., RussianAcad. Sci., 46 Ulyanovstr., Nizhny Novgorod, 603600, Russia) 2pPAb3. A mixed displacement-pressureformulation for Biot's poroelasticequations. NoureddineAtalla, RaymondPanneton, Patricia It is a desolvedproblem about fluid level in capillaryin homogeneous Debergue (GAUS, Mech. Eng., Univ. de Sherbrooke,PQ J1K 2Rl, elasticmedium on which the seismicp-wave acts.This wave propagates Canada), and J.-F. Allard (Laura, Univ. du Maine, Le Mans, France) perpendicularto axis of a capillary.In a linear approachthe meniscus Recently,a displacement(u,U) finite element model for the three- vibrates with frequency to and amplitude as the same one as a classic dimensionalporoelaslicity problem has beendeveloped by Pennetonand oscillator.In the next approximationthere is the doublefrequency oscil- Atalla [J. AcousLSoc. Am. 98. 2976(A) 0995)]. This model,while accu- lation and a direct shift of the meniscus. Thus the fluid level will differ rate. hasthe disadvantageof requiringcumbersome calculations for large from the staticone. After averagingthe describedsolution on the orienta- finite elementmodels and spectralanalyses. To overcomethis difficulty, tionsand sizesof capillariesthe fluid level is estimatedin partly saturated this paperpresents a mixed displacement-pressure(u,P) finite element porousmedium.
2487 J. Acoust.Soc. Am., Vol. 99, No. 4, PI. 2, April 1996 131st Meeting:Acoustical Society of America 2487
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 2:30 3:30
2pPAb6. Dispersionrelation influenceon rise times of sonic boom 2pPAb9. Reduction of microphone wind noise using local wind propagationthrough turbulence. Allan D. Pierce (BostonUniv., Dept. velocitymeasurements. Michael R. Shusœand James C. Rogers (Elec. of Aerosp.and Mech. Eng., 110Cummington St., Boston,MA 02215) Eng. Dept., Michigan Technol.Univ., 1400 TownsendDr., Houghton.MI 49931) Recent work suggeststhe "average" turbulencecontribution to rise timesis accountedfor by an extraterm in thepropagation equation, evolv- A systemfor quietingmicrophone wind noise using local wind velocity ing from an extra term in the dispersionrelation k = (to/c)+ F(to), where measurementsis desirable.The conceptis shownto be feasible,however, c is spatiallyaveraged, and, for mechanicalturbulence, F(oJ) dependson optimizationof the cancellationsystem requires understanding the corre- turbulentenergy dissipation rate • per unit fluid mass.Previous analysis lationcharacteristics between microphone signals (pressure) and anemom- suggeststhat F(to) is -7.48 C•cei'a•c-?ata•a. Theextra term's in- eter signals(velocity). Wind datawas rex:order using microphones and fluenceis exploredwith a pulsebeginning with a stepfunctionin pressure anemometerswith separationdistances from 2.5 to 20 centimeters.The whichenters a turbulentatmosphere. After propagationthrough a distance measurementswere made in a singleplane parallel to the airflow.Both the x, therise time becomes of order of e2c 7x3.This cubic growth is even- microphonepressure and wind velocitysignals displayed an approximate tuallycurbed by thenonlinear stecpening effect; the above prediction is an l/f frequencycharacteristic. In addition,correlation strength between wind upperlimit to the turbulencecontribution. The discrepancywith the 1971 signals(both pressure and velocity) decreased with increasingseparation predictionthat the rise time scales as •4nc-•m.•l•t7is discussed,such distance.Correlation estimates from microphoneto microphone,anemom- beingconsistent with an to TM term in thedispersion relation. [Work sup- eter to anemometer,and microphoneto anemometerare presented.It is portedby NASA-LRC.] demonstratedthat adaptivesignal processing algorithms can be utilized to reducemicrophone wind noiseusing anemometer signals as a reference.
2:45
3:45 2pPAb7. Distorted-wave Born approximation analysis of sound levels in a refractive shadow zone. Kenneth E. Gilbert, Xiao Di, and 2pPAb10. Effects of wind velocity fluctuations on the statistical RodneyR. Korte (Appl.Res. Lab. andthe GraduateProgram in Acoust., moments of plane and spherical sound waves in the turbulent PennState Univ., P.O. Box 30, StateCollege, PA 16804) atmospherewith the Gaussian correlation function of wind velocity Measurementsmade by Havelocket al. showthat above a few hundred fluctuations.V.E. Ostasbev,G. Goedecke(Dept. of Phys.,New Mexico Hertz, the soundlevels in a refractiveshadow zone are weakly dependent State Univ., Las Cruces,NM 88003-8001),and JohnM. Noble (U.S. on frequency.Parabolic equation calculations made recentlyby Di and Army Res.Lab., White SandsMissile Range, NM 88002) Gilbert indicatethat the weak frequencydependence is consistentwith It is quite often assumedin the theoriesof wavesin randommedia that scatteringfrom small-sealeturbulence governed by a Kolmogorovspec- mediuminbomogeneities have a Gaussiancorrelation function. Equations trum. In this papera theoreticalanalysis is presentedusing the distorted- for themain statistical moments of planeand spherical sound waves propa- waveBorn approximation (DWBA) to showwhy the Kolmogorovspec- gatingin a mediumwith temperaturefluctuations are well known in the trumleads to the observedweak frequencydependence. Using DWBA, the literature.Among thesestatistical moments are the following:the mean problemof scatteringby turbulenceis formulatedin termsof a sampling soundfield, the variancesand correlation functions of log-amplitudeand functionthat showsthe physicalorigin of the frequencydependence by phasefluctuations, and the transverse coherence function. The presentpa- showingwhat part of the turbulencespectrum contributes in a typical per dealswith a derivationof equationsfor thesestatistical moments for measurement of levels in a refractive shadow. Results from the DWBA the caseof planeand sphericalwave propagationin the atmospherewith analysisare comparedwith the dataof Havelocket al. and with parabolic windvelocity fluctuations. It is shownthat the derived equations can differ 'equationcalculations. [Work supportedby theArmy ResearchLaboratory not only quantitativelybut alsoqualitatively from analogousequations for andthe AppliedResearch Laboratory.] the caseof soundpropagation in the atmospherewith temperaturefluctua- tionseven if the wind velocityand temperature fluctuations make the same contributions to the variance of the acoustical refractive-index fluctuations.
3:00-3:15 Break The resultsobtained are generalized to thecase of soundpropagation in an arbitrarymedium (for example,for soundpropagation in the oceanwith curtentfluctuations). [This material is basedupon Work supported by the U.S. Army ResearchOffice under Contract No. DAAH04-95-1-0593.]
3:15
2pPAb8. Measurementsof wind turbulence spectra near ground and
implications for sound propagation calculation. Michael R. Stinson, 4:00 Gilles A. Daigle, and David I. Havelock (Inst. for Microstructural Sciences,Natl. Res. Council, Ottawa, ON KIA 0R6, Canada) 2pPAbll. Acousticscattering from vegetation. Mark W. Sprague (Phys.Dept., EastCarolina Univ., Greenville,NC 27858) and JamesM. Measurementsof horizontalwind speedvariations have beenmade at Sabafier (NationalCtr. for PhysicalAeoust., University, MS 38677) a local airfield usingthree different techniquesand the resultingpower spectracompared. The instrumentsused were a rotating three-cupan- Acousticscattering from vegetationis a complicatedproblem that de- emometer, a sonic anemometer, and a hot-wire anemometer. The instru- pendson a numberof plantcharacteristics including biomass distribution, ment samplingrates and frequencyresponses lead to upperfrequency plantspacing, plant height, leaf sizeand shape, and the acoustic impedance limitsfor the spectraof 0.5, 10, and at least100 Hz, respectively.Good of theplant material. A theoryfor acousticscattering from vegetation could agreementwas obtainedbetween the techniquesfor those frequencies be the basis for a noninvasive acoustic measurement of some of these wherethey overlap.Knowledge of the shapeof the turbulencespectrum is characteristics,particularly biomass distribution. Two possibletechniques necessaryfor the incorporationof turbulencescattering into outdoorsound to characterizescattering from vegetationare the multiplescattering ap- propagationcalculations. The observedspectra tend to vary with frequency proachand the porousmedium approach. In the multiplescattering ap- f asf-so overthe range 0.001 to 100Hz (correspondingto turbulence proach,the vegetationis treatedas a slab of scattererswith a random lengthscales between 5000 and0.05 m, for a meanwind speed of 5 m/s) distribution.In the porousmedium approach, the vegetation is t•eatedas a althoughthere are significant deviations from this simple dependence. The porousmaterial with a veryhigh porosity. In thistalk, both approaches are observedresults are consistent with the analysis of Hfijstrup[J. Atmos. Sci. examined,and their predictions are compared for formsof vegetationsuch 39, 2239-2248 (1982)]. as wheat,corn, cotton, and soybeans.
2488 J.Acoust. Soc. Am., Vol. 99, No. 4, Pt.2, April1996 131stMeeting: Acoustical Society of America 2488
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 4:15 wave-like behaviorare found: both steady-stateand transientacoustic wavesand a dispersivewave due to the diffusivenature of the magnetic 2pPAb12. Comparison of sound-speed computation methods. field. Formulasare presentedfor the amplitudeand phaseof each type of GeorgeS. K. Wong (Inst. for Natl. MeasurementStandards, National Res. Council, Ottawa, ON KIA 0R6, Canada) wave. The usefulnessof thesefindings for describingacoustic effects in inductionsystems is discussed. The computationof soundspeeds in nitrogen,oxygen, and methane wasperformed with two methods.Results from the traditionalmethod that relied on virial coefficients B and their temperature derivatives T dB/dT,T 2 d2B/dT2, werecompared with those given by a simplified method.At a pressureof 101.325kPa, and at a temperatureof - 10 øC, the 4:45 maximumsound speed deviations between the two methodsare within 0.2cAand 0.4c• for nitrogenand oxygen,respectively. For methane,at 2pPAb14. Laser thermo-opticalsource of soundat a fractal surface the abovepressure, and over the temperaturerange from zero to 450 øC, in a liquid. Leonid M. Lyamshev (N. N. AndreevAcoust. Inst., the maximumdeviation is 1.2cA.For the above gases,the sound-speed deviationsbetween the methodsare largestat low temperatures.It can be ShvernikStr. 4, 117036Moscow, Russia) and M. L. Lyamshev (Russian shownthat by modifyingthe numericalvalues of the virial coefficientsand Acad. of Sciences, 117242 Moscow, Russia) their temperaturederivatives, the sound-speeddeviations between the two methodscan be reducedsubstantially. For nitrogen,when B, T dB/dT, Surfacesof real bodiesam rough,uneven, or porousas a role and are andT 2 d2B/dT2 aremodified by multiplication factors of -0.1, 0.55,and characterizedby fractal properties.Surfaces may be fractal up to the 0.7, respectively,the differencebetween the soundspeeds obtained with molecular-levelscale. Rough oceanic surface is alsofractal. Laser photo- the two methodsdecreases to lessthan •'-0.05•. It is notedthat the sign acousticdiagnostics of various media have been developing in recent of the numerical value of B is reversed. Uncertainties of the results ob- tained with both methods were examined. years.It is basedon laserexcitation of sound(ultrasound or hypersound). Specialfeatures of laser soundexcitation in a liquid half-spacewith the rough statisticalfractal surface are investigated.It is assumedthat an 4:30 harmonicallymodulated laser beam is incident on the liquid surface.The 2pPAb13. Analysis of electromagnetically induced pressure waves height(amplitude) of surfacewaves is greaterthan the soundwavelength internal to a rigidly confined, electrically conducting layer. John C. and the absorptionlength of light in the liquid. Fractal propertiesof the Petrykowski(Dept. of Mech.and Aerospace Eng., Univ. of Dayton,300 surfaceare characterizedby the Weierstrassfunction and connectedwith it CollegePark, Dayton,OH 45469-0210) by a structuralfunction. The Kirchhoff approximationis usedto solvethe A model is presentedthat relateshow electromagneticallyinduced boundaryproblem. The influenceof fractalproperties of the surfaceand pressurewaves propagate and grow in responseto a steady-stateelectro- parametersof laserradiation and liquid on the amplitudeand spatial char- magneticexcitation. A normalmodes-type solution is usedto help account acteristicsof intensityof the acousticfield excitedin a liquid by laser for noncompliantsurfaces that boundthe layer. In total, three types of radiationis analyzed.
TUESDAY AFTERNOON, 14 MAY 1996 REGENCY B, 1:00 TO 4:45 P.M.
Session2pPP
Psychologicaland PhysiologicalAcoustics: Pitch and Loudness
RobertP. Carlyon,Chair MRC Applied PsychologyUnit, 15 ChaucerStreet, Cambridge CB2 2EF, England
ContributedPapers
1:00 encepitch, was confirmeda secondexperiment, where listeners adjusted the F0s of two pulsetrains with differentP's to haveequal pitches. 2pPPl. The effect of mean rate cues on the pitch of filtered pulse trains. RobertP. Carlyon (MRC Apph Psych.Unit, 15 ChaucerRd., CambridgeCB2 2EF, England) 1:15 2pPP2. Potentialpitch cue for spectral-shapediscrimination at high Listenersjudged which of two bandpassfiltered (3900-5400 Hz) pulse frequencies. HuanpingDai (Boys Town Natl. Res. Hospital,555 N. trainshad the higher pitch. In the controlcondition, where the two trains 30th St., Otnaha, NE 68131) differedonly in repetitionrate, two cuesmight producea pitch difference. The interval betweenany two pulsesis a multiple of a commonperiod, In theseexperitnents on spectral-shapediscrimination [D. M. Green, which is shorter for the train with the faster rate (the "FO cue"). This ProfileAnalysis (Oxford U.P., New York, 1988)],the listener'stask was to stimulusalso contains more pulses(the "mean rate cue"/. Generally,tem- discriminatea standardspectrum in which all componentswere equal in poralpitch models focus on the F0 cue.The meanrate cue was investi- level, from a signal-plus-standardspectrum in which the level of one gatedby, in one condition,deleting a proportion(I-P) of the pulsesin component(the signalcotnponent) was higher than the level of other eachtrain, and manipulatingP so that the mean rate (?./• 0) was equal in components.The thresholdwas measuredas a functionof centerfrequency the two halvesof each trial [R. A. Dobie and N. Dilllet, Hear. Res. 18, (250 to 16 000 Hz) for cotnplexeshaving two or three components.The 41-45 (1985)]. Listenersidentified the stimulushaving the higher(origi- frequencycomponents were spacedequally on either a logarithmic nal) F0 as possessingthe higher pitch less reliably than in the control (J'i. •/fi = 1.38) or linear(A f= 150Hz) scale.For all the three-component condition,and lessreliably than in a conditionwhere the meanrate dif- complexes,in whichthe signalwas addedto the centercomponent, dis- ferencewas exaggerated. The conclusionthat the meanrate cuecan inllu- criminationwas difficult for frequenciesabove 2 kHz. For the two-
2489 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April1996 131st Meeting:Acoustical Society of America 2489
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 componentcomplexes, discrimination was difficult for the logarithmicbut "comparison"distributions (means of 401, 403, 406, and414 Hz for the not for the linear spacing.In the latter case,a changein spectralshape 400-Hz standard;566.5, 569.5, 572, and 584 Hz for the 565-Hz standard; causeda changein the centerof gravityof the stimuluspower spectra, and1002, 1005, 1010, and 1020 Hz for the 1000-Hzstandard). All samples whichwas perceived by listenersas a changein pitch.The availabilityof were 100-ms sinusolds. All conditions were alike to an ideal observer in the pitch cue madethe discriminationpossible for the narrowbandtwo- that the distributionswere normalwith a standarddeviation equal to the tonecomplexes at frequenciesup to 8 kHz. [Worksupported by NIH.] differencebetween the means.The resultsindicate that integrationof fre- quencyinformation appears constant across different frequencies when initial performanceis equated.[Work supportedby AFOSR through WPAFB AL/CFBA.] 2pPP3. Pitch strength discrimination for iterated rippled noise. William A. Yost (ParmlyHearing Inst., LoyolaUniv. Chicago,6525 N. SheridanRd., Chicago,IL 60626)
Thepitch strength of iteratedrippled noise (IRN) wasinvestigated in a 2:15 pitchstrength discrimination experiment. IRN is generatedby a cascadeof an add,delay (d in ms), andattentuate (g) circuit,where n representsthe 2pPP6. On the relations among temporal integration for loudness, numberof iteratedstages in the cLrcuit.In thisstudy g wasnegative, which loudness discrimination, and the form of the loudness function. representsthe cases in whichthe noise is subtractedrather than added. IRN Stren Buus (Communicationand Digital Signal Processing Ctr., Dept. of producesa pitch, which when n is negativeis either ambiguouswith a Elec. and Cornput. Eng., 409 DA, Northeastern Univ., Boston, MA pitch near 10% of the reciprocalof the delay,d, or at one over twice the 02115-5096),Mary Florentine (NortheastemUniv., Boston, MA 02115), delay,d. The strengthof the pitchvaries with g,n, andthe typeof circuit. and Totben Poulsen (Tech. Univ. of Denmark, DK 2800 Lyngby, Listenerswere askedto discriminatebetween two IRN stimulieach gen- Denmark) eratedwith the samed, but with differentvalues of g, and n, and different typesof circuits.The discrimination results could only be accountedfor by Temporalintegration for loudnesswas measured as a functionof level usingthe first peakin the autocorrelationfunction of thesestimuli. The from 2 to 60 dB SL using2-, 10-, 50-, and 250-mstones at 5 kHz. The resultswill be discussedin termsof recentcomputational models of pitch adaptive21,2AFC procedure converged at the level requiredto makethe processing.[Work supported by NIDCDand AFOSR.] variablestimulus just louderthan the fixed stimulus.Thus the datayield estimatesof the levelsrequired to maketones of differentdurations equally 1:45 loud and of the just noticeabledifferences for loudnesslevel. Resultsfor four listenerswith normalhearing show that the amountof temporalinte- 2pPP4. A neural computational model for tracking of multiple gration,defined as the level differencebetween equally loud short and long frequency-modulatedtones. Kiyoaki Aikawa and Hideki Kawahara tones,varies markedlywith level and is largestat moderatelevels. The (ATR HumanInformation Processing Res. Labs.,2-2 Hikaridai.Seikacho, effect of level increases as the duration of the short stimulus decreases and Sorakugun,Kyoto 619-02, Japan) is largestfor comparisonsbetween the 2- and250-ms tones. The loudness- This paperproposes a novelneural computational model for tracking level jnds are also largest at moderatelevels and, contraryto traditional frequency-modulated(FM) tones.The modelcan explain various interest- jnds for the level of two equal-durationtones, they do not appearto depend ing phenomenarelated to the perceptionof complexFM tones.The dy- on duration.The leveldependence of temporalintegration and the loudness namicprocess in perceivingthe pitchof FM tonescan be representedby jnds are consistentwith a loudnessfunction flog(loudness) versus SPL] two second-ordersystems having fast and slow responses[K. Aikawa thatis flatterat moderatelevels than at low andhigh levels. [Work sup- et al., J. Acoust.Soc. Am. 98, 2926 (1995)].An auto-regressiveneural portedby NIH-NIDCD R01DC02241 and the TechnicalUniversity of matrix model is newly proposedto simultaneouslytrack multiple FlVl Denmark.] tones.The model is characterizedby a novel neuralnetwork architecture called the counter-tonotopicconnection and a new tracking algorithm basedon the Lp-norm.Each FM tone is trackedwith second-orderre- sponsecharacteristics. Several interesting phenomena in perceivingcom- plex FM toneshave beenreported. For a stimulustone composedof 2:30 crossedupward and downwardsweep tones, two separatepitch streams 2pPP7. Dependenceof loudnessadaptation on frequencyand level. •vere not perceivedbut a bouncedpitch streamwas. When both of the Rhone P. Hellman (AuditoryPercept. Lab., NortheasternUniv., 360 crossedsweeps were downwardsweeps, two pitch streamswere merged HuntingtonAve., Boston,MA 02115), AndrzejMiskiewicz (Chopin andthen another new stream was perceived after the crossing point [Mat- Acacl. of Music, Warsaw,Poland), and Bertram Scharf (Nortbeastem sui,ASJ meeting,1995-09]. When a sweeptone was followedby white Univ., Boston,MA 02115) noise,the sweep was perceived as being extended into the noise [Masuda, ASJ meeting,1995-09]. The proposedneural tracking model successfully replicatedthese perceived images. The relationbetween simple loudnessadaptation and exposuretime was determinedfor continuouspure tones at eight frequenciesfrom 0.125 to 16 ld-lz and five sensationlevels (SL} from 5 to 40 riB. Adaptationwas 2:00 measuredover a 6-min exposureperiod in eightyoung listeners with nor- mal hearingby the methodof successivemagnitude estimation. Listeners 2pPP5. Information integration of signal frequency. Robert D. Irwin judged loudnessevery 20 s by assigninga number that matchedthe loud- and Daniel L. Weber (Dept. of Psych.,Wright StateUniv., Dayton,OH nessof the tone.At all frequencies,loudness declined over time, more so 45435) at low sensationlevels than at higherones, and more so at frequencies A listener'sability to integrateinformation can be evaluatedby pre- above8 kHz thanat lowerfrequencies, especially at 5- and 10-dBSL and sentingmultiple samplesin the distributiondiscrimination procedure. To at 16 kHz. Most of the adaptationoccurred within the first 3 min of examinefrequency discrimination with a 2IFC form of this procedure, exposure,slowly approachingasymptote around 6 min. Additionalmea- each interval containssamples drawn from one of two distributionsof surementsat 60 dB SL at threefrequencies showed that loudnessdeclined signal frequency.The listener indicateswhich interval containedthe after6 rain by 16% at 2 kHz andby as muchas 26% at 12 kHz. Results sample(s)drawn from the distributionwith the highermean. This experi- obtainedby loudnessmatching closely agreed with thosefrom magnitude ment evaluatedthe integrationof frequencyinformation in termsof im- estimation.Quantitative analyses revealed a clearrelation between pub- provement in frequency discrimination for an increasing number of lishedexcitation pauems based on maskingpaRems fla. /•wtclcerand H. samples(n= 1,2,3,4,5,6,8,12,16).Seven listenersdiscriminated a "stan- Fasti,Psychoacoustics (1990)] and the current adaptation data. [Work sup- dard" distribution(means of 400, 565, and 1000 Hz) from each of four portedby NIH.]
2490 J. Acoust.Soc. Am., Vol. 99, No.4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2490
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 the magnitudeestimated ipsilateral procedure appear to be mathematically relatedin a simpleway to adaptationexpected from the binauralSDLB 2pPP8. Deriving the Weber fraction from loudness functions. procedure.Pertinence of an interpretationbased on powers of 2 will be William S. Hellman (Dept. of Phys.,Boston Univ., 590 Commonwealth discussed. Ave., Boston,MA 02215) and Rhone P. Hellman (NortheasternUniv., Boston, MA 02115) 3:45 In a previouspaper [W. S. Hellmanand R. P. Hellman,$. Acoust.Soc. Am. 91, 2380(A) (1992)], Weberfractions for intensitydiscrimination 2pPPll, Ipsilateral comparison paradigm loudness adaptation: Is were derivedfrom their concomitantpure tone loudnessfunctions in nor- contrast hidden in complexity? Keith Jones,Ernest M. Weiler, Joel S. mal hearing.The calculationalprocedure employed a generalizedMcGill- Warm, William N. Dember, and David E. Sandman (Mail #379, Goldbergmodel. This work extendsthese findings to morefrequencies, to PsychoacousticsLabs, Univ. of Cincinnati,Cincinnati, OH 45221) broadbandnoise, to tones maskedby high-passnoise, and to forward Dangeet al. [J. Gen. Psychol.120, 217-244 (1993)] investigated masking.Weber functionsgenerated by the model are comparedto em- Weiler's ipsilateralcomparison paradigm (ICP) and determinedthat the pirical data for the variousexperimental conditions and stimuli. In all resultscould not be explainedas a functionof simple auditorycontrast. cases,the calculatedWeber functionscapture the overall shapeof the This studyintroduces a mixedreferent condition, wherein increasing and measuredintensity-jnd data over a wide stimulusrange. Not only doesthe decreasingreferents alternate in the sametrial. Resultsfrom all conditions modelproduce the near-missrelation for puretones in quiet,it alsopre- demonstratedthat bothbase and referenttones adapt under both levels of dictsWebefts law for broadbandnoise, a risingcharacteristic in theWeber intensity(50 and70 dB). If contrastwere the dominant influence, adapta- functionabove 60 dB SPL for a tonein high-passnoise, and the midlevel tion wouldnot be expectedin mixedor decreasingreferent conditions, nor humpobserved in forwardmasking. These results show that thereis suf- ficient information in the loudness function to recover the associated shouldthe referentsthemselves adapt. Thus contrast would not explain the results.However, certain preliminarypost hoc analysesmay reveal an intensity-jarlfunction. This implies that loudnessis the primary decision influencedue to contrast.Alternately, the simplereferent conditions show variablefor intensitydiscrimination. correspondencewith a modelfor binauraladaptation [Weiler and Hood, Audiology16, 499-506 (1977)].This analysis shows that the average for simplereferent ICP adaptationdiffers from binauraladaptation only by a 3:00-3:15 Break power of 2.
4:00 3:15 2pPPI2. Overview: Modeling ipsilateral loudnessadaptation as an 2pPP9. Reaction time adaptation: Hick's law may bias the outcome. indicator of peripheral function. Ernest M. Weiler, Jon Temple, T. Goldman, E. M. Weiler, D. E. Sandman,and J. M. Davis (ML #379, David E. Sandman,Ted Huber (ML #379, PsychoacousticsLab, Univ. of Communication Sciences and Disorders, Univ. of Cincinnati, Cincinnati, Cincinnati, Cincinnati, OH 45221), and Maureen Korman (Good OH 45221) SamaritanHospital, Cincinnati, OH 45221) Auditoryadaptation is characterizedby a decreasein apparentloudness Weilerand Hood [Audiology 16, 499-506 (1977)] andothers found overseveral minutes of time.This is truefor magnitudeestimated loudness thata highlyaccurate model could be constructedto accountfor adaptation adaptationmeasured either ipsilaterally [Weiler et el., Br. J. Audio.15, foundby the classicmethod of simultaneousdichotic loudness balances. 201-204 (1981)]or inducedbinaurally [Botte et el., J. Acoust.Soc. Am. However,when the ipsilateralcomparison paradigm (ICP) wasdevised to 72, 727-739 (1982)].The extent of ipsilateraladaptation is alsoa function avoidcomplications of binaural/interauraleffects, the SDLB modeldid not of timeof day[Sandman et el., J.Aud. Res. 22, 65-69 (1982)],as well as seemto fit [Weileret el., J. Gen.Psychol. 114, 411-421 (1987);errate, durationof exposure[Weiler and Cobb, J. Aud. Res. 22, 233-239 (1982)]. 1988]and others. Recently, studies by R. Tannenand K. Jones[unpub- The dB adaptationby the classicSimultaneous Dichotic Loudness Balance lishedMA thesesin progress,University of Cincinnati(1996)] seem to procedureprogresses over time [Hood,Acta Oto-Laryngol.$uppl. 92, haveprovided the basisfor a conversionfrom the SDLB modelto ICP 1-57 (1950)]. In 1976, Davis and Weiler [Br. J. Audio[ 10, 102-106] results.A criticalassumption is that binauralloudness effects are double found that simplereaction time (RT) to a constantintensity, increased that of ipsilateraladaptation. Work by the authorsand otherswill be re- reliablyafter 7 min of exposure,as if the intensityhad decreased. Goldman viewed with discussionof the strengthsand weaknessesof the model for et el. [J. Aud. Res.21, 13-16 (1981)] andWeiler et el. [J. Gert.Psychol. ipsilateraladaptation. 114 (1987; errata, 1988)] confirmedthis effect. However,in a modified design[T. Goldman,Ph.D. dissertation, University of Cincinnati(1985)] the reactiontime increasedsignificantly only for the secondtrial after 15 s 4:15 of exposure.Thereafter RT valuesdid not differ significantlyfrom the 2pPP13.A theory of the principal mortauralpathway. I. Pitch and baseline.Hick's law is offeredas an explanation,as well as differencesin time perception. Nell P. McAngusTodd (Dept. of Psych.,Univ. of procedurebetween RT adaptationstudies. Manchester,Manchester Ml3 9PL, UK)
A theoryof the principalmonaural pathway is describedaccording to whichtemporal information is spatiallycoded on threedimensions roughly 3:30 correspondingto the levelsof, respectively,the cochlea,the inferiorcol- liculus,and the auditory cortex [C. Schreinerand G. Langner,"Coding of 2pPP10. Binaural versusipsilateral loudnessadaptation: A simple relationship after all? Robert Tannen, Ernest M. Weiler, Joel S. temporalpatterns in the centralauditory nervous system," Auditor), Func- Warm, William N. Dember, and David Sandman (Mail #379, tion: NeurobiologicalBases of Hearing, editedby G. M. Edelmanet el. PsychoacousticsLabs., Univ. of Cincinnati,Cincinnati, OH 45221) (Wiley,New York, 1988), pp. 337-361]. This theory is expressedin the form of a computationalmodel which simulates peripheral and central Weilerand Hood [Audiology 16, 499-506 (1977)]reviewed a model processingand whichhas the followingmain components: (1) a one- of loudnessadaptation proposed by Hood.They foundthat the model dimensionallinear bandpass filter-bank to simulatethe cochlea; (2) a two- couldpredict adaptation measured by thetraditional simultaneous dichotic dimensionalamplitude-modulation (AM) bandpassfilter-bank to simulate loudnessbalance (SDLB) procedurewithin a few dB. However,failure to the colliculus;(3) a three-dimensionalAM bandpassfilter-bank to simulate correlatethis methodwith ipsilateralloudness adaptation forestailed at- layerIV receptivecells in thecortex; (4) a corticalcross-channel correla- temptsto convertthe modelto monaural/ipsilateraladaptation. The present tion mechanism;and (5) a centralpattern recognition mechanism. Overall, paperreports success at findinga meansof convertingthe Hood/Weiler periodicitypitch (i.e., periodsof up to about1000 Hz) is primarilyasso- modelto resultsfrom the ipsilateralcomparison paradigm. Results from ciatedwith subcorticalprocessing whereas time and rhythm (i.e., periods
2491 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society of America 2491
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 up to about20 Hz) are primarilyassociated with corticalprocessing. the thalamusand from neighboringeolunms. For columnswith coherent The modelis appliedto the followingphenomena: virtual pitch shift, thaiernieinputs, the outputsof the pyramidssum across frequency beeanse musicalchords, the psychophysical law for intervaldiscrimination, and the local intemeuronscompute a correlationbetween the AM transformof the filled imerval illusion. inputsof the localand remotecolumns, and selectivelygate the inputto the pyramidalcell. (l) Groupingby frequencyproximity--for columns sepa- 4:30 ratedby lessthan a criticalband, thalamic inputs are unresolved.(2) Groupingby temporalproximity--at repetitionrates below the meanof the 2pPP14, A theory of the principal monaural pathway. IL Rhythm, streaming, and comodulationmasking release. Neil P. McAngus AM distribution,AM fundamentalsare less well represented;at higher Todd (Dept.of Pscyh.,Univ. of Manchester,Manchester M13 9PL, L!K) repetitionrates the AM harmonicsare more separated.(3) Temporal development--wherethe AM spectratake time to develop.The AM co- The modeliN. Todd,"A theoryof the principalmonaural pathway. I. berencemechanism also gates the inputsto disjointsubpopulations of a Pitchand time pemeption," I. Acoust. Soc. Am. (theseproceedings)] pro- low-passmechanism, and thus also accountsfor comodulationmasking posesto accountfor auditorystreaming by a cross-correlationmechanism release,since backward masking will only takeplace within a singlesub- modeledas an arrayof corticalcolumns. A columncontains excilatory and inhibitoryintemeurons and pyramidal cells which receive input from both population.
TUESDAY AFTERNOON, 14 MAY 1996 REGENCY D, 1:00 TO 5:00 P.M.
Session2pSC
Speech Communication: Prosody
Ann R. Bradlow, Chair PsychologyDepartment, Indiana University,Bloomington, Indiana 47405
Contributed Papers
1:00 durationand amplitudeare a functionof bothstress and, to a lesserextent, level of the prosodicbonndary. Nasal duration was greater as stresslevel 2pSC1. Timing of fundamentalfrequency control in word accentof increased.However, nasal amplitude was greater in the onsetof unstressed the commonJapanese. Hiroya Fujisaki,Sumit Ohno, and TohruUeno syllables immediatelyfollowing stressedsyllables than in the onset of (Dept.of Appl. Electron.,Sci. Univ. of Tokyo) stressedsyllables. Regarding phrasal boundaries, word-initial nasalswere The accentualpatterns in Japanesecan be consistentlydescribed in longer than syllable-initialnasals, but only in unstressedenvironments, termsof rapidrises and falls in pitch,and their timing can be quantitatively supporting an interaction between stress and phrasing. Furthermore, specifiedby the onsetand offset of the underlyingaccent command applied utterance-initialnasals were longerthan syllable-initialnasals, but had less to a modelfor F 0 contourgeneration [H. Fujisakiand K. Hirose,J. Acoust. amplitude, suggestingstrengthening (increased "consonantality") in Soc.Jpn. (E) 5, 233-242 (1984)]. The presentpaper describes a quantita- utterance-initialposition. tive study on the timing of accentcommands relative to the acoustic- phoneticcharacteristics of the moraeand phonesin utterancesof the com- mon lapanese.The speechmaterial consists of wordsof varyinglength, phoneticconstituents, and accenttypes, embedded in a carrier sentence. The timing of the accentcommand was estimatedfrom the F o contourby 1:30 analysis-by-synthesis,while the timing of phonesand moraewas detected by referringto the frequency-time-intensitypatterns. It wasfonnd that the 2pSC3. A comparativestudy of focus realization in three Swedish relative timing of the accentcommand can be consistentlydescribed in dialects. RobertEklund (TeliaRes. All, SpokenLanguage Processing, reference to the onset of vowel rather than the onset of a more when the S-136 80 Haninge,Sweden) latterstarts with a consonant.Systematic variations in the timing due to phoneticconstituency and accenttype are formulatedas rules for speech State-of-the-artspeech recognition and speechtranslation systems do synthesis. not currentlymake useof prosodicinformation. Utterances often have one or moreconstituents semantically focused by prosodicmeans and detec- 1:15 tionof thefocus/loci of an utteranceis crucialfor a correctinterpretation of the speechsignal. Thus, a semanticmodel of focusshould be linked to 2pSC2. Nasal duration and amplitude as a function of stres• and a model describingthe acoustic-phoneticcorrelates of the speech.How- prosodic phrasing in Estonian. Matthew K. Gordon (Dept. of ever,variability exists at boththe semanticand the prosodicends. Seman- Linguist.,UCLA, 405 Hilgard Ave., Los Angeles,CA 90024) ticallydifferent kinds of loci mightbe associatedwith specificprosodic Cross-linguistically,segments are often lengthened and/or strengthened gestures.Also, a semanticallyspecific type of focusmight be realizedin at prosodicboundaries, where the degreeof lengthening/strengtheningis differentways in differentvarieties of a given languagesince general generallycorrelated with the level of the boundary:The larger the bound- intonationalpatterns vary betweendialects. In thispaper, focus realization ary, the longer/morestrengthened the segment.Stress often inducessimilar in threedifferent dialects of Swedishis investigated.Subjects from Stock- lengthening/strengthening.In this study,the durationof Estoniannasals holm, G&eborg,and Maim;5recorded three sets of four sentenceswhere wasmeasured in utterance-,word-, and syllable-initial position in theonset focuswas systematically put on fourdifferent constituents by havingthe of unstressedand stressed(primary and secondary)syllables. Nasal am- subjectsanswer wh-questioas. Since Swedish is a languagewith two tonal plituderelative to the immediatelyfollowing vowel was also measured in accents, words with these accents both in and out of focus were included. these contexts in order to draw inferences about the elfeel of stress and Dialectal as well as individual variation in focus realization is described prosodicboundaries on nasalarticulation. Preliminary results revealed that with emphasison invariantand optional phenomena.
2492 d. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2492
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 chlear implant using the PW first to find his appropriateF0 registerand then practicingpitch gesturesappropriate for speech.Strong carryover of 2pSC4. Pitch range and focus in Hindi. James D. Hamsberger learningto latersessions is demonstrated.[Work supported in partby an (Programin Linguist.,Univ. of Michigan,1076 Frieze Bldg., Ann Arbor, SBIR grantfrom N1H.] M148109)and Jasmeet Judge (Univ.of Michigan,Ann Arbor, M148109)
A studyof intonationin Hindi includedsentences, read by six native 2:30 speakers,in whichdifferent individual words were emphasized or focused. Hindiresembles some other languages (English, Bengali, Korean) in mark- 2pSC7. Perceiving the difference between spontaneousand read ing a focusedconstituent prosodically by reducingthe normal prominence speech:The role of physicalduration. RobertE. Remez,Jennifer S. givento neighboringconstituents. In Bengaliand English,all constituents Lipton,and Jennifer M. Fellowes (Dept.of Psych.,Barnard College, 3009 precedinga focusedword are deaccented,failing to showtypical contours Broadway,New York, NY 10027-6598) [Hayesand Lahiri, Nat. Lang. Ling. Theory 9, 47-96 (1991)].The reverse Despitethe greateraverage duration of spontaneoussentences relative occursin Korean,with followingconstituents being deaccented (Jun 1993, to matchedfluently read sentences,it is difficult to identify the physical dissertation).In Hindi, deaccentingof followingconstituents is also ob- basisfor determiningwhether an utteranceis spontaneousor read.The served;however, the phenomenon is characterizedby a dramaticcompres- pm,5.entexperiment compared judgments of spontaneitywith judgments of sion of the speaker'spitch range following the focusword. For narrow durationfor the samespeech samples. The test materialcomprised 25 pitchranges, compression effects on F0 realizationare equivalentto those sentencepairs in whichone sentencewas spokenspontaneously and one of deaccenting.For widerranges, following constituents show the typical sentencewas mad, both producedby the same speaker.On each trial, risingcontours over contentwords found in declarativeutterances without subjectsidentified the sentenceof the pair thatwas spokenspontaneously, focus,though at a narrowerrange than for the focusword. The theoretical and the sentencethat was longer in duration;tests were blockedby judg- significanceof Hindi focusis to illustratelanguage-specific differences in ment type. The greaterthe absoluteduration difference was betweenthe markingfocus while supportinga generalcross-linguistic strategy of re- two sentences,the bettersubjects performed on the durationjudgment. The ducinglocal prominences.These data also provide additional evidence for physicaldifferences in durationdid not predictthe spontaneityjudgment, the head-initial(Hindi, Korean)versus head-final distinction in prosodic nor did the durationjudgment correlate with the spontaneityjudgment. The phrases(Bengali, English). resultssuggest that physicalduration alone is not an effectiveattribute underlyingthe perceptualdifferentiation of spontaneousand read utter- 2:00 ances.[Work supported by NIDCD.]
2pSC5. Foreign-accentedrhythm and prosodyin reiterant speech. KeiichiTajima (Dept.of Linguist.,Cognit. Sci. Program, Indiana Univ., 2:45-3:00 Break Bloomington,IN 47405), JonathanDalby (Commun.Disord. Techno]., Inc., Bloomington,IN 47404), and Robert Port (Indiana Univ., 3:00 Bloomington,IN 47405) 2pSC8. Detectionof sentenceaccents in a speechrecognition system. The prosodiccharacteristics of utterancesproduced by second- Per Sautermeisterand Bertil Lyberg (Telia Res. AB, S-136 80 Haninge, languagelearners were investigated using reiterant speech (RS), a stylized Sweden) form of speakingin which every syllableis replacedwith a standard syllablesuch as [ma], so thatthe phrase"the table"is pronounced"ma Speechrecognition systems do not usuallyutilize prosodic informa- MAma."Native speakers of Chineseand Spanish produced RS versionsof tion, i.e., informationsignaled by segmentalduration and the fundamental shortphrases in Englishand in theirnative language. Preliminary phonetic frequencycontour of the speechsignal. The acousticmanifestation of analysisshows that the EnglishRS tokenswere less accurately produced prosodyis, moreoften than not, consideredas a disturbancein current thanwere the native-languagetokens. A subsetof the Englishtokens were statisticalapproaches to thespeech recognition problem. The detection and thenused as stimuliin a perceptiontest in whichnative English listeners transformationof sentenceaccent in, e.g., spokenlanguage translation heard each RS phraseand judged whetherit "matched"or "did not systems,will enablestress on a certainword in onelanguage to be trans- match" an Englishphrase presented to them visually.The stimulusset formedinto a suitablerepresentation of correspondingconstituents in the consistedof EnglishRS producedby bothnon-native and native speakers. otherlanguage and satisfythe samesemantic goal. In this study,a system Preliminaryresults indicate that listeners were better at judging the match/ for automaticdetection of sentenceaccents to be usedin speechrecogni- mismatchof thenative English RS tokensthan the non-nativetokens. This tionsystems, is presented.The fundamentalfrequency is extractedfrom resultindicates that there are perceptuallyrelevant differences between the speechsignal and an estimatedfrequency declination is subtracted nativeand foreign-accentedRS, and suggeststhat practice in producing from the actualfundamental frequency in orderto give a normalizedrep- moreauthentic English RS mightbe a usefulmethod of teachingaspects of resentationof the variations.These fundamental frequency variations are Englishprosody to second-languagelearners. [Research supported by givenin musicalintervals. The interpretationsof sentenceaccents are NIH-NIDCD GrantNo. 2R44DC02213-02.] carried out from this normalized manifestation of the fundamental fre- quency.Both the system architecture and some preliminary results will be shown. 2:15
2pSC6. Interactiveprosody training workstation. GeorgeD. Allen 3:15 (Collegeof Nursing,Michigan State Univ., E. Lansing,MI 48824)and V. PaulHarper (Harper& Assoc.,W. Lafayette,IN 47906) 2pSC9. Speech-rateeffects on the perception of second formant transitions. AlexanderL. Francisand Howard C. Nusbaum (Dept. of Few devicesexist to aid in the trainingof pitch, intensity,and rhythm Psych.,Univ. of Chicago,5848 S. Univ.Ave., Chicago, IL 60637) of speech.The Interactiveprosody training workstation (PW) employs state-of-the-arttechnology to assistusers in achievingclinicJan- or client- Researchon contexteffects in speech-ratenormalization generally fo- programmabletargets in eachof thesefeatures. Two training interfaces are cuseson theperception of phoneticcategories distinguished by temporally currentlyimplemented. The simplerdisplays F0 and/orintensity in real definedcues like VOT or F2 transitionduration. For example,a syllable time as a fluctuatingone- or two-dimensionaldisplay, Smoothing can be thatis heardas [ba] in thecontext of a slowlyspoken carrier sentence will adjustedto accommodatevarying levels of voicevariations. With the more likelybe identifiedas [wa] in a quicklyspoken context [Minifie et al., J. advancedinterface, model utterancesare presentedusing stored LPC- Acoust.Soc. Am. Suppl.I 62, S79(1977)]. This suggests that the category codedspeech. The user'sresponse is thencompared to the model,using boundarybetween [b] and[w], whenbased on an F2 transitionduration any of a wide varietyof scoringmethods. The user'sresponse may be cue, is interpretedrelative to the talker'scurrent speaking rate. One im- played,in comparisonto the model, as often as desired. A demonstration plicationof prior researchis that speakingrate changesonly affectthe tapewill be playedshowing one hearing impaired individual with a co- perceptionof durationalcues. However, research on phoneticcue trading
2493 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2493
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 suggeststhat temporaland spectralcues are perceivedtogether in an in- andhence louder vowel [Edwards et aL, J. Acoust.Soc. Am. 89, 369-382 tegratedfashion based on phoneticknowledge. Since changes in speaking (1991)].On theother hand, a studyof nonlowback vowels in alveolar rate may restructurespectral as well as temporalcues in production,lis- contextsshowed higher and backer tonguebody in accentedsyllables, tenersmay showsimilar context effects for perceptionof thesecues. This suggestinga more peripheralvowel [de Jong,J. Acoust.Soc. Am. 97, studyexamines the effect of changingspeaking rate contexton the per- 491-504 (1995)].This paper reexamines the two hypotheses by lookingat ceptionof [b] and[w] stimulidistinguished by variationin transitiondu- both jaw and tongue for both phonemicallylow and high vowels. Five rationand extent of frequencychange. Implications for theoriesof speech- speakersof AustralianEnglish read 20 tokensof two short discourses rate normalization are discussed. whichplaced the name"Babber" or "Beaber"twice each in accentedand deaccentedpositions. Jaw and tonguepositions were recordedsimulta- 3:30 neouslyusing a magnetometer.On average,the jaw was lower in all ac- 2pSCI0. Vocal expression of emotion is associated with spectral centedsyllables, although the difference was smaller for thehigh vowel. At propertiesof speech. Jo-AnneBachorowski {Dept. of Psych.,Wilson the sametime, the tonguebody reachedsignificantly higher positions in Hall, Vanderbilt Univ., Nashville, TN 37240) and Michael J. Owren accentedhigh vowels, and somewhatlower positionsin accentedlow (ReedCollege, Portland, OR 97202) vowels.Thus the two hypothesescan be reconciledby their applicationto the two differera articulators. Most empiricalwork in vocal expressionof emotionhas emphasized proaodiccomponents of speechproduced by actors.In the presentstudy, spectralproperties of speechsamples that were producedduring naturally occurringemotional states were examined.Twenty subjectsviewed 24 slides selectedfrom the internationalAffective Picture System. Elicited emotionalresponses ranged from stronglynegative to stronglypositive. 4:15 During the presentationof eachslide, subjectsprovided a free-formde- 2pSC13. Jaw displacementand F0 in contrasfiveemphasis, Donna scriptionof the feelingsand thoughtsevoked by the picture,preceded by Erickson(Ctr. for Cognit.Sci., Ohio S•ate Univ., Columbus, OH 43210) thestock phrase "This testpicture .... "Subjectsconcluded each narrative and Kiyoshi Honda (ATR Human Information Proc. Res. Labs., with the prompt"Next testpicture." Analyses of the spectralproperties of Soraku-gun,Kyoto 619-02, Japanand Univ. of Wisconsin,Madison, WI individualphoneroes, drawn from the secondstock phrase, showed statis- 53705-2280) tically significantinteraction effects involving slide valenceand subject emotionalintensity. Representations in the frequencyspace formed by FI This studyexamines the relationshipbetween highest F0 (withinthe and F2, as well as tile spaceformed by F0 and F2, were relatedto both SOhorantportion of the syllable)and maximum jaw displacement(lowest currentemotional state and to the intensitywith which subjectstypically verticalposition of the mandiblein referenceto the maxillaryoeclusal experienceemotional responses.The obtainedeffects were of sufficient plane)in utteranceswith contrastireemphasis. Acoustic and articulatory magnitudeto be perceptible,and indicatethat an emotion experienced recordingswere madeusing the x-ray microbeamfacilities at the Univer- duringvowel productioncan affectthe sameacoustic cues widely heldto sity of Wisconsin[J. Westburyand O. Fujimura,J. Acoust.Soc. Am. be usedin a listener'sphonetalc processing. [Work supported by NIMH.] Suppl.I 85, S98 (1989)].Three American English subjects produced question-answersentences like "Is it 599 Pine Street?No, it's 59FIVE 3:45 PineStreet," reading from a monitordisplay with a markingon the digit to 2pSCll. An acoustic evaluation of variation in the overlap of be emphasizedeither in initial,middle, final position, or with no emphasis. consonant and vowel gestures induced by speaking rate change. The data showedpositive correlation between jaw openingand F0 for Kris Tjaden {Dept.of CommunicativeDisorders, San Diego StateUniv., syllablesspoken with contrastireemphasis, but no correlationfor nonem- 5500 CampanileDr., SanDiego, CA 92182) andGary Weismet {Univ. of phasizedsyllables. One would expecttwo oppositebiomechanical effects Wisconsin,Madison, WI 53705) ofjaw openingon F0: a positiveeffect by theaction of jaw openingmuscle on larynxelevation, and a negativeeffect by passivehyoid retraction due There is a growingbody of empiricaldata supporting a gestural-based to jaw lowering.These findings suggest that prosediecontrast may be view of speechproduction in whichadjacem speech gestures temporally achievedby reorganizationof interactive control of jaw openingand F0. andspattally overlap one another. Recent work suggeststhat certain acous- Possibleacoustical, physiological, and phonologieal ramifications of these tic measuresare sensitiveto changesin the overlapof adjacentconsonant findingsare discussed. [Work supported by NSFSBR-951199B and ATR/ andvowel gestures [G. Weismeteta/., J. Phon.23, II 1-126 (1995);E. ITL, Kyoto,Japan.] Zsiga,J. Phon.22, 121-140(1994)]. Utilizing a gradedspeaking rate task, eightspeakers produced 160 repetitionsof tentarget words embedded in a carrier phrase.F2 onsetfrequency, measured at the consonant-vowel 4:30 boundaryof test syllables,was used to index the degree of spectral- temporaloverlap of adjacentconsonant and vowel gestures.Regression 2pSC14. A kinematic analysisof contrasrivestress. Lisa Goffman analyseswere used to evaluatethe extent to which F2 onset predicted andAnne Smith (Dept.of Audiol.and SpeechSciences, Purdue Univ., temporal variability in F2 formant trajectoriesdue to speaking rate West Lafayette, [N 47907) change.Results suggest that consonant and vowel gesturesdo not simply temporallyslide away from eachother with slowedspeaking rate. Rather, The presentinvestigation examined the shapeand variationof move- modificationsin the formand magnitude of vowelgestures are requiredto ment patternsassociated with specificstress contexts. Movements of the accountfor the presentacoustic data. An empiricallybased acoustic model lowerlip wererecorded using the Optotrak, a noninvasivesystem in which of variationin gestureoverlap induced by speakingrate change is offered. light emittingdiodes are attachedto the movingstructure. Eight adult Individualspeaker differences also are discussed. subjectsproduced versions of the utterance"Buy Bobbya puppy"that varied in stress.Initally, this utterancewas producedwith normal stress 4:00 patterns.Then, a scenariowas presented that elicited a contrastirestressed 2pSC12. Competinghypotheses concerning the articulation of stress form (e.g., to stress"Bobby," the subjectresponded to the utterances in English. JonathanHarrington, Sallyanne Palethorpe (Speech Hearing "Don't buy Kathya puppy.Buy Bobbya puppy.").A standardtechnique and LanguageRes. Ctr., MacquarieUniv., SydneyNSW 2109, Australia), in the analysisof kinematicdata is to measureabsolute values of peak JanetFletcher (Univ. of Melbourne,Victoria, Australia), and Mary E. velocity,displacemere, and duration. Analyses revealed that, as expected, Beckman (Ohio StateUniv., Columbus,OH 43210-1298) increasedduration and amplitudeoccurred in stressedcontexts. A second setof analysisprocedures involved the evaluation of underlyingmovement Previousstudies have suggested two differenthypotheses concerning patternsthrough time and amplitude normalization (i.e., collapsingabso- the articulationof stresscontrasts in English.Examination of low vowels lutedifferences in durationand amplitude). Pattern recognition techniques surroundedby labialconsonants generally shows lower jaw in accentedas werethen applied, revealing that underlying patterning differed as a func- opposedto unaccentedsyllables, a resultoriginally interpreted as a lower tion of contrastirestress. [Work supported by NIDCD.]
2494 J. Acoust.Soc. Am., Vol. 99, No.4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2494
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 4:45 guishdeclarative and interrogativesentences, if thesetwo typesof sen- tenceshave similar intonational contour patterns? Following Lyons (1977) 2pSC15. Interrogativeword is the focus of questionin the WH andLi & Thompson(1979), question words are the focus of questionsin questionsentences in MandarinChinese? Yueh-chin Chang (Dept.of an interrogativesentence. They shouldhave a phonetic,acoustic realiza- ForeignLang., Natl. Tsing-huaUniv., Hsin-chu,Taiwan, ROC) tion more importantthan other words in the sentence.However, in the In nontonallanguages, intonation is a very importantprosodic feature primarystudy about the interrogativeword "ji" with third tone (how to distinguishsentence meanings. But in tonallanguages, such as Manda- many)in WH-questionsentence. "ji" had a shortduration, it had not rin Chinese,declarative and interrogative sentences both have falling in- undergonethe 3-tonetone sandhi. and wasrealized as a neutraltone. This tonation.In this case,interrogative sentences differ from the formerby studywill examinein detailthe acoustic phonetic realizations of interroga- havinga questionparticle in the finalposition of thesentence or a question tive words,to find out their prostritefeatures and to know how listeners word.At the prosodiclevel, what are the prostritefeatures which distin- react to these features.
TUESDAY AFTERNOON, 14 MAY 1996 CELEBRATION A, 1:00 TO 2:00 P.M.
Session2pSPa
Signal Processingin Acoustics:Shirtsleeve (Practical) Statistics
Edith L. R. Corliss, Chair ForestHill• Laboratory,2955 AlbemarleStreet, N.W., Washington,DC 20008-2135
Chair's Introduction--l:00
Invited Papers
1:05
2pSPal. The need for efficientmonitoring of data. Edith L. R. Corliss (ForestHills Lab., 2955 AlbemarleSt. NW, Washington, DC 20008)
"ShirtsleeveStatistics" is a namethat has been applied to simplifiedmethods for inspectingstatistical properties of experimental data. Many of thesetechniques are in the natureof "nonparametric"statistical operations. Because of their simplicity,they are particularlyvaluable for monitoringthe results of an experimentin progress.Also, study of the inherentrelations of the variablescan makefor a moreefficient layout of an experimentalprocedure. One vital resultof thisstudy of observationsand their uncertainties is the elucidationof the quantityN, the numberof independentvariables involved in an experiment.Merely countingthe numberof observationsdoes not suffice. Internal correlations can affect the degree of independenceof theobservations and thus exaggerate their estimatedprecision. Techniques are availablefor simpleand timely monitoringof measurementconsistencies. it is exceedingly importantto keep a runningstatistical surveillance of data. Inherentvariations in the phenomenabeing measuredmay obscure temporarilya failureia the measuringor datareduction equipment. Much time anddata can be lost.(Remember: Dust swept under the rugraises a lump.)
1:25
2pSPa2.A methodfor analyzing rating scaledata. Harry Levitt (Ctr. for Res. in Speechand HearingSciences, Graduate School andUniv. Ctr. of the City Univ. of New York, 33 W. 42ridSt., New York, NY 10036) Subjectiveratings are oftenused in the evaluationof hearingaids. loudspeakers, speech processors, and other systems involving sensorystimuli. The analysisof ratingdata, however,presents problems since the usualparametric assumptions underlying standard statisticaltechniques (e.g.. t tests.analysis of variance)are not applicable to subjectiveratings. A nonparametricmethod of analyzing ratingdata is describedusing concepts derived from signal detection theory. In orderto comparetwo setsof ratings,a nonparametric estimateof thearea under the ROC curveis obtainedby firstderiving the correlation function relating the two setsof ratingsand then summingover half the range of thecorrelation function. This statistic, the half summed correlation (HSC), is relatively easy to compute andcan be used to test,with known statistical power, for variousdifferences between two sets of ratings(mean differences, variance differences,mean plus variancedifferences). It is also possibleto rank setsof ratingsusing this statisticand to apply various multidimensionaltechniques designed for ordinaldata. A variationof the analysisof proximitiesusing HSC's will alsobe described. [Worksupported by NIDCD.]
2495 J. Acoust. Soc. Am., Vol. 99, No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society of America 2495
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
and detectweak signalsburied in noise.These processors take advantage of the notionthat signals from submergedsources (especially those which 2pSPa3.Sirnulations for performanceevaluations of a family of undergorelatively fewer interactions with the surface) are relatively steady fluctuation-basedprocessors. Jacob George (Naval Res. Lab., Code thoughthey may be weak, but ambientnoise has greaterfluctuations. 7176,Stennis Space Center, MS 39529) Simulationsusing synthetic data havebeen done to verdy the validityof the abovepremises, and to assessthe performance of the familyof filters A familyof processorsdeveloped at NRL [R. A. Wagstaff,"The collectivelycalled "WISPR" underseveral environments. The simulations WlSPR Filter:A methodfor exploitingfluctuations to achieveimproved are alsocompared with analysesof experimentaldata. The resultsof the sonarsignal processor performance," (submitted to I. Acoust.Soc. Am.)] simulationsand the experimental analyses will be discussed.[Work sup- havebeen shown in dataanalyses to yieldgains in signal-to-noiseratios, portedby ONR.]
TUESDAY AFTERNOON, 14 MAY 1996 CELEBRATION A, 2:10 TO 5:00 P.M.
Session2pSPb
SignalProcessing in Acoustics:Signal Characterization and Time-SpaceAnalysis
P. G. Vaidya,Chair Mechanicaland MathematicalEngineering Department, Washington State University, Pullman, Washington 99164
Chair's Introduction--2:10
Contributed Papers
2:15 basedon the FFT algorithm,is robustand fast. It will be shownthat transformyields accurate estimates of onsetand offset times for periodic 2pSPbl. Analysis of induced chaos in Duffing's equation, using andaperiodic signals as well asfor vowelcenters and the ramp frequencies Caseygrams.P. G. Vaidyaand C. R. Winkel (Schoolof Mech. and of formant transitions. MaterialEng., Washington Stale Univ., Pullman, WA 99164)
In speechsignals, a newertype of chaoshas been observed. It couldbe 2:45 termedas an "inducedchaos." In orderto seeif this type of chaoscan be stimulated,in a theoreticalsetting, the Duffing'sequation has been looked 2pSPb3. Acquisition of FM waveform parameters from vibration of at. The parametersof this equationhave beenchosen in sucha way that rotational machine elements using FM wavelet template matching. thiswould result in an outputwhich is normallynonchaotic. However, the MichaelB. Van Dyke, DavidC. Swanson,and Karl M. Reichard (Appl. driving amplitudehas been modulated,and in turn, the phaseand the Res.Lab., PennStale Univ., P.O. Box 30, StateCollege, PA 16801) drivingfrequency. All of theseled to "inducedchaos." This chaosdiffers in certainimportant characteristics from the usualchaos. It wasfound that Vibrationsignals obtained from rotatingmachinery exhibit frequency the best way to detectsuch a chaoswas to use the differentialtrans- modulatedcomponents resulting from torquevariations due to wear and spectrograms,or the "Caseygrams."These are obtainedby calculatingthe irregularitiesin theelements. The characteristicshape of theFM signaland differencebetween two specific types of trans-spectralcoherences, (TSC's) degreeof modulationcan be useful metricsfor the determinationof the [P. G. Vaidyaand M. J. Anderson,I. Acoust.Soc. Am. 89, 2370-2378 nature and extent of element degradation.A nonorthogonalFlvl wavelet (1991)].These two TSC'sare specifically developed to measurethe inter- templatematching technique is usedto quantifythese parameters. Results action of the main harmonics with the subharmonics. These results show are comparedwith FM waveformsobtained by signaldemodulation, dem- that as the modulations increased the induced' chaos became more and onstratingfairly good accuracy. moreapparent in termsof the differencebetween the TSC's, and thusin the Caseygram.A theoreticalexplanation of theseresults is included. 3:00
2pSPb4. Computer imaging features for classifyingsemivowels in 2:30 speechspectrograms. Ben Pinkowski and Jack Finnegan-Green (Dept. of Cornput.Sci., WesternMichigan Umv., Kalamazoo,Nil 49008) 2pSPb2.Acoustic signal analysisusing Gabor-type windows. Izidor C. Gertnet,Stephan Lueci, and John Antrobus (Depts.of Cornput.Sci. Speechspectrograrns can be analyzedusing computer image process- andPsych., City Collegeof New York,New York,NY 10031) ing techniquesto yield highrecognition rates lB. Pinkowski,Pattern Rec- ognition26, 1593-1602 (1993)].In particular,Fourier descriptors (FD's) Transientsin speechand other acousticsignals are usually irregular have provenuseful for characterizingthe boundaryof segmentedisolated and very difficult to analyzebecause of their short and nondeterministic wordscontaining the Englishsemivowels (/w/, ly/, /l/, It0. This study duration.Therefore the traditionalFourier analysis technique does not give examinesthe appropriatenessof FD's combinedwith 17 other general satisfyingresults. The classicalGabor techniqueuses a Gaussianwave- featuresfor classifyingspectrogram images. The other features include form window.However, it is not numericallystable and it has slow con- eigenvaluesand eigenvectors,gray-level variance and covariance,ran- vergence.In order to do time-frequencyanalysis of acousticsignals, a lengthand chainencodings, and segmentsize, shape,and compactness. window transformis proposedthat is derivedfrom a Gaussianusing the Principalcomponents (PC's) are usedfor featurereduction on a speaker- Zak transform.The resultingwindow possesses good locality properties in dependentdata set consistingof 80 soundsrepresenting 20 speaker- boththe time and frequency domains. The computational procedure, which dependentwords containing semivowels. With eightcombined features,
2496 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, Apdl1996 131stMeeting: Acoustical Society of America 2496
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 includingfour 32-point FD's and four general features obtained from prin- modeto be isolatedfrom the multicomponentwave fields,and the subse- cipalcomponent analysis, a 97.5%recognition rate was obtained using a quentdetailed analysis of its slownessand attenuation.Furthermore, the lineardiscriminant function. This rate washigher than that observed for extractedspectral information can be usedto reconstructthe space-time anygroup of featuresconsidered separately, [Work supported by NIH.] descriptionfor theindividual mode, thereby providing the complete dual- ity of viewingthe individualcomponents in both the space-timeand frequency-wave-numberdomains. This procedurewill be demonstrated 3:15 usingboth model[C. J. Randall,J. Acoust.Soc. Am. 90, 1620-1631 2pSPbS. Use of multiresolution analysis to calculate pitch in (1991)]and field datasets. presenceof noise. SalvadorCerdfi (Lab. de Acdst.,Dept. de F•sica Aplicada,Facultad de CirnciasFisicas, c/o Doctor Mollnet, Burjasot 46100,Spain) and J. Romero (Lab.de Acdst.,Burjasot 46100, Spain)
The aim of thiswork wasto determinethe effectof noisepresence at 4:00 lime to evaluatethe pitch.and the studyof possibleimprovements. Several algorithms(Terhardt, Duifhuis, Cepstmm, simple FFT, and visualdeter- 2pSPbS. Wideband higher-order spatial processingof active sonar mination)were studied. These algorithms were applied to differentSpanish echoes. Roger F. Dwyer (InformationProcessing Branch, Naval vowelswith a progressivelyincreased noise level; conclusionsabout the UnderseaWarfare Ctr., New London,CT 06320) precisionof eachmethod are presented. In general,the noise causes a loss of accuracybecause time-domain data are blurredand spuriouscompo- When linearsonar arrays are operatedwell beyondtheir design fre- nentsappear in the spectrum.At this pointthe multiresolutionanalysis quency.spatial resolution is reducedat low frequenciesand grating lobes (MRA) techniquebecomes a usefultool to eliminatethe effect of elevated appearat higherfrequencies based on the second-orderspectrum. Because noiselevel. MRA was usedto smooththe vowelsanalyzed and then the the higher-orderspectrum provides more flexibilityin choosingthe fre- algorithmsunder study were appliedanother time. With this procedurean quencyresponse at the outputof a beamformer,the deliteriouseffects of wide bandwidths can be reduced. This will be demonstrated with active accuracyimprovement in all methodsthat work in the frequencydomain was observed. sonarwaveforms returned from sphericaltargets.
3:30
2pSPb6. Vowel identification from harmonic contours of vowel 4:15 centers using an automatic algorithm that eliminates windowing error. OctavioBelancourt and John Antrobus (Depts.of Cornput.Sci. 2pSPb9. Model referencesignal processingfor a laser ultrasonics and Psych.,City Collegeof the City Univ. of New York, New York, NY experiment. James V. Candy. Graham H. Thomas. Diane Chinn 10031) (Lawrence Livermore Natl. Lab., Univ. of California, P.O. Box 808, L-495, Livermore, CA 94550), and JamesB. Spicer (JohnsHopkins Univ., Usingsuccessive nonoverlapping 22.5-ms windows, 16-kHz sampling, Baltimore,MD 21218) no filtering, an automaticalgorithm locates five successivewindows of minimumspectral velocity, describes a subwindowequal to somemultiple Laserultrasonics is an excitingoptical methodology of nondestructive of the naturalperiod of F o, and mapsthe subwindowonto the unit circle, evaluationoffering a meansof detectingflaws in materialsespecially in the interval0, 2•'. Consequently,the Fourieranalysis is performedon a hostileareas where contact transducers cannot function such as high tem- windowwhere the signalis exactlyperiodic. Because the spectrumcon- peratureenvironments or awkwardareas where the laseris easilydirected tainsno extraneousnumerical sidebands it is precise,and consists only of by mirrorsfor rapid scanningand measurement.Typical measurement naturalharmonies in the acousticsignal. The first32-imeger multiples of techniquesutilize laserinterferometers to accuratelymeasure surface dis- F 0 aresufficient to describethe spectrum. J. D. Miller's[J. Acoust.Soc. placements.In thispaper the feasibility of applyingmodel-reference signal Am.85, 2114-2134(1989)] IogF• a shiftincreases recognition of 12 processinglechniques are investigatedthat would improvethe perfor- vowels(men, women, and children) in the Hillenbrandet al. [J. Acoust. manceof a moderatecost, Michelson interferometrie measurement system. Soc.Am. 97, 3099-3111 (1995)] data set from 52% to 75% usinga A model-referenceapproach is developedto solvethe signalenhancement Euclideanclassifier (EC withjackknife). Cosine series (12) wereused to problemfor a laserultrasorties application in nondestructiveevaluation. In compareour Betancourtspectrum (EC: 76%) with the Hammingwindow this problema sophisticatedlaser thermoelastic propagation model is used (EC: 61%). Quadraticdiscriminant function analysis + log Fo (79%) adds to predictthe surfacedisplacement of the specimenunder test. Once syn- only3% to our best EC result. With this spectrum and a logF• a shift,most thesized,this modeldisplacement response is usedas the referencesignal vowel informationis clearlycaptured by a simpleEC. in an optimal(minimum error variance) signal enhancement scheme. Both fixed and adaptiveprocessors are consideredin this applicationwhere it is 3:45 shownthat a significantimprovement in signallevels can be achievedover the usualmethods to enhancenoisy data acquired from a Michelsoninter- 2pSPb7.Extraction and analysisof individual wavefieldcomponents ferometricmeasurement system and increaseits overallsensitivity. from boreholespace-time arrays. M.P. Ekstrom (SchlumbergerAustin Res.,8311 North RR620, Austin, TX 78720)and C. J. Randall (SciComp, Inc., 5806 Mesa Dr., Ste. 250, Austin. TX 78731)
Spectralanalysis approaches have been shownto be usefulfor the 4:30 purposeof analyzingdispersion characteristics from boreholeacoustical measuremeals[M. E Ekstromand C. J. Randall,J. Acoust.Soc. Am. 98, 2pSPb10. Acoustic-optichybrid imaging experiment. Anthony D. 2867 (1995)].In thisapproach, the receiverwave fields are processed Matthewsand Lisa L. Arrieta (CoastalSystems Station, Dahlgren Div., usinga hybrid spectralestimator, with the space-timearray first being Naval SurfaceWarfare Ctr., PanamaCity, FL 32407-7001) transformedinto the space-frequencydomain, and a high-resolutionesti- mator basedon the matrix pencil usedto estimatethe wave numbersat A seriesof experimentsto determinethe ability of laservibrometers to each frequencyof interest.In the frequency-wave-numberdomain, the receiveand process echoes from the watersurface are described.Imaging spectralestimates are of sufficientquality to allowthe decompositionof of the bottomand objectslying on the bottomis attempted.The excitation the spectraldescription into its constitutiveparts, The frequency-wave- is accomplishedby a submergedacoustic source operating near 10 kHz. numberplane is segmentedto capturethe loci of polesfor an individual The degradationof the image is quantifiedas a functionof wave height. modeor headwave,and the spectralcomponents within this segmentex- Experimentresults are reported. [Work supported by CoastalSystems Sta- tractedfrom the spectraldescriptor matrices. This allows an individual tion underInternal Research funding.]
2497 d. Acoust. Soc. Am., Vol. 99, No. 4, Pt. 2, April 1996 131st Meeting: AcousticalSociety of America 2497
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 4:45 requiresa referenceand holds the arrayduring the measurementof pres- sures.Instead, the proposedmethod measures the hologramcontinuously 2pSPb11. Planar acoustic holographic reconstructionhy using a by a moving array withouta reference.Its basicidea is that the pressure movingarray. H.-S. Kwon, S.-H. Park,¾.-H. Kim (NO¾IC. Dept.of signalof a movingmicrophone is modulatedwith the carrierfrequency Mech.Eng., KAIST, Taejon305-701, Korea), and B.-S. Ko (Duewoo whichis the frequencyof the soundfield. Although this is a time signal,it Motor Co., Inchon, Korea) includesthe spatialinformation of pressuredistribution; i.e., hologram, Planaracoustic holography has been well acknowledgedas a useful due to a constantmoving speed. The bandwidthof modulatedsignal is toolto predictwhole sound fields in space.In practicalapplications, how- directlyproportional to the Mach number,therefore generally narrow, a ever,an insufficientnumber of microphoneshas trouble measuring whole bologramcan be successfullyrecovered unless there is a closelylocated holograms,therefore limiting the improvement to constructa better picture frequency;not closerthan the bandwidth.Also thistechnique can be di- of sound.This problem conveys the issue to virtuallyincrease the number rectlyapplied to the hologrammeasurement of a movingsource with a of microphonesso thatit canconstruct a better,realistic sound field. As fixed array.This methodis demonstratedby computersimulations and one of thesemeasuring techniques, the conventionalmanning technique experiments.
TUESDAY AFTERNOON, 14 MAY 1996 CELEBRATION B, 1:15 TO 4:50 P.M.
Session2pUW
Underwater Acoustics:Scattering
John R. Preston, Chair AppliedResearch Laboratory, Pennsylvania State University,P.O. Box 30, StateCollege, Pennsylvania 16804
Chair's Introduction--l:15
ContributedPapers
1:20 amplesare presentedto illustrateenvironmental effects on the backscatter by a bubbleand an elasticspheroid that penetratea water/sedimentinter- 2pUWl. Forward scatteringat 400 Hz from rough seas in the face.[Work supported by ONR.] presenceof a range-independentunderwater bubble layer. Guy V. Norton,Richard S. Keiffer (Naval Res.Lab.-SSC, Stennis Space Center, MS 39529),and Jorge C. Novatint (PlanningSystems, Inc., LongBeach, 1:50 MS 39560) 2pUW3. Scattering front a fluid loaded elastic spherical shell in Of fundamentalinterest to the underwateracoustics coramunity is the proximity to a rough interface: Numerical results. Judy Smith and role that bubblesmay play in connectionwith scatteringfrom the rough Garner C. Bishop (Naval Undersea Warfare Ctr. Div., Newport, RI air/sea interface.In this paper a high fidelity waveguidepropagation and 02840) seasurface scattering model known as FEPE-CM[G. V. Nortonet al., J. Acoust.Soc. Am. 97, 2173-2180 (1995)] is appliedto the problemof A null field T-matrix formalismis developedand used to calculate forwardscattering from a roughair/sea interface in the presenceof a depth- plane-wavescattering from a fluid loadedelastic spherical shell in prox- dependent(horizontally statified) bubble layer. The numericalexperiments imity to soundhard, soundsoft, fluid-fluid, and fluid-elastic interfaces consideredwere designed to explorethe role of upwardrefraction (due to with periodic surface roughness.For each type of interface, the the presenceof the bubbles)on forwardscattering from the air/seainter- Helmholtz-Kirchhoffintegral representation of the variousscattered pres- face.Results from these numerical experiments will be presented.Prelimi- sureand displacement fields are constructed; the surface fields are required nary resultsshow an enhancementto the forwardsurface scattered field. to satisfythe appropriateboundary conditions and the scatteredfields are [Worksupported by ONR.] requiredto satisfythe extendedboundary condition. Spherical basis func- tions are used to construct a free field T-matrix for the elastic shell and rectangularvector basis functions are usedto constructa representationof the free field T-matrixfor the roughinterface. The free field T-matricesare 1:35 introducedinto the Helraholtz-Kirchboffequations for the scatteredfields 2pUW2. Acousticscattering by a partially buried three-dimensional andthe null field equationsfor the shell-interfacesystem and an "exact" elasticobject. RaymondLim (CoastalSystems Station, Code 130B, analyticalsolution is obtained.Numerical results are obtainedthat dem- PanamaCity, FL 32407) onstratethe effecta of boundarytype, elastic parameters, roughness SCOrn- eta, amplitude,and slope on the scatteredpressure field andon the ability A formallyexact transition-matrix solution for the spectralscattering to "see" the scatter from the elastic shell. responseof an elasticobject that penetratesa plane-stratifiedfluid hostis formulated.The field scatteredfrom the segmentin each layer is expanded in a global outgoingbasis centeredon that segmentand these segment 2:05 fields are superimposedat the field point. A manageablestructure for the 2pUW4. Computing the acoustic field scattered from proud, transitionmatrix is maintainedby usingthe boundaryconditions to couple partially buried, or totally buried cylindrical objects. John A. thesesegment fields to the interior field of the objectvia a singleexterior Fawcett (SACLANT UnderseaRes. Ctr., 19138La Spezia,Italy) surfacefield expansioncentered on the origin of the object. The standard setof regularspherical eigenfunctions of the Helmholtzequation are used A boundaryintegral equation method which utilizes the Green's func- to expandthe exteriorsurface field. Numericaltests for an axisymmetric tionfor a 2-half-spaceacoustic medium and the Fourier-Bessel represen- spheroidindicate this choiceyields a viable solutionbut convergenceis tationof the acousticfield withina cylindricalobject is presented.This betterfor flattenedshapes (oblate) than elongated shapes (prolate). Ex- formulationallows for the accuratecomputation of the acousticfield scat-
2498 d. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2498
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 temdfrom a cylindricalobject (possibly, with interiorlayering) which can and correlationsare soughtbetween true grazingangle and backscattered be above,below, or intersectthe waveguideinterface. The waveguide signal strength.Beamformed and match filtered acousticdata from the Green'sfunction and its radialderivative are expressed in termsof wave- monostatic,wideband, LFM experimentat Site A are used to find the numberintegrals. The asymptotic(large wave-number) behavior of these scatteringstrength corresponding to specificareas of the seafloor.Scatter- integralsis thenevaluated in termsof Henkelfunctions and asymptotic ing strengthdetermined from intersectingbeams of differentsegments are reflection and transmission coefficients. The numerical treatment of these summedto reduceleft-right ambiguity.At the scaleof analysis,high termsmust be consideredcarefully; in particular,for the caseof the par- scatteringstrengths are foundto correspondto steepflanks of seafloor tially buriedcylinder. Spectral backscattering curves are computedfor featuresand can be usedto maptheir shape and orientation. Some of these cylinders with varying degrees of burial. Also, the results of two- featuresare characteristicof specificcrustal regions. Scattering strength is dimensionalfull field computationsare shown. foundto increasewith increasingeffective grazing angle at a rateof about 0. I +-0.01 dB/degree.However dip valuesare so scatteredthat the seafloor 2:20 dip, on Ihe scaleof a few hundredmeters cannot be usedto predictback- scatterintensity. Some other characteristics of steeplydipping areas, such 2pUW5. Measurement and localization of interface wave reflections as subsurfacebeterogeneities or smallerscale surface features, strongly from buried objects. Eric Smith, PrestonS. Wilson, Fred W. Bacon, influencethe level of backscatteredsignals. [Work supported by ONR.] JasonE Manning,John A. Behrens,and ThomasG. Muir (Appl. Res. Labs.. Univ. of Texas,Austin, TX 78713-8029) 3:05-3:20 Break It is demonstratedthat inletfacewave reflectionsfrom buriedobjects can be created with an active seismic interface wave sonar, and measured andlocalized on a seismicarray. The sonarreported here was implemented 3:20 on a naturalbeach of the Gulf of Mexico. It employsa monostaticsource/ 2pUW8. Vertical spatial and temporal coherenceof ocean bottom receiver geometrywith a three-elementhorizontal receiving array, in reverberation. DajunTang, George V. Frisk,Cynthia J. Sellers (Woods which each element is a triaxial geephone(velocimeter}. Detailed mea- Hole Oceanograph.Inst., WoodsHole, MA 02543), and Dan Li (MITI surementsof propagationloss at the site make it possibleto compare WHOI Joint Programin Oceanogr./Oceanograph.Eng., WoodsHole, MA reflectedsignal power with the resultsof predictionscomputed in first 02543) order,pointlike-scatterer perturbation theory. These propagation measure- ments,together with phaseinformation, verify that the reflectionsare in- An experimentto studyacoustic backscattering from deep-oceansedi- terfacewaves. and measuredvalues agree well with predictions,within mentswas conductedin July 1993 as part of the AcousticReverberation experimentaland theoretical errors, both of whichare well constrainedand SpecialResearch Program (ARSRP). An acousticsource transmitting chirp small.Simulated data are usedto comparea beampattern at uniform signalsin the frequencyrange 250-650 Hz and a 24-elementvertical shadingwith experimentalresults, and it is foundthat nonuniformshading receivingarray attachedto the sourcewere suspendednear the seafloor in the experimentaldata producesclosest correspondence. Independently over a sedimentpond in the vicinityof the Mid-AtlanticRidge. In a performedground truthins and reverberationanalysis further providea previouspaper [Tang et el., J. Acoust.Sec. Am. 98 508-516 (1995)],a consistentand thorough picture of the backgroundsound fields from which studyon bottomscattering due to sedimentvolume inhomogeneities in this theseechos must be extracted.[Work supportedby the Office of Naval area was presented.Here, the spatialand temporalcoherence of the scat- Research.] tered field usingthe data collectedon the vertical array will be examined. The scatterersare modeledas point scatterers.It is shownthat whenthe 2:35 coberentlyreflected signals due to sedimentlayering are removedfrom the measurements,the resultsof the point scatletcoherence model agree sat- 2pUW6. Backscatteringmechanisms for reverberation from deep isfactorilywith data.[Work supported by ONR.] oceanfeatures using ARSRP data taken at the Mid-Atlantic Ridge. J. R. Preston (Appl. Res. Lab., Penn StateUniv., R O. Box 30, State College,PA 16804) 3:35
In July 1993 SACLANTCEN participatedin an experimentfor the 2pUW9. A note on scattering by a stack of rough interfaces. Dajun acousticreverberation special research program (ARSRP). The primary Tang (WoodsHole Oceanograph.Inst., Woods Hole, MA 02543) objectivewas to take high-resolutionmeasurements to determinethe de- Scatteringby a stackof randomrough interfaces is studied.Such in- tailed physicalprocesses dominating the low-frequencyscattering from terfaccsare commonin both shallowwater and deepocean sediments due rough topographicfeatures and from deep sedimentpond areas.A very to the naturalsedimentation processes. When the roughnessof eachinter- detailedset of monostalicand bislatic scatteringexperiments were con- faceis small,first order perturbation theory of Bassand Fuks [Wave Scat- ducted(using low frequenciesfrom 200-375 Hz) just westof the Mid- teringfrom Statistically Rough Surfaces (Pergamon, New York,1979)] is Atlantic Ridge near 26ø N and 47ø W. This paperpresents towed array employedto formulatethe scatteredfield due to suchan interface.If the datarecorded by SACLANT Centre'sR/V ALLIANCEfor comparisonwith distancesbetween interfaces are small comparedto the acousticwave- FEPE two way parabolicequation model estimates of selectedARSRP lengthand the variationsof sedimentproperties are small,it is foundthat geometries.The receiverswere horizontal arrays of 128elements spaced at the collective scattered field due to a stack of random interfaces can be 0.5, I, and 2 m. Source/receiverdepths were •130 and 450 m, respec- relatedto that due to a weak scatteringvolume where sound speed and lively. Inferencesfor monostaticbottom scattering mechanisms are dis- densityare randomlyvarying. Thus low-frequency subbottom scattering cussedbased on the FEPE modelfrom Collins to interpretthe data.The due to either weak volume inhomogeneitiesor a stackof rough interfaces modelingwork isolatesdifferent scatteringmechanisms to assesstheir canbe formulatedin a unifiedfashion. [Work supported by ONR.] relative contributions to the overall reverberation levels observed in the data. 3:50 2:50 2pUWi0. Bottom backscattermeasurements at 100 and 200 kHz 2pUW7. Seaflooracoustic backscattering from different geological with high angular resolution. Anthony F. Parkinsonand Stuart D. provincesin the Atlantic Natural Laboratory. RobertJ. Greavesand Aristee (Maritime Operations Div., Defence Science and Technol. RalphA. Stephen(Woods Hole Oceanograph. Inst., 360 WoodsHole Rd., Organisation,Wharf 17, PtrramaRd., Pyrmont,NSW 2009, Australia) Woods Hole, MA 02543) Measurements of the variation of acoustic bottom backscatter with The characteristicsof acousticsignals backscattered from inside-corner incidentangle have beenmade at 100 and 200 kHz at sitesin Sydney oceaniccrust and outside-coruercrust are investigatedusing acoustic re- Harbour,Australia, with bottomtypes varying from sandwaves to mud. verberationdata from the 1993ARSRP Acoustics Cruise. Specifically, the The measurementswere madewith transducersmounted on a rotatingarm seafloordip distributionis comparedbetween areas of eachcrustal type with a radiusof approximately2.4 m. Angularresolution of approximately
2499 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society of America 2499
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 0.2ø was achievedover a rangeof nearly90 ø. Twin camerasattached to geometricconfigurations are considered,and the dependenceof bistatic the rotatingarm allow the recordingof stereoimages of the bottomin scatteringstrength upon the incidentand scattered grazing angles, as well favorablecases, giving a modelof the scatteringsurface allowing a com- asthe "bistafic," or azimuthalangle, is computedfor variousseabed types. parisonof measuredbackscatter with that numericallyestimated from sur- The parametersof the modelinclude mean values for bulk propertiesand face scatteringalone. parametersdefining the spectraof fluctuationsin bulk propertiesand sea- bed relief. The influenceof shearelasticity is examinedby comparison 4:05 with the caseof a fluid seabedhaving the samedensity and compressional wave speed.It is shownthat sheareffects on bothroughness and volume 2pUWll. Angular variation in the simulated reflection and componentsof scatteringare small for sandswhich consequentlycan be scattering properties of granular poroclastic ocean sediments. treatedas acousticfluids for realisticshear velocities (approximately 300 Dennis1. Yeltonand NicholasP. Chotiros (Appl. Res. Labs.,Univ. of m/s andless). For consolidatedsediments and rock, shear effects are domi- Texas,Austin, TX 78713-8029} nant,complicated, and very sensitiveto bottomparameters. Volume scat- teringexhibits a strongdependence on correlationsbetween the parameter Reflectionand scatteringproperties of an inhomogeneousporoelastic medium were studiedvia numericalsimulation. The inhomogeneousme- fluctuationsas well as their spectralaspect ratio. [Work supportedby dium was modeledas an ensembleaverage of randomlylayered poroelas- tic material. Each layer representeda granularmaterial of a particular grainsize.The thicknessof eachlayer was relatedto the associatedgrain- sizeand porosity by a conservationof massrelationship. Lateral variations in grainsizewere approximatedby performinga coherentensemble aver- 4:35 age of resultsfrom severalrealizations of the randomlystratified medium. Poroelasticmedium parameters were chosento representwater-saturated 2pUW13. Moderate-frequencyscattering from layered sediments sand.The mean and standarddeviation of the grainsizedistribution were over an elasticbasement. AnatoliyN. Irakin (AndreevAcoust. Inst., chosento matchexisting experimental data in order to test the model. Shvernika4, Moscow117036, Russia) Specifically,the inhomogeneousmedium was modeledas boundedby a homogeneouswater half-spaceon the sourceside, and a homogeneous In previouswork a high-frequencymodel for soundscattering by an poroelastichalf-space of equivalentaverage porosity on the other side. irregularelastic seabed with volume inhomogeneitiesand roughwater- Reflectedsignals were computed for high-frequencyplane waves incident seabedinterface was examined [A. N. Irakin andD. R. Jackson,J. Acoust. at variousgrazing angles.Coherent and randomcomponents of the re- Soc.Am. 98, 2989(A) (1995)].Scattering from fluid layeredsediments fleetedsignal were calculated.The coherentpart was relatedto the reflec- with differentkinds of irregularitieswas also consideredearlier [A. N. tion coefficient.The random componentwas related to the scattering Ivakin,J. Acoust.Soc. Am. 95, 2884(A) (1994)]. But, at manysites, the strengthof themedium. Results were compared with existingexperimental seabedis of a composite-typeconsisting of an irregularfluid sediment data.[Work supported by ONR.] layeror layerscovering an elasticbasement. In thiscase, a fluid scattering modelis adequateonly for sufficienthigh frequencies such that absorption 4:20 rendersthe influenceof theelastic basement negligible. At lowerfrequen- cies, soundpenetration of the sedimentincreases, and the effectsof scat- 2pUWI2. High-frequency bistatic scattering from elastic seafloors. teringfrom the basementas well as additionalchannels of scatteringfrom AnatoliyN. Irakin (AndreevAcoust. Inst., Shytroika 4, Moscow117036, Russia)and Darrell R. Jackson(Univ. of Washington,Seattle, WA 98105) withinthe sediment due to reflectionfrom the basement become important. Theseeffects are consideredand their sensitivityto differentmodel pa- A high-frequencymodel of bistaticsound scattering is consideredas- rametersis analyzed. Frequency-angulardependencies of scattering sumingan elastic seabedwith spatiallyfluctuating bulk parametersand a strengthare calculatedfor differenttypes of seabed,and possible applica- slightlyrough surface. The first-orderperturbation solution is usedto ob- tionsof predictedinterference patterns to remotesensing of the seabedare tainan approximateexpression for thebistatic scattering strength, different discussed.[Work supported by ONR.]
2500 d. Acoust.Soc. Am., Vol. 99, No.4, Pt.2, April1996 131stMeeting: Acoustical Society of America 2500
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, 15 MAY 1996 MT. RUSHMORE, 8:00 TO 11:50 A.M.
Session 3aAA
ArchitecturalAcoustics and Musical Acoustics:Directivity of Musical InstrumentsI
David J. Prince, Cochair The TalaskeGroup, Inc., 137 North Oak ParkAvenue, Oak Park, Illinois60301-1336
Richard H. Talaske, Cochair TheTalaske Group, Inc., 137North Oak Park Avenue, Oak Park, Illinois 60301-1336
Chair's Introduction--8:00
Invited Papers
8:10
3aAA1.Musical instrument directivity in differentplaying modes, environments, and amplifications.Daniel W. Martin (7349 CloughPike, Cincinnati,OH 45244)
Directionaleffects are reviewed for orchestraltrumpet and French horn, for piano,and for organpipes. The implications for each will be discussedrelative to differentacoustical environments and instrumentamplification systems.
8:30
3aAA2,Modes of vibrationand directivity of percussioninstruments. Thomas D. Rossing(Phys. Dept., Northern Illinois Univ., DeKalb, IL 60115)
Musicalinstruments in the percussion family radiate sound from many normal modes of vibration.These modes have distinctly differentradiation patterns, resulting in a soundfield that varies markedly with frequency and with time. Some of themodes of vibrationand the resulting radiation patterns obtained from a representativenumber of percussioninstruments, including bells, various typesof drums,and cymbals, are described.
8:50
3aAA3.Directivity of a simplifiedclarinet. WilliamJ. Strongand Scott D. Sommerfeldt(Dept. of Phys.& Astronomy,Brigham YoungUniv., Provo, UT 84602) A simplifiedclarinet was modeled as a closed-opentube of uniformcross section with an open tonehole lattice near its open end. Thetube had a lengthof 50 cmand a diameterof 1.5cm. The tonehole lattice consisted of five identical toneholes spaced at 2.8-cm intervals.Each tonehole was 0.8 cm in diameterand had an effectivelength of 1.3cm. The openend of the tubeand each of the toneholeswas treated as a simplesource, and a correspondingsource strength (volume velocity) was calculated at frequencies of interest.The far-field radiated pressure was calculated at a constantradius in a planethat included the tonehole lattice. The pressure wascalculated atangular positions from 0 deg(open end) to 180deg (closed end) for normal mode frequencies. (Circular symmetry aboutthe tube axis was assumed.) Significant directional patterns were seen for frequenciesabove 2000 H2. Experimentswere performedon a similarstructure to measurethe directivity and for comparison with the calculations.
9:10 3aAA4.Directional radiation by wind instruments, P.L. Hoekje(Dept. of Phys.,Univ. of N. Iowa,Cedar Falls, IA 50614-0150)
Aswith most musical instruments, the radiation patterns of windinstruments include directional components that can provide the listenerwith important timbrai cues in a room.The most significant radiation comes froln vibrations of the internal air column that are transmittedeither through the woodwind tone holes or the opening of thebrass instrument bell. For each of these,a cutofffrequency canbe definedthat marks the boundary between low frequencies that are radiated isotropically and the very directional high frequencies.Thus the listener ina roomwith reflecting surfaces ispresented with several "views" of the instrument, andeach view hasa differentspectral distribution. The vibration ofthe walls of thebrass instrument provides another but much smaller directional component.Theamplitude ofthis signal isof the order of 40 dB smaller than the signal radiated directly from the vibrating aircolumn, andso it willusually be masked. However, the longer decay time of thissignal increases thechance of itsdetection. The radiation patternsof this signal are also much different, as well, being quadrupole or higher in order.[Supported bythe Iowa Science Foundation.]
2501 J. Acoust.Soc. Am., Vol. 99, No.4, Pt.2, April1996 131stMeeting: Acoustical Society of America 2501
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
3aAAS. Soundradiation from boxeswith tone holes. GabrielWeinreich (Dept.of Phys.,Univ. of Michigan,Ann Arbor,MI 48109-1120)
The normal modes of a hollow box with one or more sound holes, such as forms the radiating element of a typical string instrument,are combinationsof "wood modes"and "air modes."Wood modeshave an averagefrequency spacing independent of frequency,whereas the averagespacing of air modesis inverselyproportional to frequencyfor frequencieslow enoughto makethe "thin" dimensionof the box smallerthan half a wavelength,becoming inversely proportional to the squareof the frequencyfor frequenciesabove that. As a result,the densityof modesof, say,a violin, is generallydominated by woodmodes at low frequencies and by air modesat high frequencies.The interplayof the two typesof modeshas radical consequences for the directivityof string instruments,in that the directionalpattern can changedrastically within very small musicalintervals, perhaps accounting for the special"flashing brilliance" that suchinstruments exhibit. This talk will oudinethe theoryof theseeffects and supportit with experimentalobservations. [Work supported by NSF.]
9:50
3aAA6. The effect of soundpostremoval on normal mode radiation efficiencyand directivity of a violin. GeorgeBissinger (Phys.Dept., E. CarolinaUniv., Greenville, NC 27858)
The radiativeproperties of individualmechanical normal modes of vibrationof a violincan be calculatedfrom experimental modal analysisresults using boundary element radiation programs that integratethe Helmholtzequation over all surfaceelements. This technique,applied to modalanalysis results for a violinwith and without a soundpost,helps elucidate the acoustic effects of removal of the soundpostboth in termsof the radiationefficiency and directivity of the resultantradiation from eachmode and the overall acousticresponse. Consonant with the experienceof playersand luthiers,soundpost removal has a major effect on the predicted acousticresponse of the violin.Some violin corpus (sans tailpiece and neck-fingerboard)modes that radiatestrongly with the soundpostin placeshow a substantialchange in acousticresponse when the soundpostis removed,which is dependenteither on the strengthof theirmechanical excitation and/or their radiation efficiency [G. Bissinger,1. Acoust.Soc. Am. 97, 3154-3164 (1995)]. Particularattention is paid to the predictedacoustic response changes of the first corpusbending modes at 500 Hz.
10:10
3aAA7. Wrappinga violin with planar near-fieldacoustic holography. Lily M. Wangand Courthey B. Burroughs(Grad. Prog. in Acoust.,Penn State Univ., P.O.Box 30, StateCollege, PA 16804)
Planar near-fieldacoustic holography gives one the ability to reconstructthe soundpressure radiated from a sourcein a three- dimensionalfield from a singletwo-dimensional near-field measurement. Traditionally, only one measurementplane has beenused which givesthe soundradiation in a half-space.In this paper,the near-fieldacoustic holography is modifiedto measurementstaken on six planesconfigured as a "box" surroundingthe source, thereby giving the soundradiation in all directions.Any sourcemay then be put intothis "box"; in thiscase, a violin is usedas the sourcefrom whichsound radiation patterns can be determined.Preliminary simulationsusing the modifiednear-field acoustic holography with six planesare presented.Also, methodsof violin excitationwith a bowingmachine and the positioningof the violin within a measurementframe are described.It is expectedthat many violinsmay be testedwith this setup,therefore providing a tool for assessingthe effectsof differentmodifications to violinson soundradiation. [Worksupported by NSF andan AT&T GRPW Grant.]
10:30
3aAA8. Reproductionof directivity pattern using multiloudspeakersource. Philippe Dirogis, Olivier Wamsfel, and Reni Caussi (IRCAM, I placeIgor-Stravinsky, 75064 Pads, France)
A soundsource can generally be characterizedby threephysical properties: timbre, loudness, and directivity. Although loudspeak- ers give a faithful reproductionof timbre and loudness,their own directivitycan conflictwith the directivityof the sourcethey aim at reproducing.A generalmethod to optimizethe reproductionof any givendirectivity pattern with a set of independentlydriven sourcesis described.At each frequencythe synthesizeddirectivity is obtainedby lookingfor the optimallinear combinationof the elementarysources, from whichthe resultingacoustic field can be predicted.This methodis appliedto a particularsource with 12 loudspeakersgrouped into a few subsetsin orderto fit thefirst spherical harmonics. The comparisonbetween the prediction and the experimentalmeasurements shows excellent agreement. However, the synthesized figures only fit the sphericalharmonics in a limited frequencyrange, which depends strongly on the characteristicsof the electroacousticalset (number,position, and directivityof sources).The interest and the limitations of thismethod are discussed for varioustypes of applications,such as the reproduction of the directivityof instruments,loudspeaker clusters design, and echo cancellation. Finally, an attemptis madeto illustratethe perceptual effectsof the direcfivityby analyzingthe variationsof roomacoustics criteria measured with the differentsynthesized directivity patterns.
10:50-11:05 Break
2502 J. Acoust.Soc. Am., Vol. 99, No.4, Pt. 2, April1996 131stMeeting: Acoustical Society of Amedca 2502
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
11:05 array was placedon a sphericalsurface with a 2-m radius.The micro- phonesused to measurethe radiationfield wereplaced every l0 degfrom 3aAA9, Sound intensity patterns from two basshandbells. Edward the top of the piano to 130 deg on the lower side of the piano. The R. Manselland ThomasD. Rossing (Dept. of Phys.,Northern lllinois microphoneswere roundedevery 10 deg from 0 deg to 350 deg on the Univ., De Kalb, IL 60115) horizontalplane. A referencemicrophone was placed at the centerof the The soundintensity patterns of two GI handbellswere investigated. sphereon whosesurface the measurementmicrophone array was placed. One bell is aluminum and the other is traditional bronze. The results in- The spatialimpulse responses were obtained as follows:(1) The power dicatethat the aluminum bell has a betterradiation efficiency for the(2.0) spectraof boththe radiatedsound in all directionsand the referencesound modefundamental (f-49 Hz). Soundintensity was mappedfor the two at the referencemicrophone were calculated; (2) the ratioof the radiated tunedmodes of vibration:the (2.0) and (3.0) modes.The paramelricra- spectrumto the referencespectrum was taken;and (3) minimumphase diation(twice the modefrequency) was significantfor bothmodes. espe- directivity filters were made using the power spectrumratios obtained cially the (3.0). The measurementof bothactive and reactive sound inten- throughthe above procedures.These directivity impulseresponses and sity revealsa betterpicture of the soundfield than soundpressure alone. filtersare usefulfor binauralroom simulations including piano sounds, and Both of the •ells are poor radiatorsof the fundamentalbecause of their for synthesizingpiano tonesin a computer. smalldimensions compared to the soundwavelength in air. [Both bellson loanfrom Maimark, inc.]
11:35 11:20 3aAAII. Modes of vibration and direcfivity of guitars. Eric T. 3aAA10. Directivity analysisof piano sounds. HidetoshiNakashima Watson (WatsonAcoustical Consulting, 13114 Creekview Park Dr.. IDept. of InformationEng., KogakuinUniv.. Rm. 5-603. Nakano-cho Houston,TX 77082) and ThomasD. Rossirig (Northernillinois Univ., 2665-1, HachiojiCity, Tokyo, 192 Japan),Franck Giron (Ruhr Univ., DeKalb, IL 601 BochumD-44780, Germany). and Mikio Tohyama (Kogakuin Univ., HachiojiCity, Tokyo, 192 Japan) An acousticguitar radiates sound primarily from the top plate,the back plate, and throughthe soundhole, leadingto a rather interestingsound The authorsinvestigate the directivityof soundsradiated by a piano field [E. T. Watsonand T. D. Rossing,J. Acoust.Soc. Am. Suppl.I 83, andderive spatial impulse responses for representationof the pianodirec- S 119(1988)]. The modesof vibrationof theguitar body, including the top tivity in spatialdirections. To obtainthe radiationpatterns of pianosounds. plate, the back plate, and the enclosedair, and the radiationpatterns that the radiationfield was measured in an artecholeroom where a microphone resultfrom excitingthese modes in an anechoicroom, are de•ribed.
WEDNESDAY MORNING, 15 MAY 1996 NATIONAL PARKS, 8:00 A.M. TO 12:05 P.M.
Session 3aEA
Engineering Acousticsand Signal Processingin Acoustics:Acoustics for Hands Free Communications
James E. West, Chair Bell Laboratories,Lucent Technologies, 600 MountainAvenue, Murray Hill, New Jersey07974
Chair's Introduction4:00
Invited Papers
8:05
3aEAI. A DSP implementationof sourcelocation using microphone arrays. Daniel V. Rabinkin,Richard J. Ranomeron.Art Dahl, JoeFrench, James L. Flanagan (Ctr. for Cornput.Aids for IndustrialProductivity, Rutgers Univ., P.O.Box 1390,Piscataway, NJ 08855-1390), and Michael H. Bianchi (Bell Commun.Res., Morristown, NJ 07960-6438)
The design,implementation, and performance of a low-cost,real-time DSP systemfor sourcelocation is discussed.The system consismof an eight-elementelectret microphone array connected to a SignalogicDSP daughterhoardhosted by a PC. The system determinesthe location of a speakerin theaudience in an irregularlyshaped auditorium. The auditoriumpresents a nonideal acoustical environment;some of the walls are acousticallytreated but there still exist significantreverberation and a large amountof low- frequencynoise from fans in theceiling. The source location algorithm is implemented in a two-stepprocess: The first step determines timedelay of arrival(TDOA) for select microphone pairs. A modifiedversion of the cross-power spectrum phase method [M. Omologo andP. Svaizer,Proceedings of IEEE ICASSP 1994 (1EEE, New York, 1994), pp. 11273-11276] is used to computeTDOAs and is implementedonthe DSP daughterboard. The secondstep uses the computed TDOAs in a least-mean-squaragradient descent march algorithmimplemented onthe PC to compute a location estimate. [Work supported bya contractwith Bell Communications Research.]
2503 d. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society o1: America 2503
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 3aEA2. Acousticecho cancellation for duplexaudio communication,Steven L. Gay (Bell Labs.,Lucent Technologies, 600 MountainAve., Murray Hill, NJ 07974)
Thispaper reviews the problemsassociated with the applicationof acousticecho cancellation to duplexhands-free audio com- munication.The morepopular approaches to thesolution of theseproblems are reviewed as well.In particular,the problems discussed includethe effects of coramunicationchannels on thehuman perception of echo,characteristics of the acoustic echo path, double-talk, and stability.The methodswhich address these obstacles are fast-converging,low-complexity long adaptivefilters, double-talk detectors,and suppressionand clippingtechniques.
9:05
3sEA3, Low cost methodsfor mitigating hands-freeacoustics problems. PeterL. Chu (PictureTelCorp., 222 RosewoodD•., Danvets, MA 01923)
Keyproblems in hands-freeacoustics for teleconferencingare acoustic echo cancellation, reverberation, noise, varying amplitude, andrestricted audio bandwidth. None of theseproblems can be completelysolved via low-costmethods, but their nuisancecan be significantlyreduced. For acoustic echo cancellation, a sub-band approach has been found to workwell, wherethe speech is divided up into manybands and echo cancellation occurs individually on eachband. Reverberation in speechpickup may be significantly reducedvia a simpletwo dipole,automatically steered array which forms a dipolepattern which may be electronicallyrotated a full 360 deg.Background noise from fans may be suppressedusing spectral subtraction techniques. Varying amplitudes of speechmay be addressedby meansof a voice-activatedAGC (automaticgain control), where the voice detector eliminates pumping artifacts usually foundin agressivcAGC schemes.Finally the useof 7-kHz digitalaudio compression schemes alleviates the problemsof muffled soundingspeech due to the 3.4-kHz restrictedaudio bandwidth found on telephones.
ContributedPapers
9:35 simulations.To measuremicrophone array performancein more realistic conditions,a flexible,experimental microphone array has beendeveloped 3aEA4. Talker direction finder system implemented with cardioid basedon digitalsignal processing technology. This arrayis flexibleenough beams and DSP algorithm. John C. Baumbauer,Jr., Alan D. Michel, to permitthe implementationof a wide varietyof signalprocessing strat- and JeffreyP. McAteer (Bell Labs., LucentTechnologies, 6612 E. 75th egiesand arraygeometries. In this paperthe arraydesign will be described St., Indianapolis,I/q 46250) andthe performanceof thisarray in the variable-acousticslistening room A prototypetalker direction finder (TDF) algorithmhas been devel- at the National Research Council will be discussed. opedthat will rapidlylocate a newtalker (within 200-400 ms)or tracka movingone. For mostroom configurations,the algorithmhas an inaccu- 10:20 racy meanof lessthan 10ø of azimuthalangle and a standarddeviation of 7 ø. The TDF providesfull room,360 ø coverage.A prototypewhere the 3aEA6. Image-derivedsecond-order differential microphoneon a TDF physicallyrotates a cameratoward the talkerhas demonstrated the finite baffle. Gary W. E!ko (Bell Labs.,Luccnt Technologies, 600 TDF's robustnessin difficult(i.e., realistic) noisy and reverberant environ- MountainAve., Murray Hill, NJ 07974) ments.The physicalinputs to the TDF are three small and inexpensive onmidirectionalmicrophone elements that are all placedwithin a 1-in. A singlefirst-order dipole microphone placed close to a reflectingplane circle, allowing inconspicuousdesign into a consumerproduct_ Three resultsin a unidirectionalsecond-order differential microphone. In practice /a-law codecsprovide Inputs to the digital signal processorwhere the an infinitereflecting plane is not attainableand it is thereforeof interestto TDF's new least-mean-squares-typeadaptive algorithm resides. The over- examinethe effectsof usinga finite reflectingsurface on second-order all systemdesign is summarized,including preprocessing to reducethe image-derivedmicrophones. This talk will presentresults obtained in the effectsof noiseand reved>eration.The adaptivealgorithm, which employs investigationof a finite reflectingsurface size by usingthe solutionto the redundant"pattern matching" to six cardioid acousticpickup beams wave equationfor scatteringand diffraction from an oblatespheroid. The formedfrom the threemicrophone element inputs, is thenpresented. The particularsolution that is investigatedis for the caseof an infinitesimally TDF can provide enhancedsolutions for teleconferencingand speaker- thin oblatespheroid, the disk. Resultsshow that the responseof a first- phoneacoustic systems. The algorithmcould be usedto providedirectional order bidirectional sensor over the disk is sensitive to sensor location as informationto steeran "adaptivebeamformer" for advancedaudio pickup well as to disk sizerelative to the acousticwavelength. For a centrally applications. locatedimage-derived second-order microphone, the differentialsensor responseapproaches a second-orderresponse at a frequencywhere the reflectingbaffle size is at leastone-half the acousticwavelength. Experi- 9:50-10:05 Break mentalresults for bothcircular and rectangula•baffle geometries will also be shown.
10:05 10:35 3aEAS. A flexible experimentalmicrophone array. JamesG. Ryan (Inst. for Microstract.Sci., Natl. Res. Council, Ottawa, ON KIA 0R6, 3aEA7. Practical applicationsof first- and second-orderdifferential Canada) microphonesin personal computer (PC) multimedia products. JeffreyP. McAtcer (Bell Labs.,Lueent Technologies, 6612 E. 76thSt., P. Soundpickup for hands-freecommunications often requires the micro- O. Box 1008,Indianapolis, IN 46206) phoneto be locatedat a largedistance from the talker.However, in typical environments,the resulting speech signal is corruptedby reverberationand Directionalmicrophones are usedin PC voiceand telephony applica- noisewhich degrade perceived voice quality and impairthe operationof tionsto reducethe pickupof noiseand reverberation,as well as reduce automatic speech recognizers.Microphone arrays have been shown to loudspeaker-to-microphoneacoustic coupling. Differential-type directional providesubstantial improvements in predictedvoice quality in computer microphonesare popularbecause of their smallsize and relatively low
2504 J. Acoust.Soc. Am., VoL 99, No.4, Pt.2, April1996 131stMeeting: Acoustical Society of Amedca 2504
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 cost.This talk focuseson howdifferential microphone technology has betweensource and receiver. Furthermore, these teleconferencing environ- beenused in newproducts and solutions developed by AT&T intelligent meritsmay featurecommunication over multipleaudio channels. The acousticsystems for thePC multimediaindustry. soundquality in suchenvironments is typicallydegraded due to acoustic reflectionsfrom nearby walls, people, and objects. These undesired echoes 10:50 mustbe removedif oneis to maintaina highsound quality. In thiswork the problemof acousticecho cancellation is examined.The techniquefor 3aEA8. Predictabilityof acousticaleffects of microphoneports in acousticecho cancellationis basedon sub-banddecomposition. For a the telecommunicationsequipment. David M. Yeager (Acoust. reverberantroom, the sourceto receiverimpulse response is computedby Technol.Lab., Radio ProductsGroup, MotorolaCorp., 8000 W. Sunrise an image- basedmethod. The influenceof scatteringfrom objectswith Blvd., Fort Lauderdale,FL 33322) high acousticalcontrast is computedby a Pad6 approximantsbased Low-cos!electre! microphones are ubiquitousin telecommunications method.A modelfor the impulseresponse resulting from nonideal images, equipment.They are capableof providingnearly ideal response,while frequency-dependentwall impedanceand acoustic scattering is presented. oftenemployed as pointreceivers. However, uniform response is not al- Resultscompare single and multiplescattering effects. The variationsin waysoptimal, especially for digitalapplications or microphonearrays, nor scatteringamplitude due to scatterermotion are examined.The impactof is it easilyachievable given mechanicalpackaging constraints. It is there- thesefeatures on echo-cancellerperformance is evaluated. fore essentialfor a givendesign to incorporatefrequency-dependent ef- fects of the microphonehousing. Frequency shaping is typically done electrically,but acoustical filters can be realizedby appropriateselection of seriesor parallelcavities al the microphone.Damping mustbe accounted for by estimatingthermal-viscous effects of the cavity openings,or by 11:55 introducingflow-resistive materials for whichacoustical parameters are 3aEAII. Considerationsin applying noisecancellation techniques to knownor canbe measured.The frequencyeffecls of microphonehousing telephones.Alan S. Nasa',Chaim Bitman (Dept.of Mech.Eng., Cooper geometriescan be modeledusing any one of severaltechniques, the choice Union, 51 Astor Pl., New York, NY 10003), and Daniel R. Raichel dictatedby the desiredaccuracy, complexity of the physicalrealization, (CooperUnion, New York, NY 10003and City Univ. of New York, New and availableresources. in this paper,two predictionmethods will be York, NY) discussed.First, classical lumped- and distributed-element models will be describedalong with analysesobtained using MATLAB. Second, some pre- liminary resultsof numericalmodels using boundaryor finite element The inteiligibility of voice transmissionthrough a telephonecan be methodswill be presented. severelyaffected by the presenceof excessivebackground noise. Accord- ingly,a systemwas designed to incorporatean auxiliarymicrophone into the receiverof an ordinarytelephone handset. This microphoneis strate- 11:05
3aEA9. Acoustic echo cancellationby short-time Fourier transform is subtractedfrom that of the receiverthrough a circuitincorporating three and cross-spectrumprocessing. Takatoshi Okuno (Dept. of op-ampsto producea signalthat containssignificantly less background InformationEng.. Kogakuin Univ., Rm. 5 601. Nakano-machi2665-1 noisethan the originalsignal. The correctedsignal is thenrelayed through Hachioji City, Tokyo, 192 Japan),Hirofumi Nakajima, Mikio Tobyarea the telephonein the samemanner as that for the receiverin an ordinary (KogaquinUniv.. Tokyo. Japan), and Hirofumi Yanagawa (Pioneer telephone. ElectronCorp.. Tokorozawa, Saitama. Japan) gicallyplacedtopickupambientnoise. Thesignal fromthismicrophone Acousticecho cancellets have problemsin estimatingroom transfer functions(TFs) for acousticecho paths when the conditionsare noisyin the acousticspace. In this article, the possibilityof estimatingthe room 11:50 TFs is investigatedby takinga time-frame-averagedcross spectrum(CS) betweenthe input signalsand error signals,which are composedof echo 3aEAI2. Objective and perceptual characterizationof microphone signalsthrough the echo path and the surroundingnoise. First, the short- arrays for virtual acousticsapplications. Olivier Warusfel,Rozenn timeFourier transforms (STFTs) and cross spectrum for boththe input and Nicol (IRCAM, ! PI. Stravinsky,75004 Paris, France),and Yannick errorsignals are taken.The TFs canbe estimatedfrom the ratioof the CS Mahieux (CNET, 22307 LannionCedex, France) to thepower spectrum of the inputsignal. since it canbe expectedthat the time-frame-averagedCS componentsbetween the input signaland the Microphonearrays represent an attractivesound pickup solution for surroundingnoise will be zero.It wasreconfirmed by computersimulation virtualacoustics applications where a highrejection of the acousticenvi- that the echosignals can be suppressedas the averagingprocess goes on, ronment(ambient noise and reverberation) is neededfor minimizingarti- even in noisyconditions. The roomTFs could be estimatedas long as the factsduring the postprocessing of the sound(filtering, spatialization, arti- S/N ratio was about 10 dB. This STFT-CS methodrequires more calcula- ficial reverberation).This study intends to evaluate. on the basis of tions than a time domain method, such as the RLS method; however, it can simulationsand experiments.different prototypes of microphonearrays be implementedusing general purpose FI• boards.Adaptation for rapid designedat CNET. The differentsteps of the arrayprocessing (i.e,, band TF changesis goingto be investigatedin the near future. filteringof subarrays,sensors weighting, beamforming. and steering) are implementedon a signalprocessing prototyping environment. This pro- 11:20 gramis usedto synthesizethe impulse response of themicrophone array in a real acousticfield. The inputsignals are the impulseresponses succes- 3aEAI0. Simulation and cancellation of echoes in a reverberant sivelymeasured between a sourceand each sensor location of thearray in room. VineetMehta, Ming-Yi Lai, and Charles Thompson (Ctr. for Adv. realrooms. The objectivecharacterization of the array is basedon classical Computationand Telecommum,Univ. of Massachusetts,Lowell, MA criteriaused in roomacoustics and on the analysisof the time-frequency 01854) envelopeof thelate reverberation. The perceptualanalysis is performedby The evolutionof voice communicationstechnology promises high- convolutionof the array responseswith anecboicsignals. A parametrical fidelity teleconferencingsystems without encumbering the userwith hand- •tudy is undertakenin order to study the influenceof the •eometrieal and held devices.The freedomof movementprovided by hands-freedevices signalprocessing characteristics of thearray. Theoretical and experimental yields dynamicacoustic environments and allows for greaterseparation resultsare compared and discussed. [Work supported by CNET.]
2505 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society of Amedca 2505
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, 15 MAY 1996 FOYER BETWEEN CELEBRATION HALL & REGENCY BALLROOM, 10:00 A.M. TO 3:00 P.M.
Session 3aED
Education in Acoustics: Undergraduate Research Poster Session
Victor W. Sparrow,Chair GraduateProgram in Acoustics,Pennsylvania State University,157 HammondBuilding, UniversityPark, Pennsylvania16802
ContributedPapers
All posterswill be on displayfrom 10:00a.m. to 3:00p.m. Contributors will be at theirposters from 10:00a.m. to I:00 p.m.To allow for extendedviewing time, posterswill remainon displayuntil 3:00 p.m.
3nED1. Sound velocity measurementsin mixtures of air bubbles in basedon the analogcircuit simulatorHSPICE. The synthesizeriRael castoroil. Colin P. Day andMurray S. Korman (Dept.of Phys.,United eta/., J. Aconst.SOC. Am. 97, 3430(A) (1995)] usesa transmission-line StatesNaval Acad.,Annapolis, MD 21402) analogmodel of the vocal tract with the specificationof the type and Experimentalmeasurements of the phasespeed are performedin a locationof dependentor independentsources (voltage or current).Model- medium of air bubbles in castor oil. Castor oil has been chosen as the host ing involvedplacing noise sources in the vicinity of the maximumcon- liquid due to both its densityand soundspeed being closely matched to strictionand at other locationsin the vocal tract. A voicing source that of water.The viscosityof castoroil is about1000 timesgreater than (KLGLOTr88)was used for the voicedfricatives. Synthesized spectra waterwhich allows bubbles to rise relativelyslowly in a cylindricalcon- matchednaturally spoken spectra of/s,sh,v,z.t by placingtwo or three tainer.The phasespeed will be measuredin an apparatussimilar to the voltagesources near the constriction and near the lipsfor/s,z,v/, andat 1.2 standingwave tube setup repone, d by E. Silberman[J. Acoust.Soc. Am. cm awayfrom the lips for/sh/. The current(monopole) source was not 29, 925-933 (1957)].We areinterested in comparingour resultswith the usefulin synthesizingthese fricatives. Results for Iv,z/were satisfactory phasespeed theory that was reportedby K. W. Commanderand A. Pros- usingboth voicing and noise sources even though Ivl wasspectrally fiat peretti[J. Acoust.Soc. Am. 85, 732-746 (1989)].The volumevoid frac- tion ,8 (of air volumeto totalmixture volume) is estimatedby electronic above1.5 kHz. Themodel did notsuccessfully synthesize/f, th/; this may measurementswhich involvemeasuring the capacitanceof a cylindrical be attributedto the seeminglymore complexradiative and turbulentbe- coaxialcapacitor in air, in oil, and in bubblyoil. haviorfor thesesounds. [Work supported by NSE]
3nED2. Frequency and amplitude of vibration of reeds from American reed organs as a function of pressure. Philip D. Koopman,Chad D. Hanzelka,and JamesP. Cottingham (Phys.Dept., Coe College,Cedar Rapids, IA 52402)
The frequencyand amplitude of vibrationof a representativesample of 3aEIM. Undergraduate research projects in noise and vibration reedsfrom Americanreed organshave been studiedas functionsof the controlcourses. L. Mongeauand I.D. Jones (Schoolof Mech.Eng., (negative)static pressure difference between the interior and exterior of the PurdueUniv., 1077Herrick Labs., West Lafayette, iN 47907) windchest.Over a pressurerange that includes the normal playing pressure of the instrument,the frequencytends to decreasein an approximately Theintegration of projectsin undergraduatenoise and vibration control linear fashionwith increasingpressure difference, but someanomalous coursesallows the students to creativelyapply the course material to prac- effectsare observedat higherpressures. Effects of constrictionsto the airflow,simulating the effectof a partiallyopened pallet, have also been tical problems.The projectsalso provide the opportunityto investigate studied. sometechnologies and concepts that are beyondthe scope of the lecture material.For a numberof years,interdisciplinary projects have been real- ized in the contextof the noiseand vibration control courses offered by the Schoolof MechanicalEngineering at PurdueUniversity. Juniors and se- 3nED3. A transmission-linemodel of the vocal tract during fricative niorsin mechanical,electrical, and industrial engineering work in teamsof production. JesseIbarra (Dept.of Elec.Eng., UCLA, 405 HilgardAve., threeto five students.The objectivesof eachteam are definedin collabo- Los Angeles,CA 90095) rationwith selectedfaculty members and practicingengineers from the The purposeof this studyis to examinethe articulatory-to-acoustic localindustry, designated as "customers."The projectsculminate during mappingof the fricatives/s,sh,z,f,v,th/. The studyutilizes MRi 2506 d.Acoust. Soc. Am., Vol. 99, No.4, Pt.2, April1996 131stMeeting: Acoustical Sociely of America 2506 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, 15 MAY 1996 CELEBRATION A, 8:00 A.M. TO 12:05 P.M. Session 3aNS Noise: Current Issues in Automotive Noise Paul R. Donavan, Chair Noise and VibrationLaboratory, General Motors, GM ProvingGround, Building 24, Milford, Michigan 48380 Chair's Introduction--8:00 Invited Papers 8:05 3aNSI. Modern noiseand vibration designof internal combustionengines. MichaelE Albright (RoushAnatrol, Inc., Livonia, MI 48150) In recentyears. new enginedesign for the transportationindustry has occurredin an atmosphereof strictcompliance with aggressivenoise and vibration performance targets. The inevitableresult is a growingarsenal of tools,methodologies, and experience in thedesign of quiet,smooth, high-performance engines. In thisdiscussion, some of thekey issuesfacing engine designers responsible for noiseand vibrationperformance will be introduced.The discussionwill focuson the applicationof someof the neweslexperi- mentaland analytical tools which are applied to suchcomplex issues as combustion noise, crankshaft to blockinteraction, valvetrain, andpiston to cylindercontact forces. A particularemphasis will be placedon recentdevelopments in combustionnoise control and the future of the wholly analyticalengine noiseand vibrationsignature simulation model. 8:25 3aNS2.A surveyof automobilewind noise. AlbertR. George (SibleySchool of Mech.and Aerospace Eng., 106 RhodesHall, CornellUniv., Ithaca,NY 14853) and JohnR. Callister (Cornell Univ., Ithaca,NY 24853) The studyof automobileaerodynamic noise is a field that hasgrown rapidly in the pastdecade. Automobile manufacturers and independentresearchers now havea betterunderstanding of the mechanismsof automobileaerodynamic noise. Methods of making windnoise racasurcmenls have been improved. Some fundamental wind noise reduction measures have been developed. In thispaper, the basicmechanisms of automobileaerodynamic noise generation are explained.Current wind noisemeasurement instrumentation andtechniques are reviewed.Some wind noisereduction measures found on today'sautomobiles are discussed.Finally, a prediction methodfor an idealizedcase of automobileaerodynamic noise is shown.Knowledge of theseadvances will help automobilemanu- facturersto designquieter vehicles. 8:45 3aNS3.Flow noisein automotiveheating, ventilation, and air conditioningsystems. Gerald C. Lauchle (GraduateProgram in Acoust.and Appl. Res.Lab., PennState Univ., P.O. Box 30, StateCollege. PA 16804} Acousticnoise generated by a typicalautomotive heating, ventilation, and air conditioning(HVAC) systemcan be dominatedby unsteadyflow and turbulence. A comprehensiveflow field and acoustic field study has been conducted experimentally on a stand-alone HVAC systemoperating in its maximumair conditioningmode. Acoustic intensity field mappingwas conductedin an anechoic environment.Detailed flow visualizationswere conducted underwater on an opticallyclear system operating at prototypicalvalues of the Reynoldsnumber. The bloweris the dominantlow-frequency source of noise,while at higherfrequencies, additional flow noise sourcesexist. These include high shear regions within the ducting,separated flows off of flow obslrnctions,and the exit flow from registervents. Flow visualizationsof the blowerinternal flow field werealso conducted on a three-times-largeroptically clear model of theblower using underwater particle tracking techniques. The resultsidentify significant regions of inefficientflow, such as blade passageflow separation, reentrant flow, and rolaling slall. Collectively, these lead Io pooraerodynamic performance as well as noise. [Worksupported by FordMotor Co. andis drawnfrom the thesis research of formerstudents Timothy Brungart, George Denger, Lori Perry,and Mike Sullivan.] 9:05 3aNS4.Vehicle interior noise. !. Noisepaths: Structure-borne and airborne. AlanV. Parret! (Noise& Vib. Ctr.,General Motors ProvingGround, Milford, MI 48380} andRichard G. DcJong (Eng. Dept.,Calvin College, Grand Rapids, MI 40546) This papergives an overviewof vehicleinterior noise, its characteristics,and control methods. There is a widevariety of noise problemsencountered in automobilesdue to thesources involved and lhe rangeof operatingconditions. Depending on theseoperating conditions,either airborne or structure-bornenoise can he dominant.The complexitiesof automotivestructures mean that a varietyof analysistechniques needs to be appliedto theproblems, from the early design stage through to vehiclehardware development. These includeboth analytical and empirical methods. Examples are given of automotiveairborne and structure-borne noise problems in a 2507 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April1996 131st Meeting:Acoustical Society of America 2507 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 source,path, receiver framework. Source characteristics (tonal or broadband),problem frequencies, available analysis techniques, and practicalsolution methods are discussed.Solutions include quieting the source,using isolation at mountingpoints, and dampingand trim materialsin the vehicleinterior. In practicalterms, noise control solutions need to be balancedto comply with overall vehiclecost, nmss,and otherperformance constraints. 9:25 3aNS5. Vehicleinterior noise.II. Modeling. RichardG. Delong {Eng.Dept., Calvin College,Grand Rapids, MI 49546) and Alan V. Parrerr (GeneralMotors Proving Ground, Milford, MI 48380) An overviewis presentedof severalmethods available to determinethe interiornoise in a vehicleunder given operating conditions. Issuescovered include: how and whenthese methods can bestbe applied;the limitationsimposed by the methodsthemselves; and someof the difficultiesassociated with modelingvehicle structures.Current modeling methods used in automotivenoise problems includefinite dement,boundary deznent, statistical energy, and power flow methods.Each method has domains of applicability,but morespecific to the automotivedesign process, they havedifferent applicability at differen stagesin the designcycle. There are practicallimitations, such as the lack of detailearly in thedesign process which presents difficulties for deterministicmethods at high frequencies.In contrast,later in the processwhen details are available,there may be the needfor morespecific answers to design trade-offsthan statistical methods can give. Examplesare givenof somepractical problems encountered in vehiclenoise modeling, illustratingareas where improvements are still needed. 3aNS6. On the developmentand applicationof automotivesound package materials. PranabSaha and John Chahine (Kolano andSaha Engineers, Inc., 5095 WilliamsLake Rd., Waterford,MI 48329) It is importantto understandnot only the noiseproblem, and the functionaland aestheticissues of an automobile,but alsothe environmentaland competitive issues of the industryto developappropriate sound packages that will meetthe customer requirements. The vehiclemanufacturers and their suppliersdo so within the boundsof the materialand processdevelopment technology that is available.The evolutionof the basicautomobile design and constructionalso has a significantimpact on the soundpackage devel- opment.This may requirean entirelynew type of materialapplication or an innovativeprocess and product.The paperreviews differenttypes of soundpackage and processdevelopments that have evolvedover the yearsin somespecific applications. These developmentsnot only providebalanced acoustics inside the automobile,but alsomeet various challenges of the industry. 10:0'• 3aNS7. Light vehicle exterior noise: Measurement, regulation, tires, and pavement. Paul R. Doneven and Richard F. Schumacher(Noise and Vib. Ctr., GeneralMotors Proving Ground, Milford, MI 48380) Exteriornoise is the only acousticattribute regulated for passengercars and light trucks.The primaryprocedure used to quantify this noise is an outdoorpassby test conductedunder full-throttle acceleration.Unless specifiednoise levels are met under this procedure,a vehiclemay not be sold in a given marketjurisdiction. Recent reduction of Europeanregulatory limits by 3 dB has re-enforcedmany of the technicalchallenges faced in designingand testingvehicles to meetthese new requirements.These challenges include:better understanding and control of testand environmental variables, more accurate methods of noiseprediction, and improved techniquesfor isolatingand reducingindividual source conuibution. In recentinvestigations, sound intensity has been employed to isolatetiredpavement interaction noise for vehiclesunder passby conditions. This hasled to the determinationthat tires can produce significantlyhigher noise levels under the torqueof accelerationthan under cruise conditions. As a result,tires are often the majornoise sourcewhen the total vehicle noise approaches the new regulatorylimits. This paperreviews the variablesassociated with the passby test procedure,the effectsof vehicleacceleration on tire/pavementinteraction noise, and the needsfor improvedpredictive methods. 10:25-10:35 Break ContributedPapers 10:35 vehicles in motion were first examined to establish the correlation between surfacetype and sourcespectrum and level. Sourcelevels were approxi- 3aNS8. The effect of surface variability on the short-range mately I dB higherat SAE sitesthan at ISO sites.Two-microphone meth- propagation of tire/road interaction noise. Denny M. B. Yim (Roush Anatrol, 935 BeneelsAve., Sunnyvale,CA 94086) and J. StuartBolton odswere thenused to estimatethe acousticimpedance of boththe ISO and (PurdueUniv., West Lafayette,IN 47907-1077) SAE surfaces.The surfaceimpederices were usedtogether with measured tire sourcespectra and sound propagation theories to calculatethe passby The objectof thiswork wasto identifythe originof differencesbe- level variabilitythat couldbe attributedto variationsin testsite acoustic tween soundlevels measuredon two track typesused for standardized impedance.It wasfound that differences in propagationtransfer functions motor vehicle passbynoise tests: i.e., the ISO and SAE surfaces.The for theISO andSAE surfaceswere on theorder of only0.3 clB.Thus it was measured differences could result either from the effect of the road surface concludedthat the differencesin passbylevels measured at ISO and SAE on tire/roadinteraction noise generation, or fromsurface sound absorption sitesresulted primarily from differences in tire/roadinteraction noise gen- differences.Near-field intensity data measured at the tire/roadinterface on eration. 2508 d. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, Apdl1996 131stMeeting: Acoustical Society of America 2508 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 cific roughnessacross frequency to yield an overallroughness measure. Signaldecomposition is performedwith a bank of overlapped,critical 3aNS9. Two-microphonemeasurements of the acousticalproperties bandwidth,bandpass filters. Because the signal in each channelis well of plane asphaltsurfaces in the presenceof wind and temperature representedby a smallnumber of harmonicallyrelated, narrow-band com- gradients. Troy J. Hartwig, i. Stuart Bolton (1077 Ray W. Herrick ponents,it is asstunedthat specificroughness can be determinedfrom the Labs., School of Mech. Eng., Purdue Univ., West Lafayette, IN peaksin the magnitudespectrum of the envelopesignal. A maskedthresh- 47907-1077),and Denny M. B. Yim (RoushAnatrol, Sunnyvale,CA old estimatefrom the inputsignal is usedto predictaudibility of envelope 94086) fluctuationin each filterbankchannel. Channels whose envelope fluctua- When performingtwo-microphone measurements of surfaceproper- tion falls below thresholdare assumednot to contributeto overallrough- ties, an algorithrais usedto find the propertiesthat give the best fit be- ness,and are thereforediscarded. Specific roughness values of the remain- tweenmeasured and predictedtransfer functions between the two micro- ing channelsare combinedwith a power-lawmodel, yielding an overall phones.Recently it was found necessaryto adjustcertain geometrical roughnessmeasure rE. Terhardt.Acustica 30, 201-213 (1974)].Results of parameters,e.g., ihe .separationbetween the sourceand microphones,to subjectivetests of powertrainsounds are presentedwhich validatethe obtainan acceptablefit betweenmeasured and predicteddata measured performanceof the model. [Work supported by FordMotor Company.] over asphaltsurfaces. It washypothesized that it was necessaryto allow thatvariation to accountfor the effectsof wind and temperaturegradients. 11:35 ThaEhypothesis has been confirmedby using ray tracingtechniques to simulatethe effect of wind and temperaturegradients on two-microphone 3aNS12, Modeling of noise spectra of axial flow fans in free field, measurements.It has been found that near-surfacegradients have signifi- ShigongSu (Dept.of Mech.Eng., Wayne State Univ., Detroit, M148202), cant effectson both the angle of specularreflection and the path length Seen E Wu (Wayne State Univ., Detroit, MI 48202), and Hemant S. differencebetween the directand reflectedarrivals. These effects are par- Shah (Ford Motor, Dearborn,Ml 48120) ticularlyimportant when estimating the propertiesof high impedancesur- A semi-empiricalformula for predictingthe noisespectra of axial flow facesowing to the rapidchange of the reflectioncoefficient at near-grazing fans in a free field is developed.In derivingthis formulationit is assumed anglesin that case.Nevertheless, it will be shownthat the impedanceof that soundradiation from an axial flow fan is primarilydue to fluctuating asphaltcan be estimatedaccurately if the effect of ray curvalureis ac- forcesexerted on the fan blade surface.These fluctuating forces are cor- countedfor when fitting measuredand theoreticaltransl•r functions. relatedto thetotal lift forceexerted on the fan blade,and is approximated by pressurepulses that decay both in spaceand time. The radiatedacoustic 11:05 pressureis thenexpressed in termsof superpositionof contributionsfrom thesepressure pulses, and the correspondingline spectrumis obtainedby 3aNS10. The acoustic characteristicsof automotive body seals, taking a Fourier seriesexpansion. To simulatethe broadbandsounds, a RobertDanforth and Luc Mongeau (Schoolof Mech. Eng.,Purdue Univ., normaldistribution-like shape function is designedwhich divides the fre- 1077 Herrick Labs., West Lafayette,IN 47907) quencyinto consecutive bands centered at the bladepassage frequency and The acousticcharacteristics of robberprimary bulb weatherseals, used its harmonics.The amplitudeof this shapefunction at each centerfre- aroundroad vehicle doors to isolatethe passenger compartment from water quencyis unitybut decays exponentially. The decayrate decreases with an infiltrationand air leaks, were investigatedexperimentally. Short seal increasein the numberof bands.Thus, at high frequencies,the narrow sampleswere mountedwithin the testsection floor of a small,quiet, low- bandsmerge to form a broadband-like spectrum. The noisespectra thus speedwind tunneladjacent to a soundproofanechoic enclosure. The ge- obtainedare comparedwith measuredones from four differenttypes of ometryof the fixturehosting the samplesapproxilnated that of a typical axial flow fansrunning under various conditions. vehicledoor gap. The resultsdemonstrated the importanceof small air leaksand thatof the flow-inducedHelmhohz resonance of the doorcavity 11:50 on the acousticperformance of the seal assembly.The noise reductionof perfectlysealed systems appeared to be slightlyhigher with a flow exci- 3aNSI3, Sound radiation from a centrifugal blower in a free field, tationthan that measuredwith a randomacoustic excitation using a rever- ShigongSu (Dept.of Mech. Eng.,Wayne State Univ., Detroit,M148202), bernlionroom method.The experimentalresults were comparedto the SeanE Wu (WayneState Univ., Detroit,MI 48202), and Morris Y. Hsi predictionsfrom a two-dimensionallumped-element analytical model (Ford Motor Co., Dearborn, MI 48120) basedon the assumptionthat the seal behaveslike two limp membranes A new fommlalion for predictingsound radiation from a centrifugal separatedby a closedcavity. The influenceof seal compression,rubber blower in a free field is derived. The fundamental difference between the properties,and cavitygeometry were investigated.[Work supportedby presentformula and the previouslyderived ones is that the formerconsid- CooperIire andRubber Company.] ers a new monopole,while the latter assumesthe dipoleas the primary source.For an axial flow fan or a rotor bladeunder steady flow condition, 11:20 theusual monopole source proportional to (poa•On/sit)is negligible [Sid- don,J. Acoust.Soc. Am. 53, 616-633 (1973)].However, for a centrifugal 3aNS!I. A model for predicting roughnessof powertrain sound. B. blowerthe monopole source induced by Coltollsacceleration (•o x vt) can- JohnFeng (ScientificRes. Lab., Ford Motor Co., 20000 RotundaAve., not be neglectedbecause of a large inclinationangle of the impeller.With Dearborn,MI 48121), Gregory H. Wakefield (Univ. of Michigan,Ann the inclusionof this monopolesource tenet, the formula yields a depen- Arbor, MI 48109), and Norman C. Otto (Ford Motor Co., Dearborn, MI 48121} denceof the radiatedsound power on the fourth powerof the a•imuthal speed,which agrees with the experimentaldata [Maling, J. Acoust.Sue. The semanticdimension of rough/smoothcan be an importantfactor in Am. 35, 1556-15640963); Neise,J. SoundVib. 43, 61-75 (1975)].The customerpreference of automotivepowertrain sound. With this in m.;nd,a resultingformula can be usedto derivethe radiatedsound power spectrum new modelis proposedfor predictingroughness of powertrainsound. The usingthe turbulencecorrelation curve. The spectrathus obtained are com- ]nodelperforms a signaldecomposition into critical bandwidthchannels, paredwith the measuredones from a centrifugalblower mounted in a free specificroughness prediction for eachchannel, and a combinationof spe- field. A favorableagreement is obtainedin all testcases. 2509 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society of America 2509 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, 15 MAY 1996 REGENCY C, 8:30 TO 11:30 A.M. Session 3aPAa PhysicalAcoustics and Bioresponseto Vibration and to Ultrasound:Workshop on TherapeuticApplications of Medical Ultrasound III FrancisJ. Fry, Chair 414 WestSpring Lake Boulevard,Port Charlotte, Florida 33952 This Workshopis an attemptto bring a "small meeting"environment into a big meeting.In additionto the tutorialand special presentationsoutlined below and in therelated two sessions(2aPAa, 2pPAb); there will be significantparticipation by otherworkshop attendees;discussion among participants is a major objectiveof this program.Therefore, a specifictimetable will not be followed duringthe workshop. Chalr's Introduction---8:30 Invited Papers 3aPAal. Magneticresonance imaging guided and monitoredultrasound surgery. KullervoHynynen (Dept.of Radiol.,Brigham andWomen's Hospital and Harvard Med. School,75 FrancisSt., Boston,MA 02115) Duringthe past few yearsthere has been an interestin usingmagnetic resonance imaging (MRI) to guidefocused ultrasound beams duringnoninvasive surgery. MRI offers good soft tissuecontrast, allowing the beam to be accuratelyaimed. Temperature sensitive MRI sequencescan be usedduring low powertest pulses to visualizethe temperatureelevation in the focalzone at temperaturelevels that do not causetissue damage. This allows the beam to be aimed, eliminatingall potentialimage or ultrasoundpropagation distortions.It may evenbe possibleto calibratethe MRI signalto give the temperatureelevation and use it as a feedbackto modify the poweroutput to assureadequate thermal exposure during every therapy sonication. Finally, MRI allowstissue changes induced by the sonicationto be detected.This may be usefulafter the treatmentto establishthe boundariesof the thermaldamage and is alsovery usefulwhen experimentsare conducted.All of theseaspects of MRI guidedultrasound surgery have beeninvestigated using in vivo experimentsand the resultswill be reviewedhere. The future technicaldevelopments and potentialclinical applicationswill be discussed.[Work supported by NIH andGeneral Electric Medical Systems.] 3aPAa2.Renal injury inducedby clinicaldoses of shockwaves. AndrewP. Evan (Dept.of Anatomy,lndiana Univ., School of Medicine,635 BarnhillDr., Indianapolis,IN 46202), Lynn R. Willis, Bret A. Connors (IndianaUniv., Indianapolis,IN 46202), AnneTrout, and James E. Lingeman (MethodistHospital, Indianapolis, IN 46202) Bothclinical and experimental reports clearly show that shock wave lithotripsy (SWL) causesacute renal effects in a majority,if not all, treatedkidneys. SWL-induced acute renal damageresults in injury to the nephron,microvasculature, and surrounding interstitium.What has not been established is a setof objectivelydetermined criteria for the safeclinical use of SWL. To accomplish this goal, animalexperimentation has been conducted so that the time courseand severityof acutealterations could be followedin a modelthat closely mimics human kidney. We chosethe pig to determinethe effect (or risk)of thesize of thekidney and/or the number of treatmentsduring the samesession on the severityof the changein renalhemodynamics. Our datashows the greatestdegree of changewas induced in thekidney with the leastmass and receiving multiple treatmeres. [Work supported by NIH.] 3aPAa3. Sparse random ultrasound phasedarrays for focal surgery. Leon A. Frizzell (Bioacoust.Res. Lab., Univ. of Illinois, 405 N. Mathews,Urbana, IL 61801),Stephen A. Goss,Jeffrey T. Kouzmanoff(Labtbermics Technologies, Inc., Champaign, IL), and JosephM. Barich (Univ. of Illinois) Thefeasibility of usingnovel ultrasound phased arrays consisting of arrayelements larger than one wavelength, minimizing the numberof elementsin an aperturethrough a combinationof geometricfocusing, directire beams, and sparse, random placement of arrayelements, for tissueablution applications was examined both theoretically and experimentally. A hexagonally packed array consistingof 1088-mm-diam circular elements mounted on a sphericalshell was modeled theoretically, and a prototypearray was constructed,to examine the feasibility of sparserandom array configurations for focalsurgery. A randomlyselected subset of elements of theprototype test army (64 of 108available channels) was driven at 2. I MHz witha 64-channeldigitally controlled rf drive system. The performanceof the prototypearray was evaluated by comparingfield dataobtained from theoreticalmodeling of the array 2510 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society of Amedca 2510 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 configurationto that obtained experimentally via hydrophone scanning. The results of thatcomparison, along with total acoustic power measurements,indicate that the use of sparserandom phased arrays for focalsurgery is feasible,and that the nature of arraypacking is animportant determinant to observedperformance. [This research was supported by NationalCancer Institute Grant No. CA66462.] 3aPAa4."Popcorn"-and the role of acousticcavitation in HIFU surgery. LawrenceA. Crum (Appl.Phys. Lab., Univ. of Washington,1013 NE 40th St., Seattle,WA 98105) 3aPAa5.Fetal hemorrhagefrom lithotripterfields. DianeDalecki, Sally Z. Child,Carol H. Raeman,Christopher Cox, David Penney,and Edwin L. Carstensen(Rochester Ctr. for Biomed.Ultrasound, Univ. of Rochester,Rochester, NY 14627) Fetalhemorrhages were observed when late term pregnant female mice were exposed to a lithotripterfield with peak positive pressuresas low as I MPa. On the 18thday of gestation,the abdomensof pregnantmice were exposed to 200 pulsesfrom a piezoelectriclithotripter delivered at a rateof -- I Hz. Hemorrhagesoccurred in theexposed fetuses most often near bony and cartilagenoustissues•bead, limbs, and ribs•while softtissues such as the liver. intestine,and stomach were relatively free of hemorrhage.Thresholds for theseeffects were < I MPa. 3aPAa6.Noninvasive spatially contained high-power ultrasonic system (NSHUS). for bloodclot disintegration.Willem Grandia (QMI, CostaMesa, CA 92627),Robert J. Siegel (Cedars-SinaiMed. Ctr.,Los Angeles, CA 90048),and Yoseph Bar-Cohen (CaliforniaInst. of Technol.,Pasadena, CA 91109-8099) Ultrasonicwaves can be focusedfrom a pointoutside of thebody to an internalblood clot without using invasive techniques. Noninvasivefocused ultrasonic techniques for bloodclot disintegration may allow for prompttreatment, and eliminate the need for costlyand time-consuming invasive catheter-based interventions. Thus this noninvasive approach using therapeutic ultrasound could greatlyreduce patient mortality, morbidity, duration of hospitalization,convalescence, and cost of care.An ultrasonicsystem was designedto operatefrom 25-200 kHz andprovide a localizedhigh power. The profilesof the fieldand localization effects were analyzedto optimizepower containment to thearea of theblood clot. To demonstratesystem performance tests were initially made to dissolvesugar blocks mounted in an ice/waterbath. At thiswater freezing point, conditions of 0 øC, the rateof sugardissolution is very slow and it provideda baselineas a measureof ultrasoundeffect. Various ultrasonic frequencies and powerlevels were introducedto determinethe ultrasonicdissolution/disintegration capability. Simulated blood clots were then exposed to the localized highpower and the characteristics of the disintegration asa functionof powerand frequency were examined. The duration of exposure hasbeen a key parameterin this investigation. 3aPAa7.Therapeutic cardiac ultrasound:Ultrasound accelerated lhrombolysis, ultrasound angioplasty, and the "acoustic filter." RichardS. Meltzer (Cardiol.Unit and Ctr. for Biotaed.Ultrasound, P.O. Box 679, Univ. of RochesterMed. Ctr., Rochester, NY 14642} Ultrasoundat frequencyI MHz canaccelerate thrombolysis in an in vitrosystem using streptokinase, urokinase, or t-PA.[C. W. Franciset al., J. Clin. Invest.90 2063-2068 (1992)].Ultrasound can also hasten reperfusioo. due to thrombolyticagents both in vitro [D. Harpazet el., Am. HeartJ. 127, 1211-12190994)] andin vivoJR. Koruowskiet el., Circulation89, 339-344 (1994)].The mechanismis nonthermal,probably related to cavitation.This typeof thrombolysiswhich is associatedwith relativelow intensity, high-frequencyultrasound is to bedistinguished from the high intensity, low-frequency (- 20 kHz) ultrasoundthat has been proposed for "ultrasoundangioplasty" [A. Ernstet el., Am.I. Cardiol.73, 126-1320994)]. Potentialclinical applications and problems and limitationsto theclinical application of ultrasoundaccelerated thrombolysis and ultrasound angioplasty will be discussed.An "acous- tic filter"has been developed with the goal of removingmicrobubbles from cardiopulmonary bypass equipment, preventing neurologic damage[K. Q. Schwarzet al., I. Thorne.Cardiovasc. Surg. 104, 1647-1653(1992); US PatentNo. 5,334,136,2 August1994]. 3aPAa8.Ultrasound-mediated transdermal delivery of drugs. SamirMitragotri (Dept.Chem. Eng., MIT, Cambridge,MA02139) 3aPAa9. Damage to tissue-likestructure by wrinkled focusedshock waves. Danny D. Howard and BradfordSturtevant (GraduateAeronautical Labs., California Inst. of Techno].,Pasadena, CA 91125) Shockwaves are focusedin extracorporealshock wave litbotripsy (ESWL) machinesto strengthssufficient to fracturekidney stones.Substantial side effects--most of themacute--have resulted from thisprocedure, including injury to softtissue. The focusing of shockwaves through various layers of tissueis a complexprocess which stimulatesmany bio-mechano-cbemical responses. This paperpresents preliminary results of an in vitro studyof the initial mechanicalstimulus. Planar nitrocellulose membranes of order 10 /•m thick were usedas modelsof thin tissuestructures. Scattering media were usedto simulatethe effectsof acousticnonuniformity of tissueand to alter the structureof focusingshock waves. Hollow glassspheres of 65 ,o.mdiameter were addedto ethyleneglycol, glycerin,and castoroil to vary the properliesof the scatteringmedia. Multiple layer samplesof varioustypes of phantomtissue were testedin degassedcastor oil to gagethe validityof the scatteringmedia. The scatteringmedia and tissuesamples wrinkled the shock structurein a similar fashion.Membranes were damagedby shearstress induced by the alteredstructure: after about 20 shocks 2511 J. Acoust.Soc. Am., VoL 99, No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society of America 2511 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 immersedin thescattering media and after about 100 shocks behind the tissue samples. The modeof failurewas in shearwith multiple tearsabout 0.1 cmto about3 cmdepending on the number of shocksand membrane thickness. [Work supported by NIH GrantP01 DK43881-01A3.] 3aPAa10.Application of geometricalshock dynamics to weak shockfocusing in extracorporealshock wave litholrlpsy. .IosephE. Ca{csand B. Sturtevant(Graduate Aeronautical Labs., California inst. of Techno!.,Pasadena, CA 91125) In extracorporealshock wave lithotripsy (ESWL), weak converging shock waycs arc focused to shatterkidney stones. Accurate knowledgeof theflow field in thefocal region is requiredto understandthe source of tissuedamage and the primary mechanisms of stonefragmentation. A finite-difference numerical method for geometricalshock dynamics has been developed and used to evaluate the accuracyof thisapproximate theory for thecomplex nonlinear processes which occur in shockfocusing. The shockdynamics resultsduplicate the strong, moderate, and weak shock behaviors secn in cxperimcntsI-B. Sturtcvant and V.A. Kulkamy,JFM, 73, 651-671],with goodagreement for focalpressures and triple-point path. Similar behavior is observedfor theESWL problem of axisymmetricshock focusing in water.The primary source of erroris thefact that shock dynamics always yields Mach reflection at the centerline,so regularreficclion in the theoryis impossible.Adequate resolution of the focalregion is necessaryto assessthe accuracyof theshock dynamics theory, or of anyother theory. The shockdynamics theory and numerical method have also been extendedto themore general case of shockpropagation into a nonuniformmedia with free-stream velocity. 3aPall. Factorsinvolving precision of high-intensityfocused ultrasound treatment. Gall tcr Haar {Phys.Dept., Inst. of Cancer Res.,Suiton, Surrey, U.K.) WEDNESDAY MORNING, 15 MAY 1996 REGENCY A, 8:25 A.M. TO 12:00 NOON Session 3aPAb PhysicalAcoustics: Bob Beyer Tribute Murray S. Korman,Cochair PhysicsDepartment, U.S. Naval Academy,Annapolis, Maryland 21402 David T. Blackstock, Cochair AppliedResearch Laboratories, Universi• of Texas,P.O. Box 8029, Austin, Texas 78746-7117 Chair's Introductior•8:25 Invited Papers 8:30 3aPAbl. Robert Beyer--A profile. RobertE. Apfel {Dept.of Mech. Eng., Yale Univ., New Haven,CT 06520-8286) From 1942, when he beganhis doctoralstudies, to the presenttime, Bob Beyer hasbeen a leadingvoice in the discoveryand discernmentof acousticalphenomena, the development of educationalprograms to supportstudents in acoustics,and the dissemination of informationregarding acoustics. This introductory presentation will summarizethe "parameter space" over which Bob has modestly but impressivelyheld sway.It will includethe fieldsof acousticsto which he contributed,his careeras teacher-scholarat Brown University,his activities with theAcoustical Society of America,the American Institute of Physics,and other professional societies and organizations,and his many activitiesto aid in the internationalizationof science,in general,and acoustics,in particular. 8:40 3aPAb2. Acousticsat Brown University: 1956-1958. G. Maidanik (David Taylor Model Basin, NSWC, Bethesda,MD 20O84-5000) In earlierand in thoseyears the physics department at BrownUniversity was mostly acoustics: Profs. B. Lindsay,A. O. Williams, R. Beyer, P. Westervelt,W. Nyborg, R. Morse, and otherswere all major acousticiansin thosedays, in fact, I convertedfrom low-energyphysics to acousticsunder their guidance. The newsof conversionwas drowned, however, by thenoise that Sputnik generatedin 1957.While the physics and engineering departments were engaged in noisecontrol activities in thepopulace at large, Prof.Beyer characteristically turned his energiesto upgradinghigh schools' proficiency in physics.In a few months,a "summer teachingfor the teachers"was organized at BrownUniversity and a dozenyears later we did get to the moon. 2512 J. Acoust.Soc. Am., Vol.99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2512 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 8:50 3aPAb3. Robert T. Beyer from his students'perspective. Mark B. Moffett (Naval UnderseaWarfare Clr., New London,CT 06320)and Stephen V. Letchef (Univ.Rhode Island, Kingston, RI 02881) ProfessorRobert T. Beyerguided 20 Ph.D. studentsand 9 Sc.M. studentsduring his career at BrownUniversity. He did a masterful job of preparinghis studentsfor successfulcareers in teachingand research. His genial,outgoing personality ensured good commu- nicationwith eventhe introvertsamong them and his relaxed style (and the close quarters during the Wilson Hall days)encouraged interactionsamong the students;they oftenlearned the tricksof the ultrasonicstrade from each other. Hc kept a closewatch, however, andwhen he delerminedthat a studentwas ready to presenthis first paper at an AcouslicalSociely meeting (often before the student consideredhimself ready), he stronglyencouraged it and instilledthe confidenceneeded for the task. He personallyintroduced his studentsto manyof the Society'smembers, resulting in lifelongfriendships and collaborations. Although none of BobBeyer's students ever succeededin emulatinghis ability to tell a storyor a joke, they all have benefitedgreatly from their associationwith him. 9:05 3aPAb4.Robert T. Beyer'scontributions in ultrasorties. StephenV. Letchef (Univ. RhodeIsland, Kingston, RI 02881) RobertT. Beyer was a majorcontributor to our understandingof ultrasonicrelaxation processes in liquidsand solidsduring the heydayof thatfield. One could argue that this period ran roughly from the time of hismajor review article in 1951[.L .L Markham, R. T. Beyer,and R. B. Lindsay,Rev. Mod. Phys. 23, 353-411 0951)] untilhis monograph in 1969JR. T. Beyerand S. V. Letchef, PhysicalUltrasonics (Academic, New York,1969)]. He adoptedand extended new measurement techniques of ultrasonicattenuation and usedthem to advanceour understandingof relaxationprocesses in liquifiedgases, in waterand aqueoussolutions, in organic liquidsand organic single cryslals. and in liquidmetals. 9:20 3aPAb5.Bob Beyer'snontechnical contributions to acoustics.M. Strasberg(David Taylor Model Basin,NSWC, Bethesda,MD 20084-5000) A review of Bob's contributionsto the goalsof our Society,including his servicesto the AcousticalSociety of America,the American Instituteof Physics,the InternationalCommission on Acoustics,and translationjournals. interspersedwith anecdotes highlightinghis remarkableerudition, talents, and humor. 9:35 3aPAb6.Robert T. Beyer'sinteraction with foreignacoustical scientists. KonstantinNaugolnykh (CIRES, Univ. of Colorado/ NOAA/Envi Technol.Lab., Boulder,CO 80303) The very essenceof a scientificsociety is the promotionof cooperationand the exchange of informationamong scientists. Bob's contributionto acousticsin thisfield is twofold.First, he is deeplyinvolved in thepublication of acousticsliterature, particularly the RussianAcoustical Journal (previously Soviet Physics--Acoustics, now Acoustical Physics). Perfect knowledge of the languages,a deepinterest in the creativework, a wide rangeof interests,and an extensiveoutlook help him in this activity.Second, being openheartedand having a friendlynature, with a live interestin his colleagues,he doesa lot to developscientific links and contacts. When he visitedUSSR in 1958, he immediatelyswitched on acousticalcommunity activity, participated in the Ph.D. thesisdefense of Lev Zarembo,and started a long-livedcooperation with Russiancolleagues. He haseducated Ph.D. andpostdoctoral students from China,Norway, Russia, etc. All of them are gratefulto Bob and keepa lot of goodrecollections. Each meetingwith him leavesyou with a feelingof cordialwarmth and friendlyconcern. 9:45 3aPAb7.Robert T. Beyer'simpact on the developmentof nonlinearacoustics. PeterJ. Westervelt (Dept. of Phys.,Brown Univ., Box 1843, Providence,RI 02912} If it hadnot beenfor R. T. Beyerthere would not havebeen papers by me and my studentsfor JASA to reject.Why is this?He (andA. O. Williams)wrote most of my contractproposals and the associated progress reports. He andhis students Stanton, Bellin, and Kormanperformed definitive experiments supportive of my muchcriticized theories. In this tributeto Beyer I will discussthese experimentsand touchupon my interactionwith GoneFubini. 10:00 3aPAb8.R. T. Beyer'scontributions to nonlinearacoustics. David T. Blackstock(Appl. Res. Labs., Univ. of Texas,Austin, TX 78713-8029and Mech. Eng. Dept., Univ. of Texas,Austin, TX 78712-1063) Exceptfor a reviewarticle on radiation pressure [Am..L Phys. (1950}], Robert T. Beyer'searliest research in nonlinearacoustics wason the increaseof absorptionwith intensityfor waterand other liquids [J. Acoust.Soc. Am. (1956}(1957}, and Soy. Phys.- Acoustics{1958)]. New directionssoon followed: the experimental work on theparametric array [Bclli et al., J. Acoust.Soc. Am. (1960)(A)], theKeck-Beyer perturbation solution for finite-amplitude waves in a viscousliquid [Phys. Fluids (1960)], and calculation of the parameterof nonlinearityBIA [J. Aeoust.Soc. Am. (1960)].Continuation and expansion of the latterwork madeBob the foremostauthority on BIA. Laterinterests include nonlinear effects in thefield of a pistonradiator [Ryan et al., J.Acoust. Soc. Am. (1962)],finite-amplitude propagation in a relaxingfluid, self-demodulation of a pulse[Moffett eta/., J. Acoust.Soc. Am. (1970, 1971)], andvarious aspects of thecrossed beams problem [J. Acoust. Soc. Am. (1970-1982)].To thesespecific contributions must be addedBeyer's book Nonlinear Acoustics and severalreview articlesin handbooksand journals. 2513 J. Acoust.Soc. Am., VoL99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2513 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 3aPAb9. Bayer on Bayer. Robert T. Bayer (Phys.Dept., Brown Univ., Providence, RI 02912) Reflections. 10:30-10:45 Break ContributedPapers 10:45 nentsof B/A will be comparedwith experimentaldata for a seriesof normalalkane liquids. A comparisonof theseresults with theprediction of 3aPAb10. Recollectionsof acousticsat Brown University in the early Ballou'srole 0inearrelation of B/A vs llc) will be presented.Tentative fifties. S.A. Elder (Phys.Dept., US Naval Aced., Annapolis, MD 21402) conclusionsabout the relative utility of thetwo equationswill be presented When I arrivedat Brown in 1950,Bob Bayer,a youngassistant pro- as well as the outlookfor the approachusing any PVT equationof state. fessor,was already becoming well knownas an acoustician.Within a year [Work supportedby Naval SurfaceWarfare Center's in-house Laboratory he waspromoted to associateprofessor and took over the "References" IndependentResearch Program sponsored by the Office of Naval Re- sectionof JASA at the deathof Arthur TaborJones. Having previously search.] translatedworks in German,soon he had taughthimself Russian and be- come known as the editor of JETP, the Russiantranslation journal. I took an ultrasonics course from him, about the time the milestone article on acousticabsorption by Markham,Bayer, and Lindsay came out in Reviews of Modem Physics.In thosedays Brown Physicswas a powerhouseof 11:30 expertisein acoustics,with threeout of everyfour facultymembers spe- 3aPAb13. Nonlinear acoustic Doppler effect in a bubble flow. Igor cializingin that field. In 1952 distinguishedacousticians from aroundthe N. Didenknlov (Inst. of Appl. Phys.,46 Ulyanov Str., Nizhny Novgorod worldgathered at Brownfor an ONR ultrasortiessymposium. As the field 603600, Russia),Suk-Wang Yoon, Eui-Jun Kim (Dept. of Phys.,Sung of nonlinearacoustics began to evolve,Bayer, along with Lindsay,Nyborg, Kyun Kwan Univ., Suwon,440-746, Republic of Korea),and Alexander Wasteryah,and theirstudents, was busyexploring high amplitudeeffects M. Sutin (Inst. of Appl. Phys.,46 Ulyanov Str., Nizhny Novgorod suchas anomalousabsorption, acoustic streaming, and, later, scattering of 603600, Russia) soundby sound.All thistook place in an ancientrelic of a buildingcalled WilsonHall, with an atticfull of dustyapparatus left from a departed19th The Dopplereffect is a well-knownand widely usedphenomenon. In centurydepartment chairman, and a basementfull of great,mosquito- acousticsit is usuallyconsidered for linearresponse from a movingtaxget. infested ultrasonic water tanks. No attentionwas given previouslyto specificphenomena of nonlinear soundscattering by movingnonlinear scatterers. In the presentpaper a 11:00 nonlinearanalog of the Doppler effect is studiedtheoretically and experi- mentally.The most prominentnonlinear acoustic scatterer is a bubble.A 3aPAbll. Vintage Bayer--Teacher, advisor, and mentor---an era of theoreticalanalysis of frequencyshift undernonlineax scattering of two, in experimentation on the nonlinear interactions of sound with noise a generalcase, acoustic waves by a movingnonlinear scatterer with gen- and with turbulence. MurrayS. Korman (Dept.of Physics,US Naval eration of harmonicsand combination(i.e., the sum and the difference} Academy,Annapolis, MD 21402) andTimothy K. Stanton (WoodsHole frequenciesis given.It is shownthat the nonlinearDoppler frequency shift OceanographicInst., Woods Hole, MA 02543) for the differencefrequency generation depends on the geometryof pri- marywaves and can be muchlarger than the linearDoppler frequency shift When ProfessorBayer taughtus ultrasonicsor nonlinearacoustics at for the differencefrequency. Experiments have been made with bubble Brown, he emphasizedthe historicalgenesis of scientificideas and in- flows in a vessel.The resultsare in good agreementwith the theory. eludedinsight into the worksof greatslike Rayleighand connectionsto Feasibleapplications of the nonlinearDoppler efl•:ctfor bubbleflow ve- Lighthill.He personalizedthe science.His lectureson "RadiationPressure locitymeasurement are discussed and demonstrated experimentally. [This -- The Historyof a MislabeledTensor" [J. Acoust.Sec. Am. 63, 1025- work was doneat the AcousticResearch Lab. of Sung Kyun Kwan Univ. 1030 (1978)] are vintageBayer. If our researchtopics were a canvashe under supportof STEPI, Republic of Korea, and supportedin part by would motivatethe developrnentof our creativity.If you askedhim which RFBR (grant94-05-16755), Russia.] colorto use,you wouldget a philosophicalstory--but not whichcolor. He providedguidance but the final brushstrokes were yours.TKS and RTB's "interactionof soundwith noise"0978) featuredthe growthof sumand differencefrequency sidebands that agreed with Wasterreit. MSK and RTB's "scatteringof crossedultrasonic beams in the presenceof turbu- 11:45 lence"(1988) measuredturbulent velocities. Some of Beyer'sdaily com- mentsstill ring throughour minds"Don't just standthere -- go write a 3aPAb14. Nonlinear acoustic method for bubble density thesis,"or "oncea graduatestudent -- alwaysa graduatestudent." How- measurements.Alexander M. Sutin (Inst.of Appl. Phys.,46 Ulyanov ever, at key talks. like our thesisdefense his "When you are on the goal Str., Nizhny Novgorod603600, Russia),Suk-Wang Yoon, Eui-Jun Kim line shootstraight up the middleand do not attempta long forwardpass," (Dept.of Phys.,Sung Kyun Kwan Univ., Suwon, 440-746, Republic of will always echo in our minds. Korea'S,and Igor N. Didenkulov (Inst.of Appl. Phys.,46 LilyahoyStr., Nizhny Novgorod603600, Russia} 11:15 An enormouslyhigh nonlinearresponse of a bubble to an acoustic 3aPAb12. Beyer's B/A parameter and the equation of state. Bruce excitationmakes nonlinear methods possible and very selectivefor bubble Hartmann,Gilbert F. Lea, and Edward Balizer (Naval SurfaceWarfare observationand sizing.Among differentnonlinear acoustics methods of Ctr., Silver Spring,MD 20903) bubbledetection there is one basedon differencefrequency generation underthe actionof two high- frequencypump waves. In this methodthe Beyer'sB/A parameterfor liquidscan be calculatedusing an analytical nonlinearscattering from a singlebubble was studied. In thepresent paper PVT equationof statesupplemented with specificheat data. Resultsfor the nonlinearincoherent scattering of two high-frequencyacoustic waves two equationswill be investigated:the Tait equationand our own. The with the differencefrequency generation from a bubblecloud was theo- calculationsof soundspeed, sound speed derivatives, and the two compo- reticallyand experimentally investigated to estimatebubble size distribu- 2514 J. Acoust.Soc. Am., Vol. 99, No.4, Pt.2, April1996 131stMeeting: Acoustical Society of America 2514 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 tipns.In theexperiments two primarywaves were produced by focused electrolysis-and slit-type bubble makers, the bubble densities were well transducers.One of the primaryfrequencies was keptconstant at 2.25 estimatedwith the present nonlinear acoustic method, respectively. [This MHz; anotherwas changed.Thus the differencefrequency was varied work was doneat the AcousticResearch Lab. of SungKyun Kwan Univ. from30 to 320 kHz, whichcorresponds to the resonant bubble radii from undersupport of STEPI,Republic of Korea,and supported, in part,by 109to 10 /.• m. For the bubbleclouds produced in a laboratorytank by RFBR(Grant 94-05-16755), Russia.] WEDNESDAY MORNING, 15 MAY 1996 REGENCY B, 8:00 A.M. TO 12:00 NOON Session 3aPP Psychologicaland Physiological Acoustics: Binaural Hearing and Hearing Impairment FredericL. Wightman,Cochair WatsmanCenter, University of Wisconsin,1500 Highland Avenue, Madison, Wisconsin 53706 MarjorieR. Leek,Cochair Audiologyand Speech Center, Walter Reed Army Medical Center, Washington, DC 20307-5001 ContributedPapers 8:00 IDT was 0, 50, 100, or 200 /xs. Here, targetweights and percentcorrect generallyincreased for all listenersas the mean distractor IDT increased. 3aPPl. Effectsof sourcespectrum irregularity and uncertaintyon Resultsare attributed to increasedtarget weight as thedifference between sound localization. Ewan A. Macpherson(Watsman Ctr., Univ. of targetand distractor IDT increased,and decreased sensitivity to changesin Wisconsin--Madison,1500 Highland Ave., Madison, WI 53705-2280) IDT as meanIDT increased.[Work supportedby a ProgramProject Grant Localizationperformance has been shown to deterioratewhen source from NIDCD.] spectraare variable, but the few studies investigating this have confounded trial-to-trialvariability with spectralirregularity present in eachstimulus. 8:30 In thisexperiment these factors were varied independently. Blindfolded listenersseated in an anechoicchamber reported the apparentlocations of 3aPP3.Dichotic pitches as illusionsof binauralunmasking. John F. widebandnoise bursts having either smoothly sloping spectra or l/3-oct Culling (Univ.Lab. of Physiol.,Parks Rd., OxfordOXI 3PT,UK), scrambledspectra. The spectra were either varied from trial to trialor held QuentinSummerfield (M.R.C. Inst.of HearingRes., University Park, constantthroughout an experimentalsession. Localization performance NottinghamNG7 2RD,UK), andDavid. H. Marshall(M.R.C. Inst. of wascompared to thatobtained in a baselinecondition using fiat-spectrum HearingRes., University Park, Nottingham NG7 2RD,UK) stimuli.Despite trial-to-trial uncertainty, performance with the smoothly varyingspectra was equivalent to baseline.The responses to the majority Dichoticpitches are binaural perceptual phenomena which occur when of thescrambled spectrum stimuli were similar to baseline,but pronounced broadbandnoise with specificinteraural phase/time relationships is pre- biasand elevatedvariability were observedat certainpairings of source sentedsimultaneously to the two ears.Four dichoticpitches have been spectrumand location that varied between listeners. The degree of uncer- described:Huggins' pitch; the binaural edge pitch; the Fourcin pitch; the taintyhad no substantialeffect on performancewith thesestimuli. The dichoticrepetition pitch (DRP). This paper shows that the perceived pitch resultssuggest that source spectrum familiarity cannot effectively compen- andtimbre of the firstthree dichotic pitches are correctly predicted using satefor the interferenceof spectralirregularity with the processingof a modelof binauralunmasking [Culling and Summerfield, J. Acoust.Soc. spectrallocalization cues. However, this processing appears to besurpris- Am. 98, 785-797 (1995)].The modeldetects across-frequency variations inglyimmune to suchinterference over much of auditoryspace. [Work in interauralcorrelation; the resulting central spectrum shows peaks which supportedby NIDCD.] correspondto the frequencies listeners hear. These pitches are probably, therefore,illusions produced by the mechanismof binauralunmasking. The DRP is notpredicted by themodel. The DRPcould be produced 8:15 throughbinaural cross talk, but experiments using insert earphones which produceminimal cross-lalk confirmed that the phenomenon persists when 3aPP2. Observerweighting of interaural differencesof time in crosstalk is effectivelyeliminated. The DRP is probably,therefore, pro- differentregions of intracranialspace. Mark A. Stellmack(Watsman ducedby a separatemechanism from the other dichotic pitches. Ctr., Univ. of Wisconsin--Madison,1500 HighlandAve., Madison,WI 53705)and RaymondH. Dye, Jr. (ParmlyHearing Inst., Chicago, IL 60626) 8:45 Weightsthat listeners placed on interaural differences of time (IDT's) 3aPP4. Binaural detectionwith spectrallynonoverlapping signals werecomputed for two pure tones that had different mean IDT's. As a cue andmaskers. Marcel van der Heijden, Constantine Trahiotis [Surgical on eachtrial, thetarget (753 Hz) waspresented in isolationat its mean ResearchCtr., Dept. of Surgery(Otolaryngol.) and Ctr. for Neurol. IDT. Then,the targetand distractor (553 Hz) werepresented simulta- Sciences,Univ. of ConnecticutHealth Ctr., Farmington,CT 06030], neouslywith IDT's selected from Gaussian distributions (o-= 50kts). The Armin Kohlrausch,and Stevenvan de Par (Inst. for PerceptionRes., listenerindicated whether the targetin the test intervalappeared to have NL-5600 MB Eindhoven,The Netherlands) movedto the left or right of its cuedposition. The weightswere the correlationsbetween the IDT of eachcomponent and the listener'sleft/ Thresholdswere measuredfor diptic tonal signalsmasked by interau- rightresponse. In one condition, the mean target and distractor IDT's were rallydelayed bands of Gaussiannoise. When the signal frequency was 525 of equalmagnitude (0, 25, 50, 100,and 200/xs) but opposite sign. Large Hz, thespectrum of themasker was either below (highest frequency, 450 individualdifferences in weightsand percent correct were observed. In a Hz) or above(lowest frequency, 600 Hz) thefrequency of thesignal. With secondcondition, the mean target IDT was0 /xs andthe mean distractor a 450-Hzsignal, the spectrum of themasker was always above the signal 2515 J.Acoust. Soc. Am., Vol. 99, No. 4, Pt.2, April1996 131stMeeting: Acoustical Society ofAmerica 2515 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 frequency(lowest frequency, 600 Hz). Signalshad a 250-msduration and 9:30 weretemporally centered within 300-m•-long maskers. The spectrumlevel 3aPP7. Detection and identification of environmental sounds, of the maskers was 60 dB. Masked thresholds obtained in all three condi- tions variedsinusoidally with the interauraldelay of the masker.The pe- CharlesS. Watson,Gary R. Kidd, and BrianGygi (Dept. of Speechand riodicitieswithin the data were closeto, but not identicalwith, the peri- Hear. Sciences,Indiana Univ., Bloomington,IN 47405) oclicitiesof the signals(not the maskers).This outcomeis discussedin Moststudies of auditoryrecognition and identification have employed termsof (1) auditorydistortion products stermning from interactions eitherspeech stimuli or nonspeechsounds generated in thelaboratory (e.g., withinthe masking hands of noise[cf. vander Heijden and Kohfrausch, J. Ionesof variousfrequencies, tonal patterns, click trains). The presentstudy Acoust.Soe. Am. 98, 3125-3134 (1995)],and (2) binauralmodels incor- employed25 naturallyoccurring complex sounds (obtained from a com- poratinginternal delay mechanisms. It is shownthat using such spectrally mercialsound-effects library), such as thoseproduced by doorsclosing, nonoverlappingsignals and maskerscan help test interestinghypotheses babiescrying, helicoptersin flight, and other familiar events.These concerningbinaural models. [Work supportedby Grant No. 5 ROI sounds,equated for peak levels,were recordedwith a backgroundof DC00234-13 from the National Institute of Deafness and other Commu- broadbandnoise. The recordedsounds were presentedto groupsof six to nicationDisorders, NIH.] eight listenersin both open- and closed-setformats (with the list of re- sponsesdisplayed continuously in the latter). Confusionmatrices were generatedusing a widerange of event-to-noise(Ev/N) ratios.Two frequent 9:00 confusions were identified for each item, and were used to create a three- alternativeforced choice test. F.ight values of Ev/N were selectedfor each 3aPP5. Lateral position of dichotic pitches can be substantially item in an effort to achieveuniform item identifiability.Average Ev/N affected by interaural intensitive differences. Anthony N. Grange and ConstantineTrahiotis (Surgical Res. Ctr., Dept. of Surgery requiredto achieve50-percent-correct recognition, the slopesof psycho- (Otolaryngol.)and Ctr. for Neuro1.Sciences, Univ. Ctr. of Connecticut metricfunctions, and the distributionof thesemeasures among nor'real- hearinglisteners are comparedto the correspondingmeasures for speech HealthCtr., Farmington,CT 06030} identification.[Work supported by AFOSR andNIDCD.] Three listenersused an acousticpointer to matchthe intracranialpo- sitionof dichoficpitches presented with interauralintensitive differences (liDs). Unlike datareported previously [Raatgever, "Binaural time pro- cessingand time-intensitytrading," in Psychophysics,Physiolog3: and BehaviouralStudies in Hearing, edited by G. van den Brink and F. A. 9:45 Bilsen(Delft U.P., Delft, The Netherlands,1980), pp. 425-453], the in- 3aPP8. Perceptualfusion of multiple echoes. SandraJ. Guzmanand tracranialposition of the dichoticimage was movedsubstantially by IIDs. WilliamA. Yost (ParrelyHear. Inst., Loyola Univ., 6525 N. SheridanRd., Largeeffects of lids were foundin a valery of stimulusconditions, in- Chicago,IL 60626) cludingone investigated by Raatgever.When the dichoticstimuli were not pulsed,but were presentedcontinuously and turnedoff only when the In a naturalenvironment, perceptual fusion of a soundmay occur acousticpointer was presented,one of the listenersproduced data like despitethe fact thatmultiple echoes exist. If a trainof repeatingsources thosepreviously reported by Raatgever.It appearsthat intracranial images and echoesis establishedexperimentally, the echoesare suppressedand producedby stimuliwhich support dichotic pitches, like imagesproduced perceptualfusion is established.lu thepresent study, perceptual fusion was by other binauralstimuli, can be affectedsubstantially by lids. Conse- investigatedby havinglisteners attend to the l•st soundpresented in a train quently,in termsof iateralization,it doesnot appearnecessary to maintain of sourcesand echoes.The effectsof the numberof soundspresented a theoreticalcleavage between images produced by dichoticpitches (pre- duringa train,time delaybetween sources and echoes, relative amplitude viouslythought to be influencedonly by 1TDs) and imagesproduced by betweensources and echoes,and numberof echoespresented were inves- otherbinaural stimuli. [Work supported by GrantNo. 5 ROl DC00234-13 tigated.Results indicate that there is an interactionbetween time delay and from the National Institute on Deafness and other Communication Disor- numberof echoesin perceptualfusion. Relative amplitude of the source ders,NIH.] and echoesalso affectedperceptual fusion. These findingswill be dis- cussedin termsof theconditions under which perceptual fusion seems to occurand its relationto a listener'sprior experience in an acousticenvi- 9:15 ronment.[Work supported by NIDCD andAFOSR.] 3aPP6. Localizationand speech perceptionin no•se by aging listeners. RobertC. Bilger (Dept. Speechand HearingSci., Univ. of 10:00-10:15 Break Illinois,901 S. SixthSt., Champaign,IL 61820), ChienYeh Hsu (Inst.for InformationIndustry, Taipei, Taiwan, Republicof China) and Ted A. Meyer (WashingtonUniv., St. Louis,MO 63110) Presbycusiclisteners are reported to havedifficulty hearing speech in 10:15 noisysound fields. To resolvethe issueof whetherthis difficulty is central 3aPP9. Fransseneffect as a function of carrier waveform, carrier or peripheral,an experiment,in whichthe spectrumof a maskingnoise level, and room acoustics.Dan Mapes-Riordan,William A. Yost,and wasmanipulated to replaceacoustics that a listener'speripheral hearing SandraJ. Guzman (ParmlyHearing Inst., Loyola Univ., 6525 N. Sheridan lossfiltered out of the input,was conducted. The experimentallisteners Rd., Chicago,IL 60626) were12 people with high-frequency hearing loss who were 65 yearsof age or older (5 women/7men) and the controlswere 12 youngadults with The Fransseneffect was studied as a functionof the frequencyof the normalhearing (8 women/4men). When PB words(200 words/condition) sourceand echo sounds, the difference in frequencyand levelbetween the were presentedat 65 dB SPL in a flat noise(S/N = 0 dB) at zero azimuth, source and echo sounds, and as a function of the amount of room rever- the controlsscored 53.9% correctand, when the speechand noisewere beration.A modificationof thesingle-interval procedure used by Hartmann separatedby 90 ø, their score was 70.2% correct, an increase of 16.3% and Rakerd[J. Acoust.Soc. Am. 86, 1366-1373 (1989)] was usedto Underthe sameexperimental conditions, the experimentallisteners scored measure the degree to which the source and echo soundswere fused in 44.8% correctfor signaland noiseat zero azimuthand 53.4% correctfor termsof determiningthe locationof the perceivedsound. The amountof 90ø separation,an increaseof only8.6% When the noise presented to the fusionwas a nonmonotonicfunction of frequency,decreased as the fre- experimentallisteners was filtered to matchtheir equal-loudness contours quencyand level difference between the echo and source increased, and is (high-frequencyboos0, however, their speech recognition improved to greaterfor a room with more reverberation.The resultswill be discussed 59.5%,an increaseof 14.7%over their mean score for no separationof in termsof theprecedence effect, listener's prior experience, and the plau- signalfrom noise, evidence that their difficulty is of peripheralorigin. sibilityhypothesis. [Work supported by a ProgramProject Grant from [Worksupported by DC 00174-11.] NIDCD anda grantfrom the AFOSR.] 2516 d.Acoust. Sec. Am., Vol. 99, No. 4, Pt.2, April 1996 131stMeeting: Acoustical Society ofAmerica 2516 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 device.!n impairedlisteners, performance in quietwas significantlybetter with theears unoccluded or fittedwith the E-A-R HI-F[ plugsthan with the 3aPPI0. Target weights for high-frequency SAM targets and otherconventional devices. ANR wasmidway. In noise,performance was distractorslateralized on the basis of envelopedelay. R. H. Dye relativelybest with ANR and worst with the ears unoccluded.Within (Parmly Hear. Inst., Loyola Univ., 6525 N. SheridanRd.. Chicago,IL group,there were no differencesin eitherduration of frequencydifference 606261 limens, acrossconditions. Protected frequency DLs were significantly The extentto whichjudgments of the lateraltryof SAM high-frequency greaterfor the impairedgroup. The resultssupport considering both hear- carriersis influencedby other SAM toneswas assessedin a stimulus- ing statusand task in asscssinghearing protectors. [Work supported by classificationparadigm. The targetwas either a 4- or a 2-kHz tone modu- NationalDefence Canada.] lated at 200 Hz, and the distractor was a 2- or 4-kHz tone modulated at ratesranging from 50 to 400 Hz. Of particularinterest is the mannerin which the weight given to the target is dependentupon the carrier and 11:15 modulationfrequencies. On eachtrial, the targetwas presented with oneof ten envelopedelays, as wasthe distractor.Each test intervalwas preceded 3aPPI3. Differencesin modelingadaptation for the hard of hearing by a dioticpresentation of the targetalone. The relativecontributions of the versus normal listeners. Hong-Wei Dou, Ion Mackay. Maureen envelopedelays of the targetand the distractorwere assessedby the point- Korman.Teri Huber, MarianneMartin, HeatherBose, StephanieHall, biserialcorrelations between the target/distractordelays and the type of Dana Homan. Gena Walls. Dana Hawes, David Sandman, and Ernest M. responseelicited ("left"/"right"). Althoughsubstantial individual differ- Weiler (CommunicationSciences and Disord., Univ. of Cincinnati, ML enceswere found in terms of which carrier was more potentand in how No. 379, Cincinnati, OH 45221) targetweight dependedupon modulationfrequency, the relationshipbe- Data gatheredby Kormanand Weiler [MA thesis,Univ. of Cincinnati, tweentarget weight and modulationfrequency tended to be the samefor 1986]and Janson et al. [Br. J. Audiol.30, 35-42 (1996)] haveshown the the two carrierfrequencies for a given listener. loudnessfunction for loudnessadaptation gathered by the ipsilateralcom- parisonprocedure (ICP) diffi:rsfor normalhearing listeners and those with 10:45 high-frequencycochlear loss. This paperinvestigates the modelingas- sumptionsfor loudnessgrowth in the two kindsof listeners.Surprisingly, 3aPPII. Phasediscrimination and stimuluslevel in normal-hearing the loudnessgrowth within a given frequencyis not clearly diffi:rentin and hearing-impairedlisteners. Marjorie R. Leek (Army Audiol. & kind, althoughthe two groupsstart with different values in most test Speech Ctr., Walter Reed Army Medical Ctr., Washington, DC conditions.However, there does appear to be a differenceacross frequen- 20307-5001),Roy D. Patterson(MRC Appl. Psych.Unit, Cambridge cieswhich may be a reflectionof the spreadof excitationon the basilar CB2 2EF, UK), and Van Summers (Walter Reed Army Medical Ctr., membrane.Expected differences in activationfor normal listenersand Washington,DC 20307-5001) thosewith a high-frequencyloss will be discussed. In a linear filterbankthere is a simpletrade-off between filter band- width and durationof the impulseresponse. This suggeststhat hearing- impairedlisteners with broad auditory filters will have abnormallyacute 11:30 temporalsensitivity. and wouldbe more sensitivethan normalto phase 3aPP!4. Multimlcrophone directional hearing aid using hybrid manipulationsin harmonicstimuli. However. repeated attempts to substan- adaptive beamforming. G. L. Gibian W. S. Koroljow (Planning tiate this predictionhave largely failed. Linear modelsfail to accountfor Systems.Inc., 7923 JonesBranch Dr.. McLean,VA 22102) the loss of gain associatedwith outer haircell damagein the impaired cochlea.In preparationfor modelingphase discrimination with an active Recenl studieshave demonstratedsome successin improvingspeech cochleamodel, phase discrimination thresholds were measuredat a num- intelligibilitywhen either competingvoices or reverberationare present, ber of stimuluslevels for normal-hearingand hearing-impairedlisteners in usingan adaptivebeamformer in the firstcase and a fixed-weightbeam- a standard/2AFCexperiment. Stimuli were 21-componentharmonic com- former in the second.The presentstudy evaluates the effectivenessof a plexeswith a fundamentalfrequency of 125 Hz. The standardhad all hybridbeamformer incorporating the strengthsof an adaptivebeamformer componentsin cosinephase. Test stimuli had odd-numberedharmonics in with the advantagesof an optimallychosen fixed-weight beamformer. Re- cosine phase and even-numberedharmonics shifted a fixed number of ceivedsignals at a shortarray of micropbonesin a roomwere simulated for degreesas determinedby an adaptivetrack. For both groupsof listeners, a single talker and for a babbleof voicesat each of severalinterferer phasediscrimination deteriorated as stimulus level decreased below 30-40 locations.Three roomswith differentabsorption coefficients were simu- dB SL. The importanceof sensationlevel to theseresults and their lack of lated. Conditions with more than one simultaneous interferer location and dependenceon frequencyresolution will be discussedin termsof linear with startsand stops of an interreferare being tested. Success of thehybrid and level-dependentmodels of cochlearfunction. [Work supportedby adaptivebeamformer is beingassessed by informallistening and by mea- suringthe intelligibility-weightedimprovement in SNR• Preliminaryre- sultsappear promising. I1:00 3aPPI2. A comparisonof Ihe effectsof active noise reductionand 11:45 convert!tonal hearing protectors on auditory perception in normal and bearing-impaired listeners. Sharon M. Abel and Deborah L. 3aPPI5. Predicting custom hearing aid circuit selectionsuccess from Spencer (Dept. of Otolaryngol.,Mount Sinai Hospital,600 University field returns analysis. David A. Prevesand Mary E. Leisses (Argosy Ave., Toronto, ON MSG IX5, Canada) Electronics, 10300 W. 70th St., Eden Prairie, MN 55344) The relativebenefit of active noisereduction (ANR), comparedwith A wide varietyof signalprocessing circuitry is availablefrom hearing conventionalhearing protection, was assessed.Two groupsof normal- aid manufacturersfor use in customhearing aids. Whetherthe type of hearingsubjects, differing in age,and one group with bilateral sensorineu- circuitused is specifiedby theclinicion or by the manufacturer,the selec- ral hearingloss participated.Subjects were testedwith the ears unoc- tionprocess is oftenspeculative because of thelack of understandingabout eluded, and fitted with E-A-R foam plugs, E-A-R HI-F1 plugs, Bilsom how diffi:renttyp•s of signalprocegsing interact with pathologicalauditory Viking muffs,and Peltor7004 muffs with ANR capability.The E-A-R systems.An empiricalapproach to signalprocessing selection is proposed foam plug providedthe highest,and the E-A-R HI-F1 plug the lowest, basedon the circuit that is most likely to minimize field returnsfor a real-world sound attenuation. from 250 Hz to 8 kHz. The Bilsom and particularaudiometric configuration, degree of loss, and hearingaid Peltor muffs were midway and virtually identical.ANR reducedsound model.Several thousand ITE and ITC hearingaid fillings madeby one levelsby an additional10 dB at 250 Hz. In normallisteners, protectors hearingaid manufacturerwere monitored via a computerizedfield tracking improvedword recognition in noisebut there was no difference due to the database for incidenceof repairsand returns for credit.Circuits included 2517 J. Acoust.Soc. Am., Vol.99, No. 4, Pt. 2, April1996 131st Meeting:Acoustical Society of America 2517 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 four typesof signalprocessing having class D outputstage: linear, input IDIS artificial intelligenceprogram, and designrules were formulatedto compression,TILL, and BILL. Audiogramswere dividedinto sevencon- maximizefitting success. From these rules, signal processing type(s) were figurations:flat, gradually sloping, steeply sloping, precipitous,rising, identifiedfor each audiometricconfiguration that would minimize field cookie bite, and inverted cookie bite. The database was entered into the returns. WEDNESDAY MORNING, 15 MAY 1996 CANYON HALL, 8:00 TO 10:30 A.M. Session 3aSAa Structural Acoustics and Vibration: Plates, Beams, and Shells Sabih I. Hayek, Coehair Departmentof EngineeringMechanics, Pennsylvania State University,227 HammondBuilding, UniversityPark, Pennsylvania16802 John A. Burkhardt, Cochair Departmentof Engineering,Indiana-Purdue Universit), at Ft. Wayne,2 I01 East ColiseumBoulevard, Ft. Wayne,Indiana 46805-1499 ContributedPapers respectto the longitudinal(CL) and shear (cr) velocitiesof the plateand to the longitudinalvelocity of the fluid (CF} are studied.The plot of the 3aSAal. Application of matched-field processing to structural previousderivatives, versus the frequency,exhibits Brett-WiSher peaks. vibration problems. GabriellaTurek (Marine PhysicalLab., Scripps Theirhalf-widths are equal to F* andthe coefficients FL, F r , F F related Inst.of Oceanogr.,8603 B La JollaShores Dr., La Jolla,CA 92093-0238) to their amplitudeare introduced.The physicalmeaning of the p•evious and W. A. Kuperman (ScrippsInst. of Oceanogr.,San Diego, CA amplitudecoefficient is given.Then a resonantenergy conservation law is 92093-0701) shown:F*+FF=FL+FT. Theapplicability of matched-fieldprocessing (MFP) [Baggeroer et aL, IEEE J. Ocean.Eng. 18, 401-424 (1993)]techniques to localizesources of 8:•0 vibrationin structuresand to performnondestructive testing is explored. MFP is a generalizedprocedure of array processingused in oceanacous- 3aSAa•. Waves and vibrations in multilayer poroclasticplates. M. tics to either localize sourcesor perform inversions.MFP involvescorre- CengizD•ikmeci (Istanbul Tech. Univ.-Teknik 0niv. P.K.9, Taksim, lationsbetween the solutions(or "replicas")of the wave equationfor a 80191 Istanbul,Turkey) and 13.Askar Altay (Bo•azi9i Univ., Bebek, given acousticmodel of the oceanand the data measuredat an arrayof 80815Istanbul, Turkey) sensors.The correlationsare madeusing an assortmentof linear and non- linearmethods. These techniques were successfully tested using simulation In viewof a recentextensive review concerning wave propagation in porousmedia [M. Y. Corapcio•lu,in TransportProcesses in PorousMedia for the relativelysimple problem of localizinga harmonicpoint force on a simply supportedlaterally vibrating beam. Wave equationsolutions for (Kluwer,Dordrecht, 1991), pp. 373-469], this paper presents a theory for describingthe vibration of morecomplicated structures (simulated by add- the dynamicresponse of a multilayerplate within the frame of Biot's ing springconstraints to the beam)become, at somepoint of complexity, theoryof elasticityand consolidation for a porousanisotropic solid [M. A. Blot,J. Appl.Phys. 26, 182-185 (1955)].The multilayerplate may com- intractable.Often statisticaltechniques provide the only practicaldescrip- priseany numberof bondedlayers, each with a distinctbut uniformthick- tion of suchstructural vibration problems. Multiple constraintMFP meth- ods, tolerant to solution mismatch, were used to deal with these more nessand anisotropicelastic properties. A differentialvariational principle [G. A. Altayand M. C. D/Skmeci,J.Acoust. Soc. Am. 95, 3007(A) (1994)] complicated structures.Finally, it was demonstratedthat MFP methods might alsobe usedas a meansof nondestructivetesting in orderto locate for Biot'stheory together with Mindlin'splate kinematics for eachlayer is defects. usedto derivethe two-dimensionalapproximate equations of multilayer platein invariantdifferential and variational forms. All the continuitycon- ditionsbetween the interfacesof layersare taken into account. The gov- erning equationsare capableof predictingthe extensional,flexural, tor- 8:15 sional,and coupledvibrations of multilayerportelastic plates. Special 3aSAa2. The phasegradient methodapplied to the plate: Analysisof casesinvolving the geometry, material, and motions of multilayerplates the partial derivatives with respect to the phase velocities. O. are studied.The resultscontain some of earlierones as specialcases. Lenoir, J. M. Contit, and J. L. Izbicki (Lab. d'Acoust. Ultrason. et [Worksupported in part by TOBA-T'0BiTAK.] d'Electron. LAUE, URA CNRS 1373, Univ. du Havre, P]. Robert Schuman,76610 Le Havre, France) 8:45 The phasegradient method is a convenienttool in orderto analyzethe 3aSAa4.Mode shapeand eigenfrequencyspectra of elasticplates in frequentialand angular resonances of an immersedelastic plate [J. Acoust. the vicinity of the thickness resonancefrequency. Victor T. Soc.Am. 94, 330-343 (1993)].It consistsin thestudy of thederivative of Grinchenko (Inst.of Hydromech.,Natl. Acad.of Sciences,Kiev 252057, the phaseof the reflectioncoefficient with respectto the frequency U•aine) x--the obtainingof the resonancefrequency x* and the resonancewidth F* is thenstraightforward---or withrespect to theangular parameter y A numberof experimentalinvestigations have been performed to study (whichis thesine of theincidence angle). It is shownthat the derivatives vibrationcharacteristics of elastic plates in a high-frequencyregion. Up to with respectto the differentphase velocities involved in the scattering thistime theempirical data have no satisfactoryexplanation in termsof problemalso permit the isolationof the resonances.The derivativeswith Lambwave coupling. The theoreticalanalysis of thecoupling effects pre- 2518 J. Acoust.Soc. Am., Vol. 9g, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2518 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 in the article is based on the exact solution of the free-axis- 9:30 symmetricvibration problem for a circularplate. Consideration of a spe- 3aSAa7. Robust feedback control of flow-induced structural cial caseof zero Poisson'sratio allows one to distinguishand investigate radiation of sound. Craig Heatwole,Matthew A. Franchek,Robert J. threeindependent kinds of eigenmodes.Two of themare initiatedby sim- Bernhard,and Luc Mongeau (1077 Ray W. Herrick Lab., Schoolof ply propagatedlongitudinal waves. The waveswith complexwave num- bers(evanescent standing waves) provide a rise to a third type of eigen- Mech.Eng., Purdue Univ., West Lafayette, IN 47907) form. Eigenfrequenciesof theselast modesare very closeto the thickness A significantcomponent of the interiornoise of aircraftand automo- resonancefrequency and they increaseas radiusof a plate increases.The biles is a resultof the turbulentboundary layer excitation of the vehicular data for nonzeroPoisson's ratios demonstrate an influenceof couplingon structure.In thisinvestigation the feasibility of activecontrol of wind noise a structureof eigenfrequencyspectra and mode shape.An investigationof is studied.Initial studiesare made by consideringthe idealized case of radiusvariation efl•cts gives a good indicationof the feasibilityof the soundradiation from a simply supportedpanel excited by a turbulentflow couplingeffect control.The valuesof the plate radiuswith the moderate boundarylayer. To studyvarious control system alternatives, a wind noise [nodeshape disturbances are determined. modelis developed.The modelconsists of a modalmodel of the excitation of a platefrom a turbulentboundary layer, a modelof platevibrations, and a modelof the soundradiated from the plate.A frequency-domainap- proach,similar to quantitativefeedback theory, is utilizedin the designof 9:00 a robustfeedback controller. The controllerutilizes plate acceleration feed- 3aSAaS. Investigation of wave processes in a Timoshenko back while maintainingsound-pressure-level reduction as the primaryde- thin-walled beam of open section caused by the shock subjection of sign objective.The design method insuresthat performanceand control an elastic sphere upon its surface. Yuriy A. Rossikhin (Dept. of effort objectivesare met for plant and disturbanceuncertainty. The con- Theoret. Mech., Voronezh State Acad. of Constructionand Architecture, ul. troller designmethod offers flexibility in configuringthe size of the con- Kirova 3-75, Voronezh 394018, Russia) troller,and the effect of the performanceand controleffort objectiveson the controllerdesign are easily identified. The problemon the normalimpact of an elasticsphere upon an elastic Timoshenkobeam of thin-walledmonosymmetrical open section is con- sidered.The processof impactis accompaniedby thedynamic flexure and torsionof the beam,resulting in the propagationof planeflexural, shear, 9:45 and torsionalwaves of strongdiscontinuity along the beamaxis. Behind 3aSAaS.Adaptive controlof modular soundenclosure. Kyle Martini thewavefronts the solution is constructedin termsof one-termray expan- (CambridgeAcoustical Assoc., 200 BostonAve., Medford, MA 02155)and sions.During the impactthe spheremoves under the actionof the contact Ann Stokes (Boston Univ., Boston, MA) forcewhich is determineddue to the Hertz'stheory, but the contactregion moves under the action of the contact force, and the bending-torsional This paperpresents an experimentaldemonstration of the activecon- momentand transverseforces, which are subjectedto the lateralsurfaces trol of a novel, modularsound enclosure that is built of panelswhich are of the contactregion and are determinedusing one-term ray expansions. stiffnesscontrolled throughoutthe frequency range of interest.In this The joint considerationof the equationsof sphereand the contactregion range, traditional passive noise enclosuresare difficult to successfully motionleads to theAbel equationof secondkind in the rateof changeof implement.The designof the lightweight,stiff panelspermits active con- the value of the sphereand beamdrawing together.The solutionto the trol with a manageablenumber of actuatorsand sensors.The controltech- Abel equationwritten in the formof a seriesin termsof thisvalue allows niqueis the adaptive,feedforward, filtered-x approach. Adaptive control is one to determineall characteristicsof the sphereand beamshock interac- neededbecause realistic changes in the enclosuretemperature and struc- ! tion. tural resonanceswould degradethe performanceof fixed feedforwardfil- ters.The designof theenclosures makes this adaptive approach computa- tionallyfeasible. Two performancecriteria are evaluated:the minimization of the sum of the squaresof the accelerationsof the panels,and the 9:15 minimizationof certainsupersonic wave-number components of the sur- face vibrationfield. Both approachesare straightforwardfor thisenclosure 3aSAa6. Wave-number-based assessmentof the doubly asymptotic design,where each panel behaves like a piston.[Work supported by the approximation. Jerry H. Ginsbergand KuangchungWu (G. W. NationalScience Foundation.] WoodruffSchool of Mech. Eng., GeorgiaInst. of Technol.,Atlanta, GA 30332-0405) The mostwidely implementedtechnique for modelingfluid-structure 10:00 interactioneffects associated with shockresponse is the doublyasymptotic approximation(DAA}, whichhas been developed in a varietyof versions. 3aSAa9. An experimental study of active control of vibration Becauseof a lack of analyticalsolutions for realisticgeometries, prior transmissionin a cylindrical shell. Xia Pan and Colin H. Hansen validationefforts have not provideddefinitive guidelinesregarding the (Dept.of Mech. Eng.,Univ. of Adelaide,Adelaide, South Australia 5005, accuracyof the method.The presentwork usesNicholas-Vuillierme's Australia) derivation[Numerical Technique.• in AcousticRadiation, edited by R. J. Bernhardand R. E Keltie (American Society of MechanicalEngineers, An experimentalinvestigation of active controlof vibratorypower New York, 1989}, Vol. 6, pp. 7-13] of the frequency-domainversion of transmissionin a semi-infinitecylinder, using an array of electrodynamic DAA as the basisfor examiningthe accuracyand limitationsof DAA for shakers,is described.The cylinderwas ]nountedvertically in a sand-filled a slenderhemi-capped cylindrical shell. The developmentcomputes the box(I m in height)in an attemptto providea semianechoictermination at wet surfaceimpedance matrix relating surface pressure and velocityvari- one end. The other end was simply supportedusing a steel ring. The ablesover a broadfrequency band according to two DAA versionsand the cylinderwas excited near the simply supported end using a primaryshaker. surfacevariational principle. The alternativewet surfaceimpedanees are Controlwas implemented using three control shakers applied downstream usedto predictthe frequency-domainstructural response of the shellto a from the primaryshaker. Using threecontrol shaker• it is possibleto point force, after which alternativetime-domain responses are obtained achievea 7-dB reductionin powertransmission. Although 7 dB was the fromthe FI:T algorithm.Results for wave-numberamplitudes {azimuthal maximumpower reduction which could be obtainedtbr the experimental and meridional)are reportedfor moderateand large aspectratios. An equipment,the numericalsimulation shows that on a largescale, a reduc- overviewindicates that a higher-orderDAA versionoccasionally works tion of 30 dB couldbe obtained.Also, measurementof powertransmission extremelywell, butthat there is no consistenthigh/low trend as a function intensityin a cylinderusing two accelerometerswas investigated.The of wavenumber. [Work supportedby the Officeof Naval Research,Code resultsindicate a meansof simplifyingpower transmission measurements in largecylindrical structures. 2519 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2519 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 meci, IEEE Trans. Ultrason. Ferroelectr.Freq. Control 35, 775-787 (1988)]together with the solution is usedso as to derivethe system of 3aSAa10. A general dynamic theory of thermopiezoceramicshells. approximateequations of ceramicshell. The invariantsystem of governing G. A•kar Altay (Dept.Civil Eng.,Bo•azici Univ., Bebek, 80815 Istanbul, equationswhich are expressedin both differentialand variationalforms Turkey) and M. Cengiz Drkmeci (IstanbulTech. Univ.-Teknik Univ., accountsfor all the types of motionsof ceramic shells. Certain cases Taksim,80191 Istanbul,Thrkey) involvingspecial geometry, material properties, and motionsare coosid- This studypresents a generaltheory for the motionsof a ceramicshell ered[e.g., M. C. D/3kmeci,J. Math.Phys. 19, 109-126 (1978)].Also, the in which there is coupling among mechanical,electrical, and thermal sufficientboundary and initial conditionsare given for the uniquenessin fields.The coatedceramic shell is treatedas a two-dimensionalthermopi- solutionsof the fully lineafizedsystem of shellequations. The resultsare ezoelectricmedium and a separationof variablessolution in termsof the shownto generatea seriesof knownshell theories [e.g., M. C, Drkmeci, thicknesscoordinates, the midsurfacecoordinates, and time is soughtfor IEEE Trans.Ultrason. Ferroelectr. Freq. Control 37, 369-385 (1990) and its field variables.Then. a variationalaveraging procedure [M. C. Drk- referencestherein]. [Work supported byTOBA-TOB•TAK.] WEDNESDAY MORNING, 15 MAY 1996 CANYON HALL, 10:45 A.M. TO 12:00 NOON Session 3aSAb Structural Acousticsand Vibration: Radiation and Damping Gerard P. Carroll, Chair Carderock Division, Naval Surface Warfare Center,Bethesda, Maryland 20084-5000 ContributedPapers 10:45 for a largefrequency range, the quadratic velocity, the radiation efficiency, and the radiatedpower. Emphasisis then put on preciseexperimental 3aSAbl. Specific damping capacity for high-lossmaterials. Gilbert E Leeand Brace Hartmann (Naval Surface Warfare Ctr., Silver Spring, validation.A fully inslmmentedsetup using a laservibrometer for probing MD 20903) the displacementfield hasbeen developed. The basicplate is madeeither fromaluminum or fromresin epoxy. Using technical data furnished by the The purposeof this presentationis to establishthe relationbetween manufacturers,the comparisonbetween theory and experienceis ex- specificdamping capacity and lossfactor for high-lossmaterials. The mo- tremelygood in the caseof aluminum.Discrepancies are biggerfor the tivationfor thiswork is thatthe commonly used relationship between these resin epoxy and this aspectwill be discussed.Partial covering,which is variablesis only valid for low-lossmaterials and leadsto significanterrors alsoof greatpractical interest, will also be presentedfor both theoretical as the lossincreases. The relationshipcited in numerousreferences be- and experimentalaspects. tween specificdamping capacity is AWIW=2•r tan& This equationis only valid for very small valuesof 8. Anotherdifficulty with the above relationshipis thatthe specificdamping capacity is generallyassumed to representthe fractionof energyconverted to heat.For largevalues of tan 8, AWIW can be greaterthan one, whichseems to be a contradiction.In 11:15 this presentation,a relationshipbetween specific damping capacity and loss factor is derived, which is valid for all values of tan 8. In the limit as 3aSAb3. Internal-external measurement of three-dimensional the loss factor approachesinfinity, the specificdamping capacity ap- velocitiesof a submergedshell by optical vibrometry. Joseph proachesunity. A comparisonof our relationshipwith othersfound in the Vignola, P. Frank, L. Leka (SFA, Landover,MD 20785), Harry literaturewill be presented.[Work supported by Naval SurfaceWarfare Simpson, and Brian H. Houston (Naval Research Laboratory, Center'sIn-house Laboratory Independent Research Program sponsored by the Office of Naval Research.] Washington,DC 20375-5000) A uniqueexperimental capability for measuringboth the interiorand exteriorthree-axis surface motions of a completelysubmerged ribbed cy- lindricalshell has been developed. This system is composedof twothree- 11:00 dimensionallaser Doppler vibrometers positioned by a pair of high- 3agAb2. Precise formulation of the vibroacoustic effects of an added precisionrobots. The two vibrometerswork together to measurethe three- constrained damping layer on a plane structure. lean Nicolas, componentsof velocity up to 50 kHz on both the interior and exterior NoureddineAtalla, Olivier Foin, and BertrandMercier (Mech. Eng. cylindersurfaces. For theinterior, a compactthree-dimensional vibrometer Dept., Univ. de Sherbrooke,Sherbrooke, PQ J1K 2R1, Canada) wasdesigned and constructed to operatein conjunctionwith a cylindrical- basedscanner mounted to the stiff endcapsof the shell.This scanning The model proposedhere describesthe SAV behaviorof a sandwich systemis capableof positioningthe laservibrometer with a precisionof plate(elastic-visoelastic-elastic) and usesthe following hypothetisis, in- +/- 3 rail over 100% of the interior cylinder surface.A secondthree- spiredby the discretelayer theory:The viscoelasticlayer takes into ac- countbending, shear, and traction compression; normal strain and torsional dimensionallaser vibrometer designed for exterior(in-water) operation motionare neglected; using the eominuity of the displacementat the vi- wasconstructed and integrated into the NRL near-fieldacoustic hologra- soelasticlayer interfaces, the displacement field of theviscoelastic layer is physystem. This large workspace Cartesian-based scanner is capableof writtenas a functionof the elasticlayer displacementfield. A variational collocatingthe focal point of the exteriorvibrometer with that of the methodis usedto findthe displacement equations. The radiation imped- interiorto within+/- 10 rail.The design of thesystem will bediscussed, anceis calculatedvia a formulationrecently proposed by Atalla and Nico- andstructural acoustic data will bepresented from a seriesof preliminary las[J. Acoust. Soc. Am. (1994)]. This formulation allows one to calculate, experimentsconducted to evaluatethe performance of the system. 2520 J.Acoust. Soc. Am., VoL go, No. 4, Pt.2, April1996 131stMeeting: Acoustical Society of America 2520 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 velocitysignals. These findings contrast previously reported predictions of the level of acousticallyinduced error for largestand-off in-water LDV 3aSAb4. Acousto-opticphase modulation of a laser Doppler designs.[Work supported by ONR.] vibrometersignal resultingfrom the radiated pressureproduced by a submerged cylindrical shell: Numerical predictions and 11:45 experimentalresults. Harry J. Simpson,Joseph Vignola, Martin H. Marcus. and Brian H. Houston (Naval Res. Lab., Code 7136. 4555 3aSAb5. Fractal sound radiation by layered elastic structures. OverlookAve.. W•tshington.DC 22375} LeonidM. Lyamshev (N. N. AndreevAcoust. Inst., ShvemikSte. 4. 117036 Moscow,Russia) It has been proposedthat large stand-offlaser Doppler vibrometer A generalmethod of calculationof soundradiation by layeredelastic (LD¾) measurementshave significanterrors resulting from indexof re- structuresis developed.The reciprocitytheorem formulated by the author fractionmodulation due to the acousticpressure distribution along the laser in 1958 is used. It is shown that plane structuresound radiationsare lightpaths between the structureand the probe[Y, H. Berthelotet al., J. determinedby externalacting forces and the structuretransmission coef- Acoust.Soc. Am. 97, 3347(A)(1995)]. A highfidelity numerical model ficient.The methodis very convenientfor the analysisand calculation hasbeen used to predictthe pressuredistribution and shell motionsfor a sincethe externalforce characteristics are givenand the transmissionco- submergedfinite ribbed cylinder under point excitation. Generally speak- efficientis a knownfunction of impedancesof layers.Several particular ing, thesepredictions show low levelsof contaminationeven for large problemsare considered.Sound radiation by a thin plateor a thickthree- stand-offprobe distances. In addition.an experimentalstudy has been layeredstructure are consideredwhen concentrated or fractaldistributed conductedat NRL usinga newly integratedthree-axis vibrometer and statisticalexternal forces act. The methodfor movingmedia in layersis near-fieldpressure probe where shell motions and near-fieldpressure dis- generalized.Sound radiation by curvedinhomogeneous layered structures tributionswere measuredfor the caseof a submergedribbed cylinder is discussed.The planestructure formula, Green's theorem, and the Kirch- underpoint excitation. The experimentsand the associatednumerical mod- hoff approximationare usedin last cases.Sound radiation fractal charac- eling both indicatelow levelsof acousto-opticcontamination of the shell teristics are discussed. WEDNESDAY MORNING, 15 MAY 1996 REGENCY D, 8:15 A.M. TO 12:15 P.M. Session 3aSC SpeechCommunication and Musical Acoustics:Speech and Music: Exchangeof Ideas, Methods and Findings Barbara Acker, Cochair Centerfor Cognitiveand PsycholinguisticSciences, Binghamton University, Binghamton, New York13902-6000 Richard E. Pastore,Cochair PsychologyDepartment, State Universityof New York,Binghamton, New York 13902-6000 Chair's Introduction4:15 Invited Papers 8:25 3aSCl. Perceivingand encodingtimbre. Mark A. Pitt (Dept.of Psychol.,1885 Neil Ave. Mall, OhioState Univ., Columbus, OH 43220) Interactionswith the auditoryenvironment often require accuraterecognition of soundobjects and events(e.g., voicesand instruments,and the utterancesthat emanate from them). Two linesof researchin the lab havebeen exploring how listenersprocess the auditorydimension of timbreas one steptoward understanding object recognition. In one,commonalties in processingdifferent classesof timbres(human voices, musical instruments) using the selectiveadaptation paradigm are explored.In the second,the characteristicsof timbre memory using the interpolatedtone paradigm are examined [Deutsch. Science 168, 1604-1605].Findings will be discussed in the context of similar results in the literature. 8:50 Commentary by Paul lverson and Michael D. Hall Dept. Speechand Hear. Sciences.Univ. of Washington.Seattle, WA 98195 9:05-9:15 Discussion 9:15 3aSC2. Perceptualanchors and magnetsin infancy, SandraE. Trehub (Llnlv.of Toronto,igrlndale Campus, Misslssauga, Obl LSL IC6, Canada) Researchon adults' and children'sperception of tone sequencesor melodiesreveals that they more readily detectthe same magnitudeof changein the contextof a "good"or well-formedsequence than in the contextof a "poor" or lesswell-formed sequence. Becausewell-formedness is typicallyconfounded with familiarity,the originof suchperfom•ance asymmetries often remains unclear. in recentstudies, however, 6-month-olds exhibited adult-like patterus of performance,raising the possibilityof processingpredispo- 2521 d. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society of America 2521 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 sitionsfor goodauditory sequences. Such sequencescould be considered"natural" prototypes, and would be expectedto occur frequentlyacross cultures. Natural prototypesmight serve a perceptualanchoring function for novice and experiencedlisteners, facilitatingthe acquisitionof certainkinds of information.Kuhl argues,however, that phoneticprototypes operate differently, being lessdiseriminable from othersounds within the samecategory than are nonprototypes.In otherwords, the goodinstances function as magnetsrather than anchors. On the one hand,it is usefulfor naturalprototypes to functionas anchors,being highly distinctiveand memorable.On the otherhand, sufficient flexibility is necessaryfor the acquisitionof culture-specificor "magnetic"prototypes. 9:40-9:55 Commentary by Peter W. Jusczyk Dept. of Psych.,SUNi r at Buffalo,Buffalo, NY 14260 9:55-10:05 Discussion 10:05-10:20 Break 10:20 ß3aSC3. Musical communicationand theoriesof the stimulus. CarolinePalmer (Dept. of Psychol.,1885 Nell Ave. Mail, Ohio . StateUniv., Columbus,OH 43220) Is the stimulusfor musicperception an abstractform of a musicalpiece. or a particularperformance of it?As with language,music reflectsa communicationof structureamong its users(composers, performers, and listeners), which suggests the existenceof some sharedmusical knowledge. Music performancemay be an indispensablesource of evidencefor theoriesof that sharedknowledge. becausethe particularexpression given in eachperformance guides our musicalunderstanding. Different sources of knowledgein musicperformance that contribute to a theoryof thestimulus for perceptionwill be described.Evidence from both expressive nuances of performanceand from productionerrors (unintended mistakes) converge on the sameknowledge sources. These performance findingshave correlates in bothmusic perception and in otherproduction domains, such as speech.[Work supported by NIMH and NSF.] 10:45-11:00 Commentary by William Forde Thompson Dept. of Psych.,Atkinson College, York Univ., ON, Canada 11:00-11:10 Discussion 11:10 3aSC4.Music and speechin a neuropsychologicaiperspective. Isabelle Peretz (Dept.of Psychol.,Univ. of Montreal,CP 6128, Centre-ville, Montreal, PQ H3C 3J7, Canada) Neuropsychology-- definedas the studyof the relationsbetween brain organization and mentalfunctioning -- has concerned itself from its earliestdays with the processingof speechand music.The first stepswere taken in the speechdomain, via the observationof selectivespeech impairments following damage to specificareas of thebrain (Broca, in VonBenin, Some Papers on theCerebral Cortex; Wemicke, in BrainFunction 3, 1-16). Theseinitial findings swiftly prompted the exploration of musicdisorders (Bouillaud,Bull. Acad. Med. 30, 752-768). Such observations arelabeled aphasia and amusia, respectively, and reflect a long-standing concernto describethe selectivity of thedisorders observed. This issue of specificityis evenmore prevailing/acute in contemporary neuropsychology,with theadvances made in brainimaging and in experimentalpsychology. Current knowledge will be summarized andorganized along two main questions: (1) Is music.like speech. subserved by neutralcircuitries devoted to itsprocessing9 (2) Vqlaat are the boundariesof neuropsychologicalseparability between music and speech? 11:35-11:50 Commentaryby KennethPugh Haskins Labs. and Yale Medical School, New Haven, CT 11:50-12:00 Discussion 12:00-12:15 Open Discussion 2522 J. Acoust.Soc. Am., Vol. 99, No.4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2522 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, 15 MAY 1996 CELEBRATION B, 8:15 TO 11:50 A.M. Session 3aUW UnderwaterAcoustics: Propagation Andrew A. Piacsek, Chair LawrenceLivermore National Laboratories,L-200, P.O. Box 808, Livermore,California 94550 Chair's Introduction•:15 ContributedPapers 8:20 8:50 3aUW1. Reproducibility of low-frequency shallow-water acoustic 3aUW3. Interference patterns of frequency-dependentlransmission experimental data. RichardB. Evans (SAIC, 21 MontaukAve., Ste. loss for shallow-water propagation. Kevin P. Bongiovanni,Mobsen 201, New London,CT 06320) and W. M. Carey (ARPA, Arlington,VA Badicy (GraduateCollege of MarineStudies, Univ. of Delaware,Newark, 22203) DE 19716), and William L. Siegmann (RensselaerPolytechnic Inst., Troy, NY 12180} Transmissionloss measurementswere conductedin September 1993 on the continentalshelf off New Jersey.Low-frequency continous-wave Transmissionloss (TL) asa functionof frequency,for fixedsource and data were recordedon a verticalline receivingarray in approximately73 receiverpositions, provides a meansto investigatethe influenceof envi- m of water.The geometryof thesemeasurements replicates the geometry ronmentalmechanisms on broadbandacoustic propagation. These curves of experimentalmeasurements conducted during October 19õg al thesame exhibitan analogousbehavior to cw losscurves as a functionof range, site and undersimilar downward refracting conditions. The setsof fre- quenciestransmitted during the two experimentswere different, but cov- with null-peakinterference patterns observed in both experimentaldata ered the region legsthan I kHz. Acousticsurveys and geophysicaldata and numericalsimulation. An analyticapproximation for the resultingpat- obtainedin 1988 provideddetailed characterizations of the qeabed.The ternsin a Pekeristype range-independentmedium employing normal- bottomcharacterization is assumedto be time invariant,except for the modetheory is developed.Broadband signals are partitioned into bands for contributionof the pore fluid to the uppermostlayers of the sediment. whichaccurate modeling can be achieved.Narrow-band approximations Consequently,the characterization of theseabed should be valid whenthe are thenused to deriveformulas for the null-spacingsof the curves.These bottomwaters are similar. The coincidenceof the two setsof experimental expressionsconnect the interferencestructure, through the modalgroup data and a valid geoacousticmodel provide the opportunityto test the velocitiesand appropriateboundary conditions, to volume and seabed reproducibilityof theseresults. The bottomcharacterizations based on two slrucmreand composition. This workextends a previousdevelopment for setsof acousticdata are comparedwith expectationsbased on profiles a zeroth-orderocean [Badicy et al., J. Acoust.Soc. Am. 98, 2897(A) derivedfrom geophysicaldata. (1995)].A qualitativeassessment of the formulation is achievedby com- parisonswith both parabolicequation simulations and high-resolution geoacoustic/acousticexperimental data, for severaldifferent environments. The evolutionof TL versusfrequency patterns in rangewill be discussed in light of range-dependentenvironmental parameters. 8:35 3aUW2. Recent shallow-water acoustic measurements of sound transmission,reverberation, and coherence. William M. Carey (Adv. Res.Projects Agency, 3701 N. FairfaxDr., Arlington,VA 22203),Peter 9:05 Cable, and Mike Steele (BBN Systemsand Technol.,Arlington, VA 22209) 3aUW4. Statisticalanalysis of broadbandpropagation in shallow water. Mohsen Badicy, Simon A. Shaw, Kevin P. Bongiovanni, Recentexperiments performed in theshallow waters (100 m deep)of ThomasC. Honsinger,and Joe R. Zagar (OceanAcoust. Lab., Graduate the Gulf of Mexico, East Continental Shelf of America, and the Korean Collegeof MarineStudies. Univ. of Delaware,Newark, DE 19716) Straitsunder the conditionof downwardrefraction with sandy-siltyclays arediscussed. These experiments were performed with bothexplosive, air Oneof the mostimportant issues facing ocean acoustic experimental- gun, and continuoussources covering the 100•Hz to 1-kHz frequency isiswhen attempting to performcalibrated experiments is distinguishing range.The receiverswere both horizontal arrays on thebottom and vertical measurement errors from environmental variabilities. These errors include arrayswhich spanned the water column. Precise navigation was employed to eliminaterange uncertainties and all measurementsystems were cali- accuracyof monitoringhydrophones, ship positioning (hanging sources}, bratedto a traceablestandard. The resultsare presented in the categoriesof and,for a broadbandsource in particular,spectral level and phasevaria- sound transmission,reverberation, and coherence.Sound transmissionre- tionsof the source.Statistical analysis is usedto investigatethe repeat- sultswere found to generallyagree with wave-theorefcnumerical codes abilityof sourceand receiver signatures collected from a seriesof broad- and shearwas not foundto be important.The reverberationwas foundto band experimentsperformed in very shallowwater at the Atlantic havea frequency-dependentcharacteristic consistent with sedimentlayer- GeneratingStation (AGS) site. Classification of thefactors inducing signal ing.Coherence lengths are estimated from array signal gain measurements variation, which may arise from surfaceand bottomroughness and time- in themidfrequency range and compared to previousmeasuremenls in both varyingvolume inhomogeneities. in addition to sourceerrors. is madefor deepand shallow water. Results were found to be influencedby a variety severalexperimental configurations. It is shownthat the coherence of the of factorssuch as watercolumn variations. Estimates of the importanceof receivedsignals is directlyrelated to the environmentaleffects on the thesefactors under downward refracting conditions will be madeand ex- acousticwaves and the shot-to-shotcorrelation decreases with increasing tendedto othersound velocity profiles. range. 2523 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2523 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 9:20 10:05-10:20 Break 3aUWS. Frequency dependenceof forward propagationthrough a layereddipping sediment. RogerM. Oba (Naval Res. Lab., Acoust. Div., Washington,DC 20375) Forwardpropagation is usedto computethe acoustic field in a shallow- 10:20 water environmentwith a layereddipping sediment. The sedimentis as- 3aUW8. Acoustic propagation through a low Much number, sumedto be silty with severalthin sandylayers with higherdensity and stratifiedflow. PierreElisseeff and Henrik Schmidt (Dept. of Ocean soundspeed. The sandylayers slope within the entiresediment layer so Eng., MIT, Cambridge,MA 02139) that the depthof a sandlayer varieslinearly with range.The sedimentis modeled as a fluid of uniform horizontalthickness over a range- Propagationof soundin an oceanicwaveguide in thepresence of a low independenthard sub-bottom. The watersound speed is rangeindependent Much number,stratified flow is investigated.Equations for the wavenum- and depthdependent in a fixed depthenvironment. This range-dependent ber integration(WI) and normalmode (NM) approachesare simulta- sedimentgeometry leads to transmissionloss significantlydifferent from neouslyderived in a singleformulation. When hydrodynamicshear stress thosewith fixed layer depths,even when the dip gradientis very slight. and acousticazimuthal coupling are negligible,the effectof currentcan be Thesedifferences and their mechanisms are explored for varyingfrequen- accountedfor by a simplemodification of existingWI and NM codes.A cies and interlayerdistances. currentlayer is then shownto act as a wave-numberfilter which, in some cases,cannot be modeledusing an equivalentsound-speed profile. Broad- bandnumerical simulations show very goodagreement between indepen- dently modifiedversions of OASES and KRAKEN. Applicationsto to- mographyare eventuallydiscussed. The acousticfield for smoothcurrent 9:35 profiles can be derived as a function of the medium-at-restmode set, 3aUW6. A study of the influence of an off-shore rise on makinga broadbandinversion possible. [Work supported by ONR.] low-frequencymodal propagationwith Arctic surface loss. Thomas N. Lawrence,Wade Trappe, and NancyR. Bedford (Appl. Res. Labs., Univ. of Texas,P.O. Box 8029, Austin,TX 78713) Simple up-slopepropagation of underwateracoustic energy can usu- 10:35 ally be modeledby an adiabaticnormal mode approximation, provided the slopeis not too severe.Bottom interacting paths in suchan environment 3aUW9. Invariant imbedding analysis of seabed acoustics. areusually sufficiently attenuated to makeconsideration of mode coupling KhaldounKhashanah (Dept. of MathematicalSciences, Stevens Inst. of unnecessary.An environmentfnrtber complicated by an off-shorerise can Technol.,Hoboken, NJ 07030) andThomas G. McKee, Jr. (StevensInst. causeadditional acoustic energy to be introducedinto lower-ordermodes of Technol.,Hoboken, NJ 07030) due to bottominteraction. These low-order modes will thenpropagate in deep water until encounteringthe continentalsbelf. Experimentalresults The linear acousticequations for the boundedslab of fluid oceanand from the Arctic Oceanbetween 25 and 45 Hz suggestsuch propagation elasticseabed with cylindericalsymmetry are reduced to a setof coupled conditions.These results, and their interpretationin the context of a boundaryvalue problemsusing separation of variables.In orderto havea coupledmode study, will be presented.Environmental parameters and computationaltechnique capable of handlingstratification effects in the sourcedepth will be varied to explore under what conditionsmode cou- seabed,invariant imbedding is usedto replacethe boundary value problem pling can be ignoredwhen consideringdetection and localizationprob- with an initial valueproblem. As an initial approximation,the caseof an lems.Arctic surfaceloss will be appliedto the modelingresults to show oceanwith a reflectivebottom is consideredand the changein the solution, how modevarying attenuation will affectthose results. The coupledmode as the depthof the seabedincreases, is calculated.The methodof invariant model(COUPLE) [R. B. Evans,J. Acoust. Soc. Am. 74, 188-195 (1983)], imbeddingis shownto be numericallystable and has the advantageof is usedas the vehicle for thisstudy. [This work is sponsoredby SPAWAR assessingthe effectsof includingan interactiveseabed on the solutionto PMW 182-2.] the underwateracoustics problem with a reflectingseabed. 9:50 10:50 3aUW7. Improved narrow-band and broadband normal-mode 3aUW10. Mode coupling analysisfor a resonanceeffect due to an algorithmsfor fluid oceanenvironments. Evan K. Westwood(Appl. internal solitoh. Michael K. Broadheadand Robert L. Field (Code Res. Labs., Univ. of Texas,P.O. Box 8029, Austin, TX 78713-8029) 7173, Naval Res.Lab., StennisSpace Center, MS 39529-5004) Improvementshave been achievedin the speed,robusmess, and ver- As pointedout by Zhou et aL [1. Acoust.Soc. Am. 90, 2042-2054 satility of a recentlydeveloped normal-mode algorithm for fluid ocean (1991)],nonlinear shallow-water solitary internal waves (SIW's) can en- environmentsiS. J. Levinsonet aL, I. Acoust.Soc. Am. 97, 1576-1585 hancethe bottom interaction of underwatersound. For a 1ossyocean bot- (1995)].The possibility of missingmodes has been eliminated by comput- tom,this has the effect of a levelchange (in additionto fluctuations)in the ing both the total phaseof the oscillatorymode function versus depth and transmissionloss at preferredfrequencies. The mechanismfor thiseffect is the numberof zerosof the function.The root-findingalgorithm computes acousticmode coupling due to thedepression of highersound-speed water bothan errorfunction and its derivative,which allows cubic interpolation into lower speedwater (at the pycnocline).It is alsopossible for this to be used to obtain eigenvalae guesseswhen, a feet is bracketed. The i•cwh/tiiias•tto inducea transferof acousticenergy trom belowthe ther- efficiencyof the root-finderis characterizedby the fact that the error moolineinto the mixed layer,as hasbeen shown elsewhere, where a two- functiontypically must be computedless than 3-1/2 timesper mode.An layer pycnocline/sound-speedenvironment was used, along with a KdV automatedbroadband capability has also been implemented. Analytic first soliton.Over the frequencyrange studied (900-1030 Hz), the energy andsecond derivatives are used to interpolatethe eigenvalues in frequency transferspectrum exhibited a doubletresonant structure. It wasalso found as a fifth-orderpolynomial. For broadbandcomputations where inclusion thatan increasein the S1Wlength scale was accompanied by a positive of thecontinuum is desired, a falsebottom may be automaticallyinserted. shiftin theresonant frequencies. A simple model is offeredthat qualita- Its thicknessis specifiedin termsof acousticwavelengths in the medium tivelyaccounts for thesetwo featureswhich is basedon modecoupling andvaries with the frequency, thus saving the computation of a significant theory.Also presented is thedependency of the resonance frequencies on numberof modes.[Work supported by ONR 321OA.] the soundspeeds and layerthicknesses of the acousticenvironment. 2524 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt.2, April1996 131stMeeting: Acoustical Society of America 2524 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 lateover long propagation paths, and are accentuatedat convergencezone caustics.The goalsare to estimate(1) levelsof harmonicgeneration in 3aUWll. Nonlinear wide-angle paraxial propagation in oceantomographic experiments and (2) waveformsteepening in underwa- shallow-waterchannels. Rahul S. Kulkarni,William L. Siegmann ter explosions.Harmonic generation (1) is estimatedfrom a linearbaseline (RensselaerPolytechnic Inst., Troy, NY 12180-3590),and Michael D. solutioninvolving vertical eigenmode expansion. The resultimplies sec- Collins (NavalRes. Lab., Code 7140, Washington, DC 20375-5320) ond harmonic magnificationat odd numberedconvergence zone ranges. A model that describeswide-angle paraxial propagationof acoustic Waveformsteepening (2) is estimatedby time-domainnumerical integra- pulses in shallow water has been developed. This time-domain, range- tion and relatedto modalexcitation differences in the far field [J. Ambro- marchingmodel incorporatesweak nonlineareffects and depthvariability siano,D. R. Plante, B. E. McDonald, and W. A. Kuperman,J. Acoust. Soc. in both ambientdensity and soundspeed, with extensionsto includedis- Am. 87, 1473-1481 (1990)]. [Work supportedby ONR.] sipativeeffects. The derivationis basedon an iterativeapproach, in which the wide-angleapproximation is obtainedby using a narrow-angleequa- tion to approximatethe secondrange derivative in the two-waynonlinear 11:35 wave equation.Scaling argumentsare used to obtain a more tractable simplificationof theequation. Higher-order approximations can be derived 3aUW13, Propagationof signalsfrom strong exploslonsabove and by continuingthe iterativeprocedure. The wide-angleequation is solved below the ocean surface. DouglasB. Clarke, Andrew A. Piacsek,and numericallyby splittingit into componentsrepresenting distinct physical JohnW. White (LawrenceLivermore Natl. Lab., L-200, P.O. Box 808, processesand employinga predictor-correctorstrategy. A high-orderup- Livermore,CA 94550) wind flux-correctionmethod is usedto handlethe nonlinearcomponent, in In supportof theComprehensive Test Ban, research is underwayon the order to eliminatespurious artifacts that otherwisedegrade the solution. long-rangepropagation of signalsfrom nuclearexplosions in the deep Numericalresults are presentedfor differenttypes of sourcesin several underwatersound (SOFAR) channel.Our work hasemphasized the varia- horizontallystratified environments. Effects of nonlinearitieson wide- tion of waveproperties and source region energy coupling as a functionof angle propagationand differencesbetween narrow- and wide-anglenon- heightor depthof burst.Initial calculationson CALE, a two-dimensional linearpropagation will be discussed.[Work supported by ONR.] hydrodynamicscode developed at LLNL by RobertTipton, were linked at a few hundred milliseconds to a version of NRL's weak shock code, NPE, 11:20 whichsolves the nonlinearprogressive wave equation [B. E. McDonald andW. A. Kuperman,J. Acoust.Soc. Am. 81, 1406-1417(1987)]. The 3aUW12. Estimation of nonlinear effects in global scale ocean wave propagationsimulation was then followed down to 5000-m depth acoustic propagation. B. Edward McDonald (Naval Res. Lab., and out to l0 000-m range.In the future,calculations on a linear acoustics Washington,DC 20375) codewill extendthe propagationto greaterdistances. Until recentlyour The nonlinearprogressive wave equation (NPE) [B. E. McDonaldand researchhas consideredonly explosionsin or abovethe deepocean. New W. A. Kuperman,J. Acoust.Soc. Am. 81, 1406-1417(1987)] is usedto resultson energycoupling and signal propagation in shallowwater and the derivequantitative estimates for the magnitudesand characteristic features effectsof otherimprovements will be presented.[Work performed under of nonlinearitiesgenerated by finite amplitudeacoustic signals during the auspicesof the U.S. Departmentof Energyby the LawrenceLiver- propagationacross ocean paths of globalscale. Nonlinear effects accumu- moreNational Laboratory under Contract W-7405-ENG-48.] WEDNESDAY MORNING, 15 MAY 1996 EXECUTIVE BOARDROOM, 9:00 A.M. TO 12:00 NOON Meetingof AccreditedStandards Committee S2 on MechanicalVibration and Shock to be heldjointly with the U.S. TechnicalAdvisory Group (TAG) Meetingfor ISO/TC 108 MechanicalVibration and Shock D. J. Evans, Chair S2 NationalInstitute of Standardsand Technology,Acoustics, Mass and VibrationsGroup, Building 233, RoomA147, Gaithersburg,Maryland 20899 D. E Muster,Chair, U. S. TechnicalAdvisory Group (TAG) for ISO/TC 108,Mechanical Vibration and Shock 4615 O'Meara Drive, Houston, Texas 77035 StandardsCommittee S2 on MechanicalVibration and Shock.Working group chairs will presentreports of theirrecent progress onwriting and processing various shock and vibration standards. There will be a reporton the interface of S2activities with those of ISO/TC108 (the Technical Advisory Group for ISO/TC 108 consists of membersof S2,S3, and other persons not necessarily members of thosecommittees), including a report on the activities of ISO/TC108, with the plans for its September 1996 meeting in Sydney, Australia. Scopeof S2.Standards, specifications, methods of measurementand test, and terminology in thefields of mechanicalvibration and shock,and condition monitoring and diagnostics of machines, but excluding those aspects which pertain to biologicalsafety, tolerance and comfort. 2525 d. Acoust.Soc. Am., Vol. 99, No.4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2525 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, 15 MAY 1996 CIRCLE THEATER, 2:00 TO 3:00 P.M. Session3pAA Architectural Acousticsand Musical Acoustics:Directivity of Musical Instruments II Uwe J. Hansen, Chair Departmentof Physics,Indiana State University,Terre Haute, Indiana 47809 Chair's Introduction---2:00 Invited Paper 2:05 3pAA1. The influenceof directivityon soundheard by an audienceduring an orchestralperformance. JfirgenMeyer (Phys.- Tech.Bundesanstalt, Bundesallee 100, D-38116 Braunschweig,Germany) For a listenerseated in a hall, soundimpressions are createdby the time structureand the intensityratios of direct sound,early reflections,and reverberation.The intensityratios betweenthese components depend on the directivityof the soundgenerated by differentinstruments. Even for high-pitchedinstruments, omnidirectional radiation is found only at frequenciesbelow 500 Hz. The strengthof the directivitycan be describedby the statisticaldirectivity factor which fixes the angle-dependentreverberation radius of a sourcesounding in a hall. For directionsof main radiationat upperstring frequencies it is of the orderof 2-3; for the woodwinds, it is a little lower;for thebrasses it exceeds4. Directionsof strongradiation oriented toward the sidewalls,thus supporting the space impression,are found with the strings,bassoons, horns, and trombones. High-frequency components of stringsare radiated in strong measureagainst the ceiling:These reflections support the brilliancy.These sound effects will be demonstratedwith a real orchestra. WEDNESDAY AFTERNOON, 15 MAY 1996 REGENCY BALLROOM, 12:45 TO 1:50 P.M. Session3plD Interdisciplinary: Hot Topics in Acoustics Mauro Pierucci, Chair Departmentof Aerospaceand EngineeringMechanics, San Diego State University,San Diego, California 92182-1311 Chair's Introduction---12:45 Invited Papers 12:50 3piP1. A hot topicin musicalacoustics: Phase coherent representation of radiatedsound fields. Uwe J. Hansen (Dept.of Phys., IndianaState Univ., Terre Haute, IN 47809) A techniqueused to studynormal-mode vibrations in musicalinstruments is modalanalysis. This experimentalmethod analyzes a seriesof transferfunctions which relate the frequency spectra of a numberof impactpoints to thespectrum of a fixedresponse point, andsubsequently presents the motion of thestructure at thevarious normal-mode frequencies in computeranimation. This approach is extendedto representa radiated sound field by usinga fixedexcitation point on the musical instrument as the reference signal and monitoringthe sound field with a microphoneat a numberof predeterminedpoints. This makes it possibleto relatethe phase of the soundfield to the phaseof thevibrating structure responsible for generatingthat field. Animated illustrations will he shownfor the air columnin a wind instrumentand for the soundfield of a concertgrand piano. 2526 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2526 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 3plD2. Hot topicsin engineeringacoustics. StevenGarrett (GraduateProgram in Acoust.and Appl. Res. Lab., PennState Univ., P.O. Box 30, StateCollege, PA 16804) Engineeringacoustics attempts to utilizecontemporary developments in manyareas of science,technology, and analysis to produce acousticalsystems and products which address existing needs or createnew opportunities. Topics in engineeringacoustics become "hot" whenthere is a convergencewhich facilitates a "quantumleap" in someparticular application area. Fusion of new sensor technologies,microprocessors, signal processing, and electronic data communication has produced new options in condition-based monitoringof machineryand industrial processes. Advances in thespeed and reduction of costin A-D andD-A converters,coupled withhigh memory density, has permitted the development of acoustictime reversal mirrors which could have application to ultrasonic nondestructiveevaluation of materials.Computing power, new inversion algorithms, and novel transducers have led to the commer- cializationof resonantultrasound spectroscopy which can determine the complete set of elasticmoduli for materialswith samplesizes whichcan be lessthan I mg.The availabilityof fast,accurate one-dimensional computer-based acoustic modeling tools and new researchresults in studiesof the transferto heatfrom acoustically oscillating fluids to solidsurfaces are providing a newfoundation to designand optimize the nextgeneration of thermoacousticengines and refrigerators. 1:30 3plD3.The studyof individualdifferences in theauditory system. Dennis McFadden (Dept. of Psych.,Mezes Hall 330,Univ. of Texas, Austin, TX 78712) Individualpeople often produce reliably different results on variousauditory tests even when all havenominally normal hearing. An emergingtopic in hearingresearch isthe origins of theseindividual differences in normal-hearing people. Examples of procedures usedto ]neasurethe potential contribution of genetics and hormone exposure to individualdifferences will bediscussed, and several examplesof a specialinstance of individualdifferences in hearing-sex differences-will be described.Of considerablevalue for the ultimateunderstanding of individual differences are situations in whichsubsets of peoplediffer in a similarway across different auditorymeasures because covariations of this sort have the potential to revealcommon underlying mechanisms. WEDNESDAY AFTERNOON, 15 MAY 1996 MT. RUSHMORE, 1:00 TO 3:15 P.M. Session3pPA PhysicalAcoustics and Bioresponse toVibration and to Ultrasound: Workshop on Therapeutic Applications of Medical Ultrasound IV: Tour to Indiana University Schoolof Medicine Robert E. Apfel, Chair YaleUniversity, New Haven, Connecticut06520-8286 Registrationforthis tour will beconducted at session 2pPAa on Tuesday afternoon in Regency C. Spaceis limited. Invited Paper 1:00 3pPA1.Shock wave lithotripsy: A demonstration of experimental methods for in vitroshock wave exposure and analysis of cellinjury. JamesA. McAteer,Sharon P. Andreoil,Andrew P. Evan,Dax D. Denman,Coleen Mallett (Depts.Anatomy and Pediatrics,Indiana Univ. Med. School, Indianapolis, IN 46202), Robin O. Cleveland,Michalakis A. Averkiou,Lawrence A. Crum (Univ.of Washington, Seattle, WA 98105), James E. Lingeman,and David Lifshitz (Methodist Hospital of Indiana,Indianapolis, IN 46202) Thislaboratory is involved in studiesto determinethe mechanism(s) responsible forcellular injury to thekidney during shock wavelithotripsy for the treatment of upper urinary tract stones. The studies are performed using an electrohydraulic lithotripter (DomletHM3) and injury to isolated, cultured renal tubular epithelial cells was assessed. In this demonstration ourexperiences with thepractical aspects ofperforming invitro SW exposures areshared. Issues tobe discussed and/or demonstrated include the following: (a)choice of culturedcell models and the handling of isolatedcells, (b) factors that influence in vitro cell injury, (c) selection and preparationofspecimen vials, (d) lithotripter setup and operation, (e)positioning thespecimen andcontrol ofexposure parameters, (f) electrodeperformance andvariability, (g)characterization ofwaveforms anddetermination ofSW pressures, (h)markers ofcell injury andcell response toSW insult, and (i) safetyin the lithotripsy suite. [Work supported byNIH Program Project Grant No. POi 43881: Roleof SWL in renalinjury and stone comminution.] 2527 J. Acoust.Soc. Am., Vol. 99, No.4, Pt.2, April1996 131stMeeting: Acoustical Society of America 2527 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, 15 MAY 1996 CELEBRATION A, 12:30 TO 2:00 P.M. Session3pSA Structural Acousticsand Vibration: Fuzzy Structures GeoffreyL. Main, Chair Officeof Naval Research,Code 334, 800 North QuincyStreet, Arlington, Virginia 22217 ContributedPapers 12:30 only in a statisticalsense. The goalof the fuzzy theoryis to modelcomplex structureswith as few parametersas possible.The researchpresented here 3pSAI, Numerical solutionsof a prototypicalmaster structure/fuzzy is an experimentalinvestigation of the effectivenessof fuzzy parameter substructuresystem. RichardL. Weaver (Dept. of Theoreticaland choicesin modelingthe drive-point impedance of a beamwith a numberof Appl. Mechanics,216 TalbotLab., Univ. of Illinois, 104 S. Wright St., simpleoscillators attached along its length.The fuzzy modelmakes use of Urbana,IL 61801) "mostlikely" distributionsof massper unit resonancefrequency, given The transientresponse of a singledegree of freedommaster oscillator limitedknowledge about the attachedoscillators. The oscillatorsare inter- attachedto a simpleundamped N degreeof freedom"fuzzy substructure" changedin orderto achievevarious realizations of massper unit natural is studiednumerically and theoretically. Results at earlytimes are found to frequency.The magnitudeand phase of the measuredcldve point imped- be in accordwith the predictions of thePierce-Sparrow-Russell theory; in anceare compared to thatpredicted by fuzzytheory models. The useof the particular,the masteroscillation manifests an apparentdamping. At later momentsof the massper unitnatural frequency distribution as the primary times,however, the energyis returnedfrom fuzzy to master.The precise descriptorsof the effectof the fuzzy substructuresis examined. Bounds on mannerin which the energyis returnedand the time taken to do this the differencesherween predicted and measureddrive point impedanees dependon the detailsof the massand frequencydistribution within the are established.The use of thesebounds in applicationssuch as high- fuzzy and, in particular,on the distributionof spacingsbetween the fuzzy performance,robust vibration control is discussed. resonances.For the caseof irregularlypositioned fuzzy resonancesthe energyreturns immediately and the masterthen oscillates randomly. For the caseof regularlyspaced fuzzy resonancesthe energyreturns after a longertime, and doesso coherently.Theory is presentedwhich supports the accuracyof the Pierce-Sparrow-Russellresult at short times. Other 1:15 arguments(for the caseof randomfuzzy resonances)predict the root4 3pSA4. Vibration responsestatistics in regular and irregular plates. mean-squarelevel of the subsequentrandom oscillations. Still others(for ChristopherA. Harteminkand RichardG. DeJong (Eng. Dept., Calvin the caseof regularlyspaced fuzzy resonances)predict the returntime. College,Grand Rapids, MI 49546) [Worksupported by ONR.] Statisticalmeasures of the vibrationresponse of flat platesin boththe 12:4• frequencyand spatialdomains are presented.Analytical, numerical, and experimentalresults are presentedfor rectangularand irregularlyshaped 3pSA2. Equipment representationsas time-domainfuzzy structures. plates.The resultsare consistentwith the assumptionthat the modalre- AravindCherukuri and Paul E. Barbone (Dept.of Aerospace& Mech. sponseof a rectangularplate is sinusoidal,while the modal response of an Eng., BostonUniv., I l0 CummingtonAve., Boston,MA 02215) irregularlyshaped plate is Gaussian.The statisticalmeasures of a plate vibrationresponse can be usedto evaluatethe system modal overlap factor, The presenceof complexsubsystems can dramaticallyaffect the dy- theratio of themodal damping bandwidth to themodal frequency spacing. namicsof the mainstructure to whichthey areattached. Exactly modeling thesesubsystems, however, is oftenimpossible. Here, replacingthe sub- structure(say a pieceof equipment)by an equivalentset of forceswhich react back on the main structureis proposed.These forcesare given as time convolutionsof the displacementsat the equipmentattachment 1:30 points. The convolutionintegral, which representsa time-domainDtN (Dirichlet-to-Neumann)map, is approximatedin the high modaldensity 3pSAS.Development of a mid-frequencydefinition and appropriate limit with determinederror bounds. Local in time approximationsto the analysistechniques. JohnE. Huff, Jr. (Schoolof Mech. Eng., Purdue convolutionintegral are obtained using Pad6 approximants. These yield a Univ., 1077 HerrickLabs., West Lafayette, IN 47907-1077),Guglielmo family of equipmentrepresentations. The simplestrequires two measured Rabbioio,Robert J. Bernhard,and FabioA. Milner (PurdueUniv., West equipmentproperties, though more information can lead to greateraccu- Lafayette,IN 47907) racy. Our approximateDtNs are validatednumerically in finite-element simulations.[Work supported by ONR.] From experimentaldata collectedon ensemblesand from analytical verificationstudies of s•-ucturalacoustic systems, it is apparentthat there is a nfid-frequencyrange wheredominant structural acoustic responses 1:00 cannotbe sufficientlydescribed deterministieaily or statistically.The focus 3pSA3. Experimental identificationof fuzzy structure parameters. of this presentationis to describework to derivea generaland rigorous RaymondJ. Nagera,Ann W. Stokes,and Allan D. Pierce (Dept. of definitionfor the frequencylimits of the mid-frequencyrange. The statis- Aerospaceand Mech. Eng., Boston,Univ., 110 CummingtonSt., Boston, ticalbehavior of systemresponse in thisrange is describedthrough the MA 02215) analysisof the analyticalexpressions for thedisplacement of Bemou!li- Eulerbeams. Additionally, work to developa numericalanalysis technique Researchershave recently been developing a theoryto modelstruc- whichcan be implementedin a finiteelement formulation is discussedand turesin which a primaryor "master"structure with preciselyknown thepossible connections between it and current techniques for energy flow parametersis coupledto "fuzzy" substructureswith parametersknown analysisin the high-frequencyrange are made. 2528 d. Acoust.Soc. Am., Vol. 99, No.4, Pt. 2, April1996 131stMeeting: Acoustical Society of Amedca 2528 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 tionsin perfectlytuned nonlinear systems. Recent work by the authorhas investigatedthe combinedinfluences of weak nonlinearitiesand weak 3pSA6. Forced localization in mistuned nonlinear repetitive structuralmistunings in generatinglocalized modes. In the presentwork, structures. Melvin E. King (Dept. of Aerosp.and Mech. Eng., Boston thefomed response of nonlinearcyclic systems with structuralmistunings Univ., Boston,MA 02215) is investigatedvia the methodof multiplescales. Under harmonic excita- tions,strongly and weaklylocalized motions will be shownto existfor The presenceof localizedmodes in repetitivestructures (i.e., systems variousstructural parameters. Sample calculations will be presentedfor composedof identicalsubstructural elements) often gives rise to motions systemscomposed of two, three,and four degrees of freedom.Addition- duringwhich vibrational energy becomes spatially confined to a subsetof ally,motion confinement characteristics of such systems will be demon- elements. Such modes have been shown to be generated through stratedfor transientloading conditions, and the implicationsfor novel eignevalueveering in weaklymistuned linear systems and modebifurca- vibrationisolation designs will be discussed. WEDNESDAY AFTERNOON, 15 MAY 1996 CIRCLE THEATER, 3:15 TO 5:15 P.M. Plenary Session,Business Meeting, and Awards Ceremony RobertE. Apfel, Chair President,Acoustical Society of America BusinessMeeting Vote on changesto ASA Certificateof Incorporation Announcementof Gold and Silver CertificateRecipients Presentation of Certificates to New Fellows Presentation of Awards Gold Medal to Ira Dyer R. BruceLindsay Award to Victor W. Sparrow Presentationof President'sTuning Fork Presidential Address "Acoustics in 2016" NOTE: The TownMeeting will immediatelyfollow the Plenary Session at theCircle Theater. 2529 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2529 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, 16 MAY 1996 MT. RUSHMORE, 9:00 TO 11:25 A.M. Session 4aAA Architectural Acoustics:Design and Measurement in Architectural Acoustics Dana S. Hougland,Chair David L. Adams Associates, Inc., 1701 Boulder Street, Denver, Colorado 80211 Chair's Introduction--9:00 ContributedPapers 9:10 equivalentto testing three standardrooms, but the testsdid not include variationsdue to differenttypes and placementsof transducers.The vari- 4aAAI. A musical history of architectural acoustics. Christopher ous measurementswere madeover a one year periodand the reverberator Herr and Gary W. Siebein (ArchitectureTechnol. Res. Ctr., 231 ARCH, andmeasurements were shown to be stableand very reproducible over this Univ. of Florida,P.O. Box 115702,Gainesville, FL 32611-5702) period.The meansof the closelyclustering results were used to represent A briefmultimedia presentation explaining the mutual developments of the best estimate of the "correct" answers. The standard deviations of the acoustics,music, and architecture was developed to illustratethe relations closelyclustering results were usedto evaluatethe divergenceof the mea- amongart, science,culture, and musicin the evolutionof westernarchi- surementsfromthe central trend. Approximately -•of the results were tecture.Throughout much of the history of the westernworld there has within two of thesestandard deviations from thecentral trend. Two specific beena clearlydiscernible connection between the developmentof music, problemswere identifiedand solutionsrecommended. While most results musicalinstruments, ensembles, and the designof spacesfor musicalper- werein closeagreement, a numberof resultsdiffered significantly from the formances.This multimediapresentation was developedto illustratethe central trend and demonstratedthe importanceof validating new room creativepotential of understandingmusic and acousticsin the historyof acousticsmeasurement systems. architecture.The acousticalrationales for musical and architecturalphe- nomenaare studiedin the contextof composersand musicalworks. The 9:55 musicalpieces have beencouvoived with the acousticalproperties of the spacesin which they were originallyperformed to allow peopleto aurally 4aAA4. Automated architectural acoustical modeling with the experiencea simulatedacoustical history of architecture.Examples studied SeDReSsystem. Gary W. Siebein,Mitchel E. Spolan,and Christopher include chantsin large cathedrals;Gabrieli's music composedfor St. Herr (ArchitectureTechnol. Res. Ctr., 231 ARCH, Univ. of Florida, P.O. Mark's; comparisonsof Haydn'sworks written early in hiscareer for small Box I i 5702, Gainesville,FL 32611-5702) orchestrasin small rooms and those written later in his career for larger orchestrasin larger rooms; the operaticworks of Wagner and the unique A computer-controllodarchitectural modeling system was developed to environmentat Bayreuth;and the explorationof tone color and experi- allow the enclosureand materialsof a room to he rapidlyand precisely mentalmusic and architecturein the 20th centuryamong others [Work varied for acousticaltesting using ultrasonic sparks and miniaturemicro- supportedby NSF.] phonesat variousscales (depending upon the sizeof the modelroom to be tested).A systemof steppermotors moves segmented wall, ceiling,and floorpanels of a large,flexible enclosure. The walls,ceiling, and floorcan be movedto configurea wide varietyof roomsfrom a small lectureroom 9:25 to a largearena. The locationsand anglesof the enclosingsurfaces of the roomfor multipledesign motifs can be storedin the memoryof the com- 4aAA2. The duality of the observer and the observed--From puter.One can thenpush several keystrokes to reconfigurethe roomand quantum mechanics to architectural acoustics. Robert T. Beyer proceedwith acousticaltesting and simulationusing the acousticalre- (Dept. of Phys.,Brown Univ., P.O.Box 1843,Providence, RI 01912) searchinstrumentation for architecturalspaces {ARIAS} system.Impulse In 1928, Niels Bohr pointed out the dual descriptionrequired in the responses,acoustical measurements, and aural simulationsfrom alternative quantummechanics of measurement,involving the observerand the ob- designscan be comparedat the earlieststages of the designprocess when served[Natunvissenschaften 17, 483-486 (1928)], and a few yearslater, one is consideringbasic choices of finishmaterials, room shape.and wall John yon Neumanndiscussed this principleat some length in his text on angles.[Work supported by NSF.] the MathematicalFoundations of QuantumMechanics [(Springer-Verlag, Berlin,1932), English translation. Princeton U.P., 1955].It nowappears that architecturalacoustics has been following the sameroute. Examples 10:10 cited by yon Neumannare describedand paralleledwith examplesfrom 4aAAS. Analysis and synthesis of room reverberation in the time the work of Schroeder,Ando, and others in concert hall acoustics. and frequency domains•Application to the restoration of room impulse responsescorrupted by measurementnoise. Jean-Marclot, GuillaumeVandernoot, and Olivier Wamsfel (IRCAM, 1 PI. Stravinsky, 9:40 75004 Paris,France) 4aAA3. Comparisonsof room acousticsmeasurement systems. J.S. This paperreviews a statisticaltime-frequency model of the late dif- Bradley (Acoust. Lab., Natl. Res. Council, Ottawa, ON K1A 0R6, fusereverberation in rooms.In thismodel, the later part of a roomimpulse Canada) responseis describedby a "time-frequencyenvelope," defined as the ensembleaverage of the time-frequencyenergy distribution in the late This paper gives a summaryof the results ot' an internationalroom decay.The time-frequencyenvelope is independentof the sourceand re- acousticsmeasurement system round robin. Twenty-threedifferent mea- ceiverlocations and is characterizedby two functionsof frequency:the surementsystems were comparedby measuringthree settingsof the same reverberationtime anda powerspectral density called the "initialspec- digitalreverberator that was shipped to eachmeasurement group. This was trum," whichcorresponds to the productof the diffuse-fieldtransfer func- 2530 J. Acoust.Soc. Am., VoL99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2530 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 tionsof the sourceand the receiver.An analysismethod is describedfor ration,the authorsundertook a studyof the feasibilityof renovatingand derivingthese paramelers from a measuredimpulse response, yielding an improvingThe Great Hall while maintainingthe architectonicintegrity of accurateestimate of the reverberationtime with arbitraryresolution in the the space,as necessitatedby historicallandmark protection. It was found frequencydomain. The time-frequencyenvelope defines a time-dependent that a simplereplastering of the walls and ceiling of the auditoriumwill filter which transformsa sampledstationary Gaussian white noiseinto a lower the reverberation time at 250 Hz from over 3 s to under I s and syntheticmodel of the late reverberationdecay. Substituting this synthetic shouldsignificantly reduce the effect of late (after50 ms) reflections.The reverberationdecay to thepart of an impulseresponse that is corruptedby newplaster will havelower density and higher porosity than the old plas- measurednoise. yields a restoredimpulse response allowing faithful au- ter, significantlyimproving its sound-absorbingcharacteristics. The pro- ralizationby convolutionwith anechoicsource signals. The modelsand the posedrenovations are currentlyunder consideration for implementation. methodsdescribed are illustratedon impulseresponses measured in a concert hall. 10:55 4aAAS. Comparative study of modular and standard construction 10:25 methods for broadcast/recording studio applications. David Michalek and BrandonTinianow (AcousticSystems, P.O. Box 3610, 4aAA6. Analysis of subjective acoustic measures and speech Austin, TX 78764) intelligibility in Portuguese churches. Ant6nio P.O. Carvalho. Ant6nioMorgado (Acoust.Lab., Dept. of Civil Eng.,College of Eng.. Consultantsand owners are becomingincreasingly aware of the choice Univ. of Porto, R. Bragas,4099 Porto Codex, Portugal),and Lugs betweenmodular versus conventional construction methods when design- Henrique (Schoolof Music-ESMAE,4000 Porto,Portugal) ing or remodelingbroadcast and recording•tudios. In a laboratoryenvi- ronmentthe physicalattributes such as acousticisolation, direct material This •tudy report•on subjectiveacoustical field measurementsmade in costs,physical weight, etc. havebeen quantified and the resultingcost per a surveyof 36 Catholicchurches in Portugalbuilt in the last 14 centuries. dB of attenuationdetermined. When assessing the methodto be employed, The samegroup of collegestudents were askedto judge the qualityof the lessobvious yet vital differencesoften overlooked include the consult- speechand musicat all the churches.Two setsof listenersin eachchurch ants' added liability associatedwith conventionalconstruction methods evaluatedlive musicperformance (cello and oboe) at two similarlocations (riskof failureof acousticalisolation), supervision required during con- in eachof therooms using a seven-pointsemantic differential rating scale. An acoustical evaluation sheet was used to measure listeners overall im- structionto insureattention to criticalsound isolation details. durability, installationtime, shortage of qualifiedworkmen, fit andfinish, exposure to pressionof room acousticsqualities, and each of the factorsthat can unexpectedon-site delays, ability to retrofit,or relocate,etc, These design contributeto thatperception as loudness,reverberance, intimacy, envelop- and costconsiderations will be comparedand contrasted. ment,balance. elario', echoes, and background noise. Speech intelligibility testswere also given to thesame group in eachchurch. One-hundred-word 11:10 lists were usedin live speechtests using a theatercollege student as speaker.The resultsare graphedand analyzedby comparisons.Variations 4aAA9. The effects of special coatingson the Sabine-Guastavino of subjectiveand speech intelligibility qualities were identified among the Rumford acoustical tiles. Richard Pounds (Graduate School of different churches and within each of the churches as well. For instance, Architecture,Planning and Preservation,Columbia Univ., New York, NY churchmean values for the intelligibilityscores range from 56% to 96% 10027), Daniel R. Raicbel (CooperUnion, New York, NY 10003 and correctwords and the variabilitywithin eachroom extentfrom 6% to 49%. CUNY), andMartin Weaver (ColumbiaUniv., New York, NY 10027) The subjectivequalities that contributed to overallacoustical impression were also identified.[Work supportedby CEDEC. ESMAE and UP- WallaceC. Sabineand RafaelGua•tavioo developed the Rumfordtiles Portugal.] specificallyto lessenthe reverberationtimes insideecclesiastical edifices. These tiles are usedin a numberof churches,including St. Bartholomew and St. Thomas,both in New York City, and the Duke UniversityChapel 10:40 in Durham.NC. In recenttimes. those responsible for musicalprograms 4aAA7. A proposedacoustical renovation for The Great Hall at The have been demandinggreater reverberation times, even at the expenseof CooperUnion. GregoryA. Miller (Dept. of Mech. Eng., The Cooper clarityof spokenwords. Accordingly sealers are being applied to a number of church interiors in order to increase the reverberation times. Because of Union. 51 Astor PI.. New York, NY 10003} and Daniel Raichel (The CooperUnion and CUNY, New York, NY 10003} the limited samplesavailable, the toneburst method was appliedat the CooperUnion Acoustics Research Center to measurethe effect of applying The Great Hall is an l100-seat auditorium with historical landmark specialcoatings to decreasesound absorption coefficients. The absorption statusbuilt in 1859. It has been the site of many historicspeeches by coefficientswere measured for the nakedtiles, provided by the FirstCon- figuresranging from PresidentAbraham Lincoln to Sioux Chief Red gregationalChurch of Montclair, NJ, and after the consolidatorwas Cloud.Throughout its history, however, The GreatHall hasbeen described sprayedon. The test was also repeatedfor each applicationof the sealer. as a lessthan adequate acoustical environment, suffering from low speech The resultsof the testindicate that a considerableamount of coatingwill intelligibilityand excessive reverberance. Building upon the previouswork be necessaryto decreasethe soundabsorption coefficient to the proper of Raicheland Dragan who modeledthe auditoriumin its currentconfigu- degree. 2531 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society of America 2531 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, 16 MAY 1996 CANYON HALL, 8:00 TO 11:50 A.M. Session 4aAB Animal Bioacoustics:Intra-Specific Variations in Animal VocalizationsI Robert H. Benson, Chair Centerfor Bioacoustics,MS 3367, TexasA&M Universi.ty,College Station, Texas 77843-3367 Chair's Introduction---8:00 Invited Papers 8:05 4aAB1.Song displays, song dialects, and lek matingsystems in hummingbirds.S.L.L. Gaunt (BorrorLab. Bioacoustics, Dept. Zool, Ohio State Univ., Columbus, OH 43210) Malesof somehummingbirds, including Colibri (violet-ears), congregate and display from traditional areas, !eks, to attractmates. Hummingbirdsuse a vocaldisplay. Males on a lek sharethe samesong, i.e., nearestneighbors share song; males on distant, acousticallyisolated, leks have different songs. i.e., thereare dialects. Dialects have been used as evidence for songlearning in birds, and,although song learning is usuallyascribed to oscinesand parrots, hummingbirds share vocal organ (syrinx) structures with them consistentwith songlearning ability. Digital spectrogram cross correlation was used to objectivelydetermine degree of songsimilarity; thisstatistic was used in clusteranalysis to describerelationships between birds and with the Mantel methodto testhypotheses about associations.Further, males of a iek delivertheir song cooperatively, i.e., withoutinterference. The resultantis a lek signalthat, from a distance,sounds as one song. If, asin othercooperative lekking systems. there is a skewin benefits,i.e., few obtainmates, then other malesmay gain benefits indirectly through relatedness (kin selection).Results from preliminary, DNA "fingerprinting"do notsupport thishypothesis, and alternative explanations are suggested. [Work supported, in part,by NSF.] 8:35 4aAB2.Recognition of the utterancesof terrestrialwildlife: A newapproach. RonaldP. Larkin (IllinoisNatural History Survey, 607 E. PeabodyDr., Champaign,IL 61820),Daniel Margoliash, Joseph A. Kogan (Univ.of Chicago),and Larry L. Pater (USArmy CER•) Findingand eensusingbirds and otheranimals via listeningcan poseproblems because of inaccessibilityof habitats,rarity or shyneTsof animals,or subjectivityof observers.A newcollabomtive project seeks to evaluatealgorithms adapted from human speech recognitionto establisha basisfor automatingthe identificationof animalvocalizations and recording their occurrence. The algorithms includedynmnic time warpingand hybrid hidden Markov models incorporating features of artificialneural networks. Probably no singlemethod will work for all species.More thanone methodmaybe useful together, in multiplestages. A databaseof high-quality, annotateddigital field recordingsis beingcollected to supplytraining and test data on known speciesand, when possible,known individuals.Both low-noiseand realisticambient noise situations are important.Field data are supplementedwith recordingsfrom laboratorysettings. Red-cockaded woodpecker, other vocal yet threatenedspecies, and species related to them,such as otherPicoides woodpeckers,are being studied. Preliminary results are presented. [Research supported by USACERL.] 9:05 4aAB3. Intraspecificvariation in primate vocalizations. leffrey C. Norris (Ctr. for Bioacoustics,Texas A&M Univ., 5007 Ave. U, Galveston,TX 77551) lntraspecificvariability in primatevocalizations exists at severallevels--within organizationallevels of a species,as well as differinglyacross acoustic variables. This paperreviews signal variability between subspecies, groups and populations,individuals, and within a singleindividual's vocalizations. The problemof signalvariability is best seenwhen humansdescribe a species' repertoire.The literatureis repletewith exampleswhere humans underestimate the amountof variabilityrecognized by the animals; humanstypically are lumpers,where playback experiments show that the animalsrecognize differences that are imperceptibleto us. The perceptualcues used by five primatespecies will havebeen described. Sensitivity to variabilityis not uniformbetween acoustic variables.Variability in signalproduction has been described for an additional14 species.Details of interindividualand intraindividual variabilityof wedge-cappedcapuchin alarm calls is described.Where early taxonomiesof thisspecies' vocalizations recognized two alarmcalls, subsequent research by theauthor described 15 variantsof onecall, at leastthree of whichwere recognized by themonkeys to referto different objects. The importance of thevocalization's function will bestressed, recognizing that motivational calls may have greaterintrinsic variability than those referring to specificexternal objects. 9:35-9:50 Break 2532 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2532 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 Contributed Papers 9:50 may haveoccurred during the season.Alternatively, whales may be pre- disposedto graduallychange features of song independentof cultura• 4aAB4. Sperm whale codas in the northwesternGulf of Mexico. influences.Given the low levelof variabilityexhibited by manyvariables, Troy D. Sparks,William E. Evans (Marine Acoust. Lab., Ctr. for the latter seemsmore likely; therefore,temporal change. like songstruc- Bioacoustics,Texas A&M Univ., 5007 Ave. U, Galveston,TX 77551 ), and ture, may be governedby a disereleset of rules.Further research on a RobertH. Benson (TexasA&M Univ., CollegeStation, TX 77843-3367} longer time scale is needed. Spermwhale (Physeter macrocephalus) coda patterns from the north- westernGulf of Mexico have beenexamined. Recordings were collected 10:35 via a towedpassive hydrophone array. Sperm whales are knownto produce a characteristic"hammering" click. Codasare rhythmicpatterns of clicks 4aAB7. The use of passive sonar to detect sound production and [W. A. Watkinsand W. E. Schevill,J. Acoust.Sec. Am. 62, 1485-1490 calculate population densities of penacid shrimp in the Gulf of (1977)].Two types of codashave been proposed: identity codas and gen- Mexico. lions M. Berk, William E. Evans (Ctr. for Bioacoustics,Marine eraluse or sharedcodas [Watkins et al., Cetology49, 1-15 0985)]. Iden- Acoust. Lab., Texas A&M Univ., 5007 Ave. U, Galveston,TX 77551), tity codasare patternsthat are uniqueto an individualfor at leasta few RobertH. Benson,and MichaelE. Duncan (TexasA&M Univ., College hours, and general use codas are vocalizationsthat seem to be shared Station,TX) among groupsof whales. In the southeastCaribbean, it was found that Past researchconcluded that nonstridulatingpink shrimp(Penaeus 50% of the codasanalyzed were madeup of two patterns;therefore, it was duorerum) found in the Gulf of Mexico did not make sound in the sonic proposedthat sharedcodas may have a function other than individual identity[Moore et al., Mar.Main. Sci. 9, I-9 (1993)].There also appears range,but might produceultrasonic sound via friction betweenparts of the to be geographicaldifferences in codas'spacing and composition between exoskeleton[W. R. Gehring,Sea Grant Bulletin #5 (1971)].Recordings of theGalapages and the southeast Caribbean [L. Weilgartand H. Whitehead, "frying" noisesover known penacidshrimp beds led to speculationthat Can.J. Zoo. 71,774-752 (1992)]. the shrimpwere mechanicallyproducing the "frying" portionof the am- bient noise,and that passivesonar might be usedas a tool for penacid shrimpdetection and estimationof populationdensities [W. E. Evans, 10:05 AcousticsSignature Catalog, 82-141 (1982}].Sound production by non- stridulatingwhite shrimp (Penaeus setiferus) of theGulf of Mexicowas 4aAB5. A comparisonof the songsof the tufted and black-crested studiedusing passive sonar. Video and hydrophonerecordings were made titmice. Cadc L. Coldten (Dept. of Wildlife and FisheriesSciences, of captiveshrimp populations with knowndensities. Hydrophone record- TexasA&M Univ., CollegeStation, TX 77832-2258) ingsof wild populationswere made pre- andpostshrimp trawls, and trawl The songsof the Easterntufted titmouse(Parus B. bicolor) and the catchdata were noted.Results showed that the captiveshrimp produced black-crestedtitmouse (Pants B. sennertl)were examinedas a possible detectablemechanical sound primarily via escapemovements and possibly systematictool. From nine sites,65 songtypes were identified,falling into mastication.Initial comparisonsuggests that wild shrimp and captive four categories:one-note phrase, two-note long-short phrase, two-note shrimpsounds are similar.It is hopedthat the final resultsof analysiswill short-longphrase, and three-notephrase songs. Canonical discriminant confirmthat wild penacidshrimp population density calculations are fea- analysison morphometricparameters revealed greater variation in song sible usingpassive sonar data. between sites than within sites. Black-crestedtitmice typically sing at higherdominant frequencies, shorter phrase durations, a highernumber of 10:50 phrasesper song, and a smaller repertoirethan luffed titmice. Black- crestedrepertoires were composedmostly of one-holephrase songs and a 4aAB8. The acousticsof snapping shrimp in Kaneohe Ba.•; Whirlow few two-notephrase songs. Tufted titmice repertoires had approximately W. L. Au (Hawaii Inst. of Marine Biology,P.O. Box 1106,Kailua, HI equalproportions of one-noteand two-notephrase songs with one three- 96734) and Kiara Banks (Florida Inst. of Technol.,Melbourne, FL 32901) note phrasesong at each site. Differencesin body size and habitatdensity may explainthe higherdominant frequencies found at black-cre•tedsites. Snappingshrimp are amongthe majorcontributors of biologicalnoise The possibleoccurrence of dialectsand the role of learningmay account in shallowbays. harbors, and inletslocated in temperateand tropicalwa- for all differencesin song.However, their impactson titmicesongs must ters. Snappingshrimp •ounds can severelylimit the use of underwater be determinedbefore song can be usedas a reliablesystematic tool for the acousticsby humansand other animalssuch as dolphins,whales, and tuftedtitmouse complex. pinnepeds.They produce sounds by rapidlyclosing their frontal chela, or claws,snapping the two endstogether to generatea loudclick. The acous- ticsof the speciesSynalpheus paraneomeris was studied by measuringthe 10:20 soundproduced by individualshrimp housed in a smallcage located I m 4aAB6. Geographic variation and cultural evolution in songs of from an H-52 broadbandhydrophone. Ten clicksfrom 40 specimenswere humpbackwhales (Megapteranovaeangliae) in the eastern North digitizedat a I-MHz samplerate and the data storedon disk. Various Pacific. SalvatoreCerchio (Museumof Zoology,Univ. of Michigan, acousticparameters such as sourcelevel, spectral content, and center fre- 1109 GeddesAve., Ann Arbor, MI 48109) and Jeff Jacobsen (P.O. Box quencywere correlatedwith claw size and body length.Peak-top-peak 4492, Arcata. CA 95521) sourcelevels varied from 183 to 189dB re: 1 /•Pa. A typicalspectrum had a low-frequencypeak between 2 and 5 kHz and energyextending out to Songsof humpbackwhales off Hawaii and Mexico were examinedto 200 kHz. determinewhether they changedsimilarly in both areasduring a breeding season.Songs of 24 individualswere recordedoff Kauai,Hawaii and Isla Socorro,Mexico during winter and springof 1991. Forty-sevenacoustic 11:05 variablesdescribing all levelsof songstructure were measuredfor each 4nAB9. Intraspecific variation in the vocalizationsof the wilier singer.Similar variables were grouped together into six categories.Mean Catoptrophorussemipalmatus. Hector D. Douglas (Dept.of Biology, valuesfor eachsinger were comparedamong regions and time periods Wake Forest Univ., P.O. Box 7325, ReynoldaSt., Winston-Salem,NC usingtwo-factor ANOVAs. All butthree variables changed between winter 27106) and springin at leastone area. Groupsof similar variablesdisplayed similar trends.Quantitative characteristics of songelements often changed The acousticalrepertoire of the easternwillet was recordedat sites duringthe breedingseason by the sameamount in eacharea, with little alongthe Atlanticseaboard using a Marantzportable cassette recording variationwithin and amongindividuals. Structures of songpatterns often deck (modelPMD 220, a Sennheisermicrophone (model K3-U), and a changeddifferently in each area. Resultsindicated cultural transmission 62-cm fiberglassparabolic recording dish. Associated behaviors were an- 2533 d. Acoust.Sec. Am., Vol. 99, No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society of America 2533 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 notatedon audiotape and in field notebooks.Call parameterswere mea- tinctlydifferent vocalizations in the Atlanticand Pacific;but like finbacks, suredusing a DSP Sona-Graphmodel 5500. Variationin call parameters both Atlantic and Pacific whales have two principal call types, with dif- wasassessed within individuals, within populations, between geographical ferentmixtures of the typesin differentareas. Differences in timingand regions,and betweensubspecies using cross correlations and univariate frequencyare heardin distinctaxeas, with certainpatterns heard only in and multivariatestatistical methods. Sohograms, preliminary quantitative oneor a few areas.[Work supported by ONR.] resultsand aural comparisons suggest relatively litfie structuralvariation in callsacross large geographical regions. One notable exception in thispat- 11:35 tern was observedat the subspeelfie level, and a hypothesisis advanced linkingdifferences in ecologyand environmentalfeatures to explainthis 4aABll. Objective analysis of song learning in birds: Toward divergence.Some intraindividual variation could be linkedto hypothesized automatedtechniques. S.E. Anderson,C. A. Staieer,S. Inoue,and D. transitionsin motivationalstates as indicatedby incidentalchanges in Margoliash (Dept. of OrganismalBiology and Anatomy,Univ. of behavior.Results suggest that vocal developmentin the wilier is based Chicago,1025 E. 57thSt., Chicago,IL 60637) upon innate templates.However, observations also suggestthat these It is demonstratedthat indigobuntings sing boutsof "adult plastic" formsmay be recombinedto encodedifferent information. songs(APS) distinctfrom stereotypedsongs (SS). Somedistinguishing characteristicsof APS include syllablesof variable morphologyand syl- 11:20 lablesnot presentin SS.The hypothesisthat APS mayplay a role in adult songlearning is testedby monitoringsocially paired males housed to- 4aAB10. Geographicand seasonalvariation in blue and finback gether.Some yearlings changed their SS to moreclosely match their tutors' whale voealizations.David K. Mellinger (BioacousticsRes. Program, SS, by replacingsyllables or insertingnew syllables. New syllableswere Cornell Univ., 159 SapsuckerWoods Rd., Ithaca, NY 14850) and developedin APS throughtransformation and combination of morphologi- ChristopherW. Clark (CornellUniv., Ithaca, NY 14850) cally similarexisting syllables, and syllableswere transferred from APS The U.S. Navy maintainsa networkof listeningarrays for detectionof into SS. To addressthe limitationsof manualscoring of spectrographs, submarines.}:or several years, some of the soundsfrom thesearrays have dynamictime warping(DTW) for template-basedautomated analysis of been made available to scientistsfor study of cetaceanmovements and continuousrecordings of birdsongswas evaluated. With laboratoryrecord- vocalizations.Here the vocalbehavior of blue (Balaenopterarnusculus) ings,the DTW algorithmemployed identified syllables and syllable bound- andfinback (B. physalus)whales are analyzed. These species produce long ariesof SS and calls of indigo buntingand zebra finch with greaterthan sequencesof calls,lasting hours to days,that exhibit several types varia- 97% accuracy.APS constituentswere identifiedwith approximately84% tion acrossareas of the North Atlantic and Pacific. Finback producetwo accuracy.Under theserestricted recording conditions, DTW has general commonlyheard general types of calls,with othertypes present less fre- applicabilityto objectiveanalysis of birdsongs,and dramatically decreases quently.Finbacks in differentgeographic areas exhibit variations in fre- the effort required.Application of hybrid hidden Markov models may quency,in intercalltiming, in themixture of calltypes, in patternsof calls improvethe performancefor variablevocalizations such as APS, andun- and silences,and in otherways. Blue whales,unlike finbacks,show dis- der noisyconditions of field recordings. THURSDAY MORNING, 16 MAY 1996 NATIONAL PARKS, 8:00 TO 11:45 A.M. Session 4aEA EngineeringAcoustics: General EngineeringAcoustics Alison B. Flatau, Cochair AerospaceEngineering and EngineeringMechanics, Iowa StateUniversity, 2019 BlackEngineering Building, Ames, Iowa 50011 Frederick T Calkins, Cochair AerospaceEngineering and EngineeringMechanics, Iowa State University,2019 Black EngineeringBuilding, Ames, Iowa 50011 ContributedPapers 8:00 frequencyand to determinethe corresponding group velocity. These modes are then identifiedby comparingthe resultswith predictionsfrom theo- 4aEAI. Mode control of ultrasonicguided wavesin thick cylinders retical dispersioncurves. One can then predict the energy distribution for crack detection. ZongbaoLi and Yves H. Berthelot (School of within the structureby using the methodof normal mode expansionfor Mech.Eng., Georgia Inst. of Technol.,Atlanta, GA 303320405) transients.[Work supported by the ONR, Code332.] Experimentson ultrasonicpropagation in thick annularstructures show that one can simplifythe modalstructure of the receivedsignals by care- 8:15 fully controllingthe wedgeangles of the generationand detectiontrans- 4aEA2. Practical implications of micromachined ultrasonic ducers.This is importantif one is to detectcracks along the pathbetween transducers. Igal Ladabaumand Butms T. Khud-Yakub (Stanford sourceand receiver.In particular,one shouldexcite and detectonly those Univ., E. L. Ginzton Lab., Stanford,CA 94305) modeswhose energy is concentratedwhere the cracksare expectedto form. To do so, the following methodologyis used:First, experimental Micromachinedultrasonic transducers capable of airbornetransmission signalsare obtained for varioussource-receiver configurations with a stan- of 1- to 12-MHz ultrasoundhave been reported. It hasalso been reported dardpulser/receiver; a wavelet transform is thenapplied to the signalsto that thesetransducers should enable ultrasonic systems with 100 dB of localize preciselyin time the arrival of a given mode packet at a given dynamicrange. A justificationof the predicteddynamic range involves the 2534 J. Acoust. Soc. Am., Vol. 99, No. 4, lat. 2, April 1996 131st Meeting: Acoustical Society of America 2534 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 carefulconsideration of the thermal noise limits of thesystem. Such analy- haveshown that acousticpyrometry is easyto apply,accurate, and nonin- sis is developedand is basedon the fluctuationdissipation theorem. In vasive.Gas temperaturemeasurements are providedand displayedon a addition,the firstscans produced with the newtransducers are presented continuousreal-time basis for singlepath volumes in variousfurnace re- alongwith interpretationsof their significant impact to nondestructivetest- gionsand for multiplepath arraysin the furnaceexit gas plane. The ing. Picturesof surfaceand bulk defectsin compositesand metalsare determinationand presentation of isothermalmaps of gastemperature pro- included.Finally. the fabricationprocess is summarizedand the issues videa newtool for operationand maintenance diagnostics, not achievable involvedin the developmentof immersiontransducers are highlighted. by any othercurrently known method. Acoustic pyrometers are now being [Worksupported by the U.S. Officeof Naval Research.] usedto help identifyand correctburner problems, slagging problems. and furnaceoverheating before theseconditions can adverselyaffect opera- tions. 8:30 9:15 4sEA3. Modification of two methods for determining acoustic impedance. MichaelG. Jones (LockheedMartin Eng.and Sciences Co., 4aEA6. Comparisons of approximate and exact techniques for 144Res. Dr., Hampton,VA 23666)and Patricia E. Stiede (NASALangley conyactedacoustics. Laurine Leap (Cornput.Aided Eng. Dept., Ford Res.Ctr., Hampton,VA 23681) Res. Lab., Dearborn,MI 48121) and David R. Dowling (Univ. of Resultsof an investigationto modify two impedancemeasurement Michigan,Ann Arbor,MI 48109) methods(two-microphone method, TMM; and multipointmethod, MPM) In many aero- and environmental-acousticproblems, convection of to improveefficiency and convenienceare presented.The TMM is modi- soundwaves is handledby appropriatelyincreasing or decreasingthe local fiedby eliminatingthe need for oneof themicrophones in situationswhere speedof soundand then solvingthe resultingHelmholtz equation. Such only one microphonecan be placedinto the test environment.The MPM solutionsare typically obtainedvia integral transformsor geometrical modificationuses pseudorandom noise to significantlyreduce the time acoustics.An exactsolution technique that properly incorporates the vector necessaryto completeacoustic impedance measurements. These modifi- characterof mean-flowconvection has been found [L. Nijs andC. P. A. cationsare the resultsof on-goingtechnology development at NASA Lan- Wapenaar,J. Acoust.Soc. Am. 87, 1987-1998(1987)]. Unfortunately, the gley ResearchCenter to simplifyand increaseaccuracy of measurements formal and numericalcomplexity of thesetechniques has preventedde- in harshenvironments. Evaluations of efficiencyand accuracyrequire- tailed comparisonsof the acousticfield variableswith and without the mentsof eachof the normalincidence acoustic impedance measurement standardapproximation. Results and comparisonsfor approximateand techniquesin useat NASA LangleyResearch Center are providedto de- exact treatmentof convectionwill be presentedfrom a seriesof simple terminewhich method should be usedfor a givenproblem. The single-tone computationsmade directly from the linearized time- and space-dependent sourceimplementation of the MPM is foundto be the mostaccurate, but equationsof inviscidfluid motion.Specifically, the propagation of initially the most time-consumingtechnique currently in use. A pseudorandom planeacoustic waves in a simpleshear flow has beenaddressed to deter- noisesource implemenlation of Ihe MPM requiressignificantly less time, mine how: (i) wavefrontorientation and location,(it) acoustic-particle- with minimal lossof accuracy.The single-microphonemethod (SMM} is velocityvector direction, and (iii) acousticwave strengthcompare when shownto be accuratewith a singlediscrete frequency source, but degrades meanflow convectionis handledapproximately and exactly. [Work sup- in accuracywith a randomnoise source. potledby FordMotor Company.] 9:30 8:45 4aEA7. Time capture method for improvements in absolute 4aEA4. Acoustic radiation by a rattling plate: Experimental and calibration of accelerometersby laser interferometry. Lixue Wu theoreticalanalysis. Karen J. Leeand Karl Grosh (Dept.of Mech.Eng. (AssociatedStandards, Inst. For Natl. MeasurementStandards, Natl. Res. andAppl. Mechanics, Univ. of Michigan,Ann Arbor, Ml 48109-2125) CouncilCanada, Ottawa, ON K1A 0R6, Canada) Rattlenoise is directlytied to customers'perceptions of productqual- The measurementuncertainty in the absolutecalibration of accelerom- ity. The accurateand efficient prediction of thisnoise component remains etersusing laser interferometry was reducedby a time capturemethod. an importantand challengingarea. Sound-pressurelevels (SPLs} in the Outputsof a photodetectorand accelerometerwere digitally sampled at a acousticfield of a rattling plate were measuredexperimentally and com- rateof 256k samplesper second.Displacement amplitudes and accelerom- paredto predictionsbased on the plate'sequations of motion.The alumi- eter sensitivitieswere foundfrom the sampleddata. During data process- numplate was hingedat one and andcontacted a pointat the other.Rattle ing, a techniquewas used that decomposes a multivariable nonlinear op- wasinduced by excitingthe platesupports using a shakerwith a sinusoidal timization into a series of single-variable optimizations. This input.SPL measurements were made with a microphoneat differentpoints decompositiontechnique not only reducesthe computationalcomplexity in the acousticfield. For the initial theoreticalpredictions, the plate was but also avoidsthe convergenceto local minima.Results of calibrations modeledas a rigid body and a closed-formsolution was foundfor the showedthat the measurementuncertainty at the high-frequencyend {800 linearizedequations of motionto obtainthe contactforces. The calculated Hz) for a smallacceleration of 10 ms 2 wasless than 0.9% at 95% forcewas used to generatethe predicted plate vibration which, in turn,was confidencelevel. This time capturemethod can be appliedto any time- usedto predictthe SPL in theacoustic field surrounding the plate. Later in variant(nonsinusoidal, nonperiodic) displacement measurement. With the the study,plate flexibility was added into thecontact force model, and the abovemethod. measurement requirements such as frequencystability and effectsof addingan increasingnumber of vibrationalmodes were studied. accelerationamplitude stability, can be lessstringent. The effectsof air- The experimentaland theoreticaldata were comparedin the time and borne noise and vibration can also be reduced. frequencydomains. 9:45-10:00 Break 9:00 10:00 4aEAS.Advances in acousticpyrometry. JohnA. Kleppc (Elec.Eng. Dept.,Univ. of Nevada,Reno, NV 89557-0153) 4aEAS. A conical shock tube that simulates the heavyweightshock tests in MIL-S-901D. L. D. Luker and A. L. Van Buren (Underwater Instrumentationbased on acousticprinciples is findingwidespread use gound ReferenceDetachment. Naval UnderseaWarfare Ctr. Div. Newport, in utilityboiler applications. This paper describes how acoustic systems are P.O. Box 568337, Orlando,FL 32856-8337) currentlybeing used to measurevolumetric flow rate in largeducts and stacksfor continuousemission monitoring system (CEMS) applicationsas Sonar transducersand related componentsmounted on the hulls of well as for the measurementof high-temperatureflue gasesand boiler shipsand submarines are subjectto bothinertial shock and acoustic pres- control.Acoustic pyromerry is a usefultool for the measurementof gas sure shockwhen a weaponexplodes in the water near the vessel.Conse- temperaturesin the furnaceand superheaterregions in boilers.Results quenlly,sonar transducers are requiredto passan open-waterexplosive 2535 J. Acoust.Soc. Am., VoL 99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2535 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 shocktest using the floating shock platform (FSP) as specifiedin MIL-S- plateson the radiatingsurfaces. The acousticmeasurements were con- 901D(NAVY). These testsare expensive,infrequent, and susceptibleto ductedat both the Lake Gem Mary lake facility and the ArtecholeTest erroneousresults due to damageincurred in shipmentof the transducers Facility1 (ATFI) of theUnderwater Sound Reference Detachment in Or- betweenthe shocktest site and the acousticcalibration facility. This paper lando,FL. The presentationwill includecomparisons of free-fieldvoltage describesthe developmentof a conicalshock tube (CST) facility at sensitivities(FFVS) andtransmitting voltage response (TVR) as well as NUWC-USRD that is an inexpensive,rapid-turnaround alternative to directivitypatterns. The measurementsfrom ATFl will alsoshow the ef- open-watertesting. CST testsare performedindoors in a closed,water- fectsof hydrostaticpressure and temperatures of 4 o and22 øC. The pre- filled tubewith a 25-em-diammuzzle opening. The CST matchesthe peak sentationwill includea discussionof how specific1-3 piezocomposite pressuresobserved in theFSP test using only several grams of explosive. materialscan be tailored to meetspecific applications. [Work supported by It alsomatches the axial motionexperienced by the FSP in open-water AdvancedResearch Projects Agency and NSWC/Coastal Systems Station.] tests.Both design criteria and experimental results are presented. [Work supportedby NAVSEA.] 11:00 10:15 4aEA12. Experimentalevidence for maximum efficiencyoperation of a magnetostricfivetransducer. FrederickT. Calkins and Alison B. 4aEA9. Dynamic shear modulusmeasurement technique for very Flatau (Dept.of AerospaceEng. and Eng. Mechanics, lowa StateUniv., softmaterials. DimitriM. Donskeyand Gyoo•Cheol Bang (Davidson Ames, IA 50011) Lab., StevensInst. of Technol.,Hoboken, NJ 07030) Experimentalbroadband testing of a magnetostrictivetransducer has Existing methodsof dynamicviseoelastic properties measurements beenused to studythe trade-off between operating for maximumefficiency havesome limitation with respectto softnessof material,its spatialan- andmaximum output. Although the largestoutput, displacement or accel- isotropy,and frequency range. Specifically, there are very limited capabili- eration,is achievedat the resonantfrequency, a greateroperating effi- tiesto measuredynamic shear roedull of. very soft (real shear modulus ciencyis achievedat a frequencyabove resonance. An explanationfor this valueis below104 Pa) and anisotropic materials such as biological tissue phenomenonfor generaltransducers via the theoryof electroacousticsis and somepolymers. The proposedtechnique is intendedto fill this niche. reviewed[E V. Hunt, Electroacoustics:The Analysis of Transductionand The methodutilizes the resonanceapproach, in which the specimenwith Its Historical Background,Acoustical Society of Ameriea, Woodbury,NY certainorientation is treatedas a masslessspring attached to a massive (1982)].This frequencyof maximumefficiency is derivedfor a general rigid plate.The plateis excitedwith a one-dimensionalforced vibration in electromagnetictransducer and shown graphically on a motional- sucha way that the specimenhas only sheardeformation. The resonance impedancelocus plot. An evaluationof the efficiencyshows that the re- oscillationof the plateis analyzedwith an impedancehead and a spectral actanee,the imaginarycomponent of the electrical impedance,can be analyzer.Once the resonancefrequency and the quality factor of the reso- 'tuned'to achievemaximum efficiency. For a magnetostrictivetransducer nanceare obtained,the complexshear modulus of the specimencan be the teacrancetuning is relatedto reducingeddy losses. The effectiveper- calculated.An experimentalsetup utilizing the proposedapproach was meabilityof thematerial is shownto decreasesignificantly after resonance, built andthe complex shear meduli of softbiological tissue with respectto well below the nominalvalue at low frequency;thus operating in this different orientations of the fibers were measured. frequencyregion results in a significantdecrease in eddycurrent losses and hencea higherefficiency. Experimental results are provided to demonstrate the advantagesof operatinga transducerat the maximumefficiency fre- 10:30 quency.[Work supported by NASA GraduateStudent Research Program, 4aEAI0. Sonar dome deflection and strain measurement system. NASA Langley.] Joel F. Covey (Naval Res. Lab., Code 7135, Washington,DC 20375-5350), Diane B. Weaver,and JonathanB. Walker (SFA, Inc.) 11:15 A multiplexcdcomputer-controlled deflection and strainmeasurement 4aEAI3. Analysis of tonpiiz with flexing pistons. Alan H. Lubeli systemhas been developed for usein performingat-sea data collection on (Lubell Labs., Inc., 21 N. StanwoodRd., Columbus,OH 43209) and a Naval surfaceship sonardome rubber window.The deflectionof the RalphSimon (1777 WestwoodAve., Columbus, OH 43212) window is measuredat 128 pointson its water-filledinner surfaceby an aeonstietime-of-flight technique. At each point of interesta 2-cm-diam The acousticloading of eachof the first six modesof a doublepiston hemisphericalacoustic transducer is pulsedat 110 kHz and the signalis piezoelectricstack-driven underwater acoustic transducer is foundusing receivedby an array of four similar transducersfixed to the ship'ssonar Betman'smethod [NAA reportNA65H-1024, June 1965] revised with the array.Ten different receiver arrays are used to allow for directline-of-sight useof theHelmholtz integral formulation of Chertok[J. Acoust.Sec. Am. receptionfor eachof the pointsof interest.The 85 strainsensors were built 36, 1305-1313(1964)]. Both self and mutual impedanees are obtained and into the wire pliesof the windowby the manufacturer(B. E Goodrich). the admittanceof eachmode solved for. Finite elementanalysis is usedto The systemrecords data from all 128 transducers,all strainsensors, as well determinethe modeparameters of the first30 modesand the contribution as numerousenvironmental parameters at a rate of approximately200 to complianceloading of medes7-30. Usingsymmetry, the eight-element readingJs.The measurementsystem is nonobtrusiveto normalship sonar stackis representedby a ten-meshcircuit that includes joint compliances, operationsand performance.The data collectedis beingused in charac- end piecemasses, a distributedparameter representation of the stressbar, terizingthe behaviorof thesewindows at highspeeds and sea states and in andthe contact compliances between end pieces and pistons. lnput imped- the calibrationof numericalexperiments and window redesignefforts. anceand total radiatedpower are computedfor a wide rangeof frequen- [Worksupported by NAVSEA.] elec.For joint complianceof the orderof 0.25 E-10 M/N or less,a simpler stackmodel is foundto be adequate. 10:45 11:30 4aEAll. Measured in-water acoustic performance of 1-3 piezocompositematerials. ThomasR. Howarth (Naval Res. Lab., Code 4aEAI4. Relation between total power output and input phase of 7130, Washington,DC 20375-5350) underwater transducerarray elementsmade of piezo-rubber. Daiji Mikami,Akio Hasegawa,and Toshiald Kikuchi (Dept.of Appl. Phys., A selectionof different1-3 piezocompositematerials has been fabri- Natl.Defense Acad. of Japan,1-10-20 Hashirimizu, Yokosuka 239, Japan) catedand tested.Each of the I-3 piezocompositematerials that will be presentedwas fabricatedby the Material SystemsInc. of Littleton,MA. The mutualinteraction of underwateracoustic transducer array ele- The materialsselection includes variations in volumecontent of piezoce- mentsis oneof the mostimportant factors for its transmissionperfor- ramic,types of piezoceramic,host matrix materials of varyingcompliances mance.The poweroutput from eacharmy elementis characterizedby andair-voided microballoon content, as well as the useof typesof cover mutualradiation impedance between array elements. Recently numerical 2536 d. Acoust.Sec. Am., Vol. 99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2536 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 simulationsare often applied to solvethis kind of problem.Generally PZT Consequentlya flexible method of modelexperiment using piezo-rubber transducerarray is usedin experimentsbut mechanicalQ of PZT trans- sheettransducer array is introduced.The total poweroutput versus input duceris high and the rangeof measuringfrequency is limitedin narrow phaseof 3 x 3 piezo~rubbertransducer array provides the effectsof in- teractionbetween array elements in variousfrequencies and input ampli- hand.So manysizes of transducerarray models are required to evaluatein tudes.Also near field 3-D mappingof real power and imaginalpower differentfrequencies. Composite material piezo-rubber has unique proper- showsradiation performance of this transducerarray visually.A clear ties.Its flexibilityand broadband resonance character by low mechanicalQ power reductionwas observedin the case of a -180-deg phaseshift allow experimentsin various frequenciesutilizing one array apparatus. pattern. THURSDAY MORNING, 16 MAY 1996 HARRISON'S, 9:40 A.M. TO 1:00 RM. Session 4aED Education in Acoustics: Demonstrations in Acoustics Mardi C. Hastings,Cochair Departmentof MechanicalEngineering, The Ohio State University,Columbus, Ohio 43210-1107 JanetM. Weisenberger,Cochair Speechand Hearing Science,The Ohio State University,1070 CarmackRoad, Columbus,Ohio 43210 Chair's Introduction--9:40 Invited Paper 9:45-11:45 4aEDI. Lecture demonstrationsin acoustics. FrederickaBeiI-Berti (St. John'sUniv., Jamaica,NY 11439and HaskinsLabs., New Haven,CT 06511),E. Carr Everbach (SwarthmoreCollege, Swarthmore, PA 19081-1397),Mardi C. Hastings (OhioState Univ., Columbus,OH 43210},Patricia K. Kuhl (Univ.of Washington,Seattle, WA), andJanet M. Weisenberger(Ohio StateUniv., Columbus,OH 43210} A seriesof lecturedemonstrations in acoustics will be givento high-schoolstudents from Indianapolisarea high schools. Attendanceand participation by meetingattendees are welcome. 2537 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April 1996 131st Meeling:Acoustical Society of America 2537 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, 16 MAY 1996 CELEBRATION B, 11:00 A.M. TO 12:00 NOON Session 4aNS Noise:Progress Report and Discussionon the ContinuingActivity of ASA'sRole in Noiseand its Control Louis C. Sutherland, Chair 27803 LonghillDrive, RanchoPalos Verdes,California 90275 Invited Paper 11:00 4aNSI. Noise:Progress report and discussionon the continuingactivity of ASA'srole in noiseand i•s control. BennettM. Brooks (BrooksAcoust. Corp., Vernon, CT 06066),T. JamesDuBois (Acenteeh,Canoga Park, CA 91303),Robert M. Hoover (Hooverand Keith, Inc., Houston, TX 77082),George C. Maling (EmpireState Software, Ltd., Poughkeepsie, NY 12603),and LouisC. Sutherland(Rancho Palos Vetdes, CA 90275) A discussionmeeting sponsored byTC Noiseis beingheld to reviewprogress on activity underway or proposed. Highlighted will bea summaryof anall-day seminar on plant and product noise control, led by Dr. LucMongeau, to bepresented Friday, May 17to industrialengineers, designers and planners invited to thisoutreach effort by ASA. The report will alsoinclude an update on hearing testingactivity, presentations onnoise and acoustics to school classes by task group and other ASA members and the status of ajoint proposalby ASAand INCE submittedto theSociety of AutomotiveEngineers to adda noiseelement to theircontinuing award- winningseries of "Worldin Motion"educational packages to promotescience and mathematics literacy for grades 6-8. Thereport will alsoinclude discussion on inadequateacoustic environments in school classrooms and the resulting potential for negativeimpact on thelearning process for children. In discussionswith Stanley L. Ehrlich,president-elect of ASA and Dana S. Hougland,chair of TC ArchitecturalAcoustics, Robin M. Towneproposed this topic as worthy of ASA involvement.Thus members of TCAA andother interestedpersons are also encouraged to aUendthis session. THURSDAY MORNING, 16 MAY 1996 REGENCY A, 8:00 TO 11:00 A.M. Session 4aPA PhysicalAcoustics: Nonlinear Bart Lipkens,Chair MacrosonixCorporation, 1570 East ParhamRoad, GlenAllen, Virginia23130 ContributedPapers 8:00 8:15 4aPAI. Nonlinear surface wave propagation in crystals. M.F. 4aPA2. Secondharmonic generation in a sound beam incident on a Hamilton,Yu. A. II'inskii, andE. A. Zabolotskaya(Dept. of Mech. Eng., liquid-solid interface near the Rayleigh angle. B.J. Landsberger,M. Univ. of Texas,Austin, TX 787 i 2-1063) F. Hamilton,Yu. A. I!'inskii, and E. A. Zabolotskaya(Dept. of Mech. Eng.,Univ. of Texas,Austin, TX 78712-1063) Elasticwave propagationalong the free surfaceof a crystaldiffers from Rayleighwave propagationin an isotropicsolid. In particular,the phasespeed and depth dependence vary with the directionof propagation When a beam of soundis incident on an elastic half-spaceat the with respectto the crystallographicaxes, and the wave-vectorcomponent Rayleighangle, the rapidvariation of the phaseof the reflectioncoefficient perpendicularto the surfaceis complex.Results from a theoreticalinves- producesthe classicaleffect known as beam displacement.Considered tigationof nonlinearpropagaUon along a free surfaceof a crystalare here is the correspondingeffect on the secondharmonic component gen- presented.The analysisis basedon spectralequations that are derivedwith eratednonlinearly in the fluid. Experimentswere performedin waterwith Hamiltonianformalism. The equationswere integratednumerically to il- a 1-MHz beam radiated from a circular source of radius 1.2 cm. The beam lustratefinite-amplitude distortion of a surfacewave that is sinusoidalat was incident on an aluminumblock at several anglesnear and at the thesource. In oneexample, calculations based on publishedmaterial prop- Rayleighangle. A quasilineartheory was developed in whichthe primary ertiesare presentedfor surfacewave propagationin KCI out to distances beam is decomposedinto its angularspectrum. Analytic solutionswere beyond where shock formationoccurs. Waveform distortionassociated derivedfor secondharmonic generation by pairsof angularspectrum com- with propagationalong the [lll] axisin KCI wasfound to be similarto ponentsin the incidentand reflectedfields. The analytic solutionsare thatof Rayleighwaves in isotropicsolids. However, for propagationalong superposed,and the secondharmonic field is constructedfrom the result- the[001] axisin KCI, energytransfer from the fundamentalto thesecond ing angularspectrum. There are no restfictionson sourcegeometry or harmoniccomponent is very inefficient,and the waveformdistortion was angle of incidence.Theory is in excellent agreementwith experiment. foundto differconsiderably from that of Rayleighwaves. [Work supported Calculationsreveal that in the reflectedfield, secondharmonic components by NSF,ONR, andthe SchlmnbergerFoundation.] generatedseparately in the incidentand reflected beams combine construe- 2538 J. Acoust. Soc. Am., Vol. 99, No. 4, Pt. 2, April 1996 131st Meeting: Acoustical Society of America 2538 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 tively in regionsassociated with specularreflection, and destructivelyin the high-frequencytail of fully developedshockless noise is observedto be regionsassociated with radiationby the Rayleighwave. [Work supported anf-a powerlaw in thefrequency f, in accordwith theory. This power by ONR andthe SchlumbergerFoundation.] law is a consequenceof the far off equilibriumnature of thesystem. [Work supportedby ONR.] 8:30 9:15 4aPA3. Nonlinear acoustic nondestructive testing of cracks. 4aPA6. Nonlinearity versus diffraction within a focusing weak AlexanderM. Sutin (Inst.of Appl.Phys., Russian Acad. Sci., 46 Ulyanov shock. AndrewA. Piacsek (LawrenceLivermore Natl. Lab., Univ. of str.,Nizhny Novgorod 603600, Russia) California, P.O. Box 808, Livermore. CA 94551) This paperis a review of new nonlinearacoustic methods. Acoustic In a classicpaper treating the propagationof weak shocks,Whitham imagingand NDT methodsare widely used in variousteenteal fields. elucidatedthe processby which nonlineareffects would prevent rays Conventionalmethods are based on theprinciples of linearacoustics: Non- within a concaveportion of a shockfront from intersecting,thereby avoid- lineardistortions are ignored.The strengthof the distortioncan highly ing a foldedwavefront and associated caustics [G. B. Whitham,J. Fluid increasedue to thecompliant features of thecracks. Such distortion can be Mech. 1, 290-318 (1956)]. Whitham'sanalysis neglected the effectsof observedby usingdifferent nonlinear effects such as high-harmonicgen- diffractionarising from a finite shockthickness. When this lengthscale is eration,modulation of soundby vibrations,and subharmonicgeneration. small comparedto that of the wavefront'scurvature, Whitham's nonlinear Nonlinearacoustic methods are basedon theseeffects and examples of its correctionto geometricalacoustics is a goodmodel for thedevelopment of usageare varied.First. a similarmethod was developedwhich testedthe the shockfront. When the lengthscales are comparable,as they are near gluequality of thermoprotectivecovers of the RussianBuran space shuttle. the focalpoint, diffraction becomes important and actsboth in conjunction Using a nonlineareffect of high-frequencysound modulation by vibra- with nonlinearity(to limit the shockamplitude) as well as againstit (in- tions,an enormousincrease of the acousticnonlinear parameter in steel hibiting the refractionof rays). Recentnumerical studies [A. Piacsek, that has beenfatigued has been experimentally demonstrated. The single Ph.D. thesis,The PennsylvaniaState University (1995)] indicatethat the microcracks in metal ½onslruction were detected as well. The method latter effect can lead to the formationof a foldedwavefront, bounded by basedon second-harmonicgeneration due to crackswas testedin firm caustics,just as linear geometrictheory predicts.The presentpaper ad- "PECITINEY" in France.The sensitivityof nonlinearnew methodsto the dressesquantitatively how the relativeimportance of nonlinearityand dif- appearanceof fatiguedamage to the materialis muchlarger than that of fraction(as represented by theshock amplitude, thickness, and wavefront conventionalmethods of NDT.[Work was supported by RussianFounda- curvature)determines the behaviorof a focusingweak shock. [Work per- tionof FundamentalResearch Grant N0-93-05-8074.] formedby the LawrenceLivermore National Laboratory under U.S. De- partmentof EnergyContract No. W-7405-ENG-48.] 9:30-9:45 Break 8:45 4aPA4. Propagationof finite-amplitudebroadband noise. Penelope 9:45 Menounouand David T. Blackstock (Appl. Res. Labs.,Univ. of Texas, Austin,TX 787i 3-8029 and Mech. Eng. Dept., Univ. of Texas,Austin, TX 4aPA7. Generation of localized low-frequency vibrations by remote 78712-1063) ultrasound sources. Mosturn Fatemi and James F. Greenleaf (BiodynamicsRes. Unit, Dept. of Physiol.and Biophys.,Mayo Clinic/ Burgers'equation is usedto predictthe effect of nonlinearityon the Foundation, Rochester,MN 55905) powerspectral density of planebroadband noise traveling in a nondisper- sive thermoviscousfluid. The sourcesignal is assumedto be stationary This paperpresents a new methodof inducinglocalized low-frequency Gaussiannoise, which, because of nonlinearpropagation distortion, be- acousticenergy in an objectby remotesources. In this methodtwo inter- comesnon-Gaussian as it travels.As opposedto time-domainmethods, the actinghigh-power, high-frequency. ultrasound beams at two differentfre- methodpresented here is baseddirectly on the powerspectral density of quenciesare used.These beams are posilionedto interactat the object's the signal,not the signalitself. The Burgersequation is transformedinto an surface(or any other impedance discontinuity inside the object}. The result unclosedset of linear equationsthat describethe evolutionof the joint is a radiationforce at the differencefrequency, df, exertedin a smallarea momentsof the signal.A methodfor solvingthe systemof equationsis definedby the beamwidths.Experiments are performedon a small steel presented.Only the evolutionof appropriatelyselected joint moments needleand blocks of gelatin. To monitor the vibration, a high-frequency needsto be calculatedin order to predict the evolutionof the power probingtransducer is usedin pulseecho mode with the beamaimed at the spectraldensity of the signal.The resultsare in goodagreement with a vibratingpart of the object.This transducershoots tone bursts at a rate time-domaincode [Clevelandeta!., J. Acoust.Soc. Am. 98, 2865(A) muchhigher than dL Echoesare quadraturedetected and the resulting (1995)].The methodcan be alsoapplied when the sourcecondition is a in-phaseand quadrature signals are recorded.These signals are usedto stationary,ergodic, and Gaussian stochastic process. [Work supported by calculatethe phase of thereturned echo which is shownto be proportional NASA.] to the targetdisplacement. In the experiments,the powerbeams were drivenat 20 W eachand df = 10 Hz. Amplitudeof the resultingvibrations were 5/•m for the gelatinblock and 1.2 pm for the needle. 10:00 4aPA5. Absorptionof sound by noise in one dimension. Andr•s Larraza (Dept. of Phys.--Code PH/La. Naval Postgrad.School. 4aPA8. Nonlinear effects on acoustic field measurement in Monterey,CA 93943) and Brace Denardo (Univ. of Mississippi, biomedicalfrequency range. S.G. Ye, X. F. Gong,and X. Z. Liu (Inst. University,MS :38677) of Acoust.and Lab. of Modem Acoust.,Nanjing Univ., Nanjing 210093, People'sRepublic of China) Experimentalresults are presentedfor theexcess attenuation of toorio- frequencywaveg in the pregeneeof high-intensitynoise in one dimension. It was shownthat ultrasoundpropagation in mediais accompanied The theoryby Rudenkoand Chirkin predicts a Gaussianattenuation of a with nonlinearphenomena and the nonlinear effects on themeasurement of weaksignal in thepresence of shocklessnoise, thus showing that in one acousticfield cannotbe neglected.A needlehydrophone was used to re- dimensiontranslational invarianee has been broken. The theoryis modified ceivethe signalin the acousticfield for furtheranalysis and the radiation to incorporatewall lossesproviding, only then,excellent agreement with forcemethod was used to measurethe total output power of thetransmitter. experiment.The agreementis shownas the frequency,noise level. and The caseof emittingpower was constant,the nonlinearphenomena were distancefrom the sourceare varied.In addition,the spectralintensity of accumulateddue to the distancebetween the transmitter,and the hydro- 2539 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society of America 2539 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 phoneincreased from a few centimeterto lessthan 20 cm.With increasing field in the channelare developedin a generalizeddimensionless form distancebetween the transmitterand the hydrophone,the ultrasounden- whichallows for compressibilityeffects in the fluid, and alsofor thermal ergy was graduallytransferred from fundamentalfrequency f0 to high effectsdue to wall-fluid couplingto be treated.It is verifiedthat for gaps harmonics.Using the spectrumanalyzer, the dependenceof f0 and nfo wide with respectto the thermalpenetration depth (Y013,,>> 1, Y0: channel (n = 2,3.... ) on the distanceincreased was measured.When the distance gaphalf-width, •5,,: thermal penetration depth), the classic results of Ray- betweenthe transmitterand the hydrophonewas fixed, the nonlinearphe- leigh,including the recent modifications to it [Q. Qi, I. Acoust.Soc. Am. nomenabecame stronger as the emittingpower increased. The acoustic 94, 1090-1098 (1993)], are recovered.However for caseswhere Yo and intensityoff0 wasno longerlinearly increased with theincreased emitting 8• arecomparable, as in the stackofa tbermoacousticengine, the situation poweracoustic intensity, and the acousticintensity of f0 wouldtend to- is considerablydifferent and indicatesthe presenceof strong steady warda saturationvalue. [Work supported by NSFC.] streamingflows in the channelwhich could provide an explanationfor the jets experimentallyobserved at theends of sucha channelas reported at an 10:15 earliermeeting [Gaitan et el., J. Aeoust.Soc. Am. 96, 3220(A) (1994)]. 4aPA9. Active acousticstabilization of capillary bridgessignificanfiy Steadyflows of this typehave an importantbearing on the designof heat beyond the Rayleigh limit: Experimental confirmation. Mark J. exchangerslocated at the endsof the stackin a thermoacousticengine. Mart-Lyon,David B. Thiessen,and Philip L. Marston (Dept.of Phys., WashingtonState Univ., Pullman, WA 99164-2814) Liquidbridges between two solidsurfaces have applications in low gravitysuch as the solidificationof floatingzones. Long bridgesnaturally 10:45 becomeunstable to a symmetricmode by bulgingnear one end while the oppositeend thins. For a cylindricalbridge in low gravityof radiusR and 4aPAII. Acoustic sensing of the nonlinear dynamics of density lengthL, the slendernessS= L/2R hasa natural(Rayleigh) limit of •' stratified vortices. Alexander B. Ezersky, Poul L. Soustoy, and beyondwhich the bridgebreaks. It has beendemonstrated that acoustic AlexanderB. Zobnin (Inst. of AppL Phys.,Russian Acad. Sci., 46 radiationpressure may be usedin simulatedlow gravityto producestable Ulyanovstr., Nizhny Novgorod 603600, Russia) bridgessignificantly beyond the Rayleighlimit with S as largeas 3.6. The bridge(PDMS mixedwith a denseliquid) has the samedensity as the Dataon thenonlinear processes in an atmosphereand in theocean may surroundingwater bath containing an ultrasonicstanding wave. Modula- be obtainedby meansof remoteacoustic sensing. The principaltask is to tioncan be used to excitespecific bridge modes [Morse et el., Phys.Fluids 8, 3-5 (1996)].The shapeof ourbridge is opticallysensed and the ultra- use the data obtainedin experimentsfor reconstructionof temperature, sonicdrive is electronicallyadjusted such that the radiationstress distri- pressure,and velocity fields, and thus reconstructthe flow. Resultsof butiondynamically quenches the mostunstable mode. This activecontrol laboratoryinvestigations of the potentialitiesof remoteacoustic sensing of simulatespassive stabilization suggested for low gravity[J. Acoust.Soc. flows are presented.The scatteringof soundat vorticesbehind a cylinder Am. 97, 3377(A) (1995)].Feedback increases the modefrequency in the was explored.The temperatureof the coresof the vorticesformed as a naturallystable region. [Work supported by NASA.] boundarylayer wasdetached from the heatedcylinder was higher than that of the incidentflow. The experimentwas performedin a low-turbulence 10:30 wind tunnel at flow velocitiesmuch lower than the soundvelocity. It is shownthat the characteristicsof the scatteredsignal (indications of scat- 4aPA10. Acoustic streaming in a resonant channel. Ashok Gopinath teringand time spectra) may be usedto determinevortex parameters such (Dept. of Mech. Eng., Naval Postgrad.School, Code ME/Gk, Monterey, as vorticity,repetition rate, and spatialperiod, to estimatethe temperature CA 93943) of vortexcores and the amountof the heattransferred, as well asto identify The problemof acousticstreaming in a planeparallel channel support- the processesof vortex mergingand vortex core oscillations.Results of ing a resonantstanding acoustic wave is considered.The channelis rep- acousticsensing are in a good agreementwith theoreticalestimates, direct resentativeof one of the multitudeof channelstypically present in the measurementsby a bot-wire anemometer,and data of experimentson stackof a thermoacousticengine. The governingequations for the flow vortex visualization. THURSDAY MORNING, 16 MAY 1996 REGENCY C, 8:00 A.M. TO 12:00 NOON Session 4aPP Psychologicaland PhysiologicalAcoustics: Detection, Discrimination and Masking Virginia M. Richards,Chair Departmentof Psychology,University of Pennsylvania,3815 WalnutStreet. Philadelphia, Pennsylvania 19104 ContributedPapers 8:00 with 2-kHz AM. A linearregression of logd' on 20 log m showedthe slopeof thefunctions ranging from 0.83 to 1.59in thegered conditions and 4aPPI. AM detection with one- and two-tone modulators. Stanley from i.34 to 1.79 in the continuous conditions. The increase in function Sbeftand William A. Yost (ParmlyHearing Inst., Loyola Univ., 6525 N. slope betweenthe gated- and the continuous-carrierconditions was less SheridanRd., Chicago,IL 60626) than predictedby Laming'smodel of sensoryprocessing [D. Laming, Psychometricfunctions were measuredfor detectingamplitude modu- SensoryAnalysis (Academic, New York, 1986)].AM detectionability was lation (AM) of a widebandnoise carrier that was either gatedwith the also measured with two-tone modulators centered at either 2 or 6.5 kHz. 400-ms modulatoror was on continuously.AM rateswere 5, 20, 80, and Modulatortones were separatedby 5, 20, or 80 Hz. Performancewith the 2000 Hz. The functionswere steepest at the 80-Hz AM rateand shallowest two-tonemodulators was often better than predicted by eitherthe envelope 2540 J. Acoust.Soc. Am., Vol.99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2540 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 rms or max/min value,especially with the tonescentered at 6.5 kltz. This variancesof the classicalenergy fluctuation and of a waveformfluctuation resultis consistentwith incorporationof a secondnonlineartry into a model due to random phases.For TW<20 the energy fluctuationdominates, of auditoryenvelope detection, introducing intermodulation at the low- while the waveformfluctuation dominates for largerTW. Predictionsof modulatorbeat rates. [Work supported by NIH.] the classicalenergy detection model with an internalnoise of I dB are essentiallyindistinguishable from the peak detectormodel for intensity discriminationthresholds of narrow-bandGaussian noise; however, peak 8:15 detectionexplains a wider range of experiments[Goldstein, J.Acoust. Soc. 4aPP2. Effects of frequency,increment and decrementduration, and Am. 98, 2907(A) (1995)]. pedestalduration on the detectionof incrementsand decrementsin sinusolds. RobertW. Peters (Div. of Speechand Hear.Sci. and Dept. of 9:00 Psych.,CB# 7190. Univ. of North Carolina,Chapel Hill. NC 27599-7190) and Brian C. I. Moore (Univ. of Cambridge,Cambridge CB2 3EB, 4aPPS. Mechanisms of FM detection. Brian C. J. Moore and England) AleksanderSek (Dept. of ExperimentalPsych., Univ. of Cambridge, DowningSt., CambridgeCB2 3EB, England) Thresholds for detection of increments and decrements in level of sinusoidalsignals were measuredas a functionof signalduration (10, 20, In experiment!, thresholdsfor detectingFM weremeasured for carrier or 200 ms),pedestal duration belbre the signal( 10, 200 ms,or pedestalon frequenciesf, from 0.25 to 6 kHz and for modulationrates f,, from 2 to continuously)and frequency(250, !000, and 4000 Hz). Pedestalduration 20 Hz, usinga 2AFC task.To disruptcues based on changesin the exci- was variedto studyadaptation effects and signalduration was variedto tationpattern, thresholds were also measuredwhen the cardersin both studytemporal integration. The sinusoldswere presented in a background intervalsof a trial were amplitudemodulated at the samerate as the FM noiseintended to maskspectral splatter. Seven normal-hearing subjects with a modulationindex of 0.333. The phaseof the AM relativeto the FM were used.Thresholds improved with increasingfrequency and with in- wasrandomized. Forf½< 4 kHz, the deleteriouseffect of theAM increased creasedduration for bothincrements and decrements. Increasing the ped- with increasingf,,. For ft. = 6 kHz, the effect was independentoff,. [n estalduration before the incrementfrom 10 to 200 msgenerally improved experiment2, psychometricfunctions were measuredfor detectingcom- the threshold for increment durations of 10 and 20 ms but not for an binedFM andAM, withf,, = 2 Hz, as a functionof the relativephase of incrementduration of 200 ms. When the pedestalwas on continuously, the modulators,using modulation depths for AM and FM that would be distinctadaptation occurred at 4000 Hz; the pedestalappeared to fade equallydetectable if eachwere presented alone. Relative modulator phase away.However, this did not greatlyaffect increment thresholds, except for had no effect for f½= 0.25 kHz, smalleffects for fc = 1 kHz, and large a slight improvementfor the incrementduration of 200 ms. Decrement effects for fe = 6 kHz. The resultssuggest that a temporalmechanism thresholdsgenerally became worse when the pedestal was on continuously. dominatesFM detectionfor f•<4 kHz, andfor f,•= 2 Hz. A placemecha- The resultsare discussed in termsof the effectsof adaptationand temporal nismdominates for highcarrier frequencies, and for lowercarrier frequen- imegration. cies wbenf,,• TM10 Hz. 8:30 9:15 4aPP3. Detectionof change without regard to its valence. Ervin R. 4aPP6. Masking additivity in an excitation-pattern model. B. Halter, Anne-MarieBonnel, and Erick J. Gallun (Dept. of Psych..Univ. Espinoza-Varas (CommunicationSciences & Disorders, Univ. of of California, Berkeley,CA 94720) OklahomaHealth SciencesCtr., OklahomaCity, OK 73190) Whenan increment(S + ) or a decrement(S- • is addedto an ongoing An excitation-patternmodel [Moore and Ginsberg, Hear. Res. 28, 209- pedestalin a detectiontask, performance is far betterthan when all trials 225 (1987)]was used to predictthe maskingadditivity of two simulta- havea signaland the taskis to ident•' its valence.This is the oppositeof neous sinusoidalmaskers. The predictionrelies on the assumptionthat predictionsfrom a standarddetection theoretical analysis. It hasbeen sug- maskedthreshold is reachedwhen the additionof the signalto the musket gestedthat the detectiontask reflectssensitivity to transientsassociated producesa critical difference in themusket excitation pattern (EP) at any with stimuluschange while identificationtask reflects analysis of the sus- centerfrequency (the critical EP differenceis termedcriterion EPD). For tainedlevel, i.e., theenergy. To becomplete, this must argue that detection equallyeffective muskets, masking additivity was assumed be equalto the is of absolutechange, regardless of its sign.To testthis, detectabilitywas differencebetween two signallevels: The level thatproduces the criterion measuredwith bidirectionalsignals (S+) and (S-) was comparedthat EPD with the combinationof maskersminus the level that producesthe with only a singlesignal type, either (S+) or (S-). This was done in criterionEPD with the individual maskers.Excitation-pattern predictions paradigms:(1) with thepedestal constant and (2) with gapsin thepedestal of maskingadditivity were obtainedfor signalfrequencies of 500. 1000, on eitherside of the signalthat preventedthe usechange per se. Results and 5000 Hz. each masked by two sinusoidalmuskets symmetrically show the hypothesis,showing that monodirectionalsignals were equally placedabout Ibe signalfrequencies; muskets frequencies within and out- detectableas bidirectionalsignals when there were no gapsbut with gaps, sidethe signalERB were considered.The maskingadditivity predicted by they were better. the EP model is comparedto that predictedby the modified power law 1' model[Humes et al., .l. Acoust.Soc. Am. 83, 188-202 (1988)].and to masking-additivitydata [Lutfi, I. Acoust.Soc. Am. 73, 262-267 (1983)]. 8:45 4aPP4. Stimulus fluctuations in auditory intensity discrimination. 9:30 lulius L. Goldstein (Central Inst. for the Deaf, 818 S. Euclid Ave., St. Louis, MO 63110} 4aPP7. Processing transitions in a band-widening experiment. Bruce G. Berg, Curt Southworth.and Brian K. Branstetter (Dept. of A basic predictionof Green's[J. Acouat.Soc. Am. 32, 121-131 Cognit.Sciences, Univ. of California.Irvine, CA 92717) ( 1960)]classical energy-detection theory for Gaussiansignals is a variance measureof stimulusfluctuation that decreasesmonotonically with the sig- Literaturesuggests that in the absenceof single-channellevel informa- hal's duration-bandwidthproduct (TW). Experimentson intensitydis- tion,discriminations of narrow-bandsounds are temporallybased, whereas criminationof narrow-bandGaussian noise provide the mostdirect support discriminationsof widebandsounds rely on across-channellevel compari- of thisprediction for TW< -- 16, but indicatea needfor anothersource of sons. The transitionbetween processes is investigatedusing a band- fluctuationfor largerTW whichcould reflect internal noise [deBoer, I. wideningparadigm. Thresholds are estimatedfor incrementsin the inten- Acoust.Soc. Am. 40, 552-560 (1966)].An alternativesolution is proposed sity of the centraltone of a bandof equalintensity, random phase tones basedon detectionof the largestwaveform peak within the analysiswin- evenlyseparated in frequency(parametrically varied between 10 and 160 dow { >• T). Investigationof this detectorfor narrow-bandGaussian noise Hz). A 20-dB roving-levelprocedure degrades overall-level information. showsthat the variance(in dB) of the peak fluctuationsis the sumof the Uniformlydistributed frequency shifts of thecomplex over a 100-Hzrange 2541 J. Acoust. Soc. Am., Vol. 99, No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society of America 2541 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 degradepitch cues.As the numberof tonesis increased,thresholds in- 10:30 creaseup to a certainbandwidth, after which thresboids decrease or remain 4aPP10, Toward a simple resolution of the temporal constant.It is proposedthat thesebreakpoints in thresholdfunctions rep- resolution/integrationparadox. C. Formby (Div. of Otolaryngol.-Head resenta transitionfrom temporalto spectraldiscrimination processes. The & Neck Surgery,Univ. of MarylandSchool of Medicine,16 S. Eutaw,Ste. meanratio of breakpointsto centerfrequencies of 500, 1000, 2000, and 500, Baltimore,MD 21201), T. G. Forrest (Cornell Univ., Ithaca, N¾), 4000 Hz is approximately0.4. Regardingindividual differences, a signifi- M. G. Heinz (Harvard-MIT, Cambridge,MA 02139), S. E. Hargus, cant positivecorrelation exists between breakpoints and thresholdsin a andJ. W. Zeiders (Univ. of MarylandSchool of Medicine,Baltimore, MD widebandprofile analysis task. [Work supported by ONR.] 21201) Green[Time Resolution in Auditor),Systems, 1985] distinguishedbe- tweentwo broadclasses of paradigmsthai presumablyrepresent the two endsof the auditorytemporal processing continuum. At one extremeare 9:45 measuresof temporalintegration (TI) that estimatethe maximumtime over which acoustic information can be stored. At the other extreme are 4aPPS. The effects of center frequency and bandwidth on the measuresof temporalacuity/resnlution (TA) thatestimate the briefestde- discriminabilityof noise. Martin E. Rickerrand Donald E. Robinson tectablechange in acousticinformation. The goal of bothparadigms is to (Dept.of Psych.,Indiana Univ., Bloomington,IN 47405) estimatea time constant(•') for the auditory system.Traditionally, ri reportedfor TI is more than an orderof magnitudelonger than •'n esti- When listeners are asked to discriminate between trials on which a matedfor TA. The aim of this studywas to resolvethis apparentparadox. sampleof noiseis presentedtwice and trials on which two nonidentical Detection thresholdswere obtained for a range of brief bandlimited samplesare presented, discriminations are easier if samplesdiffer nearthe (Wu=62-6000 Hz) incrementswithin a broadbandnoise to estimater in endrather than near the beginning.The effectof temporalposition IS. F. TI andTA tasksfrom the samelisteners. For eachWt• condition,detection Cobleand D. E. Robinson,J. Acoust.Soc. Am. 92, 2630-2635(1992)] is thresholdswere measuredas a functionof (1) incrementduration robustover a wide rangeof stimulusparameters including duration, level, (Pt•= 10-480 ms)by trackingincrement level adaptively to estimate?l and correlation.In previouslyreported work [M. E. Rickerrand D. E. and(2) incrementlevel by trackingincrement duration adaptively to esti- Robinson,J. Acoust.Soc. Am. 98, 2906(A) (1995)],discriminability was mate r^. The resultingr l and r^ estimatesare comparableand vary in- measuredwith wideband(100-3000 Hz) and narrow-band(455-655 Hz) verselywith Wt• fromabout 70 to 7 ms.[Research supported by NIH.] noise. The size of the effect of temporalposition is smaller with the narrow-bandnoise. However, one could argue that theseeffects are re- 10:45 strictedto the lower region of the frequencyspectrum because center frequencywas held constant (• 545 Hz). In theexperiment reported here, 4aPPll. Fast-acting compression in human hearing. Robert P. both centerfrequency (545 and 2000 Hz) and bandwidth(200 and 1000 Carlyonand A. JaysuryaDatta (MRC Appl.Psyeh. Unit, 15 ChaucerRd., Hz) wereinvestigated. Data were also obtained with wideband(100-3000 CambridgeCB2 2EF, England) Hz) noise.Although the effectof temporalposition is consistentacross stimulus conditions, the size of the effect is reduced for narrower band- Physiologicallymotivated auditory models calculate excitation from a widths.There is no evidenceof an effectof centerfrequency. Results are compressedand rectifiedversion of auditoryfilter responses.Unlike the discussedin terms of a leakyintegrator model [D. E. Robinsonand M. E. "powerspectrum" model, they predict that, when the responsesof a filter Rickeft,J. Acoust. Soc. Am. 98, 2906(A)(1995)]. [Work supported by NIH to two soundshave equal power but differentpeak factors,the sound andAFOSR.] producingthe lesspeaked response will producemore excitation. This was confirmedby experimentsusing two sounds,each consisting of harmonics 2-20 of a 100-Hz fundamental,presented at 68 dB SPldharmonic,and 10:00-10:15 Break with theharmonics summed in eitherpositive or negativeSchroeder phase. Kohlrauschand Sander [J. Acoust.$oc. Am. 97, 1817-1829(1995)] have shownthat the responseof an auditoryfilter centeredon 1100 Hz to the positivephase complex is highly modulated,whereas that to the negative phasecomplex is not. It is reportedthat the thresholdfor a 10-ms 1100-Hz 10:15 signalpresented 5 ms afterthe positive phase stimulus is approximately10 4aPP9. Simulationsof temporal resolutionand integration data with dB lessthan after the negativephase stimulus. Also, listenersjudged har- a computer model using a modulation filter bank. Stefan M/inkner monics9-13 of thepositive phase sound to be quieterthan the correspond- (lII. Phys.Inst., G/•ttingen, Germany) and Attain Kohlrausch(Inst. Pere. ing harmonicsof the negativephase sound. It is concludedthat the results Res. (IPO), Eindhoven,The Netherlands) reflectfast-acting compression in the humanauditory system. Temporalresolution and temporal integration in theauditory system, 11:00 with their conflictingtime constants,are often regardedas paradoxphe• 4aPP12. Peripheral origins of the upward spread of masking. nomena.In this studya modelis presentedfor the simulationof a number AndrewJ. Oxenham (Inst.for Percept.Res. (1PO), P.O. Box 513, 5600 of temporalresolution experiments (e.g., gap detection, forward masking) MB Eindhoven,The Netherlands)and ChristopherJ. P!ack (Lab. of and classicaltest tone integrationdata (cf. contributionsby Dan et al.). ExperimentalPsych., Univ. of Sussex,Brighton BNI 9QG, England) The modelconsists of two major parts.A preprocessingstage that trans- formsthe acousticstimulus into an internalrepresentation, simulating the Recent physiologicalstudies have shown that the basilar membrane peripheralprocessing in the auditorysystem. Processing errors are ac- (BM) responseto tonesat characteristic frequency (CF) is highly compres- countedfor by addinginternal noise which introducesdetection limits. The sire at mediumlevels, with a ratioof about5:1, whilethe response to tones secondstage is an optimumdetector to simulatea 'central'decision device. well belowCF is linear.A psychophysicalmeasurement of thesecharac- The preprocessingstage consists mainly of threesubunits: a Gammatone teristicswas attempted using forward masking, to avoidperipheral inter- filterbankto simulateperipheral filtering; a setof adaptivefeedback loops actionof stimuli,with a 4-ms,6-kHz signalpresented 2 ms after the o•fset thatderives an adaptedenvelope of everyperipheral filter output; a modu- of a 100-ms,3-kHz masker,in orderto measurethresholds at high signal lationfilterbank (per peripheral channel) that analyzes stimulus periodici- levels.The growthof maskingwas very compressireat mediumsignal ties in theseadapted representations. The model is able to simulategap levels;increasing the signallevel f•om 50 to 70 dB $PL resultedin a mean detectionand test tone integrationexperiments quantitatively without increasein maskerlevel of only3.6 dB. Growthat lowerand higher signal changingits parameters.It can be shownthat within this modelthe modu- levels was more linear. Thresholds were also measured for a number of lation filterbankis vital to achievethis performance.[Supported by the othermasker frequencies. As expected,the differencebetween masker and DFG (Az. Mu/1201).] signalgrowth rate decreased as the masker•equency approached signal 2542 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2542 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 frequency.The resultsare quantitatively consistent with the hypothesis that difficultyof separatingthe influenceof excitationand inhibition in simul- BM nonlinearitygoverns the upwardspread of masking.Furthermore, the taneousmasking. Here, the forward-masked threshold of a 20-ms,1000-Hz techniquemay providea simple way of estimatingBM nonlineartryin tonewas determined in thepresence of oneor two maskingtones [MI humans.[Supported by theWellcome Trust and the Royal Society.] (1000Hz, 50 dB) andM2 (variablefrom 500 to 3000Hz, 70 dB)].When the maskerduration was 500 ms,adding M2 to M 1 reducedsignal thresh- 11:15 old whenM2 waspresented at 1150Hz (suppression),but had no influence onperformance when M2 wasabove about 1300 Hz. In contrast,when the 4aPPl3. Basilar membranenonlineartry and the growth of forward maskerduration was 40 ms, addingM2 to M I did not lowerthreshold at masking. ChristopherJ. Pluck (Lab.of ExperimentalPsych., Univ. of 1150Hz, and alwaysincreased threshold when M2 was presentedabove Sus•x, BrightonBNI 9QG, England)and Andrew 1. Oxenham (Inst.for 1300 Hz. This latterthreshold increase was reduced when a third masking Percept.Res. (IPO). P.O.Box 513, 5600 MB Eindhoven,The Netherlands) tonepresented at 1150Hz wasadded to Ml andM2. Theseresults suggest that the across-channelprocess involved in the enhancementeffect is ex- Psychephysicalforward masking generally grows nonlinearly, with a citatory,adapts, and is moderatedby suppression.[Work supportedby given increasein signallevel requiringa largerincrease in maskerlevel for NIDCD.] the signal to remain at threshold.In the presentexperiments, a 10-ms sinusoidalsignal was presented 2 msafter a 20-mssinusoidal masker at the 11:45 samefrequency. Frequencies of 2 and 6 Idtz were tested.It was shown thai,while the masker level needed grew faster than the signal level at low 4aPPI5. New masking experiments using low-noise noise muskets. signal levels, at medium signal levels the reversewas the case.These ArminKohlrausch (Inst. Percept. Res. (IPO), P.O.Box 513, NL-5600 MB resultscan be understoodin termsof a basilarmembrane response that is Eindhoven,The Nethernods) compressireat mediumlevels and more linear at low and high levels. Low-noisenoise generally refers to narrow-bandnoise with a flat tem- When the maskeris in the compressireregion and the signalis in the poralenvelope. Hartmann and Pumplin [J. Acoust.Soc. Am. 83, 2277- lower,more linear. region, then large increases in maskerlevel are needed for a small increasein signallevel. When the signalis in the compresslye 2289 0988)] usedone 100-Hz-widelow-noise noise sample to maska sinusoidalsignal, and found that thresholdswere 5 dB lower than for a region and the maskeris in the higher, more linear, region, then large increasesin signal level are neededfor a small increasein maskerlevel. comparableGaussian noise. These experiments were performedas frozen- [Work supportedby the Royal Societyand the WellcomeTrust.] noise measurementsand the thresholdvalues were the averagesof the resultsfor six differentsignal starting phases. The thresholdsfor the signal in Gaussiannoise (about - ] I-dB signal-to-overall-noiseratio) werecon- 11:30 siderablylower thanthresholds typically found in a random-noisepresen- tation (-3 dB). The experimentsreported here were initiatedto test 4aPPI4. Psychephysicalevidence of excitatory connectionsacross whetherthe differencein maskingbehavior between low-noise noise and auditoryfrequency channels. BeverlyA. Wright (KeckCtr., P.O.Box 0732, Univ. of California,San Francisco,CA 94143-0732) Gaussiannoise is alsoobserved in a random-noiseexperiment and how it dependson maskerbandwidth and signal duration.In a 100-Hz-wide A simultaneouslymasked auditory signal becomes easier to detectas masker centered at 1000 Hz, the same difference of about 5 dB was found. its onsetis delayedfrom maskeronset. This "enhancementeffect" de- This differenceincreases with decreasingmasker bandwidth, reaching a pendsupon maskingcomponents presented outside of the signal'sfre- maximum of 9.5 dB for a 10-Hz-wide musket. The difference also in- quencychannel, indicating the participationof an across-channelprocess. creasessomewhat with decreasingsignal duration, from 5 dB for a 500-ms The natureof this processhas not been clearly establisheddue to the signalto 7.6 dB for a 20-mssignal. THURSDAY MORNING, 16 MAY 1996 CELEBRATION A, 8:15 TO 11:45 A.M. Session 4aSA Structural Acousticsand Vibration: Scattering Guillermo C. Gaunaurd, Chair CardcrockDivision, Naval SurfaceWarfare Center, White Oak, Code684, Silver Spring,Maryland 20903-5640 ContributedPapers 8:15 of thesewavepackets are shownto vary with targetaspect angle. This angulardependence isshown to be related to physical mechanisms. [Work 4aSA1. Angular dependence of Bloch wavepackets. Charles E supportedby NRL 6.2 funds.] Ganmend and David Drumheller (Naval Res. Lab., Code 7140, Washington.DC 20375-5350) 8:30 The contributionto an echo by a particularscattering mechanism, 4aSA2. (Bragg mode)-(leakymode) couplingdue to a finite periodic whichoccupies a specificregion in the time-frequencyor time-scaledo- array of scattererson a submergedelastic layer. RaymondJ. mains,is definedas a wavepacketIN. Yen,J. Acoust.Sec. Am. 81, 1841- Nagem,Leopold B. Felsen,and Brian J. Collins (Dept.of Aerospaceand 1850 {1987}].Previous studies have isolated wavepackets generated by Mech.Eng., Robton Univ.. 110Cummington St_. Boston. MA 02215) specularreflection, Bragg reflection and Blochwaves in backscattered echoesfrom a ribbed,finite cylinder at a few discretetarget aspect angles. Couplingof energyinto andout of submergedlayered elastic topog- For thistarget, the echoes mainly contain components from specular re- raphiesvia scatteringcenters on the top surfaceis of interestfor a variety flectionand Bloch wavesin the frequencyregion near kay5. Thesetwo of applicationsin bottom-interactingacoustics. To understandand param- kindsof wavepacketsare experimentallyextracted in the time-scaledo- etrizethe basic wave phenomena which are operativehere, this study was mainover the angular range from 10ø to 70ø. The timeextents and spectra begunwith a simplemodel whereina finite periodicarray of scatterers 2543 d. Acoust.Sec. Am., Vol. 99, No. 4, Pt. 2, April1996 131st Meeting:Acoustical Society' of Amedca 2543 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 situatedon a singleelastic layer is insonifiedby an incidentplane wave. 9:15 The problemis analyzedrigorously by spectralwave-number decomposi- 4aSA5. Backscattering due to ray reverberations between tion, and the scatteredfields are obtainedby asymptoticevaluation of the nonconcentric surfaces of a thick shell: Ray stability, transitions in spectralintergrals. The results can be interpretedin terms of army- wavefront shapes, and observed scattering enhancements due to modifiedleaky wavesand slab-modifiedBragg modes.with Bragg-leaky focusing. ScotF. Morseand Philip L. Marston (Phys.Dept., Washington modecoupling occurring due to end effectsas well as bulk effectsof the State Univ., Pullman,WA 99164-2814) array.The couplingeffects are optimizedwhen one of the slab-modified modesis phasedmatched to one of the Bragg modes.The asymptotic The paraxialray stabilityanalysis previously developed for laserreso- algorithmsare calibratedagainst numerically evaluated spectral integral natorsis appliedto high-frequencyelastic wave reverberationsacross the referencesolutions. Windowed space-wave-number processing is thenap- thicknessof a shellhaving nonconcentric surfaces. A previoussummation plied to extractthe abovephenomenology from the referencedata. of backscatteredamplitudes from raysreverberant within concentricsur- facesIS. G. Kargland P. L. Marston,J. Acoust.Soc. Am. 88, 1114-1122 (1990)[is foundto lie on theboundary between stable and unstable reso- nators.Shifting the centerof the innersurface of the shellaway from the directionof the sourceproduces a stableresonator. Rays reverberant be- 8:45 tween suchnonconcentric surfaces produce a far-field focusingthat is periodicin the numberof internalbounces. Exact ray tracing,used to 4uSA3, First circumferential wave in the low-frequency scattering identifyscattered wavefront shapes near focal conditions,reveals the pres- by a viscoelasticcylinder. Farid Chaff,Fernand Leon, and Gfrard enceof gloryrays (off-axis rays which are exactly backscattered). Shifting Maze (Lab.d'Acoust. Ultrason. etd'l•lectron., LADE URA CNRS 1373, the inner surfaceof the shell toward the sourceproduces an unstable Univ. du Havre, Pl. RobertSchuman, 76610 Le Havre, France) resonatorand no focusedrays. The existenceof backscatteringenhance- mentsby focusedreverberant rays for a stableresonator was confirmed Acousticscattering from an absorptivecylinder (Lucite) of infinite with experimentalobservations with elasticscatterers in waterhaving non- lengthexcited by a normalplane acousticwave is investigatedin low concentricspherical surfaces. [Sponsored by the Officeof Naval Re- frequencies.This one is assumedto be homogeneousand isotropicin its search.] viscoelasticproperties. The experimentalresults are obtainedwith a methodof isolationand identification of resonances(MIIR). The resonance 9:30 spectraare particularlystudied. In thegiven frequency range, the presence 4aSA6. Scattering by elastic elliptical cylinders of different aspect of six families of circumferentialwaves labeled 1•, (1 •< l,.•< 6) was noted. ratio. JacquesLanfranchi and G•rard Maze (Lab.d'Acoast. Ultrason. et The resonancesof thesefamilies, except l• = 1, are wide comparedto those d'Electron., LAUE URA CNRS 1373, Univ. du Havre, PI. Robert of aluminumor steel cylinders.Nevertheless, the resonancesof the first Schuman,76610 Le Havre, France) family are easilydetected in the Lucitecylinder, contrary to aluminumor steelcylinders. The scatteringof a plane-wavepulse can be representedby The scatteringof ellipticalcylinders of infinitelength insonified by an the Fourierintegral in orderto determinea theoreticalresonance spectrum incidentbeam perpendicular to their axis is investigated.The methodof withoutchoosing the background.A goodagreement is obtainedfor the isolationand identification of resonances(MIIR) allowsone to plotreso- studiedfrequency range between experimental and theoretical results. In nancespectra. These spectra areobtained fromthree 4 4targ4ets characterized the caseof aluminumor steelcylinders, the computedcalculus in vacuum by their majorradius/minor radius ratio equal to ], 3, T- The resonance are in goodagreement with the experimentalresults. In the caseof the spectraobtained from a circularcylinder excited in the sameconditions Lucitecylinder, that is not verified,particularly with the firstfamily. More- showpeaks related to circumferentialwaves which, for particularfrequen- over, the effectof the externalfluid densityon the resonancesis analyzed. cies, constitutestanding waves. In this case,the phasevelocity depends only on the frequency.Contrary to the circularcylinder, resonance spectra obtainedby an experimentalmonostatic method depend on the azimuthal positionof the transducer.Some resonances vanish at certainpositions. In this case,the phasevelocity and the couplingcoefficient are a functionof the curvatureradius and the frequency.The wavelengthis not identicalon the circumferenceof the ellipticalcylinder. To explainthe experimental 4uSA4. Acousticscattering by a fluid-loadedcylindrical shell with an results,a phase-matchingmodel is developedto determinethe resonance internal plate. AleksanderKlauson, Jaan Metsaveer (Dept. of frequencies[H. '0befall et al.,J. Acoust. Soc. Am. 81, 312-315 0987)]. Mechanics,Tallinn Tech. Univ., Ehitajate tee 5, EE-0026'Fallinn, Estonia), This methodallows one to representthe vibrationstate on the circumfer- Andr6Baillard, Dominique Decultot, and Gfrard Maze (Univ.du Havre, ence.An integralcalculus applied on the latter resultgives the far-field 76610 Le Havre, France) pressure. An experimentaland theoreticalstudy of acousticscattering from a 9:45 fluid-loadedcircular cylindrical shefl with an axiallyattached internal plate is presented.The normallyinsonified stainless-steel shell has an outer to 4aSA7. High-frequency backscatteringby thick finite cylindr'cal innerradius ratio bla = 0.98. A stainless-steelplate of the samethickness shells in water at oblique incidence:Experiments and calculations. is diametricallysoldered, inside the shell,at bothedges along the axis.The ScotE Morse,Philip L. Marston (Phys.Dept., Washington State Univ., object is closedby two flat circularendcaps and is vertically immersedin Pullman,WA 99104-2814), and Gregory Kaduchak (Univ. of Texas,P.O. a watertank (6 taX4 taX3 m). The aim of the studyis to separatethe Box 8029, Austin, TX 78713-8029) effectsof the shell and thoseof the plate and to interpretdifferent sound Variousauthors have demonstrated the importanceof plottingback~ generationmechanisms of the structure.The numericalsimulation is done scatteringamplitude as a functionof bothaspect angle and frequencyfor by the modal expansionmethod using the unstiffenedcylindrical shell thin cylindricalshells in water.Some interestingfeatures of analogous eigenmodes.The shell is taken as infinitely long. The internal plate is plotsfor a thickfinite cylindrical shell with the frequencyrange extending consideredas a line constraintwith the frequency-dependentimpedance. abovethe coincidenceregion have been invesffgated..!m7u!se rcapc, n•c The comparisonbetween theoretical and experimentalresults is achieved measurementstaken with an improvedPVDF sheet source[Kaduchak by an analysisof backscatteredspectra and of arrival times of backscat- et aL, J. Acoust.Soc. Am. 97, 2699-2708 (1995)]reveal a backscattering teredechoes. The scatteringfrom the structuraljoints, the generationand enhancementin thecoincidence frequency region for aspectangles in the transmissionof flexuralwaves through the internalplate, and the interac- vicinityof end-onincidence. Though the cylinder was capped, the features tion betweendifferent vibration forms are observedand analyzed. [Work of interestappear to be identifiedwith waveson the coupledshell-fluid supportedby NATO.] system.Similar features are presentin backscatteringcomputations for a 2544 J. Acoust.Soc. Am., Vol. 99, No.4, Pt.2, April1996 131stMeeting: Acoustical Society of Amedca 2544 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 simply supportedthick cylindricalshell and they may be usefulin high- are forcedto agreesmoothly with the solutionin the near field alonga frequencyinverse scattering. [Sponsored in partby the Officeof Naval curveat a prescribeddistance from the diffractionpoints. An asymptotic Researchand by the UT:ARL IndependentResearch and Development DtN (Dirichlet-to-Neumann)map on thisartificial boundary represents the Program.] effect of the outer domainon the solutionwithin this new boundary.This allowsus to replacethe originalboundary value problem with an asymp- toticallyequivalent boundary value problem, the domain of whichis small and efficientlydiscretized. The methodis applied to diffractionby a 10:00 bluntedwedge, which in thiscontext represents a degenerate prism. The 4aSAg.Strong bending modes for scatteringfrom elasticspheroidal hybridscattering solution shall be comparedto a completeanalytic field solids and shells. Michael E Werby (Naval Res. Lab., Code 7181, representationfound using matched asymptotic expansions. [Work sup- StennisSpace Center, MS 39529) and NatslyA. Sidomvskaia(Univ. of portedby ONR.] New Orleans,New Orleans,LA 70148) 11:00 Bending(flexing) modes are excitedwhen signalsscatter al oblique incidencefrom spheroidal shells [M. Werbyeta/., J. Acoust.Sec. Am. 85, 4aSAll. Acousticalscattering by a density contrast wedge. Arebony 2365 (1989)].This wasinferred by comparingthe exactT-matrix reso- M. J. Davis (Dept. of Math., Univ. of Alabama, Tuscaloosa,AL nancecalculations with thosepredicted from Timoshenko beam theory. A 35487-0350} and Robert W. Scharstein (Univ. of Alabama, Tuscaloosa, moresophisticated approach was alsodeveloped using the generalphase- AL 35487-0286) integralmethod that allowed for nonuniformshapes. The possibilityof the existenceof suchmodes not only for fairly thick shellsbut alsofor thin Considerthe three-dimensionalscattering of a soundpulse generated shellsis considered.Acoustical signals scattered by elasticshells of vari- by an impulsivepoint source and incident upon a penetrablewedge, iden- ousmaterials, aspect ratios and shell thicknessare investigated.The pres- liftedby a densilycontrast. The wavespeed is commonto bothregions and ence of bendingmodes even for very thin shellsis demonstrated.It is the radiationcondition of only outgoingwaves at infinity is appliedin all showed that for thick shells the resonances manifest themselves as maxi- directions.At the boundaryof the wedge there is a pair of transmission mum amplitudereturns while for thin shellsthey manifestthemselves as conditionswhich ensurecontinuity of the acousticpressure and normal minimumamplitude returns. The effect is associatedwith the transitional velocity.By usingFourier transformsin time and parallel to the wedge natureof a rigid-like backgroundto a soft-like backgroundfor the two generatorsand a Kontorovich-Lebedevtransform in the radial direction, extremesso that the return signalsvary in their coherencefrom adding as describedby Jones[Acottstic and ElectromagneticWaves, Oxford constructivelyto adding destructivelyover the thicknessvarialion. The (1986)], boththe exteriorand interiorfields can be obtainedas a sumof sensitivityof resonancelocations as a functionof the elasticparameters is impulsiveterms, some of whichare due to edgediffraction. If the wedge alsopresented. [Work supported by NavalResearch Laboratory and Office angle is a rational fraction of •, then the residueseries can be summed of Naval Research.] and,after careful consideration of whenand where impulsive disturbances can occur,the fieldscan be writtenin remarkablysimple closed forms. This solutionprovides the zero-orderfield for a relativelysmall difference 10:15-10:30 Break in wave speeds. 11:15 10:30 4aSAI2. Backscaltering of obliquely incident plane waves by a 4aSA9. Theory of the scattering of an acoustical signal from an compositecylindrical shell constructedof isotropicand transversely elastic spheroidal shell near reflecting or absorbing interfaces. isotropiclayers. GregoryKaduchak and Charles M. Loeffler (Appl. NatalyA. Sidorovskaia(Dept. of Phys.,Univ. of New Orleans,New Res. Labs., Univ. of Texas,P.O. Box 8029, Austin, TX 78713-8029) Orleans,LA 70148) and Michael E Werby (Naval Res. Lab., Stennis SpaceCenter, MS 39529) Acousticscattering from a transverselyisotropic cylindrical shell ex- cited by an obliquelyincident plane wave is examined.The shellis com- A new formulation that allows one to describe backscattered echoes prised of N layers which may be describedby isotropicor transversely fromelastic shells near pressure release, rigid, and absorbingplaner inter- isotropicmaterial parameters. The presentresearch solves the boundary facesis presented.The proposedformulation is alwaysconsistent--in con- valueproblem for a transverselyisotropic, infinite cylindrical layer within trastto earlier formulations•--evenat low frequenciesand large distances the frameworkof exact 3-D elasticitytheory. The layerswhich comprise from the interface.It allowsfor the rapid reproductionof backscattered the shellare connected via a "propagatormatrix" which relates the interior echoesover frequencyranges of practicalinterest. This novelapproach is andexterior boundary conditions. The backscatteringform functionis then developedand is shownto be sufficientlygeneral to allow for nonreflecting constructedfor severalcommonly used composite materials which display smoothsurfaces. The methodhas been implemented and numerical results transverseisotropy. The resultsfor anisotropicshells are comparedto re- for bothpulse and continuous wave signals scattering from variousshells sultsfound for isotropicshells with similar parameters. Here, attention will arecarried out. The studiesfor variousobject materials, distances from the be givento the similarities(and dissimilarities) of the scatteringmecha- interface,and for the effect that the threetype of interfaceshave on the nismswhich are the chief contributorsto the backscatteringform function detectedsignals are presented. [Work supported by NavalResearch Labo- as the degreeof transverseanisotropy is increased.Analysis of the scat- ratoryand Office of NavalResearch.] teredwaveform through Fourier synlhesis into Ihe time domain will alsobe discussed.[Work supported by ONR.] 10:45 11:30 4aSA10. Diffraction from simple shapes by a hybrid 4aSAI3. Inverse scatteringusing backpropagatedeigenfunctions. T. asymptotic-numerical method. JoshuaM. Montgomery and Paul E. DouglasMast (Dept. of Elec. Eng., Univ. of Rochester,Rochester, NY Barbone (Dept. of Aerospace& Mech. Eng., BostonUniv., Boston,MA 14627), Adrian 1. Nachman (Univ. of Rochester,Rochester, NY 14627), and Robert(?. LYaag (Llnlv.of Rochester,Raahegter. NIY 14627) The applicationof a hybridasymptotic/finite-element method to the A new approachto inversescattering using the eigenfunctionsof scat- problemof scatteringfrom prismatically shaped objects is considered.The tedngoperators is presented.This approachprovides a unifiedframework hybridmethod is basedon patchinga shortwavelength asymptotic expan- that encompasseseigenfunction methods of focussing,diffraction tomog- sionof the scatteredfield to a finite-elementinterpolation of the nearfield. raphy,and inversescattering in arbitrarymedia. The eigenfunctionsof In patching,the diffractedfield shapefunctions with unknownamplitude scatteringoperators are usedto specifysource distributions that focus 2545 d. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society of America 2545 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 incidentenergy in the vicinityof inhomogeneities.The presentinverse tionsof inversescattering. The currently suggested approach has the fur- scatteringapproach represents un 'known scattering media using products of ther advantageof applicabilityto any mediumfor whicha background numericallybackpropagated fields of eigenfunctions.Recent progress in Green'sfunction can be determined.Computational results illustrate fo- the mathematicaltheory of inversescattering has suggestedthat these cussingof eigenfunctionson discreteand distributedscattering media, productsare an appropriatebasis for the reconstructionof unknowninho- quantitativeimaging analogous to diffractiontomography, and high- mogeneities.Because of the focussingproperty of scatteringoperators, resolutioninverse scattering in mediawith stronglyscattering inhomoge- theseproducts also form an efficientbasis for computationalimplementa- neousbackgrounds. THURSDAY MORNING, 16 MAY 1996 MT. RAINIER AND MT. MCKINLEY, 8:30 TO 11:30 A.M. Session 4aSC SpeechCommunication: Potpourri (PosterSession) James M. Hillenbrand, Chair DepartmentSpeech Pathology and Audiology,Western Michigan Universit),,Kalamazoo, Michigan 49008 ContributedPapers All posterswill be on displayfrom 8:30 to 11:30a.m. To allow contributorsan opportunityto see otherposters, contributors of odd-numberedpapers will be at theirposters from 8:30to 10:00a.m. and contributors of even-numberedpapers will be at theirposters from 10:00 to 11:30 a.m. 4aSCI. Temporal coordination of articulator gestures. SidneyA. J. divided into a numberof sections.Vocal tract length as well as section Wood (Dept. of Linguist.,Univ. of Land, Helgonabacken12, 22362 lengthsare determined. To adoptthe model for a malespeaker with a vocal Lund, Sweden) tractlength different from that of the model,the sectionlengths are uni- formlyscaled. To adoptthe model for a femaleor childspeaker, the section Movementdata are analyzedto elucidateprinciples of articulatorco- lengthsare scaled disproportionately over the pharyngeal and oral cavity to ordination.Procedures for trackingarticulator gestures from x-ray motion attainthe speaker'svocal tractlength. The disproportionatescale factors films, and resultsobtained from Swedishand Bulgarianwork are reported arebased on theanatomical data. Accuracy and application of thee•tended in Wood [l. Phon. 19, 281-292 (1991), Proc. 3rd CongressI.C.P.L.A., model are discussed. 191-200,Helsinki (1994), Proc. 13th I.C.Ph.Sc., Vol. I, 392-395, Stock- holm(1995), J. Phon.(in press)].Coarticulation and gesture conflict have beenstudied. The domainof coarticulationhas beenseen variously as a between-targettransition, or comprisingof oneor two phoneroeson either 4aSC3.Acoustic correlates of fricatlvesand affricates. WendyA. side.These are usuallypresented as rival solutions,but the presentdata Castlemanand RandyL. Diehi (Univ. of Texasat Austin,Austin, TX showspeakers using all threeschemes. The pertinentquestion is how does 78713-8029) a speakerselect one of them. For gestureconflict, there are two ap- proaches.The onefeeds all gesturesto themusculature where conflicts are Six adult speakersof AmericanEnglish produced voiceless fricatives resolvedby summingrival forces.The secondmodifies motor input by and affricatesin word initial positionin a carrierphrase, varying vowel queuing antagonisticgestures in order to avoid conflicts.All potential context,and stresspatterns. From eachof the productions,the following gestureconflicts in the presentdata were resolvedby queuinggestures. acoustic measurementswere made: silence duration, frication duration, The data to be reportedhere include Eskimo to providea furthertest on the amplituderise time, amplituderise slope, frieationonset centroid fre- universalityof theseprinciples for articulatorcoordination. [Work sup- portedby SwedishResearch Council for Humanitiesand Social Sciences.] quency,and followingvowel duration.A discriminantfunction analysis revealedthat silenceduration wa• the best at discriminating•twccn the fricativesand affricates, followed by fricationduration, onset frequency, and rise slope.No additionaldiscrimination was found due to either rise 4aSC2. Articulatory model for female and child speakers. T.V. time or vowel duration.The traditionalacoustic measure of rise time, Ananthapadmanabha(Voice and Speech Systems,53, Temple St., whichincludes the duration and the slope of therise, may be dueentirely Malleswaram,Bangalore 560003, India) to thecontribution of theslope rather than the duration itself. Although risc time haslong been considered an importantperceptual cue in the distinc- Articulatorymodels reported in the literatureare generallymeant for a tionbetween fricatives and affricates, recent research has brought this into prototypemale speaker.One suchpopular model is that proposedby Mer- question[K. R. Kluenderand M. A. Walsh,Percept. Psychophys. 51, melstein[J. Acoust.Soc. Am. 53, 1070-1083(1973)]. In thispaper the 328-333 (1992)].The results of thisstudy suggest that duration measure- scopeof Mermelstein'smodel is extendedto adoptit for anymale speaker ments(preceding silence inlerval and frication duration) are more salient as well as for femaleand child speakers.The defaultvocal tract shape of acousticcorrelates than amplitude rise-time measures. [Work supported by the modelfor a givenvowel is determined.The axis of the vocaltract is NIDCD.] 2546 d.Acoust. Soc. Am., Vol. 99, No.4, Pt.2, April1996 131stMeeting: Acoustical Society of America 2546 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 4aSC4. Abstract withdrawn. amongseveral factors, however. indicate that the perceptual improvements from speakingclearly depend on the speaker,vowel categoryand subse- quentconsonantal context. 4aSC5. Study of the acoustic-to-articulatorytransformation for vowels and fricatives. Edward L. Riegelsbergerand Ashok K. Krishnamurthy(Dept. of Elec.Eng., Ohio State Univ., 2015 Nell Ave., 4aSC8. Prosody as a potential cue for age perception. JamesV. Columbus.OH 43210) Ralston,George Fidas (Dept. of Psych.,Ithaca College, Ithaca, NY 14850},Christin E. Agli, and ColleenCoppola (ithacaCollege, NY 14850) Usingsynthetic speech from an articulatoryspeech synthesizer, statis- tics are generatedof the error betweenactual articulatory configurations Previousresearch has shown that relativelylocalized acoustic informa- andthose estimated by an acoustic-to-articulatorymapping routine. Based tion, suchas voice pitch,fi} perturbation,and hoarsenessare cuesto age solelyon acoustics,neglecling aerodynamic and perceptualissues, histo- perception.The presentstudies examined the potentialrole of sentence- gramsof totalestimation error suggest that the inverseproblem is no more level prosodicinformation in the perceptionof age. Sixteendift•rent six- ambiguousfor fricativesthan for vowels. By examiningthe error covari- word sentenceswere recordedfrom eight different malesin each of three ance,dominant articulatory dimensions are identified in thefricative model agegroups (middle school sludents, college students, and senior citizens}. that have the greatesteffect on the acoustictransfer function and, as a Several acousticmeasurements were made of each sentence,including result,are better estimated by theacoustic-to-articulatory mapping routine. meanfrequency, slope of intonationcontour across entire sentence,slope Weak articulatory dimensionsare also found that the acoustic-to- of terminalfall, andamount of inflection(i.e., absolute frequency change articulatorymapping routine can barelyestimate better than simply guess- summedacross the sentence).A secondset of sentenceswas constructed ing. Suggestionsare made for ways in which these error statistics,and by randomlyreordering the wordsin eachsentence. Original sentences and specificallythe knowledgeof the unequalimportance of differentarticu- their scrambledcounterparts were presentedto 19 listenerswho ratedthe latorydimensions, can be usedto motivateimproved techniques for the agein yearsof thespeaker of eachsentence. Analyses of variancerevealed acoustic-to-articulalorymapping of speech.Demonstrations of some of thatage judgments were less extreme for scrambledsentences as compared theseideas will begiven on real and synthetic speech. [Work supported by to the regularsentences, particularly for the college-agedand elder voices. theAFOSR.] These resultssuggest that the scramblingaltered sentence-levelvocal in- formation.Preliminary regression analyses also indicate that perceived age is relatedto somerelatively global acoustic measures, such as amountof inflection. 4aSC6. Fundamental frequency in minimal pair sentences. I.D. Trout (PhilosophyDept. and the ParmlyHearing Inst., LoyolaUniv. of Chicago.6525 N. SheridanRd., Chicago,IL 60626) 4aSC9. Rounding and palatalization convergencein Twi. KennethJ. de Jongand Samuel Gyasi Obeng (Dept.of Linguist.,322 MemorialHall, The declinationof fundamentalfrequency was investigatedin minimal IndianaUniv., Bloomington,IN 47403) pair sentenceswhich soundalike but which haveword boundariesin dif- ferent positions{•e.g., The monkeyraces it/The monk erasesit). Early This paper reports an acoustic and articulatory study of labio- resultssuggest that fundamentalfrequency declines over these minimal palatalizationin Twi Akan (WestAfrican). Labio-palatalization is rare pair sentencesin accordancewith the resultsreported on globaldeclination cross-linguistically,as would be predictedfrom theoriesof vowel disper- effectsif'Hart et al., A PerceptualStudy of Intonation(Cambridge U. P., sion,since palatalization and labializationhave opposite effects on second New York, 1990)].Baseline fundamental frequency over sentences will be formanlfrequency. Labio-palalalizafion in Twi, however,is the ongoing comparedto that for wordboundaries in two-wordsequences {e.g., mon- result of a convergenceof contrastireconsonant rounding and vowel- keyraces/monk erases) excised from those minimal pair sentences. Further inducedpalatalization which have been functionally combined in certain analysiswill determinewhether local properties of fundamentalfrequency segments.Preliminary palatographic data indicatethat roundedcoronal movementand accelerationdiffer significantlyin word boundaryversus consonantshave more posteriorcoronal constrictions. Present acoustic intrawordposition, and .so whether such properties may acl as a localcue analysesshow rounded consonants to be markedby a loweringof F3. to wordboundary. [Work supported by NIDCD ProgramProject Grant.] Combiningcoronal retraction and rounding,thus has two effects.(I) It producesa stableregion of low F3, as indicatedby nomogramsin Wood 0986}. (2) It increasesfront cavity length, resulling in a lowerand more compactspectrum of consonantalfrication noise. Thus l) examiningthe 4aSC7. Effects of "clear speech" on duration-dependentvowel role of uncommoncontrasts in a phonetalcsystem can shedlight on pos- contrasts. Jean L. DeMerit (Linguist.Dept., Univ. of Wisconsin-- ttedmechanisms for languagechange, and 2) roundingmay serve different Madison, 1220 Linden Dr., Madison, WI 53706) rolesin differentlanguage systems, to lower both front and back-cavity resonances,or a more specificrole of loweringfront-cavity resonances which shapeconsonantal noise. Acousticand perceptual effects of "clearspeech" were investigated by focusingon two duration-dependentvowel contrasts in AmericanEnglish, le, &eland IA, P•. Minimal pairsof wordswere recordedin carriersentences by four nativefemale speakers under two speechstyle conditions, conver- 4aSCI0. The acquisition of lhiwanese (Amoy) initial stops. sationaland clear. Measurements of vowel durationand formantfrequency Ho-hsienPan (Dept.of ForeignLanguages and Literature, Chiao Tung were made.The acousticanalyses revealed patterns of durationalbehavior Univ., Hsinchu, 30050, Taiwan) that differed by speakerbut were generallyuniform acrossboth vowel contrasts.FI and V2 frequenciesfrom the groupeddata were displaced Taiwanese(Amoy) is oneof thefew Chinesedialects with a three-way towardmore peripheral regions of the vowel spacein clearspeech. How- contrast.There are threeTaiwanese syllable initial voicelessunaspirated ever, no consistentpatterning was evidentacross individual speakers. A stops,/p,t,k/, three voiceless aspirated stops, /ph, th,kh/, and two voiced perceptualtest using gored speech stimuli from two of the speakerswas stops,/b,g/. This paperreports on two studiesof the acquisitionof the usedto assessthe relativeamount of acousticsignal required to identify voicingcontrast in Taiwanese.The longitudinalstudy followed two girls eachvowel per speechstyle. Also, vowel identification rates were exam- from about28 monthsto 33 monthsand to 40 months,respectively. The inedfor initial gatedsegments (which included the first 25 ms of the cross-sectionalstudy compared VOTs in 54 childrenranging from 30 vowel}as well as for full wordpresentation. Statistical analyses showed monthsto 6 years.In thelongitudinal study, the children had already begun significanteffecls of speechstyle on vowel identification.Interactions to acquirethe contrast between the two voiceless stop lypes in thebegin- 2547 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April1996 131st Meeting:Acoustical Society of America 2547 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 ningof recording,although there were still manytokens of voicelessas- often in the sentencecondition. Acoustical analysis indicated that some, piratedstops produced with sbort lag VOTs. Later, the VOTs of thevoice- but not all, of the variationin assimilationpatterns could be explainedby lessaspirated stops were hyperaspirated with VOTs exceedingthe adult F1/F2 variation.Implications for JapaneseL2 learnersof Englishare dis- norm, and there were fewer tokenswith shortlag VOTs. Both children cussed.[Work supported by NIDCD.] beganto acquirethe voicedstops around 33 months.The cross-sectional studyconfirm Kewley-Port and Preston's (1974) claim and shows further that6-year-olds' production of voicedstops is not completelyadult-like. 4aSC14. Response complexity effects on vocal reaction time in normalaged speakers. Michael S. Fozoand Ben C. Watson (Dept.of Otolaryngol.,Rm. 171 Munger Bldg., New York Medical College, 4aSCII. The consonantalproperties of the unrounded high-mid Valhalla,NY 10595) back vowel/v/in Mandarin Chinese. Jie Zhang (Dept.of Linguist. Univ. of California,Los Angeles,405 HilgardAve., Los Angeles,CA Reactiontime (RT) studiesreveal that vocal responsespresent an ex- 90095) ceptionto the pervasivefinding of slowedperformance in agedadults. Previousvocal RT studiesthat compared young and aged speakers elicited The vowel /x/ in Mandarin has traditionally been documentedas a a single-wordresponse. Inconsistent findings may be altributedto theiruse simplevowel although it hasbeen noticed to involvemore complicated of a limitedrange of responsecomplexity. Young speakers show a signifi- articulatormovements in its productionthan a monophthong.Three male cantincrease in vocalRT fromvowel to sentenceresponses [Watson et al., speakersof BeijingMandarin were recorded for an acousticstudy of this J. Voice 5, 18-28 (1991)]. This studytested the hypothesisthat aged vowel.The frequency and eni:rgy values of Fl throughF4 of thebeginning speakersin goodphysiologic condition show significantly longer vocal RT part (around20 ms), the first quarter,and the restof the vowelwere valuesrelative to young •peakersas responsesincrease in complexity. measuredfrom the spectrogramand LPC usingCSL. Resultsof two-tail Vocal RT was recordedfor isolated vowel, word, and sentenceresponses. pairedt testsshow that the firstquarter of the vowelhas significantly The simpleRT paradigmincluded variable foreperiods and intertrial inter- weakerenergy in F2 throughF4 thanthe rest of thevowel at p = 0.05 level, vals.Young subjects ranged from 24-31 yr. Aged subjectsranged from indicatingapproximanflike properties in thispart. Also, the initial 20 msof 68-85 yr. Group,response, and group x responseeffects were significant. thevowel has higher FI andlower F2 thanthe following part, indicating Posthoc comparisons revealed significant between-group vocal RT differ- a possiblepharyngeal constriction. So phonetically,h# consistsof a very encesfor the wordand sentence responses. Consideration of peripheraland shortpharyngeal approximant [•], a velarapproximant [•], anda real centralfactors that may underlie the responsecomplexity effect on vocal vowel [•r] in sequence.This phoneticcharacteristic accounts for the fact RT in agedspeakers supports the conclusionthat the originof the com- that glottalstop insertion before a syllable-initial/•/is muchless likely plexity eftbetresides in centrallinguistic and/or motor planning for the thanthat before a real onsetlessmonophthong/aL but patternswith that response. beforea syllable-initial/wo/. 4aSC15. The effects of the attenuation of second and third formant 4aSC12. Perception of English /r,l,n,d/ by native speakers of frequencieson the recognitionof stop consonantvowel syllablesin Chinese. Anna Marie Schmidt (Schoolof SpeechPathok and Audiol., aphasic and nonaphasicsubjects. Lyn Goldberg (American P.O. Box 5190, Kent StateUniv., Kent, OH 44242) Speech-Language-HearingAssociation, 10801 Rockville Pike, Rockville, MD 20852) Speakersof somesouthern dialects of Chinesedo notmake a distinc- tion between/n/and/1/in Chinese.Previous pilot researchindicated that The effectsof the attenuationof secondand third formantfrequencies they also havedifficulty with this distinctionboth perceptuallyand pro- on the recognitionof stopconsonant vowel syllables (/p,b,t,d,k,g/paired ductivelyin English.As a basisfor an experimentin trainingthis distinc- with the vowel/el) in fluentand nonfluentaphasic and nonaphasicnormal tion, a closerexploration of thesespeakers' perception of Englishwas subjectswere examined.Statistical analyses revealed significant differ- performed.This studyexamined these speakers' perception of English encesbetween groups, between formant conditions, and betweenstop con- Ir,l,n,d/. Five nativeChinese speakers heard English words from minimally sonants.All groupsresponded similarly under the formantconditions, but differentsets produced by threenative English speakers and labeledthe the attenuationof F2 appearedto accountfor the moststriking disparity firstconsonant of eachword. Native English speakers labeled the same sets betweenconsonant recognition scores irrespective of group.A seriesof with highaccuracy. Results and implications for trainingwill be presented. confusionmatrices showed that confusionsmade by aphasicsubjects in- volvedboth place of articulationand voicing errors, particularly for non- fluentaphasics, and involved the substitutionof moreanterior consonants. Importantcues for the voicingof anteriorconsonants appeared to be car- 4aSCI3. Effects of speech style on the perceptual assimilation of ried by F2. The finding that more intact speechproduction abilities ap- American English vowelsby Japanesespeakers. Reiko A. Yamads pearedto facilitate more accuratespeech recognition was interpretedas (ATR, 2-2, Hikaridai, Seika-cho, Soraku-gun, Kyoto 619-02 Japan), supportfor the motortheory of speechperception. WinifredStrange, Brett H. Fitzgerald (Univ.of SouthFlorida, Tampa, FL 33620), and Rieko Kubo (Nara, 631 Japan) Of specificinterest in this studywas the extentto which speechstyle 4aSC16. Lexical stress perception by hearing-impaired listeners. (citationform versussentence form) aft•.ctedperceptual assimilation of AE DraganaBarac-Cikoja and Sally Revoile (Ctr. for Auditoryand Speech vowels by Japaneselisteners. Four adult male speakersproduced l I AE Sciences,Gallaudet Univ., Washington, DC 20002) vowelsin/hVba/bisyllables in bothcitation form (lists)and in the sen- renee"I hear the/hVb/on the tape."Response categories, designated in Identification of lexical stress in VCVs isolated from sentences was Katakanasymbols, included five shortvowels, five longvowels, and eight studiedfor moderatelyto profoundlybearing-impaired listeners. Two fac- vowelcombinations (e.g., on, el, ja:). Twenty-fourJapanese listeners se- tors,sentential stress position and speech rate, were manipulated separately lectedthe responsecategory which was most similarto the/hV/syllable in the productionof "You put VCV to bed." When sententialstress was they heardand ratedits "goodnessof fit." Resultsindicated that, in gen- manipulated,each of: you, put, VCV, bed, was stressed.When speechrate eral, AE vowels were assimilatedto the Japanesevowel categoryclosest in (fast and slow) was manipulated,the VCVs were from sentenceswith articulatoryvowel space.However, intrinsic duration information was uti- stresson the VCV only. Twenty VCVs for each speechrate and ten VCVs lized much more consistentlywhen the syllableswere embeddedin a for eachsentential stress position were tested. Hearing-impaired (n-33) carriersentence. That is, intrinsicallylong (or diphthongized)AE vowels and normal-bearinglisteners (n=8) identifiedwhether the VC or the CV were assimilatedto long-vowelor two-vowelresponse categories more was stressed.In contrastto the normal-hearinglisteners, lexical stress 2548 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society of America 2548 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 identificationby the hearing-impairedlisteners was significantlyreduced deviatingsignificantly from the normalcases have been noted in the voice for the fast speechrate. Both listenergroups showed the sameeffect of sourcesignal. For example.occurrence of doublepeak duringthe open sententialstress location: Performance was best when emphasis was on the phase.prolongation of the intervalnear glottal air flow peak.absence of VCV, andworst when either constituent adjacent to the VCV wasempha- clearlydefined negative peak near epoch. etc. Interpretationof the voice ,,ized. Results will be discussed with reference to the acoustic conse- sourcesignal in termsof thevocal fold vibratorypattern and pathology has quencesof theproduction constraints and the accessibility of the prosodic beenattempted. Such an interpretationis validatedagainst direct laryngo- cuesto the hearing-impairedsubjects as predictedby severalaudiological andpsychoacoustic variables. [Work supported by NIH andthe Gallaudet scopicobservation where ever available. This on-goingstudy suggests the Researchlnstitule.] possibilityof differentialdiagnosis of the vocalfold pathologyby acoustic analysisof vowel sound. 4aSC17. Comparison of Caseygrams for normal and pathological speech. P. G. Vaidya (Schoolof Mech. and Mater. Eng., Washington 4aSC20. Analysis of "cold-affected" speech for inclusion in speaker State Univ., Pullman.WA 99164). Alison Behrman (Hunter College. recognitionsystems. RenettaG. Tull (CommunicationsSciences and CUNY. New York.NY}, C. R. Winkel (WashingtonState Univ., Pullman, Disorders Dept.. NorthwesternUniv., Evanston. IL) and Janet C. WA 99164}, and Sally Alforde (Latah Health Services,Moscow, ID Rutledge (NorthwesternUniv., Evanston.IL 60208-3118) 83843) In this paper,vowel soundsproduced by healthyspeakers and those Parametersof speechproduced during winter weather are analyzedto producedby speakerssuffering from certainpathologies are compared determinethe potentialinfluence of distortedvoices due to commoncold usingdifferential trans-spectrograms. or the "Caseygrams."These Casey- on automaticspeaker recognition systems. This researchexamines speech gramsare generaledas follows:First, the vowel soundsamples are opli- recordedbefore, during. and after bouts wilh the commoncold. "Cold- reallyreconstructed to reduceleakage errors. The dataare thenpartitioned affected"speech shows noticeable acoustic and phoneticdifferences be- into manysmaller samples. Each of theseis transformedinto the frequency tween test sessions.Examining the different statesof one male speaker's domain.These FFrs are usedto calculatetwo different types of trans- voice allows an opportunityto addressthe speakerintersession problem spectralcoherences (TSCs). [Please see Vaidya and Anderson, J. Acoust. that existsin speakerrecognition technology. Specific emphasis is placed Soc.Am. 89. 2370-2378(1991}.] These two TSCs are specifically devel- opedto measurethe interactionof the main harmonicswith the subhar- on the contrastsin varioussessions of T[MIT inspiredsentence "She had monics.Positive results in thisdifferential trans-spectrogram (Caseygram) your dark suit in greasywash water all year." It also analyzesphonetic indicatethat chaos is present,either in a nascentstate or fully developed contrastsand looksat differencesin formantpatterns. Phonetic transcrip- state.It is expectedthat these Caseygrams would give an earlywarning of tionsof "cold" and "normal" sessionsreflect changes in placeof articu- impendingdisorders and wouldalso help monitorrecovery from disorders lation. Perceptualand acousticanalyses reveal pausesand epentbeticsyl- suchas damageto the speechcenter of the brain followinga stroke. lablesthai are not constantthroughout all sessions."Cold-speech" also producesnoise caused by hoarsehessand coughing.Research presented hereshows evidence of variabilitybeyond "normal" speech patterns. Con- tributingto the informationon intraspeakervariability, this work provides 4aSC18. Optimization for source waveform synthesisof pathological voices. BrianC. Gabelman,iody Kreiman,Brace Gerratt (VoiceLab., a preliminaryanalysis of "cold-affected"speech in an effort to include Div. of Head/NeckSurgery, UCLA, 31-24 Rehab.Ctr., Los Angeles,CA "abnormal"speech and speechaffected by communicationsdisorders into 90095-1794),and Abeer AIwan (UCLA. LosAngeles, CA 90095-1794) the frameworkof automaticspeaker recognition. Thispaper describes an algorithmthat fits analytical source models of Ibe glottalvolume velocity to glottal sourcewaveforms from inverse- filteredvowels. The analyticalmodels include the KGLOTFg8, LF, and 4aSC21.Analysis of the glottal excitationof intoxicatedversus sober simplifiedLF [Qi andBi, J. Acoust.Sue. Am. 96. 1182-I185(1994}]. In speech:A first report. KathleenE. Cummings (Digital Signal the firststage of thealgorithm, curve features (peak values, zero crossing. ProcessingLab., School of ECE,Georgia Tech, Atlanta, GA 30332-0250). period,etc.} are automaticallyextracted from samplesof pathological StevenB. Chin, and David B. Pisoni (Indiana Univ., Bloomington,IN voicesand least-squaresfitting is performed.The parametersare thenfine- 47405-1301) tunedbased on the perceptualquality of the synlhesizedvoices. Goodness of approximationof the resultantsource function is determinedby pereep- tuallycoraparing the final synthesizedvowel soundsto the originalsound. The objectiveof the researchreported here was to performan analysis Limitationsof currentsource models with respectto modelingpathological of the voicingcharacteristics of soberand intoxicatedspeech in orderto voicewill be discussed.[Work supported by NIDCD.] assessthe possibilityof detectingintoxication from the speechsignal. Becausethe glottalexcitation is the resultof complicatedand intricate motionsby the vocalfolds, it shouldbe significantlyaffected by alcohol use.In thisstudy. excitation parameters were extracted from non-nasalized 4aSC19. Acoustic characteristics of voice source for pathological vowelsin eightutterances spoken in bothsober nod intoxicated conditions voices: Some case studies. T V. Ananthapadmanabha(Voice and SpeechSystems, 53, TempleSt., Malleswaram, Bangalore 560003, India), by four speakers.Fifteen parameters,including pitch, pitch contour,rms B. Mallikarjun,and Dipti Mallikarjun (The PearsSpeech & HearingCtr., intensitymeasures, and measuresof shimmerand jitter. wereextracted Ellisbridge,Pritamnagar, Ahmedabad 380 006, India} directlyfrom the speechwaveform. As expected,the mostsignificant dif- ferencesbetween sober and intoxicatedspeech were in parametersmea- The aim of thisstudy is to examinethe voicesource signal of patho- suringperturbations in adjacentpitch periods. Also as expected, there were logicalvoices. Pathological cases of vocalnodules, polyps, paralysis, ma- nosignificant differences in moreglobal parameters such as average pitch. lignancy,and laryngitishave been investigated.Some pre- and postopera- Additionally,glottal waveforms were extracted from two of the speakersin tive caseshave alsobeen studied.The sustainedvowel/a/of the subject both conditionsusing an adaptationof Wong'sclosed-phase glottal hasbeen recorded. The acousticsignal has been analyzed using an inverse filteringtechnique to obtainthe voicesource signal (derivative of glottal inverse-filteringmethod. Again, the mostsignificant differences between air flow}.The voice sourcesignal is displayedand markedfor detailed soberand intoxicatedglottal excitationwere found in pitch-period-to- examination.Acoustic recording, analysis, and marking is done usinga piteh-periodvariability. [Supported by a grantfrom the Alcoholic Bever- VAGHMI system.For each type of pathology,certain consistent features ageMedical Research Foundation to IndianaUniversity.] 2549 d. Acoust.Soc. Am., VoL99, No. 4, Pt. 2, Apdl lg96 131stMeeting: Acoustical Society of Amedca 2549 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 4aSC22. Speech motor coordinationin children with phonelogical 4aSC25. The McGurk effect for non-native speechsounds perceived disorders. Marius Fourakis,Ying Xu, and Jan Edwards (Dept. of as nonspeech. Lawrence Brancazio (Haskins Labs., 270 Crown St.. Speechand HearingSci., The Ohio StateUniv., Columbus.OH 43210) New Haven. CT 06511 and Univ. of Connecticut) The McGurk effect--the integrationof xisual informationinto speech This studyexamined the questionof whetherchildren with phonologi- perception--is well documentedtbr English consonants.However, a re- cal disordershave problemsin speechmotor coordination.Four children centattempt to extendthe effect to musicalevents (violin plucks and bows) with phonologicaldisorders. four typicallydeveloping children matched showedonly a weak visualinfluence on percepttoo[Saidaria and Rosen- for age and gender,and four adultswere askedto say multiplerepetitions blum, Percept.Psychephys. 54, 406-416 (1993)]. Thus the conditions of "bad dog" at normaland fast ratesof speech.The productionswere requiredto producea strongMcGurk effect are unknown.The effect may digitizedand tbrmant tracks were obtained using LPC analysis.Standard be specificto perceptionof nativephonelogical categories; alternatively, it deviationswere calculatedover the second-fermentvalues frame by frame may applyto dynatnicvocal-tract event• in general.This studytested for a MeGark effect with click consonants.•hich are phonelogicalin some alongthe four 50-ms spans of theCV andVC transitions.The F2 tracksof Africanlanguages, but are treated as nonspeech by Englishspeakers [Best, the adultswere much less variable than those of bothgroups of children. McRoberts,and Sithole.JEP:HPP 14, 345 360 (1988)]. Audiobilabial, The F2 tracksof the phonelogicallydisordered children were more vari dental, and lateral clicks, spokenin isolationand coarticulatedwith a able than thoseof their typical age peersfor threeof the four transitions; vowel,were dubbed onto video presentations of eachclick. Parallel stimuli however,the F2 tracksof the phonelogicallydisordered children were less were made t¾olnEnglish stopsin syllablesand with their excisedbursts variablethan their age peersfol the initial "be" transition,the only tran- only. English-speakingsubjects made bimodal matching judgments on the sitionin whichthe tonguewas not involvedin both the consonantand the dubbedstimuli. Resultsrevealed a visual influenceon perceptionof the vowel articulation.This re.suitsuggests that children with phonelogical non-nativesounds that was somewhatweaker than for native speech,al- diseldersmay have difficulty in rapidly sequencinggestures that involve thoughstronger than Saidariaand Rosenblum'seffect for violin sounds. [Worksupported by N1H.] conflictingconfiguratious for the samearficulator. 4aSC26. Speakers' production of word frequency according to 4aSC23. A numerical measureof alcohol depression. Harb. S. Hayre semantic and pragmatic contexts and to a production versus (hnpairmcnt Measures. Inc., 10405 Town and Country Way #203, perception representation. Jan Charles-Luce, Kristin R. Dolena, Houston, TX 77024- I 100) Lottie Chappell,and Kelly M. Dressier (LanguageProduction Lab., Dept. of Communicative Disorders and Sciences. Park Hall. Univ. at Buff:ale, Consumptionof alcoholicbeverage is saidto causedepression which is Buffalo, NY 14260) then followed by a high.A literaturereview showsthat thi,;depression had It hasbeen shownthat speakersadjust their articulationaccording to not been measurednumerically. Chemical impairmentmeasure (CMI) the amountof semanticall•biasing information in the whole utterance. based on speechwas used by the author to detect and measurethe Furthermore.subjects modify their speechproduction for the benefitof a physiological/neurologicaldepression. CMI rangesfront zero to threeon a listener.In the presentinvestigation, speakers' production of high- and specialscale. Twenty subjects were given a doubledrink of whiskeyeach, 1ow-lYequencywords was examined when produced in two semanticcon- and their CMI were measuredat 2 rain intervalsstarting 2 min prior to texts(semantically biasing and semantically neutral) and in two pragmatic alcoholingestion and continuedfor 60 rain thereafter.CMI, in all cases contexts(presence or absenceof an overtlistener). In addition.speakers was observedto initially decreaseto a minimum,then monotonicall5in- were instructedto producethe targetwords in a productionmode versus a creaseto a maximum,and eventuallydecrease thereafter until it reachesa perceptionmode of experience.For example,speakers were instructedto value near the predrink value. The time to reachthe minimum as well as interpretthe words accordingto how frequentlythey "say" the word or how frequently they "hear" the word. The resultsof acousticmeasure- the depththereof varied from one personto the next verifyingthe t•ct that ments showedthat subjects'production of high- versuslow-frequency each personhas their own tolerancelevel. words was affected by the semanticand pragmaticcontexts. However. subjectsmodified their articulationdifferently depending on the modeof experiencein which they interpretedthe words' frequency.These results will be discussedaccording to pragmaticcompensation and semanticac- tivationin speechproduction and. in particular,how speechproduction 4aSC24. Effects of syllable duration on stop-glide perception by may be affectedby the speakers'representation of lexicalitems according humans and monkeys. Joan M. Sinnott, Charles H. Brown, and Kelly to theirproduction versus perception mode of experience.[Work supported W. Moslelief {Comparativetlearing Lab., Psych. Dept., Univ. of South by NIDCD.] Alabama, Mobile, AL 36688) Humansand monkeyswere comparedin their perceptionof phoneme 4aSC27. A study of lecture and computer-based teaching of boundaryshifts along two syntheticstop-glide/bet-wed continua differing articulatory and acoustic aspects of American English vowels. in overallsyllable duration (150 vs 320 rns).Humans were firsl tested with William D. Clarke III (Dept. of CommunicationSciences and Disorders. a written identificationprocedure and showeda boundaryshift to longer lJniv. of S. Florida, Tampa, FL) transitiondurations with increasedsyllable duration. as previously reported in the literature. Humans and monkeyswere then tested with a low- Studentsin introductorycourses on speechscience have considerable uncertaintydiscrimination procedure but showed little evidence of a difficultyin understandingthe articulatoryand acoustic phonetics involved sensory-leveldiscontinnity underlying the identified boundaries:Instead in the productionof vowels.A computer-basedcourse of instructionhas sensitivitytended to [bllow Weber's law. Finally, both humansand loon- been developedthai is intendedto increasestudents' understanding of the interrelationshipsof the importantconcepts in Thisdifficult area [lackson keys were tested with a gelno-go identification procedure specifically et at., I. Acoust.Sec. Am. 95, 3014lA) 0994)]. The presentexperiment designedfor monkeys.Similar stop-glideboundaries emerged and shifted evaluatedthe computer-hascdexerci•s along with the traditionallecture with increasedsyllable duration for bothspecies, indicating that monkeys method.Students were assignedto two groups,and each group received makegood models of humanstop-glide sensitivity in identificationproce- boththe lecture and computer instruction but in a differentorder. Cognitive duresthat involvehigher level attemionaland memorial processes. [W•rk structurestests using similarity ratings were administeredto assessstu- •upportedby NIDCD.] dents'understanding of the materialbefore and after each type of instrue- 2550 J. Acoust.Soc. Am., Vol. 99, No.4, Pt. 2, April1996 131st Meeting:Acoustical Society of America 2550 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 tion. Twentyconcepts from the disciplinesof articulatoryand acoustic hereusing the head-turnpreference procedure. A groupof infantsubjects phoneticsof vowelswere paired for similarityratings. Students' mental (age 6 months)was presenteddiatonic melodic sequences, identical in modelswere compared to thoseof expertsusing "Pathfinder" network, duration,tempo, and intervalliedistance, that either reachedharmonic multidimensionalscaling, and profilecorrelations. The students'shift to- closure(closed) or did not(open). Six closed-openpairs were constructed ward expert-likepatterns was small after lecture-onlyor computer-only by matchingsequences for pitchcontour. The sequenceswere presented in presentations.The shift was moderatewhen the computerwas first and a random order, and orientationtimes to each sequencewere recorded. lecturewas second.The shift was largewhen the lecturewas followedby Surprisingly,6-month-olds revealed a significantpreference for the har- the computer. monicallyopen melodic sequences. An additionalstudy examines whether 9-month-oldsexhibit a reversalof this preference,or whetherharmonic incompletenesscontinues to recruitattentional processes. These findings 4aSC28. Perceptions of music and speech based on the are consideredin light of the child's growing experiencewith Western autocorrelation and interaural cross-correlation functions. Yoichi tonalmusic, and auditory-perceptualreorganizations that may occurduring Ando (Graduate School of Sci. and Technol., Kobe Univ., Rokkodai, the latterhalf of the firstyear in musicand speech. [Work supported by Nada, Kobe 657, Japan) NIDCD.] Basedupon a modelof auditorypathways which consists of the auto- correlationand the interauralcross-correlation mechanisms fAndo, Con- cert Hall Acoustics(Springer-Verlag, New York, 1985)],perceptions of 4aSC30, Gestural overlap analysisof lenis stop reduction in Korean. musicand speechas well as subjectiveresponses of soundfield in rooms are well described.This paperreviews some subjective attributes from Sook-hyangLee (Dept. of EnglishLanguage and Literature,Wonkwang recentinvestigations. The factorsextracted from the autocorrelationfunc- Univ., lksan, Korea 570-749) tion(ACF) of sourcesignals include: (1) theenergy of soundsignal; (2) the effectiveduration of the normalizedACF; and (3) peaksas a functionof its Koreanlenis stops have been reported to becomevoiced intervocali- delay.These factors are deeply related to (1) loudness,(2) subjectiveat- cally (Kagaya,1974) and are often reduced to sonorantsin casualspeech tributesof thetemporal structure of soundfield, (3) themissing fundamen- with differentdegrees of reductiondepending on the placeof articulation tal of complexsounds, respectively. Factors which may be extracted from (Lee, 1995).Velar lenis stops are more often reduced than the labialsand the interauralcross-correlation function are included:(1) the IACC, the coronals,which makessense from the point of view of articulatorypho- maximumvalue in therange of the interauraldelay time; (2) r•ACC,the nology(Browman and Goldstein, 1990). The oral gesture for a velarstop delayof theIACC; (3) Wl^cc,the width of IACC. The firstfactor well ison the same vocal tract tier (tongue body tier) as the neighboring vowels, describesthe clarityof speechas well as subjectivepreference of sound field. The secondfactor may be relatedto the apparentsource width so it shouldbe more affectedby overlap and blendingwith the vowel (ASW), and the last one is relatedto the image shift of soundsource. gesturesthan the closure gestures for other stops. This study investigates in what vowel environmentslenis stop closureshows the most reduction. /VCV/tokens in carrier sentenceswere recordedand acousticanalysis was done.The resultsshowed that generally, reducing lenis stop closure is most 4aSC29. Infant preference for harmonic closure in musical in theenvironment of precedingand following low vowels,and least in the sequences.Michael L. Tucker,J. David Smith, and PeterW. Jusczyk environmentof highvowels, where the tonguebody gestures of neighbor- (Dept.of Psych.,SUNY, Park Hall, Buffalo, NY 14260) ingvowels are more compatible with the stop's gesture. Labials, especially Previousinvestigations of Western tonal sensitivity suggest that young whenthey are in the highrounded vowel environment, showed a larger infantsmay haverudimentary tonal knowledge, for they noticealtered amountof reduction,which makes sense from the pointof view of articu- notesand chords in a varietyof change/no-changediscrimination tasks. In latoryphonology, since one of theoral gestures for a labialstop is on the contrast,infants' preference for differenttonal structures was evaluated samevocal tract tier, lip tier,as the surroundingrounded vowels. THURSDAY MORNING, 16 MAY 1996 REGENCY D, 8:00 TO 11:45 A.M. Session 4aUW UnderwaterAcoustics: Visualization of AcousticPropagation Mechanisms Shira L. Broschat, Chair Schoolof ElectricalEngineering and Computer Science, Washington State University, Pullman, Washington 99164-2752 Chair's Introduction--8:00 Invited Papers 8:05 4aUWI,Criteria and examples of the use of visualization in underwater acoustics. R.A. Zingarelli and S. A. Chin-Bing (Naval Res.Lab., Acoust. Simulation Section, Stcnnis Space Center, MS 39529) Visualizationin underwater acoustics is a relativelynew field, with a peculiarset of promisesand pitfalls. Advanced computer graphicscan provide insight into physical processes, butonly if thetools are simple and flexible enough to provide'on the fly' visualizationasthe research isbeing done. Furthermore, 'reality checks' against standard benchmark solutions must be performed at everyopportunity. Here, examples arepresented ofutilitarian visualization fortime-domain sound propagation, howthese are checked againstreference solutions, aswell as some interesting cases where these checks were not made. [Work supported byONR.] 2551 J. Acoust.Soc. Am., Vol. 99, No.4, Pt.2, April1996 131stMeeting: Acoustical Society of America 2551 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 4aUW2.B•tt•minteracti•ns•fpulsepr•pagati•nande•rrespondingreal-timereverberati•n.KeririB. Smith (Dept.of Phys., CodePH/Sk, Naval Postgrad. School, Monterey, CA 93943) A simple,memory-intensive algorithm using a split-stepFourier cw PEmodel to computethe time-domain animation of a pulse hasbeen developed. By examiningsuch an animation in thepresence of a rough,deep ocean bottom, the significance of secondary multipathson predicted reverberation returns was found to benon-trivial. The existence and relative magnitude of these secondary arrivalshas been confirmed in measureddata. An additionalalgorithm has recently been developed to computethe exacttwo-way traveltimes associated with bottominterface reverberation by convolvingthe one-waytravel times from the sourceand the receiver. Presentedhere is a simultaneousvisualization of the one-waypulse propagation and the correspondingtwo-way reverberation. To determinethe influenceof the secondarymultipaths on reverberation,the bottomhas been altered in the nearfield to removethe multipathinfluence. This also shows the errors encountered inpredicting reverberation when only the incident field is computed. [Work supportedby ONR.] 8:55 4aUW3. Animationsof acousticalpulse (time-domain)signal propagationin a realisticwaveguide to high frequencies, NatslyA. Sidorovskaia(Dept. of Phys.,Univ. of NewOrleans, New Orleans, LA 70148)and Michael E Werby (NavalRes. Lab., Code7181, Stennis Space Center, MS 39529) Recentdevelopments have made it possibleto performpropagation calculations in realisticoceans to highfrequencies. It is possibleto dealwith on the order of hundredsof modesrather quickly and by storingthe frequency-domain field over some specified rangeover the watercolumn and for a fine frequencymesh, it is possibleby a new Fouriertransform algorithm to reconstruct time-domainsolutions in reasonabletimes. Time framescan be producedfor variouspulse forms and realisticanimations can be created.Thus this enables concentration on the physicsof pulsearrivals as well as distortioneffects from submergedinclusions. The insightthat arises from these calculations, whether they are still shots or actualanimations, is very revealing and affords an additional perspectiveof thecomplete process that otherwise would not be revealedby lessambitious calculations. A variety of animationsand still shotsfor severalphysical environments are presentedand much of the theoreticalresults with the intuitivepowers that only animationsoffer are described. [Work supported by NavalResearch Laboratory and Office of NavalResearch.] 9:20 4aUW4. Interfacewaves in seafloorpropagation and scatteringproblems. RalphA. Stephenand S. ThompsonBulmer (Woods Hole Oceanograph.Inst., 360 WoodsHole Rd.,Woods Hole, MA 02543) Interfacewaves often play a significantrole in seafloorpropagation and scattering problems. Because they are not solutions to the pureacoustic wave equations, but requirea nonzeroshear modulus, they are frequentlyoverlooked in modeland inversion studies. Thereare two areas in particularwhere interface waves are relevant in underwateracoustics: (1) whenthe source and receiver are close (in termsof wavelengths)to the seafloor,and (2} wheninterface roughness or heterogeneitiesnear the interfaceact as secondary scatterers.The first caseis importantfor low-frequencypropagation in shallowwater. The secondcase is importantin scattering problemssuch as low-angle,monostatic backscatter or the scatteredfield of seaflooror buriedordinance. Insight into the generation andpropagation mechanisms of interfacewaves can be gained through time-domain shapshots of thewavefield and by analysisof time seriesrecord sections. Animations of wavefrontpropagation in verticalslices through the seafloorshow clearly the energypartitioning betweenthe various body and interface wave types. [Work supported by ONR.] 9:45 4aUW5. Understanding acoustic propagation in shallow water via animations. ]ohn B. Schneider,Patrick ]. Flynn, and Shira L. Broschat (Schoolof Elec. Eng. and Comp.Sci., WashingtonState Univ., Pullman,WA 99164-2752) Modelingthe propagationof acousticenergy in shallowwater is difficultdue to the complexityof the environment.Roughness at the air-sea interfaceand bottom, inbomogeneities in the watercolumn and sediment,and discretescatterers affect the propagation. Althoughmany modelingtechniques are availableto studythis problem,arguably none is generalenough to providerobust and accurateresults over a largeregion when several complicating physical features are present.Instead, simplifying assumptions are often made,and the effectof suchassumptions on the model'svalidity is uncertain.Here, propagationin shallowwater is studiedvia animationsof tho rosultsobtalucd using thc finitc-differencetime-domain method (a powerful, but complltationallyexpensive, modelingtechnique with few inherentassumptions). Such animations provide insight into the relativeimportance of certainphysical featuresthat is not easilyobtained from "still" data.Two differenttypes of animationsare discussed.One employsa "side-by-side" comparisonin whichtime-domain propagation is shownin boththe presenceand absenceof a certainphysical feature. In the other, time is heldconstant and a physicalfeature is variedfrom frameto frame.Creation of animationsusing freely availablesoftware is alsodiscussed. [Work supportedby ONR.] 10:10-10:30 Break 2552 J. Acoust.Soc. Am., VoL99, No. 4, Pt. 2, April1996 131st Meeting:Acoustical Society of America 2552 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 10:30 reportson a recentexperiment which provides significantly more acoustic dataalong different propagation tracks and, consequently, permits high 4aUW6, Modeling target strength of reflectiveobjects using resolutionof physicalprocesses in range.A mode-filteringtechnique is computerray tracingtechnique, GerardP. Gay (Dept.of Mech.Eng., usedto construct•nodal structure from the data,while modalattenuation is Cooper Union, 51 Astor P]., New York, NY 10003) and Daniel R. obtainedfrom spectralratios. The evolution of modal structureis deter- Raichel (Acoust.Res. Ctr., CooperUnion, New York,NY 10003) minedas a functionof frequencyand range.This is examinedin view of Monostatictarget strengthof perfectlyreflective geometric objects environmentalparameters along a selectedpropagation track. Numerical- maybe predictedthrough the use of a non-recursiveray tracing technique. simulationsare carriedout usinginterpolations of the knowngeoacoustic This solutionis basedon the analyticalinfinite series solution of the wave enviromnentand employing the KRAKEN normalmode and RAM para- equation.The ray tracingtheory embodies the premisethat the properties bolicequation models. Results from these simulations are compared with of sound,with wavelengthssmall compared to the sizeof the targetob- the experimentaldata. jects,are analogous to thoseentailed in thepropagation of electromagnetic waves.Simple geometric objects including spheres, disks, and cylinders 11:15 aregenerated as object-oriented three-dimensional models; objects are ray 4aUW9. Mapping acousticechosounder data to human color vision. tracedso the model may be viewed and results may be calculated. The data FrankA. Boyle (Appl.Res. Labs., Univ. of Texas,RO. Box 8029,Austin, producedby the use of this techniqueagree with theoreticalresults, TX 78713-8029) therebysuggesting the validity of this method. A colormappingalgorithm was developedand appliedto echosounder 10:45 datafrotn the seafloor.The techniqueoffers a si•nplemethod of conveying subtleinformation about the seabedthat might be usefulin sedimentclas- 4aUW7. Modal time series structure in range and depth of a sification.Features with differentspectral content appear in a processed shallow-waterarea. David P, Knob]es (App]. Res. Labs., Univ. of imagewith differentshades of color.Broadband scatterers, such as rigid Texas,P.O. Box 8029, Austin, TX 78713-8029) objectsor interfaceroughness e•nerge as white or gray features,while narrow-bandscatterers, such as trappedgas bubblesappear with a hue A theoreticalanalysis of pressuretime seriesgenerated by smallex- correspondingto their resonancefrequency. The methodhas the potential plosivesources and recorded on bothan HLA anda VLA deployedin the to resolvethe mnbiguitybetween rigid and gassysedi•nents, which are Hudsoncanyon region off the New Jerseycoast near the AMCOR 6010 indistinguishablein a grayscaledisplay. A descriptionof thecolormapping boreholeis presented.The SVP in the watercolumn has an isovelocity algorithm,followed by a presentationof the resultsof its applicationto layerdown to a depthof about20 m followedby a strongnegative gradient echosounderdata and a discussionof theirinterpretation is given.[Work to about45 •n wherethe profile becomesapproxi•nately isovelocity to supportedby NRL.] theseafloorat 73 m. This sound-speedstructure creates a uniquetime series structureon the VLA as a functionof sourcerange. The data are simulated 11:30 with a broadbandnormal •node- approach recently discussed in the litera- ture[J. Acoust. Soc. Am. 98, 1682-1698(1995); IEEE J. Ocean.Eng. 21 4aUW10. Wave field visualization as an interpretational tool in (I) (1996)].The representation of the spatial and temporal structure of the borehole geophysics. V. N. Rama Rao, Henrik Schmidt, and Kim time seriesin termsof a •nodalstructure reveals several unique aspects of Vandiver (Rtn.5-007, MIT, Dept.of OceanEng., 77 MassachusettsAve., thestructure of the SVP in the watercolumn and the geoacoustic structure Cambridge,MA 02139) of thebottom. The detailsof the modalstructure of the soundfield clearly definethe propagation mechanisms in thewater column and the interaction A hybrid model for computingthe radiation from a boreholewhile with the seafloorand sub-botto•nsediment layers. [Work supportedby drillinghas been developed. A modelfor modalpropagation in a radially AdvancedResearch Projects Agency.] layeredborehole is coupledwith the OASES codefor full wave modeling of the resultantseismic wave field. The couplingis performedusing the conceptof effectivesources. First, an equivalentseismic source array that 11:00 producesthe samefar-field radiation as the boreholeis determined.This 4aUW8. Mode coupling and mode stripping in propagation across sourcearray is then introducedinto the layered earth model and the re- the range-dependentAtlantic GeneratingStation (AGS) site. Indra suitingseismic field is computed.Three propagatingmodes exist in the Jaya (RensselaerPolytechnic Inst., Troy, NY 12180), MohsenBadiey boreholein the presenceof the drill-pipe.The individualmodes radiate (Univ. of Delaware,Newark, DE 19716), and William L. Siegmann into the formationin a patternthat is dependenton geophysicalproperties, (RensselaerPolytechnic Inst., Troy, NY 12180) with the resultingradiation pattern being extremely complex and difficult to interpretphysically. Here, visualizationand animationin particularhas The complicatedpatterns of modalstructure and attenuationobserved provento be an extremelyuseful tool. For example,animation allows the in soundpropagation through a range-dependentshallow-water environ- direct identificationof the co•nplexarrival patternrecorded on surface ment are usedto investigateand visualizethe mechanismsof mode cou- mountedgeophones. The fundamentaldifferences between the radiation pling and stripping.Broadband experiments have been carried out at the patternsin fast and slow formationsare also clearly demonstratedusing geologicallyknown AGS site in the past few years. This presentation computervisualization and animation. 2553 J. Acoust.Soc, Am,, Vol. 99. No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society of America 2553 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, 16 MAY 1996 SALON E, 8:30 A.M. TO 12:00 NOON Meeting of Accredited Standards Committee S12 on Noise to be held jointly with the U.S. TechnicalAdvisory Group for ISO/TC 43/SC1 Noiseand ISO/TC 94/SC12Hearing Protection D. L. Johnson, Chair S12 EG&G Special Projects,Albuquerque Operations, Albuquerque, New Mexico 87119-9024 P. D. Schomer,Chair, U.S. TechnicalAdvisory Group (TAG) for ISO/TC 43/SC1, Noise U.S. CER,L,P.O. Box 4005, Champaign,Illinois 61820 H. E. yon Gierke,Vice Chair,U.S. TechnicalAdvisory Group (TAG) for ISO/TC 43/SC1,Noise 1325 Meadow Lane, YellowSprings, Ohio 45387 E. H. Berger,Chair, U.S. TechnicalAdvisory Group (TAG) for ISO/TC 94/SC12,Hearing Protection Cabot SafetyCorporation, 7911 ZionsvilleRoad, Indianapolis,Indiana 46268-1657 StandardsCommittee S12 on Noise.Working group chairs will reporton theirprogress for theproduction of noisestandards. The interactionwith ISO/TC 43/SC 1 and ISO/TC 94/SC 12 activitieswill also be discussed,with referenceto the internationalstandards underpreparation. A reportwill be givenon the meetingof ISO/TC 43/SC1in Pretoria,South Africa, held in February1996. The Chairsof therespective U.S. Technical Advisory Groups (H. E. yonGierke and E. H. Berger)will reporton current activities of these international Technical Subcommittees under ISO. Scopeof S12. Standards,specifications and terminology in the fieldof acousticalnoise pertaining to methodsof measurement, evaluation,and control;including biological safety, tolerance and comfort and physicalacoustics as relatedto environmentaland occupationalnoise. THURSDAY AFTERNOON, 16 MAY 1996 MT. RUSHMORE, 1:30 TO 4:45 P.M. Session4pAA ArchitecturalAcoustics and Noise: Current Topicsin HVAC Noise Bennett M. Brooks, Cochair BrooksAcoustics Corporation, 27 Hartford Turnpike,Vernon, Connecticut 06066 Timothy J. Foulkes,Cochair CavanaughTocci Associates, Inc., 327F BostonPost Road, Sudbury, Massachusetts 01776 Chair's Introduction--l:30 Invited Papers 1:40 4pAA1.New developmentsin noisecontrol for HVAC systems.Timothy J. Foulkes (CavanaughTocci Assoc., Inc., 327F Boston PostRd., Sudbury,MA 01776) TheHVAC equipment industry isnot known for rapid change. Although control systems have improved rapidly over the past few years,fans are still much the same as they were 20 yearsago. Accessories such as air diffusersand vibration isolators have gone throughsmall, incremental changes in thesame time period. In thepast 12 months, several new products have caught the author's attention.These represent significant improvements innoise control and/or design flexibility and installation quality. This presentation willinclude product information onthese new products along with a discussionoftheir pertinent advantages. Industry trends such as wideravailability of sounddata and custom engineered air handlingunits will alsohe discussed. 2554 d.Acoust. Soc. Am., Vol. 99, No. 4, Pt.2, April1996 131stMeeting: Acoustical Society of America 2554 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 4pAA2,Assessment ofHVAC sound power data for sensitive spaces. Kevin C. Miller and Martin J. Beam (Miller Henning Assoc.,Inc., 6731 WhittierAve., Ste. A110, McLean, VA 22101) Certificationtesting of airhandling unit sound power (PWL) indicates that individual unit PWL can vary significantly from manufacturerpubfished data. Published data are typically based on a limitednumber of actualtests with results extrapolated forother fansizes and operating conditions. Although published data are normally acceptable forroutine applications, indiscriminate usefor sensitivedesigns (studios, theaters, conference centers, etc.) can result in excessive finished space noise leveLq. The fact that the design goalshave been exceeded can be accuratelydocumented. The exact reason for theexceedonce, however, cannot be asfirmly establishedin a complexsystem. Certification PWL testing of air handlingunits prior to installationcan detect PWL variationsfrom thepublished data. Individual unit PWL certification was often not cost effective prior to the derelopement of sound intensity and the establishmentand use of recognizedstandards for in situPWL testing (e.g., ASA 104-1992,ANSI S. 12.12.1992). Case histories to be presenteddocument fan PWL variations from published data of up to 10dB andhigher in certainoctave bands. 2:30 4pAA3.Air pedestaldiffusion method of introducingair silentlyto spaces.Robert Essen and DamJan Doria /ArtecConsultants Inc., 114W. 26 St., Floor9, New York,NY 10001) In recentyears the drive to air conditionperformance halls with greater energy efficiency and comfort has brought supply air terminalscloser to the ears of audiencemembers. Introduction toNorth America of theEuropean approach of airvolume displacement hasrequired development of silent air terminals that coordinate with audience seating and allow greater efficiency and comfort. Artec ConsultantsInc. has worked with leading seating manufacturers to develop pedestal chair supports and other floor mounted devices thatfunction as terminals for air supplied from underfloor plena. The Ford Centre in North York Ontario incorporates onesuch design, aswill severaladditional facilities in NorthAmerica and Europe that are presently under construction. Completed facilities have met the designnoise levels. This paperwill examinethe recentdevelopment of theseterminal devices and discussthe benefitsand co•nplicationsassociated with their implementation. 2:55-3:10 Break 3:10 4pAA4.Duct breakout sound associated with ductsconstructed of fiberglassduct board. DouglasD. Reynoldsand Keith M. Degner(Ctr. for Mech. & Environ.Systems Technol., College of Eng.,Univ. of NevadaLos Vegas, Los Vegas, NV 89154-4040) Soundbreakout from rectangular HVAC ducts constructed of fiberglass duct board has been investigated. Duct sizes that were testedwere 12x 12, 12x24, 12x 36, 24x 36, and36x 36. All dimensionsare in inches.Four duct lengths for eachduct size were tested:4, 8, 12,and 16 ft. Thesound breakout values for thefiberglass duct board were compared to correspondingvalues obtained fromsimilar sized rectangular sheet metal ducts. Major objectives of the studywere to obtainduct transmission loss values for rectangularducts constructed of fiberglass duct board, to comparethese values with corresponding values obtained from similar sized rectangularsheet metal ducts, and to specifyconditions in whichrectangular ducts constructed of fiberglass duct board can be used in situationswhere the controlof ductbreakout noise is important. 3:35 4pAA5.The influenceof fanson low-frequencynoise and rumblein HVAC systems.Jerry G. Lilly (JGLAcoust., Inc., 6421 Lake WashingtonBlvd. N.E. #209, Kirkland, WA 98033) Low-frequencynoise and rumble problems can occur in HVAC systemsdue to problemswith the fan, the duct sytern, the fan/duct interface,and even the control system. This discussion deals with fan relatedproblems only. Items that will be discussedinclude: the importanceof fan-typeselection (centrifugal, axial, plenum, etc.), selecting the right fan size for therequired duty, the importance of aerodynamicconditions at thefan inletand outlet, and the problems associated with VAV controlmechanisms. The discussionwill also addressthe importance of propervibration isolation and how to preventcommon problems. Specific project examples will be included. ContributedPapers 4:00 seswill be conductedcan be developedand storedto minimizethe time associatedwith inputtingdata to the program.The programhas options for 4pAA6. Computer program for conductingacoustical analyses of printingout tabulatedresults and noisecriteria and room criterioncurves HVAC systems. DouglasD. Reynoldsand Scott C. Mitchell (Ctr. for for inclusionin reports. Mech.& Environ.Systems Technol., College of Eng.,Univ. of NevadaLas 4:15 Vegas,Las Vegas,NV 89154-4040) 4pAA7. Higher-order modal reflection and transmissionin acoustic An interactiveWindows-based computer program has been developed waveguidestep discontinuities. Ralph T Muehleisen (Appl.Res. Lab., that can be usedto conductcomplete acoustical analyses of HVAC sys- PennState Univ., P.O.Box 30, StateCollege, PA 16804) tems.The programcan be usedto tracksound from a HVAC soundsource suchas a fan to a roo•n. Both soundfrom a singlepath betweena sound Analytic expressionsfor the transmissionand reflectioncoefficients of sourceand roo•n or from multiple pathsbetween a soundsource and room higher-ordermodes at a step discontinuityin an acousticwaveguide are can be investigated.The programhas a full set of editing featuresthat developed.The equationstake on the fmniliar form of an impedancedis- include change,delete, and insert options which allow an individual to continuitywhen written in matrix form. Numericalresults show that there interactivelydesign an HVAC systemto meet specifiedacoustic design is significantmodal coupling which indicatesthat the couplingcannot be criteria.Design templates for systemsin which multipleacoustical analy- ignoredin the designof duct systems. 2555 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society of America 2555 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 Whenwritten in matrixform theequations take on thestandard form of an impedancediscontinutity. Numerical results for a rightangle bend and a T 4pAA8. Higher-ordermodal reflectionand transmissionin acoustic waveguidejunctions. RalphT. Muehleisen(Appl. Res. Lab., Penn State junctionshow that thereis significantcoupling between modes, especially Univ., P.O.Box 30, StateCollege, PA 16804) to the plane-wavemode. The resultsindicate that modalcoupling cannot be ignoredin thedesign of activeand passive attenuators that need to work Analyticexpressions for thetransmission and reflection coefficients of higher-ordermodes in acousticwaveguides are developedand explored. at higherfrequencies. THURSDAY AFTERNOON, 16 MAY 1996 CANYON HALL, 1:30 TO 5:20 P.M. Session4pAB Animal Bioacoustics:Intra-Specific Variations in Animal VocalizationsII Robert H. Benson, Chair Centerfor Bioacoustics,MS 3367, TexasA&M University,College Station, Texas 77843-3367 Chair's Introductinn--l:30 ContributedPapers 1:35 were proportionatelymore like EasternAustralia. Kaikoura song was more similar to EasternAustralian song than Tongansong. These regional dif- 4pABI. Quantitativeanalysis of corvid (classaves) vocalizations as a ferencescan be consideredto be dialectsthat are maintainedthrough possibletaxonomic tool. Mary K. Coldten (Ctr. for Bioacoustics,Texas culturaltransmission of regionalvariants. The resultssuggest some migra- A&M Univ., CollegeStation, TX 77843-3367) tory exchangeamong widely separatewintering regions of area V and Vocalizationsof scrubjays (Aphelocoma coerulescens texana and A.c. speculationthat songsharing occurs ihroughout migration and breeding woodhouseii)and gray-breastedjays (A. ultramarinaconchit) were re- seasons. cordedat eight sitesin Texas.All three taxa were consideredallopatric. While many call types were not consistentin structureand tendedto 2:05 intergrade,two structurallydistinct call typeswere identified as sharedby all taxa at all sites.Differences in acousticstructure of bothcall typeswas 4pAB3. A nonparametric statistical approach to representation of greatestbetween species. Acoustic structure between subspecies was less variations within a class of marine mammal vocalizations. Thomas distinct,with uniqueacoustic structures occasionally being sharedwith the J. Hayward (U.S. Naval Res. Lab., Washington,DC 20375-5350) nearestpopulation of anothersubspecies. Morphometric analysis revealed a similar pattern,with the mostdifferentiation at the specificlevel, fol- A nonparametricstatistical approach has been developed for represent- lowed by subspecificand, lastly, by populationaldifferentiation. Of par- ing variationwithin a classof vocalizations.This statisticalrepresenlalion ticularinterest was a small,isolated population ofA. coerulesce,sfound in permitscomputationally efficient a postertortestimation, based on training the Texaspanhandle. Although breeding populations may haveexisted for in a supervisedlearning context, of the probabilitydensity associated with only two or three decades,morphometric analysis of both call types the class.This approachavoids the assumptionof parametricforms for the showedmarked vocal differentiation from other Texas scrub jays. Analysis probabilitydensity; parametric forms may not be suitablein caseswhere of one call type suggestedseparation from the otherpopulations of scrub the probabilitydensity has a complex,multimodal character. Two applica- jays at thesubspecific level, while theother call typesuggested separation tionsof the statisticalrepresentation are described.First, the a postertort at the specificlevel. densitiesassociated with severalclasses of transientscan be computation- ally "evaluated"on a new sampleto providea basisfor classificationof marine mammal vocalizations as well as a measure of confidence in that 1:50 classification[i. Acoust.Soc. Am. 96, 3312 (1994); 98, 2969 (1995)]. Second,the statisticalrepresentation provides for quantitativecharacter- 4pAB2. Dialects in South Pacific humpback whale song. D.A. Helweg (Dept. of Psych.,Univ. of Auckland,Private Bag 92019, izationof variabilityusing information-theoretic measures. Examples of Auckland, New Zealand), D. H. Cato (2DSTO, Pyrmont. NSW, bothapplications are presented. [Work supported by ONR andNRL.] Australia),P. F. Jenkins (Univ. of Auckland,Auckland New Zealand),and C. Gardgue (OR STOM,Noumea, New Caledonia) 2:20 Humpback whales (Megaptera novaeanghae) migrate annually be- 4pAB4. Interindlvidual variation in the songsof humpback whales. tween high-latitudesummer feeding waters and low-latitudewinter mating Adam S. Frankel (BioacoustiesRes. Program, Cornell Univ., 159 waterswith a high degreeof site fidelity. During migrationand in winter SapsuckerWoods Rd., Ithaca,NY 14850) waters,adult (male) humpbacksproduce long complexsongs. Song con- tent is dynamic,but singersincorporate changes as they occur.Song shar- The functionof humpbackwhale songremains elusive. Humpbacks ing acrossregions is cultural,thus similarityof songsfrom differentre- primarilysing on the winteringgrounds. Many hypothesessuggest a male gionsmay be an index of reproductiveisolation. Songs recorded in Tonga, advertisementfunction. It hasbeen suggested that all whalesof a popula- New Caledonia, Eastern Australia, and Kaikoura, New Zealand, in the tionsing the same version of song,and ils structureslowly evolves during winter of 1994 are compared.The songfrom Kaikourais the mostsouth- andbetween singing seasons. Field observationsof 1989 songindicated erly recordingof song,over 2000 km southof winter migrationtermJul. subgtantialvariation in the songof humpbacks.The questionremained, Seventhemes were shared by all regionsplus two themesnot observedin were the differencesbetween individuals greater than thosebetween suc- Tongs.Differences in regionalvariants were mostpronounced between cessivesongs of an individual.The songsof 11 whaleswere sampled Tonganand Eastern Australian song. New Caledonian and Kaikouran song duringan 8 dayperiod, to reducethe probability that song evolution would 2556 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of Amedca 2556 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 affectthe results. Six unitsfrom three themes were sampled from four vailingbelief, it has beenfound that importedfire antscan use acoustic songsfrom each whale. Unit duration, lowest frequency, bandwidth, fre- signalsfor meaningfulcommunication. Signals have been recorded in situ- quencyof peakamplitude, and source level were measured. A repeated ationssuch as alarm, distress, and attacking prey and also what appears to measuresANOVA foundsignificant differences between individual whales be an all's-wellsignal. These were analyzed and distinct time-modulation andno suchdifferences were found between successive songs of thesame differenceswere found depending onthe situation. Acoustic signals appear individual. These data indicate that there are real measurabledifferences to be usedfor urgentcommunication. Ant responseprovides an indication betweenthe songsof differentindividual whales. These individual differ- of thesignificance of thesignals. The frequency range is principallybelow encescould be usedas a basisfor femalechoice of males,based on song about2 kHz.The sound-pressure level of a generalalarm signal was found features.While this remains untested, these data are necessary for sucha to be approximately40 dB (A), which is aboutthree times the level of a hypothesis. faint whisper.Background noise inside an ant moundis low and interior tunnelscan act as waveguides. 2:35 3:20-3:35 Break 4pAB5. Interspecific versus intraspecific variation in alarm call vocalizationamong two speciesof capuchinmonkey. KimberlyS. Norrisand Jeffery C. Norris (MarineAcoust. Lab., Ctr. for Bioacoustics, TexasA&M Univ., 5007 Ave. U, Galveston,TX 77551) Inter-and intraspecific variation in alarmcalls were compared for two 3:35 speciesof free-rangingcapuchin monkey: the wedge-cappedcapuchin (Cebusolivaceus) and the white-facedcapuchin (Cebus capuchinus). 4pAB8, lntraspecific variations in finback (B. physalus) 20-Hz Alarmcalls in eachcase were made in the presenceof the samepredator, doublets:An acousticmultipath interpretation. V. Premusand J. L. a boa constrictor.Vocalizations (n=40) were comparedfor commonly Spiesberger(Dept. of Meteorol.and Appl. Res.Lab., PennState Univ., examinedacoustic parameters (e.g., signal duration, frequency, and ampli- University Park, PA 16802) tude variables), as well as for vocal featuresfound to be acousticcues to themonkeys [e.g., bandwidth of dominantformant; change in frequencyof Biologistshave pointed to differencesin receivedcalls as evidencefor thedominant formant (see Norris, 4aAB3)]. Additionally, correlations of someseparation in finbackpopulations in differentlocations [Watkins spectrogramswere performedusing CANARY. Interspecificvariability et al., J.Acoust. Soc. Am. 82, 1901-1912(1987)]. More specifically, it has wasfound to besignificantly greater than intraspecific variability for signal beenconcluded by Thompsonet al. thatthe uniquefinback doublet inter- duration (F=45.30;p<0.0001), maximum frequency (F=8.52; pulseintervals recorded in theGulf of Californiaconstitute corroborating p<0.0059), and formantnumber (F= 10.32;p<0.0027). However,inter- evidencefor the hypothesisthat "Gulf of Californiafin whalesmay be a specificvariability of calls was not significantfor any of the acoustic separatepopulation, distinct from fin whalesin nearbyPacific regions" parametersfound to be usedas perceptualcues for the two species.The [Thompsonet al., J. Acoust.Soc. Am. 92, 3051-3057(1992)]. An alter- evolutionaryand ecologicalsignificance of these findingswill be dis- nativeexplanation is offered--thatregional differences in finbackdoublet cussed. interpulseintervals may be accountedfor by differencesin acousticpropa- gationconditions. In this work, a broadbandacoustic propagation code is 2:50 combinedwith an empiricallyderived geoacoustic seafloor model for the purposeof interpretingfinback doublet sequences recorded in the northern 4pAB6. Spectrogramcontour features for intraspecificclassification Gulf of Californiaby Thompsonet al. in 1987[ibid.]. The resultis thatfor of narrow-bandanimal sounds. Ben Pinkowski (Dept.of Comput. rangesless than 30 km, it is possibleto explainthe appearanceof the Sci., WesternMichigan Univ., Kalamazoo,MI 49008) finbackdoublet in termsof multipathpropagation through the water col- Recent research has indicated that contour features obtained from com- umn and the seafloor.Further, the interpulsedelay is demonstratedto be stronglyrange dependent.Scientists might considerthe possibilitythat puterimaging are usefulfor characterizingsome interspecific differences in narrow-bandanimal sounds lB. Pinkowski,J. Acoust.Soc. Am. 95, finbacksmake use of multipathintervals to estimatedistances to other 3419-3423 (1994)].Contour features may also characterize the intraspe- finbacks,perhaps for reasonsrelated to socialbehavior. cific differencesof animalsounds that vary amongindividuals. To examine this possibility,six songsfrom eachof ten easternbluebirds (Siolia sialis) (5 malesand 5 females)recorded during 1991and 1992in southwestern Michiganwere digitizedat 22 kHz, convertedto spectrogramimages, and 3:50 analyzedfor contourusing Fourier descriptors (FD's). Followingsmooth- ing, thresholding,and segmentation,the spectrogramcomponents corre- 4pAB9. Removal of multipath effects from marine mammal spondingto threeor more basicnotes were mergedby a simplepixel vocallzations. Aaron M. Thode, Gerald L. D'Spain, William S. aggregationalgorithm to yield a single contourper song.The contour Hodgkiss,and W. A. Kuperman (ScrippsInst. of Oceanogr.,Univ. of borderwas then used to computea 512-pointDFT. With 16 low-orderFD's Californiaat San Diego, La Jolla, CA 92093-0205) per song,58 of the 60 songs(96.7%) werecorrectly classified by a linear discriminantfunction. Male songswere more varied and complex and Long-duration(>1 s) marinemammal vocalizations (i.e., blue whale hencemore difficult to classifyby contouralone than were femalesongs. [Worksupported by NIH.] calls) generateechos and other multipatheffects [McDonald et al., J. Acoust.Soc. Am. 98, 712-721 (1995)],obscuring the original structure of the call, which may contain valuable anatomicalinformation about the 3:05 animal. Severaldeconvolution techniques are evaluatedfor their effective- ness in removing multipath effects from both a hypotheticaland actual 4pAB7. Acoustic communication by imported fire ants. Robert marinemammal call. The evaluationis first performedon a modelof a Hickling,Wei Wei (Natl. Ctr. for PhysicalAcoust., Univ. of Mississippi, whalecall in an isovelocitywaveguide with noise,where the sourcesignal University,MS 38677),and Layone Lambert (ARS DeltaStates Res. Ctr., is known and can be comparedwith the output of the deconvolution gtoneville, Mg 38776) schemes.The methodsare then apphed to two blue whale calls recorded Although it is well known that ants generatesound by stridulation duringan experiment (SWellEx-3) in July,1994 in 200-mwater. The depth usinggaster-flagging motion of the abdomen,acoustic communication by andrange of the animalat thosetwo times hadpreviously been determined antsis generallybelieved to be almostnonexistent compared to chemical by matchedfield processing.As the positionof the animal is known, the communicationusing pheromones [Holldabler and Wilson, The Ants (Har- resultingmultipath propagation can be computedand the accuracyof the vardU. R, Cambridge,MA, 1990),pp. 255-259]. Contraryto thispre- techniquesin identifyingthose multipaths determined. 2557 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society of America 2557 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 4:05 ingsof thesounds and with videorecordings of theenvironments in which the soundswere producedin order to assistin identifyingsources and 4pAR10. An acousticperception model for echolocationsignals. effectsof the sounds.Modular signalprocessing soft'ware, integrated with MathewJ. Palakal,Uday Murthy (Dept.of Cornput.Sci. IUPUI, 723 W. a highlevel programming language and operated on graphicsworkstations MichiganSt., SL 280, Indianapolis,IN 46202), and Donald Wong enablethe researcherto selectspecific types of soundswhich are foundto (IndianaUniv., Indianapolis, IN 46202) occurin typicalenvironments of selectedanimals. The systemcan also be Bats that echolocateusing biosonar pulses perceive their targetas an usedto synthesizecalibrated sets of similarsounds to be usedas inputs for auditoryimage by extractingacoustic cues conveyed in thetarget-reflected controlledexperiments investigating the effectsof the soundson animals. echoes.Neurophysiological studies suggest that a largemajority of cortical In this paper,a typicalworkstation-based system for performingtime- neuronsfound in FM batsare delay sensitive.Moreover, these neurons are frequencyanalysis of digitallyrecorded sound will be described.Operation tonotopicallyorganized and have a bestdelay (BD) at whichthey respond of the systemwill be illustratedwith resultsfrom analysesof sounds maximallyto an inputstimulus. In orderto understandthe role of these collectedduring a recentsurvey of the acousticenvironments of captive neuronsduring pulse echo processing, a mathematical model capturing the and wild fish and with specialtysounds synthesized for currentinvestiga- functionalityof delaysensitive neurons (DSN) hasbeen developed. As a tions of effects of noise on fish. firstapproximation, response to a pulse-echopair of a DSN is derivedas, y(t)=exp[ i*(fi-•)•/2'o'•], wherefi is bestdelay of theneuron, • is 4:50 arrival time of the echo, i is neural spikes,and •r is delay range of the 4pABI3. An "acoustic-signature"model of vowel evolution. Michael neuron.A two-dimensionalcortical response map (CORMAP) of DSNsis J. Owren (Dept. of Psych.,Reed College,3203 SE WoodstockBlvd., then developedbased upon the bestfrequencies and the abovestated re- Portland,OR 97202) sponseproperty with varyingBDs. The CORMAPis thensimulated using phantomtargets containing multiple echoes. Once a pulseis sentand as the Recentwork in bioacousticshas emphasized the importanceof cuesto echoesbegin to arrive for every 8k, the CORMAP generatesa response individual-and kinship-identityin "signature"calls producedby many map as the DSNs fire. The firing patterosoccur at various8k can be animalspecies, including nonhuman primates. Applying the source-filter analyzedto estimatetarget distance and structural information. [Work sup- approachto soundproduction in monkeysand apes,it is proposedthat portedby NSF.] low-pitched,tonal calls may be significantlybetter-suited to providing theseindexteal cues than are noisyor high-pitchedvoealizations. As the 4:20 supralaryngealvocal tract is relativelyinflexible in many primates,har- monically rich calls produced by different individuals should exhibit 4pABll. Experiments on the directional starfie reflex in goldfish. stable,subtly distinctive spectral characteristics due to intraspeciesvaria- ThomasN. Lewis, TheresaJ. Woods,and PeterH. Rogers (GeorgeW. tion in vocal tractsize, shape,and tissueproperties. Based on field studies WoodruffSchool of Mech. Eng., GeorgiaInst. of Technol.,Atlanta, GA of callsfrom baboons and rhesus monkeys, it is suggestedthat protohomi- 30332-0405) aids routinelyuttered vowel-like soundslong beforethe developmentof speech.Laboratory tests of pure-toneand formantfrequency discrimina- The acousticstartle reflex in goldfish(Carassius auratus) was studied tion in monkeysand humansfurther indicates that detailed formant-related experimentallyin the largeacoustic tank at GeorgiaTech. Individual free characteristicsin thesesounds were likely bothfunctionally important and swimmingfish were placedin an acousticallytransparent cage and posi- perceptuallysalient. Due to changesin facial morphology(probably re- tioned in the center of the tank. Their behavior was graded for a response fleetingdietary factors), shortening of theprotobominid vocal tract created to acousticsignals and the directionof responsewith respectto the sound selectionpressure for lower laryngeal position to maintain acoustic- source.A preliminarystudy indicatedtwo interestingfeatures. First, the signaturecues. Laryngeal descent therefore set the stagefor development fish was muchmore likely to respondin the "conect"direction (away of flexible vocal tract positioning,but was not itself an adaptationfor from the source)when responding to subthresholdstimuli. Second, there speech. was strongdependence of signalamplitude at Ihresholdon fish size. For the two weightgroups tested (1.6 g, n=3 and 23.6 g, n=4), the sound- 5:05 pressurelevel at thresholdwas 15 dB lower for the smallersubjects. The initialstudy has recently been augmented with testson a rangeof subjects 4pAB14. Variation in whistle-typeand rate produced by captive weighingbetween these two extremes.Also, sinceonly the firsthalf-cycle dolphins relative to in-water interactions with humans. T.G. of the acousticstimulus is thoughtnecessary to elicit the response,the Frohoff (DolphinData Base,321 High SchoolRd. NE, Brainbridge conceptof frequencyto characterizethe soundstimulus is inappropriate. Island,WA 98110),J. M. Packard,and R. H. Benson (TexasA&M Univ., Therefore,thresholds were measuredas a functionof signalrise time. A CollegeStation, TX 77843-2258) parallel effort has involved modelinga biologicallyrelevant stimulus: the acousticfield generatedby an attackingpredator. [Work supportedby The relativeimportance of expressionand symbolic content in acoustic ONR.] communicationof cetaceanshas been debated.These topicsmay be ex- andnedby observinghow generalrates of vocalizationschange with ex- citatorystate and how specificvocalizations vary independentlyof state 4:35 and dependupon content. In this study,whistles (0.32 to 22 kHz) of two captivebottlenose dolphins (Tursiops truncatus) were recordedunderwater 4pAB12. Time-frequency analysisof potentially disturbing soundsin the environments of captive and wild fish. Joseph A. Clark before,during, and after six swim sessionsin which the behaviorof the (CDNSWC, Code 734, Bethesda,MD 20084 and COMB, Ste. 236 dolphinsand four humanswimmers was controlledby a traineron the ColumbusCtr., 701 E. Pratt St., Baltimore,MD 21202), JaneA. Young dock.Sono•rams of 205 min of recordedwhistles were analyzed. Variation (CDNSWC, Bethesda,MD 20084 and COMB, Baltimore,MD 21202), of whistle-typeand rate was observedrelative to the threecontexts. The Amrit N. Bart, and YonathanZohar (COMB, Baltimore,MD 21202) contoursof distinguishablewhistles (n= 591) revealed32 types.Ten types were observedduring one contextonly; duringthe swim sessions.Almost Time-frequencyanalysis provides a detailedmeans to characterizefea- half of thewhistle types (15 to 32) weremore likely to occurprior to swim turesof soundswhich aright affect animals.Graphic displays of the ana- sessionsand the otherswere morelikely duringswim sessions.None were lyzed soundfields often reveal qualitativepatems and quantitativemea- morefrequent after swims. Rate of whistleswas significantly higher than suresthat can be usedas a basisfor comparingdifferent sound fields. The expectedduring the swim sessions (z=7.21) andlower than expected after displayscan be animatedand presentedin conjunctionwith audiorecord- the swim sessions(z = -0.03). 2558 J. Acoust.Soc. Am., Vol.99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2558 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 THURSDAYAFTERNOON, 16 MAY 1996 REGENCYA, 2:30TO 5:15P.M. Session4pPA PhysicalAcoustics: Thermoacoustics and Bubbles SameerI. Madanshetty,Chair Departmentof Mechanicaland Aerospace Engineering, Boston University, 110 CummingtonStreet, Boston, Massachusetts 02215 ContributedPapers 2:30 the thermalpenetration depth allowing the effects of partialthermal con- tactwithin the elements to beevaluated. These resulls will becompared to 4pPA1. Measurements with wire mesh stacks in thermoacoustic attemptsto buildtheoretical models of the heatexchange process. prime movers. ThomasI. Hoflerand Mark S. Reed (Dept.of Phys., Naval Postgrad.School, Monterey, CA 93943) Measurements with various wire mesh "stacks" in two different ther- moacousticprime movers are presented.Stirling engine regenerators are 3:15 commonlyconstructed by stackingdisks cut from wire mesh (i.e., wire clothor wire screen)in a tube.In additionto simplicity,this hastwo 4pPA4. Optimization of the performance of thermoacoustic advantagesfor primemovers. First, the wire is relativelyimpervious to refrigerators applying the short stack boundary layer moderatelyhigh temperaturesand second,the effectivetherma] conduc- approximation.M. Wetzeland C. Herman (Dept.of Mech.Eng., Johns tivity of the structureis one to two ordersof magnitudelower than a HopkinsUniv., Baltimore,MD 21218-2686) comparablemetal "parallel plate" structure.Since no linear theoretical thermoacousticmodels exist for thesewire meshstacks, this approachis A systematicapproach to optimizethe performanceof thermoacoustic simplyto measurethe performanceof severaldifferent mesh stacks. Initial refrigeratorsby usingthe COP (coefficiemof performance)is presented. resultsindicate reasonably good onset temperature and amplitudeperfor- For this purposefour main modulesof the thermoacousticrefrigerator mance.[Work supportedby Officeof Naval Research.] wereidentified: (i) the thermoacousticcore, (ii) theresonance tube, (iii) the acousticdriver, and (iv) the heatexchangers. The mainobjective of the analysiswas the optimizationof the thermoacousticcore, which consists of 2:45 the stack region of a thermoacousticrefrigerator, by applyingthe short stackboundary layer approximation. For theenthalpy and work flux equa- 4pPA2. Measurements of transient effects in thermoacoustics. tionsof the shortstack boundary layer approximation, which are the base Albert B. Jones, Jr. (Dept. of Psych., NortheasternUniv., 1600 for the calculationsof the thermoacousticcore's COP, 20 independent MassachusettsAve., Boston, MA 02115),Anthony A. Atchley,David D. designparameters were identified,and summarizedin a multidimensional Hebert,Hsiao-Tseng Lin, Ching-KaiMeng, and Arthur R. Salindong parameterspace. Introducing a normalizedmultidimensional parameter (NavalPostgrad. School, Monterey, CA 93943) spacethe numberof designparameters was reduced to ten. Settinglimits Most theoriesof thermoacousticphenomena deal with steady-state on the normalizeddesign parameters allowed us to identifythe threemost quantities.However, recent work by Prosperettiand co-workers is capable significantdesign parameters: (i) normalizedstack length, (ii) normalized of treatingthe transientpart as well. Motivatedby thesepredictions, mea- stackcenter position, and (iii) normalizedtemperature difference. Theo- surementsare presentedof the evolutionof the temperaturedistribution reticalcalculations of the thermoacousticcore's COP indicatecompetitive alonga stackplate exposed to a largeamplitude standing wave and the valueswith commerciallyavailable refrigeration techniques. [Work sup- evolutionof the pressurewaveform within a prime mover. Qualitative portedby the Officeof Naval Research;Martin Wetzelis alsosupported by measurementsof the former and both qualitative and quantitative measure- a scholarshipfrom DAAD.] mentsof the latterhave beenreported by variousauthors previously. The purposeof the presentseries of measurementsis to providea morecom- 3:30-3:45 Break pleteset of datato testtheoretical predictions. [Work supported by the Office of Naval Research.] 3:00 3:45 4pPA3. The heat transfer coefficient between stack and beat 4pPA5. Understanding the periodic driving pressure in the exchanger as a function of thermal penetration depth. James R. Rayleigh-Plessetequation. William C. Moss (LawrenceLivermore Brewster,Richard Raspet,and Henry E. Bass (Natl. Ctr. for Phys. Natl. Lab., L-200, 7000 East Ave., P.O. Box 808, Livermore,CA 94550) Acoust.,Univ. of Mississippi,University, MS 38677) The radialmotion of a singlebubble in a periodicallydriven liquid is The heat transfer coefficient between two elements of a thermoacoustic simulatedby solvingthe Rayleigh-Plessetequation and the fully com- deviceis definedas beingthe ratio betweenthe rate of heat flow between pressiblehydrodynamic equations. The hydrodynamicequations require a them and the temperaturedifference occurring at the interface.Previous muchsmaller far-field periodic driving pressure than the Rayleigh-Plesset experimentshave demonstratedthat this quantityis proportionalto the equationsto producethe samemaximum bubble radius. The discrepancyis amplitudeof acousticoscillation. For stackand heatexchanger duct widths resolvedby constructinganalytic traveling and standingwave solutions that are comparableto the thermal penetrationdepth, the heat transfer that show the relationshipbetween the far-fieldperiodic driving pressure coefficientwas foundto be equalto that predictedby a theorybased on the and the pressurenear the bubble, which is actually responsiblefor the elementsof the engine being perfect heat exchangers.Results of experi- radialmotion. [This work was performedunder the auspicesof the U.S. mental measurements of the variation of heat transfer coefficient as a Departmentof Energyby LawrenceLivermore National Laboratoryunder functionof frequencywill be presented.Increasing the frequencyreduces ContractNo. W-7405-Eng-48.] 2559 J. Acoust. Soc. Am., Vol. 99, No. 4, Pt. 2, April 1996 131st Meeting: AcousticalSociety of America 2559 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 lationfrequency was adjusted for the electricfield to excitethe monopole resonance,a transientacoustic signature was detectedby an electrically 4pPA6. An analytical and numerical study of nonlinear bubble shielded hydrophone in the surrounding oil bath. One mechanism for oscillationsin viscoelasticfluids. JohnS. Allen (Dept. of Mech. Eng., monopoleexcitation is that the energyof the bubble is increasedby the Univ. of Washington,Seattle, WA 98195) and RonaldA. Roy (Univ. of electricfield givinga positiveelectric pressure contribution proportional to Washington,Seattle, WA 98195) the squareof the field [P. L. Marstonand R. E. Apfel, Phys.Lett. 60A, The acousticallyforced oscillations of gas bubblesin Newtonianfluids 225-226 (1977)].The sameresult follows from a surfaceaverage of the havebeen studied extensively; however, these oscillations have not beenas Maxwell stressusing the Minkowski form of the stresstensor. Additional thoroughlyinvestigated in non-Newtonianfluids. An understandingof the monopolecoupling mechanisms may includea Helmholtz dielectricstress non-Newtonianeffects of viscoelasticityon this phenomenais particularly contribution(mitigated by theelectrostrictive liquid response) and vertical importantto medical acousticapplications involving oscillatorybubble oscillationsof thebubble's centroid in thehydrostatic pressure field. [Work behaviorin biologicaltissues and fluids.The stresstensor formalisms for supportedby the Office of Naval Research.] non-Newtonianfluids used in previousworks are reviewed and scrutinized. Inconsistenciesin the literatureand subsequentquestions about the traceof 4:45 the stresstensor are highlighted.As an initial step, a weakly nonlinear 4pPA9. The shape stability and interaction of millimeter-sizegas perturbationmethod is usedto examineforced single bubble oscillations in bubbles trapped in an ultrasonic standing wave. EugeneH. Trinh a viscoelasticfluid. A novelanalytical formulation is employedto makethe (JPL/Caltech,MS 183-401,4800 OakGrove Dr., Pasadena,CA 91109) perturbationapproach (method of multiplescales) to the problemmore tractable.Furthermore, this new formulationalso allows for complemen- A three-dimensionalstanding wave in a resonantliquid-filled cavity tar3 ' numericalsolutions. The physicallimitations and relevanceof this allowsthe trapping of multiplemillimeter-size air bubbles. The coupling of work with respectto medicalapplications are alsodiscussed. [Work sup- the radiationpressure stresses to the bubbleinterfaces induces a net down- portby NIH throughGrant No. RO1 CA39374.] wardforce counteracting gravity, a steady-stateshape deformation, and it alsodrives natural shape oscillations of largeamplitude under certain cir- 4:15 cumstances.The parameterspace for theshape stability of trappedbubbles in ultrasonicfields havinga frequencybetween 45 and 65 kHz has been 4pPA7. Intensified cavitation produced with pressure release and experimentallydetermined in puredistilled water as well as in aqueous rigid ellipsoidal reflectors. Michael R. Bailey and David T. solutionscontaining suffactants. The variable parametersare the sound Blackstock (Appl. Res. Labs.,Univ. of Texas,Austin, TX 78713-8029 pressure,the soundwavelength, and the bubble equilibriumradius. The and Mech. Eng. Dept., Univ. of Texas,Austin, TX 78712-1063) effectsof the soundfield intensityon the interactionof contactingand noncontactingneighboring bubbles are also experimentally investigated. In An underwaterbubble is well knownto grow in responseto a strong particular,a preliminarystudy of the impactof the soundintensity on the negativeacoustic pulse and then collapse because of inertialforces. Here coalescenceefficiency of contactingbubbles is conductedin purewater it is shownthat addingan auxiliarypositive pulse after collapsebegins andin aqueoussurfactant solutions. [Work funded by NASA.] intensifiesthe collapse. The negative-then-positivepulse sequence is pro- ducedby two ellipsoidalreflectors, each with an electricalspark at its near 5:00 focusf• andbeamed so thatthey share a commonsecond focus f2. The negativepulse is producedby a polyurethane(pressure release) ellipsoid, 4pPAI0. Collinear ultrasonicfour-wave mixing in suspensionsof thepositive by a brass(rigid) ellipsoid. A timingcircuit controls the delay particles and bubbles. ChristopherS. Kwiatkowskiand Philip L. betweenthe pulses.Cavitation is recordedby pitting(caused by bubble Marston (Dept. of Phys., WashingtonState Univ., Pullman,WA collapse)of an aluminumfoil membrane,which is centeredat f2 andlies 99164-2814) coplanar with the two crossedbeams. When the brass reflector is fired alone,a narrowpath of -- l-mm diameterpits appears.Firing the polyure- The interactionof soundwith soundin a suspensioncan be mediated thanereflector alone yields more widespread,-0. l-ram diameterpits. by thesuspension's response to acousticradiation pressure [H.J. Simpson When both are fired, a pitted X patternshows the positionof the two andI•L. Marston,J. Acoust.Soc. Am. 98, 1731-1741 (1995)]. Fourwave beams.If the delay betweenthe two firingsis 2-6/•s, the intersectionof mixingmediated by a suspensionwith collinearpump and probe waves is andthe centerlinebetween the pathserupts with deeppits. [Work sup- investigated.Radiation pressure from counterpropagating pump beams portedby ONR.] inducesa periodicgrating in the numberdensity of hollowglass micro- spheressuspended in a water/sugarmixture designed to makethe particles neutrallybuoyant. The Braggscattering amplitude was measured using a 4:30 singlePVDF transduceras both the probe soumeand receiverthat is 4pPA8, Acousticradiation from the monopoleresonance of a bubble parallelwith the standingpump wave nodalplanes. Reflection coefficients excited in a dielectrophoreticlevitator by oscillating electric fields. are calculatedby comparingthe reflectedand transmitted waves. By in- Philip L. Marston,Nathaniel K. Hicks, and David B. Thiessen (Phys. creasingthe particleconcentration, total Braggreflectivities from the es- Dept., WashingtonState Univ., Pullman,WA 99164-2814) tablishedgrating reaching 20% have been seen, which is stillin theregion of agreementbetween the Born approximation and transfer matrix theory. Dielectrophoreticlevitation of bubblesin an insulatingliquid appears The dynamicsof both the gratingformation and dissolutionhave been to be a novel way of studyingacoustic radiation from transientbubble studied,leading to theconclusion that grating dissolution is notdominated volumepulsations. Single bubbles were trapped in a spatiallyvarying dc bydiffusion alone. Bragg scattering by gratingsof gasbubbles caused by electricfield designed to givestable levitation. A few cyclesof a weaker cavitationwas detected.[Work supportedby the Office of Naval Re- oscillatingfield weresuperposed on the levitationfield. When the modu- search.] 2560 J.Acoust. Soc. Am., Vol. 99, No.4, Pt.2, April1996 131stMeeting: Acoustical Society of America 2560 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, 16 MAY 1996 MT. RAINER AND MT. MCKINLEY, 1:00 TO 5:00 P.M. Session4pPP Psychologicaland Physiological Acoustics: Auditory Capabilities and Proclivities of Normaland Impaired Listeners (Poster Session) Sid P. Bacon, Chair Departmentof Speechand Hearing Science, Arizona State University, P.O. Box 871908, Tempe, Arizona 85287-1908 ContributedPapers All posterswill be on displayfrom l:00 to 5:00p.m. To allowcontributors an opportunityto seeother posters, contributors of odd-numberedpapers will beat theirposters from I:00 to 3:00p.m. and contributors of even-numbered papers will beat their posters from 3:00 to 5:00 p.m. 4pPP1. Acousticreflex decay for modulatedsignals. RaymondD. Thusthe improvementin acousticreflex thresholdswith the increasein the Cook, Michael O. Ferguson,Joseph W. Hall III, John H. Grose, and repetition rate can occur as a function of the rate itself, even if a constant HaroldC. Pillsbury (Div. of Otolaryngol.,Head and Neck Surgery, Univ. numberof clicksare presentedat eachrate. of NorthCarolina, 610 Burnett-Womack,CB# 7070 ChapelHill, NC 27599) Temporaldecay of the acousticreflex provides the basisfor an objec- 4pPP3. Effect of probe frequency on the click-rate-induced tive audiologicaltest that differentiatescochlear from retrocochlearpa- facilitation of the acoustic reflex thresholds. Vishakha W. Rawool thologies.The classicsign of a neurallesion is a rapiddecay of the reflex (Commun.Disord. & SpecialEducation, Bloomsburg Univ., Bloomsburg, underconditions of pure-tonestimulation for frequencies1000 Hz and PA 17815) below.This restrictionto lower frequenciesis due to the fact that even Ipsilateralclick thresholdsobtained with a 226-Hz probe tone can normalears showdecay for higher-frequencysignals. At present,it is improveby approximately21 dB, with an increasein the click repetition unclearwhether the acousticreflex decay (ARD) seenin normalears is ratesfrom 50/s to 300/s[Rawool, Scand. Audiok 24, 199-205 (1995)]. relatedto frequency-specificchannels or whetherthe criticalvariable is the This investigationwas designedto evaluatethe effectof higherprobe timinginformation coded within the channels.This studyexamined ARD frequencieson theclick-evoked acoustic reflex thresholds and on therate- in subjectswith normalhearing and middle ear function.The degreeof inducedimprovement in theacoustic reflex thresholds. Twelve female and ARD wasmeasured for bothmodulated and unmodulated carrier frequen- six malesubjects with normalhearing participated in the study.lpsilateral cies of 500, 1000, 2000, and 4000 Hz with modulation rates of 50 - 400 acousticreflex thresholds were obtained from the left ear of eachsubject Hz. The dependentvariable was the half-lifeof the decayingreflex (ARD by presentingclicks at the repetitionrates of 60, 120, 180, 240, and 300 50%) over a 12-s stimulationinterval. Significant ARD was presentfor clicks/s.The resultswere obtainedfor three probe tone frequencies:226, high-frequencyunmodulated carriers, but not for low-frequencycarriers. 678, and 1000 Hz. All the subjectsshowed a decreasein admittancefor the For all listeners,ARD was diminishedfor all modulatedstimuli, suggest- 226-Hz probeand an increasein the admittancefor the 1000-Hzprobe. For ing that resistanceto ARD is mediatedby the temporalcharacteristics of the 678-Hz probe, some subjectsshowed an increasein admittanceand the stimulus.[Work supported by the AmericanHearing Research Foun- others showed a decrease in admittance. The acoustic reflex thresholds dation.] were significantlyelevated for the 678-Hz probetone. The rate-induced improvementin acousticreflex thresholds for eachsubject was calculated as the difference between the minimum and maximum acoustic reflex thresholds.This improvement (13 to 17 dB) wasnot significantly different 4pPP2. Is higher acousticenergy at faster rates necessaryfor the for the threeprobe tones. click-rate-induced improvement in acoustic reflex thresholds? Vishakha W. Rawool (Commun. Disord. & Special Education, BloomsburgUniv., Bloomsburg,PA 17815) 4pPP4. Effect of hearing impairment on the click-rate induced Ipsilateralclick thresholdscan improveby approximately21 dB, with facilitation of the acoustic reflex thresholds in older individuals. an increasein theclick repetition rates from 50/s to 300/s[Rawool, Scan& Vishakha W. Rawool (Commun. Disor& & Special Education, Audiol.24, 199-205 (1995)].When click-trains are presentedover the BloomsburgUniv., Bloomsburg, PA 17815) sameduration (e.g., 1.5 s), the numberof clickspresented at the lower ratesis lessthan the numberof clickspresented at the higherrepetition Ipsilateralclick thresholdscan improveby approximately2t dB, with rates.Thus thereis more total energyfor the higherrepetition rates. There- in increasein theclick repetitionrates from 50/sto 300/s[Rawool, Scand. fore, it has been proposedthat an importantfactor contributingto the Audiol.24 199-205 (1995)]in youngnormal individuals. This improve- thresholdadvantage for higher repetitionrates could be the numberof mentis significantlyreduced in olderindividuals [Rawool, J Gerontol. clicks. This invem•ation was designed to evaluate acoustic reflex thresh- Biol. Sci. (in press)].The currentinvestigation was designedto evaluate oldsat variousrepetition rates using a constantnumber of clicks(constant the effect of age-relatedhearing impairment on the rate-inducedimprove- acousticenergy). Ipsilateral acoustic reflex thresholdswere obtainedfrom mentin the acousticreflex thresholds.Ipsilateral acoustic reflex thresholds 19 normalfemale left ears by presenting300 clicks at the repetitionrates were obtainedfrom 60 older ears in the age range of 50 to 74 years.The of 50, 100, 150, 200, and 300/s. The frequencyof the probe tone was 226 subjectswere dividedinto four groups:(I) Normal.Hearing within normal Hz (85 dB SPL). The resultsshowed a significantimprovement (mean = limits (20 dB). (II) Mid high-frequencyimpairment. Hearing within nor- 17 dB) in acousticreflex thresholdswith the increasein repetition rates. mal limits up to 2 kHz, and an averageimpairment of 17.5 to 25 dB at 3, 2561 d. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society of America 2561 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, 6, and8 kHz. (lid Moderatehigh-frequency impairment. Hearing within emissionson the other hand may be interpretedas a type of impulse normal limits up to 2 kHz and an averageimpairment of 35 to 61 dB at 3, responseof a nonlinearsystem. The frequencyspecificity is comparatively 4, 6, and 8 kHz. (IV) Flat hearingimpairment. Hearing impairment across low. The interrelationof both types of emissionsis not completelyunder- the test frequencies.Ipsilateral acousticreflex thresholdswere obtained stooduntil now. To test the hypothesisof a commonorigin, patternsof from the left and/or right ear by presentingclicks at the repetitionrates of spectralfine structureof DPOAE andTEOAE resultsfrom normalhearing 50, 100, 150, 200, and 300 clicks/s.No significantdifferences were ap- subjectsare compared.In addition,the influenceof suppmssortones is parentin therate-induced improvement (11 to 14 dB) in theacoustic reflex investigatedin both experiments.Results will be discussedin connection thresholdsacross the four groups. to currentideas about wave-fixed and place-fixed generation of emissions alongthe cochlearpartition. 4pPPS. Middle ear of a llon: Comparison of structure and function to domestic cat. Gregory T. Huang, John J. Rosowski, Deborah T. 4pPP8. New evoked cochlear responses:Double chirp-evoked Flandermeyer,and William T. Peake (Dept.of Elec.Eng. and Comp. Sci. distortion products and double click-evoked otoacoustic emissions. and Res. Lab. of Elec., MIT, Cambridge,MA 02139 and Eaton-Peabody DouglasH. Keefe (BoysTown Natl. Res. Hospital,555 N. 30th St., Omaha, NE 68131) Lab., Mass. Eye and Ear Infirmary,243 CharlesSt., Boston,MA 02114) A novel family of evokedOAE responsescontrols probe distortion Acoustic and anatomical measurements have been made in a deceased using a stimuluspresentation method well-suited to researchand clinical lion (Pantheraleo) andcompared to measurementsin domesticcat (Felis applications.The family allowsa complementaryrepresentation between catus).The resultsare usedto testa modelin whichthe acousticimped- DP measurements and double click-evoked OAE measurements. Each anceat the tympanicmembrane (TM) is the sumof (1) theimpedance of stimulussequence includes three, equal-duration sub-sequences defined as the TM andossicular chain and (2) the impedanceof the middle-earcavi- follows:Sl(t) is a singlechirp or click,s2(t) = Esi(t- r) is a copyof s I ties. Impedancewas measuredat the TM in lion beforeand after manipu- with relativeamplitude c and delay r (0- 5 ms), and their superposition lationof the cavity structures;sound pressure in the cavitieswas measured s 12(t)= sl(t ) + s2(t). The pressureresponse to eachsub-sequence is p•, simultaneously.CT sectionsof the lion middleear wereused to reconstruct p2, and p•2, respectively.The doublechirp-evoked distortion product the tympanicring, the tympaniccavity, the bullar cavity,and the foramen (2ChDP) and doubleclick-evoked OAE (2CEOAE)are definedby that connectsthese cavities. A quantitativecomparison of thesestructures Po =P •2-Pl -P2. This subtractionof click responesis similarto Kemp showsthat ear dimensionsin the lion are roughlytwo timesthose in cats. et el. (1986)in eliminating the linear response, but differs in that particular Acousticmeasurements in the lion andcat arequalitatively similar, but the choicesof {st(t), r, E} improvemeasurements of 2CEOAEs at highfre- lion middle-carimpedance is generallysmaller. A six-elementanalog cir- quenciesby eliminatingtime-gating, and at low frequenciesby reducing cuit modelcaptures the main featuresof bothsets of measurements.The probedistortion, especially when two acousticsources are used. With a 16 acousticeffects of the size differencesare representedby changesin the kHz samplerate, 2ChDP and 2CEOAE responseshave been obtained from circuitmodel element values. In its ear, the lion is just a big pussycat. 350-7900Hz. A 2CEOAEspecial case is r=0, resultingin a wideband- [Worksupported by NIDCD.] width,single click-evoked OAE measurementwithout time-gating. Meth- odologicalrefinements in real-timeartifact rejection and nonlinearcoher- ence help reduce noise. [Work supportedby NIH Grant No. P01 DC00520.] 4pPP6. Relationship between the frequency microstructure of the pitch-level effect and the microstructure of synchronous evoked otoacousticemissions. Edward M. Bums (JG-15,Univ. of Washington, 4pPP9. The developmentof forward masking in human infants. Seattle,WA 98195) Lynne A. Werner (Dept. Speech& Hearing Sciences,Univ. of Washington,1417 NE 42rid St., Seattle,WA 98105-6246) The relationshipbetween the frequencymicrostincture of the behav- ioral thresholdand the frequencymicrostructure of the strengthof syn- It has beenpreviously reported that 3-month-oldhuman infants are chronousevoked otoacoustic emissions (SEOAEs) and delayedevoked moresusceptible to forwardmasking than are adults of the samespecies. otoacousticemissions is well documented[e.g., Zwicker and Schloth, J. Thepurpose of thepresent study was to determinewhether susceptibility Acoust.Soc. Am. 75, 1148-1154(1984)]. In a previousreport from this to forwardmasking declines between 3 and6 monthsof age.Six-month- laboratory[Burns et al., J. Acoust.Soc. Am. Suppl.I 80, S93 (1988)],it old infantswere trained to respondwhen they heard a trainof alternating has been shown that there is also a correlation between the microstructure burstsof a broadbandnoise and a 1-kHztone, but not when they heard the of thebehavioral threshold and the microstinctureof thepitch-level effect. noise bursts alone. The tone burst had 16-ms rise and fall times and no In this paper,the relationshipbetween changes in the microstinctureof steady-stateduration. The intervalbetween noise offset and tone onset, SEOAEsas a functionof thelevel of theevoking stimulus and pitch shifts At, was either 10, 25, or 200 ms; At was fixed for each infant. The onset as a functionof levelis examined.[Work supported by NIDCD andthe to onset interval between noise bursts was constantat 350 ms + At on all VirginiaMerrill BloedelHearing Research Center.] trials. The level of the noise was 65 dB SPL; its duration was 100 ms. The level of thetone was manipulated to definemasked threshold. Six-month- olds demonstratedabout 10 dB moreforward masking than adultsand about 10 dB less forward ma•king than 3 month-old• for •hort At, and 4pPP7. On the relation of distortion product and transient evoked aboutthe same amount of maskingas 3-month-olds for 200 msAt. [Work emission spectral fine structure. Stefau Uppenkamp, Manfred supportedby NIH.] Mauermann, and Birger Kollmeier (AG Medizinische Physik, FachbereichPhysik, Univ. Oldenburg,D-26111 Oldenburg,Germany) 4pPP10.Role of fundamentalfrequency differences in perceptionof Both distortionproduct emissions and transientlyevoked emissions simultaneousvowels by hearing-impairedlisteners. Kathryn Hoberg typicallyexhibit an individualfine structure,which seemsto be linked to Arehart,Catherine Arriaga King, and Kelly S. McLean (CDSSDept., thefine structure of thresholdin quietobservable in manynormal hearing Univ.of Colorado,CB 409, Boulder,CO 80309) subjects.However, the recording paradigm for bothexperiments is rather different.Narrow-band distortion product emissions are detectable during Thisstudy investigated the ability of normal-hearinglisteners and lis- continuousstimulation with two sinusolds.They representthe nonlinear tenerswith moderateto moderatelysevere sensorineural hearing loss to interactionof the two tonesin a stationarycondition. Transient evoked use differencesin fundamentalfrequency (F0) in the identificationof 2562 J. Acoust.Soc. Am., Vol. 99, No.4, Pt.2, April1996 131stMeeting: Acoustical Society of America 2562 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 monoticallypresented simultaneous vowels. Two psychophysical proce- 4pPPI3. Age-relatedhearing loss, temporary thresholdshift and dures•masked vowel identificationand double-vowel identification• were permanent threshold shift in four strains of mice. Yea-Wen Shiau, usedto measureidentification performance asa functionof F0 differences ErnestM. Weiler,Laura Kretschmer,Angel Dell'airs Ball (ML# 379, (0 through 12 semitones)between simultaneous vowels. The masked PsychoacousticsLab. CommunicationSci. & Disorders, Univ. of vowelidentification task yielded thresholds representing signal-to-noise Cincinnati,Cincinnati, OH 45221),and Mary Anne Baker IndianaUniv. ratiosat whichlisteners could just identify target vowels in thepresence of Southeast,New Albany,IN) a maskingvowel. Performancein the double-vowelidentification task was measuredby thepercentage of trialsin whichlisteners correctly identified A totalof 96 micefrom two inbredand two hybridstrains were tested bothvowels in a doublevowel. As previouslyreported, normal-hearing for TTS (temporawthreshold shift) and PTS (permanentthreshold shift) listenersshowed a sharpincrease in the abilityto separatesimultaneous usingelectrophysiological procedures for auditowbrain-stem responses. vowelsas F 0 differencesincreased from 0 to 1 semitone.Hearing-impaired Testingcontinued for up to 3 monthsfollowing 2 h of exposureto 110-dB listenerswere less effective in usingF0 differencesin theperception of broadbandnoise. The inbredand hybrid strains carrying genes for age- simultaneousvowels. Reasons for hearing-impairedlisteners' reduced per- relatedhearing loss showed TFS almostequal to theirPTS "thusantici- patingtheir tendencyto hearingloss." On the otherhand, the inbredand formanceprobably include differences in theirability to usespectral and hybridstrains not carrying those genes showed considerable recovery from temporalcues across different frequency regions in their perceptionof theiroriginal TTS losses.Those with age-related hearing genes were very complex-tonepitch. [Work supported by DeafnessResearch Foundation.] susceptibleto noise-inducedPTS. An additionaleffect was the presence of strongcorrelations between TTS and PTS for both inbred strains,but no correlationfor the two hybridstrains. Noise exposure histow plays a role in the noncorrelationsbetween TFS and PTS typicallyfound in humans. 4pPPll. Discriminabilityof two-componentcomplex tones by Could genesinfluence correlation between Trs and PTS in humans? normal-hearingand hearing-impairedlisteners. KathrynHoberg Arehartand Peninah S. Fine (CDSSDept., Univ. of Colorado,CB 409, Boulder,CO 80309) 4pPP14. Hearing and developmentimpairment in Down-syndrome The discriminabilityof complimentarytwo-tone complex tones (Voel- children. M. AngelaG. Feitosaand RosanaM. Tristao (Institutode ckerpairs) was investigated in normal-hearingand hearing-impaired lis- Psicologia,Univ. Brasi]ia,Brasilia, DF, 70910-900, Brazil) tenersusing a 2AFCtask. A two-componentcomplex consists of twopure tones(f• ,f: whichdiffer in frequency(Af Hz) and intensity(AI dB). A growingnumber of studieshave shown that Down-syndrome per- WhenAI=0 dB, the pitchof thecomplex corresponds to the centerfre- sonshave a highincidence of auditorydeficit and slow language develop- quency(f•) wherefc=(f• +f_Q/2. When AI>0 dB, the pitchshifts to- ment.Down-syndrome children were investigated with respectto (a) hear- ward the moreintense component. In one toneof a Voelckerpair, the ing level, (b) languagedevelopment, (c) globaldevelopment, and (d) intensityof f•(l•) is greaterthan the intensityof f2(12) by AI; in its environmentalinteraction. Fifty-one children, 6-47 monthsold, were ob- complement,1•<12 by AI. Discriminabilityof the pitchesof Voelcker served,22 of whom had Down syndrome.Controls included 13 children pairswas measuredas a functionof Af (10 through1000 Hz), for three withoutdiagnosis of mentalimpairment, and 16 childrenwith mentalim- f,.s (1000,2000, 4000 Hz) andfor two Als (1, 3 riB).Normal-hearing pairmentdue to etiologiesother than Down syndrome.None of the sub- listeners'results were similar to previousresults [Feth et al., J. Acoust. jectshad a previousdiagnosis of hearingloss. Relations among levels of Soc.Am. 72, 1403-1412 (1982)]. Thresholdsfor discriminationof Voel- hearing,global and languagedevelopment, home stimulation,and risk factorsfor hearingloss were analyzed. The Down-syndromegroup showed cker pairsby hearing-impairedlisteners were abnormally large across all significantlyelevated auditory thresholds and a largernumber of patho- centerfrequencies. Results will be discussedin termsof predictionsof logical findingsin the externaland middleears, as comparedto other EWAIF/IWAIF models[Anantharaman et al., J. Acoust. Soc. Am. 94, groups.It alsoshowed lower levels in languagedevelopment, as compared 723-729(1993)] and hearing-impaired listeners' deficits in usingtemporal to globaldevelopment; and shortened latencies of wavesI andV in BERA. cuesin pitchperception. [Worksupported by CNPqand CORDE.] 4pPPI2. Acousticproperties of the chinchillapinna and ear canal. 4pPP15.The effectof head protectorson warningsound perception William J. Murphyand Rickie R. Davis (Bioacoust.and Occup.Vib. in noisyworkplaces. Martin Fortin,Raymond Hetu, HungTran Quoc, Sect.,Natl. Inst.for Occup.Safety and Health, MS C-27, 4676 Columbia and StepbaneDenis (Grouped'acoustique de l'universitede Montreal, Pkwy.,Cincinnati, OH 45226-1998) C.P. 6128, Succ.Centre-ville, Montreal, PQ H3C 3J7, Canada) Measurementsof the acoustictransfer function (ATF) of the pinnaeof The acousticresponse of head protectorswas assessedby meansof a 4 chinchillaswere comparedwith the auditow-evokedpotential (AEP) mecano-acoustichead simulator.The following protectivedevices were hearing thresholdsof 16 chinchillasmeasured in free field and with insert tested:welders' mask, fire-fighterhelmet, aluminizedhood, leatherhood, earphones.The ATF was measuredin anesthetizedchinchillas in a far-field sand-blastinghood, dust protection hood, and emergencyrespirator. The conditionin a semi-anechoicroom. Probe microphone measurements were tests were conducted in an hemi-anechoic chamber with a wideband noise collectedjust outsidethe pinnaand at the tympanicmembrane. The ATF presentedat 100 dB SPL. The effect of 36 horizontalcombined with 13 exhibiteda broadresonance between 2 and6 kHz with abouta l0 dB gain. verticalangles of incidencewas assessed.Generally speaking, head pro- tectorsare responsiblefor insertiongains of 5 to 10 dB in the low fre- The chinchillaswere monauralized and had a chronicelectrode implanted in the left inferior colliculus. The animals were awake and restrained dur- quenciesand for insertionlosses of up to 30 dB in the high frequencies. The acousticresponse of head protectorsconsiderably varied with the ing the AEP testing.The AEP measurementswere averagedfrom 512 angleof incidence.With the welder'smask, when the sourceis coming presentationsof a toneburstat 0.5, 1, 2, 4, and 8 kHz. AEPscollected with from the rear, a systematicgain is observedat almost all frequencies;the insertearphones were calibrated with a probemicrophone positioned near maskacts as a low-passfilter in the frontalquadrant. These findings hold the tympanicmembrane. The differencesin the AEP hearingthresholds implicationswith respectto health and safety issues.In term of risk of measuredin the differentconfigurations exhibited a 10 dB resonanceat 4 hearingdamage, the wearingof a headprotector may significantlyincrease kHz. The agreementbetween the ATF and AEP-derivedtransfer function the noiseexposure level of a worker.In termsof safety,such devices may suggestedthat the thresholddifferences from the two testingconfigurations interferewith signal detectionin noise and soundsource localization. couldbe accountedfor by the pinnaand ear canal gain. [Worksupported by IRSST.] 2563 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April1996 131st Meeting:Acoustical Society of America 2563 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 4pPP16. Physiological correlates of the time-intensity trade in ABR abnormalitiesassociated with conductiveimpairment are present. auditorylate responses.Joelie Rednet and Ann Clock Eddins (Dept.of Specifically,in thecases of unilateraldisease,there is a significantdiffer- Speech and Hearing Sciences, Aud. Phys. Lab., Indiana Univ., encebetween ears in the wavesI-V interpeaklatency which is indepen- Bloomington,IN 47405) dentof audiometricasymmetry. These data may indicate that an elementof plasticityexists in themature auditory system. [Work supported by NIH Numerouspsychophysical studies have demonstratedthat behavioral NIDCD.] detectionthresholds decrease with increasingsti•nulus duration, often re- ferredto as the time-intensitytrade. Few studies,however, have evaluated the physiologicalcorrelates of this tradingrelationship. The purposeof the presentstudy was to examine the effect of stimulusduration on evoked 4pPP19. Estimates of spectral weights and internal noise in the potentialthresholds known as the auditorylate response(ALR). Behav- discrimination of spectral variance. Robert A. Lutfi and Eunmi Oh ioral and ALR thresholds were estimated for 1000 and 4000 Hz tone bursts (Dept. of CommunicativeDisorders, Univ. of Wisconsin,Madison, WI at 8, 16, 32, 64, and 128 ms in five normal-hearing,young adults. Evoked 53706) responseswere recorded in 2-dB steps from 20 dB to -4 dB SL re: behavioral threshold. ALR threshold was estimated as the lowest level at An experiment was conductedto measurethe relative contributionof which the NI-P2 complexwas visuallydetected by two independent spectralweights and internalnoise in the discriminationof spectralvari- judges.Preliminary results show that both behavioral and ALR thresholds ance.The stimuliwere simultaneous tone complexes comprised of the six decreasedas a functionof increasingduration. For the 1000-Hz stimulus, octavefrequencies from 250 to 8000 Hz. On eachpresentation the levels bothALR andbehavioral thresholds decreased by approximately23 dB of componentsin dB weredrawn independently and at random from one of HL overthe range of durationstested. Average ALR andbehavioral thresh- two normaldistributions having identical means but differentvariances oldsfor the 4000-Hz stimulusdecreased by about19 dB HL. Theseresults (o'• = 1 dB, trs = 2-10 dB). In the standard2IFC procedure,the listen- showthat the time-intensitytrade can be demonstratedphysiologically er's taskwas to choosethe complexhaving the greatervariance in com- usingthe auditorylate response. ponentlevel. The shapeof the psychometricfunction for all five listeners was markedlydifferent from thatof an observerlimited only by additive internalnoise. It wasconsistent with an observerthat gives weight to only one or two componentsin the complex.This result,however, was incon- 4pPP17. Detection of frequency-modulated signals by sistentwith the weightingfunctions computed from the trial-by-trialdata cochlear-implantusers. Ina Rea Bicknelland Lawrence L. Feth (Dept. from these listeners. Both measures can be reconciled if it is assumed that of Speechand HearingSci., Ohio StateUniv., Columbus,OH 43210) listenerweights vary from trial to trial, or equivalentlythat observations are corruptedby multiplicativerather than additive internal noise. [Work Many cochlear-implantusers show postoperative improvement in the supportedby NIDCD RO1 DC01262-04.] abilityto hearspeech but most rely on lip-reading to understandspeech. To determineif thislimitation on speechperception relates to impairedtem- poralresolution, and, thus,an inabilityto trackrapid frequencychanges which are characteristicof speech,temporal resolution thresholds (TRT) of 4pPP20. Intrinsic envelope fluctuations and modulation-detection adultimplant users were determined by measuringtheir ability to discrimi- thresholds for narrow-band noise carriers. Totsten Dau, Jesko natebetween a glidesignal, a sinusdidlinearly modulated in frequencyand Verhey (GraduiertenkollegPsychoakustik, Fachbereich Physik, Univ. a stepsignal, a sinusdidtraversing the samefrequency range but in two to Oldenburg,D-2611101denburg, Germany), and Armin Kohlrausch (Inst. fivediscrete steps. Performance of implantedsubjects was extremely vari- Pemept.Res. (IPO), Eindhoven,The Netherlands) able,but, generally,their TRTs werehigher than those of age- and sex- matchednormal-hearing controls. At certainfrequencies and sweepex- Thiscontribution summarizes analytical properties of envelopemodu- tents,no implantedsubjects were ableto distinguishbetween step and lationspectra of bandpassnoise signals, which are relevant for thedepen- glidesignals of durationshorter than 300 ms. When the signal step number denceof amplitude-modulationthresholds on modulationrate and noise wasno greaterthan two, one subject, using a Spectraspeech processor, had carrierbandwidth. Lawson and Uhlenbeck [Threshold Signals (McGraw- TRTsnear the 10 msupper limit of thecontrol TRTs. Extended frequency Hill, NewYork)] showed in 1950that the modulation spectrum, i.e., the sweepsof 1350-1500 Hz with centerfrequencies of 3300-3400 Hz re- powerspectrum of the linearenvelope of a bandpassnoise, has an ap- sultedin nearlynormal TRTs for twoof theimplant users. [Work supported proximatelytriangular continuous spectrum besides the dc peak.For a by the Dayton, OH VAMC and a grant from AFOSR.] constantoverall level of a noiseband, the total powerof intrinsicnoise fluctuations,i.e., the total areaunder the triangle,remains constant. The modulationspectrum, however, becomes broader with increasingnoise bandwidth. For low modulation rates, this leads to a reduction in intrinsic 4pPP18. Auditory brain-stem responsesin adults with chronic modulationpower. For higher modulationrates, the intrinsicmodulation conductivehearing loss. Michael O. Ferguson,Raymond D. Cook, powerincreases. Simple analytical calculations are presented which com- JosephW. Hall Ill, JohnH. Grose,and Harold C. Pillsbury (Div. of putethe integratedmodulation power of the noisewithin the transfer func- Otolaryngol.,Head and Neck Surgery,Univ. of North Carolina,610 tion of a hypotheticalmodulation filter. For a set of carrier bandwidths Burnett-Womack,CB# 7070, ChapelHill, NC 27599) between1 and6000 Hz andfor signalmodulation of 5, 25, and 100Hz the calculatedvalues of overallmodulation power are compared with experi- The ABR is a brief latency,electrophysiologic response that reflects mentally obtainedmodulation detection thresholds, and with resultsfrom •ynchronou•neuronal activity from the auditory-nerveand brain stem simulations of an auditory model. structures.Investigations have shownthat childrenwith early conductive impairmentexhibit abnommlities in theirABR, suggestingthat the nervous systemhas an element of plasticityduring critical periods of development. However, no similar research has been undertaken on adults to determine 4pPP21.Intensity weighted average of instantaneousfrequency whetherABR abnormalitiesassociated with chronicconductive impair- computationsusing time-frequencyrepresentations. Jayanth N. mentalso exist in thispopulation. This study addresses that question by Anantharaman,Ashok K. Krishnamurthy(Dept. of Elec.Eng., Ohio State investigatingthe ABR in a groupof adultswith chronicconductive loss Univ.,Columbus, OH 43210),and Lawrence L. Feth (OhioState Univ., anda controlgroup of normal-hearingadults. The goalwas to determine Columbus,OH 43210) whetherchronic conductive hearing loss in adultswould result in similar abnormalABR measurementsasseen in thejuvenile population. Subjects The intensityweighted average of instantaneousfrequency (FWAIF) were evaluatedby comparingABR interpeaklatencies between waves I hasbeen used to modellistener performance in complex signal discrimi- andHI andwaves I andV. In addition,interaural latency differences were nation[Anamharaman et al., J. Acoust.Soc. Am. 94, 723-729(1993)]. assessedin casesof unilateraldisease. Preliminary results suggest that Short-term[Krishnamurthy and Feth, J. Acoust.Soc. Am. 93, 2387(A) 2564 J.Acoust. Soc. Am., Vol. 99, No. 4, Pt.2, April1996 131stMeeting: Acoustical Society of America 2564 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 (1993)]and multichannel [Mokheimer et al., IEEEProc. First Intl. Conf. 4pPP24.Discrimination of harmonic-and log-spacedprofiles and of on ElectronicsCircuits and Systems, Cairo, Egypt (1994)] implementa- staticand dynamicprofiles by goodand poorprofile listeners. Ward tionsof themodel have been proposed. Time-frequency representations R. Drennanand CharlesS. Watson (Dept. of Speechand Hear. Sci., (TFRs)offer a convenientway to process signals over the time-frequency IndianaUniv., Bloomington, IN 47405) plane.TFRs canbe usedto computethe IWAIE TFRs canalso be usedto Most profileexperiments have employed static profiles with logarith- computethe short-termIWAIF and the mulfi-channelIWAIE Thesewill be mic spacing.Many naturally occurring sounds have harmonic spacing and presentedalong with preliminarydevelopments of both the short-term vary dynamicallyin time.Watson and Drennan [J. Acoust.Soc. Am. 97, IWAIF andthe multichannel IWAIF. The necessaryproperties of theTFRs 3272(A) (1995)] examinedprofile discrimination using both static and to be suitablefor usein thesemodels will be discussed.[Work supported frequency-glideprofiles with harmonicand logarithmiccomponent spac- by a grantfrom AFOSR.] ing. Subjectsdetected an intensityincrement in the middlecomponent of 1l-component, 400-ms profileswith a frequencyrange of 200-2200 Hz. Differencesamong the sevensubjects were considerablylarger than dif- ferencesamong the typesof profiles,confirming earlier observations of a 4pPP22.A quantitativeprediction of modulationmasking with an largerange of abilitiesto discriminateprofiles. Another experiment was optimal-detector model. Torsten Dau, Birger Kollmeier thereforeconducted to estimatethe distributionof profilediscrimination (GraduiertenkollegPsychoakustik, Fachbereich Physik, Univ. Oldenburg, abilitiesfor normal-hearinglisteners. Forty-six subjects were screened us- ing static-logprofiles. The distributionof thresholdswas roughlynormal D-26111 Oldenburg,Germany), and Armin Kohlrausch (Inst. Perc.Res. with a rangeof -2 to -26 dB (signallevel relativeto componentlevel) (IPO), Eindhoven,The Netherlands) and an s.d. of 4.8 dB. No dichotomyin profilediscrimination ability was found.Subjects were selectedfrom eachtail of the distributionand tested A multichannelmodel is discussedwhich describes effects of spectral usingthe static-log,static-harmonic, dynamic-log, and dynamic-harmonic andtemporal integration in amplitude-modulationdetection and masking. profiles.The orderof presentationof conditionssignificantly affected the Envelopefluctuations within each auditory channel are analyzedwith a results;however, whatever the order,static profiles yielded lower thresh- modulationfilterbank. The parametersof the filterbankare the samefor all oldsthan the frequency-glideprofiles. [Work supportedby NIH/NIDCD andAFOSR.] auditoryfilters and were adjusted to allowthe modelto accountfor modu- lationdetection and modulation masking data with narrow-bandcarriers at a highcenter frequency. In the detectionstage, the outputsof all modula- tion filtersfrom all excitedperipheral channels are combinedlinearly with 4pPP25. Distinctiveness and serial position effects in tonal optimalweights. To integrateinformation across time, a "multiple-look" sequences:Combining DDT and PTD. Aimee M. Surprenant (Dept. strategyis implementedwithin the detectionstage. Model predictionsare Psychol.Sciences, Purdue Univ., W. Lafayette,IN 47907) comparedwith literaturedata from Houtgast[J. Acoust. Soc. Am. 85, 1676-1680(1989)]. The following three conditions were reproduced with The proportion-of-the-totalduration rule (PTD) [Kidd and Watson,J. Acoust.Soc. Am. 92, 3109-3118(1992)] states that the detectabilityof a a deviationof less than 3 dB betweenexperiment and simulation.(1) changein a componentof a tonal sequencecan be predictedby the dura- Maskingof test modulationsin the range2 to 64 Hz by a narrow-band tion of the changedcomponent relative to the sequenceas a whole. A maskermodulation at 4, 8, or 16 Hz. (2) Modulationmasking as a function similaridea has been used in dimensionaldistinctivehess theory (DDT) of the masker-modulationlevel. (3) Modulationmasking as a functionof [Neath,Mem. Cognit.21, 689-698(1993)] to accountfor primacy,re- the masker-modulation bandwidth. The results from the simulations further cency,and other serial position effects in memory.An item will be remem- supportthe hypothesisthat amplitude fluctuationsare processedby bered if it is more distinctalong somedimension relative to possible modulation-frequency-selectivechannels. competitors.These experimentsexplore the relation betweenDDT and PTD by examiningthe effectof inter-stimulusinterval (ISI) on the detec- tion of a changein one toneof a tonalsequence for eachserial position in the sequence.Results show that, with increasingISI, performanceon the 4pPP23. Comodulation masking release as a function of masking first items increaseswhereas performance on the final items decreases,as noise-band temporal envelope similarity in normal hearing and predictedby DDT. In addition,the interactionof PTD and ISI was ex- plored for each serial position.This researchcombines theories proposed cochlear impaired listeners. Lee Mendoza, Marl L. Schulz, and in the psychophysicaland memoryareas and suggeststhat a comprehen- RichardA. Roberts (Dept.of SpeechPathok and Audiok, Univ. of South sive principlebased on relativedistinctivehess can accountfor both per- Alabama,UCOM 2000, Mobile, AL 36688) ceptualand memoryeffects. Thresholdsfor a pure-tonesignal (1000 Hz) wereobtained from both normalhearing and hearing-impairedlisteners in a variety of maskercon- ditions.Masking stimuli consistedof five Gaussiannoise bands,each 20 4pPP26. Temporal integration as a function of masker bandwidth. Hz wide, and centered on 500, 750, 1000, 1250, and 1500 Hz. Two such AndrewJ. Oxenham (Inst. for Percept.Res. (IPO), P.O. Box 513, 5600 MB Eindhoven,The Netherlands) base stimuli were created. In the first stimulus set, all noise bands had the sametemporal envelope (comodulated). In the secondset, each noise band Thresholdswere measuredfor a 6-kHz sinusold,temporally centered in was generatedindependently of the other bands,and thus each had inde- a 500-msmasker which was either a bandpassGaussian noise (20 dB SPL pendenttemporal envelopes. Additional maskingstimuli were generated spectrumlevel) or a 6-kHz sinusold(40 dB SPL).A notchednoise centered by combining the comodulatedand independentbands at specific on 6 kHz preventedthe useof off-frequencycues. The signal,gated with comodulated/independentintensity ratios (CIR = 25, 20, 15, 10, and 5 2-msramps, ranged in half-amplitudeduration from 2 to 300 ms.The noise dB), with overall level of the combined noise bands held constant.The bandwidthwas arithmeticallycentered on 6 kHz and was variedfrom 60 result of increasingCIR was a progressiveincrease in the similarity of Hz to 12 kHz. For maskerbandwidths below 300 Hz, the slopeof inte- grationfor signaldurations between 2 and 20 ms decreasedwith decreas- temporal envelopes of the noise bands masking the signal. Compared to ing maskerbandwidth. For the tonal masker,increasing signal duration thresholdfor the pure-tonesignal in independentbands of noise,threshold from 2 to 20 ms had no effect on threshold. These results cannot be steadily decreasedas the CIR increasedfor normal hearing listeners. accountedfor by lowpass-filteror temporal-windowmodels of temporal Cochlear-impairedsubjects also showed decreased threshold with increas- integrationor resolution.Instead, it is proposedthat the auditory system ing CIR; however,the improvementwas seento plateauat relatively low performsa spectralanalysis of the stimulusenvelope, so that the rapid CIRs. [Work supportedby DRF and USARC.] fluctuations(high modulationfrequencies) introduced by gatingthe signal 2565 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society of America 2565 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 canbe usedas a cuefor brief signalsin narrowbandnoise and tones. For identicalfor all AF. Thresholdswere higher in the C condition,thus broadbandmaskers, this cue is not available due to the masker's inherent showinga comodulationdetection difference (CDD). The CDD wasgreat- rapidenvelope fluctuations. [Work supported by theWellcome Trust.] est for AF between 400 and 600 Hz. A second set of conditions was used in which eitherone, both,or noneof the maskingbands was comodulated with the signal.This was donefor threedifferent masker spectrum levels at a AF of 600 Hz. The resultssuggest that the CDD seen in the first 4pPP27. Sinusoidalamplitude modulation thresholds as a function experimentwas mainly due to the upwardspread of maskingfrom the of carrier frequency and level. Ralf Fasseland Armin Kohlrausch lower bandand not to an across-channelgrouping effect. (Inst. for PerceptionRes., P.O. Box 513, NL-5600 MB Eindhoven,The Netherlands) Modulation detection thresholds for sinusoidal carriers were obtained 4pPP30. Amplitude-modulation depth discrimination of a sinusoidal for a widerange of modulationrates (10-1600 Hz) asa functionof carrier carrier. JungmeeLee andSid P.Bacon (PsychoacousticsLab., Dept. of frequency(i, 3, 5, 8, and 10 kHz) andcarrier level (30, 45, 60, and75 dB Speechand Hearing Sci., Arizona State Univ., Tempe, AZ 85287-1908) SPL). At low modulationrates, between l0 and about100 Hz, thresholds were roughlyconstant. For highermodulation rates, thresholds were de- Discriminationof the changein depthof sinusoidalamplitude modu- pendenton carrier frequency. For the lowest carrier frequency (l kHz),the lationwas investigated for a 4000-Hz carrier.The just noticeablechange in modulationsidebands were already spectrally resolved at a modulationrate the modulationdepth (Am) wasmeasured as a functionof (1} standard of 100 Hz and thusthresholds decreased with increasingmodulation rate. modulationdepth (m = 0.1, 0.18,or 0.3}, (2) modulationrate (f,•= 10,20, For the highercarder frequencies,the sidehandswere resolvedonly at 40, or 80 Hz), and (3) stimulusduration (T=25, 50, 100, 200, 400, or 800 highermodulation rates, due to theincreasing auditory-filter bandwidth. In ms}.For modulationrates less than 80 Hz, threshold(Am) washigher at thesecases, thresholds initially increasedwith increasingmodulation rate a standarddepth of 0.3 thanat theother standard depths. When f,n = 80 Hz, with a slopeof about8 dB/oct.The thresholdcurves show a differentshape the threshold was almost the same across different standard modulation than thoseobtained with broadbandnoise carriers.In general,thresholds depths.For all standarddepths and modulationrates, the thresholdde- decreasedwith increasingcarrier level at any given carrierfrequency up to creasedby more than a factor of 2 as stimulusduration increased to a at least 60 dB SPL. For one subjecta saturationof thresholdsat medium certainT (criticalduration). For durationslonger than the criticalduration, carrierlevels was observed. At very low carrierlevels of 20 dB SL, thresh- the thresholddecreased only slightly or remained constant.The critical olds tendedto increasewith increasingmodulation rate alreadybelow 100 durationcorresponded to about four cyclesof modulation.Psychometric Hz. functions were measured for different stimulus durations. The data were evaluatedin termsof a multiple-looksmodel. [Work supportedby NIDCD.] 4pPP28. Across-channel processes in frequency modulation detection. Shigeto Furukawaand Brian C. J. Moore (Dept. of ExperimentalPsych., Univ. of Cambridge,Downing St., CambridgeCB2 4pPP31. Detection of tones in modulated noise: Effects of masker 3EB, UK) level and masker depth. Sid P. Bacon, JungmeeLee, Daniel N. Peterson,and Dawne Rainey (PsychoacousticsLab., Dept. of Speechand This studyexamined whether the detectionof frequencymodulation HearingSei., Arizona StateUniv., Tempe,AZ 85287-1908} (FM) on two ca,tiersdepends on thecoherence of the FM acrosscarriers. Psychometricfunctions were measuredfor detectingsinusoidal FM of It is possibleto estimatetemporal resolution at discretespectral loca- carrierswith frequencies1100 and 2000 Hz. The modulatorsfor the two tionsby subtractingthe maskedthreshold produced by a modulatedmasker carderswere either in phase(coheren0 or in anti-phase(incoheren0. The fromthat produced by anunmodulated masker (the difference is referredto modulationrate waseither 2.5, 5, or l0 Hz. One or morecycles of modu- as the modulated-unmodulateddifference, or MUD). This paradigmmay lationwere used. The modulationof eachcarrier was equally detectable, as be especiallyuseful for measuringtemporal resolution in subjectswith determinedin a preliminaryexperiment. A continuouspink noiseback- hearingloss, provided that the MUD is independentof level.The purpose groundwas usedto mask the outputsof auditoryfilters tunedbetween the of the presentstudy was to examinethe MUD as a functionof maskerlevel two cartier frequencies.Detectebility was betterfor coherentFM thanfor at several signal frequencies.In the first experiment,the sinusoidally incoherentFM. The effect of FM coherencewas greatestat the lowest amplitude-modulatedmasker had a depth(m) of 1.0.The MDD increased modulationrate, possibly indicating that phase locking plays a role [B.C. by as much as 15 dB as the spectrumlevel of the maskerincreased from L Mooreand A. Sek, J. Acoust.Soc. Am. 97, 2468-2478 (1995)].The 0 to 40 dB SPL. In the secondexperiment, the modulatedmasker had a detectabilityof the coherentFM was well abovethe value predictedon the depthof 0.75 or 1.0. When the maskerdepth was 1.0, the MUD increased assumptionthat informationfrom the two camierfrequencies was pro- with increasingmasker level, as in experimentone. When it was 0.75, cessedindependently and combinedoptimally. These resultsimply the however,the MUD -- thoughreduced -- was essentiallyindependent of existenceof oneor moremechanisms sensitive to FM coherence.[Work maskerlevel. These results suggest that a maskerdepth of 0.75 may be supportedby the MRC(UK), the BritishCouncil, and an ORS awaxd.] usedto comparetemporal resolution between normal-bearing and hearing- impairedsubjects without being complicated by effectsof maskerlevel. [Worksupported by NIDCD.] 4pPP29. Within and across channel procea½,escontributing to comodnlation detection differences. StephenJ. Borrill and Brian C. J. Moore (Dept.of ExperimentalPsych., Univ. of Cambridge,Downing St., 4pPP32.Effects of noiseon the hearingsystem. KingChung (Dept.of CambridgeCB2 3EB. UK) Audiol.,Northwestern Univ., 2299 N. CampusDr., Evanston,IL 60201) The thresholdfor detectionof a narrow-bandnoise signal was deter- This paper providesan overview of effectsof noiseon the hearing minedin the presenceof a maskerconsisting of two synchronouslygated system.Animal research has shown that excessivenoise exposure results 20-Hz-wide bandsof noise with a spectrumlevel of 65 dB which were in decreaseof bloodflow in striavascularis, alteration in permeabilityof coraodulated.The maskerswere spacedby AF Hz aboveand belowthe ionsin reticularlamina, swelling/rupture of hair cells,disarrangement or signalfrequency (1500 Hz). A low-passnoise was used to maskany com- lossof stereocilia,broken tip links and sidelinks between the stereocilia, binationproducts. Three conditions were tested:signal and maskerenve- swellingof afferentdentrides, rupture of the organof Corti, decreasein lopescorrelated (C), signaland maskerenvelopes uncorrelated (U), or tectorialmembrane thickness, and increase in itscompliance, etc. After the sinusoidalsignal of the sameoverall level (S). AF rangedfrom 2130to exposure,the stereociliamay becomea fanlikestructure or fusetogether to 1400 Hz. Maskedthresholds for the IJ and S conditionswere essentially forma giantstereocilia. In a severelydamaged cochlea, the haircells may 2566 d. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April1996 131st Meeting:Acoustical Society of America 2566 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 be replacedby someundifferentiable scar tissue. The pharyngealprocesses ologicalchanges include disruption of the cochlearactive process, changes of the Deiter's cells and other supportingcells enlargeto seal off the in cochlearpotentials, broadening of the turningcurve of basilarmem- endolymphand perilymphion boundaries.The neuralfibers and ganglion braneand spiral ganglionneurons, and hearingloss are also observed. cells may graduallydegenerate and tonotopicreorganization in dorsal Remedialprocedures, e.g., regenerationof hair cells and "preexposure cochlear nucleus follows. Along with these anatomical damages,physi- conditioning"are also discussed. THURSDAY AFTERNOON, 16 MAY 1996 CELEBRATION A, 1:30 TO 5:10 P.M. Session4pSA Structural Acousticsand Vibration: Memorial Sessionfor Ellyn Richards JosephM, Cuschieri,Chair Departmentof OceanEngineering, Center for Acousticsand Vibration,Florida Atlantic Universi.ty, Boca Raton, Florida 33431 Chair's Introduction--l:30 In vited Papers 1:35 4pSA1.The foundationof the Instituteof Soundand VibrationResearch. Peter O. A. L. Davies (Inst.of Soundand Vib. Res., Univ. of Southampton,Southampton SO17 1BJ,UK) Thereare few people for whoma flourishingresearch institution provides a living memorial. That the ISVR wasborn at all was dueto thecharacteristic and legendary "ten-year vision" of its founder,Professor EIfyn Richards. In the 1950's,as Professor of Aeronauticsat Southampton, he perceived that noise and vibration were to becomea "disease"of newtechnology, for which traditionalapproaches would be no cure. Thus he founded a new applied science, now known as engineering acoustics and vibration. Thismemorial paper describes the first two decades of boththe foundation and early development of the ISVR. It concludeswith a brief appraisalof its currentactivities. 2:00 4pSA2.Jet noise:The early history. GeoffreyM. Lilley (Dept.of Aeronauticsand Astronautics, Univ. of Southampton, SouthamptonSO 17 IBJ, UK) Theinvention of thejet engineand its development during World War II asthe propulsive system for fighter aircraft led aircraft designersin the late 1940s to investigateitsuse as the power plant for civil air transports. The aim was improved speed, economics, andefficiency over that of slowerpropellor-driven aircraft. However two major problems existed, (a) itshigh fuel consumption, and (b) itsnoise at full take-offpower. Innovative University jet noiseresearch in theUK in thelate 1940s and early 1950s quickly led tostrong industry-university collaboration. This resulted in thedevelopment of the corrugated or lobed nozzle for jet noisereduction andlater to theintroduction of the bypass engine achieving significant reductions in both specific fuel consumption and jet noise reduction.The experiments byR. Westleyand G. M. Lilleyat Cranfield and by Professor E.J. Richards and A. Powellat Southampton University,Professor SirJames Lighthill's theoretical studies atManchester University, and the skill of F.B.Greatrex and his team at Rolls-Royceallcontributed tothis successful revolution incivil aircraft design. The paper discusses therapid development ofthis early jet noiseresearch and the corresponding complementary work in theUSA. 2:25 4pSA3,E. J. Richardsand jet noiseresearch at Southampton1951-56, Alan Powell (Dept. of Mech.Eng., Univ. of Houston, TX 77204-4792) EllynRichards became the first Professor ofAeronautical Engineering atUniversity College, Southampton, inSeptember 1950 and heimmediately began planning for jet noiseresearch. The author joined him in January1951, remaining until August 1956. Some eventsof that period are reviewed. With Richards' boundless energy and infectious enthusiasm, hisindispensible helpwith more than a touchof impatience--kindlytoward the author, less so for administrativebarriers--progress wasremarkably rapid, though the experimentalapparati were in most respects very modest bylater standards. Theeighth power law for turbulent jetnoise power (and theawkward lack of proportionalityof peak frequency with velocity), the screech of chokedjets and supersonic edgetones were all discoveredinthe first year. Feedback theories for the latter two, pulse jet noise, and other investigations such as shock wave interaction andmeans of reducingscreech were soon to follow.Acoustically inducted fatigue (AIF) of aircraftstructures caused by jet noisewas predictedand soon after was found to occur in practice. Richards played some role in all of these topics, but his innumerable ideas and wideningnoise interests could not possibly all be addressedin thatperiod. 2567 d.Acoust. Soc. Am., Vol. 99, No.4, Pt.2, April1996 131stMeeting: Acoustical Society of America 2567 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 2:50 4pSA4.Encounters I had with Professor Richards. G. Maidanik(David Taylor Model Basin, NSWC, Bethesda, MD 20084-5000) I met ProfessorRichards for the first time in 1951, when 1 was consideringSouthampton University for undergraduatestudies. He never rememberedit, I have. The secondtime I met ProfessorRichards was in 1962 in Boston,and then again and again over the subsequentyears. I wasalways impressed by his keenscientific sense and his friendliness,the markof a greateducator, which he certainlywas. 3:15-3:30 Break 3:30 4pSAS.Recalling some contributions by Ellyn Richards. StanleyE. Dunn (Dept. of OceanEng., FloridaAtlantic Univ., Boca Raton, FL 33431) ProfessorElfyn Richardsenjoyed a longand unusually notable career which ranged over engineering,education, and public policy development.The scopeof his impactwas international and, as the HonoraryFellow awardby the Societyproclaims, of particular importancein the United States.Toward the end of his careerhe made himselfavailable to work with the OceanEngineering Departmentat FloridaAtlantic University. That interactionwas to havea profoundimpact on the programand its subsequentsuccess in a numberof areas.This papershares the highlightsof ProfessorRichards' collaboration with the departmentand discussesthe benefitswhich were so dependenton the uniquequalities of his character. 3:55 4pSA6.Structural damping by granularmaterials. ArcanjoLenzi (Lab.de Vibmcfese Acfistica,Dept. Eng. Mec•nica, Univ. Federalde SantaCatarina, C.P. 476, CEP 88037-140,Florianopolis SC, Brazil) Studieson a usefuland rarely useddamping technique, the filling of cavitycomponents with granularmaterials, are presented. Experimentalstudies show regions of maximumdamping caused by standingwave formationin the material.The first maximum occurswhen the internaldimension of the cavityis equalto onequarter of the longitudinalwavelength. The tuningof optimum dampingto any desirable frequency requires accurate knowledge of thewave speed. Experiments show that wave speeds decrease with amplitudewhen strains reach values higher than about l0 -6. Thisis caused by gross slip taking place at contactswhich breaks the mainstructure of grain-graincontacts responsible for the propagationof elasticwaves. Waves speed whose amplitude produce strain smallerthan 10 -6 wereobserved being independent of amplitude. Loss factors of granularmaterials also present identical variation withstrain. At largestrains (> 10 a) energyis mainlydissipated atgrain contacts, by dry friction in partialand gross slip forms. For low strains,energy is dissipatedby hysteresisinside the grainsthemselves. Applications of this techniqueto heavystructures are useful. 4:20 4pSA7, Experimentalstatistical energy analysis:A tool for the reductionof machinerynoise. N. Lalor (ISVR, Univ. of Southampton,Highfield, Southampton SO17 IBJ, UK) Theuse of statisticalenergy analysis (SEA) for thesolution of vibroacousticproblems that occur with the operation of machinery, hasonly recently become practicable. This paper charts the developments that led fromthe early ideas of energyaccountancy (EA) to thecurrent SEA modelingtechniques. The basicconcept of EA, whichwas conceived to showthe influenceof the overalldesign parameterson the radiatednoise, is explainedand its limitationsdiscussed. The paperthen goeson to describehow the various practicaldifficulties preventing the application of SEAwere overcome to thepoint where it couldbe usedas a practicaltool. Finally, a casehistory is presentedin whichan experimentalSEA modelis usedto determineinput (exciting) powers, power flow and sensitivityof thenoise to parameterchanges. lu addition,the use of an optimizationalgorithm for drivingthe noise level down to a targetspectrum within parameter and weightconstraints is alsodemonstrated. 4pSA8.Professor Richards after hissecond retirement. Joseph.M. Cuschieri(Dept. of OceanEng., Florida Atlantic Univ., Boca Raton, FL 33431) ProfessorRichards, or Prof, as he liked to be called,had just comeback from LoughboroughUniversity, where he wasthe Viee-Chaneellor.This was his second retirement. While searching for an appropriateresearch area, he identifiedmachinery noise as animportant issue. He formedthe machinery noise group in 1975,which I joinedin 1980.At thetime the group had seven members. Themain emphasis of the work was in theprediction and control of noisefrom impact machines--punch presses, drop hammers, etc. Profwanted to take a newlook at the parameters that control impact noise. A majorcontribution was the energy accountancy concept. Profwas a constantsource ofnew and fresh ideas, he would question any result or conclusion, andalways contributed new insight to theproblem and the results. Prof certainly had a uniqueapproach toget to the root of anissue. 1was fortunate that I keptin contact withProf after I cameto the US, as a freshPh.D., to join the faculty at Florida Atlantic University. His enthusiasm, inquisitiveness, andbroad experience were invaluable and had a significantinfluence on my career and I amsure that of others. 2568 J.Acoust. Soc. Am., Vol. 99, No. 4, Pt.2, April1996 131stMeeting: Acoustical Sociely of Arnedca 2568 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 THURSDAYAFTERNOON. 16 MAY 1996 REGENCYC AND D, 1:00TO 5:00P.M. Session4pSC Speech Communicationand Psychologicaland PhysiologicalAcoustics: Pediatric Cochlear Implants: RecentStudies of SpeechPerception and Production David B. Pisoni, Chair PsychologyDepartment, Speech Research Laboratory, Indiana University, Bloombtgton, Indiana 47405 Chair's Introduction--l:00 Invited Papers 1:05 4pSC1.Pediatric cochlear implantation: A review. RichardT. Miyamoto (Dept.of Otolaryngol.,Indiana Univ., Indianapolis, IN 46202) The fieldof pediatriccochlear implantation has changed tremendously since the early 1980s when single-channel cochlear implants werefirst provided to postlinguallydeafened children in the UnitedStates. Although implantation in childrenwas at firstrestricted to olderchildren with postlinguallyacquired hearing loss, it is nowcommon for prelinguallydeafened children as youngas two years of ageto receivea cochlearimplant. Furthermore, the introduction of multichannelcochlear implants and improved signal processing strategieshave resulted in far greaterspeech perception benefits than originally thought possible. This presentationwill reviewthe majordevelopments in pediatric implantation and summarize the results to date. [Work supported by NIDCD GrantNos. DC00064 and DC00423.] 1:30 4pSC2. Long-term performanceof prelinguisticallydeaf children usingthe Nucleus22 channelcochlear implant. StevenJ. Stallerand Anne L. Better (CochlearCorp., 61 InvernessDr. E., 200, Englewood,CO 80112} A sampleof 178 childrenhave been followed annually for the pastfive years,to assessthe developmentof speechperception abilitiesin earlydeafened children using a multichannelcochlear implant. A subsetof thesechildren who acquireddeafness prior to the acquisitionof language(prclinguistic) have shown continued improvement on a hierarchyof pediatricspeech perception tests throughoutthe follow-upperiod. Implantation at an early age appearsto improvethe prognosisfor developmentof moredifficult speechperception skills. In addition,there appears to be a positiverelationship between the emphasison oral listeningskills and the rate of acquisitionof speechperception abilities. Throughout the durationof the longitudinalstudy, several new speechprocessing strategieshave been introduced for theNucleus implant system. The mostrecent (SPEAK) is an adaptivestrategy that varies the rate of stimulationand the nmnberof electrodeis stimulatedaccording to the frequencycharacteristics of the speechsignal. SPEAK attemptsto representthe dynamic nature of speechand provides improved spectral detail by virtueof 22 closelyspaced electrodes. A sampleof 34 prelinguisticallydeafened children demonstrated significant improvements in speechperception within six monthsof conversionto the new processingstrategy. 1:55 4pSC3. Clinical investigationof the CLARION cochlear implant in children. Mary Joe Osberger,Sue Zimmerman-Phillips (Adv. BionicsCorp., 12740 San Fernando Rd., Sylmar,CA 91342),and Sigfrid Soli (HouseEar Inst.,Los Angeles, CA 90057) This presentationwill summarizethe designof the CLARION pediatricclinical trial andpresent initial findingson the subjects' performancewith the device. A repeatedmeasures design is usedto compare each subject's preoperativc performance with hearing aids to their postoperativeimplant performance on a batteryof outcomemeasures. Six categoriesof audiologicoutcome measures are administeredto the subjectsto achievestudy end pointsthat reflectthe rangeof benefitpredicted to occurin pediatricimplant users over time. Postoperativeevaluations with the CLARION are performedat 3, 6, and 12 monthsfollowing initial stimulation,and semiannuallythereafter. Initial findingscomparing subjects' preoperative performance to their 3-monthpostoperative performance with the CLARION reveal improvementson all speechperception outcome measures. Performance on the outcomemeasures, however,is confoundedby the limitedcognitive and linguistic skills of someof the subjects,especially in the youngest(2- and 3-year-old)children. Informalion will be presentedon issuesinherent in the designand implementationof a largemulticenter study of this nature. 2:20 4psc4. Open set speechrecognition in congenitally deaf children using a multichannel cnchlcar prosthesls, SusanWaltzman {Dept.of Otolaryngol.,NYU Schoolof Medicine,550 FirstAve., New York,NY 10016) Thirty-eightcongenitally deaf children received the Nucleusmultichannel cochlear prosthesis at NYU Medical Centerprior to age five. Preoperativeand postoperative evaluations included pure tone audiometry under earphones, warble tone audiometry in the sound field (amplificalionsystem preoperatively and implantpostoperatively), and open set measuresof word/sentencerecognition. Tests administeredincluded. but werenot limited to, GASP wordsand sentences, PBK words(scored as wordsand phonemes) and Indiana 2569 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April1996 131st Meeting:Acoustical Society of America 2569 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 phrasesand were administered preoperatively and6, 12,18, 24, 36, 48, and 60 monthspostoperatively. Results indicated a significant improvementover time in theability of thechildren to perceivewords and sentences in the implant only condition. Percent correct scoresimproved with length of usageand increasing age, reflecting increased ability of theyoung children to performthe necessary tasks,in additionto developingspeech recognition abilities. After using the device for two or moreyears the children had varying degreesof openset speech perception. These results demonstrate significant improvement in open set speech perception incongenitally deaf childrenimplanted below the age of five. 2:45 4pSC5.Lexical discrimination and age at implantation.Karen Iler Kirk (Dept.of Otolaryngol.,Indiana Univ., Indianapolis. IN 46202) Recentresearch suggests that prelingually deafened children implanted at an earlyage may obtain greater speech perception and languagebenefits than those children implanted at a laterage. This investigation examined word recognition and lexical discrimination in pediatriceochlear implant users as a functionof ageat implantation.Two groups of preliuguallydeafened children who used the Nucleusmultichannel cochlear implant participated in thisstudy. The firstgroup contained children who received their device between theages of 2-5 years,and the second contained children who were implanted between the ages of 6-9 years.Speech perception performancewas evaluated using a newmeasure, the Lexical lqeighborhood Test, a traditionalmeasure of wordrecognition, the PBK, anda measureof receptivelanguage abilities (the PPVT or theReynell Developmental Language Scales). Children implanted at a youngerage had better word recognition performance and were better able to identifylexically difficult words {i.e., those that occur infrequentlyand have many other phonemically similar words with which they can be confused). Correlations with vocabulary and languageperformance will alsobe reported. [Work supported by NIDCDDC00064.] 3:10-3:20 Break 3:20 4pSC6.Speech production and languagedevelopment in pediatriccochlear implant users. MarioA. Svirsky (Dept.of Otolaryngol.,Indiana Univ., Indianapolis,IN 46202) Cochlearimplantation has been very successfulin postlinguallydeafened children. Implants provide them with substantiallevels of speechreception, which in turnallows them to achievebetter intelligibility, speech production, and English language proficiency. Congenitallyor prelingua!lydeafened children, while less successful than the aforementioned group, have also shown benefit in speech productionand language measures. Performance varies greatly in thisgroup, but there appears to hea trendtowards better results when implantationis performedearlier in life. This presentationwill analyzemeasures of speechproduction and language ability in children deafenedbefore age 3 (whocomprise the vast majority of pediatriccochlear implant candidates) as well as in childrenwho are later deafened.Individual and group data will be discussedin viewof thesubjects' communication mode (oral or totalcommunication), age at deafening,age at implant,and yearsof experiencewith the implant.[Work supported by NIDCD GrantNos. DC00064and DC00423.] 3:45 4pSC7.Speech production and useof signby youngcochlear implant users. NancyTye-Murray (CentralInst. for the Deaf,909 S. Taylor,St. Louis,MO 63110),Linda Spencer (Univ. of IowaHospitals, Iowa City, IA 52242),and Brace Tomblin (Univ.of Iowa, Iowa City,IA 52242) The use of sign and the emergenceof speechskills by children who are deaf and use a cochleaximplant were examined. Twenty-fivechildren who had an averageof 43 monthsef experiencew.:th a Nuc4eu•cochlcar iraplant and who 0a'e•du•utcd in a simultaneouscommunication environment engaged in spontaneousconversation and completedspeech production and audiological tests.During spontaneousconversation, the childrenused voice and sign to expresswhole wordsin their conversations70% of the time, voiceonly 21%, and signonly 9% of the time, suggestingthat useof a cochlearimplant does not resultin eliminationof signing. Childrendemonstrated a wide rangeof intelligibility.Pearson correlations indicated that childrenwho had betterintelligibility were mostlikely to usevoice only, while childrenwho had poorinteiligibility were mostlikely to usesign only. Analysis of the children's consonantproduction over time suggestedthat fricative production emerges relatively early; but followsemergence of otherspeech skills,including the abilityto producenasal consonants. Measures of consonantproduction were significantly correlated with measures of consonantperception. This suggestsa closelink betweenchildren's ability to producespeech and perceivespeech. 4:10 4pSC8. Acoustic characteristicsof speech in French children using multichannel cochlear implants. Emily A. Tobey (UTD-Callier Ctr., 1966 Inwood Rd., Dallas, TX 75235), Alain Uziel, Martinc Sillon, Adrienne Vieu, and Francoise Artieres-Reuillard(Univ. of Montpellier,OR.L, Montpellier, France) Acousticcharacteristics of speech production produced with and without auditory feedback from a multichannelcochlear implant wasexamined in elevenFrench speaking children with profound hearing losses. Subjects produced five repetitions of stimulidesigned to contrastvoice-onset times and vowel ferment frequencies. Samples were collected with the implant turned on andafter a 10-rain periodof theimplant turned off. Stimuliwere audio recorded, low-pass filtered, and digitized at a 10-kHzrate. VOT's andferment 2570 J. Acoust.Soc. Am., Vol.99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2570 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 frequencieswere measured using Cspeech software. VeTs for thebilabial cognates, /b/ and/pLrevealed considerable overlap in temporalvalues when no auditoryfeedback was available. During conditions providing auditory feedback, VeTs shiftedto more nearlynormal values with minimal overlap. Vowel ferment frequencies also shifted as a functionof implantstatus; however, the patternsof shiftdiffered across subjects and across feedback conditions. Data suggest pediatric users of cochlearimplants are able to useauditory feedback toadjust their speech production; however, the relationships between auditory conditions and speech acoustics appearcomplex. [Work supported by theMinistere de la Santeand a visitingresearch scholar award from the University of Montpellier.] 4:35 4pSC9.Using electrically evoked auditory potentials in the clinicalmanagement of pediatriccochlear implant users. CarolynJ. Brown(Dept. of Otolaryngol.-Headand Neck Surgery, Univ. of IowaHospitals and Clinics, 200 Hawkins Dr., Iowa City, IA 52242) For manyyoung and/or prelingually deaf children, programming the speech processor of thecochlear implant and identifying malfunctioningelectrodes or internaldevice failures can be difficult. Electrophysiologic recording techniques can be used to address bothissues. The electricallyevoked auditory brain-stem response (EABR) can be usedto assistin deviceprogramming. Data describingthe relationship between EABR threshold and behavioral measures of threshold and maximum comfort level for a groupof 26 Nucleuscochlear implant users will be reviewed.Electrophysiologic techniques can also be usedto recordthe stimulus artifact associatedwith activation of theNucleus device. This response has been called the average electrode voltage (AEV) andhas proven to beuseful in identifyingcases where there is totalfailure of theinternal components of the Nucleus cochlear implant as well as diagnosingmalfunction of individual electrodes. Normatire data collected using three different stimulation modes from a groupof 20 Nucleuscochlear implant users will be presented.,Examples of commonlyobserved abnormal AEV recordingswill be describedand comparedwith AEVs recorded using an internal Nucleus electrode array submerged in a salinetank. [Work supported by NIH andthe Iowa LionsFoundation.] THURSDAY AFTERNOON, 16 MAY 1996 CELEBRATION B, 1:30 TO 4:20 RM. Session4pUW Underwater Acoustics:Signal Processingand General Topics William M. Carey, Chair DARPA/MSTO,3701 North Fairfax Drive, Arlington,Virginia 22203 Chair's Introduction--1:30 ContributedPapers 1:35 andchannel parameters [D. F. Gingrasand P. Getsoft, J. Acoust.Soc. Am. 97, 3589-3598 (1995)],these strategies require higher signal-to-noise ra- 4pUWl, Active matched-field tracking, Homer Bucker and Paul tios.The methodspresented here concern the designof robustnonadaptive Baxley (Code541, RDTE Div. NCCOSC,San Diego, CA 92106) beamformerweights with sidelobelevels which are less signal-to-noise The principaltask of a sonarsystem is Io generatepossible tracks of an ratio dependent.As with Chebysbevfilters, the weightsare designedto acousticsource. Matehed-field tracking [Bucker, J. Acoust.Sec. Am. 96, minimizethe maximummagnitude-squared sidelobe level. Robustnessto 3809-3811(1994)] is a signalprocessing algorithm for thispurpose that hasminimum operator input. In thispresentation, the methodis appliedto magnitude-squaredresponse averaged over an ensembleof environmental activesonar systems by extendingthe definitionof coverlancematrix el- conditions.The two algorithmsproposed are a fast iterativeconstrained ements.A samplesimulation will be shownwhere operator-independent minimumvariance method and the useof a minimaxquadratic program- tracks are obtained at different noise levels. mingtechnique. For an uncertainMediterranean environment, an improve- ment in the maximumaverage sidelobe level of as muchas 3 dB over the Bartlettbeamformer is achieved.[Work supported by NRaD/ONR.] 1:50 environmentalmismatchisachievedbydefining thesidelobelevel asthe 2:05 4pUW2. Robust nonadaptive matched-field beamforming in an uncertain oceanenvironment. Kerem Harmanciand Jeffrey L. Krolik 4pUW3. The determination of optimum array lengths based on (Dept.of Elec.and Cornput. Eng., Duke Univ., Box 90291,Durham, NC signal coherencein deep and shallow water, William M. Carey 27708-0291) (ARPA,3701 N. FairfaxDr., Arlington.VA 22203)and Peter Cable (BBN Systemsand Technol.,1300 N. 17th St., Arlington,VA 222091 Matched-fieldprocessing techniques can be bothambiguity-prone and sensitiveto errors in the assumedenvironmental conditions. A]tbough Experimentalmeasurements of signalcoherence and array signal gain grealerrobustness to environmentalvariability can be obtainedby the use are reviewedfor bothdeep and shallowwater sound channels. The signal of dataadaptive methods, such as the MV-EPCbeamformer [J. L. Krolik, gain is relatedto singlepath or modal coherencelengths through well- J. Acoust.Soc. Am. 92, 1408-1419 (1992)] or joint estimationof source knownrelationships in the statisticaltheory of antennas.Signal gain men- 2571 d. Acoust.Soc. Am., VoL 99, No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society of America 2571 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 surementsin the transverseand longitudinal directions are proffered as the 2:50-3:05 Break optimummeasures of coherencelengths for bothbroadband and narrow- bandsignals. Using this technique measerements (< 1 kHz) arepresented thatshow for thedeep water cases lengths on theorder of 300 wavelengths can be achieved while in the downward refraction conditions of a shallow water waveguidelengths between 30 and 100 wavelengthsare realized. 3:05 The measurement of broadband and narrow-band coherence and correla- tion functionsare discussedwith emphasison the role of partlycoherent 4pUW6. Travel time variability and localization accuracy for global noisebackgrounds and multipathinterference effects as well as averaging scalemonitoring of underwateracoustic events. Ted Farrell (BBN constraints.These results are interpretedwith coherencemodels based on Systemsand Technologies, 1300 N. 17thSt., Arlington,VA 22209)and soundscattering from the volumeand boundariesof the waveguide.The KevinD. LePage (BBNAcoustic Technologies, Cambridge, MA 02138) requirementsfor the numericalmodeling of the signalcoherence are pre- sented. Large amplitudeunderwater acoustic signals, such as thoseproduced by earthquakesand nuclear tests, can be monitoredon a globalscale using a limited network of underwateracoustic sensors. The designand opera- tion of sucha networkrequires an understandingof the limitson localiza- 2:20 tionaccuracy due to soundspeed fluctuations in theocean. For localization basedon time of flight, the varianceof the arrivaltime of the individual 4pUW4. Conjugate mirror array performance in the presenceof modesmay be estimatcdby a rangeand depthintegral over the sound- surface and bottom roughness. Terry E. Ewart, Daniel Rouseif, and speedfluctuation statistics of the watercolumn. Results obtained for travel Darrell Jackson (Appl. Phys.Lab. and Schoolof Oceanogr.,Univ. of Washington,Seattle, WA 98105) time varianceusing this approachare comparedto simplermeasures such asthe variance of thesound axis slowness integraled over a geodesicpath. Dowlingand Jackson [J. Acoust.Soc. Am. 91, 3257-3277 (1992)] These results are in turn utilized to estimate the localization areas of un- provideda studyof the temporal/spatialeffects of an internalwave field on certaintyfor a variety of sourceand receiver scenarios.All resultsare phaseconjugate arrays. In the presentwork the effectsof interfacerough- basedon measuredsound-speed statistics obtained from various ocean nesson phaseconjugate arrays are simulated.The stochasticsurface wave databases.[Work supported by DOE andAir ForcePhillips Laboratory.] field is generatedto includerealizations of the sea surfaceheight that evolvein time. The time variabilityof the surfacealso includes the effects of the acoustic travel time, so that each realization is "as viewed" in the frame of the acousticwave from source-array-to-recciving-arrayand the returnafter phase conjugation., The acousticwave propagationis accom- 3:20 plishedusing a parabolicequation marching algorithm that includesthis randomrough surface.Bottom penetrationand absorptionare included. 4pUW7. An empirical fractal model for corona dischargesin salt Couplingof the surfacewave field with the bottom/sub-bottomrandom- water, J.C. Espinosa,H. M. Jones,A.M. Gleeson, and P,. L. Rogers nesscan produce an increaseddegradation of the returnfield. Thus even if (Appl.Res. Labs., Univ. of Texas,P.O. Box 8029, Austin, TX 78713-8029) the processingtime to producethe conjugatefield approachedzero, deg- radationof the conjugatearray focuswill occur.A discussionof the rel- A coronadischarge in water and a concomitantacoustic pulse is pro- evance of this work to conjugatearray applicationswill be presented. [Worksupported by ONR.] ducedwhen a highelectric field is appliedacross a pair of electrodes.The coronastructure consists of manybranching plasma fingers. The acoustic signalis producedby the formationand collapseof a vaporbubble; how- ever, the detailsof this processare unclear.Furthermore, the relationbe- tween the acousticand fraetel stagesis unknown.Voltage and current 2:35 waveforms,obtained previously, are accuratelydescribed by a fractal 4pUW5. Model-based processingof broadband sources in noisy model.High-speed photographs of dischargeshave been taken to further shallow oceanenvironments. JamesV. Candy (LawrenceLivermore investigatethe natureof coronadischarges and elucidate the relationship Natl. Lab., Univ. of California, P.O. Box 808, L-495, Livermore, CA betweenthe •vo stages.From theseexperiments, an empirical model is 94550)and Edmund J. Sullivan (NavalUndersea Warfare Ctr., Newport, underdevelopment that incorporatesboth the fraeteland acousticaspects RI 02841) of corona discharges.The most recent resultsof this effort will be pre- sented.[Work supported by the Officeof Naval Research.] Broadbandacoustic sources propagating in a hostile (noisy) ocean complicatethe analysisof received acousticdata considerably.Normal- modemodels are reasonablepropagators for usein a shallowocean envi- ronments.Our previouswork developedthe Gauss-Markovrepresentation of the narrow-bandnormal-mode model and then recentlyextended it to 3:35 thebroadband case [Candy and Sullivan, J. Acoust.Soc. Am. Suppl.I 98. (1995)].In thispaper the design and trade-offs of theprocessor are inves- 4pUW8. Cylindrical bubble evolution and acoustic signature tigatedwhen applied to bothsynthesized and experimental data in orderto through the arc phase of an electrical discharge. David L. Fisher constructthe desiredbroadband processor. The enhancementof broadband andRobert L. Rogers (Appl.Res. Labs., Univ. of Texasat Austin,Austin, acousticpressure-field measurements along with the estimationof under- TX 71713-8029) lyingmodel functions using a verticalm-ray is discussed.The model-based approachis developedand implementedfor a broadbandsource using a The are phaseof an electricaldischarge in salt wateris investigated normalmode propagation model. The structureof the processoris of in- usinga l-D nonlinearfluid modelin cylindrical(r) coordinates.For most terest,since it has an implied parallelstructure due to the propagation physics,while the optimalestimation solution implies a "full" structure. electrodegeometries, the arc phaseis moreaccurately modeled using a The apparentdiscrepancy is resolvedand the processoris implemented cylindricalgeometry compared to the usualand simplerto implement usinga "bank" of narrow-bandmodel-based processors. The resulting sphericalmodel. This is due to the fact that until the bubble radius is broadbandpressure-field estimates are quitereasonable for bothsynthe- comparableto thedistance between electrodes, the preferred geometry is sizedand experimental data. cylindrical.Both the bubblesexternal (water) and internal(dissociated 2572 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, Apdl1996 131stMeeting: Acoustical Society of Arnedca 2572 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 waterand plasma) are discretized and modeled with nonlinearfluid equa- the thermalfluctuations. Results from preliminaryacoustic tests will be tions.The model includesthe energy flow from the capacitor,into the discussed.[Work supported by theOffice of NavalResearch and the Ap- plasmaare throughits resistivity,and then finally into the hydroacoustic pliedResearch Laboratory.] pulse.Simulation results will be comparedto experiments.Also the effi- ciencyof variouselectrode configurations will be investigated.[Work sup- 4:05 portedby theOffice of NavalResearch.] 4pUWI0. Observationof low-frequencywave generationin a bubble layer. AlexanderM. Sutin, Irina A. Soustara,Alexander I. Matveyev, AndreyI. Potapov (Inst.of Appl.Phys., Russian Aced. Sci., 46 Ulyanov str.,Nizhny Novgorod, 603600, Russia), and Lev. A. Ostrovsky(Inst. of 3:50 Appl. Phys. and Univ. of Colorado, CIRES/NOAA Environmental Technol.Lab., Boulder,CO 80303) 4pUW9. Underwater turbulence injection system for investigationof acousticpropagation in a randomly fluctuating medium. Barry J. The difference-frequencysound generation as a resultof theinteraction Doust,Kenneth E. Gilbert,and RalphR. Goodman (Appi. Res.Lab. and of two high-frequencyharmonic waves in a bubble layer in water are the GraduateProgram in Acoust., Penn State Univ., P.O. Box 30, State investigatedexperimentally and theoretically.As it was shownbefore, the College,PA 16804) use of the layer resonancecan increasethe efficiencyof the nonlinear transformationof the signal.Here the dataof the experimentwith a bubble A preliminaryinvestigation using cold water from meltingice to in- layerof the thicknessof about10 cm in the anechoictank are presented. ducesound-speed fluctuations has shownsignificant effects on both one- One of the incident(primary) wave frequencieswas 60 kHz while the way and two-way propagation.Although the melting ice approachis anothervaried from 59 to 50 kHz, thusproviding the low-frequencysignal simpleand effective, il is noteasily controlled. The purposeof thepresent in the rangeof I to 10 kHz. Due to the first-modelayer resonance,this researchis to developa methodfor generatingcontrolled sound-speed secondarysignal had a pronouncedmaximum at the frequencyof 2.2 kHz fluctuationsby creatinga thermalfield with stableand repeatable statistics. (whilethe primarywave was in resonancewith the bubblesof the radius The work has led to a novelcold water injectionsystem for generating about45 /xm, and no resonancein the layer was observedfor it). The thermalfluctuations in anexperimental tank. A relativelysimple device has bubblevolume ratio from theseexperiments was estimatedto be about beendesigned for producinga rangeof turbulencespectra by varyingthe 1.4x10 -n. A theorywas also developed for this type of interactionwhich flow tale and orificesizes. This paperwill focuson the characteristicsof describedwell the experimemal results. [Work was supported by theRus- the cold waterinjection system and will discussits advantagesover sys- sian Foundation of Fundamental Research Grant No. N0-93-05-8074 and temsthat use, for example,electric heaters or hot waterinjection to create by the ScienceOpportunity Program of the Officeof Naval Research.] THURSDAY AFTERNOON, 16 MAY 1996 NATIONAL PARKS, 1:30 TO 2:45 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,1EC/TC 29 Electroacoustics, and ISO/TC 108/SC4 Human Exposure to Mechanical Vibration and Shock T. A. Frank, Chair $3 PennsylvaniaState University,Speech and Hearing Clinic, 110 Moore Building, UniversityPark, Pennsylvania16802 R. E Burkhard, Vice Chair S3 Hearing ResearchLaboratoriy, State Universityof New Yorkat Buffalo, 215 Parker Hall, Buffalo,New York 14214 P. D. Schomer,Chair, U. S. TechnicalAdvisory Group (TAG) for ISO/TC 43, Acoustics U.S. CER[• PO. Box 4005, Champaign,Illinois 61820 H. E. van Gierke,Vice Chair,U. $. TechnicalAdvisory Group (TAG) for ISO/TC 43, Acousticsand ISO/TC I08/SC4, HumanExposure to MechanicalVibration and Shock 1325 Meadow Lane, YellowSprings, Ohio 45387 V. Nedzelnitsky,U.S. TechnicalAdvisor (TA) for IEC/TC 29, Electroacoustics NationalInstitute of Standardsand Technology(NIST), Building233, RoomA149, Gaithersburg,Maryland 20899 StandardsCommittee S3 on Bioacoustics.The currentstatus of standardsunder preparation will be discussed.In additionto those topicsof interest,including hearing conservation, noise, dosimco:rs, hearing aids, etc., consideration will be givento newstandards whichmight be neededover the next few years.Open discussion of committeereports is encouraged.The internationalactivities in ISO/TC 43 Acoustics,and IEC/TC 29 Electroacoustics,and ISO/TC 108/SC4Human Exposure to MechanicalVibration and Shock, 2573 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society of America 2573 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 will alsobe discussed.The Chairsof the U.S. TechnicalAdvisory Groups for ISO/TC43 (P.D.Schomer), IECdTC 29 (V. Ned- zelnitsky),andISO/TC 108/SC4 (H. E. yon Gierke) will report on current activities ofthese international Technical Committees and Subcommittees,including the meetingsof ISO/TC 43 andIEC/TC 29 heldin Pretoria,South Africa, in February1996. Scopeof S3. Standards,specifications, methods of measurementand test, and terminologyin the fields of mechanicalshock and physiologicalacoustics, including aspects of generalacoustics, shock, and vibration which pertain to biologicalsafety, tolorance, and comfort. THURSDAY AFTERNOON, 16 MAY 1996 NATIONAL PARKS, 3:00 TO 5:00 P.M Meeting of AccreditedStandards Committee S1 on Acoustics to be heldjointly with the U.S. TechnicalAdvisory Group for ISO/TC 43 Acousticsand IEC/TC 29 Electroacoustics G. S. K. Wong, Chair S1 Institutefor National MeasurementStandards (INMS), National ResearchCouncil, Ottawa, Ontario K1A OR6,Canada R. W. Krug, Vice Chair S1 Cirrus Research, Inc., 6423 West North Avenue, Suite 170, Wauwatosa, Wisconsin 53213 P. D. Schomer,Chair, U.S. TechnicalAdvisory Group (TAG) for ISOfrC 43, Acoustics U.S. CERL, P.O. Box 4005, Champaign,Illinois 61820 H. E. vonGierke, Vice Chair,U.S. TechnicalAdvisory Group (TAG) for Isofrc 43, Acoustics 1325 MeadowLane, YellowSprings, Ohio 45387 V. Nedzelnitsky,U.S. TechnicalAdvisor (TA) for IEC/TC 29, Electroacoustics National Instituteof Standardsand Technology(NIST), Building233, RoomA149, Gaithersburg,Maryland 20899 StandardsCommittee S1 on Acoustics.Working group chairs will reporton theirpreparation of standardson methodsof measure- mentand testing. and terminology, in physicalacoustics. electroacoustics, sorties, ultrasorties. and underwater sound. Work in progress includesmeasurement of noisesources, noise dosimeters, integrating sound-level meters, and revisionand extensionof soundlevel meterspecifications. Open discussion of committeereports is encouraged.The internationalactivities in ISO/TC 43 Acoustics,and IEC/TC 29 Electroacoustics,will alsobe discussed.The chairsof therespective U.S. TechnicalAdvisory Groups for ISO/TC 43 (ED. Schomer)and IEC/TC 29 (V. Nedzelnitsky)will reporton current activities of theseinternational Technical Committees, including the meetingsof ISO/TC 43 andIEC/TC 29 heldin Pretoria.South Africa, in February1996. Scopeof S1. Standards,specifications, methods of measurement,and test and terminology in the fieldof physicalacoustics including architecturalacoustics, electroacoustics. sonics and ulwasonics, and underwater sound, but excludingthose aspects which pertain to biological safety,tolerance and comfort. 2574 J. Acoust.Soc. Am., Vol. 99, No.4, Pt.2, Apdl1996 131stMeeting: Acoustical Society of America 2574 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, 17 MAY 1996 NATIONAL PARKS, 8:00 TO 11:30 A.M. Session 5aAB Animal Bioacoustics: Effects of Noise on Animals Larry L. Pater,Chair USA-CERL,P.O. Box 9005, 2902 NewmarkDrive, Champaign,Illi•tois 61826-9005 Chair's Introduction4:00 Invited Papers 8:05 5aABI. The effect of roadway traffic noiseon territory selectionby Golden-cheekedWarblers. RobertH. Benson (Ctr. for Bioacoustics,Texas A&M Univ., CollegeStation, TX 77843-3367) Widespreadconcern that environmentalnoise produced by humanscan negativelyaffect animal populations is reflectedin a growingbody of literature.This study evaluates the possible effects of roadwaytraffic noise on territoryselection by theendangered Golden-cheekedWarbler. Sevenly-eight listening posts were establishedrandomly in a 212 ha studyarea in centralTexas. Noise exposureat eachpost was estimated using a noisesimulation model based on trafficcounts. The presenceor absenceof warblersat eachpost was determined by fieldobservations. Data wereanalyzed to determineif a correlationexisted belween the estimated noise exposureand the occurrence of warblers ata listeningpost. Exposure in Leq{h ) ranged from 29.7-58.6 dB. Warblers were detected at 30 of the78 listeningposts. When the 78 postswere divided into high-noise and low-noise groups, there was no significantdifference betweenthe occurrence of warblersin thegroups. Logistic regression failed to reveala significantcorrelation between the occurrence of warblersat listeningposts and the exposureto noise.It is concludedthat, within the rangeof noiseexposures considered in this study,Golden-cheeked Warblers do not selectterritories based on exposureto roadwaytraffic noise. 8:25 5nAB2.USAF monitorsfor recordingaircraft noisereceived by animals. MichaelCarter (ArmstrongLab., Wright-Patterson AFB, OH 45433)and Robert Kull (ArmstrongLab., Brooks AFB, TX 78235) Althoughre,archers havestudied the effectsof airemil noiseon wild anddomestic animals for manyyears, accurate descriptions of the noiselevels received by the animalsin manyof the studieswas not verified.Recent technology has allowed for the miniatur- izationof muchof thehardware for noisemonitoring devices, making it feasibleto builda noisemonitor small enough to fit on a large animalcollar. An animalnoise monitor (ANM) wasdesigned and built to captureA- andC-weighted noise levels above a program- mablethreshold, distinguishing aircraft noise from othersound sources. The device,weighing only 350 g, alsocaptures onset rate, Leq, and grossmovements of the animalvia accelerometersafter a noiseevent, while fittingon a largeanimal collar. The ANMs were also designedto functionas stand-alone,weatherproof units for up to 6 months.The ANMs havealready been field testedunder natural weatherconditions at stationarylocations by PeregrineFalcon aeries around Fairbanks, Alaska. The ANMs will be testedon penned animalsto determinetheir reliabilityand accuracy. 8:45 5aAB3. Performance of desert kit foxes, Vulpes mawrotisarsipus, on acoustic detection trials during simulated jet aircraft overflights. Ann E. Bowles,Scott Yaeger (Hubbs-SeaWorld Res. Inst., 2595 IngralnamSt., SanDiego, CA 92109),B. Andrew Kugler (BBN Systemsand Technologies Corp., Canoga Park, CA 91303),and Richard Golightly (HumboldtState Univ., Arcata, CA) Two maleand femaledesert kit foxeswere exposedto simulatedprey and predatorsounds in the presenceof aircraftnoise to determinedetection rates. They were testedin a 9.75X 9.15-m outdoorpen in the dark. Five feedingstations were equippedwith speakersto playscratching sounds (prey noise) and a singlespeaker outside the pen projected stealthy footsteps (predator noise). Foxes approachedfeeding stations projecting prey noiseto receivea reward;they spontaneouslyavoided predator noise. Foxes were exposedto980 simulatedlow-altitude jet overflightsin therange from 65 to 95 dB ASEL. Stimulussounds were played for I min at thelimit of detection;the longestsimulated overflight was 45 s. Fox performancewas compared with andwithout simulated aircraft 2575 d. Acoust.Soc. Am., VoL 99, No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society of America 2575 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 noise(309 and 110trials, respectively). Foxes exhibited flight reactions or droppedflat duringinitial exposures. Within 1-2 seriesof exposures,these responses habituated, although milder reactions persisted. Foxes identified the correctfeeding station 63%-71% of the time (chancerate=20%) in silenceversus 24%-30% in noise.They detectedpredator sounds on 81%-83% of trials,regardless of noise.The results suggest that foxes listened for potentialpredaters preferentially in thepresence of aircraftnoise. [Work supported by USAFNSBIT Program, Contract F33615-90-D-0653.] 9:05 SAAB4. Effects of underwater sound on hair cells of the inner ear and lateral line of the oscar (Aslronot•s oce!!at•s). MardiC. Hastings(Dept. of Mech.Eng., Ohio State Univ., 206 W. 18thAve., Columbus, OH 43210),Arthur N. Popper (Univ.of Maryland,College Park, MD 20742),James J. Firmerart(Ohio State Univ., Columbus, OH 43210),and Pamela J. Lanford(Univ. of Maryland,College Park, MD 20742) Fifty-nineoscars (AstrahOrUS ocellatus) were subjected to puretones at 60 or 300 Hz in orderto determinethe effects of soundat levelstypical of rnan-madesources on the sensoryepithelia of theear and the lateralline. Sounds varied in dutycycle (20% or continuous)and sound-pressure level (100, 140, or 180 dB re: I /zPa).Fish wereallowed to survivefor oneor four dayspost- treatment.The studyalso included five controlanimals that were handled in thesame way as the testanimals, but werenot exposed to any sound.Tissue was then evaluated using scanning electron microscopy to assessthe presenceor absenceof ciliarybundles on the sensoryhair cellsin eachof the oticendorgans and the lateralline. Damagewas found in fourof five fishstimulated with 300-Hz continuoustones at 180 dB and allowedto survivefor four days.It waslimited to smallregions of the striolaof the utricleand lagena. No damagewas observedin fish that had beenallowed to survivefor one day post-stimulation,suggesting that physicalsigns of damagemay develop slowly after exposure. [Work supported by ONR.] 9:25 $aABS. The impact of impulsive noise on bald eaglesat Aberdeen Proving Ground, Maryland. William A. Russell,Jr., NelsonD. Lewis (Environ.Noise Program, U.S. Army Ctr. for HealthPromotion and Preventive Medicine, ATTN: MCHB-DP-B, AberdeenProving Ground, MD 21010-5422),and Bryan T. Brown (SWCA, Inc. Environ.Consultants, Flagstaff, AZ 86001) The U.S. Army AberdeenProving Ground supports one of the largestbald eagle concentrations on the NorthernChesapeake Bay (Buehleret al., 1987).The testing of largecaliber weapons and detonation of largeexplosive charges at U.S.Army Aberdeen Proving Groundis creatingsignificant noise and producing concerns on the potentialeffects on bald eagles.The populationusing Aberdeen consistsof approximately15 nestingpairs and up to 100 winteringor nonbreedingresidents. Systematic observations on potential influenceof noiseon bald eagleswere madefrom November1993 throughDecember 1995. We detectedno responsein a high percentageof nestingand roosting eagles exposed to numeroustypes of noiseat varyinglevels of intensity. 9:45 5aAB6. Discussionand demonstrationof PC CITASAN. Paul A. Sharp (2610 SeventhSt., Wright PattersonAFB, OH 45433-7901) PC CITASANis a softwareprogram that contains a databaseof over4500 references to scientificliterature on theimpact of aircraft noiseand sonic booms on humans,animals, structures, and noise modeling. It containsbibliographic data and a suitabilityrating and a controversialityrating for eacharticle. Some articles also have an abstractand an independentreview. The datawere updated as of Nov 1994.The PC C1TASANdatabase can be searchedusing four differentpre-defined screens, one for eachimpact category. The searchcan be global,by author,by key wordsin the title, or by yearof publication.The programwas developed for useby USAF personnelpreparing environmental assessment documents. However, it hasbroad application to othergovernment, civilian, academic, andconunereial organizations. The programwas originally written to operateunder the UNIX operatingsystem using ORACLE as the database.It has beencompletely re-written to mn underthe Windowsenvironment on a PC as a standalone system and doesnot requirea dedicateddatabase. It will be distributedon a CD-ROM with a hardcopyuser's manual. 10:05-10:20 Break 10:20 SAAB7.Field methodsfor measuring auditory function in wild animals. Ann E. Bowles (Hubbs-SeaWorld Res. Inst., 2595 IngrahamSt., San Diego, CA 92109) Laboratorycharacterization of auditorysensitivity in wild vertebratesis typicallybased on measurementsfrom a smallnumber of relativelyhealthy and young individuals. The auditory sensitivities of animalsin populations are likely to varygreatly; individuals will varyin sensitivityat birth,and will experiencediminished capacity due to injuries,noise exposure, age, starvation, reproductive stresses,parasites, etc. Although disabilities might be fatalfor bearing-dependentspecies, such as nocturnal animals, healthy indi- vidualswith profoundloss are sometimesfound. Hypotheses about the adaptivevalue of hearingcannot be addressedwithout 2576 d.Acoust. Soc. Am., Vol. 99, No. 4, Pt.2, Apdl1996 131stMeeting: Acoustical Society of America 2576 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 techniquesto measureanimal hearing quickly and accurately in field situations.While conditioning("behavioral") studies are the "goldstandard" against which other techniques are evaluated, they cannot be usedeasily in the field.Examples of othertechniques will be givenand comparedwith behavioralmeasures for the sameor similarspecies. These are (1) reflexmodification (startle inhibition)used on 4 kit foxes(Vulpes macrods) and 4 Merriam'skangaroo rats (Dipodomysmerriami), (2) auditorybrain-stem responsesused on 16kangaroo rats and 12 desert tortoises (Gopherus agassizii), and (3) envelope-followingresponses used on a desert tortoiseand a harborseal (Phoca vitulina). 10:40 5aAB8.Response of nonbreedingspotted owls to helicopterand chain saw noise. TerylG. Grubb,David K. Delaney(Rocky MountainForest and Range Experiment Station, USDA Forest Service, Flagstaff, AZ), M. HildegardReiser (HollomanAir Force Base,NM), PaulBeier (NorthernArizona Univ., Flagstaff, AZ), andLarry L. Pater (U.S. ArmyConstruction Eng. Res. Labs., Champaign,IL) Mexicanspotted owls (Strix occidentalis lucida) were exposed to two typesof noisystimuli: very low altitudehelicopter overflightsand chain saw activity. The stimuli were presented to the owls at severaldistances and noise levels during daylight hours in Julythrough September 1995. Responses were characterized into two categories, "alert" and "flight." "Alert" responses to low altitudehelicopter overflights were typical, but "flight"responses occurred for onlya smallpercentage of the trials.Chain saw presentationsat similar distances elicited "flight" responses much more frequently. Consideration was given during data analysis to theowls' hearing range and sensitivity. [Research supported by U.S.Air Force.] ContributedPapers 11:00 11:15 5aAB9. Sensitization and habituation to underwater sound by 5aAB10, Effects of sound and ultrasound on Zebra Mussels. Dimitri captivepinnipeds. David Kastak and Ronald J. Schusterman(Long M. Donskoy (DavidsonLab., StevensInst. of Technol.,Hoboken, NJ Marine Lab., Univ. of California,Santa Cruz, CA 95060) 07030),Michael Ludyanskiy (LONZA, Inc., Annandale, NJ 08801),and DavidA. Wright (Univ.of Maryland,Solomons, MD 20688) Responsivenessof three species of pinnipedto twotypes of brief(5-s duration)underwater sound was investigated.The experimentalstimulus The freshwater bivalve mollusk, Dreissena polymorpha - better wasa broadbandpulsed sound (peak levels of 110-135dB re: I /xPa).The known as the Zebra Mussel, since its introductioninto the Great Lakes in controlstimulus was a frequencysweep (rms level of 125-130dB re: l 1985has been quickly spreading throughout the waterwaysof boththe btPa).Reactions were classified as avoidanceor approach.Two California United Statesand Canadacausing serious economic and environmental sea lions and a harbor seal showed no avoidance reaction to either stimu- consequences.The presentstudy has been directed toward developing lus.A northernelephant seal showed a powerfulavoidance response to the acoustictechniques to controlZebra Mussel infestation in variouswater pulsedsound and showed little reaction to thefrequency sweep. The sea intakeand storage facilities. The effects of ultrasonicand hydrodynamic lionsand harbor seal clearly showed habituation to bothsounds. However, cavitation,low-frequency sound and vibration on variouslife stagemus- ratherthan showing habituation, the elephant seal showed sensitization to sels(from eggs and larvae to adults)have been studied. It wasfound that cavitationcan be usedas a controlmeasure for ZebraMussel veligers. The theexperimental stimulus, as well as to theentire experimental setup. That efficiencyof the ultrasonicand hydrodynamic cavitation treatments were is, as the experimentprogressed, avoidance response to the signalwas measuredas an outputenergy rate to achieve100% mortality. Laboratory fasterand duration of post-stimulushaulout behavior increased. In fact, experimentsdemonstrated the effective use of low-frequencywaterborne followingsuccessive presentations of the pulsedsound, it wasoften not soundto preventZebra Mussels from settlingand translocating and to possibleto coaxthe elephant seal back into the water. The results suggest reducereproduction abilities of mussels.[This work has been supported by thatthere are species-specific constraints on habituation to certaintypes of Grant No. NA26RG0403-01 from the NOAA to the Stevens Institute of environmental stimuli. Technology,New Jersey Sea Grant College Program.] 2577 d.Acoust. Soc. Am., Vol. 99, No.4, Pt.2, April1996 131stMeeting: Acoustical Society of America 2577 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, 17 MAY 1996 CELEBRATION B, 8:30 TO 9:45 A.M. Session SaNS Noise: Topicsin Community Noise and Noise Control Gerald C. Lauchle, Chair Graduate Program in Acoustics,Applied ResearchLaborato .ry,Pennsylvania State Universit3;P.O. Box 30, State College, Pennsylvania16804 ContributedPapers 8:30 pumpvane or pistonpassage frequency. In thisstudy, the effectivenessof in-linetuning cables (after a patentby Klees 1967) for quietingthe har- 5aNSI. Problem areas in predicting community noise that affect monic noise from thesehydraulic lines is determined.This approach, accuracy. FrankH. Brittain (BechtelCorp., 50 BealeSt., SanFrancisco, whichcombines ease of installationwith relativeeconomy. amounts to the CA 94105) insertionof a quarter-wavelengthside branchinto the acousticalcircuit. In theory,predicting community noise levels is relativelyeasy -- once Crilical to effectivedesign is the determinationof the wave speedsin the the neededinformation can be found. While the equationsneeded to for- flexible hosing.Theoretical predictions and measurementsare appliedto mulatea noiseprediction model are in theliterature, unfortunately, they are determinethe wave speedsin the fluid-loadedhydraulic line. Multiple spreadbetween many references. Adequate information on noiselevels of PVDF sensorsmeasure wave speedsand the wave amplitudeinsertion loss sources-- either as sound-pressureor power levels-- is often not avail- achievedby the device.Experiments performed on a full-scale60 h.p., able in the literature.Further, transmission loss data at low frequenciesare 1500 p.s.i. unit will be comparedto the theory. Soundpressure levels notusually available. When one gets around these problems, another set of determinedesign effectiveness. problemsarises that is relatedto the accuracyof the modelsdeveloped. Theseproblems include source size and directivity,barrier and screening effectsof equipment,reflections by equipmentand buildings,piping and minor equipment,atmospheric and groundeffects, and effectivenessof noisecontrol barriers. Typical prediction technology is summarized.Prob- 9:15 lem areasthat affect accuracyof noisepredictions are identifiedand dis- SANS4.A study of noise reduction by antisound using bypass in cussed. ducts with flow. Zhichi Zhu, Rui Guo (Dept. of Eng. Mechanics, TsinghuaUniv., Beijing, 100084,People's Republic of China),and Rui 8:45 Tien (InnerMongolia Polytechnic Univ., Huhhot, People's Republic of China) 5aNS2. Relationshipbetween judgments of neighborhoodnoisiness and prevalenceof annoyance. SanfordA. Fidell and Laura A. Silvati Noisereduction in ductswith flow is a very usefulproject. With com- (AcousticTechnologies Div., BBN Corp.,21120 VanowenSt., Canoga monantisound methods, electronic instruments are required, so its appli- Park, CA 91303-2853) cation is restricted.By usingbypass added to the main duct with flow, downstreamnoise reduction can also be obtainedif suitablebypass param- Dosage-responsefunctions that relatethe time-weighteddaily average etersare selected:This simplemethod is completelyin accordwith anti- soundpower of outdoornoise to the prevalenceof a consequentialdegree soundprinciple. But soundfield analysis in thiscase is quitea complicated of noise-inducedannoyance in communitiesare often viewed as providing problem.The numericaland experimentalresearch was completed by the a basisfor land usecompatibility policy recommendalions.Although such authors.The numericalwork includedformulating acoustic relations and functionsadvance understanding of the rate of growthof annoyancewith joint conditionsand calculatingthe transmissionloss for various noise soundlevel andof relatedmatters, they do not in themselvesdictate any sources.The experimentalresearch on a ductwith singlebypass and outlet particularpolicy recommendations.It is thereforeuseful to considerhow absorbingwedge underthe conditionsof differentnoise sourcesand flow the growthof noise-inducedannoyance is itself relatedto othernonacous- velocities was carried out in a national lab. The measured data were in tic measuresof communityresponse to noiseexposure, such as the rateof good agreementwith the numericalresults and considerablenoise reduc- growthof neighborhoodnoisiness judgments with soundlevel. A proba- tionwas obtained in bothdB(A) and !13octave band. Finally, a spottest bilistic model of communityresponse to noiseexposure developed by of noisereduction using double bypasses was carded out. It was shown Greenand Fidell (1991)is shownto providea goodaccount of a setof thata noisereduction of 5 dB(A)was obtained even though the situation neighborhoodnoisiness judgments. The modelis usedto relatethe growth wasnot in optimization.[Work supported by NNSF of China.] functionsfor judgmentsof neighborhoodnoisiness and the prevalenceof annoyanceto one another. 9:00 9:30 5aNS3. Designand effectivenessof in-line tuning cablesfor quieting hydraulic power units. JohnM. Dodson,David R. Dowling,and Karl 5aNSS.Quiet motor design. Cfineyt •ztiirk, EminS•nmez, Harun Grosh (Dept. of Mech. Eng. andAppL Mechanics,Univ. of Michigan, A•ikg;Sz,and Birdal G'6ok(TEE A.•, R&D Dept., Davutpa•a,Litros Ann Arbor, MI 48109-2125) Yolu 1, Topkapi34020, Istanbul,Turkey) The use of hydraulicunits to power tools,lifts, and otherindustrial Acousticmodeling of appliancemotors leads the product designers to equipmentin both indoorand outdoorsettings is widespread.The noise fullygrasp all thetechnical features of themotor that cause noise. Utilizing radiatedby theseunits and the hydrauliclines used to conveythe fluid completeanalysis packages during prototype development provides the continuesto be a problem.The dominantnoise components arise from capabilitiesof existingnumerical analysis software to enablethe designer pressurefluctuations in the hydraulicfluid ocurringat harmonicsof the to visualizethe influence of all mechanical,electromagnetic, and acoustic 2578 J. Acoust.Soc. Am., VoL 99, No.4, Pt.2, April1996 131stMeeting: Acoustical Society of America 2578 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 featureson the potential product. The purpose of thisstudy was to develop parametersthat cause the increaseof the audiblenoise and let themknow a methodologyto let the designerpredict all parametersincluding me- the factsof usingpredictive design tools in an efficientand correct way on chanicalresonances, electromagnetic forces, and aerodynamicand acous- thebasis of developedmethodology. The resultof thisresearch is a design tic featuresthat dominate noise spectrum of actualprototypes, during the methodologythat leads to the developmentof low noise productsand developmentstage. This methodenables the designerto be aware of all efficient use of potentialdesign tools. FRIDAY MORNING, 17 MAY 1996 REGENCY C, 8:00 A.M. TO 12:10 P.M. Session 5aPA PhysicalAcoustics: Resonant Ultrasound Spectroscopy I Albert Migliori, Chair Los Alamos National Laboratories, MS-K764, PO. Box 1663, Los Alamos, New Mexico 87544 Chair's Introduction---8:00 Invited Papers 8:10 5aPA1.Temperature variation of elasticityof or-quartzby the rectangularparallelepiped resonance method. lchiro Ohno (Dept.of EarthSciences, Ehime Univ., Bunkyou-cho 2-5, Matsuyama,790-77 Japan) The resonant trasoundspectroscopy of a specimenof a-quartzsingle crystal was carried out up to 558 øC, just belowthe a-fl transition( 0=573 øC), and all of the independentelastic constants were determinedsimultaneously by the rectangular parallelepipedresonance method. The results show that bulk moduli decrease largely toward T 0, whilethe shear moduli show only slightdecreases. The constant, Cv,, characteristicof trigonal crystals, decreases tojust below T 0, butit seemsnot to vanish,but to remaina finitevalue, even at To. It is notedthat the isotropic aggregate of a-quartzis a curiousand scarce material, in thesense that its bulk modulusis smallerthan the shearmodulus, and Poisson's ratio is very smallor evennegative at temperatureshigher than 450øC. The effect of piezoelectricityof a-quartz on the theoretical frequencies was investigated inorder to know whether the ordinary nonpiezoelectrictheory gives considerably inaccurate resonance frequencies. It was shown that the nonpiezoelectric theory gives a frequencylower than the frequencygiven by piezoelectrictheory, but the differenceis 0.5% at most. 8:40 5aPA2. The determinationof physicalproperties at high pressureusing a high-temperaturedatabase from resonant ultrasoundspectroscopy (RUS) measurements. Orson L. Anderson,Hyunchae Cynn, and Donald G. lsaak (Inst.of Geophys.and Planet.Phys., UCLA, LosAngles, CA 90095-1567) Usingthe RUS technique called rectangular parallelepiped resonance, a large database on elastic constants and associated ther- tooelasticparameters extending from 300 K upto ashigh as 1800 K (P=0) hasbeen established at UCLA. Temperature derivatives ofthe Cij's have been determined with considerable precision. It has been shown how the pressure derivatives ofelastic constants (•Cij/JP)r canbe approximated from(r•Cij/c)T) p. Agreement withexperiment isquite good in some cases. Extending thismethod to highpressure (>3 GPa)requires evaluation of thevolume dependence of the parameter, (c)P/dT)v = aKr, wherea is thermal expansivityand K r is theisothermal bulk modulus. Again, this is donefrom temperature Cij data,but it requiresone datum on pressure,K• = (()Kr D)P)r(P = 0). Fromthe data, the temperature atwhich aK r becomesindependent of volume was predicted. The theoryagrees well with experiment for all solidstested (NaCI, MgO, AI20_•, Mg2SiO4, CaO). 9:10 5aPA3.New pressure measurements of elasticity using the rectangularparallelepiped resonance method. DonaldG. Isaak, O. L. Anderson,J. D. Cames,and H. Cynn (Inst.of Geophys.and Planet. Phys., UCLA, Los Angeles, CA 90095-1567) Therectangular parallelepiped resonance (RPR) method has proven to be aneffective means to measurethe adiabatic elastic moduli,C0 , atvery high temperatures. Theextension ofthe RPR technique toelevated pressure isan attractive proposition because bondingproblems associated with coupling between transducers and specimens are essentially eliminated. However, RPR data have notyet been reported at elevatedpressure because of (1) thesmall frequency shifts observed over the accessible pressure range, and (2) complicationsin the data reduction scheme by which primary measurements of a resonance spectrum are interpreted in terms of thespecimen Cq's. The experimental andanalysis problems encountered when pressure dependences of modal frequencies are measuredwill bediscussed, and ways in whichthese problems can be overcome will bepresented. A new apparatus in which RPR measurementsatelevated pressure have been made will be described. Initial RPR pressure data on several materials will be presented andcompared toresults obtained when using thermodynamic considerations thatrelate the temperature dependences of the resonant frequenciesto theirpressure dependences. 2579 J. Acoust.Soc. Am., Vol. 99, No.4, Pt.2, April1996 131stMeeting: Acoustical Society of America 2579 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 5aPA4, Resonantultrasound spectroscopy and Raman measurementsto examine cation order-disorder. HyunchaeCynn, OrsonL. Anderson,and Donald G. Isaak (Inst.of Geophys.and Planet. Phys., UCLA, LosAngeles, CA 90095-1567) The elasticconstants of naturalMgAI204 spinelhave been measured using resonant ultrasound spectroscopy at high temperature. Below 1000 K, the ultrasonicresonant frequencies of an orderednatural spinel change significantly after heat treatment. The Raman spectrafor orderednatural and disordered spineIs also differ below 1000 K butare similar at highertemperatures and after cooling to ambienttemperature. These changes in ultrasonicresonance and Raman spectra of spinelcan be associatedwith cationdisordering at high temperaturethat may be quenchedby cooling.The estimatedinversion parameters from the relativeintensities of the two AI g Ramanmodes are in very goodagreement with estimatesfrom othermeasurements. It is foundthat C• andCl2 decreaseby 4% and 8%, respectively,with 20% inversionin spinel;C44 is lesssensitive to cationdisorder. These results imply thatprevious measurements of the adiabaticelastic constants of spineIsat ambientconditions have beenaffected by the stateof cationdisorder of the specimen. 10:10-10:40 Break Invited Poster Papers Authorsof papers5sPA5 and 5aPA6will be at their postersduring the break. 5aPA5. Measurementsfor pressureand temperature dependenciesof elastic moduli by the resonantsphere technique,RST. IsaoSuzuki, Tomonori Fujio, Hiroshi Kikuchi, Hitoshi Oda (Dept.of EarthSciences, Okayama Univ., Okayama,700 Japan),and IchiroOhno (EhimeUniv., Matsuyama, 790-77 Japan) Theresonant sphere technique, RST, has been developed for measurementsof elasticity and artelasticity of smallcrystal specimens. This methodhas advantagesover othermethods, especially in high-temperatureand high-pressuremeasurements. New methodsof dataacquisition have made it convenientto measureresonance frequency at hightemperatures (using a bufferrod), making a I K temperatureinterval measurement possible; this opens up manypossibilities in the determinationof physicalproperties of solids. Preliminarymeasurements of resonancefrequency were performed by RST up to 100 MPa, whichshowed interference of vibration modesbetween the specimenand the pressuremedium, even for heliumgas as the pressuremedium. This interferencemay become moreserious at higherpressures or underliquid pressure. In orderto evaluatesuch effects, the cavity resonance method was developed by Ohnoin 1993,with a sphericalshell structure with a sphericalspecimen at thecenter. This givesclear boundary conditions in the wave equations.Theoretical evaluation of the resonantfrequency on sucha systemshows the necessityof correctionto pressure derivativesof elastictoodull, even in measurementsup to 100 MPa. 5aPA6. Simultaneousdetermination of elasticconstants and asphericityof asphericalspecimen by the resonantsphere technique.Hitoshi Oda (Dept.of EarthSciences, Okayama Univ., Okayams, 700 Japan) Theresonant sphere technique (RST) is a methodof resonantultrasound spectroscopy developed to measureelastic constants of solids.In thismethod, resonant frequencies of a sphericalspecimen are measuredand the elasticconstants are determinedby comparingthe measured frequencies with theoretical ones that have been computed for a setof elasticconstants. A perfect sphere is not alwaysobtained, however; the specimensometimes has small aspherictry. In this case,the effectof aspbericityon the resonant frequencieshas to be corrected.Thus a methodhas been developed to determinesimultaneously the elastic constants and aspherictry of an asphericalspecimen. When RST is employedfor elasticitymeasurements of an ellipsoidalspecimen, the differencebetween measuredand computed resonant frequencies is expressed by &o--qS,ei+AoBCo, wheresummation convention is assumedfor repeatedindices, and ei and3Ci• (i,j=x,y,z) areasphericity of theellipsoid and small corrections for a setof elasticconstants, respectively.Since the coefficients q•iand A 0 areknown, the unknown coefficients ei and •C 0 canbe determined bya least-squares method.Actual application will be reportedfor an ellipsoidof an olivinespecimen with orthorhombiccrystal symmetry. ContributedPapers 10:40 regionshowed a slopeof approximately3.5 timesthat of the lowerstrain region.A dislocation-modelexplanation will beoffered for higherQ • at 5aPA7. Voigt stlffnessesand amplitude-dependent internal friction in higher e. ruonocrystal silicon. Hassel Ledbetter, Sudook Kim, Christopher Fortunko (NIST, 325 Broadway,Boulder, CO 80303), Paul Heyliger (Colorado State Univ., Fort Collins, CO 80523), and Mitsuru Tanaka 10:55 (NRI.3M,Tsukuba, Ibaraki, 305 Japan) 5aPA8. Transducersand measurementsat high temperaturesusing resonantultrasound spectroscopy. Timothy W. Darling and Albert The specimenconsisted of a 1-cm-diammonocrystal silicon sphere. Migliori (LosAlamos Natl. Lab.,I_os Alamos, NM 87545) Voigt elasticstiffnesses Cl•, Cl2, Cnawere determinedfrom the macro- scopiceigenvibration frequencies. The Ci.i results agree closely with pre- Resonantultrasound spectroscopy (RtJS) measurementsof material viousmeasurements by conventionalacoustic methods. The internalfric- propertiesathigh (above 150 øC} temperatures have been directed mainly tionsQ- i weredetermined fortwo nondegenerate eigenfrequencies. One at materialsof geologicalinterest, but a widevariety of otherapplications dependsonly on the shearmodulus C44. The other,composed of existsfor high temperatureRUS measurements.These include physical 0-64Cl1+0.32 Cl'•+0.04 Cna, is nearlyindependent of Cn4. Granato- properties(phase transitions, elastic reedall) of novelsolid state materials Litekeplots of Ine Q- • vsIn e- • showedtwo regions. The higher strain andunderstanding and control of processingparameters for industrial 2580 J. Acoust.Soc. Am., Vol. 99, No.4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2580 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 terialssuch as ceramics and steels. A RUSmeasurement system has been Gaunaurdand H. Huang,J. InverseProblems Eng. (in press,1996)], and it developedwhich operates to 600øC without buffer rods. A descriptionof will be illustratedwith many measuredand computationallypredicted thematerials used and the transducer construction will be presentedwith graphs.These techniques may provide the basicphysical explanation of the someresults from measurements on perovskite-typecrystal structures and dolphin'samazing target-ID feats. magneticmaterials. A discussionof the limitsof the presentsystem and possibletechniques for bufferlesstransducers with operating temperatures to 1000øC will bepresented. [Work supported by theU.S. Departmentof Energy.] 11:40 5aPAll. Characterization of inertial confinement fusion targets. ThomasJ. Asaki,James K. Hoffer,and John D. Sheliak (MS K764, Los lh10 AlamosNatl. Lab., Los Alamos,NM 87545) 5aPA9. Resonant ultrasound spectroscopy investigation of a Prototypeinertial confinement fusion targets for theproposed National first-order structural phasetransition in LiKSO4. F.A. Willis and Ignition Facility are metallicor plasticspherical shells (2 mm o.d., R. G. Leisure (Dept. of Phys.,Colorado State Univ., Ft. Collins,CO • 150-ramthickness) with an •80-mm-thick layer of soliddeuterium- 80523) tritium(50/50 mixture) deposited on the innersurface. Ignition will occur only if the D-T fuel layer meetsstrict sphericity and surfaceroughness Lithiumpotassium sulphate (LiKSO4) exhibits a richvariety of struc- criteria(typically • 1 mm).Symmetric layering of solidD-T occursdue to turalphase transitions. Ten differentphases have been reported over the the phenomenonof "beta layering"in whichtritium-induced self-heating temperaturerange from approximately 4 to 1000K. The roomtemperature drivesthe redistributionof material.In contrastto the opticaltechniques phaseis hexagonalP63 . On cooling,the room temperaturephase trans- usuallyemployed, this work discussesmethods in which resonantultra- formsat approximately205 K to anotherphase which is now believedto soundspectroscopy (RUS) and relatedtechniques can be usedto help be trigonalP31c, although the symmetryof thisphase has been controver- determinethe uniformityof the fuel layer insideopaque targets. A tetra- sial.Resonant ultrasound spectroscopy has been used to measurethe com- hedralarray of pinducersin a cryogenicapparatus is usedto both mount pleteset of elasticconstants of LiKSO4 overthe temperaturerange of 200 and probethe sample.Preliminary efforts have focusedon the character- to 300 K. The roomtemperature elastic constants are accuratelydescribed ization of solid spheresand both aluminum and beryllium shells. Suffi- by hexagonalsymmetry. At approximately213 K on coolingthere are large cientlyhigh Q's (103- 105)necessary for detailedwork are readily ob- abruptchanges of as muchas 80% in manyelastic constants. The elasticity tained.Studies involving deuterium-filled shells include the observationof of this phasecannot be describedby hexagonalsymmetry, but trigonal liquidcondensation, triple pointmeasurement, and the effectsof thermally symmetryfits the data well. The elasticconstants return to the hexagonal induced redistribution. valuesat approximately243 K on warming.The resultswill be discussed in termsof Landautheory. [Research supported by NSF underGrant No. DMR-9501550.] 11:55 11:25 5aPA12. An application of resonant-ultrasoundspectroscopy using a discrete-layercontinuum theory. Paul R. Heyliger (Dept. of Civil 5aPA10. Ultrasonic spectroscopytechniques used by dolphins to Eng., ColoradoState Univ., Fort Collins,CO 80523), HasselLedbetter, characterize resonatingsubmerged elastic shells. G. C. Gaunaurd,D. and SudookKim (NIST, Boulder,CO 80303) Brill, H. Huang (Naval SurfaceWarfare Ctr., White Oak, Silver Spring, MD 20903-5640),P. W. B. Moore (Naval Command,Control and Ocean The majorityof analysismethods for the computationof naturalfre- SystemsCtr., NRaD, San Diego, CA 92152-6267),and H. C. Strifors quenciesrequired by ultrasonicresonance spectroscopy is basedon varia- (National DefenseRes. Establishment,S-17290, Stockholm,Sweden) tional methodsof approximationthat incorporatebasis functionswith C- • continuityatevery point within the domain. When used for laminated The pulsed echoesreturned by several submergedcylindrical shells materialsof differentconstitution, the continuousstrain field implied by insonifiedby the peculiarsound pulses ("clicks") emittedby dolphins such approximationscannot represent true behaviorat an interfacebe- have been examined.These clicks and echoeswere collectedin a large tween the materials.A discrete-layertheory is developedin this study databaseas is donein standarddolphin experiments [Animal Sonar: Pro- which introducespiecewise approximations in the layereddirection of the cessesand Performance,edited by P. Nachtigall and P. W. B. Moore solid,allowing for a moreaccurate portrayal of the strainfield. The vibra- (Plenum,New York, 1988)].The emphasishere is on the processingand tional modescan be groupedinto four groupsrather than the eight that are physical interpretationof the ultrasonicspectroscopic features in these typical for an orthorhombicmaterial. The model is usedto studya seven- dolphin-generatedechoes. These resonancefeatures actually permit the layer laminate composedof layers of aluminum and aramid/epoxy.Two total characterizationof the shells.The spectroscopic"lines" (i.e., reso- geometriesare considered:a plate and a parallelepiped.The frequencies nanceswith widths)in the frequencysignatures, as well as otherfeatures predictedby the discrete-layertheory are comparedwith measurements in the associatedtime-domain signatures, provide all the ingredientsre- and frequenciesfound using a more conventionalRitz methodwith the quiredto determinethe size, shape,thickness, shell elasticmaterial, and effectiveproperties of the material.The discrete-layerfrequencies tend to internalfiller material,in all cases.The time and frequencyprocessing of be slightlylarger than those computed using the Ritz methodfor the plate the echoesis explained in detail; it follows the pattern briefly outlined and slightlylower for the parallelepiped.Implications for the useof this elsewhere[G. C. Gaunaurd,J. Opt. Eng. 31, 2253-2261 (1992); G. C. theory are discussed. 2581 d. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society of America 2581 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, 17 MAY 1996 REGENCY A AND B, 8:00 A.M. TO 12:15 P.M. Session 5aPP Psychologicaland PhysiologicalAcoustics: Cochlear Mechanics Peter Dallos, Cochair FrancisSearle Building, Northwestern University, 2299 SheridanRoad, Ewmston, Illinois 60208 Glenis R. Long, Cochair Departmentof Audiologyand SpeechScience, Purdue University, West Lafayette, Indiana 47907 Chair's Introductions8:00 Invited Papers 8:05 5aPP1.A reviewof activeand passivebasilar membrane cochlear mechanics, Jont Allen (Acoust.Res. Dept., AT&T Bell Labs., MurrayHill, NJ 07974) SinceDavid Kemp first proposed the activemodel in 1979,the role of the outerhair cell (OHC) in basilarmembrane (BM) mechanicshas been hotly debated.In the "active"model view, the OHC modulatesthe motionof the BM travelingwave on a cycle-by-cyclebasis, leading to a negativeBM resistanceand a traveling-wavepower gain. Nonlinearity is introducedby assuming thatthe negative BM resistancedepends on the signallevel. In the "passive"model view, the OHC controlsthe stiffnessof thebasilar membrane,leading to a level-dependent(nonlinear) relative impedance between the BM and teetorialmembrane and a nonlinear basilarmembrane and transductionresponse. Both modelsseem to he able to achievethe importantnonlinear variations in responses seenin the BM, OHC, IHC, and neuralresponse, but with differingassumptions and degreesof physicalreality. It is now clear that the OHC nonlinearlycompresses both the dynamicrange of basilarmembrane motion (Rhode, 1971; Ruggero, 1990) and the neural response(Yates, 1989), extending the otherwise limited dynamic range of the [HC response.This role of theOHC maybe quantified usingpsychoacoustic masking patterns, two-tone suppression, loudness growth and recruitment,and OAEs as objectivemeasures. 8:35 5aPP2.Cochlear nonlinearity: Implications for auditorysignal processing and perception. HendrikusDuifhuis (Biophys.Dept. & BCN (Grad.School for Behavioraland Cognit.Neurosci.), RUG, Nijenborgh4, 9747 AG Groningen,The Netherlands) Consciousperception of auditorynonlinearity in combinationtones, the low-frequencyintermodulation products of two or more tones,goes at leastback to Tartini(1692-1770). Renewed interest around 1970 [e.g., J. L. Goldstein,J. Acoust.Soc. Am. 41,676-689 (1967);J. L. Hall, J. Acoust.Soc. Am. 56, 1818-18280974); G. E Smoorenburg,J. Acoust. Soc. Am. 52, 615-632 (1972)]led to theconclusion that the nonlinearityoriginates in the (intact)cochlea. At thattime, nobody paid special attention to the pointthat acousticaleffects within the cochlea should be reflected at theaural entrance. Today, that issue (DPOAE) is activelyexplored. The link with auditoryperception receives lesser emphasis, hopefully not becausea properpsycheacoustic measurement requires more than readinga stimulusparameter (cf. Psychoacousticsand David M. Green).Next, two-tone suppression became an issuewhere psycho- logicaland physiologicalnonlinear acoustics met. The phenomenaare intertwined,and probably inseparable from the pointof view of underlyingbiophysical mechanism. Finally, obviously the auditorynonlinearity is compressive.The negligibleimpact of thisresult on developmentof a biophysicalbasis for the auditorydynamic range and the decihelscale remains puzzling. 9:05 5aPP3. Otoacousticemissions as tools to probe cochlearfunction. Glenis R. Long (Dept. of Audiol. and SpeechSci., Purdue Univ., WestLafayette, IN 47907), CarrickL. Talmadge,and ArnoldTubis (PurdueUniv., WestLafayette, IN 47907) Otoacousticemissions (acoustic signals originating in thecochlea) can be noninvasivelyevaluated by placinga sensitivemicro- phonein the ear canaland extracting the emissionsfrom the noiseby signalanalysis. Since first reported (Kemp, 1978),otoacoustic emissionshave been developed into a very usefulexperimental tool for probingcochlear function. A researchoverview will give specialattention to theexistence of a strongperiodicity in thefrequency domain in all humanotoacoastic emissions. This periodicity will he relatedto maximaand miniran seen in heatingthreshold measurements. Discussion will focuson thehypothesis that the basis for the pseudoperiodicnature of the emissionsis the coherentscattering from cochlearirregularities within the tall andbroad peak of thetraveling wave [cf. Sheraand Zweig, J. Acoust.Soc. Am. 98, 2018-2047(1995)]. This scattering gives rise to a reflectionof the cochlearwave towardsthe base,whose effects are detectablein the ear canalsignal. The pseudoperiodicproperties of emissionsare governedby the nearlylinear frequency dependence of the phaseof thecochlear traveling wave ratio, which is mainlydetermined by thecomplex wavelength of thetraveling wave in thepeak region. [Work supported by NIDCD.] 2582 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2. April1996 131stMeeting: Acoustical Society of America 2582 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 5aPP4.Mechanical responses of the basilarmembrane. AlfredL• Nuttall (KresgeHear. Res. Inst., Univ. of Michigan,1301 E. Ann St, Ann Arbor, MI 48109-0506) The traveling-waveactivity that Georg von B6k6systudied in thecochlea early in thiscentury has been of intenseinterest to physiologistsand mathematical modelers over the last 30 years.This interest was nurtured by thediscovery that the mechanical responsesof the basilar membrane are nonlinear at relativelylow sound levels and that the nonlinearity is dependent on biological processes[W. S. Rhode,J. Acoust. Soc. Am. Suppl. I 49,S1218 (1971)]. This review will brieflysummarize the major findings of the earlyyears as background to a presentationof several issues that are the focus of contemporarywork. The steady-state and transient velocityresponses of the basilar membrane characterize the capacity of thebiological amplification mechanism in the organ of Corti andindicate that a "gain"of 40-60 dB is providedby the outer hair cells. Considerable response distortion accompanies this gain, andwave propagation of certain distortion products occurs. Electrical stimulation of theouter hair cells provides evidence of their mechanicalrole in the amplificationmechanism by demonstrationof the frequencyrange and displacementcapacity of the cells. Efferentinnervation of the organof Coni is foundto modulatethe mechanicalactivity of the system. 10:05-10:20 Discussant George Zwelg Los Alamos Natl. Lab., MS B276, T-Dot, P.O. Box 1663, Los Alamos, NM 87545 10:20-10:30 Open Discussion ContributedPapers 10:30 fromimplanted electrodes. The data indicate a small(< 10dB) permanent thresholdshift (PTS) in the 10- and 100-s 1SI conditions.For the l-s ISI 5aPP5. Inner hair cell and organ of Corti responsesto very low conditions,the animalsexposed at 129dB experiencedmore than 25 dB frequencytones. M.A. Cheathamand P. Dallos (HughKnowles Ctr., PTS at highfrequencies. Animals exposed at 120dB exhibitedlarge tem- 2-240 FrancesSearle Bldg., 2299 N. CampusDr., NorthwesternUniv., porarythreshold shifts (TTS) whilethe animalsexposed at lowerlevels Evanston, IL 60208) hadsmaller TTS andminimal PTS. Stimuluslevel and ISI hadsignificant The timing of excitationobserved in the auditorynerve exhibits a effectson the PTS while frequencycontent was not significant. strongdependence on bestfrequency (BF). Fibersinnervating the baseof thecochlea respond to nearthreshold, low-frequency inputs approximately 11:00 in phasewith basilarmembrane velocity to scalatympani while fibers innervatingapical regions respond in phasewith basilarmembrane veloc- 5aPP7. Neural representationand psychophysicaldiscrimination of ity to scalavestibuli [M. A. Ruggeroand N. C. Rich,J. Neurophysiol.58, vowel formants. BradfordJ. May (Dept. of Otolaryngol.-HNS,Johns 379-403 (1987)]. Althoughthe latter is consistentwith the velocityde- HopkinsUniv., Baltimore, MD 21205)and RobertD. Hienz (Johns pendenceof innerhair cells (IHC) andwith theclassical view of haircell HopkinsUniv., Baltimore, MD 21205) stimulation,the responsephase of singleunits in the baseof thecochlea Auditory-nervefiber responses were modeled to estimateneural rep- hasbeen difficult to explain.Consequently, IHC recordingsfrom the sec- resentationsof frequencychanges in the secondformant (AF2) of the ondturn of theguinea pig cochlea (BF = 4000Hz) wereused to determine steady-statevowel /eh. Simulationswere performed at vowellevels of phasesof depolarizationrelative to basilarmembrane displacement. To 33-84 dB,both in quietand in continuousnoise at a constant3-dB signal- betterestimate synaptic drive, the organof Corti responsewas subtracted to-noiseratio (S/N). Signaldetection analysis of modeloutputs suggested from that recordedin the IHC since the voltage gradientthat induces that formantchanges at higherstimulus levels and in backgroundnoise transmitterrelease can be influencedby extracellularresponses that reflect werebetter represented by rate responsesof fiberswith low spontaneous receptorcurrents generated in nearbyouter hair cells. Results indicate that rates(SR). Psychophysicaltests were then performed in catsto measure IHC depolarizationoccurs near basilar membrane velocity to scalatym- behavioralthresholds for thedetection of formantfrequency changes under paniconsistent with single unit excitation in thebase of thecochlea. [Work stimulus conditions similar to those of the neural simulations. Behavioral supportedby GrantNo. 5R01DC00089,National Institute on Deafnessand AF2's wereobtained at vowellevels of 10-70 dB, in quietand in con- OtherCommunication Disorders.] tinuousbackground noise at S/Nsof 3, 13,and 23 dB.AF 2 decreasedwith increasingvowel level and increased with decreasingS/N. Thesetrends in psychophysicalperformance paralleled changes in the qualityof vowel 10:45 representations,particularly those based on dischargerates of low SR 5aPP6. Impact noise exposurein chinchilla:Effects of frequency, auditory-nervefibers. [Work supportedby NIDCD Grant Nos. level, and interstimulus interval. Rickie R. Davis and William J. 5R01DC01388-04and 2R01DC00109-22.] Murphy (Bioacoust.and Occup. Vib. Sect.,Natl. lnst.for Occup.Safety andHealth, MS C-27,4676 Columbia Pkwy., Cincinnati, OH 45226-1998) 11:15 The effectof impactnoise on hearingthreshold was investigatedin a 5aPP8. Perceptionof amplitude fluctuationin the goldfish. M. parametricstudy which manipulated frequency, level andinterstimulus Chronopoulos,R. Fay,R. Dye (ParrelyHear. Inst. and Dept. of Psych., interval (IS1). The chinchillapinna passivelyamplifies acoustic stimuli LoyolaUniv.-Chicago, 6525 N. SheridanRd., Chicago,lL 60626),S. between2 and 6 kHz suggestinggreater effects in that frequencyrange. Sheft,and W. Shofner (ParrelyHear. Inst., Chicago, [L 60626) Exponentiallydecaying pulses (t = 40 ms)with carrier frequencies of 1, 3, and8 kHz werepresented at peakpressure levels of 114,117, 120, and 129 This experimentinvestigates the extentto whichthe goldfish'sre- dB SPL and ISI of 1, 10, and 100 s. The chinchillaswere exposed for 8 h, sponseto amplitude-modulatedandphase-manipulated sounds can be pre- withone animal per condition. Hearing function was assessed by measur- dictedby thepower of envelopefluctuation. Sixteen common goldfish, ingauditory-evoked potentials from tonebursts at 0.5, 1, 2, 4, and8 kHz Carassiusauratus, were classically conditioned to suppressrespiration to 2583 J. Acoust.Soc. Am., Vol. 99, No.4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2583 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 350-Hzcarder 100% sinusoidally amplitude modulated at 30 Hz. In a constructedwith differing time intervals between the twohigh-current subsequentlygeneralization test session, respiratory suppression was mea- pulses,and a furthersix stimuli were unmodulated pulse trains with rates suredin thepresence of novelsignals having either sidebands attenuated or between100 and 250 Hz. All stimuliwere loudness balanced and pre- carrierphases shifted up to 90 ø. Respiratorysuppression declined with sentedto thesubjects in a single-intervalpitch ranking task. The unmodu- bothincreases in sidebandattenuation and increases in phaseshift of the carrierfrequency. Respiratory responses to both sidebandattenuated and latedstimuli showed a monotonic increase in pitch with rate. The pitch of phase-shiftedsignals declined along a single,monotonic function of en- themodulated stimuli was mostly determined by thelonger of thetwo velopepower as defined by thenormalized fourth moment [W. Hartmann intervalsbetween the high cun:ents. When the high currents were very and1. Pumplin, J. Acoust. Soc. Am. 90, 1986-1999(1991)]. The goldfish's close,the modulation period was also important in determiningthe pitch. performancein thisexperiment is comparableto theperformance of hu- Thesecond experiment used constant-current pulse trains with two pulses man listenersin experimentson roughnessscaling [C. Mathesand L. in every 20 ms. The effect on loudnessof the interval betweenthe two Miller,J. Acoust.Soc. Am. 19, 780-797(1947)]. [Work supported by a pulseswas measured using loudness balancing. For interpulseintervals NIH, NIDCD ProgramProject Grant to theParmly Hearing Institute.] lessthan 4 ms the loudnessincreased as the intervaldecreased. This result impliesthat a facilitatoryeffect dominates over any refractory effect on 11:30 loudnessat shortinterpulse intervals. 5aPP9.Perception of musicalpitch with electricalstimulation of the cochlea. Hugh J. McDermottand ColetteM. McKay (Dept. of Otolaryngol.,Univ. of Melbourne,Parkville, 3052 Australia) For cochlearimplant users to obtainenjoyment from music,it is es- 12:00 sentialthat they be ableto perceivemelodic pitch. Previous studies have 5aPPll. Effects of meclizine in young adults, measuredwith indicatedthat the "pitch" or timbreof pulsatileelectrical stimuli varies withthe repetition rate or intracochlear siteof delivery,but generally pitch otoacousticemissions, REPs/ABR, qEEG, and a computerizedtest of hasbeen defined loosely as a tonalquality that can be rankedin termsof eye-hand coordination. JudithL. Lauter,Suzanne B. Wood,Onita "sharpness."In a recentseries of experiments,a user of the Nucleus Lynch,and Kaye Agnew (Dept.of Commun.Sci. and Disord., P.O. Box 22-electrodeimplant was asked to judgeor adjustthe musicalinterval 26901,825 N.E. 14thSt., Univ. of OklahomaHealth Sciences Ctr., betweenpairs of stimuli.The electrical parameters investigated included OklahomaCity, OK 73190) thefrequency of sinusoidallyamplitude-modulated pulse trains, as well as pulserate and active electrode position. The subject was able to judge the Twelve neurologicallynormal young adults were testedbefore and pitchesusing only the interval names ("fifth" "octave,"etc.), and without after administrationof meclizine,an over-the-countermedication for mo- specifictraining, the guidance of familiarmelodies, or rhythmcues. The tionsickness. The batteryconsisted of fourcomponents: (1) repeated- resultsshowed that rate or modulationfrequency could convey musical pitchover a rangeof approximatelytwo octaves,and followed a relation- measuresdistortion-product otoacoustic emissions (DPOAEs); (2) the shipcomparable with that for acousticstimuli and normal hearing. The repeated-evoked-potentialsversionof the auditorybrain-stem response pitchrelated to electrodeposition could also be labeledin musicalterms. (REPs/ABR);(3) quantitativeelectroencephalography (qEEG)measured Interestingly,when both place and rate varied together, the pitch associated overleft- and right-side auditory cortex; and (4) a computer-basedeye- with electrodeposition was generally dominant. handcoordination task. The battery required approximately 1.5h to com- plete.Each subject was tested with the battery ineach of eight longitudinal 11:45 sessions:three times on a controlday (no medication); the same times on a secondday one week later (medication atmid-day); and 24- and48-h 5aPPI0. The effecton pitch and loudnessof major interpulse check-upsessions following the medication day. Results show dramatic intervals within modulated current pulse trains in cochlear changesin all batterycomponents, with details suggesting the site(s) of implantees.Colette M. McKayand Hugh J. McDermott(Dept. of actionof thistype of antihistamine.The "auditory-system cross sections" Otolaryngol.,Univ. of Melbourne,Parkville, 3052 Australia) yieldedby this battery make it possibletoobserve effects from periphery Twoexperiments were completed with five subjectswho have been to cortex,including evidence linking otoacoustic emissions with central implantedwith the Mini System22 cochlearimplant. In thefirst experi- auditoryphysiology. Implications range from cautions regarding the acute ment,1000-Hz pulse trains were modulated so that there were two high- effectsof antihistamines,to physiological support for using such medica- andeight low-current pulses in each10-ms period. Five stimuliwere tionsto improveperformance in leaming-disabled children. 2584 J.Acoust. Soc. Am., Vol. 99, No. 4, Pt. 2, April 1996 131stMeeting: Acoustical Society ofAmerica 2584 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, 17 MAY 1996 CELEBRATION A, 8:00 A.M. TO 12:05 P.M. Session 5aSA Structural Acousticsand Vibration: Acousticsof Coupled StructuresI J. Adin Mann III, Chair AerospaceEngineering and EngineeringMechanics, Iowa State University,Ames, Iowa 50011 Chalr's Introduction-•8:00 Invited Papers 8:05 5aSA1. Joint effectsin the mid-frequencyvibration of connectedplates. T Igusa (Dept. of Civil Eng., NorthwesternUniv., Evanston,IL 60208) Structure-bornenoise in coupledsystems has been shown to be highlysensitive to joint properties.In thispresentation, the effects of joint behavioris examinedfor coupledplates joined in thecanonical L-shaped configuration. The effectsof the variationof thejoint propertieswith respect to thecoordinate axis along the two-plate junction is of interest.Mid-frequency loads are used, where the modal densityis not sufficientlyhigh for standardstatistical energy analysis. The problemis analyzedusing several methods. A mobility approach[J. M. Cuschieri,J. Acoust.Soc. Am. 87, 1159-1165(1990)] is usedas a benchmark,which, for thethin-plate model, is exact exceptfor modetruncation. The problemis thenexamined in theperspective of the followingtwo approximatemethods: a spatialand te•nporalaveraging method using energy and intensity as the primary field variables [O. M. Boutbierand R. J. Bernhard,AIAA J. 30, 616-623 (1992)]and an asymptotic method, based on Skudrzyk'sMean Value Theory IT. Igusaand Y. Tang,AIAA J. 30, 2520-2525 (1992}].It is foundthat the effectsof the variationsin thejoint propertiescan be interpretedusing wave vectordecompositions. 8:35 5aSA2.Structural acoustic energy finite element method. FernandoBitsic and Robert J. Bernhard(1077 Ray W. HerrickLabs., Schoolof Mech. Eng., PurdueUniv., WestLafayette, IN 47907} A new numericalmethod, referred to as the energyfinite elementmethod, had beenpreviously developed to predictthe high- frequencyresponse of built-upstructural acoustic systems consisting of subsystemssuch as rods, beams, plates, and acoustic spaces. The methodologyfor predictionof behaviorin the subsystemsis basedon a diffuseenergy field approximation.Subsystems are coupledtogether using net energy flow and energy superposition principles. In thispaper, the structural acoustic coupling relationship for energyflow analysis of coupledplates and acoustical spaces is shown.The couplingapproach chosen for structuralacoustic radiationuses plate radiation efficiency. The approach has been implemented into an energy finite element model. The energy finite elementpredictions will be comparedto measuredresults for anacoustical enclosure with one flexible wall. 9:05 5aSA3.Fluid-loaded plate coupled to a distributedinhomogeneity--Review. Joseph. M. Cuschieri(Dept. of OceanEng., Florida AtlanticUniv., Boca Raton, FL 33431)and David Felt (DavidTaylor Res. Ctr., Bethesda,MD 20084) Theproblem of scatteringfrom a fluid-loadedplate structure coupled to a distributedinhomogeneity is considered. Results have beenpresented which include the platesurface velocity Green's function, the far-fieldand near-field scattered pressure, and the acousticand structural intensity. The distributed inhomogeneities considered varied both in type(mass or stiffness}and shape. In all instances,the perturbation due to theinhomogeneity, relative to theelastic characteristics of the plate, is small.In thecase of shape variations,the influence of "smoothness"atthe edges of theinhomogeneity, and of oscillationswithin the inhomogeneity distribution werealso considered. In this presentation, theresults that have been generated thus far, will bereviewed and general conclusions drawn fromthese results. It isshown that depending onthe frequency range of interest,the results can be significantly influenced bythe shape andtype of inhomogeneity.Stiffness inhomogeneities, in general, are less significant compared tomass inhomogeneities. However, in relativeterms, internal variations in the inhomogeneityshape are moresignificant for stiffnessinhomogeneities than for mass inhomogeneities.Alternate forms of presentingthe results will beexplored. [Work sponsored byONR.] 9:35 5aSA4.The vibro-acousticresponse of coupledstructures using hybrid analytic-numeric methods. Karl Groshand Peter J. Halliday(Dept. of Mech.Eng. and Appl. Mechanics, Univ. of Michigan,Ann Arbor, MI 48109-2125) A hybridanalytic-numeric formulation for the time harmonic structural acoustics problem is presented.The variational framework forthe seamless inclusion of analyticsolutions into the Galerkin finite element formulation for a fluid-loadedstructure and results of theapplication of this method are given. One goal of thisformulation isto increaseoverall efficiency by eliminating regions of the structurefrom the computational domain via an analyticrepresentation of the response. In thisway, the total degrees of freedom presentin theproblem will be reduced. This reduction in the degrees of freedomenables higher frequency, more complex problems to be solvedby decreasingmemory requirements and compute time. The analysisof complexstructures, comprised of structural 2585 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April1996 131st Meeting:Acoustical Society of America 2585 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 memberscoupled at joints, is facilitated by this approach. Using a discretizationof the equations of elasticityfor the joint, its response maybe represented toa desiredlevel of accuracy.The elasticity representation iscoupled to the reduced plate or shell theory producing anefficient model of thecomplete structure. The effect of thejoint and the level of modelingdetail required for thedesired fidelity of predictionfor thevibration and acoustic response of the systemare studied. 10:05-10:20 Break Contributed Papers 10:20 exceedsall the critical values,the plate may be locally unstableat all equilibriumpositions. In particular,it may jump from one equilibrium 5aSA5. Multiple-reference adaptive active noise control in positionto anotherin a randomfashion. These local instabilities are con- enclosures.Zane M. Rhea (Grad.Prog. in Acoust.and Appl. Res. Lab., trolledby structuralnonlinearities. Without the inclusion of structuralnon- Penn State Univ., P.O. Box 30, StateCollege, PA 16804), Scott D. !ineadties,the platemay haveonly one equilibriumposition, namely, its Sommerfeldt(Brigham Young Univ., Provo, LIT 24360},and Courtney undeformedone. The amplitudeof plate vibrationwould then grow un- B. Burroughs(Penn State Univ., State College, PA 16804) boundedlywhen the flow speedexceeds the critical value, known as ab- Noise controlof multiple noisesources in 3-D enclosuresremains a soluteinstability. With the inclusionof structuralnonlinearities, the plate concernin many applications.This is of particularinterest in vehicles, may havemore than one equilibrium position when the flow speedexceeds wheremultiple primary sources contribute to the soundfield insidethe the criticalvalues. Under this condition,plate vibration may seemchaotic, enclosure.When utilizing active noise control (ANC) systemsin these the overall amplitudeof flexuralvibration is neverthelessbounded. applications,multiple reference inputs are required. A comparisonof active noisecontrol with multipleand singlereference inputs of multiplenoise sourcesis presentedin a caseformat. Since most sources are structuralin origin,independent harmonic vibration of two of therectangular enclosure 11:05 wallsare used as the primarynoise sources. Although a multiplereference inputANC systemis muchmore successful at controllingmultiple noise 5aSA8. Enhancement of the transmission loss of panel structures sources,care must be takenin choosingthe referenceinputs. If the refer- through the application of segmented,resonant foam attachments. enceinputs are not independentthe ANC becomesineffective. Also, a case J. StuartBolton and Yeon June Kang (1077Ray W. HerrickLabs., School studyof sound-pressurereductions obtained for on and off resonanceof of Mech. Eng., PurdueUniv., WestLafayette, IN 47907-1077) boththe enclosure and the enclosure wails is presented.[Work supix>ned by theApplied Research Laboratory.] In noise control foam both the bulk solid and fluid phasesparticipate significantlyin the wave propagationprocess. Here it is suggestedthat resonancesof the foam'ssolid phase can be tunedto producesignificant 10:35 narrow-bandabsorption superimposed upon the broadbandattenuation characteristictypically offered by the fluid phaseof an elasticporous 5aSA6. Sound transmissionthrough an neroelasticplate into an material.Two approacheshave beenconsidered. In the first, aluminum acousticcavity.. RobertL. Clark and KennethD. Frampton (Dept.of massesare applied to smallpieces of foam(say, 25 mm squareand 6 mm Mech.Eng. andMaterial Sci., DukeUniv., Durham, NC 27708-0300) deep)that are then attached to a panel.Each piece of foamthen comprises The transmissionof turbulentboundary layer (TBL) pressuresinto a smallresonator whose natural frequency is essentiallydetermined by the acousticenclosures is very importantto the aerospaceindustry. This topic bulk stiffnessof the solidphase of the foam togetherwith the addedmass. is particularlyimportant in aircraft interior noise investigations.While It hasbeen found that the applicationof an arrayof foamresonators causes many studieshave been publishedconcerning TBL transmissionthrough the transmissionloss of the basepanel to be increasedover approximately elasticplates into acousticenclosures, few of thesestudies have considered an octave.In a secondapproach, a continuousfoam lining is segmented. the dynamiceffects of aerodynamicflow over the plate(i.e., aeroelastic- and a piece of perforatedmetal is applied to each segment.Again, a ity). This presentationinvestigates the modelingof an elasticplate subject narrow-band increase in transmission loss is observed, in this case com- to full potentialflow and TBL loadingon one side and coupledto a binedwith the broadband transmission loss increase normally produced by reverberantacoustic enclosure on the other side. The elasticplate and a layerof porousmaterial. acousticenclosure are modeledthrough a Rayleigh-Ritzapproach. The effectsof the externalfluid flow are modeledthrough a singularvalued decompositiontechnique which performsa systemidentification on an approximatenumerical solution to the full potentialflow equations.This 11:20 aerodynamicmodel is then coupledto the elasticplate/cavity model to form the completesystem. The primary focusof this investigationis the 5aSA9. Discontinuousconstrained layer dampingtreatments applied effectsof the externalflow on the soundtransmission through the elastic to a vibrating free-freebeam. Samk Uppal,Alison B. Flatau (Dept.of plate into the cavity.It is demonstratedthat external flow can significantly AerospaceEng. and Eng. Mechanics,Iowa StateUniv., Ames,IrA 50011), affect the systemdynamics and, hence,the soundtransmission. and TheodoreB. Bailey (Iowa StateUniv., Ames,IA 50011) The vibration responseto applicationof discontinuousconstrained 10:50 layerdamping (CLD) patchesto variedportions of a free-freebeam was studied. Since neither closed-form solutions nor finite element methods 5aSA7. Stability of clamped rectangularplates in uniform subsonic flow. JinshuoZhu (PerstorpComponents, 47785 W. Anchor Ct., canbe readilyimplemented for CLD analysiswith partialcoverage of a structureunder broadbandexcitation [C. T. Sun and Y. P. Lu, Vibration Plymouth,MI 48170) and ScanE Wu (WayneState Univ., Detroit,MI 48202) Dampingof StructuralElements (Prentice-Hall, Englewood Cliffs, NJ, 1995),pp. 318-362], an empirical approach was taken. The test object was This paperdepicts the stabilitycharts of rectangularplates clamped to a 26.5- x I- x l/8-in. steelbeam, and wassubjected to a chirp.The aim an infinite, rigid baffle in uniform subsonicflow. The correlationsamong wasto quantifythe relativeeffectiveness of variedlengths and positions of the critical flow speedsand the plate aspectratio, plate thickness/length CLD patchesin reducingthe responseof the first five resonantmodes of ratio, andplate/fluid density ratio are exhibited.Results show that when the the beam.Assessment of the potentialfor strainenergy dissipation was flow speedexceeds a criticalvalue, the platemay vibratearound an equi- madebased on the net displacementof the Ix:am (appropriatelyphased librium positionother than its undeformedone. When the flow speed modesummation), with relative phase of thesummed modes specific to the 2586 J. Acoust.Soc. Am., Vol. 99, No.4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2586 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 inputforce signal. Attempts were made to correlatethe effect of CLD on 11:50 eachmode to thetime-averaged percentage of strain energy for thatmode underthe treatment patch, coupled with the percentage of thebeam's strain 5aSAll. Spectral integral approach to radiation from fluid-filled energyunder the patch. [Work supported by NSE] boreholes. Rama Rao V. N., Henrik Schmidt, and J. Kim Vandiver (MIT, Dept. of Ocean Eng., 77 MassachusettsAve., Rm. 5-007, 11:35 Cambridge,MA 02139) 5aSA10.Spectral elements for acousticwave propagationthrough A hybridmodel for radiationfrom a boreholewhile drillinghas been thin-walled complex structures. Brian A. Bilodeau and James F. developed.A numericalmodel for propagationin a boreholeincluding a Doyle (Schoolof Aeronaut.and Astronaut., Purdue Univ., West Lafayette, drill pipe has been combinedwith the OASES frequency-wave-number IN 47907) modelfor propagationin layeredearth media, using the conceptof effec- Noisegeneration is an aspectof structuralimpacts not receivingmuch tive sources.Equivalent line sourcearrays that producethe samefar-field attention.Reasons for this includethe fact that the problemrequires ana- radiationas the boreholeare first computed. These are then introduced into lyzing the solid/fluidinteraction as well as the need to model extended the layeredearth model and the resultantseismic wave field is computed. regions.Spectral elements are developedfor analyzingacoustic wave The boreholemodes are excitedby a displacementsource at the bottom, propagationthrough thin-walled structures. Both flat- and curved-plate simulatingbit motionwhile drilling.In contrastto earlierwork the present elements,which incorporate the effectof fluid loadingon the structure,are modelincludes the drill pipe in the simulation,allowing for threepropa- developed.These elements exactly model the responsesover large do- mainsand throughtheir generalizednodes may be convenientlyjoined to gating modesat low frequencies.The model has been appliedto analysis modelcomplex structures composed of manysegments and faces. Results of the role of the formationcomposition in the radiationfrom the tube for the impactof fiat andcurved panel systems are presented.In addition, modes. The fundamental differences between the radiation into soft and the utilityof the spectralmethod for computingfrequency response func- hard formationsare discussedand demonstrated,including the formation tionsdirectly is demonstrated. of Mach conesalong the boreholein soft formations. FRIDAY MORNING, 17 MAY 1996 MT. RAINIER AND MT. MCKINLEY, 8:30 TO 11:30 A.M. Session 5aSC SpeechCommunication: Speech Perception, Word Recognitionand Talker Characteristics(Poster Session) Keith A. Johnson, Chair Departmentof Linguistics,The Ohio StateUniversity, 1712 Neil Avenue,Columbus, Ohio 43210-1298 ContributedPapers All posterswill be on displayfrom 8:30 to 11:30a.m. To allowcontributors an opportunityto seeother posters, contributors of odd-numberedpapers will be at theirposters from 8:30 to 10:00a.m. and contributors of even-numberedpapers will beat theirposters from 10:00 to 11:30 a.m. 5aSC1. Voice effects in implicit memory tasks. Julie M. Brown, 5asc2.Possible word boundary constraints onmultiple activation of CarolA. Fowler,and Jay G. Rueckl (Dept.of Psych.,406 BabbidgeRd., form-basedrepresentations of spokenwords. Paul A. Luce, Rochelle Box U-20, Univ. of Connecticut,Storrs, CT 06269 and Haskins Labs., S. Newman,and Emily A. Lyons (Dept. of Psych.,Park Hall, SUNY, New Haven, CT 06511) Buffalo,NY 14260) Spokenwords are easier to identifyif theyhave been heard recently. Thisphenomenon, known as repetition priming, can be usedto investigate Mostcurrent theories of spokenword perception (e.g., Cohort theory, the processesunderlying word recognition.Using an implicitmemory TRACE,Shortlist, Neighborhood Activation Model) propose that multiple paradigm,this studylooked at the effectof changingthe voiceof the form-basedrepresentations of wordsare activatedin memoryduring rec- speakeron repetitionpriming. Voice effects occur if repetitionpriming is reducedwhen a spokenword has been heard in differentvoices at study multipleactivation of wordsin fluentspeech or the constraintson activa- and test.Voice effects have been found in implicit memorytasks, such as tionimposed by informationwithin the speech signal. The degreeto which wordidentification and word-stem completion [B. A. Churchand D. L. wordboundary information in two-wordsequences may limit lexicalhy- Schacter,JEP:LMC 20, 521-533 (1994); S. D. Goldinger,doctoral disser- pothesesduring recognition was examined.Using a cross-modalpriming tation,1992]. This studyinvestigated if theseresults could be generalized technique,spoken two-word utterances, such as NOTE-RAIL, were pre- to otherimplicit memory tasks--specifically, lexical decision, naming, and a new task,auditory fragment completion. No voiceeffects were found ognition.sentedand Few theof activationthesetheories,of possiblehowever, lexical specify itemsthe spanningprecisenaturethe wordof with any of thesethree tasks. These results are problematicfor current boundary(e.g., TRAIL) wasinvestigated. The implicationsof theseresults accountsof wordrecognition and imply that as yet unidentifiedfactors for currenttheories of spokenword recognition will bediscussed. [Work control the occurrence of voice effects. supportedby NIDCD.] 2587 d. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2587 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 5aSC3. The segmentalrepresentation of words as revealedby speech(condition 2); however,no recognitionadvantage was found for primingin a lexicaldecision and namingtask. NancyJ. Palmerand wordsrepeated at the sameamplitude (condition 3). In experiment2, James R. Sawusch (Park Hail, SUNY, Box 604110, Buffalo, NY subjectsgave an additionalexplicit judgment a.s to whether"old" words 14260-4110) wererepeated in thesame voice (condition 1), rate(condition 2), or am- plitude(condition 3). Subjectsagain showed a recognitionadvantage for In previousstudies, a priming task was used to explorethe nature of the wordsrepeated in thesame voice and rate, but no advantageoccurred in segmentalrepresentation of words. The phoneticoverlap between primes the amplitudecondition. However, subjects in all threeconditions were and targetswas varied. When phonemes occurred in the samesyllable significantlyabove chance accuracy in recognizingwhether an "old"word positionin primeand target, responses to the target were faster than when wasrepeated in thesame voice, rate or amplitude.These data suggest that, primeand target shared no common phonemes. In contrast,when prime eventhough voice, rate, and amplitude information may be encodeddif- andtarget shared phonemes but the phoneme positions were different, no ferently,information along all threedimensions is retainedin memory. facilitationof targetresponses was found.New studieshave further [Worksupported by NIH.] examinedthe segmental representation of speech using a newset of stimuli withboth naming and lexical decision tasks. While previous prime-target pairshave been either both nonwords or words,the new studies include word-nonwordand nonword-wordtrials. Additionally,the vowels in 5aSC7.Implicit memoryfor silent-centersyllables: Effects of talker, CVC primeand target were varied to examinethe influence of the vowel token, and delay, SusanL. Hura, LaurenE. Chascy,Joshua S. Kopf, similarityon primingwhen prime and target have consonants in common and Emily C. Muelhausen(Purdue Univ., Dept. Audiol. and Speech (e.g.,prime "eat," target "kit"). Resultswill bediscussed in termsof their Sciences,1353 Hearlion Hall, West Lafayette,IN 47907-1353} implicationsfor the natureof the abstract,segmental representation that underliesword recognition and lexical access. [Work supported by NIDCD Listeners'ability to reconstructmissing vowel informationin silent- Grant No. R01 DC00219 to SUNY at Buffalo.] center(SC} syllableshas been viewed as evidencethat vowelsare dynami- cally specifiedby the informationin syllabletransitions. In this study implicitmemory techniques are used to explorethe representations formed when listenersperceive SC syllables.A set of CVC words spokenby 5aSCA. Building lexical neighborhoods. Michael S. Vitevitch and severaltalkers was usedto createSC and full syllablestimuli. A subsetof PaulA. Lute (Dept.of Psych.,SUNY, Buffaio, NY 1426O-4110) SC stimuliwas presentedto listenersfor identification.After a variable delaylisteners were tested on the completeset of full syllables,some of The NeighborhoodActivation Model (NAM) statesthat the speed and whoseSC versionswere presented in theinitial phase. Other full syllables accuracyof spokenword recognition are a functionof the numberand overlapwith the SC set in termsof talkeror token.Performance on full natureof neighbors---orsimilar sounding words--activated in memoryby syllableswith differingdegrees of overlapbetween SC andfull stimuliis stimulusinput. In particular,the model states that spoken word recognition comparedacross a rangeof delays.Facilitation on full syllablestimuli is is a functionof (1) targetword frequency,(2) similarityneighborhood viewedas evidence that representations of individualSC stimuliare stored density,and (3) similarityneighborhood frequency. In a pretest-training in memoryand accessedin laterperception of full syllables. -posttestdesign, these three factors were manipulated using nonword tar- getwords and nonword neighbors to testdirectly predictions of NAM. The resultswere only partiallyconsistent with the model.As predicted,pro- cessingtimes to high-frequencytargets increased as a functionof neigh- 5aSCS. Perceiving the sex and identity of a sine-wave talker. borhooddensity. However, processing times for low-frequencytargets ac- JenniferM. Fellowes,Robert E. Remez (Dept. of Psych.,Barnard tually decreasedwith increasedneighborhood density. Furthermore, no College,3009 Broadway,New York, NY 10027-6598),and Philip E. significanteffects of neighborhoodfrequency were obtained. The implica- Rubin (HaskinsLabs., New Haven,CT 06511) tionsof thesefindings for NAM andother models of spokenword recog- nition are discussed. Listenerscan readily perceive both the linguisticmessage and the iden- tity of the talker from an utterancethat has been replicatedwith a few time-varyingsinusolds. One puzzlingoutcome of studiesof the identifi- cation of sine-wave talkers is that erroneous identifications did not cluster 5aSCS. The neighborhoodcharacteristics of malapropisms. Michael by sex.Males were often mistakenfor females,and vice versa.A seriesof S. Vitevitch (Dept.of Psych.,SUNY, Buffalo,NY 14260-4110) new experimentsused frequencytranspositions of sinusoidalreplicas of Thisstudy examined the neighborhood characteristics (frequency, den- speechto determinethe acousticattributes responsible for the identifica- sity,and neighborhood frequency) of 138 maiapropisms(whole word er- tion of a taiker'ssex and a talker'sidentity. The centralspectral tendency rors).A qualitativeanalysis suggests that wordsthat are moreoften in- of a sinusoidalsentence was found to affectthe perception of thesex of the volvedin malapropismshave low neighborhoodfrequencies. Additionally, talker; a sine-wavepattern derived from the formant frequenciesof an thesewords tend to be eitherhigh-frequency taxget words in denseneigh- individualtalker seemedmale, f•iA or nci:hcr...... tcansposedto borhoods,or low-frequencytarget words in sparseneighborhoods. Finally, matchthe male, female, or overall averageformant frequencies in our malapropismstended to occursuch that the word that was substitutedfor talker set,respectively. However, performance on a testof individualrec- the intendedword was more frequentthan the intendedword. The impli- ognitionwas very goodunder acoustic conditions that reducedsex deter- cationsof thesefindings for modelsof lexical representationand process- mination to chance levels. This suggeststhat recognizing a sine-wave ing are discussed. taikerdoes not dependon prioridentification of sex,and begins to explain why listenersare likely to confusesine-wave talkers without regard for the talker'ssex. [Work supportedby NIDCD.] 5aSC6. The effect of talker rate and amplitude variation on memory representationof spokenwords. Ann R. Bradlow (SpeechRes. Lab., Dept. of Psych.,Indiana Univ., Bloomington,IN 47405) and LynneC. 5aSC9. Talker variability effectson spokenword recall: Encoding or Nygaard (EmoryUniv., Atlanta, GA 30322) rehearsal? Meral Topeu, John W. Mullennix, Tina Bakalis, Mafia Stauch,and 'Dna Traceyski (Dept.of Psych.,Wayne State Univ., Detroit, This studyinvestigated the encodingof spokenword attributes in a task M1 48202) of continuousrecognition memory. In experiment 1, subjectswere pre- sentedwith a list of spokenwords, and for eachword theyjudged whether The effectsof talker variability were examinedfor spokenword recall. theword was "old" (hadoccurred previously in thelist) or "new."Results In thisstudy, a seriaiword recall paradigm was used, with talkervariability showedthat subjectswere moreaccurate at recognizinga word as "old" if manipulatedusing single- and multiple-talkerlists and with presentation it was repeatedin the samevoice (condition1), and at the samerate of rate variedusing fast and slow conditions.In addition,memory rehearsal 2588 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2588 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 processeswere examined via a continuousdistractor task. Under nu- 70-mssine-wave glides, which followed a similartrajectory to F2 in the distrectorconditions, the results showed that primacy recall performance speechstimuli, to 60-mssteady-state vowels varying in F2 frequency.A wasbetter for single-talkerlists compared to muhiple-talkerlists. Under secondset of nonspeechseries was created by appendingconstant- distractorconditions, when presentationrate was fast, this differencere- frequencysine-wave tones to the vowel stimuli.The frequencyof these mained.However, when presentationrate was slow, therewas little differ- toneswere set at the F2 startingfrequencies for the speechstimuli. These ence in recall for single-talkerversus muhiple-talker lists. Theseresults nonspeechcontexts had effects on vowel identificationthat were analogous will be discussedin termsof theroles of rehearsaland encoding processes to thosefor the speechcontexts. Lower frequencyglides and tones(mod- in the transferof voiceinformation to episodicmemory for spokenwords. eling/bVb/F2)led to more/œ/(higherF2) identificationswith thecomple- ['Worksupported by NIH GrantNo. DCO1667-03.] mentarypattern for higher frequency glides and tones. [Work supported by NIDCD and NSE] 5aSCI0. Learningvoices. LynneC. Nygaard (Dept.of Psych.,Emory Univ., Atlanta, GA 30322) and David B. Pisoni (Indiana Univ., 5aSC13. Identification of vowels based on visual cues within raw Bloomington,IN 47405) complexspeech waveforms. Michael A. Stokes (IndianaState Dept. of Health,P.O. Box 241153,Indianapolis, IN 46224) The presentexperiment was designedto investigatethe pemeptual learningof talker'svoice. Listeners were trainedover a 9-day periodto Testingwas performed to demonstratethat subjects can identify vowels becomefamiliar with a set of ten talkers (five male and five female). usingvisual displays of raw complexwaveforms. Two Midwesternmales Duringeach day of training,listeners were asked to identifytalkers' voices producednine vowels [Peterson and Barney, J. Acoust.Soc. Am. 24, 175- from isolated words and to associate each voice with a common name. On 184 (1952)] for two identificationtrials. In both trials, nine vowelswere the tenthday of testing,listeners were given a generalizationtest which presentedin randomorder by an experimenter.Subject MS correctlyiden- consistedof a setof novelwords produced by the ten talkersthey heardin tifiedfive out of ninevowels in bothtrials. Identification was accomplished trainingand by ten unfamiliartalkers (five male and five female). The by recognizingtemporal interactions between F0 and F1 that providecat- resultsshowed that over 9 days of training,talker identificationperfor- egoricalboundaries across the vowel space.The presenceor absenceof F2 manceimproved. However, there were large individualdifferences among in the range of 2000 Hz also providesa distinguishingcharacteristic be- listenersin talker learningperformance. In addition,individual differences tween categoricalpairs. When formant values and articulatorydata are in the identifiabilityof voiceswas observed.Male voiceswere identified organizedby categoriesseen within speechwaveforms, the vowel space significantlybetter than female voicesby both male and femaleslisteners. resemblesthe pairingsof the stopconsonants/b/-/p/,/d/-/tJ, and/g/-/kJ. The resultsof the generalizationtask showedthat the introductionof un- Tongueposition (reflected in F1 values)categorizes a vowel as placeof familiarvoices reduced identification performance for familiartalkers. Lis- articnlationcategorizes stop consonants. Lip position(reflected in F2 fre- tenerswere able to judge overall familiarity, but confusionsincreased in quency)distinguishes vowels within a categoryas voicingdistinguishes identificationof familiar talkers.The resultssuggest that talker-, listener-, theseconsonant pairs. The detailsand potentialsuccess of a new modelof andtask-specific factors influence the perceptual learning of talker'svoice. vowel perceptionbased on thesefindings will be discussed. 5aSCll. The effectsof multiple-talker stimuli on immediate memory 5aSC14. Enhancement of concurrent vowels: Postcursor effects and span. HelenaM. Saldafiaand William R. Svec (Dept.of Psych.,Indiana thresholds. D. Dwayne Paschall (Dept. of Commun.Disoral., Texas Univ., Bloomington,IN 47405) Tech Univ. Health SciencesCtr., Box 42073, Lubbock,TX 79409-2073) Previousexperiments revealed that changingthe voice between study Speechcommunication often takes place in noisy environments,in- itemson an auditorylist of lettersresults in a decreasein memoryspan [H. cluding situationswhere two or more voicescompete for the attentionof M. Saidaria,J. Acoust.Soc. Am. (1995)]. This findingis contraryto Bad- the listener.Experiments with simultaneousvowel pairs investigatedas- deley's articulatoryloop model which definesmemory span in terms of pects of a priming stimulusthat draws attentionto a target voice in a time or durationof items. According to this model items are stored as mixture of two voices.Previous studies have shownidentification accuracy memorytraces that fade after approximately2 s unlessrevived by an is higherin conditionswhere the vowel pair was precededby a precursor articulatorycontrol process [A.D. Baddeleyand G. J. Hitch, Psychol. with the same F 0 and spectrumenvelope as one of the vowels.These Learn.Motiv. (1974)].The numberof itemsthat can be reactivatedwithin findingsare consistentwith an explanationbased on auditoryadaptation. the decaytime can be retainedindefinitely. The presentstudy replicates This conclusionis reinforcedby resultsfrom the presentexperiments andextends the previousmemory span findings by utilizingdigits instead which showthat when the precursoris placedafter the concurrentvowel of lettersand by usinga stimulusmatching methodology for estimating pair (a postcursor),there is little benefitto identificationaccuracy. Thresh- spanlength. A reconceptualizationof the articulatoryloop model is dis- oldsfor identifyinga targetvowel in the presenceof a maskervowel when cussedwhich takes into account the encoding of stimulus variability. a precursoris presentwith the sameintensity, F0, and spectrumenvelope [Worksupported by NIH.] as the maskervowel suggeststhat the phenomenonof enhancementap- pearsconsistently only whenthe enhancedvowel and the precursorare at similar intensities.The presentexperiments suggest that enhancementis the resultof perceptualgrouping mechanisms that are supplementedby 5aSC12. Perceptual compensation for vowel undershoot may be adaptationprocesses possibly operating at a level more centralthan the explained by general perceptual principles. Lori L. Holt, Andrew J. auditorynerve. Lotto,and Keith R. Kluender (Dept.of Psych.,Univ. of Wisconsin,1202 W. JohnsonSt., Madison, WI 53706) When presenteda seriesof/dVd/syllables varyingperceptually from 5aSC15. Vowel perception in consonant context. Rachel Thorbum /dœd/to /dad/, listenersidentify the vowel soundas /M more often than (Linguist.Dept., Univ. of Massachusetts,Amherst, MA 01003) when the vowelsare presentedalone as steadystates. Conversely,/bVb/ serieslead to more/œ/identifications.This patternof responsesappears to Macmillan,Goldberg, and Braida [J. Acoust.Soc. Am. 84, 1262-1280 demonstratea compensationfor assimilatoryeffects of coarticulationor (1988)]show that when stimuli are presented along a continuum,instances vowel "undershoot."Experiments will be presentedwhich testthe speci- of consonantsthat are near good exemplarsare mostmemorable for la- ficityof thisperceptual process. Two ten-step(/bVb/and/dVd/) seriesof belingby a listener.However, for vowels(produced in isolation),instances 100-ms/CVC/ syllablesvarying in F2 midpointfrequency (1260-1710 whichare nearcategory boundaries are mostmemorable. Can theseresults Hz) were synthesized.Nonspeech analogs were created by appending be generalizedto vowelsproduced in context?What is the effectof dif- 2589 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society of America 2589 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 ferentconsonant contexts on vowel perception?To answerthese questions, cognitivepsychology, the model proposedhere builds on researchfrom this studytested high vowels along a front-backcontinuum produced in both psychologyand neuroscienceto accountfor the effect. This model two CVC contexts(labial or alveolar).The resultsshow that thesevowels embodiestwo principalhypotheses supported by considerableexperimen- producedin contextexhibit the patternsMacmillan et al. (1988) discov- tal and theoreticalresearch from the neuroscienceliterature: (1) Sensory ered for consonants,consistent with the idea that both vowels in context experienceguides development of an auditoryneural map, and (2) a popu- and consonantsare perceivedas linguisticentities, whereas isolated vow- lationvector analysis can predict psychological phenomena from mapcell els are not. The resultsalso show a differencein perceptionbetween the activities.These hypotheses are realizedin a sfinple,self-organizing neural two consonantcontexts. For vowels producedin the labial context,the network model. The magneteffect arisesin the model from language- boundarybetween front versus back perception was closer to thelul endof specificnonuniformities in the distributionof mapcell firingpreferences. the continuumthan for vowels producedin the alveolar context.This Thesenonunfformities result from exposureto language-specificdistribu- reflectscompensation by listenersfor theexpected effects of coarticulation with the flankingconsonants [Ohala and Feder,Phonetica 51, 111-118 tions of attendedsounds experienced by the networkduring training,in (1994); Bradlowand Kingston,I. Acoust.Soc. Am. Suppl. I 88, S56 keepingwith neurophysiologicalresults from auditory cortex [G. H. Re- (1990)].[Work supported by NIH GrantNo. 5-R29-DC01708.] canzone, C. E. Schreiner, and M. M. Merzenich, I. Neurosci. 13, 87-103 (1993)] and other sensoryareas. Numerical simulations verify that the modelcaptures the knowngeneral characteristics of the magneteffect and providesvery accuratefits to specificpsychophysical data. 5aSCI6. Vowel discrimination in a phonologically neutralized context. RobertAllen Fox andSon Tran (Dept.of Speechand Hearing Sci., Ohio State Univ., Columbus,OH 43210) 5aSC19. The phonoiogical relationship between Taiwanese initial The perceptionof vowel quality is not only affectedby the formant voiced stops and nasals. Ho-hsienPan (Dept. of Foreign Languages structureof the vowel, but by the nature of the surroundingphonetic andLiterature, Chiao Tung Univ., Hsinchu,30050, Taiwan) context.For example,it has beendemonstrated JR. A. Fox, in Speech Perception, Productionand Linguistic Structure, edited by Y. Tubkuts Taiwanesevoiced stops are followed by non-nasalizedvowels, while et al. {IOS Press,1992)] that listeners'ability to makereliable vowel nasalsare followedby nasalizedvowels. This studyuses a conceptforma- quality distinctionsare loweredwhen the vowelsare placedin a context tion paradigmto test whethernative speakers treat the voicedstops and that introducesphonological neutralization (e.g., post-vocalic[4]). One nasalsas allophonesor separatephonemes. There are threeexperiments in possibleexplanation for this phenomenonis thatof listenerbias, which the study.In the trainingsession of experimentA, monosyllabicmor- shouldbe eliminatedusing the appropriatesignal detectionmethodology. The presentstudy describes the resultsof an experimentthat obtainedd' pbemesare presented.Subjects receive a positivereinforcement when a measurementsof one-step differences in an [i]-[J]continuum in CV, CVr, syllablebeginning with/b/is presented.In the testsession of experiment CVI, and CVd contextsunder fixed-level,minimum uncertaintycondi- A, syllablesbeginning with/rrd are introduced.In experimentsB and C tions. Resultsdemonstrate after severaldays experiencewith the stimuli disyllabicphrases are presented.In the trainingsession of test B, the and methodologythat the discriminationdifferences as a functionof con- subjectsare reinforcedto treat/b/and/m/as separatecategories. In the text were eliminated. However, a post-trainingidentification test still trainingsession of testC, the subjectsare reinforcedto treat/b/and/m/as showedcontext effects on vowel categorization.These data will be dis- the samecategory. The resultsshow that Im,bl are groupedinto the same cussedin terms of the possiblenature of this listenerbias in vowel per- category.In experimentB, subjectscannot differentiate between/hi and ception. Ira/. In experimentC, when/b/and/m/are reinforcedto be of the same category,the subjectsperform well. Accordingto the interviewresponses after each test, subjectsdescribe the categorythat is being reinforced positivelyas nasals. 5aSC17. Temporal and acoustic parameters mediating perceptual overshootin vowel perception. John W. Hawks (Kent State Univ., Schoolof SpeechPathol. and Audiol., Kent, OH 44242) 5aSC20. Modeling processingdependences in speech perception. The experimentsreported here represent the preliminaryfindings of an Court S. Crowther (BoysTown Natl. Res. Hospital,555 N. 30th St., investigationdesigned to providea betterunderstanding of the parameters Omaha,NE 68131) underlyingperceptual overshoot in vowelperception. Continua of dynamic vocalic tokenswere synthesizedwhich spannedmultiple vowel categories andvaried in (1) F1, F2 locationof startingand ending points. (2) rateof The goal of this work was to determinewhether acoustic cues to the frequencychange, {3) directionof dynamictransition, and (4) totaldura- phoneticfeatures of a segmentare processedindependently. For stop- tion.Subjects delermined (1) whethereach token was heard as containing vowel(CV) syllables,one point of controversyconcerns whether place one or morethan one vowel quality,and (2) the identityof the vowel information(as conveyed by formanttransitions) and voicing information quality(s).The resultssuggest the values of thevaried parameters sufficient (asconveyed by VOT) areprocessed mutually independently. In this ex- for eliciting the overshootphenomenon and will be discussedin termsof periment,a replicationof Massaroand Oden [J. Acoust.Soc. Am. 67, evidencefor a purely auditorymechanism for overshootor whetheran 996-1013 (1980)], F2 and F3 transitionsand VOT were manipulatedas articulatory (Biomechanlcall Basiscan be considered. place and voicing cues in CVs. Members of a family of multinomial models,including FLMP, werefitted to eachsubject's data. FLMP, which assumesthat processingis independentat both the perceptualand deci- sional levels, failed to account for the data. Two other models retained the 5aSC18. The perceptual magnet effect as an emergent feature of neural map formation. FrankH. Guentherand Marin N. Gjaja (Dept. perceptualindependence assumption, but one assumedthe voicingdeci- of Cognit.and Neural Systems,Boston Univ., 677 BeaconSt., Boston,MA sionwas contingenton the outcomeof the placedecision, and the other 02215) assumedthe opposite contingency. Both fitted better than FLMP, but nev- erthelesswere rejected on statisticalgrounds. A modelassuming decisional The well-knownperceptual magnet effect [e.g., P. K. Kuhl, Percept. independence,but perceptual dependence, fitted each subject's data well. It Psychophys.50, 93-107 (1991)]is characterizedby a warpingof percep- was concludedthat the formanttransitions and VOT were not perceived tual spacenear phonemic category centers. Whereas previous explanations independently,but that the voicingand placedecisions were madeinde- of this effect have been formulated within the theoretical framework of pendently.[Work supported by NIDCD (2-T32-DC-00013-16).] 2590 d. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2590 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 5aSC21. Effects of amplitude on voicing contrast may not be elicitedaccurate tapping, indicating their treatment as second-syllableon- explainedby VIIIth nerve synchronycapture. AndrewJ. Lotto and sets,whereas taps to IVCs followinglax vowelswere early, indicating their KeithR. Kluender(Dept. of Psych.,Univ. of Wisconsin,1202 W. Johnson treatmentas first-syllablecodas. These results are consistent with linguistic St., Madison, WI 53706) theoryand explicit judgments of syllabification[see Trieman and Danis, J. Mem. Lang.27, 87-104 (1988)]. Kluender,Lotto, and Jenison[J. Acoust.Soc. Am, 97, 2552-2567 (1995)]reported that overall stimulus amplitude can affect perception of the voicingcontrast in syllable-initialstops. Their resultssupported an hypothesisthat a shift in the temporalpattern of neuralfiring from fre- quenciesnear F2 and F3 to FI andf0 could signalvoicelessness. The resultsof the currentstudy undermine this "synchronycapture hypoth- 5aSC24. First formant spectral properties and initial esis."The effectof amplitude(increased voice]ess identifications with stop-consonant[voice] judgments. MichelleR. Molls and RandyL. higheramplitude) maintains when there is no cutbackin FI duringthe Diehi (Dept.of Psych.,Univ. of Texas,Austin, TX 78712) quasiperiodicportion of the syllableand when stimuliare high-passfil- A low first formant(Fl) onsetfrequency is an acousticcorrelate of teredabove the frequencyof Fl. In a furthertest of the hypothesis,two [+voice]consonants. This is predictedby the "low-frequencyhypothesis" ten-stepseries (/baI-/paJ and /gaJ-/kaJ)were createdwhich maintained (LFH)--any increasein }ow-frequencyenergy near the consonantalclo- periodvoicing throughout the syllable(with FI cutbacksignaling voice- surewill enhancethe perception of [+voice] stopconsonants. In contrast, lessness).The energyjust below the frequencyof F2 and the energyabove Kluender,Lotto, andJenison [J. Acoust.Soc. Am. 97, 2552-2567 (1995)] F I were presenteddichotically. Thus, at the periphery,there was no com- proposedthat FI onsetfrequency acts as a cue via an indirecteffect on the petition betweenfrequencies near F2 and lower frequenciesand, as a temporalfiring patternof auditory-nervefibers. Following voice onset,the result,no chancefor a changein neural temporalpatterns. Subjects con- synchronousfiring of somemid- and high-CF fibersmay becomecaptured tinuedto label voicelessnessas a functionof overall amplitude.Alternative by energyin the regionof Fl. The degreeof capturegrows with decreased modelsof the encodingof voicelessnesswill be considered.[Work sup- FI/F2 distance.It can alsobe enhancedby increasingthe relative intensity portedby NIDCD andNSF.] of Fl. In caseswhere FI is moreintense, the LFH predictsmore [+voice] responsesbecause the absolute amount of low-frequencyenergy is greater; the "synchronycapture hypothesis" predicts fewer [+voice] responses becausesynchrony capture is morelikely as FI intensitygrows. In fact, 5aSC22. Auditory representationof changesin vocal dynamic level. manipulationof FI intensityproduced no changein subjects'responses ShadL. Campbell (Dept.ofCommun. Sci. and Disor&, Univ. of Georgia, indicatingthat neitherhypothesis is adequatein its presentformulation. Athens, GA 30602-7152) Evidencefor changesin synchronycapture is providedby two computer It is well knownthat changesin vocal dynamiclevel do not resultin a modelsof auditory-nervefunction. [Work supported by NIH.] simpleloudness increase. Rather, because the level of the higherharmonics tends to increasemore rapidly than that of lower harmonics,distinct changesin timbre typicallyaccompany the obviouschanges in loudness. 5aSC25. Preschoolchildren's use of dynamic acoustic information However, without referenceto auditory transformations,it is difficult to determinewhich of the observedspectral changes are preservedin the for word recognition. Benjamin Munson, Jan Edwards, and Robert "auditoryspectrum," or to estimatetheir perceptualeffects. In order to At]en Fox (Dept. of Speechand Hearing Sci., Ohio State Univ., Columbus,OH 43210) addressthese issues,sung vowels were recordedfrom several classical singers.Data representsix voice classifications,three vowels, three dy- While youngchildren's ability to usedynamic acoustic information to namic}eveIs, and threepoints within eachsinger's fundamental frequency categorizespeech sounds has beenstudied in somedetail [Nittrouer, J. range.Various unidimensional metrics based on modelsof auditorypro- Phon.20, 1-32 (1992)], relativelylittle is knownabout their ability to use cessessuch as frequencyselectivity, masking, loudness perception, and dynamicinformation for word recognition.This studyinvestigates whether timbreperception [Glasberg and Moore, Hear.Res. 47, 103-138 (1990); preschoolchildren could use dynamicacoustic information to identify Aures,Acustica 59, 130-141 (1985)] were obtained.Results to date indi- familiarwords with missingconsonants or vowels.A gatedseries [Elliot catethat the weightedfirst moments of the specificloudness and sharpness et al., Percept.Psychophys. 42, 150-157(1987)] was used to examine distributionsserve as promisingmeans of quantifyingchanges associated youngchildren's identification of familiarCVC wordswith missingfinal with changesin vocal dynamic level, and that these metricsare most consonants;similarly, a silentcenter series [Fox et al., J. SpeechHear. effective when derivedfrom excitationpatterns based on auditoryfilter Res. 35, 892-902 (1992)] was usedto examineidentification of CVC shapesrather than masking patterns. [Work supported by UGACOEFac- wordswith missingvowels. Eighteen typically developing children aged ultyResearch Grant.] threeto five were tested.It was foundthat even the youngestchildren did remarkablywell at recognizingwords with missingfinal consonants, even at the longestgate when the consonantwas deleted40 ms beforestop closure.By contrast,the childrenhad more difficulty with thesilent center 5aSC23. A novel psychophysicalprocedure for investigating the series,with somechildren being unable to performthe task.Results will be syllabic organization of phonemesin speech. JamesA. Bashford,Jr., presentedalso for a secondset of gatingand silentcenter tasks, in which RichardM Warren,and Bradley S. Brubaker (Psych.Dept., Univ. of a picture-pointingresponse, rather than a spokenresponse, was used. Wisconsin, Milwaukee, WI 53201) When listenersattempted to tap in synchronywith a targetphoneme in a repeatingphrase or sentence(e.g., "Most Wisconsin winters are cold."), tapsto syllable-initialphonemes were accurate,whereas taps to syllable- /I/in a stopcluster. LindaW. Norfix (Ctr.for Neurogenicand Commun. linal phonemeswere early.These results indicate that the apparentoccur- Disor&,Univ. of Arizona,Tucson, AZ 85721)and Kerry P. Green (Univ. renceof speechsounds depends upon syllabificafion, and thatthe synchro- of Arizona, Tucson,AZ 85721) nousphoneme-tapping task can be usedfor investigatingsyllabic structure. The tappingparadigm was usedto examine a topic of current interest--the Context effects in speechperception are thought to reflect knowledge syllabic assignmentof intervocalicconsonants. The stimuli were six about coarticulatoryinfluences from the surroundingphonetic environ- minimal-contrastpairs of bisyllabicCVCVC wordsdiffering only in their ment. This study investigatedif sucheffects occur when the contextis first vowels,having either a tenseVI (as in "tunic") or a lax VI (as in 5aSC26.specifiedAuditory-visualin the visualmodality contextand effects segmentalontheinformation perceptionin theof/r! auditoryand "tonic"). Tense-Vl andlax-V1 wordswere presented to separategroups of modality.In the firstexperiment, two continuawere synthesized: one vary- 24 listenerswho provideda sequenceof 15 tapsto eachtarget phoneme in ing from/iri-ili/and theother from/ibri-ibli/. Whenpresented to listeners therepeated words. lntervocalic consonants (IVCs) following tense vowels for identificationas/r/or/1/, therewas a significantshift in the category 2591 J. Acoust.Soc. Am., Vol.99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2591 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 boundarybetween the two continua.In a secondexperiment, the/iri-ili/ 3 and 4 years,listened to synthesizedconsonant-vowel syllables com- tokenswere pairedwith visual tokensof a talker saying/ibb`.When pre- prisedof all combinationsof [b d g] and[i]. The synthesisparameters sentedin anauditory-visual (AV) condition, these tokens were perceived as includedmanipulations of the followingstimulus variables: formant tran- rangingfrom/ihrb` to liblb'.Observers also identified the/iri-ilb' tokensin sition(moving or straight),noise burst (present or absent),and voicing a separateauditory-only (AO) condition.Results indicated a similarshift duration(10 or 46 ms).In a recentstudy [R. N. Ohdeet al., J.Acoust. Soc. in the/r-l/boundary betweenthe AO andAV conditions.Analysis of Ir/ Am. 97, 3800-3812(1995)] of childrenbetween 5 and11 yearsof age, and/1/productionsrevealed that the perceptualadjustments were consis- therewas no differencebetween children and adults in termsof the per- tent with the acousticconsequences of articulating/r/ and /1/ in a stop cluster.The findingssuggest that the perceptualadjustment reflects cross- ceptualweight placed on the dynamicformant transition cue. However,in modal knowledgeof the coarticulatoryeffects of a bilabial consonanton the currentstudy, preliminary findings indicate that youngchildren's iden- the acousticrealization of/rl and/1/.[Work supported by NIDCD, Nilfl.] tification of stop consonantswas higher for moving transitionsthan straighttransitions. In addition,the children'sidentification of stopswas frequentlypoor in the[i] context.Overall, these results suggest that chil- drenpay particularattention to dynamiccues in the earlyperiod of sound 5aSC27.A reconsiderationof intensity-basedduplex perceptionfor acquisition,and that they havereduced auditory sensitivity for acoustic speech. MichaelD. Hall and PatriciaK. Kuhl (Dept. of Speechand correlatesof placeof articulationin the[i] context.[Work supported by Hear. Sci., CHDD, Box 357920, Univ. of Washington,Seattle, WA mIDeD.] 98195-7920) Duplexperception (DP) occurswhen one stimulus component simul- taneouslycontributes to two distinctpercepts. In onepotential demonstra- 5aSC30.Age-related changes in the categoricalperception of stop tion,a sinusoidalglide is substitutedfor an F3 transitionin a/da/or/ga/ consonants.Elzbieta B. Slawinski (Dept.of Psych.,Univ. of Calgary, syllable,and the glide is claimedto distinguishthe consonant while simul- 2500 UniversityDr., Calgary,AB T2N 1N4, Canada) taneouslybeing separately perceived as a nonspeechchirp. Recentcon- cernsregarding the validity of evidencefor this variant of DP were ad- dressedusing theoretically bias-free psychophysical methods. Individual The studyfocused on changesin the categoricalperception of intial thresholdsfor consonant,and chirp, perception were compared as a func- stopconsonants as a functionof ageand hearing status. The identification tion of glide intensity.Consistent with DP, consonantidentification and of intialstop consonants differing in voicingand place of articulationrelies discriminationwere maintained at glideintensities well belowchirp de- on an integrationof multipleacoustic cues (VOT, characterof the noise tectionthreshold. Listeners also could not reliably match isolated glides to burst,onset frequency and directionof the secondand third formanttran- glidesin speechcontext, indicating that consonants were not simplyin- sitions).Four hundred subjects, divided into four age groups (20-85 years) ferredfrom the perception of isolatedglides. Methodological implications andinto three hearing groups, participated in experiments that required the of the resultsare discussed,including the needto insurethat the natureof identificationof syllables [ba] or [pa]and [ba], [da], or [ga]along synthe- consonantperception depends upon the mixtureof a given glide with the sizedcontinua. Stimuli were presented to subjectsvia headphones at 75 dB remainderof the syllable.An alternative,and potentiallymore reliable SPL. Resultsdemonstrated that the phonemicboundary of the [ba-pa] methodfor evaluatingchirp detectionthreshold also is provided.[Work supportedby NIH.] continuumwas shifted towards a longerVOT as a functionof ageand hearingstatus. Moreover, the phonemic boundaries between [ba] and[da], andbetween [da] and [ga], demonstrated by older and hearing impaired subjectswere shifted toward [d] and[g] categoriesascompared to young 5aSC28.Individual differences and the perception-productionlink. subjectswith normalhearing. The observedchanges may be dueto the RochelleS. Newman (Dept.of Psych.,Park Hall, SUNY, Buffalo,NY age-relateddeterioration of abilityto analyzebrief signals and ability to 14260) integratemultiple acoustical cues. [Work supported by Health and Welfare of Canada.] Severaltheories (e.g., Motor Theory [Liberman and Mattingly, Cogni- tion21, 1- 36, 1985])posit a linkbetween perception and production. One wayof examiningthe interrelationship between production and pereeption is to lookat individualdifferences in bothtypes of tasks.Previous research 5aSC31. An age-basedaudltory Stroop effect. JamesV. Ralston, hasyielded somewhat ambiguous results, but manyof thesestudies looked JaradM. Plesser(Dept. of Psych.,Ithaca College, 1119 Williams Hall, at the boundariesbetween categories. The currentstudy examined indi- Ithaca,NY 14850),and Elizabeth A. Lawless(Ithaca College, Ithaca, NY viduals'prototypes and related data from production. Subjects participated 14850) in a pereeptualtask modeled on thatof Miller andVolaitis [Percept. Psy- chophys.46, 505-512 1989].Subjects heard members of a VOT series centeredon /pal and ratedthem accordingto "p" categorygoodness. The presentresearch investigates the effectof semanticcontent of an Thesesame subjects were recorded producing stop consonant-vowel to- utteranceon ageperception. On eachtrial of two experiments,listeners kens,and the VOTs of theseproductions were measured. A correlationwas heardeither a relativelyold or youngvoice uttering a wordor nonword. foundbetween the average VOT for subjects'productions of "pa" andthe Listenersrapidly decided whether the speaker was relatively young or old. VOT of thetokens they rated as the best examples. This supports the idea Oneexperiment included five repetitions of thewords "young" and "old," of a perception-productionlink. and leavesopen the possibilitythat a anda nonwordgpokan by a collage-agedand a middleaged female. Analy commonmechanism may be usedin bothprocesses. [Work supported by sesof reactiontimes for correctresponses revealed a Stroopeffect: Re- NIDCD GrantNo. R01 DC00219 to SUNY at Buffalo.] sponseswere quicker when the semanticinformation and the ageof the speakerwere consistent than when they were inconsistent. Overall reaction times,but not the Stroopeffect, decreased across repetitions. A second experimentutilized the words"young" and "old," age-associates,age- 5aSC29.Stop consonantperception in 3- and 4-year-oldchildren. RalphN. Ohdeand Katarina L. Haley (Div. of Hearingand Speech neutralwords, and nonwords, all recordedfrom a college-agedand a Sciences,Station 17, VanderbiltUniv. Schoolof Medicine,Nashville, TN middle-agedfemale. Analyses of reactiontimes revealed a Stroop effect 37232) for thesemantic associates. In addition, there was a strongtrend for re- sponsetimes for nonwordsto be greaterthan those for neutralwords. The The purposeof this studywas to examinethe importanceof different combined resultsdemonstrate that lexical information influencesa listen- acousticproperties for theperception of placeof articulationin young er's perceptionof age.Results from more recent studies manipulating childrenand adults. Ten adults and ten children in bothof theage groups, listenerset will alsobe presented. 2592 d.Acoust. Soc. Am., Vol. 99, No. 4, Pt.2, April 1996 131stMeeting: Acoustical Society ofAmerica 2592 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 5aSC32.Dynamic cues in vowel identification:A training study. cues for vowel identification. Sine-wave stimuli consisted of two tones Amy T. Neeland Diane Kewley-Port (Dept. of Speechand Hearing representingFI andF2 from 10 vowelsproduced by a femalespeaker. Sciences.Indiana Univ., Bloomington, lN 47405) Fourtypes of stimuliwere constructed by varyingtwo factors: (1) dynamic The importanceof dynamicformant information for vowel identifica- versusstatic formants and (2) appropriateversus fixed vowel duration. tionhas been shown by severalstudies in recentyears. Using sine-wave Listeners were trained to criterion on one set of stimuli and were tested on vowelanalogs, Neel andKewley-Por• [J. Acoust.Soc. Am. 96, 3284(A) another.Training significantly improved identification accuracy. In com- {199411demonstrated that vowel duration is an importantcue for vowel parisonto performanceon staticformant tokens, listeners were more ac- identity and that dynamic formant informationis more efibctive when curate in identificationand improvedmore from baselineto test when duration cues are absent. However, because identification rates for sine- dynamic formantcues were present.Listeners also showedan identifica- wave stimuli were low, a trainingstudy was conductedto determinethe tionadvantage when duration cues were available. [Research supported by impactof trainingon the effectivenessof dynamicformant and duration NIHDCD ResearchGrant No. DC-02229.] FRIDAY AFTERNOON, 17 MAY 1996 REGENCY C, 1:15 TO 4:45 P.M. Session5pPA PhysicalAcoustics: Resonant Ultrasound SpectroscopyII Hassell M. Ledbetter, Chair NationalInstitute of StandardsTechnology, Materials Reliability Division, 325 Broadwa);Boulder, Colorado 80303 Invited Papers 1:15 5pPAI. Unusual elasticproperties of pure and doped La2CuO4 as probed by resonantultrasound spectroscopy. John L. Sarrao,Z. Fisk (NationalHigh MagneticField Lab., 1800E. PaulDirac Dr.. Tallahassee,FL 32306),T. Darling,and A. Migliori (Los Alamos Natl. Lab.. Los Alamos, NM) LazCuO4 undergoesa structuralphase transition from tetragonalto orthorhombiccrystal symmetry as it is cooledbelow 525 K. Hole-dopingthe material{for example.by substitutingSr for La or Li for Cu) rapidlysuppresses the structuraltransition temperature. Additionally,the in-plane lattice constant of La• ,Sr,Cu•_yLi•O4isa functiononly of thecombined hole count (i.e., x+y) andnot of the individualSr and Li concentrations.RUS measurementsfor stoichiometric,St-doped, and Li-doped La•_CuO 4 have been used not only to map out the phasediagram of this systembut also to revealthe unconventionalnature of the transition.These results suggesta strongcoupling between hole concentration and structural properties as well as a largein-plane/out-of-plane anisotropy. 1:45 5pPA2.Cracks in steelrollers: Detection using resonant ultrasound spectroscopy. Ming Lei (Quatrosonics.Inc., 4209 Balloon Rd. NE. Albuquerque,NM 87109) A resonantultrasound technique has been applied to detectcracks in steelspherical rollers. Combining theoretical calculations with RUS measurements,steel rollers provided by a commercialsource with variousdimensions and aspect ratios were studied. As a result, correlationsbetween aspect ratio and deformationtype for someresonant modes were established. Empirical relationships between somespecific modes and dimensions were also obtained, with whichresonant frequencies of torsional,disk bending, and cylinder bendingmodes can be predictedfrom dimensionsof the rollersfor variousaspect ratios. Hence, the testingfrequency ranges for a given roller can be determineddepending on the type of defectsthat needto be detected. 2:15 5pPA3. An investigationof computational problems associatedwith resonant ultrasound spectroscopy. P.S. Spoor,P. J. White,and J. D. Maynard (Dept.of Phys.,Penn State Univ., OniversityPark. PA 16802) At a previousmeeting (June 1995) a reportwas given on anomalousbehavior of the Rayleigh-Ritzmethod for calculatingthe normalmode frequencies of elasticsolids (the method that forms the basis for mostresonant ultrasound work). when those solids had theshapes of slightlyperturbed parallelepipeds. These shapes are of interestto understandthe effectsof samplepreparation errors on the overall elasticconstant determination. in an effort to understandthese effects. a systematicstudy of the variousinterrelated computationalissues in RUS hasbeen undertaken. Attempts are madeto addressthe followingissues: (!) whetherthe anomalous behaviorof the Rayleigh-Ritzsolutions is algorithmicor numerical;(2) whetherthese anomalies may result from problems with the inversecalculation (where the frequencies are inverted to obtain elastic constants) as well; and (3) whatrelationship exists between the RMS errorin the frequenciesand the confidencein the elasticconstant determination. Results will be showncomparing analyses of actualdata with and without the inclusionof a correctionfor nonparallelisrrdnonporpendlaularityin thesample. [13)'ork was supported in partby theOffice of NavalResearch.] 2:45-3:00 Break 2593 J. Acoust. Soc. Am., VoL 99, No. 4, Pt. 2, April 1996 131sl Meeting:Acoustical Society of America 2593 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 Contributed Papers 3:45 5pPA4.Scattering pole resonances:Relation to externaland internal 5pPA7. Resonantultrasound in circular pipes. Fred M. Mueller, surfacewaves. H. 0befall (Phys.Dept., Catholic Univ., Washington, DipenN. Sinha,Roger D. Hasse,and Kendall N. Springer(Los Alamos DC 20064, LAUE, Univ. of Le Havre, 76610 Le Havre. France, and Nat. Lab., Los Alamos, NM 87545) CNRS, Lab. M6caniqueet Acoust., 13402 Marseilles,France), J. Duelos.M. El HocineKbelil, G. Maze, J. Ripocbe (Univ. of Le Havre, Resonantultrasound has found multiple applications,ranging from 76610Le Havre,France), A. G6rard (Univ.of Bordeaux,33405 Talenee, medicalimaging to a varietyof nondestructivetesting techniques. Here France),X. L. Bao, P. K. Raju (AuburnUniv., Auburn,AL 36849),1. focusis placedon nestedcylinders. A seriesof ultrasonicmeasurements P. Sessamgo,and J. Sageloll (CNRS, 13402Marseilles, France) hasbeen carried out in a geometrywith an outerhollow steelcylinder, and a smaller,solid innersteel cylinder. In the interspacewere placedseveral The resonancescattering theory and the singularityexpansion method liquids.Ultrasound was introduced by a narrowcontact transducer. A sec- are basedon the complex-frequencypoles of the scatteringamplitude; ond set of narrowtransducers was usedas pickupsand placedat angles theseare locatedoff the real-frequencyaxis and lead to prominentreso- rangingfrom 10 to 150deg. The frequencyof the ultrasoundwas varied nances.Their physicalorigin lies in a phasematching of surfacewaves from I to 5 MHz and showeda sequenceof eight compositeand sharp generatedon the scatteringobject; hence a studyof the resonanceswill resonancesspaced at about0.5 MHz. The compositeresonances showed a lead to information on these surface waves. This will be demonstrated here stronglyskewed behavior as a functionof frequency.The velocitypotential for immersedelastic objects of plane,spherical, and cylindrical geometry hasbeen modeled by usingcombinations of Hankelfunctions of complex whereeven the physicalnature (fluidborne or elastictype} of the surface argument.Convergence was achievedby usingangular m's up to 150. wavescan be identifiedalong portionsof their dispersioncurves, and These showedthat the asymmetryof the compositeresonance peaks is wherefor multilayeredstructures individual-layer resonances can be dis- primarilya phaseor geometricaloptics effect. tinguished,leading to solutionsof the correspondinginverse problem. 4:00 5pPA8. Free vibrations of LiNbO s piezoelectriccrystals. Martin L. 3:15 Dunn (Dept. of Mech. Eng., Univ. of Colorado, Boulder, CO 80309-0427),Hassel Ledbetter (NationalInst. of Standardsand Technol., 5pPAS.Radiation impedance of RUS modesin fusedsilica and KCI. Boulder,CO 80303), and Paul Heyliger (ColoradoState Univ., Fort J. Herro,H. Zhang,C. Hucho,D. Beck,M. Levy (Dept.of Phys.,Univ. Collins, CO 80523) of Wisconsin, 1900 E. Kenwood Blvd., Milwaukee, WI 53211), D. Isaak,$. D. Cames,and O. Anderson (UCLA, Los Angeles,CA) The first stepstoward measuring the elasticand piezoelectricconstants of piezoelectricsolids using resonant ultrasound spectroscopy (RUS) have The pressuredependence of the resonancefrequency of severalRUS beenundertaken. Specifically, free-vibration frequencies of a piezoelectric modesin samplesof fusedsilica and KCI hasbeen measured at UCLA in LiNbO3 crystalwere measuredup to 1 MHz. The vibrationfrequencies of atmospheresof air, He, and Ar nearambient temperature. For bothcom- the piezoelectricparallelepiped were alsopredicted using the finiteelement pressionaland torsionalmodes the radiationresistance appears to be lin- methodwith publishedvalues of the elastic,piezoelectric, and dielectric earlydependent upon pressure and increaseswith the molecularmass of constantsof LiNbOs. Publishedvalues of theseconstants from different the surroundinggas. The effectsare largerfor breathingmodes than for sourcesusing different methods are in masonablygood agreement.They torsionalmodes. A modelwill be presentedwhich will attemptto fit some alsoagree well with measurementsof someof the constantsperformed in of thesedata both qualitatively and quantitatively. [Work supported by the this studyusing a pulse-echotechnique. Predicted piezoelectric vibration Officeof Naval Research.] frequenciesagree well with measuredfrequencies. Predictions from an elasticvibration analysis underestimate those from a piezoelectricvibra- tion analysisby up to 12%. The resultspresented here suggestthe feasi- bility of developingan inversionmethod to extractboth the elasticand piezoelectricconstants. This would extendthe studyof Ohno [I. Ohno, 3:30 Phys.Chem. Minerals 17, 371-378 (1990)] who usedRUS to determine 5pPA6. Electromagneticexcitation and acousticspectroscopy of the the elasticconstants of alpha quartz.The piezoelectriceffect was consid- quadrupole elastic mode of an empty nearly spherical shell. Brian ered,but no attemptwas madeto determinethe piezoelectricconstants as T. Hornerand Philip L. Marston (Phys.Dept., WashingtonState Univ., they were held fixed duringthe inversionto obtainthe elasticconstants. Pullman,WA 99164-2814) The lowestquadrupole mode of an emptynearly spherical metallic 4:15 shell was excitedby a novelform of EMAT (electromagneticacoustic transducer)not havingmechanical contact with the shell.An oscillating 5pPA9. The inherent backgroundin acousticwave scatteringby a currentis suppliedto a coil locatednear the equatorof the ghell.The ghell submerged target. Myoung Soon Choi, Young Sang Joo, and Jong Po vibratesin responseto the Maxwell stresseswhich are distributedover the Lee (Nondestruct.Eval. Team, Korea Atomic Energy Res. Inst., P.O. Box shelfs surfacein a way especiallyfavorable for excitationof the lowest 105, Yusong,Taejon 305-600, Korea) quadrupolemode (a bendingmode) which has a naturalfrequency near 64 kHz. The stressesare associatedwith the Lorentz forceson eddy currents A new conceptfor the backgroundin resonancescattering of acoustic aroundthe equator.The mode is detectedwith a small microphoneplaced wavesby a submergedtarget is proposed.The idea is that the remainder near the shell. In one versionof the experimenta large de bias magnetic after removingonly the resonancesfrom the targetresponse must be used field is superposedon a weakeroscillating field of frequencynear 64 kHz. as the background.The complexwave numberswhose imaginary parts are In another version of the experimentthe bias field is removed and the the attenuationcoefficients of elasticbulk wavesin targetare introducedto frequencyof the oscillatingfield is near32 kHz (half of the excitedme- dampout the resonances.From the assumptionthat the structuraldamping chanicalfrequency). The methodmay haveapplications to the inferenceof coefficient, the product of the attenuationcoefficients of elastic bulk the contentsor elasticproperties of shellsand to the investigationof the waves,and the outerradius of target,is a largeconstant compared with the modalstructure of openshells. [Work supportedby the Officeof Naval radiationdamping coefficients of resonances,a simple mathematicalex- Research.] pressionis derived for elasticcylindrical shells and namedthe inherent 2594 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society of America 2594 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 background.It is shownthat the inherentbackground leads to the impen- men symmetry,resonance ultrasound spectrosopy can determinethe full etrable(i.e., rigid or soft)background in somelimiting cases and also elasticstiffness tensor to greatprecision with one measurement. This mea- describesexactly the backgroundof elasticshell over entire frequencies surementis fast, takingless than a minutewith state-of-the-aninstrumen- regardlessof shellthickness. tation,making it appropriatefor measuringproperties as a functionof temperature.Parts per million changes in specimendensity, geometry, elas- 4:30 tic moduli,temperature, and boundary conditions can be detectedin carbon fiber reinforcedepoxy compositematerials with resonanceultrasound 5pPAI0. RUS investigationof the anisotropicelastic propertiesof spectroscopy.It is importantto know the mechanicalproperties of carbon GFRP compositesat low temperatures. Timothy M. Whitney and fiber reinforcedepoxy compositematerials at low temperaturesfor under- RobertE. Green,Jr. (Ctr. for Nondestmct.Eval., JohnsHopkins Univ., water, space,and polar applications.The amplitude/frequencyresonance Baltimore, MD 21218) spectraof four different lay-ups of AS4/3501-6 carbon fiber reinforced The resonancespectrum of any specimenis dependenton its symme- epoxy compositehave been measuredat I øC intervalsfrom - 177 øC to try, density,geometry, elastic properties, and the boundaryconditions. By 25 øC. The spectraindicate increasing stiffness and decreasingdamping usingspecimens with simpleknown geometry and models including speci- with decreasingtemperature. FRIDAY AFTERNOON, 17 MAY 1996 MT. RAINIER AND MT. MCKINLEY, 1:00 TO 4:00 P.M. Session5pPP Psychologicaland PhysiologicalAcoustics: Auditory Localization and Pattern Perception(Poster Session) Robert A. Lutfi, Chair Departmentof CommunicativeDisorders, Waisman Center, University of Wisconsin,1500 Highland Avenue, Madison, Wisconsin 53705 ContributedPapers All posterswill be on displayfrom 1:00 to 4:00 p.m. To allow contributorsan opportunityto see other posters,contributors of odd-numberedpapers will be at their postersfrom 1:00 to 2:30 p.m. and contributorsof even-numberedpapers will be at their posters from 2:30 to 4:00 p.m. 5pPP1. The masking-leveldifference in low-noisenoise. JosephW. yearsof age had adult-likeMLDs for all BWs •> 40 Hz. The youngest Hall Ill, John H. Grose (Div. Otolaryngol.,Univ. North Carolinaat children did not reach adult levels until BWs >• 320 Hz. To determine ChapelHill, ChapelHill, NC 27599-7070),and William M. Hartmann whetherthe smallerMLDs at narrowBWs were due to the perceptual (MichiganState Univ., EastLansing, MI 48824) similaritybetween the maskerand the signal,MLDs were alsomeasured in conditionswhere both masker and signal had BWs = 20 or 320 Hz. The masking-leveldifference for a 500-Hz pure tone signal was ex- Children under 8 yearsof age showedthe sameMLDs for both BWs. amined for an interaurallyin-phase noise having different degreesof Olderchildren and adults had larger MLDs for thenarrow BW. [Thiswork powerfluctuations. MLDs were reliablysmaller in noisehaving relatively supportedby NIH NIDCD.] low power fluctuations.This effect was due to the following trendsin the thresholddata. (1) For all subjects,the So thresholdimproved as the degreeof noise fluctuationdecreased. (2) For some subjects,the S• thresholdworsened as the degreeof noisefluctuation decreased. (3) For 5pPP3. Benefit of binaural hearing in a multi-source environment. I. somesubjects, the S• thresholdstayed constant as the degreeof noise Sound localization. Ruth Y. Litovsky,Monica L. Hawley, JenniferK. fluctuation decreased. These results are discussed in terms of comodulation Jones,Leah B. Dunton,and H. StevenColburn (Dept. of BiomedicalEng. maskingrelease and the relevanceof envelopecues for the MLD. [Work and Hearing Res. Ctr., Boston Univ., 44 CummingtonSt., Boston,MA supportedby AFOSR.] 02215) A multi-sourcelistening environment was simulatedunder headphones by recordingsignals through KEMAR in a sound-deadenedroom. Seven 5pPP2. The masking level difference in children: Effects of signal loudspeakerswere each positionedin the frontal plane 5 ft from KEMAR and masker bandwidths. John H. Grose, JosephW. Hall III, and at 30-degincrements, ranging from +90 (right)to -90 (left).The recorded Madhu Dev (Div. Otolaryngol./Head& Neck Surgery,Univ. North signals(IEEE Harvardsentences) were digitallymixed and playedback Carolina,Chapel Hill, NC 27599-7070) underheadphones in a sound-proofbooth using a Digital Audio Tape Theage at which the magnitude of themasking level difference (MLD) (DAT) player.Sound 1ocazation accuracy was measured for "target"sen- reachesadult levels depends partly upon masker bandwidth (BW). For tencein the presenceof various"jammers." Three variables were manipu- wider BWs, childrenperform like adultsby 5-6 yearsof age. For narrow lated. First, the numberof "jammers" was either none, one, two or three. BWs, adult-likeperformance is not reacheduntil an olderage. To examine Second,the relative locationof the targetsand jammers was varied, such this age dependencefurther, this study measuredthe MLD for a 500-Hz that they were either in close proximity, widely separated,or someof each. tone as a functionof maskerBW in a group of 20 children aged 5-10 Third, the jammer content comprisedof either other sentences,speech- years,and in a groupof 10 adults.Masker BWs were 20, 40, 80, 160, 320, shapednoise, babble or time-reversedsentences. Normal-hearing listeners and 1000 Hz, centeredat 500 Hz. The MLDs of the childrenwere gener- were tested under binaural and monaural conditions. The content of the ally smaller than thoseof the adultsfor BW = 20 Hz. Children over 7 targetsentence was known. Localization accuracy decreased as the number 2595 J. Acoust. Soc. Am., Vol. 99, No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society of America 2595 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 jammersincreased, and as the proximityof the targetand jammers was termincif the failure to find a simplerelation might he due to differences increased.In addition,performance was worseunder mortaural than under in the typesof cues mediatingthese thresholds. The soundof a source binauralconditions. [Work supported by NIH DC02696,DC00100-21.] moving in a straight path on the azimuthal plane was synthesizedover headphonesto includethree dynamiccues for motion:Doppler shift, in- tensity,and interauraldelay. The threecues were perturbedslightly from trial to trial so that correlationswith listener responsescould be used to 5pPP4. Benefit of binaural hearing in a multi-sourceenvironment. estimatethe relative weight given to each cue.A 2IFC procedurewas used lI. Speechintelligibility. Monica L. Hawley, Ruth Y. Litovsky,Leah to measuredifferential thresholds for displacement,velocity, and accelera- B. Dunton, JenniferK. Jones,and H. Steven Colbum (Dept. of tion of four listeners.For the discriminationof displacement,responses BiomedicalEng. and Hearing Res. Ctr., Boston Univ., 44 CummingtonSt., were mosthighly correlatedwith intensityor interauraldelay, but for the Boston,MA 02215) discriminationof velocity and acceleration,responses were most highly correlatedwith Doppler shift. The resultsprovide a meansof accounting A multi-sourcelistening environment was simulatedunder headphones for differencesin sensitivityto motion that cannotbe inferredfrom sensi- by recordingsignals through KEMAR in a sound-deadenedroom. Seven tivity to displacementalone. [Researchsupported by NIDCD R01 loudspeakerswere eachpositioned in the frontalplane 5 ft from KEMAR DC01262-04.] at 30-degincrements, ranging from +90 (right)to -90 (left).The recorded signals(IEEE Harvardsentences) were digitally mixedand playedback under headphonesin a sound-proofbooth usinga Digital Audio Tape (DAT) player.Speech intelligibility was measured for a "target"sentence 5pPP7. Auditory localization aftereffects. Makio Kashino and in the presenceof various"jammers." Three variableswere manipulated. Shin'yaNishida (NTT BasicRes. Labs.,3-1, MorinosatoWakamiya, First, the numberof "jammers"was eithernone, one, two, or three.Sec- Atsugi, Kanagawa,243-01 Japan) ond, the relativelocation of the targetsand jammers was varied,such that they were either in close proximity, widely separated,or some of each. It was observedthat the perceptuallateralization of a sound(test) Third, the jammer contentcomprised of either other sentences,speech- havingan interauraltime difference(ITD) is shiftedaway from that of a shapednoise, babble or time-reversedsentences. Normal-hearing listeners were tested under binaural and monaural conditions. On each trial the priorsound (adapter) having a differentITD. First,the frequencyselectiv- locationof the targetsentence was known, and the percentageof key ity of this "auditory lateralizationaftereffect" was examinedfor sinusolds wordscorrectly identified is reported.Speech intelligibility was degraded presentedthrough headphones, with variouscombinations of adapterand as the numberof jammersand as the targetproximity to thejammers was test frequenciesbelow 800 Hz, usingthe methodof constantstimuli. The increased.[Work supported by NIH DC02696,DC00100-21.] magnitudeof the aftereffectwas foundto be largestwhen the frequencies of the two soundswere similar. It decreasedas the frequencydifference increased,and virtuallydisappeared at a frequencydifference of one-half octave.Second, the ITD selectivityof the aftereffectwas examinedfor 5pPP5. The fidelity of virtual auditory, displays. Payel Zahorik, 400-Hz tones.Subjects' judgments of lateralizationwere measureddirectly FredericL. Wightman (Dept. of Psych.and WaismanCtr., Univ. of in termqof the azimuthof the test signalfor variouscombinations of Wisconsin, Madison, WI 53705), and Doris J. Kistler (Univ. of adapter and test ITDs in the range of ñ 625 /•s. It was found that the Wisconsin,Madison, WI 53705) magnitudeof the aftereffectwas rather small when the ITDs of theadapter and testsignal were similar,and was largestwhen ITDs differedby 250 or A new method for on-line virtual sound source synthesishas been 375/•s. Theseresults will be discussedin termsof implicationsfor theo- developedthat affords direct comparison of virtualand real soundsources. riesof binauralinteraction, possible neural sites, and functionalroles of the Usingthis method, four listenersperformed a 2AFC discriminationof real effects. free-field sourcesand the virtual representationsof these sources.The sourcesconsisted of widebandnoise bursts presented at a numberof spatial positions.Virtual source fidelity was manipulated (on a trial by trial basis) by applyingwindows of variouslengths (20.48, 5.12, 1.28,0.32 ms)to the 5pPP8. One, two, many--Judging the number of concurrent talkers. impulseresponses (20.48 ms in duration)of the filtersused to synthesize Makio Kashinoand TatsuyaHirahara (NTT Basic Res. Labs., 3-1, the virtual sources.When fidelity was highest,listeners could not discrimi- MorinosatoWakamiya, Atsugi, Kanagawa, 243-01 Japan) nate virtual from real sound sources.As window length was decreased, diseriminahilityincreased. For a 1.28-mswindow, performance was above The ability of listenersto judge the numberof concurrenttalkers was 75% correcton average.These results are consistentwith physicalmea- examined.Ten female and 11 male Japanesetalkers each recorded20 surementsof the differencesin the acousticsignal at the listener'sear drum familiar Japanesewords consisting of four consonant-vowelsyllables betweenvirtual and real sourcepresentation. In a relatedexperiment, the each.In eachtrial, a numberof differenttalkers was chosen randomly from samefour listenerswhere asked to reportthe apparentpositions of the the same-sexgroup, and presentedsynchronously to four nativeJapanese virtualsound sources synthesized in the previousexperiment. Degradation listeners.who were askedto judge how many talkerswere present.The in localization performance was observed as filler window length was rangeof talker numberswas unknownto the listeners.To eliminatecues decreased.[Work supported by NASA.] associatedwith level, the over-all soundpressure level was varied ran- domly in each trial, with RMS levels of the individualwords equalized. It was foundthat judgments were nearlyperfect for up to two talkers,but $pPP6. Correlational analysisof acousticcues for the discrimination deterioratedabruptly for threeor moretalkers. In the lattercase, the num- of auditory motion. Wen Wang and RobertA. Lutfi (Psych.Dept., ber of talkerswas underestimated, although estimates increased slightly as Univ. of Wisconsin, Madison, WI 53706) the numberof talkersincreased. Factors that may promotesound source separation,such as lexicality(e.g., forwardversus reverse speech) and Previously,it wasreported that differentialauditory thresholds for ve- spatialseparation (e.g., single versus multiple loudspeakers), did notaffect locityand accelerationdo not appearsimply related to thresholdsfor dis- performance.Understanding a messagein the presenceof other voices placementusing synthesiz•l sound sources [Wang and Lutfi, J. Acoust. may be differentfrom the judgmentof numberof talkers;the former Soc.Am. 95, 2897(A)(1994)]. The presentstudy was undertaken to de- requiresonly the separationinto two entities---oneand the others. 2596 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, Apdl1996 131stMeeting: Acoustical Society of America 2596 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 5pPP9. Effect of the number of distracting streams on the focusing 5pPPI2. Effects of musician's earplugs and protective headgear on of attention on one auditory stream. Renaud Brochard,Carolyn localization ability in the horizontal plane. Nancy L. Vause and D. Drake, SteveMcAdams, and Marie-ClaireBotte (Lab. of Exp. Psych., WesleyGrantham (Div. of Hearingand Speech Sciences, Vanderbilt Univ. CNRS URA 316, 28 rue Serpente,75006 Paris,France) School of Medicine, and Bill Wilkerson Ctr., 1114 19th Ave. S., Nashville, TN 37212) The experimentreported here dealswith the conditionsunder which listenersare able to focustheir attentionon one particularauditory stream The purposeof this study is to determinehow well normal-hearing within multi-streamsequences. Such sequences were composedof two to humanscan localizesound sources while wearingprotective headgear with fourisochronous pulses each with a differenttempo (IS[=300, 400, 500 or and without hearingprotection. Six subjectswill participatein a source 700 ms) and frequency(from 234 Hz). The effectivefocusing of attention identification task to be conducted in an anechoic chamber. On each trial on one streamwas obtainedby askingsubjects to detecta local temporal the stimulus(a 100-msbroadband source) will be presentedfrom one of 20 irregularityin a targetstream in the presenceof one, two, or threeother loudspeakersarrayed in a semicirculararc, and the subjectmust state streams.To help subjectsfocus their attention,the multi-streamssequences whichloudspeaker emitted the sound.The arcspans 160 ø in thehorizontal werepreceded by a cuecomposed of the regulartarget sequence. Temporal planeat ear leveland is about1.8 m distantfrom the subject.Each subject irregularitydetection thresholds in the targetstream were measuredusing will be testedin eightconditions, involving various combinations of wear- a 2AFC paradigm(4 up/l down).The resultsshowed, contrary to expec- ing protectiveheadgear and three types of earplugs:the EAR plugand the tations,that the ability to focuson one streamwas independentof the EtymoticERI5 andER25 "musician's"earplugs. In addition,testing will number of streams (no difference in thresholds when more than two be conductedat eachof two orientations:frontal (center of the arrayat streamswere added). So, listenersseem to createtwo perceptualspaces: subject'smidline) and lateral (center of thearray at 90ø azimuth).Results onecomposed of the focusedstream, and one composed of the nonfocused areexpected (a) to revealwhether the Etymoticearplugs (which are de- streams,irrespective of their physicalcharacteristics. It is also easierto signedto attenuateequally across a broadfrequency range) preserve lo- focuson outerstreams (the highest or the lowestfrequency) than on inner calizationaccuracy, and (b) to quantifythe interactiveeffects on localiza- streams. tionperk)rmance of protectiveheadgear and earplugs. [Work supported by NIDCD and NOHR.] 5pPPI0. The influence of grouping and dimensional similarity on interference effects in auditory short-term memory. Gary E. Starr 5pPPI3. Lateralization of nonspeech audio-visual stimulus andMark A. Pitt (Dept.of Psych.,Ohio State Univ., 142Townshenri Hall, combinations. N.J. Holt (Dept. of Psych.,Univ. of York, Heslington, 1885 Nell Ave., Columbus,OH 43210-1222) York YOI 5DD, England) Previousresearch investigating auditory short-term memory using a Ability to lateralizestimuli was measuredin eightnormally heating tone discriminationparadigm found same-dimensionsimilarity to be the subjects.In experimentI auditoryor visualstimuli were presented. Sub- primarysource of memorydisruption [e.g., C. Semaland L. Demany,J. jects respondedwith an auditoryor visual pointerin conditionswhere Acoust.Soc. Am. 89, 2404-2410 (1991)]. However,grouping principles stimulusand response modalities were the same(uni-modal) or different (e.g., Gestaltprinciples) also provide a possibleexplanation for the ob- (cross-modal).A linearrelationship was found between the positionof the servedeffects, because increases in same dimensionsimilarity may also targetstimuli and the perceived lateral position, establishing the correspon- increasethe likelihoodof the standardtone grouping with additionaltones. dencebetween auditorily and visuallypresented positions, consistent with This projectinvestigated the contributionof groupingto interferenceef- Yost[J. Acoust. Soc. Am. 70, 397-409(1981)]. Mean judgments of linear fects in short term memoryfor the dimensionsof pitch and timbre. A positionwere independent of stimulusor responsemodality. In experiment modified"captor effect" taskwas used,with participantsdiscriminating 2 subjectswere presented with bi-modat audio-visual stimuli with spaticily eitherthe pitch or timbreof a standardtone (the sixth tone in an 1l-tone andtemporally correspondent modal components and subjects responded sequence)from a comparisontone presented 5 s afterthe standard.Two withan auditorypointer. Mean judgments of positionwere similar to those variableswere orthogonally varied, the same-dimensiondistance between in experimentI but standarddeviations were significantly smaller for the the standardtone and the captor tones (either close or far), andthe group- hi-modalstimuli relative to uni-modalstimuli. Experiments 3 and 4 in- ing structureof the sequence,with structuresthat eitherpromoted or pro- volved manipulationsof the spatial or temporalrelationship between ventedgrouping of the standardtone with the captortones. Results suggest modalcomponents of bi-modalstimuli. Whereas the relative importance of that groupingcontributes to the amountof interferencebecause increases thevisual modality was confirmed [Colavita, Percept. Psychophys. 15(2), in groupingled to increasesin interference. 409-412 (1974)] the resultsof bothexperiments indicated that perception of the location of an audio-visual stimulus is influencedby information conveyedin bothmodalities. [Work supported by UKBBSRC.] 5pPPII. The effectof a free-fieldauditory target's horizontal motion on itsdetectability. Xin Xiaoand D. WesleyGrantham (Div. of Hearing and SpeechSciences, Vanderbilt Univ. Schoolof Medicine,and Bill 5pPP14.Anticipatory perception of object pass-byusing changing WilkersonCtr., I114 19thAve. S., Nashville,TN 37212) intensity alone: A psychophysiologicalstudy. Terri A. Erwin and Louis G. Tassinary (Environ.Psychophysiology Lab., College of Previouswork hasshown that the motionof an auditorysignal, when Architecture,Texas A&M Univ.,College Station, TX 77845) simulatedover earphones by presentinga binauralstimulus with a chang- ing interauraltemporal difference, does not enhanceits detectabilityrela- Prospectiveinformation, that is, presentconditions of stimulationthat tive to thatof a stationarysignal [Grantham and Luethke, J. Acoust.Soc. are infomrativeabout a futurestate, e.g., the timingand/or location of an Am. 83, I117-1123 (1988)]. The presentstudy will comparethe detect- impendingcontact, is requiredfor coordinatingacts of interceptionand abilityof stationaryand moving auditory targets presented in free-field, avoidance.In thepresent study, acoustic simulations of passingobjects (at whereall cuesfor location,including interaural level differences and spec- differentspeeds and distances) were produced by modulatingthe ampli- tral information,will be available.Six normal-hearingsubjects will be tudeof a l-kHz tonein accordancewith the inversesquare law of acoustic testedindividually in a darkenedartechole chamber. Ma•ked thresholdwill intensity.The simulation•were u•ed to explorelisteners' capacity for au- be determinedin an adaptive,single-interval 2AFC procedurefor targets ditorallyanticipating arrival time simply on the basis of intensitychange-- thatare eitherstationary or movingat variousvelocities. Three different formulatedas a tau variable [see Shaw, McGowan, and Turvey, Ecol. signalswill be employed:a 500-Hztone, an 8000-Hztone, and a broad- Psychol.3, 253-261 (1991)].Subjects indicated either the arrivaltime of bandnoise. Preliminary results from one subjectindicate that motionmay a singlepassing object or the firstarrival within a pair by squeezinga enhancethe detectabilityof broadbandnoise targets, but not of the pure- dynamometer.Response accuracy/variability and anticipatory EMG, SCR, tonetargets. [Work supported by NIDCD.] andEEG activitywere used as indexesto listeners'ongoing awareness of 2597 J. Acoust. Soc. Am., Vol. 99, No. 4, Pt. 2, April 1996 131st Meeting:Acoustical Society of America 2597 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 objectposition during the simulated approach. Preliminary results indicate environment.To investigatethis ability, it is importantto determinethe highlysystematic accuracy and variability,along with the inadequacyof extentof subjects'ability to map soundsonto certainevent characteristics tau as a meansof formalizingthe relevantprospective information sup- and then to determinethe specificacoustic properties which tend to be porting anticipation. used in this mappingprocess. Once this processhas been determined, techniquescan be developedto improvethis ability. Previousresearch fromour laboratory IX. Li, R. J. Logan,and R. E. Pastore,J. Acoust.Sec. Am. 90, 3036-3049 (1991)] indicatedthat subjectsare able to identify 5pPPIS. Detection of timing deviations in simple and complex walkergender based upon acoustic properties of fourfootsteps on a single rhythms. RalphBarnes, Mad ReissJones, and James Klein (Dept.of surface.The currentresearch investigated subjects' ability to identify spe- Psych.,Ohio State Univ., 1885 Nell Ave.,Columbus, OH 43210-1222) cific walkersacross different surfaces. Results indicated that, to varying degrees,subjects could reliably identify walkers across different surfaces Thisexperiment was designed to determinewhether or notpolyrhyth- and could generalizethis training to a novel task. Further experiments mic structureand attentionalset influenceauditory stream segregation. In providea moredetailed analysis of the propertiesof the acousticsignal sequenceswhere streaming does not occurlisteners are oftenquite accu- which reliably map on to subjectsability to identifya specificwalker. rate in detectingsmall time changes,but this is not true when sequences stream. Here a two-alternative forced-choice task was used to examine time discriminationwithin polyrhythmicpatterns involving two different tonefrequencies (high. low). Polyrhythmswith narrow.medium, and wide 5pPPI8. Effects of variable pattern context on temporal acuity. frequencyseparations between high and low toneswere presented to each DanaApfelblat and Mari RiessJones (Dept.of Psych.,Ohio StateUniv., subject;single frequency control patterns were alsoused. Listeners deter- 1885 Nell Ave., Columbus, OH 43210-1222) minedwhether a smalltime changein the rhythmoccurred early or late in a recurrentpresentation of eachpattern. In additionto manipulationof This experimentvaried the time patternof 25 tonessequences to de- frequencyseparation, rhythmic structure (simple, complex) and attentional ternfineits effect on subjects'abilities to discriminatesmall time changes set (selective,divided) were vaded.Results indicated that both frequency within one of two isochronoustest regions.A two-alternativeforced- separation(narrow, medium, wide) and rhythm (simple, complex) affected choiceprocedure was used in whicha smalltime change (+At = 21, 39, or time-changedetection. These findings have implicationsfor theoriesof 57 ms)occurred equally often in oneof the two testregions. Test regions attentionand stream segregation. [Work supported by NSF.] were distinguishedfrom surroundingcontext regions, where timing was variable,by higherfrequency tones. Both the absoluteamount of temporal variability(small, large) and the natureof temporalvariability (rote- accelerating,rate-decelerating, and rate-alternating) within context regions 5pPP16. Dichotic temporal order thresholds. RichardE. Pastoreand were varied. Resultsshowed that listeners'ability to detecttime changes EdwardJ. Crawley (Dept.of Psych.,Binghamton Univ., Binghamton, NY withintest regions was poorer with largeamounts of contextualvariability 13905) than with smalleramounts. However, minimal effectsof the paRemingof Temporalorder thresholds (TOT) weremeasured for dichoticallypre- tempo(rate) within context regions were found. sentedstimuli. Earlier research,using dietic or menauralpresentation, requiredsubjects to respondto the perceivedspectral properties of the earlier onsetstimulus. Dichotic presentationprovides an opportunityfor the subjectto respondto ear with earlieronset, pitch with earlieronset, or 5pPP19.Roughness scaling of complextones. B. JohnFeng (Scientific both.These alternatives allowed two issuesto be evaluated:(!) peripheral Res. Lab., Ford Motor Co., 20000 RotundaAve., Dearborn,MI 48121) and (changesin neuralpatterns) versus central coding and (2) therole of pitch GregoryH. Wakefield (Univ. of Michigan,Ann Arbor,MI 48109) processingin responsespecification. Contrary to argumentsthat TOT is the The term roughnesshas been proposedto describea sensationelicited result of low level interactionsor changesin peripheralcoding, all values for respondingbased on pitch or ear were within the rangeof previous by sinusoidalamplitude modulation (SAM) of puretones and modulated widebandnoise [E. Terhardt,Acusfica 30, 201-213 (1974)].Roughness of findings.Thresholds were largestfor respondingbased solely on pitch presumablybecause temporally greater information is requiredto specify SAM tonesis knownto exhibita closerelationship to modulationdepth. It pitch than ear. In addition,thresholds were smallestwhen subjectscould is hypothesizedthat roughnessof complextones, as scaledagainst modu- lationdepth of a SAM tone,can be predictedfrom the magnitudeof the use a combinationof ear and pitch, possiblyreflecting a simpleror less uncertain task. envelopespectrum. Subjects were askedto scalecomplex tones on the dimensionof roughnessby matchinga test stimulusto a referenceSAM tone of subjectivelyequivalent roughness. The test stimuli were drawn from complextones consisting of a variablenumber of equal amplitude, harmonicallyrelated components.The referenceset was 12 SAM tones 5pPPI7. Perceiving source characteristics from complex sounds. with modulationdepths spanning the rangefrom detectionthreshold to 100 Shannon M. Fartington and Richard E. Pastore (Dept. of Psych., [Viemeister,J. AcousCSec. Am. 88. 1367-1373 (1990)]. The modulation BinghamtonUniv., Binghamton,NY 13905) frequencyof the referenceset variedacross tests conditions according to Otherthan in speech,there have been very few studiesinvestigating the minimum componentspacing of the tests stimulus.Results of the the abilityof humansto perceivecharacteristics of eventsbased upon the scalingexperiments suggest roughness can be predictedas a functionof sounds emitted. However, there is considerable anecdotal evidence that the narrow-bandpeaks in the magnitudespectrum of theenvelope. [Work humans often use complex soundsto accurately i•rc½ivc •vents in their supportedby Ford Motor Company.] 2598 J. Acoust.Soc. Am., Vol. 99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2598 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,17 MAY 1996 CELEBRATIONA, 1:00TO 4:50 P.M. Session5pSA StructuralAcoustics and Vibration:Acoustics of CoupledStructures II CourtneyB. Burroughs,Chair AppliedResearch Laboratory, Pennsylvania State Universi.ty, PO. Box30, StateCollege, Pennsylvania 16801 Chair's lntroduction--1:00 Invited Papers 1:05 5pSA1.Thermodynamic energy flow, modal models, and statistical energy analysis. Dennis S. Bernstein(Aerospace Eng. Dept., Univ. of Michigan, 1320 Beal St., Ann Arbor, MI 48109-2118) The acousticsand vibration of coupledstructures can be efficientlymodeled by meansof energyflow theory,usually known as statisticalenergy analysis (SEA). SEA is basedupon relations derived from the interaction of pairsof coupledmodes and is applied empiricallytocoupled structures possessing multiple interacting modes. This talk investigates the accuracy of SEAmodels by deriving exactenergy flow relationsbased upon modal models. Using white noisedisturbances but otherwisedeterministic structural models, we presentenergy flow relations for multiplecoupled structures. These relations are formulated in termsof thermodynamicenergy, whichis a measureof subsystemenergy dissipation relative to subsystemdisturbance intensity. The resulting energy flow models are comparedto SEAmodels based upon coupled, uncoupled, and blocked subsystem energy. The results are applied to systems of coupled oscillatorsas well ascoupled beams to demonstratepredicted energy flow under both strong and weak coupling. 1:35 5pSA2. The designof a satelliteboom with enhancedvibration performanceusing genetic algorithm techniques. A.J. Keane (Dept.of Mech.Eng., Univ. of Southampton,Highfield, Southampton SO17 IBJ, UK) This paperexamines the application of passivevibration control methods to a simplifiedsatellite boom. It is suggestedthat such methodsmay allow an efficienlmeans by whichto controlstructural vibrations. In thisre,arch. an initialslructurc is designedhaving a regular,repeating geometric pattern. This designis thenmodified using a geneticalgorithm (GA), whichis oneof a numberof recentlydeveloped evolutionary computing methods. Here the GA changesthe geometryof the designby alteringthe three- dimensionalcoordinates of itsjoints. The aim is to minimizethe band-averaged noise transmission along the boom. This paper shows thatby alteringtbe geometryin thisway, significantimprovements in the structm'e'snoise performance can be achieved.While this researchis far from complete.the work outlineddemonstrates the potentialusefulness of this approachfor controllingstructural vibrations. 2:05 5pSA3. Active control of sound transmissionthrough a structureinto a coupledenclosure of arbitrary shape. Ben S. Cazzolatoand Colin H. Hansen (Dept.of Mech. Eng..Adelaide Univ.. S.A., 5005, Australia) A numericalprocedure for assessingthe performanceof an activenoise and vibrationcontrol system for a harmonicallyexcited weaklycoupled multimodal vibroacoustic system is presented.The structureand the contiguousacoustic space have been modeled separatelywith a commerciallyavailable finite element analysis package (^•4s¾s) and then combined using a modalcoupling theory for weaklycoupled systems. Numerical results are compared against experimental measurements for a finitelongitudinally stiflened cylinderwith an integralfloor. Experimental based response matrices were measured and used to predictthe systemresponse. Modal analysiswas applied in orderto reducethe requiredeffort in determiningthe response matrix. A designmethodology for optimizing the physicalcontrol system is reviewedand severaltrends presented. 2:35-2:50 Break Contributed Papers 2:50 applicationsare presentedand their efi•:ctivenessis discussed.For some particularcases the exactnessof the resultsobtained can be estimatedas 5pSA4. Methodsof isolationof modal resonances(a review). Naum well. The following methodsare considered:gradient of the phase,utili- •/½ksler (Inst. of Cybernet[½q,Akadeemia 21, I•[i-0026 Tallinn. Egtania). Jean-Mark Conoir, Jean-Louis Izbicki, and Pascal Reinbert (Univ. Havre, zation of impedance type intermediate backgrounds,Argorid diagram 76610 Le Havre, France) method,and pole evaluationon the frequencycomplex plane for a fixed The analyticalmethods of isolationand descriptionof the resonance tions: for very narrow and rather broad resonances.near the point of componentsof partial modesin scatteringproblems of acoustic,elastic, intersectionof the dispersioncurves of phasevelocities, and for very close and electromagneticwaves are set forth. The resultsof thesemethods' situatedresonances. The illustrativeexamples are given for the problems 2599 J. Acoust. Soc. Am., Vol. 99, No. 4, Pt. 2, April 1996 modeorder.131Thest methods Meeting:canAcoustical beevenusedSociety forratherof Americacomplicated 2599situa- 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 scatteringof bodiesof sphericaland cylindrical shape. The resonances energywhich vanishes as •--* 180ø. An incidentlongitudinal wave gen- are isolatedfor wavesof differentphysical nature: diffracted (Franz type), eratesrelatively little acousticsound for all valuesof ß considered,with normal(Lamb type), shear, Rayleigh type, andwhispering gallery. With most of its energyredistributed among structuralmodes. The acoustical the properlycomputed modal resonances one can immediatelyobtain the diffractionis generallygreater for flexuralincidence. [Work supported by dispersioncurves of the phaseand groupvelocities of every wave, and ON•.] constructthe acousticspectrogram of the scatterer.Jointly with the well- 3:50 knownexperimental methods, the described ones form the basisfor ultra- sonicspectroscopy. 5pSA8. Effects of component interfacial boundary conditions on 3:05 componentmode synthesisestimates for natural frequenciesand modes. JerryE. Furstad (Dept. of Mech. Eng., Univ. of Louisville, 5pSA5. Fuzzy structure massper unit frequencyand its asymptotic Louisville,KY 40292)and Rajendra Singh (OhioState Univ., Columbus, tendencies. Allan D. Pierce (Dept. of Aerospaceand Mech. Eng., OH 43210) BostonUniv., 110 CummingtonSt., Boston,MA 02215) Several formulationsfor componentmode synthesishave been pro- The fuzzy structuretheory concept of modal mass per unit natural posedin the literature,with the principaldifferences among them being the frequencyis exploredfor an elasticsubstructure attached to a masterstruc- types of boundaryconditions imposed on individualcomponents at the ture.The passiveinfluence on themaster structure vibration is specifiedby interfaceswhere they laterwill bejoined when component ngtural frequen- the drivingpoint impedance of thesubstructure, which in turnis expressed cies and modesare computed.Formulations based on componentmodes as a sumover terms,each corresponding to a naturalmode. Term param- with fixed interfacial conditions,free interfacial conditions,and mixtures eters are a modal massin the numeratorand the natural frequency.The of fixed and free conditionshave he en proposed.While all formulations fuzzy structureidealization replaces the sum by a derivativeterm (dissi- yield reliableresults when all componentmodes are included,modal trun- patDepart) plus an integral(reactive part), both involving modal mass per cation errorsare introducedif incompletesets of componentmodes are unit frequency.Generic continuum models of the attachmentare inhomo- used.In thiscommunication, a new procedurefor determiningmodal trun- geneousrods, beams, and plates. (In the lattercases, the impedancebe- cationerrors in modal synthesisformulations is presentedand appliedto comesa matrix,with generalizedforces incorporated that correspondto two formulations, one with mixed interface conditions and one with fixed torques,and generalized velocities that are angular velocities.) Asymptotic interfaceconditions. Errors in estimatednatural frequencies and local er- ideasanalogous to thosethat yield modaldensity predictions yield predic- rors in mode shapesare investigatedfor the caseof a two component tionsof themass per unit natural frequency (and its generalizations)in the joined beamsystem. The resultsindicate that formulationsusing compo- limit of highfrequencies. [Work supported by ONR.] nent modes with free interface conditionsare inherently susceptibleto modaltruncation errors because of nonzeroforces and momentsacting at 3:20 the joints after assembly. 5pSA6, Continuous structures as "fuzzy" substructures. M. 4:05 Strasberg (David Taylor Model Basin, NSWC, Bethesda,MD 20084-5000) 5pSA9. Modal impedancesfor nonaxisymmetricvibrations of a thin sphericalshell. RichardB. Evans (ScienceApplications Intl. Corp.,21 It is by now well lmown that the resistivepart of the combineddriving- Montauk Ave,, Ste. 201, New London, CT 06320) point impedanceof a collectionof sprungmasses with closelyspaced frequenciesof antiresonancecan be expressedby the simple relation Modal impedaneesare foundby solvingthe equationsof motionof a R= !12•r2f2mo,where rn 0 is theresonant mass density, defined so that thin sphericalshell in termsof nonaxisynmnetricmodes of vibration.These modf is the combinedmass of the sprungmasses in antiresonancein a mechanicalimpedances relate the modalexpansion coefficients of the ap- differentialfrequency band of width df centeredat the cyclic driving pliedforce per unit areaand the velocityof the shell,The applicationand frequencyf. To applythis relationto a continuousor complicatedstrnc- interpretationof thesemodal impedances require an awarenessof the lack ture, it is necessaryto determinehow the value of m0 varieswith fre- of orthogonalityof certainmodes. In propercombinations, the modalim- quencyfor a setof sprungmasses duplicating the driving-point impedance pedancesin the nonaxisymmetricease are foundto be identicalto known of the structure.The procedureis illustratedby calculatingm 0 for several modalimpedances in the axisymmetriccase. The analysisis restrictedto simplecontinuous structures, including a long uniformrod in axial vibra- extensionaleffects of a thinshell with radialforcing. An applicationof the tion, anda longuniform beam or largethin platein flexuralvibration. The modalimpedances is givenin the predictionof theradiation pattern of a valuesof resistanceobtained by treatingthese systems as fuzzy structures three-dimensionalarray of closelyspaced interacting spherical shells. agree with well-known values. 3:35 5pSAI0. Investigation of the dynamic responseand stability of a 5pSA7, Interaction of structural and acoustical waves at a Stirlingcycle cryocooler. F.W. Hansle,W. G. Gully (CryogenicsDept., wedge-shapedjunction of two fluid-loaded plates. Andrew N. Norris Ball Aerospaceand Technol.Corp., Boulder,CO 80301}, and LeonardJ. (RutgersUniv., Piscataway, NJ 08855-0909) Bond (Univ. Colorado, Boulder, CO 80309 and Denver Res. Inst., Denver, CO 80208) Two semi-infiniteelastic plates are joined along a line forminga wedge structurewith unilateralfluid loadingin the sectorof angle 2•. The Existinganalytical models for acousticcrytattler vibrationanalysis structureis modeledusing thin plate theory.allowino freely propagating assnineI-D axisymmetricbehavior. A multiplescales g•rturbation analysis flexuraland longitudinalwaves. The junction is mechanicallyconnected is usedto describethe lateraldynamic response and stability of an axially with an appliedforce and momentacting there to simulatea possible oscillatingStirling cycle cryocooler core. The modelof theoscillating core internalconnection. The general2-D solutionis describedfor incidenceof massis assumedto possesstwo degreesof lateralmotion freedom and the time harmonicstructural or acousticalwaves. The methodof Osipov is forcingfunction is multipleharmonic axial motion.A pair of mechanical usedto expressthe total pressureas a Sommerfeldintegral, the integrand springs which support the core mass is assumed to have axial- comprisingMalyuzhiuets functions and particular solutions of certaindif- displacement-dependentlateral stiffnesscharacteristics which resultsin ferenceequations. The junctiouconditions reduce to a systemof eight parametricexcitation of thelateral degrees of freedom.The effect of per- linearequations. Numerical examples indicate the couplingbetween the turbinggas-fluid forces acting on the piston,which disturb the otherwise modesfor differentwedge angles,specifically •=112.5 ø, 135ø, and axisymmetricmotion, is investigated.The perturbationanalysis predicts 157.5ø , for steelplates in water.Acoustic plane wave incidenceon the thedynamic response in closedform and identifies regions of operationfor flatterjunction (112.5 ø) is convertedalmost equally, in termsof energy, unstable/chaoticmotion. The results of theclosed-form dynamic response amongdiffracted flexural and longitudinal waves. The couplingto flexural predictionsare compared with a numericaltime-step Rungs-Kurta method energyincreases with the wedgeangle, at the expenseof the longitudinal [F. Hausle,J. Acoust.Soc. Am. 94, 1853(1993)]. Model results are also 2600 J. Acoust.Soc. Am., Vol.99, No. 4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2600 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 comparedwith experimentaldisplacemenHime-frequency data obtained and tangentialcomponents of the particlevelocity over a surfacethat with a new designof crypeppier.The insightgiven by thisanalysis is enclosesthe object.If this surfacecoincides with that of the vibrating expectedto lead to improvedcrypeppier design based on betterunder- object,then the normalcomponent of the particlevelocity is equalto that standingof the domainof conligurationaland operational parameters. of thesurface velocity, which is normallyassumed given. The tangential componentof the particlevelocity, however, is differentfrom that of the 4:35 surfacevelocity, but is determinableexperimentally by usingan intensity probe.For a classof specialcases in whichthe object dilates uniformly, the 5pSAll. Explicit solution to the Kirchhoff integral formulation. tangentialcomponent of theparticle velocity is identicallyzero. Under this SennF. Wu and Qiang Hu (Dept. of Mech. Eng., WayneState Univ., condition,the radiatedacoustic pressure can be obtainedby directlyinte- Detroit, MI 48202) grating the normal componentof the surfacevelocity over the vibrating An explicit solutionto the Kirchhoff integralformulation for predicting surface,rather than solving the surfaceacoustic pressure first, and thenthe acousticradiation from a vibratingobject is derived.The radiatedacoustic radiatedacoustic pressure, as it is traditionallydone in the numericalso- pressureis shownto be expressiblein termsof integrationsof the normal lutionsto the Kirchhoffintegral formulation. FRIDAY AFTERNOON, 17 MAY 1996 REGENCY D, 1:00 TO 4:00 P.M. Session5pSC SpeechCommunication: Perception by SpecialPopulations Susan L. Hura, Chair DepartmentAudiology and SpeechSciences, Purdue University, 1353 HeavilonHall, WestLafayette, Indiana 47907-1353 ContributedPapers 1:00 identification.Thus, both phonetically-relevantand irrelevantsources of variabilitywere investigated.Age differences,as indicatedby greateref- 5pSCI. The perception of stop consonantsin silent-centersyllables fects of variability for the NHE comparedwith the NHY listeners,were by listeners with high-frequency hearing loss. Janet W. Stack observed for conditions with trial-to-trial variations in talker characleristics (Commun. Disord. Program, Univ. of Virginia, P.O. Box 9022, and overallamplitude. Effects of hearingimpairment, as indicatedby re- Charlottesville, VA 22906-9022} ducedscores for the HIE comparedwith the NHE group,were observed This studyinvestigated whether stop consonant perception in listeners for conditionswith variationsin eitherspeaking rate or talkercharacteris- with high-frequencyhearing loss could be improvedby eliminatingnon- tics.Considered together, the findingssuggest that age-relatedchanges in simultaneousmasking effects of high-amplitudevowels on consonantsin perceptualnormalization, selective attention, and absolute sensitivity may consonant-vowel-consonant(CVC) syllables.Full syllables(FS) con- all contributeto thereduced speech understanding often reported for older tained the consonants/b,d,g/ in all combinationswith eight vowels adults.Several possible mechanisms for the age-and hearing-related defi- (h,t,•,a•,n,a,ul).Syllables were produced by a malespeaker. Silent-center cits are discussed. (SC) syllableswere created by attenuatingvowel steady-state portions to silence.Stimuli were presented to 12normal-hearing (NH) and36 hearing- impaired(HI) adultsunder the age of 60. HI listenershad steeplysloping high-frequencyhearing losses. FS andSC conditionswere presented at 50 1:30 and 80 dB HL. All subjectsshowed more accuratevowel and consonant identification in the FS vs SC condition and at 50 vs 80 dB. Errors were 5pSC3. F0 discrimination and concurrent vowel identification by significantlyhigher on initial than on final consonants.Acoustic analysis hearing-impairedlisteners. Van Summers and Marjorie R. Leek (Army suggestedthe possibilityof both temporaland spectralexplanations for Audiol. and SpeechCtr., WalterReed Army Med. Ctr., Washington,DC this final consonantadvantage. In spiteof experimentalfailure to improve 20307-5001) consonantperception in the HI listeners,suggestions for future research Labelingof concurrentlypresented vowels generally improves with the emergedwhich might enhancethe effect of the SC conditionand the F0 differencebetween vowels (up to a limit of 2 to 4 semitonesdiffer- decrementof nonsimultaneousmasking effects. [Work supported by Vet- ence). One interpretationof this findingis that the processingof F0 dif- eransAdministration.] ferencesbetween vowels allows listenersto group spectralcomponents accordingto a commonfundamental and therebyimprove identification. 1:15 However, the benefit of F0 differencesmay be reduced for hearing- impairedlisteners to the extentthat accuracyin processingF0 is compro- 5pSC2. Stimulus variability and spoken word recognition: The mised by the sensoryimpairment. In this study, normal-hearingand effectsof age and hearingimpairment. Mitchell S. Sommers (Dept.of hearing-impairedlisteners were tested to determineF0 differencelimens Psych.,Washington Univ.. Campus Box 1125.St. Louis,MO 63130) for synthetictokens of five steady-statevowels. The samestimuli were Threeexperiments were conducted to investigatethe effects of ageand thenused in a concurrent-vowellabeling task. Preliminary results indicate hearingloss on the ability to maintainperceptual constancy in spokenword accurateprocessing of F0 differencesbetween vowels, with thresholds recognition.Specifically. lhe studiesexamined how variationsin talker generallybelow 2.0 I-Iz acrossvowels and listeners.On concurrent-vowel characteristics,speaking tale, and overall amplitudeaffected perceptual data collectedthus far, hearing-impairedlistenera showed an overall re- identificationin normal-hearingyoung (NHYJ, normal-hearingelderly ductionin labelingaccuracy relative to normal-heatinglisteners. However, (NHE), andhearing-impaired elderly (HIE) listeners.The threedimensions were selectedbecause variations in voice characteristicsand speakingrate of similar magnitudeacross groups. Additional subjects are beingtested affect featuresof speechsignals that are importantfor word recognition andanalyses correlating performance on theFO task with FO-benefiton the while overallamplitude changes do not have directeffects on phonetic labelingtask will be reported.[Work supported by NIH.] 2601 J. Acoust. Sec. Am., Vol. 99, No. 4, Pt. 2, April 1996 thebenefitto131stlabeling Meeting:associatedAcoustical withFOSocietydifferences of Americabetweenvowels 2601 was 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 tion indicatedCG assimilation.On Xhosaimplosive/pre-nasalized stops, monolingualsshowed CG assimilationand greatlyoutperformed bilin- 5pSC4. ¾bwel recognitionby cochlearimplant patients using a large guals,who showedan SC pattern.Conversely, on Xhosaimplosive/plosive databaseof speakers. PhiliposC. Loizou,Michael E Dorman (Dept.of stopsmonolinguals showed SC assimilation;bilingual discrimination was Speechand HearingSci., ArizonaState Univ., Tempe,AZ 85287-0102), higher,showing GC assimilation.[Work supportedby NIH.] andAndreas S. Spanias (ArizonaState Univ.. Tempe,AZ 85287-7206) Therehave been many reports on therecognition of vowelsby cochlear 2:30 implant patientsfitted with variousdevices. Most of thesereports, how- ever, used a single male and/or female talker to test vowel recognition. 5pSC7. Assimilation of non-native vowel contrasts to the American This paper presentsresults on the recognitionof vowels producedby a Englishvowel system. CatherineT. Best (Dept. of Psych.,Wesleyan largenumber of men,women, and children [Hillenbrand et al.. J. Acoust. Univ., Middletown, CT 06459 and Haskins Labs., 270 Crown St., New Soc.Am. 97, 3099-3111(1995)]. The aim of thisstudy was to investigate Haven. CT 06511), Alice Faber (Haskins Labs.), and Andrea Levitt why certain groupsof speakers,e.g., children, and certain vowels are (WellesleyCollege, Wellesley, MA andHaskins Labs.) harderfor the cochlearimplant patientsto identify.A total of 5 Incraid patientswho hadbeen fit with continuousinterleaved sampling (CIS) sig- The perceptualassimilation model (PAM) [Best et al., JEP:HPP14, nal processorswere used in this study. Patients' performanceon vowel 345-360 (1988)]predicts that two non-nativesounds that are assimilated recognitionranged from 54% to 84%. The sexand ageof the talker(that to the same naturecategory will be harder for listenersto discriminate is, the talker'svocal tract size) seemedto havea significanteffect on the betweenthan sounds that are assimilatedto two differentnative categories performancefor someof thepatients, and in particularthe "poor"patients. (TC contrasts);how difficult will dependon whetherthey are equally good Individualpatient's results on vowel recognition,and a detailedanalysis of (or bad)exemplars of thesingle native category (SC contrasts) or not(CG the vowel confusionswill be presented. contrasts).PAM was basedon studiesof consonantperception, as were subsequenttests of the model.This studyextends the modelto non-native vowels.American listeners performed keyword identification [W. Strange 2:00 andT. L. Gottfried,J. Acoust.Soc. Am. 68, 1622-1625(1979)] andcat- egorical AXB discriminationtasks using six non-nativevowel contrasts, 5pSC5. Hearing impairment and same-different reaction time. Norwegianli-yl, fi-a/, FrenchIo-•l, Ioz-yl, I(e-al, and Thai Io-tul. Philip F. Seitz (Army Audiol. and SpeechCtr., Walter Reed Army Assimilationpatterns for a particularvowel contrast,inferred from key- MedicalCtr., Washington,DC 20307-5001)and BradRakerd (Michigan word results, were more variable than in consonant studies but nonetheless StateUniv., East Lansing,Ml 48824-1212) stronglyrelated to discriminationperformance: TC contrastswere better Reactiontime (RT) studiesprovide information about perceptual and discriminated than CG contrasts, which in turn were better discriminated post-perceptualinformation processing. A prior investigationfound only thanSC contrasts.Moreover, listeners who assimilateda particularcontrast small differencesbetween the mean RTs of hearing-impaired(HI) and in TC fashion were better able to discriminate it than listeners who assimi- normal-hearing(NH) subjectsperforming a simpleRT taskwith subjec- latedit in CG or SC fashion.[Work supported by NIH.] tively loudand soft tonal stimuli.The presentstudy extended that group comparisonto a choiceRT task. Subjectswith early-onset,moderate-to- 2:45 severesensorineural hearing impairments (N=8) andNH controls(N = 14) madesame-different judgments about digit pairs. In an auditorycondition 5pSC8. Perceptual assimilation of German vowels by American spokendigits were presentedat two levelsof loudness,representing the listeners:Context and speakereffects. Winifred Strange (Dept. of endpointsof a subject'sdynamic range. In a visualcondition digits were Commun. Sci. and Disord., BEH 255, Univ. of S. Florida, 4202 E. Fowler shownat the dimmestand brightestsettings of a computermonitor. All Ave., Tampa,FL 33620-8150),Ocke-Schwen Bohn (Kiel Univ., Kiel, subjectsperformed accurately in bothmodalities (>90% correct).Notable Germany),Sonja A. Trent. MelissaC. MeNair, and KatherineC. Bielec findingsregarding RT wereas follows: (l) The intensityvariations had no (Univ.of S. Florida,Tampa, FL 33620) significanteffect for eithergroup; (2) thetwo groups had comparable RTs inthe visualcondition; (3) the HI groupwas significantly slower in the This studyinvestigated American English (AE) speakers'perceptual auditorycondition; and (4) subjects'auditory and visual performance were assimilationof North German(NG) vowelsspoken in 5 CVC contextsby stronglycorrelated for the NH group but not for the HI group. Factors four adultmale speakers.Fourteen NG vowelswere produced in/bVp, affectinggroup and individual differences will be discussed.[Work sup- bVt, dVt, gVt, gVk/syllablesin the sentence"Ich habeCVC gesacht." portedby NIH-NIDCD.] Twelve monolingualAE listenerswere testedon eachspeaker's corpus; consonantalcontext was a within-subjectsvariable. Response categories were indicatedby/hVd/key wordsand IPA symbols.Listeners responded 2:15 by selectingthe AE categorycontaining the vowel mostsimilar to the one 5pSC6. Effects of bilingualism on non-native phonetic contrasts. in the utteranceand ratingits "goodnessof fit." The percentagesof selec- JanetCalderrn and Catherine T. Best (Dept.of Psych.,Wesleyan Univ., tion of the modalAE responsecategory for eachNG vowelranged from Middletown, CT 06459 and Haskins Labs., 270 Crown St., New Haven, 99% for li/-,/il {bestfit) to 41% for IOl•lu/(worst fit). NG front andback CT 0651l) roundedvowels were assimilatedto AE back roundedvowels. However, for sevenvowels, modal category percentages differed by greaterthan 15% Monolinguallisteners often have difficulties discriminating non-native acrossthe five consonantal contexts. There was also significant variation in contrasts.The PerceptualAssimilation Model (PAM) [C. T. Best,G. W. assimilationpatterns across the four speakergroups for ! ! of the NG McRoberts,and N.M. Sithole,JEP:HPP 14. 345-360 (1988)] predicts vowels.Thcac results have implications for theoriesof L2 speechlearning. poordiscrimination if two non-nativesounds assimilated equally well to a [Wbrksupported by NIDCD.] singlenative category (SC), gooddiscrimination if a categorygoodness (CG) differenceis perceived,and excellent discrimination if soundsare assimilatedto two differentcategories (TC). However,implications for 3:00 bilinguallisteners are uncertain.Do bilingualsmaintain two separatepho- 5pSC9. Acquisitionof non-nativevowel categories. JohnKingston, noiogicalsystems, or do the systemsinteract to enhanceor inhibit non- Christine Bartels, Jose Benki, Deanna Moore, Jeremy Rice, Rachel native discrimination?In this study,monolingual English and bilingual Thorburn,and Nell Macmillan (Linguist.Dept., South College, Univ. of Spanish/Englishlisteners discriminated and categorizedSpanish lb-p], Massachusetts,Amherst, MA 01003) Englishlb-phi, and three Xhosa bilabial stop contrasts. Both groups dis- criminatedEnglish [b-p h] excellently, asdid bilinguals for Spanish lb-p], Is the acquisitionof foreignphoneme identification determined by na- which monolingualsdiscriminated less well, consistentwith CG assimila- tiveabstract categories ]Best, Development ofSpeech Perception, pp. 167- tion. Compatiblewith PAM, monolingualsshowed excellent TC perfor- 224 (1994)]or byparticular tokens [Pisoni et el., Developmentof Speech manceon Xhosaunaspirated/aspirated stops; bilinguals' lower discrimina- Perception,pp. 121-166 (1994)]? If Best is correct,members of all in- 2602 d. Acoust.Soc. Am., VoL 99, No.4, Pt. 2, April1996 131stMeeting: Acoustical Society of America 2602 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 stancesof the samephonological contrast should be equallyeasy to iden- 3:30 tify. If Pisoniet el. arecorrect, then listeners should not generalize to new 5pSCll. Modelingthe categorizationof a large F1-F2-F3 speakersor contexts.The acquisition by American English listeners of the continuumby Finnishlisteners. TerrenceM. Neareyand Michael potentiallyfour front rounded German vowels/y:,y,oe:,oe/was examined. Kiefte (Dept.of Linguist.,Univ. of Alberta,Edmonton, AB T6G 0•2, Speakerand consonantal context were manipulated. Listeners improved Canada) withtraining. Our listeners, in contrastto thoseof Pisoniet el. (1994), generalizedto new speakers and contexts. Contrary to Best's1994 predic- A continuumof 972 vowelswas synthesized, each of whichwas 115 tion that identificationof the samecontrast would be equallyeasy, it was msin durationwith a fallingF0 contour(125-100 Hz). FI ranged(in 0.5- foundin thisstudy that listeners who heard one set of speakersidentified Barksteps) from 250 to 760 Hz, F2 from750 to 2260Hz andF3 from themid tense:lax/oe:,oe/pair more accurately than the high/y:,y/pair, and 1360 to 3080 Hz. F4 and F5 were fixed at 3500 and4500 Hz, respectively. identifiedthe lax high:mid/y,oe/ pair more accuratelythan the tense (Constraintswere placed on formantseparations to ensurerelatively natu- /y:,oe:/pair.Listeners who heard a secondset of speakersreversed these ral stimuli.)This continuumwas previouslycategorized by a groupof inequalities.Thus assimilation makes generalization to novel stimuli pos- Englishspeakers IT M. Neareyand M. Kiefte,J. Acoust.Soc. Am. 96, siblebut does not preclude sensitivity tophonetic differences. [Work sup- 3284(A)(1994)]. The same stimuli were presented to 14speakers of Finn- portedby NIH GrantNo. 5-R29-DC01708and NSF Grant No. DBD92- ishat the Universityof Turku.Subjects categorized these stimuli with 12043.] labelsfor thenine Finnish vowels, / i, e, y,/5, a:, u, o/. Resultsof logistic regressionanalysis will be presented and compared with previous findings 3:15 forEnglish. [Work supported bySSHRC. The assistance of Ulla Fisher and Dr. Olli Aaltonenof theUniversity of Turkuin collectingthe Finnish data 5pSC10.Preferred onsets. lan Maddieson (Dept. of Linguist.,UCLA, is gratefullyacknowledged.] 405 HilgardAve., Los Angeles, CA 90096-1543) Previousanalysis of segmentinventories (e.g., by Maddieson,1984 3:45 andLindblom and Maddieson, 1988) has shown that, across a largesample of languages,the segmentsthat more commonly occur contrastively are 5pSC12,Arabs' stressplacement in English:Inteiligibility test. thosethat are less complex on an intuitivescale of simplicity.But a seg- FaresMitleb (EnglishDept., Yarrnouk Univ., Irbid, Jordan) menttype within any given language may occur in manyor few words: segmentsthat occur in moreitems may also be those that are in somesense Thisstudy was intended to givean impressionisticdescription of moresimple, or those that combine best with other segments in sequences. Arabs'performance in English stress placement. Two native British En- Within-languagefrequency of usagemay therefore serve to showthat glishspeakers were asked to evaluate the productions of English words by segmentsof (near-)equal frequency in termsof meremembership in in- sixArabs. Findings indicated that the Arab subjects' "conscious knowl- ventoriesin fact showdifferent preference patterns. However, because edge"of a stressfulspeaking situation was less than satisfactory. Listeners thereare many idiosyncratic properties of individuallanguages, it is im- reporteda great percentage of confusion in stress placement. A number of portantto lookacross a range of languagesto reach general conclusions. explanationswere attempted for theintelligibility problem which arises Thepresent paper reports on the relative frequency of thedifferent onset fromthe misplacement of stress in thesubjects' productions. It was also consonantsfound in the universallypresent syllable type CV in a global inferredfrom the confusionArabs made that suprasegmentals should be sampleof 31languages ( 10 from Asia, 8 fromthe Americas, 6 from Africa, givenemphasis in the teaching offoreign languages and should be taught 3 fromEurope, and 4 fromthe Pacific area). The counts are based on simultaneouslywith segmental structure of thetarget tongue. [Research lexicalfrequency. [Work supported in part by NIH.] supportedby YarmoukUniv.] 2603 J. Acoust.Soc. Am., Vol, 99, No. 4, Pt. 2, April 1996 131stMeeting: Acoustical Society of America 2603 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