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Influence of statistical surface models on dynamic scattering of high-frequency signals from the ocean surface (A)
Bjerrum-Niese, Christian; Jensen, Leif Bjørnø
Published in: Acoustical Society of America. Journal
Link to article, DOI: 10.1121/1.411137
Publication date: 1994
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Citation (APA): Bjerrum-Niese, C., & Jensen, L. B. (1994). Influence of statistical surface models on dynamic scattering of high- frequency signals from the ocean surface (A). Acoustical Society of America. Journal, 96(5), 3232-3232. DOI: 10.1121/1.411137
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PROGRAM OF
The 128th Meeting of the AcousticalSociety of America
Stouffer Austin Hotel ß Austin, Texas ß 28 November-2 December 1994
NOTE: All Journalarticles and Lettersto the Editor are peer reviewedbefore publication. Program abstracts,however, are not reviewedbefore publication, since we areprohibited by time andschedule.
MONDAY MORNING, 28 NOVEMBER 1994 SABINE ROOM, 8:00 A.M. TO 12:15 P.M.
Session laAO
AcousticalOceanography: Acoustic Inversions for Propertiesof GaseousSediments
Michael D. Richardson,Chair Naval ResearchLaboratory, Stennis Space Center, Mississippi 39529-5004
Chair's Introduction---8:00
Invited Papers
8:05
laAO1. Biogeochemicalprocesses controlling gas bubble production and distribution in organic-rich sediments. ChristopherS. Martens(Marine Sci., CB-3300, Univ. of NorthCarolina, Chapel Hill, NC 27599-3300),Daniel B. Albert (Univ. of NorthCarolina, Chapel Hill, NC), HanneloreFiedler (ForschungsanstaltderBundeswehr fur Wasserschallund Geophysik, 2300 Kiel, Germany),and FriedrichAbegg (Geologisch-PalaontologischesInstitut und Museumder UniversitatKiel, 2300 Kiel, Germany) Biogeochemicalprocesses in organic-rich, muddy sediments often result in thenet production of biogenicgases including methane. In coastalsediments, methane production ultimately leads to nearsaturation gas concentrations and bubble formation. Rates of production,oxidation, and transport processes, together with in situ temperature and pressure (depth), combine todetermine the actual sedimentcolumn depth of methanebubble occurrence. Recent studies along North Carolina's Outer Banks and Eckemfoerde Bay in theBaltic Sea reveal how these processes combine to controlsaturation gas concentrations and bubble distributions in the upper few metersof coastalsediments. At the NorthCarolina site, gas production depths vary seasonally, resulting in a bubblelayer whose shallowestdepth oscillates between 10- and30-cm depth from summer to winter,respectively. Large quantities of gasescape the sedimentsvia diffusionand bubble ebullition during the warm months. Similar oscillations in thedepth of thebubble (acoustic absorption)layer appear to occurin thesediments of EckernfoerdeBay; however, competing microbial processes prevent saturation methaneconcentrations at depths above approximately 50 cm.Stable isotope measurements reveal that microbial methane oxidation consumesmethane transported above the bubble layer, resulting in littlerelease of gasinto the water column.
8:25
laAO2. Predictionsof the acousticresponse of free-methanebubbles in muddysediments. Anthony P. Lyons,Michael E. Duncan(Dept. of Oceanogr.,Texas A&M Univ.,College Station, TX 77843-3146),James A. Hawkins,Jr. (NavalRes. Lab., StennisSpace Center, MS 39529-5004), and AubreyL. Anderson(Texas A&M Univ.,College Station, TX 77843-3146) Theresponse of the sediments of Eckemfoerde Bay, Germany toacoustic remote sensing has been attributed togas features found withinthe sediment.The existenceof featuresas smallas 0.5 mm equivalentspherical radius has been confirmed by x-ray computed tomographyof cores taken and scanned under in situpressures. The interaction of an acoustic pulse from the Acoustic Sediment ClassificationSystem (ASCS) with this type of gassysediment was modeled. The bubble scattering response included the effects of shearmodulus and nonspherical bubbles. Model predictions made using the observed gas feature distribution and normal incidence ASCSdata agree and show extended returns (greater than a pulselength) from the seafloor bubble layers as well as high attenuation
3217 J. Acoust.Soc. Am., Vol. 96, No.5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3217
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp withinthe bubble layers. These results show that the acoustic rentms from the gas bubble layers are probably due to scatteringand that differences in level of return can be attributed to random variations in the distributions of scatterers.
8:4•
laAO3. The effectsof free-methanebubbles on the propagationand scatteringof compressionaland shear wave energyin muddy sediments. MichaelD. Richardson,Scan R. Griffin, Kevin B. Briggs (Naval Res. Lab., $tcnnisSpace Center, MS 39529-5004), AubreyL. Anderson,and Anthony P. Lyons (TexasA&M Univ.,College Station, TX 77843-3146)
Free-methanebubbles cause significant scattering of acousticenergy in thesoft sediments of EckernfoerdcBay, Baltic Sea. In situ and laboratorymeasurement of sedimentgeoacoustic and physicalproperties were made in an attemptto understandthe physical mechanismsresponsible for thisscattering. In situshear wave velocities (at 100-500 Hz) increasedfrom 5-7 nearthe surface to 15-20 m s-• at2 m intothe seafloor, whereas in situcompressional wave velocities (at 38 and58 kHz) varied litfie (•1425 ra s- •) withdepth. Methane bubblesapparently caused significant attenuation of compressionalwaves at depthsbelow 1 m, whereasshear wave attenuationwas unaffected by gasand decreased with depth.Compressional waves (at 400 kHz) in cores(1%-5% freegas} maintained at in situpressures were highly attenuated but showlittle evidenceof velocitydispersion. Comparison of gcoacousticdata with theory suggestthat primarycontrol of the interactionof acousticprofilers with thisgassy seafloor is by bubbleslarger than about 1 mm diameterand that the observedhigh-frequency scattering can be describedby modelsof the seafloorbubbles as individualscarers of acousticenergy. Response of theseafloor as a mediumwith modifiedbulk propagation properties would occur at lowerfrequencies thanthose used in the Eckemfoerdeexperiments.
9:05
1aAO4.Modeling of high-frequencyacoustic wave scattering by sedimentgas voids. DajunTang (Dept.of Appl.Ocean Phys. andEng., Woods Hole Oceanographic Inst., Woods Hole, MA 02543) Scatteringby volumetricinhomogeneities of marinesediments comes in manyforms. It is foundin a 1993CBBL-SRP experiment conductedin EckernfocrdeBay, Germany,that high-frequency backscattering is causedby gasvoids buried, at abouta meterbeneath theseafloor [Tang et el., I. Acoust.Soc. Am. {to be publishcd)].The backscatteringstrength at 40 kHz is estimatedto be -10 dB. Assumingthe gas voids do notresonate, a simplescattering model is developedbased on theKirchhoff approximation to calmlatethe backscatteringand bistatic scattering strength. Acoustic ray bendingdue to thesound-speed discontinuity at thewater-bottom interface as well as sedimentattenuation are takeninto account.We find that at 40 kHz, only thosegas voids whose exposed cross section is largerthan the acoustic wavelength contribute to backscatteringsignificantly. The gasvoid distributionis estimatedbased on datafrom the few coresobtained in situ. The modelresults are comparedwith backscatteringdata, and it is intendedthat this modelbe usedto comparewith bistatic scattering data in thefuture. [Work supported by ONR throughNRL.]
9:25-9:40 Break
ContributedPapers
attenuation,sediment density values from diver-collected cores, and values for interfaceroughness parameters from underwater photogrammetry were laAO5. Geophysicalground-truthing experiments in Eckernfoerde usedto calculatethe parametersfor the compositeroughness model. The Bay. AngelaDavis, DCI Huws, and Run Haynes (Schoolof OceanSci., modelprediction for scatteringstrength from the sedhncnt-water interface Univ.College of NorthWales, Manai Bridge, Gwynedd LL59 5EY, U.K.) fell well belowthe measuredvalue, indicating that volume scattering from During the 1994 CoastalBenthie BoundaryLayer SpecialResearch within the sedimentwas the dominantprocess. Data obtainedby other Program's(CBBLSRP) experiment in EckemfoerdeBay, multichannel investigatorsreveal a layer of free methanelocated approximately 1 m digitalseismic and electricalresistivity data were collectedusing surface below the sediment-waterinterface. These gas bubbleswere evidently and bottomtowed arrays. Profiling with a bottomtowed sledge yielded responsiblefor the high level of backscatteringobserved. A fit of the shearwave velocity and electricalresistivity data indicativeof the struc- volumescattering component of the composite-roughnessmodel to the turalstrength of the sedimentand of the propertiesof the sediment'spore data providesa measureof the contributionof thesebubbles to acoustic space.Shear wave velocitiesfor the gassymud were, as expected,ex- backscatter. tremelylow, rangingfrom <10 at the surfaceto around16 m/s at 2 m. Variationsin electricalproperties were currelatablewith lithological 10:10 change.It is anticipatedthat analysisof reflectionresponses will provide significantadditional geotechnical ground-truthing. laAO7. Double monopole resonanceof a gas-filled cavity in a sediment. StevenG. Kargl,Kevin L. Williams (Appl.Phys. Lab., Univ. of Washington,1013 N.E. 40th St., Seattle,WA 98105), and Raymond 9:55 Lira (CoastalSystems Station, Panama City, FL 32407-7001) laAO6. High-frequencybottom backscattering:Volume scattering from gassymud. Kevin B. Briggs,Michael D. Richardson(Seafloor The monopoleresponse of a gas-filled,spherical cavity in a sediment SCI. Branch,Naval Res. Lab., SteunisSpace Center, MS 39529), and is investigated.The sedimentis a saturated,poroelastic medium and we Darrell R. Jackson (Appl. Phys.Lab., Seattle,WA 98195) assumethat its dynamicalbehavior satisfies a homogeneousBlot theory. Our methodentails the scatteringof an incident,(fast) longitudinal field Bottombackscattering data at 40 kHz werecollected from a stationary that preferentiallyexcites a monopoleresponse of the cavity.Our main tripoddeployed in a muddyembayment characterized by subsurfacemeth- resultdemonstrates that a gas-filled,spherical cavity in a saturated,po- anegas. Near-surface sediment geoacoustic, physical, and roughness prop- roelasficmedium exhibits two distinctmonopolc resonances. These reso- ertieswere measured concurrently with the acousticdata in orderto com- nancesarise from the two distinctlongitudinal modes of propagationin paremodel predictions with measuredbackscatter strength as a functionof saturated,poroclastic medium as describedby Biot'stheory. The sensitiv- grazingangle. In situvalues for sedimentcompressional wave velocity and ity of theseresonances to various environmental parameters (such as per-
3218 J. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3218
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp roeabilityand porosity) will be presented and discussed. [Work supported assessmentof sub-bottom variations on theacoustic propagation. Prelimi- by ONR.] naryresults are presented and interpreted in lightof normal-modetheory.
11:10 10:25 laAOll. A dynamicpenetrometer for rapid assessmentof seafloor laAO8. Acoustic backscatter from bubbles confined in sediment parameters. T. Akal (SACLANT UnderseaRes. Ctr., 19138 San pores. FrankA.Boyle and Nicholas P. Chofiros (Appl. Res. Labs., Univ. Bartolomeo,La Spezia,Italy) and R.D. Stoll (Lamont-DohenyEarth of Texasat Austin,P.O. Box 8029, Austin,TX 78713-8029) Observatoryof ColumbiaUniv., Palisades, NY 10964) A modelfor acousticbackscatter from trapped gas bubbles in sandy Informationon geoacoustic and geotechnical parameters of theseafloor sedimentswas recentlypresented IF. A. Boyleand N. P. Chotiros,J. is importantin sonarperformance evaluation as well as in engineering Acoust.Soc. Am. 93, 2397(A)(1993)]. One of theassumptions was that applications.Since measurement of theseparameters using traditional trappedbubbles respond to an ambientacoustic field as if theywere free methodsusually involves some rather elaborate experimental procedures, bubblessurrounded by an infinitevolume of water.A refinementto this thereis theneed for a simplesystem that can remotely measure some of modelincludes the effects of solidparticles surrounding and constraining theseparameters from a movingship or aircraft.To accomplishthis a new thefluid around the bubbles. A newexpression for thesediment backacat- techniqueusing a probesimilar to the expendablebathythermograph totingstrength accounts for fluidconfinement in pores.This confinement (XBT) hasbeen developed wherein the thermistor used to measurewater affectssediment acoustic impedances, bubble resonances, and scattering temperatureis replaced by anacceleromcter. When the probe first impacts crosssections. Blot fast and slow compressional waves are treated sepa- thebottom there is rapiddeceleration controlled by theshear strength of rately.[Work supported by NavalRes. Lab., Stennis Space Center.] thesediment, followed by a periodof dampedoscillation with frequency dependenton thegeoacoustic properties of thesediment. Thus when the 10:40 impactsignature is fully analyzedit is possibleto obtaininformation on boththe shearingstrength of the bottomas well as the geoacousticprop- laAO9. Bistaticacoustic scattering from trapped gas bubblesin erties.At presenta seriesof laboratoryand field tests are being carried out sandysediments. Frank A. Boyleand Nicholas P. Chotiros (Appl. Res. in a cooperativeprogram at Lamont-DohertyEarth Observatoryand Labs.,Univ. of Texasat Austin,P.O. Box 8029,Austin, TX 78713-8029) SACLANT Centre.Preliminary results of this work are presentedin this paper.[Work supported by ONR.] A techniquebased on acousticreciprocity has recently been used to calculatebackscattering strengths of marinesediments IF. A. Boyleand N. 11:25 P.Chotiros, J. Acoust.Soc. Am. 93, 2397(A)(1993)]. The method begins withcomputation of the pressure induced at anelement of scatteringvol- laAO12. Shear wave attenuation estimates from inversion of Scholte umein thesediment. The pressure returned to a projectoris thenobtained wave data. HassanB. Ali and Michael K. Broadhead (Code 7173, via a reciprocalrelationship between source and scatterer. A similartech- Naval Res.Lab., Stennis Space Center, MS 39529-5004) niqueis developed topermit the calculation of bistatic scattering strengths. Thistechnique is combinedwith a Blotmodel for acousticpenetration and On the basisof the correlationbetween sediment stratigraphy and a scatteringmodel involving trapped bubble resonance scattering, to arrive modaldispersion, inversion of Scholtewave data allowsone to estimate ata bistaticsandy sediment acoustic scattering model. [Work supported by theshear wave velocities within the sediments. In somecases, this may be NavalRes. Lab. StennisSpace Center under the MCM TacticalEnviron- a sufficientcharacterization of the sediments.However, shearvelocities mentalData System(MTEDS) project.] containonly part of the wave information,and this will not generally sufficefor recoveryof the full measuredtime series.In realisticsediments, a propagatingpulse will alsobe affectedby the attenuationprofile of the 10:55 medium.Moreover, the amplitudes of theconstituent frequencies will gen- erallybe attenuateddifferently, resulting in distortionof the pulse.Using laAO10. Experimental determination of broadband propagation theresults of recentdeep-water measurements, examples are presented of underknown geophysical conditions. Mohsen Badiey (Officeof Naval the relationshipbetween sediment stratigraphy and Scholtewave modal Res.,800 N. QuincySt., Arlington, VA 22217-5666), Mike Steele (Bolt dispersion.The modelingis thenextended to examinationof seismogram Beranek and Newman Syst. and Technol., Arlington, VA 22209), parameters,using iterative analysis of the shearattenuation profiles and WilliamCarey (Adv.Res. Project Agency, Arlington, VA 22203-1714), exploitationof thespectral properties of thetime series. It is shownthat the and PejhanPeymani (Bolt Beranekand NewmanSyst. Technol., shearQ profileis crucialin achievingan adequatematch to the measured Arlington, VA 22209) data,but some degree of nonuniquenessis possible. [Work supported by Acousticpropagation experiments were conducted with explosives,an Officeof Naval Res.,Prog. Element No. 0601153N,with technicalman- air gun,and a continuoussource on the New JerseyContinental shelf near agementprovided by the Naval Res.Lab.] theAMCOR borehole6010. This particular area was extensively surveyed by Davieset al. [Marne Geol. 108, 323-343 (1992)] and is the siteof 11:40-11:45 Break previousacoustic experiments by Careyet al. [Saclantcen,CP 42, al-a27 (1993)].Environmental measurements of temperature, conductivity, salin- 11:45-12:15 ity,sound speed, and bathymetry were made and the signals were received ona verticalarray at a sufficientdistance from the known source positions. PANEL DISCUSSION: Frequency-timeanalysis allows for the determinationof the dispersive Panel Moderator: Michael D. Richardson groupvelocities. The relativeposition of the sourcesprovides for the PanelMembers: Anthony P. Lyons,Christopher S. Martens,Dajun Tang
3219 d. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128th Meeting:Acoustical Society of America 3219
Downloaded 27 Jun 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, 28 NOVEMBER 1994 SAN ANTONIO ROOM, 9:00 A.M. TO 12:00 NOON
Session laPA
PhysicalAcoustics: Thermoacoustics
Robert M. Keolian, Chair PhysicsDepartment, Naval PostgraduateSchool, Monterey, California 93943
ContributedPapers
9:00 AnthonyA. Atchley (Phys.Dept., Naval Postgraduate School, Monterey, CA 93943) IaPAI. Numerical study of various thermoacoustic refrigerator configurations. ThomasJ. Hofler (Phys. Dept., Naval Postgraduate Recentdevelopments in thermoacousticdevices have generateda re- School,Monterey, CA 93943) newedinterest in finite amplitudestanding waves and the nonlineareffects associatedwith them.In a typicalthermoacoustic device, a stackand two The resultsof numericalmodels and optimizationsfor variousconfigu- heatexchangers are placedinside a resonatorapproximately midway be- rationsof thermoacousticrefrigerators will be presented.The refrigeration tweenthe velocityand pressure antinodes. These elements, consisting of goalsare large-scalerefrigeration with low temperaturespan, high effi- closelyspaced rigid plates,present both a discontinuityin the fluid flow ciency,and reasonablyhigh powerdensity. The physicalequations used and a rigid boundarywith which the fluid can interact.Under these con- are the usualplane wave Rott formulationwith improvedsolutions for the ditions,at leasttwo well-known effects may occur: acoustic streaming and heatexchangers and shaped resonator ducts. The primary emphasis will be on solutionshaving the highestsystem efficiency, excluding losses asso- turbulence.These effects are of particularinterest since they could signifi- cantlyaffect the thermoacousticheat transportinside the stack.In this ciatedwith electricaldrivers and secondary heat exchange. study,the fluid velocity inside and near a stackwas measured qualitatively andquantitatively using a stroboscopiclamp and a laserDoppler veloci- 9:15 meter,respectively. Measurements under different conditions will be pre- sentedand discussed. [Work supported by ONR.] laPA2. Simplified model for the study of nonlinear processesin thermoacousticengines. A. Prosperettiand M. Watanabe (Dept. of Mech. Eng., JohnsHopkins Univ., Baltimore,MD 21218) 10:00
Upon integratingthe governingequations over the crosssection of a laPAS. Numericalmodeling of unsteadyflow in the neighborhoodof thermoacousticdevice, a simplifiedone-dimensional model is obtained. a thermoacousticstack. A. S. Worlikarand O. M. Knio (Dept.of While only approximate,this model renders the studyof nonlineareffects Mech. Eng., JohnsHopkins Univ., Baltimore,MD 21218) veryamenable to analysis.In particular,for a thermoacousticprime mover, the stabilitylimits are calculatedand the steady-stateamplitude is esti- A low-Mach-numbercompressible flow modelfor the simulationof matedon the basisof a weaklynonlinear theory. For largeramplitudes, acousticallydriven flow fieldswithin thermoacousticcouples is con- numericalresults are presented.The markedpropensity of the systemto structed.The modelis basedon theassumption that length of thethermoa- developshock waves is foundto be a verystrong factor limiting its effi- cousticstack is muchsmaller than the wavelength of thedriving standing ciency.[Work supported by theOffice of NavalResearch.] wave.The latterassumption is usedto obtaina simplifieddescription of theimpact of acousticwaves while retaining all of theessential features of the unsteadyflow developingin the neighborhoodof solidboundaries. 9:30 Resultsof numericalsimulations are presented which illustrate the nonlin- laPA3. A nonlinearanalysis of a simple thermoacousticsystem. earresponse of theflow to differentdriving amplitudes and frequencies. RonaldE. Kumon (Appl.Res. Labs., Univ. Texas at Austin, 10000 Burnet [Worksupported by theOffice of NavalResearch.] Rd., Austin,TX 78713)
A simplethermoacoustic system was studied to try to betterunderstand 10:15 the interactionbetween the temperature,pressure, and velocity modes of the system.The systemconsidered was a one-dimensional"tube," closed laPA6. Experimental visualization of heat transfer and fluid flow andisothermal at bothends and filled with a heliumgas. Initially, the gas processesin a thermoacousticdevice. C. Herman,C. Bartscher,M. is staticbut with a sinusoidaltemperature distribution. To obtaina simpli- Wetzel,and M. Volejnik (Dept.of Mech.Eng., Johns Hopkins Univ., fiedmodel of thesystem, a Galerkin-typemethod was applied to thefull Baltimore, MD 21218-2686) hydrodynamicequations in onespatial dimension and the ideal gas law Differentvisualization techniques are used to gaininsight into the heat equationof state.By substitutinghighly truncated sine and cosine series in transferand fluid flow processes in a thermoacousticrefrigerator model. the spatialvariable with time-dependent amplitudes into the aforemen- For this pnrpose,an enlargedmodel of a thermoaeougtiedevice, with tionedPDEs, the model was reduced to a setof couplednonlinear ODEs. transparentviewing windows in regionsof interest,was built. The model First,these equations were lineafized and examined for seriesexpansions operateswith air at atmosphericpressure as theworking fluid. The cross with different numberof terms.Next, the nonlinearODEs were studied. sectionof the resonanttube is rectangularto obtainessentially two- Finally,these results were compared with directfinite-difference calcula- dimensionalflow andtemperature fields and to allowtransillumination of tionsusing MacCormack's method to integratethe full hydrodynamic thestack region with parallel laser light. On-line holographic interferom- equations. etrycombined with high-speedcinematography is used to analyzeand measurethe unsteady oscillating temperature fields in thestack region. The 9:45 designalso allows the visualization of the flow fields by smokeinjection andthe visualization of the temperature distribution on thestack plates laPA4.Experimental study of acousticturbulence and streamingin usingthermochromatic liquid crystals. The resultsof the visualizationex- a thermoacousticstack. D. FelipeGaitan, Ashok Gopinath, and perimentsprovide new information on thestability and transition of the
3220 d.Acoust. Soc. Am., Vol. 96, No. 5, Pt.2, November1994 128thMeeting: Acoustical Society ofAmerica 3220
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp flowin thestack region and on theheat transfer processes. [Work sup- acousticsound sources or refrigerators.An immediateadvantage of the portedby the Officeof Naval Research.] radialgeometry is the separationof highermodal frequencies from the higherharmonics of thefundamental when the engine is workingat large 10:30-10:45 Break amplitude.Criteria recently developed for deciding which geometry isbest will be presented.This will be followedby a comparisonof planeand radialwave refrigerators and sound sources. The short stack approximation 10:45 for bothgeometries will be usedin thecomparison. Our derivation of this approximationis not limited by theadditional boundary layer approxima- IaPA7. A thermoacousticpin stack. F. ScottNessler and RobertM. tion.[Work supported by 0NR.] Keolian (Dept. of Phys., Code PH/Kn, Naval PostgraduateSchool, Monterey,CA 93943) 11:30 A comparisonof the pin stack geometrywith a conventionalrolled geometryfor thermoacousticengines is beingmade in a modularprime laPA10. Design of a radial mode thermoacoustic prime mover movertest rig. By decreasingviscous energy losses, it is hopedthat the pin (sound source)and experimentalobservations, Jay A. Lightfoot stackwill improvethe efficienciesof thermoacousticengines. The stack (Dept.of Phys.and Astron., Univ. of Mississippi,University, MS 38677), will consistof overtwo thousand75-/•m wires,separated by 750/tin, in a W. Patrick Arnott (Univ. of Nevada,Reno, NV 89506), Richard hexagonallattice hand sewn between two tinnedcopper heat exchangers. Raspet,James R. Belcher,and Henry E. Bass (Univ. of Mississippi, A temperaturegradient will be appliedto the stackand the neonworking University,MS 38677} fluid by holdingone exchangerat 300 K and the otherat 77 K. A small Experimentalthermoacoustics has been limited in the pastto plane acousticdriver in the rig will allow us to measurethe qualityfactor O wavesystems. Swift brieflydiscussed the radialmode thermoacoustic en- belowonset as a functionof theneon pressure. [Work supported by ONR.] gine,but no working models have been built. Radial modes of a cylindrical resonatorare naturallyartharmonic; thus harmonicgeneration at high 11:00 sound-pressurelevels by nonlinearprocesses tend to be less resonance enhancedin the radialmode, potentially leading to highersound-pressure laPAS. Thermoacoustic sound source in the Helmholtz limit. levelsin the fundamentalradial mode of oscillation.A radialmode prime RichardRaspet, Jay A. Lightfoot,James R. Belcher,and Henry E. Bass moverwhich is theoreticallyoptimized for a 60% helium,40% argongas (Dept.of Phys.and Astron., Univ. of Mississippi,University, MS 38677) mixture(mole fraction) at atmosphericpressure has been constructed. De- Thermoacousticengines are placed in resonantcavities for Q amplifi- tailsof thedesign and construction, measurement of the powerdissipa ed cation. Variations in the cross-sectional area of the resonator serve to re- in the hot heat exchanger(required for onsetof self oscillation)as a ducedevice volume and to minimizenonlinear distortion by aletuning functionof ambientpressure, and harmonicdistortion of the fundamental higher harmonics.In the case of a thermoacousticsound source,these modeof oscillationwill be presented.[Work supported by ONP,.] cross-sectionalvariations in the resonatorarea may be carried to an ex-
tremesuch that the resonatorapproaches the Helmholtzlimit. This limit 11:45 producesa dimensionallycompact, low-frequency thermoacoustic sound source. A thermoacoustic sound source in the Helmholtz limit has been laPAll. Investigationof parametric drive of a longitudinal gas filled constructed.The measuredparticle velocity and acousticpressure in the resonancetube. RichardRaspet, Bruce Denardo,James Brewster, and devicewill be comparedto Helmholtzidealization. [Work supportedby JohnKordomenos (Dept. of Phys.and Astron.,Univ. of Mississippi, ONR.] University,MS 38677}
High-powerdrives for thermoacousticrefrigerators are beinginvesti- 11:15 gatedby severalgroups. Theoretical calculations have been performed of the feasibilityof parametricallydriving a longitudinalresonance tube by IaPA9. Radial versusplane wave tbermoacousticengines: Which is modulatingthe temperature with a high-powerlaser. Parametric drives are best? W. PatrickArnott (AtmosphericSci. Ctr., DesertRes. Inst., P.O. promisingsince the drive mechanism is distributedover the entire volume Box 60220, Reno, NV 89506}, Jay Lightfoot,Richard Raspet,and HenryE. Bass (Univ.of Mississippi,University, MS 38677) of gasand becausethe responsemay becomelarge before saturation oc- curs.Although it is demonstratedthat laserdrive is not attractiveas a Most previouswork in thermoacousticshas consideredplacing the practicalmeans of high-powerdrive for longitudinalresonators, much elementsin planewave resonators. The lowestradial or breathingmode of interestingphysics has beenconsidered in the analysisof the proposed a cylindricalresonator is also potentiallyuseful for producingthermo- systemand will be discussed.[Work supported by ONR.]
3221 J. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128th Meeting:Acoustical Society of America 3221
Downloaded 27 Jun 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, 28 NOVEMBER 1994 SABINE ROOM, 1:30 TO 6:15 P.M.
SessionlpAO
AcousticalOceanography: Moderate-to-High FrequencyInversions for SedimentProperties
Darrell R. Jackson,Chair Applied PhysicsLaboratory, University of Washington,Seattle, Washington 98105
Chair's Introduction--l:30
Invited Papers
1:35
lpAOl. Three-dimensionalvelocity fluctuation structure of the seabedimaged by high-frequencycrosswell tomography. TokuoYamamoto (Appl. Marine Phys. Div., RSMAS,Univ. of Miami, Miami, FL 33149)
High-resolutionimages of the compressionalwave velocity fluctuation structure of the seabedare inverted from the traveltimes measuredby high-frequency(1-50 kHz) crosswellacoustic tomography experiments at threedifferent sites in shallowwater. The three-dimensionalpov•er spectra of thevelocity fluctuations are determined from the velocity images. The velocityfluctuation spectra are anisotropicin general,i.e., the fluctuationfrequency in the verticaldirection is muchhigher than in the horizontaldirection. The aspectratio of the two rangesfrom 4 to 10. In addition,the majorand minor axes of anisotropyare oftentilted from thevertical and the horizontaldirection. The angleof tilt, calleddip, is foundas largeas 30ø . The intensityof the fluctuationspectrum depends on the sedimenttype. These parametersof the three-dimensionalpower spectrumaffect the scatteringof acousticwaves. The strong dependenceof acousticbackscattering on the grazingand azimuthalangle observed by Jacksonand Briggs(1993) is excellently predictedwhen the anisotropyand the dip structureof the velocityfluctuations are incorporatedin an analyliealmodel of scaltering by sedimemvolume fluctuation (Yamamoto, this meeting). [Work supported by ONR.]
1:55
lpAO2. FM sonarcharacteristics for normal-incidencesediment classification. Steven G. Schockand Lester R. LeBlanc (Dept. of OceanEng., Florida Atlantic Univ., Boca Raton, FL 33431)
The predictionof sedimentproperties from normal-incidence acoustic measurements made with a broadbandsub-bottom profiler requiresthat several acoustic parameters be estimatedfrom the reflectiondata using independent numerical techniques to reducethe largepotential errors of any oneparameter. Examples of acousticparameters that are combined emplrically to estimatethe vertical profilesof physicalsediment properties are acousticimpedance, interlayer volume scattering, and attenuation. From the analysisof normal-incidencedata collectedin many depositionalenvironments, the characteristicsof a quantitativesub-bottom profiler for estimatingimpedance and volume scattering include: (1) theacoustic bandwidth of thetransmitted pulse must be at least2 octfor the reliablemeasurement of signalphase from interlayerreflections; (2) thetwo-way transmission/reception beam should be a conewith a widthbetween 15 ø and20 ø at the 3-dB downpoints to ensurethat interlayer reflection amplitude to volumeand surface scattering noiseratios are at least6 dB (narrowerbeamwidths result in reflectionamplitude measurement errors from sensormotion or seafloor slopesless than 5ø); (3) thetransmitted pulses contain energy from 500 Hz to 10 kHz to ensuremost inletlayer impedance gradients can be accuratelymeasured.
2:15
lpAO3. Acousticprediction of sedimentimpedance. DouglasN. Lambert,Donald J. Walter (Naval Res.Lab., Code7431, Stennis SpaceCenter, MS 39529), WilliamR. Bryant,Niall C. Slowey (TexasA&M Univ.,College Station, TX 77843),and JohnC. Cranford (NeptuneSci., Inc., Slidell,LA 70458)
The Naval ResearchLaboratory has been developing a normal-incidence,high-frequency (15-30 kHz), narrowbeamwidth (6 ø- 12ø),high-resolution (>92-dB dynamicrange) seismic system with the capability to predict,in nearreal time, acoustic impedance of the upperseveral meters of the seafloorusing inversion techniques. Acoustic impedance, predicted in a seriesof ten selectabletime windows,is thenused to estimateother sediment properties through empirical relationships. A series of groundtruth sediment cores havebeen collected along a seismictrackline in the southwesternBaltic Sea with sedimenttypes varying from glacialtill to soft, methanegas-charged clayey silts. Comparison of the high-resolutionseismic data to sedimentstructure determined from the cores s•owsexcellent correlation for both15- and30-1cHz data. The comparisonof laboratory-measuredsediment geotechnical properties andacoustically estimated properties shows good correlation in thesurficial sediments and somewhat less correlation with depthin the sediments.Since gas bubbles within the sediment are strong acoustic reflectors at thesefrequencies, the use of standardalgorithms for nongassysediments can lead to overestimationof predictedimpedance values.
2:35
lpAO4. Measurementsof relativebottom backscattering strength by a digital sidescan sonar. GuntherFechner and Ingo H. Stender (Forschungsanstaltder Bundeswehrffir Wasserschall-undGeophys., D-24148 Kiel, Germany) A conventionalside scan sonar gives only a qualitativeimage of seafloorbackscatter distribution. It doesnot allow quantitative measurementsof the bottom backscattering strength. Because of theadvantages of the side scan sonar (imaging and profiling capacity
3222 J. Acoust.Soc. Am., Vol. 96, No.5, Pt. 2, November1994 128thMeeting: Acoustical Society of Amedca 3222
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp andeasy handling), a conventional100-kHz side scan sonar was redesigned. Signal generation and transducers remained unchanged. The receivedraw signalis amplified,digitized at 20 kHz, andstored on a 486 personalcomputer. Data are displayedas colorcoded imageson screen and hard copy. Attenuation with distanceand angle dependency {using Lainbert's law) arecompensated. This digital attachmentprovides relative backscatter data. On themuddy seafloor of theCBBL/JOBEX experimental site in EckernffrdeBay the digitalside scan sonar shows a ratheruniform bottom with low backscattervalues. The spatialvariation is lessthan 8 dB, mainly causedby Irawl markson thebottom. But insideone pockmark the backscatter strength varies as muchas 28 dB. This highvariation cannotbe attributedto sedimentchanges; all sedimentsamples inside the pockmarkwere mud.The strongbackscatter is presumably causedby the gassylayer inside the pockmarkwhich nearly coincides with the water-sedimentinterface.
2:55
1pAdS. Acousticcharacterization of marine sediments:State of the art. AnatoliyN. Irakin (N. N. AodreevAcoust. Inst., Shvemika 4, Moscow 117036, Russia)
A reviewof recenttheoretical and experimental investigations of soundscattering from the seafloorand analysis of methodsfor remoteacoustic characterization of marinesediments are presented.For narrow-bandsignals, echo characteristics have explicit relationships(in somesimple cases they are known) to thereflection and scattering coefficients, which can be relatedin turnto the materialparameters of themedium and used for determinationof bottom properties. For wideband signals, the relations between the medium and conventionalecho characteristicsare not so evident. Moreover, one must introduceother characteristics,such as the two-frequencyscattering function. Methods for the determinationof bottomparameters in thiscase are notsufficienfiy studied up to now,but someadvantages of widebandsignals can be usedsuch as theirhigh spatial resolution and the possibility of theiranalysis in the time-frequencydomain. The secondaspect of the problemis connectedwith modelingthe processof soundinteraction with differentbottom media. Severalgeoacoustic models for moderateto high frequenciesare considered,taking into accountregular sedimentstratification and different types irregularity: roughness of the interfaces,volume inhomogeneities, and discretescatterers.
3:15-3:30 Break
ContributedPapers
3:30 with the AcousticSediment Classification System (ASCS). The results indicatethe ability to resolvereflecting horizons and determine the imped- lpAO6. Correlationof acousticimpedance and volume scattering ance of the sediment surface and subsurface. with sedimentmean grain size and bulk density. Darryl L. DeBruin, LesterR. LcBianc,and Steven G. Schock(Ctr. for Acoust. and Vib., Dept. of OceanEng., Florida Atlantic Univ., 500 NW 20th St., BocaRaton, FL •33431) lpAOS. Simultaneous reconstruction of velocity structure and Usinghigh-resolution sonar data, a rulebase classifier model is devel- boundary geometry in crosshole tomography. SubramaniamD. opedto correlateacoustic impedance and volume scattering with sediment Rajah,Henry Laible, and Cynthia 1. Sellers (WoodsHole Oceanogr. Inst., meangrain size and bulk density.The acousticimpedance is invertedfrom WoodsHole, MA 02543) the impulseresponse of the sonardata and the scatteringstrength is cal- culatedbetween detected layers using a scatteringmodel. Synthetic data In recentyears, crosshole tomography has been used to infer the ve- and fielddata are usedto demonstratethe high-resolutionlayer detection locitystructure in theearth's interior, ocean sediments, and in seaice. in all method,based on a local least-squaresfit, that extractsthe impulsere- cases,velocity estimates were obtainedfrom travel time data for the ear- sponseof the acousticdata. This analysisis heuristicallyconstrained to liestarrival. In manyinstances, the field measurementscontain not only the estimate solutions within the resolution bounds of the sonar data. The informationabout this directpath but alsoabout paths that have interacted classifieruses historic measurements, empirical relations, and fuzzy set with Ihe boundaries. If one were to use the information contained in such theory to build the rule base model that is usedto correlatethe acoustic boundaryreflected paths, the resolutionof the estimatescould be consid- propertieswith sedimentmean grain size and bulk density.Comparisons erably improved.This, however,implies that one knows the boundary betweenestimates of meangrain size and bulk densityfrom the rule base geometry,which is generallynot the case.An approachthat one can take classifiermodel analysisof actualsonar data and geotechnicalmeasure- is to jointly estimatethe boundarygeometry and the velocitystructure in mentsare madein variousdeposittonal environments. The sonarand core the material.Different approaches that can be usedto implementthis idea data were acquiredin Kiel Germanyin collaborationwith the Coastal andevaluate the methodusing synthetic data and field dataare presented. BenthieBoundary Layer researchteam. [Worksupported by ONR.]
3:45 4:15
lpAO7. The characterization of near-surface sediments with 1pAd9. Determination of physical properties of a porous seabed high-frequency acoustic pulses. JamesA. Hawkins, Warren T. Wood, from reflection amplitude data by using the genetic algorithm. DouglasN. Lambert,and Donald J. Walter (Naval Res. Lab., Stennis Altan Turgut (Inst. of Marine Sci., METU, P.O. Box 28, Erdemli-Icel, SpaceCenter, MS 39529-5004) Turkey) Thedegree to which surficial and subsurficial (5-10 m) sedimentprop- A globaloptimization technique, the geneticalgorithm, is effectively ertiescan be determinedfrom their acousticresponse to high-frequency usedfor the inversionof seabedproperties from plane-wavereflection (15-30 kHz) sbort-dumtion(0.1-0.3 ms)acoustic pulses has been inves- data.The seabedis modeledas a porousviseoelastic medium using Biot's tigated.The acoustic response of thesediment (echo) is assumedto be the theoryand the plane-wavereflection coefficient is calculatedusing the convolution of the source pulse with the first several meters of tile sedi- analyticalexpresstons derived by Stoll and Kan [J. ACOUSt.:•OC. Am. 70, ment representedin the time domain by a series of impulsesfor each 149--156 {1980)]. A sensitivityanalysis indicated that the plane-wavere- reflectingsurface. The impedancefor eachis thendetermined with a stan- flectionshows strong dependency on theporosity, permeability, and shear dard aleconvolutionalgorithm. The problemis first approachedusing a modulusof the seabed.Inversion of these parametersis primarily at- syntheticearth model. The algorithmis nextapplied to fielddata collected temptedby assigningrepresentative values to otherBlot parameterswhich
3223 J. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128th Meeting:Acoustical Society of America 3223
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp have secondaryeffects on the plane-wavereflection coefficient. Fast/slow Traykovski,James Lynch, James Irish, and Arthur Newhall (WoodsHole compressionaland shear-wavespeeds, and densityof the seabed,are also Oceanogr.Inst., WoodsHole, MA 02543) calculatedusing the invertedporosity, permeability, and shear modulus. An experimentaltechnique by usinga towedarray and chirp signalsis also The bottomboundary layer (BBL) is of greatimportance in oceanog- discussedfor effectiveand rapidsurveying of the seafloor. raphy as it determinesthe amountof frictionalstress a flow encounters from the oceanbottom, and it playsa majorrole in controllingsediment 4:30 transportprocesses. The backscatterof acousticalenergy from suspended sedimentshasproven tobe a valuabletool in studying theBBL. Prelimi- lpAO10. A structure function constraint for stable least-squares nary resultsfrom acousticalmonitoring of sedimenttransport at the inversionof reflectiondata. KennethE. Gilbert,Timothy J. Kulbago, "Long-TermEcosystem Observatory" (LEO-15) site located in 15 m of andP. JasonWhite (Appl.Res. Lab. and the GraduateProg. in Acoust., wateroff of the southernNew Jerseycoast are presented.The acoustical PennState Univ., P.O. Box 30, StateCollege, PA 16804) backscattersystem that was deployedat this site duringthe winterand High-frequencyseismic profiles often indicate that the near-surface springof 1994 is capableof profilingthe entirewater column by usinga sedimentsin shallow water are layeredon scaleslarger than about0.5 m downwardlooking 5-, 2'.5 -, and1-mI-Lz sonors and a 1-mHzupward look- but not on smallerscales. Consequently, for a meaningfulleast-squares ing sonar.The fine resolutionimages produced from this systemresolved inversionof reflectiondata using a horizontallystratified sediment model, severalsediment suspension events and bottom feature movementwas the wavelengthsin the insonifyingwave shouldbe long enoughto "aver- observed.[Work supported by NOAA.] age out" the small-scalesediment structure. With sucha finite wavelength inversion, the sedimentmodel must include some resolutionconstraints in orderto yield a stableinversion. A commonapproach, for example,is to 5:15 considera stackof homogeneouslayers where each layer is thickerthan, say,a quarterof a wavelength.An alternativeconstraint method based on lpAO13. The continuousspectrum and ambient noiseinversions in a smacturefunction or, equivalently,an autocorrelationfunction, is pre- shallow water. Nicholas M. Carbone, Grant B. Deane, and Michael J. sented.It is shown that with a structurefunction constraint,a stable inver- Buckingham(Marine Phys. Lab.-0238, Scripps Inst. of Oceanogr.,9500 sion is obtainedeven if the layeredstructure approaches a continuous Gilman DL, La Jolla, CA 92093-0238) pr9file. Without the constraint,the inversionbecomes meaningless as a continuumis approached.[Work supported by NRL andONR.] It has been demonstrated that the ambient noise field in the ocean over continentalshelf regions contains sufficient environmental information to 4:45 allow for inversionof the geoacousticparameters of the seabed.In past studiesboth compressionaland shearwave speedshave been obtained lpAOll. Interpreting and extracting sediment attenuation from whichare in goodagreement with measurementsmade using independent measuredbottom loss data in the frequency range 500-5000 Hz. methods. Other factors which affect the coherence and influence the noise CharlesW. Holland,Greg Muncill, and Peter Neumann (Planning Syst., inversionsfor basementparameters include the sea state and sound-speed Inc., 7923 JonesBranch Dr., McLean, VA 22102) profile.We haveobserved that for low seastates, the ambientnoise field containslittle or no contributionfrom thecontinuous spectrum. Theoretical The angleof intromissionis the angleat whichthere is totaltransmis- studies,on theother hand, indicate that the effect of thecontinuous spec- sion acrossan interface.This phenomenaoccurs between two ideal (loss- trumis significantfor softseabeds. One explanationfor its absenceis that less)half-spaces when the sound speed in thetransmitting medium is lower at low sea states there are few surface acoustic events close to the obser- and the densityhigher than in the incidentmedium. In low-energyenvi- vationpoint, implyingthat the standardstatistical model used to calculate ronments(i.e., whereclay and silty-claysediment types dominate) the the coherenceis not valid for overheadsources. The densityof surface angle of intromissionis often observedin measuredbottom loss data. The acousticsources in relationto the spatialstructure of the ambientnoise lossat and aroundthe angleof intromissionis observedto be a strong fieldwill be explored.[Work supported by ONR.] functionof attenuationin thehost medium as well asthe effects of gradi- ents,random sedimentary layering, discrete sub-bottom reflecting hori- zons,roughness, and volume inhomogeneities. The physicalmechanisms controllingreflection near the angle of intromissionare explored in several 5:30-6:15 datasets to demonstratethe potentialfor invertingthe measureddata for attenuation.[Work supported by theONR/AEAS Program.]
PANEL DISCUSSION: 5:00 Panel Moderator: Darrell R. Jackson lpAO12. Acousticalmonitoring of sedimenttransport in the bottom Panel Members:Anatoliy N. Ivakin, DouglasN. Lambert,Steven G. boundary layer at the inner continental shelf LEO-15 site. Peter Schock,Ingo H. Stender,Tokuo Yamamoto
3224 J.Acoust. Soc. Am., Vol. 96, No. 5, Pt.2, November1994 128thMeeting: Acoustical Society of America 3224
Downloaded 27 Jun 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, 28 NOVEMBER 1994 SAN ANTONIO ROOM, 1:45 TO 5:00 P.M.
SessionlpPA
PhysicalAcoustics: General Topics
ChristopherL. Morfey, Chair Instituteof Soundand l•brationResearch, University of Southampton,Southampton SO17 1B J, UnitedKingdom
Invited Paper
1:45
IpPAI. Newfrontiers in molecularacoustics of liquids.Armen Sarvazyan a• (Dept. of Chem.,Rutgers Univ., New Brunswick, NJ 08903)
The majoraccomplishments in molecular acoustics of liquidsystems are summarized. The mostpromising direction in thisfield is acousticalthermodynamics. The possibilityof acousticalevaluation of thermodynamicparameters of liquidscomes from the fact thatcompressibility of the fluid is thesecond derivative of Gibbsfree energy on pressure. Changes of enthalpy,entropy, free energy, andtheir pressure and temperature derivatives (heat capacity, volume, expansibility, compressibility, etc.) can be calculatedfrom the pressureand temperature dependencies of sound velocity in thefluid by usingadditionally the data on the temperature dependencies of densityand heat capacity of thefluid at 1 atm.Another new area is related to the studies of theacoustic nonlinearity parameter B/A whichis a simplefunction of thepressure derivative of thebulk modulusand provides unique information on the characterof intermolecularforces in theliquid. In aqueoussolutions B/A issignificantly determined bythe structure of water in thehydration shell of thesolute. The state of theart in theinstrumentation formolecular acoustic studies ispresented. New types of acousticalresonators basedon the use of cylindricalstanding waves enabling one to makemeasurements in microliter volume samples will bedescribed. a•permanentaddress: Institute ofTheoretical and Experimental Biophysics, Russian Academy of Sciences.
ContributedPapers
2:15 Kirchhofftheory of diffractionby a blackscreen. The resultingline inte- gralfor thetransient acoustic pressure is evaluatednumerically to studythe lpPA2. Matching pursuits with differential operator dictionaries. shapeof thebeam emitted by thetransducer in its dependence on theshape WadeTrappe and Joseph D. Lakey (Appl.Res. Labs., Univ. of Texasat of the rim andto analyzethe resolvingpower of the transducerin ultra- Austin,P.O. Box 8029,Austin, TX 78713-8029and Dept. of Math.,Univ. sonicapplications. For a focusedtransducer with a circularrim, a closed- of Texas at Austin, P.O. Box 8029, Austin, TX 78712) formanalytic expression is derivedfor thetransient acoustic pressure on its This paperwill examinein brevity the matchingpursuit algorithm axis. These results serve as a check on the numerical results obtained for proposedby Mallatand Zhang, which yields an adaptivesignal decompo- the moregeneral cases. For all cases,the acousticpressure at the focus sitionthat may be usedto derivea phaseplane representation of a signal. admitsa closed-formanalytic representation. [Adrianus T. de Hoopper- Basedon theseideas, and motivatedby the applicationof waveletsto formedthis researchas a VisitingScientist with Schlumberger-DollRe- lineardifferential operators, a new numerical method for solvingdifferen- search,Ridgefield, CT.] tial equationsis proposedwhich is basedon performinga matchingpursuit algorithmin an operateddictionary. Using this new algorithm the nonho- 2:45 mogeneousHelmholtz differential operator with zeroand nonzero bound- ary conditionsshall be examined.A classicaldifferential equation arising IpPA4. Transientaxial solutionfor the reflectionof a sphericalwave from acousticsshall be presentedand solved using this new method.Re- from a paraboloidalmirror. MarkF. Hamilton (Dept.of Mech.Eng., sults are presentedfor the one-dimensionalcase, and the extensionto Univ. of Texas at Austin, Austin, TX 78712-1063) higherdimensions is examinedusing the conceptof tensorproducts to constructa dictionaryfor higherdimensional Hilbert spaces. A methodused previously [J. Acoust.Sec. Am. 93, 1256 (1993)] to derive a transientaxial solutionfor a sphericalwave reflectedfrom an ellipsoidalmirror is applied to the case of a paraboloidalmirror. The 2:30 incidentspherical wave is radiatedfrom the focusof the mirror.A solution lpPA3. Calculation of the transient acousticwave field emitted by a for the impulseresponse of the reflectedaxial pressureis obtainedin the focusedtransducer with an arbitrary rim. AdrianusT. de Hoop (Delft form h(z,t) = $(t- z/co) - he(z) 8[t - te(z)] - (co/zr)h w(z,t), where8 is the Dirac delta function,c o is soundspeed, z is axial distancefrom the Univ.of Technol.,Faculty of Elec.Eng., Mekelweg 4, 2628 CD Delft, The Netherlands),Smaine Zeroug, and Sergio Kostek (Schlumberger-Doll baseof the mirror,z• is distanceto the focus,h e is therelative amplitude Res.,Ridgefield, CT 06877-4108) of theedge wave, t e its relativetime of arrival,and h w is thewake. Simple expressionsare obtained for he andh•. Beyondthe focus, the geometrical Closed-formanalytic expressions are derivedfor thetransient acoustic acousticsresult he-(l+d/zr) -• isrecovered forthe edge wave, where d is wave field emittedby a focusedtransducer with an arbitraryrim. The themirror depth. In thefar field,h,• becomesa deltafunction, the impulse radiatingpart of the transduceris a sphericalsurface bounded by a simply responsereduces to h(z,t)--(2zr/Coz)ln(lq-d/z•)$2 • (t-Z/Co), andthe de- connectedclosed curve of arbitraryshape. Starting from the Kirchhoff- rivative of the source waveform is thus obtained. Calculations for various Huygensrepresentation of the emittedacoustic wave field, the expression sourcewaveforms are presented.Related measurements are discussedin for the acousticpressure is transformedinto a line integralalong the rim of thefollowing presentation by Gelinet al. (PaperlpPA5). [Work supported the transducerby employingthe Maggi-Rubinowicz transformation in the by ONR.]
322,5 d. Acoust.Sec. Am., Vol. 96, No. 5, Pt. 2, November1994 128th Meeting:Acoustical Society of America 3225
Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 3:00 thatoccur in theserepresentations satisfy a recurrencescheme, which is well suitedfor implementationin a symbolicmanipulation program. The lpPA5. Experimentalstudy of reflectionof airborne, spark-produced transformdomain WKBJ asymptotic representations are analytically trans- N waves by a paraboloidal dish. Lawrence J. Gelin, Jamie M. formedback to the space-timedomain with the aid of the Cagniard-De Shorey,Daniel M. Hester,and David T. Blackstock(Appl. Res. Labs. and Hoopmethod. Numerical results for severalconfigurations with an intri- Mech. Eng. Dept., Univ. of Texasat Austin,P.O. Box 8029, Austin,TX cateloss behavior are presented. 78713-8029)
An experimentalinvestigation of the transientresponse of a paraboloi- 4:00 dal reflectoris reported.An inhomogeneousplane N wavewas produced by locatingan electricalspark at the focusof a machinedaluminum pa- lpPA8. Dependenceof axial propagation modes on piezoelectric raboloidalreflector (focal lengthzv=5.08 cm, radiusa=10.80 cm). A coupling coefficients in a piezoelectric continuously twisted secondreflector (zv=5.17 cm, a =10.05 cm)was constructed by spinning structurally chiral medium (PCTSCM). Steven F. Nagle and a containerof epoxyat constantspeed and allowing it to cure.Peak pres- AkhleahLakhtakia (227 HammondBldg., Dept. of Eng. Sci. and sure P and arrival time were measuredacross the beam (fixed axial dis- Mechan.,Penn State Univ., UniversityPark, PA 16802) tancez measuredfrom the reflectorsurface, variable radial distancer) and along the axis. The range of measurementswas r•<80 mm and 20.74 The materialproperties of a piezoelectriccontinuously twisted struc- mm• 4:15 3:15-3:30 Break lpPA9. Elastic-constantdetermination of small, near-isotropic 3:30 crystalsusing resonantultrasound spectroscopy: New quasicrystal results. P.S. Spoor,J. D. Maynard (Dept.of Phys.,Penn State Univ., IpPA6. Extension of the Huygens-Fresnel principle to a virtual UniversityPark, PA 16802), B. Golding (MichiganState Univ., East space. MitsuhiroUeda (Intl. CooperationCtr. for Sci. and Technol., Lansing,MI 48824),and A.R. Kortan (AT&T Bell Labs.,Murray Hill, TokyoInst. of Technol.,O-okayama, Meguro-ku, Tokyo 153, Japan) NJ 07974) The quantitativedescription of diffractionstarted with Fresnel,who If a materialis very nearlyisotropic, quantifying the residualanisot- introducedthe interferenceeffect to Huygens'principle where diffracted ropymay be quitedifficult using methods such as pulsesuperposition or wavesare expressedby an integralof secondarywavelets over an opening neutronscattering, when only a smallsample is available.However, reso- in an opaquescreen. Although this diffraction formula is an approximate nant ultrasoundspectroscopy using piezoelectric film transducersallows one, it hasgiven precise estimation of wavesdiffracted by the opening. precise(<0.1%) measurementof elasticconstants even on very small Mostdiffraction phenomena arise from 3-D objects.However, attempts to (<0.25 rag),fragile samples. This is of interestin thestudy of icosahedral applythe diffractiontheory to 3-D objectsare unsuccessfulsince, in these quasicrystals,which should theoretically be isotropic,but haveclosely cases,the regionfor integrationof secondarywavelets cannot be deter- relatedphases which are crystalline. Results on severalsamples of quasi- minedclearly. In orderto explainthe diffraction by polyhedrons,a hypo- crystallineand cubic AlCuLi will be presented,and use of rotationsof the theticalobserver is assumedat an observationpoint and the Huygens- elastictensor and Monte Carlo styleerror simulationsto aid in the data Fresnelprinciple is extendedto a spaceseen by the observervirtually. In analysiswill be discussed.[Work supportedby NSF GrantNo. DMR- this virtual spacethe observercan see real imagesand mirror images 9306791and by ONR.] throughfacets of thepolyhedron and every point in real andmirror images is consideredas a centerof thesecondary wavelets. The newrepresentation 4:30 of soundfield diffractedby 3-D objectsthat satisfies both the wave equa- tionand boundary conditions is derivedby thisextension [J. Acoust.Soc. lpPA10. Measurementsof ultrasonicattenuation and soundvelocity Am. 95, 2354-2362 (1994)].The algorithmto obtainsolutions from this in a single crystal of (La•_xSrx)2CuO4. Hong Zhang, M. J. representationwill be discussedin detail. McKenna,Bimal K. Sarma,Moises Levy (Dept. of Phys.,Univ. of Wisconsin--Milwaukee,Milwaukee, WI 53201), T. Kimura,K. Kishio, 3:45 andK. Kitazawa(Univ. of Tokyo,Tokyo, Japan) lpPA7. Transientacoustic wave fieldsin continuouslylayered fluids Measurementsof the ultrasonicattenuation and sound velocity were withattenuation. Martin D. Verweij (Lab.of Elcctromagn.Res., Dept. madeat frequenciesof 32 and 87 MHz in a largesingle crystal of of Elec. Eng., Delft Univ. of Teehnol.,P.O. Box 5031, 2600 GA Delft, The (L%.925Sr0.075)2CuO4 (•4X4X4 mm3),which exhibits a sharp (AT•I K) Netherlands) superconductingtransition at 37 K. For longitudinalwaves propagating alongthe c axis,the sound velocity shows a sharpsoftening, Ao/v •100 The space-timedomain acoustic wave field in an isotropic,1ossy, con- ppm,concurrent with the sharpsuperconducting transition in the suscep- tinuouslylayered fluid is analyzedusing a methodthat employs a combi- tibilitymeasurements. Following this transition, the susceptibility exhibits nationof higher-orderWKBJ asymptoticsand the Cagniard-DeHoop a smalltail extending to 27 K, wherea smallersoftening, Ao/o •20 ppm, method of inversion. The loss behavior of the fluid is described with the has beenobserved in the velocitymeasurements. Accompanying the aid of generaltemporal compliance and inertia memory functions. The •100-ppmvelocity drop, there is a signaturein theattenuation; following continuouslayering of the mediummanifests itself in the acousticwave thisfeature, the attenuation changes as the temperature is decreased fur- speed,the densityof mass,and both memoryfunctions, which are inde- ther, with a small kink in the attenuation at 27 K. Additional results of the pendent,continuous functions of thevertical coordinate. After the appli- dependenceof the attenuationand sound velocity in externalmagnetic cationof forwardtransformations, higher-order V•CBJ asymptotic repre- fields,orientated in thea-b plane,will bepresented. [Work supported by sentations of the transform domain solution are derived. The coefficients 3226 J. Acoust.Soc. Am., VoL 96, No.5, Pt.2, November1994 128thMeeting: Acoustical Society of America 3226 Downloaded 27 Jun 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 S. Redher,and H. I. Herrmann,J. Phys.Lett. (Paris) 46, L585(1985)] and scalingtheories of brittlefracture. Measurements have been made with lpPAIL Observation of indiv'dual bond breaking events in uniformtensile stress and bending stress, with the lattercorresponding to precursors,cascades, etc. in the onsetand progressionof fracture. a phasetransition in thepresence of an externalfield. For samplesof the TianmingZhang, S. R. Savitski,and J. D. Maynard (Dept.of Phys.,Penn samewidth, the observationsare quiteconsistent, showing the effectsof StateUniv., UniversityPark, PA 16802} precursors,onset, progression, stress waves, crack arrest, and other inter- Experimentalmeasurements of fracture have been made using a wide estingphenomena. A significantdifference in precursorsfor the uniform bandwidth(10 MHz} transducerand a systemwith a relativelylarge bond andbending stress fields is observed,perhaps a resultof thedimensionaltry size,with the resultthat one is able to observeindividual bond breaking of the maximumstress field. [Work supported by NSF GrantNo. DMR- events.The data provide a directtest of "fuse"models [L. deArcangelis, 9306791and by ONR.] MONDAY AFTERNOON, 28 NOVEMBER 1994 TRINITY A AND B, 1:00 TO 5:00 P.M. SessionlpSP SpeechCommunication: Acoustic Analysis and Perceptionof Consonants(Poster Session) Harvey Sussman,Chair Departmentof Linguistics,University of Texasat Austin,Austin, Texas 78712 ContributedPapers All posterswill be on displayfrom 1:00 to 5:00 p.m. To allow contributorsan opportunityto seeother posters, contributors of odd-numberedpapers will be at theirposters from 1:00to 3:00 p.m.,and contributors of even-numberedpapers will be at theirposters from 3:00 to 5:00 p.m. Posterswill remainon displayuntil 12:00 noonon Tuesday. IpSPI. Perceptionof fricativessynthesized by higher-levelcontrol of informationabout which bands contain the abruptchange, the steady-state a Klatt synthesizer. David R. Williams (SensimetricsCorp., 26 qualityin the vicinityof the proposedlandmark, segmental duration con- LandsdowneSt., Cambridge,MA 02139) straints,and an articulatorycontinuity requirement. Tested on a databaseof continuousspeech recorded in a silentroom by maleand female speakers, Resultsof perceptualtests of fdcafivessynthesized using an acoustic- thelandmark detector is shownto performwell, with a 94% truedetection articulatorymodel [K. N. Stevensand C. A- Bickley,J. Pbonet.19, 161- rate and a 10% false detection rate. Most of the missed landmarks were 174 (1991)]are presented. Parameters of the modelpermit time-varying adjacentto reducedvowels. These promising results indicate that land- eomrolof vocal-tractshape (first four natural frequencies) and of glottal marksare robustlyidentifiable points in the speechwaveform and that a andoral cross-sectional areas. After computingair flow andintraoral pres- landmarkdetector as a frontend in a speechrecognition system is feasible. surevalues, KLSYN88 synthesizersource parameters are estimated using [Worksupported by NSF.] mappingequations. The currentstudy examines model predictions for in- tervocalic alveolar and labio-dental fricatives. Stimulus sets were con- IpSP3. Clear speechdoes not exaggeratephonetalc contrast. JohnJ. structedby varyingthe sizes of peakclottat opening (8-20 mm•) and Ohala (Dept.of Linguist.,Univ. of California,Berkeley, CA 94720) minimumoral constriction (4-16 ram2),and the rate of oralconstriction Structurallinguistics teaches that one of the principalproperties of nearclosure/release (4,16 cm2/s). Subjects labeled the synthetic fricatives speechsounds is beingdifferent from eachother: The essenceof a pho- as voicedor voicelessand rated the "goodness"of the stimulias exem- nemeis thatit is not any otherphoneme. In addition,many structuralist plarsof voicelessfricatives. As expected,stimuli with the smallestand theoriesof soundchange are based on notionsof preservationof contrast largestglottal openings were judged as voiced and voiceless, respectively. betweenphoneroes. From this one might expect that it shouldbe possible At intermediateglcttal opening values, voicing judgments were influenced to observespeakers' efforts at maintainingcontrasts in speech.One situa- by the relativesizes of the glottaland oral openingsand, to a lesserextent, tion where this would be expectedis in repeatedspeech, i.e., where a by oral constrictionrate. Goodnessratings of the stimuligenerally corre- speakerrepeats a wordafler receiving feedback that it hasbeen misappre- latedwith labelingjudgments. The resultsdemonstrate the robustnessof hendedas another similar word. This paper reports results of an analysisof speechsound categories generated in thismanner. [Work supported by suchrepeated speech samples of tenEnglish speakers when they produced NIMH.] 1 of 12 near-minimalsyllables (bayea• paid, bea•pea• be• pet, bia• bit, IpSP2. landmark detection for distinctive feature-basedspeech etc.)under two conditions:control and repetition (in responseto feedback r•_'ognition.Sharlene A. Liu (SpeechCommun. Group, Res. Lab. of thattheir initial productionhad beenmisunderstood as one of the other Electron.,Dept. of EECS,MIT, Rm.36-511, Cambridge, MA 02139) syllables).Contrary to expectations,there was no significantcontrastire exaggerationsin VOT or vowelduration as a functionof the wordpre- This work is a componentof a proposedknowledge-based speech sentedin feedback.[Work supported by AGT,Ltd.] recognitionsystem, which uses/andmarks to guide the search for distinc- IpSP4.The role of segment-internalrate informationin the phonetic tivefeatures. In anutterance, landmarks identify localized regions where classificationof stop consonants.Thomas Charles Bourgeois and theacoustic manifestations of the linguisticallymotivated distinctive fea- Kern/P.Green (Inst.for Neurogeo.Commun. Disord., Univ. of Arizona, turesarc mO•l •alicnt. An algorithmfor auiomalicallydetecting landmarLs Tucson,AZ 85721) implementedby abruptarticulatory movements is described.The algo- rithmis a hierarchicallystructured algorithm rooted in linguisticand pro- Duringthe course of a normalconversation talkers make frequent and ductiontheory. It looksfor abruptenergy changes in six frequencybands extensivechanges in speakingrate which affects the acoustic realization of and at two levelsof temporalresolution. Landmarks are foundbased on both consonants and vowels. Previous research has shown that the articu- 3227 J. Acoust.Soc. Am., VoL 96, No. 5, Pt. 2, November1994 128th Meeting:Acoustical Society of America 3227 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp lationrate of a syllableinfluences both the productionand phoneticcat- Presumablyas a resultof coarticulafion,/6/ often assimilatesto a egorizationof its segmentalcomponents. However, little certaintyexists precedingIn/ in phraseslike "win those,"but this assimilationis not regardingwhich portionsof the syllablecarry informationabout overall completefor all features.With respectto thefeature [nasal], the assimila- articulationrate. The presentstudy investigated this questionby editingthe tion is often radical. The entire consonantregion in the middle of the burstand aspiration phases from naturalfoi/and/pi/syllables produced at two-wordsequence is nasalized.However, acoustic evidence suggests that a fastrate of speech,and cross-splicing them onto the sametokens pro- contextuallynasalized/6/retains its dentalplace of articulation.Specifi- ducedat slow ratesof speech(and vice versa).These tokens were pre- cally,F2 is considerablylower at the releaseof a contextuallynasalized sentedto subjectsfor speededclassification of the initialconsonant. The 161than at the releaseof a true/n/, as would be expectedfor a dental resultsindicate that subjects were sensitive to themismatch in articulation consonant.Perception tests show that listeners can generally tell the dif- ratebetween the initialburst and aspiration of the stopconsonant and the ferencebetween natural tokens of pairslike "win nos" and ':win those," remainderof thesyllable created by thecross-splicing technique. Further evenwhen the/6/is completelynasalized. In addition,a syntheticstimulus investigationusing/bi-pi/continua created in a similarmanner indicates continuumwas constructed in whichitems differed only with respectto F2 thatconsonant-internal rate informationis usedduring phonetic categori- frequencyin the vicinity of the nasalconsonant regions of phraseslike zation of the stimuli. These results are discussed in the context of current "win nos." Listenerssystematically reported hearing "those" more often issuesof ratenormalization and speech perception. [Work supported in when F2 was low at the release of the nasal consonant. These results are partby Researchand Training Center Grant No. Pt0 DC-01409from the consistentwith the claim of Krakow, Fowler, and others,that listenerscan NationalInstitute on Deafnessand otherCommunication Disorders.] at leastsometimes factor out coarticulatoryeffects. [Work supportedby NSE] IpSPS.Cross-language tests of the perceptualmagnet efteel for/•/ and/1]. PaulIverson (Dept.of Speechand Hear. Sci., WJ-10,Univ. of IpSPS. Effect of fundaroental frequency perturbations on roedial Washington,Seattle, WA 98195), EugenDiesch, Claudia Sicbert (Tech. stop-consonant[voice] judgments. MichelleR. Mollsand Randy I• Univ. of Berlin, Berlin, Germany),and PatriciaK. Kuhl (Univ. of Diem (Dept.of Psychol.,Univ. of Texasat Austin,Austin, TX 78712) Washington,Seattle, WA) Previousresearch has suggestedthat the directionof short-duration fundamentalfrequency (F0) perturbationsfollowing consonants provides Recentexperiments by Iversonand Kuhl havesuggested that the per- a cueto consonant[voice] status. More recently, Silverman [Phonetica 43, ceptualorganization of the AmericanEnglish It/ and ,q/ categoriesis 76-91 (1986)]proposed that the [voice] cue is providedby thedirection slrongiyinfluenced by categorygoodness. American adult listeners exhibit and extentof F0 perturbationsrelative to the underlyingintonational con- a perceptualmagnet effect characterized by low sensitivityand perceptual tour.A competingview, the low-frequencyhypothesis, suggests that F0 clnsleringnear the bestexemplars of It/and/I/and high sensitivityand participatesin a moregeneral way wherebyany low-frequencyenergy in stretchedperceptual distances near the worst exemplars. The presentstudy theregion of theconsonant will contributeto theperception of a [+ voice] comparesthe responses of nativeGerman and English speakers to evaluate consonant.In thisstudy, 15 speechstimulus series, each ranging pereep- whetherthe representationof thesecategories is influencedby language tuallyfrom/aga/to/aka/, weresynthesized by varyingVeT from 10 to 45 experience.In separateexperiments, natural phoneroes of adultGerman ms in 5 ms steps.Fifteen different pitch contours were generated by des- (/a/ and/1/) andAmerican (/!/and/1/) speakerswere recorded,and syn- ignatingF0 targetsat threepoints in the stimulus:initial vowel, onseto{ thesizedAmerican English/t/and/I/tokens were identified, discriminated, voicingenergy after closure, and 100 ms after the onsetof voicing.Three rated for categorygoodness, and rated for similarity by both groupsof F0 valueswere used,arranged into two pairs:100 and 120 Hz and 120 and subjects.The resultsdemonstrate that German listenersprefer, produce, 140 Hz. The resultsindicated that the value of F0 at vowel onset, rather and have pemeptualclustering for/1/ phonemeswith a higherF2 fre- thanthe relativemovement of F0, is the bestpredictor of subjects'judg- quency than do American listeners.German listenersdo not perceive mentsof consonant[voice] status. [Work supported by NIDCD.] American/t/phonemesto be goodexamples of the German/P,/category, andGerman listeners also exhibit somewhat less perceptual clustering for IpSP9. 1)eveicinga/z/does not tenkean/s/. CarolineL Smith (Audio/ /J/ phoneroesthan do Americanlisteners. The resultsconfirm that the SpeechPath (126), WestLAVA Med. Ctr., 11301Wilshire Blvd., Los perceptualmagnet effect for/!/and/1/is determinedby languageexperi- Angeles,CA 90073 andDiv. of Headand Neck Surgery,UCLA Schoolof ence.[Work supported by NIH.] Medicine,Los Angeles, CA 90024) IpSP6. A locus equation study of syllable-final stop place of It is well known that voiced stopsin Englishtend not to be fully articulation. Harvey M. Sussman (Dept. of Linguist.and Speech voiced.For manyAmerican speakers, voiced fricatives may alsohave little Commun., Univ. of Texas,Austin, TX 78712), JadineShore, and David or no voicing.In what phonelogicalcontexts do speakersdevoice under- Fruchler (Univ. of Texas,Austin, TX 78712) lying/z/?Previous research IT. Veatch,Ling. Sec. Am. mtg.,69 (1989)] emphasizedthe influenceof the followingsegment. The presentstudy Syllable-finalstops have differentcoarticolatory and perceptualprop- confirmsthis, and investigatesthe likelihoodof devoieingin different ertiescompared to syllable-initialstops. Locus equations have previously positionsin syllable,word, and sentence.Five speakersof AmericanEn- been usedto acousticallycharacterize place of articulationfor initial stop glish recordedmultiple repetitions of sentencesin which/s/and/z/oc- consonants[H. Sussman,H. McCaffrey,and S. Matthews,J. Acoust.Sec. curredin matchedenvironments. Measures of acousticdurations, airflow, Am. 90, 1309-1325 (1991) andH. Susaman,K. Hoemeke,and F. Ahmed, andvocal fold vibration as evidencedby EGG wereused to comparethe $. Acoust.Sec. Am. 94, 1256-1268(1993)]. Since locus equations also productionof/z/and/s/. Preliminary data from one speaker show a variety encodedegree of coarticulation,they might also provide an adequatepho- of/z/'S, with the durationof vocalfold vibrationsas a percentageof neticdescription of VC eventsfor finalre/,/d/, and/g/followingvaried fricativeduration ranging from 0% to 100%.However, the acoustic vowel vowelcontexts. Each of tenspeakers, five maleand five female,produced lengthdifference preceding/s/and/z/is maintained, and even those tokens threerepetitions of 90 CVC tokens.For eachfinal stop (Fo,d,gD there were of/Z/ in which there was no vocal fold vibration have r•duo_ed airflow ten medialvowels and three initial consonan•Vb, dVb, gVb, bVd, comparedto matchedtokens of Is/, suggestingthat alevoiced/z/may differ dVd, gVd, bVg, dVg, gVg. Three pointsalong the secondformant were from underlyingIs/ in glottalconstriction or level of puimonieactivity. measored•F2 onset(Hz), F2 midvowel(Hz), andF2 offset(Hz). Offset [Worksupported by NIH.] locusequations (VC) weregenerated for eachsyllable-final stop place, both across initial consonantal contexts and as a function of each initial lpSPI0. Spectral discontinuities and the vowel-length effect. stop.In addition,3-D plotswere generatedto determinehow F2 onset(x), AndrewJ. Lotto,Keith R. Kluender,and Loci L. Holt (Dept.of Psychol., midpoint(y), and offset(z) couldacoustically capture and differentiate Univ. of Wisconsin,Madison, Wl 53706) lexicalcontrasts. [Work supported by NIDCD.] Perceptionof thevoicing contrast in CV syllablescan be affectedby IpSP7. Speakersnasallze /• if it is precededby In/, but I'steners the durationof the followingvowel such that longer vowels lead to more don't care---They still hear /6/. SharonY. Manuel (Res. Lab. of "voiced"responses. On thebasis of severalexperiments, Green, Stevens, Electron.,Mass. Inst. of Technol.Bldg. 36-511, Cambridge, MA 02139) andKuhl [Percept. Psychephys. 55, 249-260(1994)] concluded that con- 3•28 J. Acoust.Soc. Am., Vol. 96, No.5, Pt.2, November1994 128thMeeting: Acoustical Society of America 322• Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp tinuityof pitch,but not continuityof fermentstructure, determined the he still couldnot produceAmerican Irl, probablydue to restrictedmove- effectivelength of the followingvowel. In attemptsto replicatethese mentof his tongue.Fine controlof Ihe tonguebody and pharyngealnar- findings,it was foundthat botheffects were highlydependent upon par- rowingare necessary for productionof/rL SR exhibitedrestricted vertical ticularchoices of pitch and formantvalues. First, discontinuityin pitch movementof the tonguebody due to a bandedtongue base and restricted doesnot precludethe vowel-lengtheffect when fundamentalfrequency posteriormovement of the tonguebody and rootdue to enlargedtonsils. changesfrom 200 to 100 Hz and 200-1-1zpartials extend continuously Surgery(tonsillectomy, adenoidectomy, and frenuloplasty) was indicated throughtest syllables.Second, spectral discontinuity does preclude the for reductionof SR's ocelusivesleep apnea. By hypothesis,these proce- vowel-lengtheffect when formant changes result in a spectralpeak moving dureswould also alleviateany physiologicalbasis for SR's inabilityto to anotherharmonic. Even when perceived identity of thevowel remained produceIt/. Recordingswere madeof multiple repetitionsof/r/ in 16 constant,formant changesthat resulted in a change in peak harmonic phonelogicalcontexts on two occasionsbefore surgery. Two morerecord- precludedthe vowel-lengtheffect. Yet, changesthat did not changepeak ingswere madeafter surgicalrecovery. {If SR doesnot developIrl after harmonicand did changeperceived vowel identitydid not precludethe surgicalintervention, additional recordings will be made after further vowel lengtheffect. Taken together, the resultsindicate that neitherpho- speechtherapy.) Acoustical analysis of theserecordings documents SR's netalccontinuity nor talkercontinuity, per se, is criticalto the vowel- developmentof Irl, andthe efficacy of surgicalintervention on hisspeech. lengtheffect. [Work supported by NSFand NIH.] lpSP14. Postvocalicconsonant clusters in Swedish. Peter E. Czigler lpSPll. Self-organizing maps of stop consonant place from (Umeaa University,901 87 Umeaa, Sweden)and Dawn M. Behne token-levellocus equation inputs. JoriHilbert (Dept.of Camput.Sci., (Univ.of Trondbeim,7055 Dragveil,Norway) Univ. of Texas, Austin, TX 78712), David E. Fruchter, Mona MeWilliams,Joseph Sirosh, and Harvey M. Sussman (Univ. of Texas, In Swedisha postvocalicconsonant is phonelogicallylong followinga Austin, 'IX 78712} distinctivelyshort vowel and phonelogically short following a distinctively long vowel. Previousresearch has demonstratedthat this distinctionis Previously[D. E. Fruchter,J. Acoust.Sec. Am. 95, 2977 (1994}], reflectedin the relativedurations of the correspondingsegments. In addi- identificationcurves were estimaled for English/b,d,gtusing synthetic CV tion, it has been shown that a consonant tends to be shotlet in duration stimuli comprehensivelysampling the F2-onset X F2-vowel acoustic whenit occursin a consonantcluster than when it is a singleconsonant. spacein the vicinity of Sussman'sfo,d,g/locus equations. These results However, when a consonantoccurs in a cluster,it becomesless obvious wereused to delineate"identification surfaces" situated in locusequation whetherit is a shortor long consonant.The goal of this projectis to space.The currentresearch uses a biologicallyplausible neural network determinewhether the short-longdichotomy of consonantsis acoustically (the Kohonenalgorithm} to modelthe aboveperception results. This al- realizedin clusters.Target words were identifiedin which /k/occured gorithmis an abstractionof the local, unsupervisedmap-organizing pro- occurred in four different codas structures:C, C:, Cs, and sC. Native cess thoughtto occur in the brain. The Kohoncomap forms a two- speakersof Swedishproduced the target words in carriersentences and the dimensionalrepresentation of stopconsonant place categories from F2- durationof theclosure of/k/and thepreceding vowels were measured. The onsetand F2-vowel inputs.This emergentrepresentation corresponds well resultsdemonstrate that the structureof a consonantcluster and ils neigh- with the experimentallyobserved identification surfaces and can be usedto boringsegments can affect the durationof a postvocalicconsonant. These classifynovel inputsand predictphoneme boundaries and confusability findingsare discussed in termsof syllable-internaltiming and the extent to regions. which consonant duration varies within clusters. IpSP12. Stimulus intensity and fundamental frequency effects on lpSPI5. Perteptual evidence of voicing assimilation in Russian. duplexperception. Houri K. Vorperian(Dept. of Commun.Disoral., MarthaW.Burton (415Moore Bldg., Dept. of Psychol.,Penn State Univ., tiniv. of Wisconsin-Madison,Madison, WI 53705), Marleen T. Oehs, UniversityPark, PA 16802) and KarenE. Robblee (PennState Univ., and D. WesleyGrantham (VanderbiltUniv., Nashville,TN 37232-8700} UniversityPark, PA 16802) The simultaneousperception of speechand nonspeechoccurs when the Previousresearch has provided acoustic phonetic evidence of voicing intensityof the F3 transitionof a threeformant synthetic syllable is in- assimilationin obstmentclusters across prepositional boundaries in Rus- creasedrelative to therest of thesyllable (the base). This phenomenon has sian[Burton et el., J. Acoust.Sec. Am. 95, 2875(A) (1994)].The current beeninterpreted as evidenceof a distinctsystem for speechperception that studyinvestigated whether native speakers of Russianperceive the initial precedesother specialized systems of generalauditory processing [Liber- consonantin obstruentclusters consistent with the claimsof voicingas- manand Mattingly, Science 243, 489-494 (1990)].Using F3 transitions similationor whetherthey show sensitivity to theunderlying voicing of the with fundamentalfrequencies different from thebase, and referencing their obstment.Obstmcot clusters that were at theboundary between a prepo- presentationlevels to the level at which eachF3 transitionwas barely sitionand a word were excisedfrom sentencesproduced by threenative audible in the context of the base, identificationfuoetions were obtained speakersof Russian.Listeners were presentedwith four fricative-stop acrossa wide rangeof F3 transitionintensities. As previouslydemon- combinations/zd,sd,zt,st/andfour stop-fdcativecombinations/dz, tz,ds,ts/ strated,results showed that the F3 transitionscontributed to the speech precededby 30 ms of an unstressedvowel and followed by 70 ms of a perceptover a wide rangeof intensitiesand fundamentalfrequencies. stressedvowel. Subjectsheard eight repetitionsof threetokens of each However,at very intenseF3 transitionlevels,/ga/identification decreased. clusterfrom each speaker. Results indicated that responses were consistent Also, bothIda/and/ga/identification progressively decreased as the fun- with thevoicing characteristics of the followingconsonant, not the under- damentalfrequency of the F3 transitionincreasingly differed from the lyingconsonant, supporting voicing assimilation. However, in the/zt/clus- baseand interacted with intensity.These findings indicate that information ters, therewere more voicedresponses than in the /st/clusters,which from generalauditory processing systems is availableto the specialized suggestssome evidence of incompletedevoicing of the fricative.Implica- speechperception system. The speechperception system tolerates a range tionsof the studyfor phoneticand phonelogical theories of speechwill be of informationfrom generalauditory processing systems before it rejects discussed. suchinformation as irrelevantto speech. IpSPI6. Acousticfeatures differentiatingKorean roedial tense and IpSPI3. Acousticevaluation of surgical interventionfor one speech lax stops. Ji-Hye Shin (Dept. of Linguist.,Univ. of Californiaat therapypatient. RobertHagiwara, Susan Meyers Fosoot (Phonel. Lab., Berkeley,Berkeley, CA 94720} U• Dept. of Linguist.,405 HilgardAve., LosAngeles, CA 90024}, David M. Alessi,and GeraldM. Sloan (ChildrensHospital Los Angeles, Much researchhas been done on the cues differentiatingthe three LosAngeles, CA 90054) Koreanstops in word initial position.This paperfocused on a more ne- gtecled area: Ihe acoustic cues Ot•ferentmUngthe medial tense anti lax The developmentof American/r/(characterizedacoustically by a low unaspiratedstops. Four adult Korean native speakers, two malesand two thirdformant} in onespeech therapy patient (SR, 6;6} after surgical inter- females,pronounced 16 minimalpairs containing these stops. The average ventionis documented.SR wasoriginally referred to speechtherapy for durationof vowelsbefore lax stopsis 93 mslonger than before their tense severalspeech disorders. Most were corrected in lessthan one year, though counterparts(143 ms for lax versus50 ms for tense).In addition,the 3229 J. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128th Meeting:Acoustical Society of Amedca 3229 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp averageduration of the stopclosure of tensestops is 178 ms longerthan averagedover ten repetitionsof the samesentence by the samespeaker. thatof lax stops(74 msfor lax versus252 msfor tense).These durational Resultsindicated that the spectrathus obtained were smooth,and they differencesare so large that they may be phonologicallydetermined, not revealedspectral changes over time moreclearly than those obtained by phonetically.Moreover, vowel durationmay vary with the speaker'ssex. eithertime averaging or ensembleaveraging alone. Further ensemble av- Femalespeakers have much shorter vowel duration before the lax stops. eragingacross different speakers was alsoexplored and hasproduced The qualityof voicing,tense or lax, is alsoa cueto thesetwo stoptypes, encouragingdata. [Work supported by NIH.] as it is in initialposition, but the relativeduration of the stopsand of the precedingvowel appearto be much more importantcues. The conse- IpSPI9. Ejectivesin Babine-Witsuwit'en.Katharine Davis (Dept.of quencesof theseresults for the phonologicaldescription of Koreanas well Speechand Hear. Sci., WJ-10 CDMRC, Univ.of Washington,Seattle, WA as the synthesisand automaticrecognition of Koreanwill be discussed. 98195)and SharonHargus (Univ.of Washington,Seattle, WA 98195) lpSP17. Hemispheric differencesin the perception of Zulu click Acousticproperties of ejectivesin an Athabaskanlanguage of British consonants.Robert A. Avery andCatherine T. Best (Dept.of Psychol., Columbiawere examined. Data from ten nativespeakers were recorded in WesleyanUniv., Middletown,CT 06459 and HaskinsLaboratories, New the field. FollowingHogan [Phonefica 33, 275-284 (1976)],prerelease Haven, CT 06511) closure,burst duration, voice onsettime, and postreleasesilent interval were measured.Following Ingram and Rigsby[Proceedings of the XIth Pastresearch has shown that speech sounds arc processedbetter by the InternationalCongress of PhoneticSciences, Telinn, Estonia2, 134-137 left hemisphere,nonspeech sounds by the righthemisphere, in mostright- (1987)],burst amplitude and the fundamental frequency of thefollowing handedpeople. To date,however, it is unknownwhether phonetic contrasts vowel were alsomeasured. Values were comparedwith thoseof homor- from an unfamiliarlanguage show this same pattern, and whether they are genienonejectives (voiceless unaspirated and voiceless aspirated). Prelimi- perceivedas speech.It is known that adults' perceptionof non-native nary resultsshow that the ejectivestops may be distinguishedfrom plain speechcontrasts is stronglyinfluenced by their languageexperience; thus aspiratedstops by VOT alone.Ejectives and plainunaspirated stops have non-nativecontrasts may be handledby differentprocesses than are native similarVOTs; the principaldifferences appear to occurin the vowel onset contrasts.Best et al. [JEP:HPP14, 345-360 (1988)] suggestedthat En- and in the prereleaseclosure phase. Strong ejective characteristics such as glish speakers'excellent discrimination of Zulu click consonantsoccurs thoseof Navajo[Lindau, J. Phonet.12, 147-155 (1984)]do notappear to becausethey hearthe clicksas nonspeech.Right-handed native speakers of be present.The presentfindings, combined with thoseof Ingram and Englishand of Zulu or Xhosaparticipated in a dichoticlistening study on Rigsby(1987) for thecontiguous but unrelated language Gitksan, imply cerebraldominance for perceptionof clicks in isolationand in/Ca/syl- that relativelyweak ejectivesmay be an arealphenomenon. Results will lables.Natural tokens of Zulu click consonantswere used (epical, lateral, also be contrastedwith publisheddata from the related languages and palat• placesof articulation,and voicelessaspirated, voiceless un- Chipewyanand Navajo. aspirated,and voicedcategories). Native speakers of Zulu and Xhosa showeda left hemispheredominance for discriminationof both the iso- lpSP20. Acousticcorrelates of manner of articulationfor Urdu stop latedclicks and/Ca/syllables, while nativespeakers of Englishde•non- consonants.Satmad Hussain (Speechand Lang. Pathol.,Dept. of stratedno suchhemispheric dominance. [Work supportedby NIH Grant Commun. Sci. and Disoral., Northwestern Univ., 2299 Sheridan Rd., No. HD-01994.] Evanston,IL 60208-3570) lpSP18. Combining time averaging and ensemble averaging in analyzing voicelessfricatives in Mandarin. Yi Xu and Lorin Wilde This studyinvestigates the acousticcorrelates for the four mannersof (SpeechGroup at Res. Lab. of Electron., MIT, 36-513 VassarSt., stoparticulation ([+-voice, +-aspirated]) at the four differentplaces of Cambridge,MA 02139) articulation(labial, dental, alveolar, and velar) in Urdu.The studyfollows upDavis' work [J. Phonet.22, 177-193 (1994)]on manner in thehomolo- The randomfluctuations and spurious peaks typically seen in fricative gousvelar stopsin Hindi. Data from four subjectsfor the 16 stops(ten spectracan be reducedby time averaging,i.e., averagingspectra obtained differenttokens of eachstop for eachsubject) support Davis' assertion that with overlappingtime windows over an interval of the frication noise. F2 "lag" time(between stop-released and onset of F2 for thefollowing Furthermore,token-to-token as well as individual speakervariations in vowel)is a moreconclusive measure for the feature[aspirated] than the fricativescan be reducedby ensembleaveraging, i.e., averagingover noise traditionalvoice onset time (VOT) measure.However in Urdu, unlike spectraof multipletokens in the samerelative time interval.However, for Hindi, lag time alonedoes not exhibita four-waycontrast. A measureof studyingcoarticulatory variation in thefrication noise, neither of thesetwo "lead"time (pre-stop-release voicing) is alsorequired. Thresholds for lead methodsalone is adequate:Time averagingdoes not handletoken-to-token time and lag time permit all four mannersto be distinguishedwithout and individualspeaker variations; ensemble averaging requires a large referenceto theplace of articulationfor all the subjects.Thus the phono- numberof tokensto producesmooth and consistent spectra. In thepresent logicalfeatures [voice] and [aspirated] are more phonetically orthogonal in study,time averaging and ensemble averaging were combined in theanaly- Urdu than Hindi. The resultscontribute to the ongoingdebate on the sis of coarticulatoryvariation of fricativesin Mandarin.The size of the invarianceversus variability of acousticcues, and to the discussioncon- time-averaginginterval was 20 ms, and the size of the individualFFF cerningthe representations relating the phonological and phonetic levels of windowswas 8 ms. The time-averagedspectra were furtherensemble- speech. 3230 d. Acoust.Soc. Am., Vol. 96, No.5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 323• Downloaded 27 Jun 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, 28 NOVEMBER 1994 BALLROOM B, 1:00 TO 4:45 P.M. SessionlpUW Underwater Acoustics:Scattering and Noise Michael F. Werby,Chair Naval ResearchLaboratory, Code 7181, StennisSpace Center, Mississippi 39529 ContributedPapers l:OO Soundscattering by an air bubblein a boundlessfluid is an old clas- sicalproblem [i.e., R. Y. Nishi,Acustica 33, 65-74 (1975)]. If the air lpUWI. High-frequency forward scattering from Gaussian bubble is near, and stronglyinteracting with the surfaceof a liquid half- spectrum, pressure release, corrugated surfaces: Measurements of space,then the scatteringcross section (SCS) of the bubbleis quitedif- twinkling exponentsand the dependenceof the secondmoment on ferentfrom its value far away from the boundary.The exactsolution for distancefrom surfaceand pulse length. J. S. Stroud,P. L. Marston thisscattering problem is giventhat is valid for any incidencedirection of (Phys.Dept., Washington State Univ., Pullman,WA 99164-2814),and the(plane) sound waves, and for anybubble depth, obtained by themethod K. L. Williams (Univ.of Washington,Seattle, WA 98105) of images.This benchmarksolution is found by meansof the addition A singlerealization of a Gaussianspectrum surface (rms roughness 1.5 theoremsfor the sphericalwave functions.The resultingSCS contains cm, correlationlength 10 cm) was manufacturedout of Styrofoam.This contributionsfrom the interface,the bubble,and from its image,and it is surfaceprovided a pressurerelease, corrugated surface for an underwater, expressiblein termsof couplingcoefficients containing products of Wignet forward-scatteringinvestigation. Omnidirectional source and receiver were 3-j symbols.The formulationis illustratedwith manycomputed plots and usedin the frequencyrange of 100-300 kHz. Shortpulses were usedto it is finally extendedto the caseof a round,low-concentration cloud of allow isolation of individual contributions to the scattered field. These equal size bubbles,just beneaththe sea surface.This generalizationis individualcontributions were then classified using catastrophe theory [K. possibleby replacingthe individualbubble properties by thoseof an "ef- L. Williams, J. S. Stroud, and P. L. Marston, J. Acoust. Soc. Am. 96, fectivemedium" describing the bubble cloud just as was found earlier [i.e., 1687-1702(1994)]. The frequencydependence of the ruthhigher-order J. Acoust.Soc. Am. 85,541-554 (1989)].[Work supported by NSWC'sIR intensitymoments I,• wasmeasured and compared to predictions[M. V. Program.] Berry,J. Phys.A 10,2061-2081 (1977)] that I,,, is proportionaltok •,, (for m>2), wherev m is a twinklingexponent. Also, the dependenceof 12 on 1:45 distancefrom the surfacewas examinedat a single frequencyutilizing variouspulse lengths. It is knownthat far from a surfacethe wave field will IpUW4. Temporal responsecomparisons between model results and obeyGaussian statistics (12=2). For shortpulses, however, the statistics of measurements of forward-scattered waves from the sea surface. E. the wave field are stronglydependent upon individualreflections. For J. Yoerger (Naval Res. Lab., Code 7174, StennisSpace Center, MS longerpulses this is the casenear the surfacebut as one movesaway it is 39529) and SuzanneT. McDaniel (PennState Univ., StateCollege, PA) shownthat the Gaussianlimit is approached..[Work supported by ONR.] The underwateracoustic propagation path for the forwardscattering of 1:15 energyfrom the sea surfaceis treatedas a linear, time-varyingrandom communicationschannel in the applicationof the Helmholtz-Kirchhoff lpUW2. Acoustic scattering from a buoyant plume using an integralformulation of thisproblem. The modelused for datacomparisons antiparallelscattering geometry. John Oeschger (Dept. of Phys.,Univ. utilizesthe bifrequencysystem function F(o•,to') developed by McDaniel of RhodeIsland, Kingston, RI 02881)and LouisGoodman (Ocean and [IEEEJ. Ocean.Eng. 17, 216-221 (1992)]for thetemporal response from AtmosphericPhys. Div., Arlington,VA 22217) a rough surface.The data analyzedfor this work were obtainedfrom a shallow-waterhigh-frequency acoustic experiment conducted on the Baltic An examinationis made of the applicationof the far-field Born ap- Sea during May 1993. Acoustic data included measurementsof surface proximationto the caseof high-frequencyacoustic scattering from a ther- forward-scattering,surface reverberation, and direct-path intensities. These mally producedbuoyant plume using a multiplebistatic antiparallel scat- were made utilizing two large stationarytowers resting on the seafloor. teringgeometry. Initial resultsindicate the failureof the predictionsmade Each tower was equippedwith horizontaland vertical receivingarrays by the far-field Born approximation.Further theoretical development in- anchored7.6 m abovethe fiat bottomdepth of 30 m. Concurrentenviron- cludesthe higher-order terms (wavefront curvature) in thefar-field expan- mentalmeasurements including wave heights,sound velocity profiles, and sion to fully describethe scatteringprocess. The previouslysimple rela- samplecores were made.The resultspresented here are for the surface tionship,however, between the scatteredpressure field and the Fourier forward-scatteredmeasurements made at 20, 40, 60, and 90 kHz. [Work transformof thescattering field becomesgreatly complicated. The problem supportedby the Office of Naval Research,Program Element 61153N, is reducedby consideringuniform vertical advection of the scatteringfield with technicalmanagement provided by the Naval ResearchLaboratory, and by takingtime seriesmeasurements of the plume.The resultingpre- StennisSpace Center, MS.] scriptionrelates the complexacoustic data to the two-dimensionalFourier transformof the scatteringfield througha two-dimensionallow-pass filter function which includes the effects of the wavefront curvature terms and 2:00 the beam pattern.Data are presentedfor the caseof scatteringfrom an unstableplume. Results confirm the predictionsmade by theory. lpUW5. Modeling and analysisof three-dimensionalscattering from Arctic Ice features. TarunK. Kapoorand Henrik Schmidt (Dept.of OceanEng., MIT, Cambridge,MA 02139) 1:30 Interpretationof low-frequencyacoustic scattering data from Arctic Ice lpUW3. Sound scatteringby a single and by a cloud of air bubbles is facilitatedwith realisticmodels of the large-scalefeatures observed near the sea surface. G. C. Gaunaurdand H. Huang (Naval Surf. underthe ice sheet.Previous analyses have modeled these, for example,as WarfareCtr., White Oak Detachment,Silver Spring,MD 20903-5640) a hemisphericalprotuberance on an an infiniteplane. Here, the under-ice 3231 J. Acoust. Soc. Am., Vol. 96, No. 5, Pt. 2, November 1994 128thMeeting: Acoustical Society ofAmerica 3231 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp featureis modeledas a solidelastic sphere attached in the centerof a thin 2:45-3:00 Break elasticplate. The sphere is assumedto becompletely submerged in water while theplate is assumedto be floatingon water.The interactionbetween 3:00 theplate and sphere is characterizedin terms of equivalentcoupling forces and bendingmoments at the attachmentring which are determinedby lpUW8. Measurementsof the scatteringof soundfrom laboratory matchingthe kinematicsof thesphere and the plate at thejunction. At our breakingwaves. Pat B. Dandenault,Ali R. Kolaini,and Yi Mao (Natl. frequenciesof interest[karO(I)], the modeldemonstrates scattering of Ctr. for Phys.Acoust., Univ. of Mississippi,University, MS 38677) the spheremodes into the in-planeand out-of-planemotions of the plate. The resultsof a laboratoryexperiment to characterizethe backscattered A comparisonwill be made betweenthe scatteredfields from the free and soundfield from the bubble cloud generated by spillingbreaking waves are coupledspheres. The analyticalresults will alsobe comparedwith those described.Gravity waveswere generatedby a computercontrolled obtainedfrom the CEAREX89 scatteringexperiments conducted in the plunging-typewavemaker along the lengthof a 12.7-m-longchannel CentralArctic region with 1.8-lbSUS charges detonated at nominaldepths wherethey were made to breakin a 3.6 mX3.6 mx2.4 anechoictank. An of 800 ft. [Worksupported by ON'R,High Latitude Program.] underwaterF42A transducer with a specialparabolic reflector was used to generateincident bursts of soundranging from 15 to 40 kHz. Thisproce- durewas conducted in thepresence of breakingand nonbreaking gravity 2:15 wavesin orderto isolatethe acousticscattering strength of the bubble cloudsfrom surface roughness. Detailed measurements of the average void lpUW6. A studyon intensityfluctuations in forward scatteringfrom fraction of the bubble cloud at the instant the sound was incident were the sea surface. PeterH. Dahl andDonald B. Percival (Appl.Phys. made.These observations show that there is a significantincrease in back- Lab.,College of Oceanand Fishery Sci., Univ. of Washington,Seattle, WA scatteringstrength from the bubble cloud when compared to surfacerough- 98105) ness.The scatteringstrength of the bubblecloud, with an averagevoid fractionof 0.33%, is also shownto increaseas the incidentfrequency Fluctuationsin the intensityof soundforward scatteredfrom the sea approachesthe resonantfrequency of the individualbubbles in the cloud. surfaceare discussed. The dataoriginate from an experimentoff thesouth- A simpletheory will be givento predictsome of theseobservations. ern Californiacoastline using the researchplatform FLIP. Measurements were madeusing omnidirectional sources suspended from a sparbuoy 3:15 (tetheredto FLIP)and receivers mounted on FLIP's hull, with range vary- IpUW9. Modeling the azimuthal dependence of sea surface ing between500 and 1000 m. The frequencywas 20-50 kHz and the backscatterduring CST-7. JohnDubberIcy, Richard S. Keiffer (NRL roughnessparameter x=2kh sin 0 was >>1 (where k is acousticwave Code 7181, Stennis Space Center, MS 39529-5004), and Jorge number,h rmswave height,and 0 grazingangle); thus the measurements NovariM (PlanningSyst., Inc., Bay St. Louis,MS) representhigh-frequency, incoherent scattering in a singlesurface bounce channel.An oftenused statistical model for intensityfluctuations in such Theoperator expansion method is appliedto realizationsof 2-D rough- conditionsis the exponentialPDF, or its equivalentRayleigh PDF for nessmeasured during CST-7 in orderto probe the azimuthal dependence of amplitude.Examples are presented wherein the exponentialmodel fails a thebackscatter from time-evolving, non-fully developed seas which con- Lillieforsstatistical goodness-of-fit test. The Lillieforstest is usedfor this tainswell from distant surface wave sources. To usewave buoy measured purposebecause parameters of thedistribution are not known a priori.An datawithout extrapolation in frequency beyond the measured surface wave alternativeto the single-parameterexponential PDF is thetwo-parameter spectra,the measuredfrequencies examined will be limitedto 75 and150 gammaPDK Candidatevariables, based on seastate and acquisition ge- Hz. The modelinggoal will be to determinethat if surfacescatter was ometrythat are covariate• to thenature of intensityfluctuations, are dis- aloneresponsible for acousticbackscatter from the surface,could there be cussed.[Work supported by ONR Code321.] a measurableazimuthal dependence in the scatteringduring this experi- ment?Comparisons to someavailable measured azimuthal dependence will be shown. 2:30 3:30 lpUW7. Influence of statistical surface models on dynamic lpUW10. Stabilityof signalplus noisein performanceevaluation of scattering of high-frequency signals from the ocean surface. processingschemes. Jacob George and Ronald A. Wagstaft(Naval Res. ChristianBjerrum-Niese and Leif Bj•m• (Dept.of Indust.Acoust., Tech. Lab., Code 7176, StennisSpace Center, MS 39529) Univ. of Denmark,Bldg. 425, DK-2800 Lyngby,Denmark) The stabilityof signalplus noise and the mechanisms governing the combinationof signal and noise at thereceiver are reported. These ques- Temporalvariations of scatteringof high-frequency,monochromatic tionsbecome important in performanceevaluation of processingschemes signalsfrom the oceansurface has been studied numerically. In the high- whichare designed to enhancethe S/N ratio.Of specialinterest is thecase frequencydomain the dynamicscattering can be modeledby a coherence of a weaksignal combining with a relativelystronger noise. Even though functionof the scatteredpressure field, which is basedon the Kirchhoff thenonlinear interaction of soundby soundcontinues to be a hot topic integral;the surfaceroughness is describedby a spatialsurface spectrum [see,for example, P.J. Westervelt, "Answer to criticism of experimenton andthe surface motion is describedby thegravity-wave dispersion relation scatteringof soundby sound,"J. Acoust.Soc. Am. 95, 2865 (1994)],the [D. Dowlingand D. Jackson,J.Acoust. Soc. Am. 93, 3149-3157(1993)]. largelylinear effects governed by thesuperposition principle are of pri- Applyingsome modifications to this approach,the temporalcoherence maryimportance in the present application. Simple rules governing the functionis foundby numericalevaluation oI a doubleintegral. The time- combinationof signal and noise, obtained through analysis of experimental varyingscattering can be examined in thefrequency domain by thepower dataand model calculations, will bediscussed. [Work supported by ON'R, spectrum(the Fourier transform of thecoherence function). It is examined with technicalmanagement provided by NRL/SSC.] howa monochromaticsignal is shiftedand smeared in thefrequency do- mainby comparingcomputations for the Pierson-Moskowitzspectrum 3:45 (fora fullydeveloped sea) with computations forthe JUNSWAP spectrum (for fetch-limitedseas). The followingresults, among other issues, have lpUWll. Estimation of Arctic ice thickness from ambient noise. been obtained:As the fetch decreases,the surfacewaves become shorter, OlgaCheruets and J. RobertFricke (Dept.Ocean Eng., Cambridge, MA 02139) leadingto increasingfrequency shifting of the scatteredsignal. [Work sponsoredby the Danish TechnicalResearch Council and the EU/MAST An estimateof totalice mass in theArctic is an important parmeter for programme.] globalclimate studies, but thereare no directmeans for providingthis 3232 J.Acoust. Soc. Am., Vol. 96, No. 5, Pt.2, November1994 128thMeeting: Acoustical Society ofAmerica 3232 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp information.A surrogatemeasurement, spatial integration of icethickness, Meannoise properties, traditionally used for underwateracoustics sys- is beingpursued by severalgroups using active acoustic and electromag- temsanalysis, are notsuitable for evaluatingthe performanceof full spec- neticmethods. As a complementto theseefforts, the passiveestimation of trum processorsbecause they don't have sufficientspace/time/frequency ice thicknessusing ambient noise caused by thermaland mechanical stress resolution.A computermodel of the noisefield associatedwith breaking cracksin the ice sheetis focusedon. The acousticsignal received from surfacewaves has been developed in an attemptto addressthis need.Due propagatingstress cracks is theconvolution of an elementalfracture source to the localizedstructure of the breakingwave sources,the true ambient functionand the spatialdistribution function (array) of the propagating noisefield is inherentlydiscrete and an attempthas been made to include crack.This analytic result predicts a tonalspectral component of O (1 kHz) someproperties of the discretenature of the space-timenoise field in the that relatesdirectly to ice thickness.Experimental data collectedin the model.The modelcomputes a realizationof a time-delaybeamformed BeaufortSea during the springof 1994 demonstratesthe presenceof this representationof the acousticfield at a vertical array in a shallow-water spectralpeak, which correlates well with the measuredice thicknessat the site. environment,given somestatistical information about the noisesources. 4:00 The approachtaken is stochasticand semiempirical, incorporating recently obtainedexperimental data on the acousticcoverage (acoustic analog of lpUW12. Shallow-water ambient noise due to surf. Marc Stewart whitecapcoverage), duration, and sourcelevel distributionsassociated (CombatSyst. Sci. and Technol. Curriculum, Naval Postgraduate School, with individualbreaking waves (Farmer 1994). Sources are considered to Monterey,CA 93943), O. B. Wilson,J. H. Wilson,and R. H. Bourke radiateas dipoles,and the radiatedfields from the individualdiscrete (NavalPostgraduate School, Monterey, CA 93943) sources(breaking waves) are propagated to the array using a wave-number Forecastinglevels and directionalityof ambientnoise in the littoral integrationtechnique. [Work supported by ONR.] environmentis importantfor predictingperformance of acousticsensor systemsand developingnaval warfare tactics for that environment.Noise 4:30 dueto wavesbreaking at the beachcontributes significantly to the low- lpUW14. Effect of forward-scattered signal on beam noise frequencyambient noise in shallowwater, as shown by theobservations of O. B. Wilson, S. N. Wolf, and F. lngenito[J. Acoust.Soc. Am. 78, 190- estimationin shallowwater. YungP. Lee andJohn Hanna (Sci.Appl. 195 (1985)].At somegeographic points worldwide, unique geoacoustic Intl. Corp., 1710 GoodridgeDr., MS T1-3-5, McLean, VA 22102) featurescontribute to the detectabilityof "surf pointnoise" (a termcoined by submariners)dozens of kilometersout to sea.The objective of thiswork In deterministicsituations, adaptive processors resolve strong coherent is to applymore recently developed and powerful shallow-water propaga- interferersand eliminate their contribution at locationsaway from them. tionloss models and the increased knowledge of thegeoacoustic properties But, in operation,it is foundthat the beamnoise away from strong inter- of the seabedto obtaina quantitativeunderstanding of observationsre- ferersis affectedby theirpresence. Stochastic mechanisms involved with portedby O. B. Wilsonet aL, andto makepossible the prediction of the the interferer'ssignal are assumedto be responsiblefor thisbehavior. A noise fields from surf in other locations. The results of the use of the SNAP comparisonof oceandata with a simulationhas been made to illustratethe programsapplied to the MontereyBay environmentwill be presented. effectof theforward-scattered signal from the ocean surface on adaptive 4:15 beamnoise estimation in shallowwater. The stochastic forward-scattering mechanismis dependenton the environmentand its effectis apparently lpUW13. A semiempiricalmodel for breaking wave noise fields. influencedby undersamplingin the spatialaperture of the measurement StevenFinette and RichardHeitmeyer (Acoust.Div., Naval Res. Lab., array.The dependencyof beamnoise on waveheightand bathymetry have Washington,DC 20375) been observed. MONDAY EVENING, 28 NOVEMBER 1994 BALLROOM B, 7:00 TO 9:00 P.M. Session leID Interdisciplinary: Tutorial on Acoustic Cavitation: Sonic Effervescence AnthonyA. Atchley, Chair Departmentof Physics,Naval PostgraduateSchool, Monterey, California 93943 Chair's Introduction--7:00 Invited Paper 7:05 leID1. Acousticcavitation: Sonic effervescence. Robert E. Apfel (Ctr. for Ultrasonicsand Sonics,Yale Univ., New Haven,CT 06520-8286) Bubblesintrigue and amuseyoung and old, scientistand nonscientist,alike. When acousticalwaves either cause or enhancethe activityof bubbles,a varietyof phenomenacan be observed,ranging from sonoluminescenceto ultrasonic cleaning, and from acousticalattenuation in the oceanto microbubbleformation in blood.This tutorialwill review theseand other phenomena associated with acousticcavitation, focusing on the interestingbasic questions underlying the observationsand summarizingthe natureof the beneficialapplications that cavitation permits and the strategies for avoidingundesirable cavitation. In addition,points of contactwill be made with other bubble phenomena,such as boiling, hydrodynamiccavitation, decompression sickness, and radiation-induced bubbleformation in superheatedliquids (the bubble chamber). Participants in thistutorial should be ableto tell if theglass of beerthey aredrinking from is clean.(If possible,samples will be available...fortesting purposes.) 3233 J. Acoust. Soc. Am., Vol. 96, No. 5, Pt. 2, November 1994 128th Meeting:Acoustical Society of America 3233 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp TUESDAY MORNING, 29 NOVEMBER 1994 SABINE ROOM, 8:00 A.M. TO 12:35 P.M. Session 2aAO AcousticalOceanography: Acoustical Determination of Ocean Processes Michael D. Collins, Chair Naval ResearchLaboratory, Code 7140, Washington,DC 20375 Chair's Introduction---8:00 ContributedPapers 8:05 Preciseknowledge about environmental parametcrs is Mghly desirable for preciseacoustic modeling of the underwaterchannel. Simulations have 2aAOl. Efficient navigation of parameter landscapes. Michael D. shown that global inversionmethods such as simulatedannealing and Collins (Naval Res. Lab., Washington,DC 20375) geneticalgorithms are effective for theestimation of bothgeoacoustic and The covariancematrix of the gradientof the costfunction contains a geometric(source location, receiver locations, and waterdepth) param- greatdeal of informationabout a parameterspace. The eigenvectors of the eters.In thispaper genetic algorithms are appliedto acousticfield obser- covariancematrix form an optimal basis (in thesense of datacompression) vations. The field observations were collected at a shallow-water site in the for the gradient.Since search algorithms base their decisions on the gra- MediterraneanSea near the Italian coast,where the depthwas approxi- dient(often in an indirectfashion), the eigenvectors in some sense form an mately130 m. The sourcewas stationary and produced a broadbandsignal optimalset of generatorsfor navigatingparameter landscapes. For prob- at 170 Hz; a verticalarmy of receiverswhich spannedmost of the water lems involvinga long valley, thereis usuallyan eigenvectororiented columnwas employed.The inversionprocess used the Bartlettprocessor parallelto the valley.Search algorithms based on theoptimal generators for the objectfunction. A range-independentversion of the SACLANT- may find the deepestpoint in the valley severaltimes faster than algo- CEN normal-modeacoustic propagation model SNAe was used for forward rithmsbased on othergenerators. The covarianeematrix alsocontains modeling.Inversion was carried out simultaneouslyover sourcelocation informationabout the key underlying parameters. The most important pa- parameters,range and depth,and environmentalparameters. A 20-mix rameterscorrespond to theeigenvectors associated with thelargest eigen- sampleof observationswas considered; at 1-mixintervals estimates of the values.This informationcan be exploitedto reparametrizewith a smaller parameterswere computed. As a functionof bothtime andfrequency, over numberof parameters.The covariancematrix is the integralof the outer a limitedfrequency band, it was shownthat the geneticalgorithms pro- productof the gradientover the parameterspace. Obtaining a goodesti- duced stable estimates for both the environmental and source location mate of this integralwith the Monte Carlo methodusually requires rela- parameters. tively little effort,even for high-dimensionalparameter spaces. Examples are presentedfor geoacousticinverse problems involving acoustic sources 8:50 and receivers located in the ocean. 2aAO4. Adaptation of genetic-algorithm search for matched-field 8:20 inversion of ocean bottom compressional wave speed profiles. ThomasJ. Haywardand T. C. Yang (Naval Res.Lab., Washington,DC 2aAO2. Matched-field inversion of multifrequency data. Peter 20375-5350) Getstort,Dave Hannay,and Don Gingras (SACLANT UnderseaRes. Ctr., 1-19138La Spezia,Italy) Matched-fieldinversion for oceanbottom compressional wave speeds usinga synthetichorizontal aperture has been demonstrated previously in Oeoacousticinversion using single-frequency data measured on a ver- simulationsand data analysesemploying optimization by simulatedan- ticalanay has become a popularmethod for estimatingsub-bottom param- healing[M. Collins,W. Kuperman,and H. Schmidt,J. Acoust.Soc. Am. eters.Inclusion of multiplefrequencies in the inversionsallows exploita- 92, 2770(1992)] and genetic-algorithm search [P. Gerstoft, J. Acoust. Soc. tionof boththe waveguide dispersion and the different penetration into the Am. 95, 770 (1994)].The firstrefereoce noted a lackof sensitivityof the sub-bottomat differentfrequencies. This is achieved,however, at the ex- matched-fieldambiguity function to zero-meanfunctional variations of the penseof greaterrequired computing time, and morecomplicated process- sound-speedprofile. This lack of sensitivitysometimes results in slow ing schemes.Several approaches exist for defininga broadbandobject convergenceof the searchalgorithm when applied to profileswith several function,i.e., coherentor incoherentaddition across frequencies and hy- unknownparameters. This problemis observedin simulationsusing ge- drophones.Each approachhas specificrequirements with regardto the neticalgorithm search. Improved convergence of the geneticalgorithm is recordinggeometry and the sourcespectrum. For coherentaddition across then achievedby usingsome nonstandard procedures, including autolo- frequenciesnot only the sourcespectrum but alsothe absolutepropagation gnusgene exchanges, to generatenew solutions.The simulationsindicate time mustbe estimated.When a usefulobject function has been defined it the practicalfeasibility of inversionfor deep-bottom(up to 500 m) com- is optimlz•dusing genetic algorithms [P. Ocvatoft,J. Acousl.Soc. Am. 95, pressionalwave speedsat a shallow-watersite usinga singlereceiver and 770-782 (1994)] for both the sedimentand the geometricparameters. coherentsynthetic horizomal aperture processing of a towed-sourcesignal. Differentapproaches are illustratedon broadbanddata from the Mediter- raneanNorth Elba site with centerfrequencies of 170 and 330 Hz. The water depthwas 130 m and the sourcerange was 5.5 km. The normal- 9:05 mode code SNA• was used as the forward model. 2aAOS. Optimizing shallow-water sound-speedestimation using parameter resolution bounds. Nicholas C. Makris (Naval Res. Lab., 8:35 Washington-D.C.20375) 2aAO3. Inversion of acousticfield data using genetic algorithms: A techniqueis underdevelopment to optimizeexperimental design for Shallow-waterresults. D. F. Gingrasand P. Gcrstoft (SACLANT estimationof 3-D sound-speedstructure by inversionof acousticdata. The UnderseaRes. Ctr., Vlalc SanBartolomco, 400, 19038La Spezia,Italy) motivationis to takeadvantage of a priori knowledgeof invariantenvi- 3234 J. Acoust.Soc. Am., Vol. 96, No.5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3234 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp ronmentalparameters to estimatethe minimum numberof sensorsneces- described.The underwatersound field radiatedby variousbreaking waves saryand their optimal deployment geometry for a well constrainedinver- intensitiesin freshwater in the rangefrom 0.1 to 20 kHz were reported sion. First, static environmentalinformation, such as bathymetry, earlier[A. R. Kolainiand L. A. Cram,J. Acoust. Soc. Am. (in press);92, geoacousticparameters of the sediment,and mean sound-speed structure 2349(A)(1992)]. These waves were generated by a computed-controlled of the watercolumn, is inputto an appropriaterange-dependent acoustic plunging-typewavemaker and propagatedalong a 12.7-m-longchannel modelfor a givensensor deployment geometry. Next, a theoreticallower wherethey were madeto breakat the midsurfaceof a 3.6-x3.6-x2.4-m boundon estimationerror for the water-columnsound-speed structure is anechoictank. Specificattention is givento a comparisonof the results obtainedvia the Cramer-Raobound. The deploymentgeometry is then obtained in salt and fresh water. The sources of acoustic radiation from perturbeduntil the estimation error is withinacceptable bounds for oceano- bubbleclouds, the averagesound-pressure level, bubbleclouds shape, graphicand acousticmodeling. However, the choiceof sound-speedpa- bubble concentration,and size distribution in these medium are discussed. rametrizationcan alsoseverely affect the accuracyof an inversion.For Theseresults may provideconsiderable insight into the likely source example,an empiricalorthogonal function (EOF) representationtypically mechanisms for ocean ambient noise. hashigher resolution for fewerparameters than a discretecell representa- tion.But thisis at thecost of morelimiting assumptions. These issues are 10:05 addressedby computingthe theoreticallower boundon estimationerror for discretecell, EOF, and Fourierinternal wave representationsof 3-D 2aAO9. Acoustic daylight: Preliminary results from an ambient sound-speedstructure. noiseimaging system. JohnR. Potter,Michael J. Buckingham,Grant B. Deane,Chad L. Epifanio,and NicholasM. Carbone (MPL 0238, 9:20 ScrippsInst. of Oceanogr.,Univ. Calif. at SanDiego, 9500 GilmanDr., La 2aAO6. Coherent acousticbubble sizing in the ocean. B. K. Choi, Jolla, CA 92093-0238) H. R. Lee, and S. W. Yoon (Dept. of Phys.,Sung Kyun Kwan Univ., A broadband(8-80 kHz) multibeam(126) acousticdaylight system Suwon440-746, Republicof Korea) has been developedwhich forms real-time imagesat a 27-Hz frame rate Bubbles are well known to induce variations of acoustic characteristics usingonly naturalambient noise in the ocean.The colorand intensity of in water.The bubblesize distributiongives significantinformation for eachpixel of the final imageis determinedby the spectralshading and understandingunderwater sound propagation and acoustic roles of bubbles intensityof the receivedsignal in eachbeam normalizedto a running- in theocean. Since the conventional acoustic bubble sizing method only averageambient noise spectrum. The firstdeployment of thissystem will consideredsound attenuation due to bubblesaround resonance frequencies be madefrom a floatingresearch platform (ORB) duringAugust in San in a bubblymixture, a bubblesize distribution was incoherently estimated. DiegoBay. The high-frequencyambient noise at thissite is dominatednot In thepresent coherent acoustic bubble sizing method, sound speed as well by surfacewaves, but by coloniesof snappingshrimp (Alpheus and Syn- as sound attenuation are considered to have a coherent estimation of alpheus)associated with nearby structures and other habitats. The prelimi- bubblesize distributionin the bubblymixture. The presentcoherent naryresults from thisdeployment will be presented,including a descrip- methodis provedto describea bubblesize distributionmore accurately tionof thedata processing and color mapping algorithm, the ambient noise thanthe conventional incoherent one. [Work supported by theKorea Sci- environment,and somepreliminary image results from simpletargets at enceand Engineering Foundation.] closerange. [Work supported by ONR.] 10:20-10:35 Break 9:35 2aAO7. Multiple bubbles: Collective modes and the origin of 10:35 superresonances.C. Feuillade (Naval ResearchLaboratory, Stennis SpaceCenter, MS 39529-5004) 2aAO10. Forward-scattering simulations through ocean-ridge hydrothermal.vent diffusive layer turbulence: Feasibility of vent Acousticresonances and scatteringfrom systemsof multipleair monitoring. T. F. Duds (WoodsHole Oceanogr.Inst., Bigelow2, bubblesin water are describedusing a coupleddifferential equation WoodsHole, MA 02543) and D.A. Trivett (DalhousieUniv., Halifax, method.By recombination,the problemmay be analyzedby scattering NS B3H 4J1, Canada) from the individual normal modes of vibration of the ensemble. The modes areof two types:"Symmetric" modes, where the bubbles vibrate in phase Temperatureand velocity fluctuationsin a bottom boundarylayer with each other,typically show downwardshifts in frequencyand in- down-currentof Juande FucaRidge hydrothermal sites were monitoredin creaseddamping; "antisymmetric"modes, where some or all of the 1990 from tripods.The diffuseflow from relativelycool ventsremains bubblesvibrate in antiphase,generally show upward frequency shifts and near the bottom,and acousticrefractive index fluctuationsdecay away reduceddamping and may becomesuper-resonant. For two bubblesthe slowly.Rytov theory-based forward-scattering simulations through struc- methodreproduces frequency shifts measured experimentally. Examina- turesconsistent with the observationsare usedto verify the validityof tion of the modalresponse functions shows that super-resonancesmay Rytovtheory, compare the usefulnessof variouspropagation path lengths occurfor specificbubble spacings if the individualbubbles are primarily andfrequencies on monitoring,and evaluate the ability of acousticphase radiationdamped. For two andthree bubble systems super-resonant scat- and amplituderecordings to monitordesired vent parameters.The Rytov tering is stronglydipolaf and propagateslittle energyin the far field, theoryis valid for someranges and frequencies,but issuessuch as turbu- makingthe phenomenondifficult to observeexperimentally. Scattering lencehomogeneity, energy dissipation rate, boundary-layerdepth, beam from a bubblereflected in a pressurerelease surface should show the patterns,and sensormotion would have strongeffects on the measure- phenomenonstrongly. By extendingmultiple bubbles in a line the damping ments. ratespredicted by Westonfor an infinite line array may be approached.The methodoutlined can easilybe applied,using matrix methods,to describe 10:50 acousticscattering from large ensembles. [Work supported by ONR (Ele- ment602435N). Technical management provided by NRL-SSC.] 2aAOll. Continuouswave and M-sequencetransmissions across the Arctic. PeterN. Mikhalcvsky (Sci. Appl. Intl. Corp.,McLean, VA 9:50 22102), Arthur B. Baggeroer (MIT, Cambridge, MA 02139), AlexanderGavrilov (Andreev Inst. of Acoust., Moscow,Russia), and 2aAO8. Acousticcharacterization of laboratory breaking waves in Mark Slavinsky (Inst. of Appl. Phys.,Nizhny Novgorod, Russia) freshand saltwater. All R. Kolaini (Natl.Ctr. for Phys.Acoust., Univ. In thespring of 1994 a seriesof cw andmaximal length sequences (M of Mississippi,University, MS 38677) sequences)were transmitted2600 km acrossthe Arctic Ocean. The trans- Resultsof a laboratoryexperiment to characterizethe underwater missions were centered at 19.6 Hz from a Russian source located 300 km acousticnoise radiated from breakingwaves in fresh and salt water are northof the SvalbardArchipelago. The transmissionswere receivedin the 3235 J. Acoust. Soc. Am., Vol. 96, No. 5, Pt. 2, November 1994 128th Meeting:Acoustical Society of America 3235 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp LincolnSea (900-kin range) on a 32-elementvertical line array and in the ablychaotic, but the coordinatesand travel times of eigenraysare insen- BeaufortSea (2600-kinrange) on a 32-elementvertical line arrayand a sitiveto initialconditions and ocean fluctuations. The codaof thereception 32-elementhorizontal planar army. Analysisof the transmissionloss, can probablynot be explainedwith a propagationmodel in which the phasestability, array gain, and pulsecompression gain are beingused to sound-speedfield is smoothedto suppressscales smaller than the mesos- developan acousticmonitoring strategy in theArctic for climatestudies. cale. instead,it appearsthat scatteringof soundfrom smallerscales dis- The exceptionalstability of theArctic soundchannel first notedin the carly tributesotherwise axially trappedsound over 1000 m in the vertical,thus 1980s[P. N. Mikhalevsky,J. Aeoust.Sec. Am. 70, 1717 (1981)] make limitingthe verticalresolution achievable with tomography.[Work sup- acousticthermometry potentially a verysensitive indicator of ArcticOcean portedby AdvancedResearch Projects Agency and Office of Naval Re- temperatureand ice changes. search.] 11:05 11:50 2aAO12, Performance limits on acoustic therraometry of ocean 2aAOlS. The Kaneoheacoustic thermometry experiment and waves. climate in the presenceof mesoscalesound-speed variability. leffrcy Fred D. Tappert (Appl. Marine Phys.,RSMAS, Univ. of Miami, 4600 L. Krolik and Sunil Narasimhan (Dept. of Elec. Eng., Duke Univ., Box RickenbackerCswy., Miami, FL,33149) and JohnL. Spiesberger(Penn 90291, Durham, NC 27708) StateUniv., UniversityPark, PA 16802) The ability to measureclimatic changes in oceantemperature is fun- A new parabolicapproximation is derivedand implementedthat effi- damentallylimited by thepresence of mesoscalevariability. Be•.ause ocean ciently gives travel time predictionsthat are accurateto within a few acousticpropagation depends on the range-averagedsound-speed (and millisecondsat a rangeof 1000km andcenter frequency 75 Hz. Sensitivity hencetemperature) profile, long-range acoustic transmissions have been of the full-wavetravel time predictionsto oceanographicand bathymetric proposedas a meansof filteringout mesoscalevariability in orderto inputsalong a 3700-kintrack is studiedby comparisonsto acousticdata measurea global warming related trend in mean temperature.The betweena sourceat Kaneohehaving center frequency 133 Hz anda bottom Cramer-Rat lowerbound (CRLB) on the estimationof a changein the mountedreceiver near the northernCalifornia coast. Path stabilityfor a meandepth-dependent temperature profile is presentedto determinethe time intervalof severalyears is alsoexamined with the new broadbandPE highestaccuracy which could be achievedby acousticthermometry. This model,and full-wave generalizationsof eigenrays,called eigentubes,are workextends [A. B. Beggerocr,I. Acoust. Sec. Am. 95, 2850(A) (1994}] computed.[Work supported by SERDP,ARPA, and ONR.] by evaluatingthe CRLB for differentrepresentations of the mean depth- dependenttemperature profile perturbation with differentlevels of a priori knowledgeabout the mesoscalesound-speed variability. With prior statis- 12:05 tical knowledgeof the mesoscalevariability, the CRLB indicatesthat ac- curatemeasurement of the climatesignal may be possibleusing a general 2aAO16. Change of sound ray by various equations of the sound Chebyshevpolynomial representation of the meandepth-dependent tem- velocity in the 621-1an propagation experiment. Toshio Tsuchiya, peratureperturbation. [Work supported by ONR.] Toshiyuki Nakanishi, Yasutaka Amirant, Hireshi Ochi, Hidetoshi Fujimort (Deep-SeaTechnol. Dept., Japan Marine Sci. and Technol. Ctr., 2-15 Natsushima-cho,Yokosuka 237, Japan), and Akio Hasegawa(Natl. 11:20 DefenseAcad. of Japan,1-10 Hashirimizu,Yokosuka 239, Japan) 2sAt13. High-frequency (>1 cpd} travel time variability of Generally,sound velocity used to be calculatedaccording to equations long-range reciprocal acoustictransmissions in the western North by Wilson(1960), DelGrosso (1974), Cbenand Millere (1977), andothers, Atlant'c. BrianD. Dushaw (A.P.L.,Univ. of Washington,1013 NE 40th whichwere obtainedby directmeasurement in laboratoriesbased on water St., Seattle,WA 98105-6698), Peter F. Worcester,Brace D. Comuelle depth,temperature, and salinitydata collected by the XBT (expendable (Univ. of Caiifomia, La Jolla, CA 92093-0213}, and Brace M. Howe Bathey-tharmograph)or CTD (conductivitytemperature depth) system. (Univ.of Washington,Seattle, WA 98105-6698} However,in observationssuch as ocean acoustic tomography (OAT) where Time seriesof ray travel times were obtainedat 350-, 410-, and it is necessaryto makeaccurate measurement of the soundwave propa- 670-kinranges in thewestern North Atlantic during the 1991-2 Acoustic gationtime overthe distanceof hundredsto thousandsof kilometers,even Mid-OceanDynamics Experiment (AMODE). Transmissionswere re- theslightest difference of thesound velocity can produce significant errors cordedfor approximately300 daysbetween six transceiversin a pentago- in the observatoryaccuracy. Thus the effectof variousequations of the nal array.Sound-speed (current) variability is observedby calculatingthe soundvelocity on the formationof the specificsound ray in the SOFAR sum (difference)of reciprocaltravel times.The sum and differenceof channelwas examinedby usingthe simulationmethod by the soundray reciprocaltravel times are high-passfiltered by removinga daily average. theory.The simulationresults were compared with the specificsound ray The barttropic-tidecurrent is measuredby the differentialtravel times. dataobtained in the 621-kin propagationexperiment in the northeastPa- Both phase-lockedand narrow-bandinternal-tide sound-speed variability, dtic Ocean,and as a result,the equationby Chex and Millere is found to causedby the internal-tide isotachdisplacement, are observedby the sum be the mostconsistent among the threeequations. travel times. The acousticarray acts as a high-directivityantenna for the incidentinternal tide. The observedinternal tide is likely generatedat the 12:20 continentalshelf surroundingthe North American Basin, or perhapsthe Mid-AfianticRidge. The nontidal,high-frequency variability (>1 cpd)is 2aAO17. Long-rangepropagation tests of a 200-Hz soundsource for dueto internal-wavesound-speed and current variability. oceanacoustic tomography. Toshiaki Nakamura, Toshio Tsuchiya, Iwao Nakano,Toshiyuki Nakanishi (lapan Marine Sci. andTechnol. Ctr.. 11:35 2-15 Natsushima-cho,Yokosuka 237, Japan), Ieham Kaihou, Akio Kaya (OkiElectric Industry Co., Ltd., 688 Ozuwa, Nunmzu 410, Japan), 2aAO14. The Kaneohe acousticthermometry experiment and rays. and ToshiakiKikuchi (NationalDefence Academy of Japan,1-10 JohnL. Spiesberger(Dept. of Meteorel.and the Appl. Res. Lab., 512 Hashirimizu,Yokosuka 239, Japan) WalkerBldg., Penn State Univ., UniversityPark, PA 16802) A 200-Hzlow-frequency sound source for oceanacoustic tomography In the 1980s, the Kaneohe source,on the north shore of Oahu, trans- was developedby using a supermagnetostrictivematerial made of the mitredsound (133 Hz; 60-msresolution) from 183-m depth to a U.S. Navy rare-earthmetal (Th, Dy)Fe a aimedat increasing the transmission level and receivera13709-krn distance near northern California. Despite the fact that thereduction of thesound source size. A sound-pressurelevel above 190 soundreflects from the Oahu slopebefore being trapped in the sound dB (re: 1 /xPaat 1 m) witha frequencybandwidth of over50 Hz were channel,ray theory is showncapable of determiningthe spatial coordinates obtainedin the depthrange between 800 and 1200 m. Field testsfor the of the stableacoustic pulses. Rays that bounce from thebottom are prob- long-rangepropagation of severalhundreds of kilometerswere carried out 3236 J. Acoust.Soc. Am., Vol. 96, No.5, Pt. 2, November1994 128thMeeting: Acoustical Society of Amedca 3236 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp nearthe Japan Trench in November1993. The soundsource was moored dentupon the hydrophonearray from the upperand lower direction. The at a depthof 1242m andthe hydrophone array was moored at a depthof signalswere also received by the acousticmonitoring system suspended 1385m. Thedistance between the sound source and the hydrophone array fromthe ship at thedistance of 772 km from thesound source. From these was621 kin. Receiveddata were recorded with a sufficientsignal-to-noise results,it is confirmedthat this sound source has the capability of 1000-kin ratio after achievingbeamforming to discriminatethe soundwaves inci- propagationnecessary for the tomographytransceiver systems. TUESDAY MORNING, 29 NOVEMBER 1994 SAN MARCOS ROOM, 8:30 A.M. TO 12:00 NOON Session 2aNS Noise: Fan Noise and General Topicsin Noise Gerald C. Lauchle, Chair AppliedResearch Laboratory, Pennsylvania State University, P.O. Box30, StateCollege, Pennsylvania 16804 Chair's Introduction4:30 Invited Papers 8:35 2aNSI. Turbofannoise research at NASA. JohnF. Groeneweg(NASA LewisRes. Ctr., M.S. 77-6, 21000 BrookparkRd., Cleveland, OH 44135) Resultsof recentNASA research to reduceaircraft turbofan noise are described. For very high bypass ratio turbofan engines, the dominantsource of enginenoise is thefan. A primarymechanism of tonenoise generation is therotor blade wakes interacting with downstreamstator vanes. Methods of analyzingrotor-stator tone noise generation are described and sample results are given. The analysisincludes the unsteadyaerodynamic response of thestators to gusts,coupling to ductmodes, and finite element calculation of thefar-field radiation accounting of for flow in thefan ducts.Wind tunnel tests of modelfans and nacelles are described including comparisonsbetween measured and predicted tone directivities. A novelrotating microphone technique is usedto measurethe acoustic modesin thefan inlet, and the results indicate that a mechanismassociated with unsteady fan tip loadingcan be important in addition to rotor-statorinteraction. Finally, concepts for activefan noisecontrol which emphasize control at the sourceare addressedby an unsteadyaerodynamic analysis of compliantstator vanes. 9:00 2aNS2.Historical developments in the control of noisegenerated by smallair-moving devices. George C. Maling,Jr. (Empire StateSoftware Syst., Ltd., P.O. Box 2880, Poughkeepsie,NY 12603) The scalinglaws for air-movingdevice noise developed by R. D. Madisonform a usefulstarting point in the developmentof techniquesfor the controlof air-movingdevice noise. The commercialbuilding boom after World War I! providedthe impetusfor researchinto air-moving device noise, and the increase in theuse of homeair-conditioning systems provided the motivation for further research.Beginning in the 1960s,noise generated by computingmachinery became important, and the developmentof air-cooled computingequipment provided a furtherstimulus to noisecontrol research. Developments in the controlof air-movingdevice noise are reviewedwith emphasison scalinglaws, dimensionalanalysis techniques, mechanisms of noisegeneration, noise emission measurements,noise reduction techniques, design guidelines, and system effects. Some suggestions for futureresearch on air-moving devicenoise are given. 9:25 2aNS3.Efficient sound generation in a ductedaxial fan due to a rotatingwavelike flow pattern. M. H. Krane,P. H. Bent,a) andD. A. Quinlan (AT&T Bell Labs.,600 MountainAve., Murray Hill, NJ 07974) Previousinvestigations have shown the presenceof narrow-bandpeaks in the acousticspectra of ductedaxial fansat frequencies otherthan harmonicsof the bladepassage frequency. This phenomenonis of practicalimportance because these peaks are strongest whenthe fan is operatingnear its bestefficiency point. Measurements of the fan flowfieldwere conductedin the rotatingframe using hot-wiresand surface-mountedhot-film sensorsin order to identify the sourceof the narrow-bandtones. These measurementshave showna rotatingwavelike motion composed of severaldiscrete modes. The wave patternwas strongeston the pressureside of the bladein the regionbetween the tip andthe midspan.One of the modesof the rotatingpattern was found to be an integermultiple of thenumber offan blades, resulting inefficient sound generation atthat frequency. a)Present address: Acoustics Technology, McDonnell DouglasAerospace, Mail Code71-35, 1510 HughesWay, Long Beach, CA 90810-1864. 9:50 2aNS4.A modifiedtransfer function method for sourceimpedance in ducts. M.G. Prasadand W. S. Kim (Dept.of Mech.Eng., StevensInst. of Technol.,Castle Point on the Hudson,Hoboken, NJ 07030) Experimentalcharacterization studies of sourceimpedance have resultedin several direct and indirect methods.The transfer function(TF) method,which is a well-knowndirect method, has been quite successful in measuringsource impedance. However, one 3237 d. Acoust. Soc. Am., Vol. 96, No. 5, Pt. 2, November 1994 128th Meeting: Acoustical Society of America 3237 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp importantdrawback of the TF methodis that it fails for the caseof low signal-to-noiseratio in the system.The noisein the system couldbe due either to theoperating source (to becharacterized) or to theflow in thesystem. A novelmethod to overcome the problem dueto low signal-to-noiseratio is presented.A modifiedtransfer function (MTF) is determinedby usingan additionalmeasurement of transferfunction of the systemwith a very low level of signalof the secondarysource used in the method.Then the two transfer functionsare usedto estimatethe MTF. The sourceimpedance is then calculatedusing the reflectioncoefficient which is obtained usingthe MTF. Thisnew MTF methodhas given ve T goodrestfits on a modelelectroacoustic speaker-duct system. A modified coberencyfunction is usedfor erroranalysis. This MTF methodcan be usedto measurethe impedanceof sourcessuch as fansand bloweraused in coolingsystems. 10:15-10:30 Break ContributedPapers 10:30 11:15 2aNSS. Applications of the proposednew method for computing 2aNSS.Legal frame of environmentalnoise in Mtxico. Rafael attenuation of fractional octave bands of a wideband noise by TroyamainLands (Ctr. de Investigacitny de EstudiosAvanzados del atmosphericabsorption. PaulD. Joppa (BoeingCommercial Airplane I.P.N.,Av. Inst. Polittc. Ncl. 2508, San PedroZacateoeo, Mtxico, D.F. Group,P.O. Box 3707,MS 67-ML, Seat0e,WA 98124-2207), LouisC. 07000,Mtxico) Sutherland (RanchoPalos Verdcs, CA 90274), and Allan J. Zuckerwar (NASA LangleyRes. Ctr., Hampton,VA 23681-0001) The regulations,accepted methods of measurement,and standards used A simple methodfor computingthe attenuationdue to atmospheric in Mtxico related to the determination of noise in environmental and labor absorptionfor fractionaloctave bands of noise,outlined in a previous environments,as well as the maximum allowable values in contrastwith paper[P. D. Joppa,L. C. Sutherland,and A. J. Zuckevarar,J. Aconst.Soc. their equivalentsused in the United Statesand Canada,are reviewed. Am. Suppl.1 88, S73 (1990)],is brieflyreviewed and example applica- tionsto aircraftnoise and room acousticspresented. The methoduses an analyticalapproximation of a "representative"frequency for which the pure-toneattenuation loss due to atmosphericabsorption is equalto the 11:30 actualloss for the bandof noise.The resultingtotal band attenuation, 8Lb for propagationover a distances, for a bandwith an exactmidband fre- 2aNS9.Noise regulations in Mexico. FernandoJ. Elizondo (Lab. de quencyf,•, is equalto a nonlinearfunction of the totalpure-tone attenu- Acfist.,Facultad de IngeniedaMce•nica y Eltctrica,Univ. Auttnoma de ationa(f,,).s over this pathwhere a(f•,) is the pure-toneattenuation NuevoLetn, P.O.Box 28 sucursalF, Cd.Universitaria, San Nicolfis, N.L, coefficientat theexact midband frequency f,•. Themethod provides better 66450, Mtxico) estimates than in SAE ARP 866A for the true band attenuation when the •otaltrue band attenuation is lessthan about 50 dB. For applicationto room acoustics,it is shownthat the "distance"s involvedis simplyequal to the An overview of the regulationson noisein Mexico is presented.In- reverberationtime, T timesthe speedof soundin the room. cludedare historicdevelopment, classification, categorization, contents, andsources. Information on how to updateand obtain the lawsand regu- lations is also mentioned. 10:4S 2aNS6. Noise assessmentand prediction system (•es) evaluation. 11:45 John M. Noble, Robert O. Olsen (U.S. Army Res. Lab., Battlefield 2aNSI0. Noise levels in Mexican industry. JumlAntonio Ortiz Garcia Environment Directorate, AWl?N: AMSRI-BE-S, White Sands Missile, Range,NM 88002),and RichardOkrasinski (New MexicoState Univ., (lngenieriaAcfst. Spectmm,S. A. de C. V. Apaseoel Allto No. 21-2, Las Cruces,NM 88001) ColoutsSan BarroloAtepehuac•n, Delegacitn Gustavo A. Madero, Mtxico 07730 D.F., Mexico) A systemhas been designedto provide an assessmentof noise levels that resultfrom testingactivities at AberdeenProving Ground, MD. The Since1985, labor regulations on noiseexposure have existed, and as in systemreceives meteorological data from surfacestations and an upperair soundingsystem. The meteorologicaldata are usedas inputinto an acous- othercountries, the quantityemployed is theA-weighted sound-pressure tic my trace model which projectssound level contoursonto a two- level. Maximum allowableexposure levels were takenfrom ISO-1999- dimensionaldisplay of thesurrounding area. This information is alsopro- 1975.According to local statisticsof professionalillness, hearing loss videdto therange control office where a decisioncan be madeto proceed occupiessecond place in importance.The measurementrestfits of or delaythe testactivity depending upon acoustic propagation conditions. A-weightedsound-pressure levels in differenttypes of Mexicanindustries, To evaluatethe noiselevel predictions, a series of microphonesis located from 1990 to 1993, are described.These measurementswere made in off the reservationto monitorsound-pressure levels. 9my eventsof signifi- concordancewith officialmethodology. The resultsshowed that less than cant level are transmittedback to the central displayunit, allowing for 50% of a sampledpopulation stayed in a noisyambient (continuous or comparisonbetween prediction and data.The computermodels are modu- fluctuating)with levels higher than 90 dBA. It is consideredthat A lax,allowing for a varietyof modelsto be utilizedand testedto achievethe weightedsound-pressure level is not enoughto properlydescribe noise at best agreementwith data. This techniqueof predictionand model valida- tion will be usedto improvethe noiseassessment system. the workplace;due to high level valuesusually encountered at low fre- qoeucies,which, even though they axenot normallyaudible, may cause workers'low performance,beside other biological and psychological ef- 11:00 fects.Frequency analysis results of the sameindustries and how they are employedfor thecalculation of otherquantities, like loudnessand noisi- ness, are also described. 2aNS7. Abstract withdrawn. 3238 J. Acoust. Soc. Am., Vol. 96, No. 5, Pt. 2, November 1994 128thMeeting: Acoustical Society of America 3238 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp TUESDAY MORNING, 29 NOVEMBER 1994 WEDGWOOD ROOM, 8:25 TO 11:40 A.M. Session 2aPA PhysicalAcoustics: Sonoluminescence and SonochemistryI RonaldA. Roy, Chair AppliedPhysics Laboratory, University of Washington,Seattle, Washington 98105 Chair's Introductions8:25 Invited Papers 8:30 2aPAI. Sonoluminescence.Lawrence A. Crumand Scan Cordry (Appl.Phys. Lab., Univ. of Washington,Seattle, WA 98105) In 1896,Henri Becquerel discovered that a uraniumsalt could darken a photographicplate, and from this effect went on to discover radioactivity.In 1934, Frenzeland Schultesdiscovered that acousticwaves, generated in a water bath, could also darkena photo- graphicplate. They attributedthis effect to luminescencefrom the soundfield, a phenomenonthat would later be knownas sonolu- minescence.A soundfield by itself doesnot causelumineseence; it is throughthe mechanismof acousticcavitation, whereby microscopicgas bubbles are causedto oscillateso violentlythat a remarkableenergy concentration occurs. Under certain conditions, thecavitation event is transitory,and self-destructs within a few acousticcycles; under other conditions, a stablebubble will luminesce for extendedperiods of time.This initial presentationwill serveas a generalreview of the phenomenonof acousticeavitation and demonstratehow bubbledynamics leads to manyof the observedeffects. Later papersin this sessionwill providemore detailof variousaspects of thegeneral phenomenon. [Work supported in partby theOffice of NavalResearch.] 8:55 2aPA2. Probingthe unknownsof sonoluminescence.Bradley P. Barber,Robert Hiller, Ritva L6fstedt,Keith Weninger,and Seth Putterman(Phys. Dept., UCLA, LosAngeles, CA 90024) The mechanismwhereby a bubbletransduces sound into a clocklikestream of picasecondflashes of ultravioletlight is robust, complex,and unknown. A theoreticalunderstanding of the key bubbleparameter, its ambientradius, is lacking.An explanationas to why this phenomenonhas so far only beenseen in water is elusive.In addition,we do not understandwhy coolingthe waler dramaticallyincreases the light outputor why sonoluminescenceis so sensitiveto dopingwith a noblegas. Experimentally, the spectrumhas been unable to be followedpast 7 electronvolts and so the limitsof energyconcentration which can be achievedwith sonolumineseencefrom a singlebubble are not yet measured.In additionto yieldingclues experiments in progresswill mostlikely serveto deepenthe mystery! [Work supported by theUS DOE Divisionof AdvancedEnergy Projects; RL is anAT&T Fellow.] 9:20 2aPA3. Experimental determinationsof transient conditionsduring cavitation. KennethS. Suslickand KalhleenA. Kemper (Dept.of Chemistry,Univ. of Illinois,505 S. MathewsAve., Urbana,IL 61801) The collapseof cavitationbubbles generates intense local energy release, resulting in extremelocal heating, high local pressures, andhigh energy chemistry. Determining the localconditions formed during cavitation, however, has proved to be a difficultproblem. In ourwork, SOhochemical reactions and the sonoluminescence that results have been used as quantitative probes of bothtemperature andpressure during cavitation. The effectivetemperatures reached during cavitation can be probed by measurementof therelative rates of a seriesof chemicalreactions whose temperature dependence is alreadyknown. Comparalive rate tbermomelry of multibubble cavitatibn(immersion horn at 20 kHzand •30 W/cm2) yields effective temperatures of •5200 K in hydrocarbons[K. S. Suslick, Science247, 1439 (1990)].Consistent with this,sonoluminescence in these liquids closely resembles flame emission from excited statesof Ca; rotationaland vibrational fine structure permits a spectroscopicdetermination of theemission temperature of C2excited statesat 5080+160K [E. B. Flintand K. S. Suslick,Science 253, 1397(1991)]. Sonoluminescence from excited state metal atoms is producedfrom sonolysis of organomelalliccompounds, for whichthe linewidth determines Ihe collisional lifetimes of emittingatoms andthe effective local pressures. For excited state Cr atomsproduced from Cr(CO) 6, emissionlifetime is only0.20 ps,corresponding tolocal densities of --0.15 g/cm 3 or pressuresof '--1.5 kBar at 5000K. [SupportedbyNSE] 9:45 2aPA4.Picosecond sonoluminescence from macroscopicto microscopicmodels. T. Lepoint,F. Mullie, Y. Lambillotte (Lab.de Sonochimieet d'Etudede la Cavitation,Inst. Meurice, 1, Av. E. Gryzon,1070 Brussels,Belgium), M. Goldman,A. Goldman, and P. Tardiveau (EcoleSup6ricure d'Electricit6, 1192 Gif-sur-YvetteCedex, France) The discoveryof stable"picosecond" sonoluminescence (SL) hasstimulated a greatdeal of theoreticaleffort aimed at explaining thisstriking result. Instead of assuminga perfectlysmooth spherical bubble (as in the hot-spottheory, the convergingshock-wave modelor the Castmireffect model), our modelis basedon bubbledeformation and the subsequentdisruption of the interfacetoward 3239 d. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November 1994 128th Meeting:Acoustical Society of America 3239 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp theend of thecollapse. The formationof an intracavityspray via theTaylor (hydrodynamic) or theRayleigh (electrohydrodynamic) instabilitiesand the electrificationof the tiny dropletsdue to the disturbancesof the interfacialelectrical double layer duringthe sprayingprocess are described. The high electrical field (E--109 Vm t) characterizinga small area of a dropletsurface isconsidered to be responsiblefor the field emissionprocess. The formationand expansionof a densemicroplasma inside the cavity as a consequenceof the emission of electronsis proposedto be theorigin of picosecondsonoluminescence. By means of thismodel, which is basedboth on hydrodynamicsand on the microstructureof the bubble interface, the mainexperimental observations (SL flash temporallocalization and duration, shape of theSL spectrum)can be explained. 10:10-10:25 Break 10:25 2aPAS.Spherical shocks in a van der Waalsgas and their stability C.C. Wu (Dept.of Phys.,Univ. of California,Los Angeles, CA 90024)and P.H. Roberts (Univ.of California,Los Angeles, CA 90024) A theoryof sonoluminescencehasbeen developed based on the compression andeventual ionization of air in a bubblel•y the convergingshock waves generated by the appliedacoustic radiation. The air is compressedto suchhigh densities that departures from the idealgas law becomevery significant.An extensionto the van der Waalsgas has been made to the similaritytheory of Guderley for the structureof sphericalshocks in an ideal gas.The linearstability of theseshocks has also been examined. 10:50 2aPa6. Hydrodynamicsimulations of bubble collapseand picosecondsonoluminescence. William C. Moss (Lawrence LivermoreNatl. Lab., L-200, P.O. Box 808, Livermore,CA 94550), DouglasB. Clarke,John W. White, andDavid A. Young (LawrenceLivermore Natl. Lab., Livermore,CA 94550) Numericalhydrodynamic simulations of thegrowth and collapse of a 10-/zmair bubblein waterwere performed. Both the air and thewater are treated as compressible fluids. The calculationsshow that the collapse is nearlyisentropic until the final 10 ns,after which a strongspherically converging shock wave evolves and creates enormous temperatures and pressures in the inner0.02 p.mof the bubble.The reflectionof the shockfrom the centerof the bubbleproduces a divergingshock wave thatquenches the high temperatures (>30 eV) and pressuresin lessthan 10 ps (FWHM). The picosecondpulse widths are due primarilyto sphericalconvergence/ divergenceand nonlinear stiffening of the air equationof statethat occurs at high pressures.The peaktemperature at thecenter of the bubbleis affectedstrongly by the ionizationmodel usedfor the air. The resultsare consistentwith recentmeasurements of sonolu- minesccncethat had optical pulse widths less than 50 ps and30-row peakradiated power in the visible.[This work was performed underthe auspicesof the U.S. Departmentof Energyby LawrenceLivermore National Laboratory under Contract No. W-7405-Eng- 48.] 11:15 2aPA7.Is sonoluminescencecoliision-induced emission? Lotbar Frommhold (Phys. Dept., Univ. of Texasat Austin,Austin, TX 78712-1081)and AnthonyA. ArchIcy (NavalPostgraduate School, Monterey, CA 93943) An estimateis attemptedof thecollision-induced emission (CIE) intensityand spectral profile in thevisible and near UV region of thespectrum of N2-X pairs,where g representsanother N 2 moleculeor an argonatom, etc., for conditionsthat correspond to shock wavesbelieved to existin sonoluminescanceexperiments. Calculated profiles consist of superimposedhigh overtonebands and resemblemeasured profiles of sonoluminescencespectra. The intensitiescalculated on the basisof a few, simpleassumptions concerningthe induced dipole surface compare favorably with measurements.The agreementobtained suggests that collision-induced emissionis a viableor evenan attractive alternative to bremsstrahlung to explain sonoluminescence. According to thetheory presented, the CIE sourceis optically thin so that the spectralemission profile is not related to Planck'sradiation law. 3240 d. Acoust.Soc. Am., VoL 96, No. 5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3240 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp TUESDAYMORNING, 29 NOVEMBER1994 PECOSROOM, 8:15 A.M. TO 12:00NOON Session 2uSA StructuralAcoustics and Vibration:Scattering from ElasticStructures Linda P. Franzoni, Cochair Departmentof MechanicalEngineering and Aerospace Engineering, North Carolina State University, Raleigh, North Carolina 27695-7910 Geoffrey L. Main, Cochair Officeof Naval Research,800 North QuincyStreet, Arlington, Virginia 22217 ContributedPapers 8:15 consistsof a fixedsource, a fixedreceiver, and a targetplaced in between. The locationof the targetis varied,to comparethe incidentfield to the 2aSA1. Energy flux vector field in an ensonifiedelastodynamic scatteredfield in bothintensity and arrival times. sphere. Cleon E. Dean (Dept. of Phys.,Georgia Southern Univ., LandramBox 8031, Statesboro,GA 30460) and Michael E Werby (NRL, StennisSpace Center, MS 39529-5004) 9:00 Recentinterest has been shownin the energyflux densityinside an 2uSA4. Acousticscattering from a fluid-loadedelastic plate with a ensonifiedelastodynamic scatterer. A sphericalmodel was chosenas the distributedmass inhomogeneity. J.M. Cuschieri (Ctr. for Acoust.and simplestand most generalgeometry to analyze.To properlymodel the Vib., Dept. of OceanEng., FloridaAtlantic Univ., BocaRaton, FL 33431) energyflow in an elastodynamicmedium, it is necessaryto employthe and D. Felt (David TaylorResearch Center, Bethesda, MD 20084) elastodynamicequivalent of the Poyntingvector. Plots of the vectorfield of the elastodynamicintensity are presentedwith an eye towardthe clas- The scatteringof a planeacoustic wave by a fluid-loaded,thin, elastic siftcationof the type of resonancebehavior displayed. Analogies with plate,of infiniteextent, with a distributedinhomogeneity is investigatedby otherresonance phenomena in relatedgeometries suggest the possibility of solving the equationof motion in the wave-numberdomain using the fruitfulcomparison with resonancemodes in shellsand plates. [Work in hybridnumerical analytical approach [J. Acoust. Soc. Am. 95, 1998-2005 thisarea supported by ONR/NRL andby ASEE/ONT SummerFellowship (1994)].The presence of thedistributed inhomogeneity in the equation of Program.] motion,when expressed in thewave-number domain, results in a Fredholm integralequation of the third kind. By substitutingfor the productof the 8:30 responseand the plate characteristicequation, the Fredholmintegral of the third kind is reducedto a Fredholmintegral of the secondkind. The plate 2aSA2. On the scattering crosssection of bodies in inhomogeneous responsein the wave-numberdomain is obtainedfrom the solutionof the medium. YucpingGuo (Dept.of OceanEngineering, MIT, Cambridge, Fredholmintegral. Inverse Fourier transforming the wave-numberdomain MA 02139) responsefunction gives the spatialdomain solution for the response.The hybridapproach is usedto performthe inverseFourier transform. The A theoremis proventhat relatesthe scatteringcross section of arbi- scatteredpressure is obtainedin a similarmannen Response and scattered trarily shapedscatterers to the scatteredfar field in one or two particular pressureresults for distributedmass inhomogeneities, with differentdis- directions.This canbe regardedas a generalizationof the classicaloptical tributionfunctions, are presentedand comparedto the resultsfor a line theorem(also known as the extinction theorem) for homogeneousmedium inhomogeneity.[Work sponsored by ONR.] of infiniteextent. In that case,the scatteringcross section is given by the far field in the forwardscattering direction. For a half-spacewith a bound- ing surfaceof arbitrarymechanical properties, it is shownthat the scatter- 9:15 ing crosssection is givenby the scatteredfar field in the specularreflection direction.For an inhomogeneousmedium with abruptdensity and sound- 2aSA5. Influence of rib resonanceson the acoustic scattering from speedchange at an interface,the scatteringcross section is givenby the far rib reinforced elastic plates. Angela K. Karali and Sabih I. Hayek field in boththe specularreflection direction and the transmissiondirection (Dept. of Eng. Sci. and Mech., Penn State Univ., UniversityPark, PA thatobeys the Snell's law. [Work supported by ONR.] 16802) In a previouspaper [A. K. Karaliand S. I. Hayek,J. Acoust. Soc. Am. 8:45 95, 2805 (1994)] the analyticmodel for the predictionof the acoustic scatteredfield by infiniteelastic plates reinforced with periodicarrays of 2uSA3. Forward scattering from hemispherically end-capped line discontinuitieswas presented. In thispaper the analysisis extendedto cylindricalshell in shallowwater. AngieSarkissian (Naval Res. Lab., infiniteelastic plates reinforced with periodicarrays of ribs.If actualribs Washington,DC 20375-5350) are attachedto a plate,instead of line discontinuities,their impedances are Whenmeasuring the scatteredfield from a targetin the exactforward frequencydependent. The ribsare modeled as Timoshenko beams attached direction,the presenceof a significantlystronger indicident field makesthe to an elasticplate, whose flexural vibrations are modeledusing Mindlin's extractionof the scatteredfield difficult becausethe two signalsarrive platetheory. Analytic expressions for the rib impedancesare obtainedand almostsimultaneously. As the positionof the targetchanges, the two sig- plottedagainst the normalizedfrequency of an incomingplane acoustic nals arrlvo at distinot times to mak• the scattered field •aai•r to •xtraot. In wave. The rib impedancesshow resonancesand antiresonancesin the a boundedmedium, multipath arrivals produce additional complications by frequencyrange of 1 to 15 timesthe classicalcoincidence frequency of the increasingthe durationof the incidentfield. Frequencyand time domain plate.The influenceof the rib impedanceresonances and antiresonances on computationsare made for thescattered field from a hemisphericallyend- the nonspecularlyreflected field is demonstratedby directcalculation of cappedcylindrical shell placed in a boundedmedium where the geometry the acousticscattered field at severalcritical frequencies of the ribs. 3241 J. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128th Meeting:Acoustical Society of America 3241 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 9:30 as predictedby SARA 2D finite-elementmethods. [Work supported by O•R.] 2aSA6. Analytical numerical matching for efficient calculation of acoustic scattering from cylindrical shells. Richard C. Loftman and DonaldB. Bliss (Mech. Eng. and Mater. Sci., Duke Univ., Box 90300, 10:30 Durham, NC 27708) 2aSA9. Experimentalinvestigation of backscatterfrom an internally Structuraldiscontinuities in highly coupledfluid/structure systems are loadedcylindrical shell with a constrainedlayer damping treatment. modeled by a novel approachcalled analytical numericalmatching Michael Klausbruckner,Matthew Confi, Ira Dyer, and J. RobertFricke (ANM). ANM separatesthe low-resolutionglobal influence of a disconti- (Dept.of OceanEng., MIT, Cambridge,MA 02139) nuity from the relatively high-resolutionlocal effects.A continuous, smoothedreplacement for a fundamentalstructural discontinuity is con- Previousinvestigations have examined the backscatter from empty and strutted so that the systemis identicallyunchanged beyond a small internallyloaded shells with no dampingtreatment, demonstrating the smoothingregion. Simultaneously, the preciselocal effect of smoothing primaryimportance of helicalshear waves. The helicalwaves contribute to the discontinuityis retainedin analyticalform. The smoothedproblem is largebackscatter for aspectangles within 30 degof normalfor theempty solvedby numericaltechniques, with rapidconvergence and reduced com- shell.The regionincreases to 45 degof normalfor the internallyloaded putationalcost. The original discontinuous character is restored,using the shells.A constrainedlayer was appliedto the cylindricalsection of an analyticalexpression for the localdifference between the smoothed and the internallyloaded shell to dampthe helicalwaves while recoupling them originalproblems. ANM hasbeen successfully applied to acousticscatter- from the internal structures. The intended effect was to lower the back- ing from a thin, infinitelylong cylindricalshell, with multiplestructural scatterlevels and reduce the angularwidth of strongbackscatter to within discontinuities.Local solutions for line discontinuitieswith radial,tangen- 30 degof normal.This preliminary investigation demonstrates the achieve- tial, and rotationalconstraints have been formulatedusing ANM. Line mentof eachof thesegoals. In addition,the importanceof directacoustic constrainedscattering problems, as well as line drivenproblems, are in- backscatterfrom the attachmentlocations of the internalrings was high- vestigated.The abilityof analyticnumerical matching to replacea discon- lighted.The bistatic measurements were conducted over a frequencyrange tinuousphysical problem by a well-behavedcontinuous one for numerical of 2.5 9:45 10:45 2aSA7. Approximateclosed.form analysis of modal couplingfor 2aSA10.Point-matching technique for scatteringof StokesJanflows radiation and scattering from fluid loaded structures. Linda P. aroundaxisymmetric bodies. ScottA. Wymer,Rcnata S. Engel,and Franzoni (Mech. and AerospaceEng., North Carolina State Univ., AkhleshLakhtakia (Dept. Eng. Sci. and Mech., The Pennsylvania State Raleigh,NC) and DonaldB. Bliss (DukeUniv., Durham, NC 27708) Univ.,227 HammondBldg., University Park, PA 16802-1401) Modalanalysis is oftenused in problemsinvolving radiation and scat- In solvingfor velocityand pressurefields in a slow,viscous, incom- tering from fluid loaded structures.The modal formulationleads to a pressiblefluid, frequency-domain scattering techniques can be brought into coupledsystem of equationsfor themodal amplitudes. Typically, structural actionby takingthe Fourier transform of theequations describing Stoke- modesare coupledthrough the effectsof the fluid. In practice,modal sianflows. This is exemplifiedby consideringthe scattering of a transverse couplingis sometimesassumed unimportant, enabling modal coefficients planewave by an impenetrableaxisymmetric body immersed in a fluid to be solvedindependently in closed form. This approach is particularly modeledby theunsteady Stoke's equation, the wave number in theambi- appealingwhen subsequent analytical treatment of expressionsis desir- ent Stoke'sfluid being necessarily complex. The pressureand velocity able. The validity of this approach,including the orderof the error in- phasorssatisfy the Laplace and the Helmholtz equations, respectively, and volvedin neglectingcoupling is discussed.It is shownthat the principal arewritten as sums of incidentand scattered components. These compo- effectsof weak modalcoupling can be incorporatedin a simpleway nentsare then expandedin termsof sphericalharmonic functions. The without solvingthe fully coupledsystem. An approximateclosed-form point-matchingtechnique is usedto satisfyboundary conditions on a dis- solutionfor weaklycoupled systems of equationsis developed.The ap- creteset of pointson the surface of thescattering body. Convergence of the proximationis foundto workwell, evenin systemswhere coupling is resultingseries solutions is studiedfor spheroidsof differentaspect ratios fairly strong.The approximateform givesphysical insight into the domi- andfor varyingwave numbers. nanteffects of modalcoupling, and shows that neglecting coupling may leadto significanterrors. The effectsof couplingare assessed by solution of modelproblem involving acoustic scattering from a fluidloaded plate. 11:00 Solutionsare compared for threemethods: fully coupled, uncoupled, and theapproximate analysis. [Work supported by ONR.] 2aSAll. Acousticswave diffraction on a cylindricalshell with two localmasses. Rostislav A. Dudnikand Andrei B. Kolpakov(Dept. of Phys.,Inst. Arch. & Civil Eng.,65 II'inskayaSt., 603600 N.-Novgorod, Russia) 10:00-10:15 Break Thediffraction of a planesound wave on a thincylindrical shell having inhomogeneitypresented by two identicalinertia masses fastened sym- 10:15 metrically on its surfaceis considered.It is shownthat the field scattered 2aSAS. Reciprocityrelations for endcapscattering of natural waves by •ucha shellprc•cnts a •upcrpos|tionof thefields radiated by boththe on a fluid-loadedcylindrical shell. P. W. Smith,Jr., Kevin D. LePage, symmetricaland antisymmetricallow-frequency azimuth modes excited andJ. GregoryMcDaniel (Bolt Beranekand Newman,Inc., 70 Fawcett dependingon thedirection of initialwave propagation toward the vertical St., Cambridge,MA 02138) planeof theshell symmetry (q•=0; if)= 180). In supportof theexistence of correspondingnonsingular normal velocity distributions, a specialized ex- The responsefield on a finiteaxisymmetric elastic shell is approxi- perimentalinvestigation was carriedout for the force-excitedshell models. matedby a limitedset of lightlydamped natural waves which are coupled The experimentalinvestigation of near as well as far acousticalfields of to eachother and to far-fieldsound by thescattering process at theend- theseshell was executed also. The calculationresults of frequencyre- caps.In this talk the constraintsupon the scatteringfunctions that are a sponsesand directionality diagrams of thefield scattered by theshell with consequenceof the principle of reciprocityare obtained through analysis. twomasses fastened diametrically opposed at theinitial only symmetrical Resultsshow that the reciprocityconstraints predicted for a thin shell oscillationsare presented. These results am compared with analogous re- exampleagree well with the observed behavior of naturalwave scattering sultsfor the shellhaving one inertia mass (at 4,=180). It wasfound that 3242 d.Acoust. Soc. Am., Vol. 96, No. 5, Pt. 2, November 1994 128thMeeting: Acoustical Society ofAmerica 3242 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp the radiationlevel control is possiblefor the investigatedoscillation struc- otherpoints. A modalanalysis, however, shows that the actual ratio should tureby suchdivision of a unit inhomogeneityin certainfrequency ranges. be three.A moredetailed theory shows that the enhanced return factor is 2 at moderatetimes, but 3 at late timescomparable to the modaldensity. The 11:15 theoryindicates that the factorof 2 is achievedonly if the eigenfxequenc5, statisticshave the spectralrigidity predictedby randommatrix theory. 2aSA12. Scattering of sound by a free-flooded cylindrical shell. K. Thusa connectionbetween spectral rigidity and weak localization is hinted Steven Kim (SignaturesDirectorate, Carderock Div., Naval Surface at. Numericalsolutions in modelundamped two-dimensional reverberation WarfareCtr., Bethesda,MD 20084-5000) roomsare found to agreewith the theory.The effectof dampingon these resultsis alsoinvestigated. Scatteredacoustic pressure fields are obtainedwhen a free-flooded cylindricalshell of finite lengthis subjectedto planewaves incident ob- liquelyto theaxis of thecylindrical shell. Integral equations are formulated 11:45 for the casesof a rigid thin shell and a elasticthin shell with simply supportedboundary condition at both ends.Equations are solvedby a 2aSA14. Scholte interface wave on a cylindrical shell. G. Maze, E Rayleigh-Ritztype approach. Near-field and far-field acoustic pressures of L6on,F. Lecroq,D. D6cultot (LAUE, URA 1373of theCNRS, Univ. of the scatteredsound are calculated. Scattered far-field acoustic pressures for LeHavre, 76610 Le Havre, France), and H. '0befall(Univ. of LeHavre, a shortshell and a long shell are discussed. Franceand Catholic Univ., Washington, DC 20064) The fluid-borneinterface wave on an evacuatedcylindrical shell im- 11:30 mersedin water is knownas Scholte-Stoneleywave, or also asA wave [Talmantet al., J. Acoust.Soc. Am. 86, 278 (1989)].The resonancesof 2aSA13. Enhanced backscatter in finite reverberant systems. thiswave, caused by phasematching upon its multiplecircumnavigations RichardL. Weaver (Dept. of Theor.and Appl. Mech., Univ. of Illinois, of the scatteringobject, can be observedin the backscatteringspectra of 104 SouthWright St., Urbana,IL 61801) incidentsound waves within a frequencywindow that depends on the shell Enhancedbackscatter, in whichreverberant signal levels at theposition thickness,for thicknessesless than 40% of the cylinderradius. The inter- of a transientsource are greaterthan meanreverberant signal levels else- actionbetween the flexuralwave A 0 in the shell, and the Scholtewave is where,is studiedanalytically and numerically.Popular weak localization studiedin detail as a functionof shell thickness.Dispersion curves for the arguments,in whichdescriptions of responsesin termsof incoherentrays A andthe A 0 wavesare presented, indicating a regionof repulsionbetween are modified to include some effects of coherent interference, indicate that thesetwo curvescorresponding to a changeof the physicalnature of the the mean-squareresponse at the sourceshould be twice as largeas it is at two waves. TUESDAY MORNING, 29 NOVEMBER 1994 BALLROOM A, 8:30 TO 11:45 A.M. Session 2aSP SpeechCommunication and EngineeringAcoustics: Microphone Arrays: Designand ApplicationsI JamesL. Flanagan,Cochair CAIP Center,Busch Campus, Rutgers University, Core Building 706, Piscataway,New Jersey08855-1390 HarveyF. Silverman,Cochair Laboratoryfor EngineeringMan/Machine Systems, School of Engineering,Brown University, Providence, Rhode Island 02912 QiguangLin, Cochair CAIP Center,Rutgers University, Core Building, Frelinghuysen Road, Piscataway, New Jersey 08855-1390 Chair's lntroduction-•8:30 Invited Papers 8:35 2aSP1.Microphone systems and signal processing: New opportunities in sound capture. I. L. Flanagan(CAIP Ctr., Rutgers Univ.,Piscataway, NJ 08855-1390)and H.F. Silverman(Brown Univ., Providence, RI 02912) Overthe recent past, advances in twotechnical areas have opened new opportunities for sophisticatedsound capture at distances. High-qualitylow-cost acoustic sensors, primarily in theform of electtelmicrophones, areplentiful and can be used in largenumbers. Continuedprogress in microelectronics nowprovides enormous amounts of economicalcomputation. These incentives have stimulated researchin newtechniques for soundcapture in practicalacoustic environments-•such asconference halls, noisy computer rooms, teleconfercncingfac,illti•a, and mobile communication. Rec•nt rasearch has embraced the design of largegeale tx.•o- and throe dimensionalarrays of microphones,andthe implementation of algorithms for automatic sound source location. This report reviews the statusof researchin these areas. It alsohighlights the emerging applications of distant-talking sound capture for hands-free operation of communicationsequipment such as automatic speech recognizers. [This research issupported bythe National Science Foundation underContract #MIP 9314625.] 3243 J. Acoust.Soc. Am., Vol. 96, No.5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3243 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 8:55 2aSP2. Practical issuesin the use of a frequency-domaindelay estimatorfor microphone-arrayapplications. JohnAdcock, Joe DiBiase,Michael Brandstein (Box D, BrownUniv., Providence,RI 02912), and HarveyE Silverman (BrownUniversity, Providence,RI 02912) A frequency-domaindelay estimator has been used as the basis of a microphone-arraytalker location and beamforming system [M. S. Brandsteinand H. E Silverman,Techn. Rep. LEMS-116 (1993)]. While the estimatorhas advantages over previously employed correlation-baseddelay estimation methods [H. F. Silvermanand S. E. Kinman,Cornput. Speech Lang. 6, 129-152 (1990)],including a shorteranalysis window and greateraccuracy at lower computationalcost, it has the disadvantagethat sincedelays between microphonepairs are estimated independently of one another., there is nothingto ensurethat a setof estimateddelays corresponds to a singlelocation. This not only introduces errors in talkerlocation but degrades the performance of thebeamformer. A methodfor delay estimationand talker location with a microphonearray is describedthat preserves the low computationalcomplexity and rapid tracking ability of the frequency-domaindelay estimator,while improvingthe coherenceand stabilityof the estimateddelays and derived sourcelocations. Experimental results using data from a real 16-elementarray are presentedto demonstratethe performanceof the algorithms.[Early work principally funded by DARPAINSFGrant IRI-8901882, and current work by NSFGrant No. 9314625.] 9:15 2aSP3. A constant-directivitybeamforming microphone array. Gary W. Elko, Thomas C. Chou, Robert J. Lustberg,and MichaelM. Goodwin (Aeoust.Res. Dept., AT&T Bell Labs.,600 MountainAve., MurrayHill, NJ 07974) The qualityof audioteleconferencing in largerooms and noisy environments can be increasedwith the useof steerabledirectional microphonearrays. A minimumbandwidth of 4 oct is requiredto faithfullytransmit the speechsignal. In a typicalteleconferencing arrangement,only discrete angular directions are of interestand therefore the microphone steering directions are quantized. A standard delay-sumbeamformer can result in noticeablefrequency response changes as the talkermoves between these steering localions. In an effort to mitigatethis problem,a broadbandconstant-direc•ivity beamformer has beendesigned and constructed.A few of the algorithmsdeveloped in thiswork will be discussedand compared to existingtechniques. Basically, the solutionrevolves around the designof FIR filtersthat are insertedin the delay-sumbeamformer after each element. A constant-bcamwidth4 oct steerablelinear arraymicrophone using directional elements will be described.A real-timeimplementation utilizing multiple AT&T DSP3210digital signalprocessors is alsodescribed. 9:35 2aSP4. Hands-free mobile telephony by means of an adaptive microphone array. Sven Nordholm, Ingvar Claesson,Sven Nordebo,and Mattias Dahl (Dept.of SignalProcess., Univ. of Karlskrona/RonnebyS-372 25 Ronneby,Sweden) By employingspeech generation models and new algorithmsmore and morea priori informationabout speech signals is utilized in speechrecognition and speechcoding. A fair signal-to-noiseratio is thereforerequired to ensurethat the a priori informationis correct.This impliesa needfor noisereduction under adverse conditions, such as hands-freeoperation of telephonesin the car compartmentor speech recognition in cars IS. Nordholmet al., "AdaptiveArray Noise Suppression of Handsfree Speaker lnput in Cars,"IEEE Trans.Veh. Tech. 42, 514-518 (1993)].The paperpresents two adaptivemicrophone array schemes, aimed for this situation.The first,denoted spatial filtering generalized sidelobe cancellet (SFGSC), gives good noise suppression with little distortion of the speechbut requirescareful calibration. The second,denoted adaptive microphone array employing calibration signals recorded on-site(AMAEC), facilitates a simple buih-in calibration. It is beneficial from a userpoint of viewto usea calibrationsignal recorded on site eliminatingamplifier tuning and microphoneselection. The calibrationcan be donewithin 60 s. The AMAEC calibratesthe arrayto thespeakers' location, microphone positions and lobe gains, amplifiers, and to theacoustic environment in thecar. No a priori informationabout signal statistics or arraygeometry is utilized.[Work supported by Nutek.] 9:55-10:10 Break 10:10 2aSPS.Robust hands-free speech recognition. QiguangLin, Chi Wei Che, andJames Flanagan (CAIP Ctr., RutgersUniv., Piscataway,NJ 08855-1390) Whenspeech recognition technology moves from the laboratory to real-worldapplications, there is increasingneed for robustness. This paperdescribes a systemof microphonearrays and neural networks (MANN) for robusthands-free speech recognition. MANN hasthe advantagethat existingspeech recognition systems can direcfiybe deployedin practicaladverse environments where distant- talkingsound pickup is required.No retrainingnor modification of therecognizers is necessary. MANN consistsof twosynergistic components:(1) signalenhancement by microphone arrays and (2) featureadaptation by neuralnetwork computing. High-quality soundcapture by the microphonearray enables successful feature adaptation by the neuralnetwork to mitigateenvironmental interference.Through neural n•t•x, ork computation, a rash:bed training and teatlng condition ia approxlmat•dwhich typically elevates performanceof speech recognition. Bolh computer-simulated andreal-room speech input are used to evaluatethe capability of MANN. Measurementsof isolated-wordrecognition in noisy,reverberant, and distant-talkingconditions show that MANN leadsto a word recognitionaccuracy which is within4%-6% of thatobtained under a close-talkingcondition in quiet. 10:30 2aSP6.Wideband microphone array for hearingaid preprocessing.Kung Yao (Elect.Eng. Dept., Eng. IV, 68-113,UCLA, Los Angeles,CA 91403-1594}, Sigfrid D. Soli (HouseEar Inst., Los Angeles, CA 90057), and DanKorompis (UCLA, Los Angeles, CA 91403-1594) Speechcommunication in environments with low signal/noise ratios (SNRs) is a primarycomplaint of thehearing impaired. Microphonebeam formation techniques provide an effectiveapproach to improvingSNR in theseenvironments. A novel, fixed 3244 J.Acoust. Soc. Am., VoL 96, No.5, Pt.2, November1994 128thMeeting: Acoustical Society of America 3244 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp microphonearray is beingdeveloped with user-controlled mainlobe spatial look direction and attenuation band(s), and with a flat frequencyresponse over the speech bandwidth. The array of R microphonesand L tapsper microphone maximizes energy concen- trationover a spatiallook regionand frequency band, subject to spatialand frequency constraints. Constrained maximization of w*Aw/w*Bwis required,where A andB arematrices specifying spatial and frequency factors, and w is theRL dimensionalweight vector.The constraining subspace is specifiedby thearray values, derivative values, and spatial directional constraints; w is obtained as thesolution of a tractableunconstrained full-rank lower dimensional generalized eigenvalue problem. Numerical and simulation resultsfor differentvalues of R andL andfor differentbandwidths will be reported,as well as resultsof preliminarylistening tests withnormally hearing and hearing impaired individuals. The feasibility of real-timeacoustic beamformers with arrays for hearingaids, andthe advantagesof thisscheme over conventional adaptive schemes will alsobe discussed. 10:50 2aSP7.A large microphonearray for outdoorsound propagation studies. DavidI. Havelock (Inst.for MicrostructuralSci., National ResearchCouncil, Ottawa, ON K1A 0R6, Canada) A soundfield propagating outdoors is perturbedby the turbulencein the atmosphere.To studythe fluctuationsdue to turbulence, thesound field is measuredsimultaneously at a largenumber of pointsusing a microphonearray. The array consists of 64 microphones whichcan be configuredin a varietyof geometriesranging from smallpatches of only a few squaremeters to an elongatedarray spanning700 m. Remote"satellite" arrays are also possible. The dataare collected and processed in a mobileequipment trailer. The microphones,electronics, data collection, and processing are described and practical aspects of deployingthe array are discussed. The designcriteria and example applications of the arrayare also discussed. 11:10-11:15 Break 11:15-11:45 PANEL DISCUSSION TUESDAY MORNING, 29 NOVEMBER 1994 BALLROOM B, 8:00 A.M. TO 12:00 NOON Session 2aUW UnderwaterAcoustics: Moderate-to-High Frequency Bottom InteractingAcoustics I Mohsen Badiey, Chair Code3240A, Office of NavalResearch, 800 NorthQuincy Street, Arlington, Virginia 22217-5660 Chair's Introduction---8:00 Invited Papers 8:05 2aUWl. The investigationof millimeterscale heterogeneity in CoastalBenthic Boundary Layer sedimentsusing microresistivityand x-ray imaging of "diver"cores. Peter D. Jackson(British Geological Survey, Keyworth, Notts NG12 5GG, UK), KevinB. Briggs (NavalRes. Lab., Stennis Space Center, MS 39529-5004),Robert Flint (BritishGeological Survey, Keyworth,Notts NG12 5GG, UK), MichaelA. Lovell,and Peter K. Harvey(Univ. of Leicester,Leicester LE! 7RH,UK) A micro-resistivityimaging technique, developed for use on 70-mm "half-round" slabbed core has been adapted for use with larger "diver"cores, 33 mmthick, 350 mmwide, and 440 mmlong. This resistivity technique is shownto havea resolutionof 5 mmand to operatein a mannerwhich is complimentaryto x-ray photography. Theoretical and practical examples are presented showing responsestoindividual heterogeneity suchas shells. The benefits of 3-Dinvestigations areexplored via numerical models are shown tobe beneficial even in coressuch as those above having a "flat"aspect ratio. The microresistivity method is shownto be particularly sensitivetolayered structures and the presence ofshells within the very high porosity surface layers in Eckernforde Bay (89% porosity 0-10 cmbelow sea floor). [Work supported by U.S. Navy.] 8:25 2aUW2.Correlation functions for sedimentacoustic properties. Kevin B. Briggs (SeafloorSciences Branch, NRL, StennisSpace Center,MS 39529) Modelsfor sediment volume scattering require knowledge ofthe correlation functions forsediment sound velocity and density (or porosity).High-resolution vertical correlation functions of these properties have been estimated using sediment porosity and com- pressionalwave velocity data measured vertically atregular, closely spaced intervals from diver-collected coresamples. Because the dataseries are truncated owing to a limitedcore length, the correlation functions were estimated using a first-orderautoregressive 3245 J. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3245 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp modeland autocorrelations were calculated with Burg'salgorithm. Correlation length estimates were from a varietyof shallow-water sites.Relationships between grain size and correlationlength are discussed. 8:45 2aUW3, Modeling the near-bottomseafloor. RobertD. Stoll (Lamont-DohertyEarth Observatory of ColumbiaUniv., Palisades, NY 10964) In mine countermeasures work and otherseafloor engineering applications, there are two distinctlydifferent classes of sediment propertiesthat play importantrules in objectdetection and sonarperformance•those that determineif an objectwill sink into the bottomor stayfully or partiallyexposed and thosethat control the penetrationof high-frequencysonar signals into the bottom.The abilityof theseafloor tosupport an object depends largely on shearing strength which is a nonlinear,large-strain property associated with plasticdeformation and complete disruption of thein-situ struclure. In contrast,the complex velocity (speed and attenuation) of low-amplitudegeeacoustic signals is a small-strainproperty that can be treatedto a goodapproximation using linear theories. Both classesof responseand their interectionare discussedusing insights gained from the Biot-Gassmanntheory. This theoryallows extrapolationfrom low- to high-frequencyresponse and examination of theeffects of variousparameters such as gas content and low overburdenpressure. In particularthe effect of recentlymeasured high attenuation and velocity gradients is discussedand a correlation betweenshear strength and shear-wave velocity is shown.[Work supported by NRL, CBBLSRP.] 9:05 2aUW4. Microstructuralmodeling of clay sedimentsin EckernfoerdeBay. Jack$. Kolle,Alan C. Mueller (QUESTIntegrated, Inc., 21414 68th Ave. S., Kent, WA 98032), and Jack Dyerkin (StanfordUniv., Stanford,CA 94305) A finite-elementmicrostructure analysis code was used to modelthe geeacousticproperties of shallowmarine clay sediments in EckemfoerdeBay which has been the subject of an intensivegeeacoustic and geetechnical study' (Coastal Benthie Boundary Layer-- SpecialResearch Program). Uniaxial strain and pure shear were applied to two-phasemicrostructure models with generalized, periodic plane-strainboundary conditions to generateanisotropic bulk andshear moduli. Analyses were carriedout on two lengthscales: clay microfabric(/•m) andgas-filled inclusions (ram). The claymicrostructure was modeled as a randomlattice of Illitc plateletswith a densityand porosityequivalent to averagevalues observed in shallowEckemfuerde Bay sediments.Saturated and dry framework moduliwere calculated and the effective medium velocities were compared with observedvelocities. The analysissuggests that shear wavcpropagation in thesesediments is notsupported by the frameworkstructure but by differentialcompression of fluid-filledpores. Radiographicimages of pressurizedcores containing gas-filled inclusions with dimensionsof a few millimeterswere alsoanalyzed. The analysisindicates a shearwave velocityanomaly related to the inclusionstructure. The calculatedeffective medium velocities are comparedwith analyticalmodels of spheroidalinclusions. [Work supported by ONR.] ContributedPapers 9:25 Eightundisturbed large-diameter (10. I-era) gravitycores, ranging in lengthfrom 13.5 to 50.5 cm, werecollected at the CBBL-SRPstudy site 2aUWS.A propagationmodel for wave motionin saturatedgranular southeastof PanamaCity, FL. The recoveredsediments varied from coarse sediments.M.H. Sadd,A. Gantam (Mech.Eng. and Appl. Mech. Dept., sandand shellfragments near the surfaceto fine/mediumsand at depth. Univ.of RhodeIsland, Kingston, R102881), A.J. Silva (Univ.of Rhode The Multi SensorCore Logger was usedto measurecompressional wave Island,Narragansett, RI 02882), and G. E. Veyera (Univ. of Rhode velocity,density, and attenuationas a functionof depthin eachof the Island,Kingston, RI 02881) unsplitcores in two mutuallyperpendicular directions. Two spring-loaded Wave propagationin saturatedgranular sediments is modeledthrough compressionalwave transducersoperating at 500 kHz, mountedon the discreteelement simulation. The sedimentsunder study are assumedto be outsideof the liner, were usedto measurevelocity and attenuation,and a primarily sandy,and are thus modeledas cohesionlessgranular material Cs-137 gammaray sourcewith scintillationcounter were usedto measure saturatedwith pore fluid. Numericalsimulation is basedon the discrete bulkdensity. In thelongest of thecores, PC-GC-623, compressional wave elementmethod, a numericalscheme employing a modelingstrategy to velocityvaried between 1700 and 1730 m/s in the upper10 cm and be- determinethe translationaland rotationalmotion of all particlesin model tween1650 and 1700 m/s below that depth. Attenuation decreased slightly materialassemblies. For applicationto wave propagation,the movements with depth,with mostvalues falling between0.3 and0.5 dB/kHz/m(with of individualparticles are a result of the propagationof disturbances referenceto core liner filled with water).Density was relativelydepth- throughthe media. Contact laws between adjacent particles are constructed independentand ranged between 1.8 and 1.9 g/cm 3. usingelastohydrodynamic lubrication theory, and these relations determine the contactforce as a functionof the relativedisplacement and relative 9:55 velocity between neighboringparticles. Using these new contactlaws, wavemotion simulations of one-and two-dimensional computer-generated 2aUW7. Optimizing finite differenceschemes for wave propagation model assemblies have been conducted. Results indicate that the wave in high-lossviscoelastic materials, Mark A. Haynetand J. Robert speed and amplitude attenuationare functionsof the physical microstruc- Fricke (Dept. OceanEng., MIT, Cambridge,MA 02139) tureor fabricof thediscrete medium. Wave speed is inverselyrelated to the An optimizationtechnique is discussedwhich improves the numerical porosityof the solidphase, while attenuationstudies indicate that a branch efficiencyof thefinite difference method with memoryvariables used to vectordistribution correlates with interparticleforce transmission. Model analyzewave propagation in high-lossmaterials [r/=O(1)] [Blanchet al., developmentand simulationresults will be presented. "Viscoelasticfinite difference modeling," Rice UniversityTech. Rep. TR93-04(1993)]. With the conventionaluse of memoryvariables, the relaxation function of a viscoelastic material is modeled with a series of decayingexponential functions. The amplitudesand relaxation times of 2aUW6. Acoustical properties of undisturbed sands from the West theseexponentials are then matched, as closely as possible, to thebehavior Florida sand sheet. HorstG. Brandesand ArmandJ. Silva (Dept. of of the viseoelasticmaterial. Using the new optimizationtechnique, the OceanEng., Univ. of RhodeIsland, Narragansett, RI 02882) errorof thefinite difference method, which is completelypredictable using 3246 J. Acoust.Soc. Am., Vol. 96, No.5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3246 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp the von Neumanmethod, is accountedfor duringthe matchingprocess accountedfor by adoptinga conventionthat amountsto introducinga reducingthe totalerror. For narrow-bandmodels, the reoptimizationpro- complexquiescent density. cesscan reducerun timesand memoryrequirements for 2-D modelsby about8X and4X, respectively.The usefulnessand accuracy of this tech- 11:15 nique versusanalytic methods are demonstrated. 2aUWll. Acoustic backscattering by the anisotropic and dipped 10:10-10:30 Break structure of velocity fluctuations within the bottom sediments. TokuoYamamoto (Appl. Marine Phys.Div., RSMAS, Univ. of Miami, Miami, FL 33149) 10:30 The three-dimensionalpower spectra of thevelocity fluctuations within 2aUW8. The effectsof a thin slow sedimentlayer on shallow water the seabedmeasured by high-frequency(1-50 kHz) crosswellacoustic acousticfield. E.C. Shangand Y. Y. Wang (CIRES,Univ. of Colorado/ tomographyexperiments indicate that the velocityfluctuation spectra are NOAA/Environmental Tech. Lab., Boulder, CO 80303) anisotropicin generaland are oftendipped; i.e., the majorand minoraxes of anisotropyare tilted from the vertical and the horizontal direction The seabottomoften has a thin layer on its top and the soundspeed in (Yamamoto,this meeting).The aspectratio of the horizontalscale to the this thin layer is lessthan in water.It hasbeen found that this thin layercan verticalscale ranges from 4 to 10 in theshallo•-water sediments. The significantlyaffect the acousticfield in watercolumn. First, it changesthe angleof tilt, calleddip, is foundas largeas 30 deg.The intensityof the bottomreflection character, and, on the other hand,it changesthe modal fluctuationspectrum depends on the sedimenttype. These parameters of wave-numberdifference: D,•,, = 2rr(km -k,•) -•. Thosetwo factors deter- the three-dimensionalpower spectrumaffect the scatteringof acoustic minethe basicfeatures of the acousticfield--the modalinterference pat- waves.An analyticalsolution to acousticwave scatteringby a dipped tern and the modalattenuation rate. Basedupon the sensitivityanalysis, anisotropic3-D velocityfluctuations in the sedimentshas been obtained. bottomparameter estimation scheme is proposed. The strongdependence of acousticbackscattering on the grazingand azi- muthalangle observed by Jacksonand Briggs (1993) is excellentlypre- 10:45 dictedwhen the realisticanisotropy and dip structuresof the velocity fluctuationsare incorporatedin thisanalytical model of scatteringby sedi- 2aUW9. Consistent geoacoustic models in the frequency range mentvolume fluctuation. [Work supported by ONR.] 50-5000 Hz. CharlesW. Holland, Peter Neumann, and Greg Muncill (PlanningSystems Inc., 7923 JonesBranch Dr., McLean,VA 22102) 11:30 The processof creatinga gcoacousticmodel begins with the processof 2aUW12. Influence of sediment transport events upon bottom definingthe dominantmechanisms that controlbottom interaction for the backscattering,Eckernfoerde Bay. DarrellJackson (Appl. Phys. Lab., frequencyrange and applicationof interest.For example,a geoacoustic Univ.of Washington,1013 NE 40th St., Seattle,WA 98195) and L.D. model that treatsthe seafloorreflection process might be much simpler Wright (VirginiaInst. of Marine Sci., Collegeof William and Mary, thana geoacousticmodel which treats bottom interaction (i.e., general GloucesterPoint, VA 23062-1346) N-static scatteringincluding reflection and backscatteringas special cases).The followingstep is to determinevalues for the parametersthat In Spring1993, oceanographicand acousticapparatus were deployed describethose physical mechanisms of importance.This is typicallyap- in EckemfoerdeBay, Baltic Sea.An instrumentedtetrapod recorded physi- proachedby a combinationof directmeasurements (e.g., core data), em- cal data,revealing turbidity events associated with resonantinternal waves. piricalmodeling {e.g., Hamilton relations [E. L. Hamilton,J. Acoust.Soc. Acousticbottom backscattering data at 40 kHz were acquiredsimulta- Am.68, 1313-1340(1980)]}, or by inversionthe acoustic data. The result neouslyand show features that correlate with the turbidityevents. Such a canbe testedby comparingthe geoacousticmodel predictions (used as correlationis surprisingas estimatesof shearvelocity suggest that bottom primaryinputs to an acousticmodel) against measured acoustic data. stressnever reached the criticalmagnitude necessary to resuspendsedi- Geoacousticmodel predictions and comparisons with acousticdata and are ment;rather the turbidityevents appear to involveadvection from a distant givenfor a varietyof marineenvironments. A geoacoustic model that is location.Correlations are evidentin comparisonsof acousticallyderived successfullyemployed for bothseafloor reflection and scatteringis dem- time seriesfor changein temperatureand change in echocharacter with onstrated.[Work supported by theONR/AEAS Program.] time seriesfrom currentmeters, optical backscattering sensors, and ther- mistors.[Work supported by theNRL CBBL Special Research Program.] 11:00 11:45 2aUW10. Boundary conditions and the theory of acoustic attenuationin Iossyfluid seabeds. Grant B. Deane (Marine Phys. 2aUW13. Normal-mode description of reverberation with a finite Lab.-0238,Scripps Inst. of Oceanogr.,9500 Gilman Dr., La Jolla, CA area bottom patch average. J. LeMond (Appl. Res. Labs.,Univ. of 92093-0238) Texas at Austin, Austin, TX 78713) Duringthe lastdecade the traditional view thatacoustic attenuation in A normal-modereverberation model is presentedthat includes the ef- marinesediments is linearin frequencyfrom seismicto ultrasonicfrequen- fects of modal interferenceamong spatJelly correlated fields scattered cies hasbeen re-examined [A. C. Kibblewhite,J. Acoust.Soc. Am. 86, withina patchof (nearby)bottom locations. At eachfrequency the inte- 716-738 (1989)].In particular,there is a growingbody of evidencefrom gratedscattered field from a bottompatch as a functionof patchsize is theocean acoustic and marine seismology communities that the character- calculatedfrom an explicitnormal-mode expression. The time integrated isticsof attenuationin marinesediments are compatiblewith the Blot- reverberationlevel at eachfrequency is computedby squaringthis contri- Stolltheory for porousmedia. The Biot-Stollformulation predicts a range butionfrom each patch and summing over bottom patches. As a function of frequencydependencies, according to whichof a numberof attenuation of source/receiverseparation, the time integrated reverberation levels com- mechanisms,including viscous dissipation, is dominant.The questionof putedwith the finitepatch description oscillate about a meanthat is con- how different attenuation mechanisms can be accounted for in a fluid sistentlylower than the levels obtained in thezero patch area limit. Results descriptionof sedimentswill be examined.The conventionof complex from a studyof the dependenceof the level differencesand oscillation soundspeed does not accountfor all the effectsof absorptiondue to magnitudeson environment,frequency and patcharea are presented. viscousdissipation when quantities involving both the pressure and veloc- [Worksupported by theAdvanced Surveillance and Prediction System ity field are considered.An exampleof sucha problemis the Pekeris (ASAPS)Program of the Spaceand Naval Warfare Systems Command waveguidewith a 1ossybasement. The effect of viscousdissipation can be (SPAWAR,PMW 183-32).] 3247 d. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128th Meeting:Acoustical Society of America 3247 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp TUESDAY AFTERNOON, 29 NOVEMBER 1994 BRAZOS ROOM, 1:00 TO 5:00 P.M. Session2pAA ArchitecturalAcoustics: Performance and RecordingSpaces for Popular Music and Topicsin Isolationand Reverberation Richard E. Boner, Chair BonerAssociates, Inc., 200 East 30th Street,Austin, Texas78705 Chair's lntroduction•l:00 Invited Papers 1:05 2pAAI. "...throughthe glassdarkly..." or designingfor the needsof travelinggroups in a multipurposeperforming arts facility. DanaS. Houglandand Edward L. Logsdon (DavidL. AdamsAssociates, Inc., 1701Boulder St., Denver,CO 80211) Predictingand designingfor the everchangingacoustic and electroacousticneeds of a travelingshow utilizing multipurpose performingarts facilities is an ongoingchallenge. Most communities cannot afford the luxuryof buildingand maintaining single- purposeperforming arts facilities. There' is a needto accommodatea variety of localor residentperforming arts groups, as well as travelingshows. Shows may range from simplelectures to Broadwayshow productions, as well as the everincreasingnumber of multimediaperformances. Measures to facilitatethe traveling show performances must be simultaneouslyunobtrusive when not in use, andreadily accessible to thecrew of eachtraveling show. The successes and failu. res of varioustechniques are presented and critiqued. 1:35 2pAA2.Popular music performance and acousticsin spacesdesigned primarily as sports halls. JackWrightson (WJHW, Inc., 13714 GammaRd., Ste. 110, Dallas,TX 75244) Largeindoor sports arenas have always served a secondaryfunction as venuesfor othertypes of entertainmentand as gathering spaces.The reasonsinclude available capacity to servelarge crowds, proximity to densepopulation centers, and the economicneeds of the facilitiesthemselves, which cannot afford to operateas a single-seasonsport franchise. The rise in popularityof the touring "rock acts"is examined,as well as othertypes of musicalpresentations, and some of the acousticalplanning considerations needed to reasonablysuccessfully accommodate the diverseacoustical needs of varioustypes of entertainmentin thesehalls are discussed. Examplesand lessonsfrom recentwork will be presented. 2:05 2pAA3. Current trendsin pop musicrecording facilities. RussBerger (RussBerger Design Group, Inc., 4004 Beltline,#110, Dallas, TX 75244) The designof currentrecording facilities is being influencedby severalfactors. The proliferationof digital signalprocessing equipment,signal acquisition, and storage media have sparked changes in theway recordingstudio facilities are used.The mixtureof programmedsynthesis with acousticstudio performance and the resultingchanges in recordingtechnique also provide a significant influenceon the designof pop musicrecording facilities. The impactthese changes are having on facilitylayout, configuration, and function; noise and vibration control; the architecturalacoustic environment of studiosand control rooms;and the electroacoustic interface will be discussed. ContributedPapers 2:35 environment,and that the reverberationtime shouldbe somewhathigher thanthat of the "protestantchurch" curve as presentedin Acousticsby 2pAA4. Auditorium characteristicsand a cappellamusic. William •½ranck.[Work aupportcd by P,yan& Aaaociatc,s.] W. Ryan,Jr. (HardingUniv., Box 2239, Searcy,AR 72149-0001) Many authorshave presented the typicalcurves of •verberationtime 2:50 versusvolume for variousauditorium functions, such as religious, concert hall, opera,etc. Most of the religiouscurves suggest that the auditorium 2pAAS.Music critic listeningexperiment at Dallas' Meyerson SymphonyCenter--Aprogress report. David tubman (D. tubman & will bc usedfor instrumental(piano or organ)accompaniment of the sing- Associates, 14301 Middletown Lane, Westminster,CA 92683) and ing, whethercongregational or choir.This paperpresents the preliminary GaryW. Siebein (Univ.of Florida,Gainsville, FL 32611) resultsof a congregationalsurvey to discoverwhat the participantsof a cappellamusic desire. A plot of the reverberationtimes and volumesfor Professionalmusic critics often pass judgment on concerthall acous- the auditoriumsof the participatingcongregations is alsopresented. From ticsin theirreviews. Because of thewide circulation given to theirreviews, thesepreliminary results, it appearsthat the desireis for a more lively musiccritics may strongly influence public perceptions of the acoustical 3248 J. Acoust.Soc. Am., VoL 96, No.5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3248 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp meritsof concerthails. Surprisingly, no systematic study has been reported not a problemof a correctmeasurement procedure. It is far more the comparingcritics' acoustical judgments with thoseof musiciansand of descriptionof the soundinsulation itself in which problemsarise. The ordinarylisteners in the samehall, despiteits potentialvalue to both measuredor calculatedsound insulation is onlyvalid for the specificcase acousticaland critic communities.For this reason,the ASA launcheda under consideration. Numerical studies of the sound insulation of a flexible cooperativeeffort with the Music Critics Associationof North America partition(characterized by a limpmass) between two rooms show that the (MCANA).Its firststep was an informalexperiment at Dallas'Meyerson dimensionsof the sendingand receiving rooms have the mostimportant SymphonyCenter during MCANA's June 1994 meeting. The critics' meet- influence.This has to betaken into account when extending the frequency ingprovided a potentialopportunity to obtainacoustical assessments from rangein the standardsconcerning sound insulation which is necessary a significantnumber of criticsattending symphony concerts in thesame sinceneighbors low frequencystereo equipment, as well asthe all present hall.Standard survey forms and instructions were placed in theregistration traffic noise from outdoors,demands a sufficientsound insulationeven packetsof about75 musiccritics at check-in,and were distributedran- below 100 Hz. domly to about1000 volunteersattending concerts on two consecutive nights.Disappoinfingly, of 138 survey forms returned so far, only about 10 4:00 are from critics.This couldimprove by presentationtime. Surveyresults andlessons learned will be reported.[Work supported with privatedonor 2pAA9. Sound isolation-•A review. [lhuicamina Servln Rivas and TCAA TechnicalInitiative Funds.] (Academiade Acfistica,Escuela Superior de IngenierlaMec•inica y E16ctrica,Instituto-Polit6cnico Nacional, Laboratoristas No. 8, Colonia 3:05-3:15 Break Sif6n,Delegaci6n Iztapalapa, Mexico 09400 DF., Mexico) Whentreating the property of soundattenuation provided by partitions, 3:15 differentways are foundfor its specification.In this papermost common descriptorsemployed to specifyairborne and structureborne sound insula- 2pAA6, Acousticsof large homes. JamesE. Bruce,Charles T. Moritz, tion are summarizedand reviewed.Advantages and disadvantagesof andRobert D. Brace (Collaborationin Sci. andTechnol., Inc., 15835 Park single-numberspecifications for soundinsulation are commented upon. On Ten Place, Ste. 105, Houston,TX 77084-5131) the otherhand, emphasis is madeas to the importanceand convenience of Many largehouses (in excessof 5000 squarefeet) haverecently been field measurementsof sound insulation, even though they are time- built in the Houston, TX area. Some of these houses are constructedon consuming.Also includedis a brief descriptionof the situationprevailing speculationby buildersand some are designedand built for specificindi- in somecountries, Mexico amongthem, regardingminimum soundinsu- viduals.This papersummarizes the resultsof a surveyof the buildersof lation requirementsbetween dwellings. Finally, referenceis made to the bothtypes of homes.Since many individualswho build their own homes useof acousticintensity techniques for the measurementof soundinsula- designinto their spaces features that reflect their personality and needs, it tion andthe needof standardizationon this type of evaluation. wasthought that it wouldbe interestingto investigateif "goodacoustics" were one of thesefeatures. In addition,measurements of background 4:15 noise,reverberation time, noisereduction between critical spaces, and the noisereduction from outsidesources will be discussed.Finally, sugges- 2pAA10. Initial tests in AT&T Bell Labs' Varechole Chamber. tionsfor improvingthe acousticsof largehomes will be presented. William C. Ward (WARD Lab., 2441 CaminoCapitan, Santa Fe, NM 87505), GaryW. Elko, RobertA. Kubli (AT&T Bell Labs.,Murray Hill, NJ 07974), and W. Craig McDougald (AcousticSystems, Austin, TX 3:30 78764) 2pAA7. Computer-based system for reverberation room design. Resultsare available for the first measurementsin the recently com- EduardoM6ndez Castafieda (lngenieria Acfstica Spectrum, S.A. de C.V., pletedVarechole chamber, a digitallycontrollable variable acoustics facil- Apaseoel Alto 21-2, SanBartolo Atepehuacfin, Del GustavoA. Madero, ity atAT&T Bell Laboratories in Murray Hill, NJ. The 118 m 3 (6.7X6.1 M6xicoDF., CP 07730, Mexico) X2.9 m) room has 368 independentlyactuated surfaces in the walls, A simple computersystem named SIDIART developedin QBASIC ceiling, and floor. The room boundaryconditions can be completely languageis proposed,which permitsthe manipulationof a databaseof changedin a fractionof a second.This chamberis a uniquefacility for materialsand their respective absorption coefficients, making their election acousticalmeasurements, testing of electroacousticand signalprocessing easy. Knowing the volume and the areas,if the user wishes,the system systems,perception tests, or for recording.The panelsfrom which it is suggeststhe optimal500-Hz reverberationtime (RT) from one of ten constructedcould be appliedin multipurposerooms, recording studios, or optionaltypes of rooms.The Sabineor Eyring equations,and relative performancespaces. Reverberation time in the 750-Hz octave band is humiditybetween 10% to 90% for the calculusof air absorption,can be variablefrom 0.1-1.6 s; thistalk will presentfull 1/3-octdecay rates of the chosen.Given a numberof surfaces,its areasand a groupof candidate room.Some interesting impulse responses, and comparisonswith image materialsfor eachsurface, the systemreports the ratiobetween the optimal model calculations,will also be given. andcalculated RT for eachpossibility and for eachfrequency. The system hasthe option of searchingand reporting only the combinationthat offers 4:30 deviationsfrom the optimalRT definedby the useras acceptable,if that combinationexists. The algorithmof searchis basedon the traditionalway 2pAAll. Developmentsin the "chopper"theory of rotatingdiffuser to solvethe problemwithout a computer.The advantageof the system sidebandproduction. David Lubman (D. Lubman&Associates, 14301 takesroot in the velocityof calculusprovided by the computer;however, Middletown Lane, Westminster,CA 92683) the final resultof the projectdepends upon the designer. Periodic motion of a soundreflector in a tonally excited reverberant soundfield resultsin a multitonalreverberant spectrum consisting of sym- 3:45 metrical"sidebands" centered around the forcingfrequency. This surpris- ing and usefulphenomenon does not violate linear systemtheory! It was 2pAA8. Sound isolationat low frequencies,only an extensionof the firstreported in 1968,late in the historyof whatsome consider to be the traditionalfrequency range? Tot Kihlman (Dept. of Appl. Acoust., "mature" field of architectural acoustics. It was discovered in connection ChalmersUniv. of Tech.,S-412 96 Gothenburg,Sweden) with the inventionof rotatingdiffusers (RDs}, which were themselvesa The cxpr•:iion "low fr•qucmcic;a"implica a frequencyrange v,'h•r• the; aurpri•e.(Moving diffu•er• w•r• •hown to be the only cla• of dlffu•r that rooms'dimensions are comparablewith the wavelengthof soundin the canimprove spatial uniformity of reverberantsound.) Interest in RDswas rooms.In thisrange (below 150 Hz for normalroom sizes) the sound field spurredby their abilityto improvethe precisionof tonalsound power in therooms consists of a few modesonly, and changing of parametersthat determination in reverberation rooms. But neither the reason for multitonal are not connectedto the partitioninfluences the soundinsulation. This is "sidebands"nor theirrole in improvingspatial uniformity was understood. 3249 J. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November 1994 128th Meeting:Acoustical Society of America 3249 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp Someworkers pronounced sidebands to be trivialdoppler shifts. Others 4:45-5:00 deniedtheir very existence, dismissing data as mereillusions of reactive sound.At the recentSabine Centennial, this writer proposed a new "chop- PANEL DISCUSSION: Compatibilityof PerformingSpace• for Popu- per"hypothesis to accountfor RD sidebands.More physically compelling lar Versus Class'cal Music thanthe doppler hypothesis, it shows slxong potential for analyticaldevel- Panel Moderator: Richard [loner opment,and may facilitateRD designoptimization. Chopper theory is Panel Members:Russ Berger, Dana Hougland, Ed Logsdon,Jack reviewedand recentdevelopments are reported. Wrightson TUESDAY AFTERNOON, 29 NOVEMBER 1994 SABINE ROOM, 1:40 TO 4:55 P.M. Session2pAO AcousticalOceanography and Animal Bioacoustics:Effects of Soundson Marine Mammals: Update and Discussion on the Need for Standards I James H. Miller, Chair Departmentof Electricaland ComputerEngineering, Naval PostgraduateSchool, Monterey, California 93943 Chair's introduction•1:40 Invited Papers 1:45 2pAO1.A reviewof the effectsof soundon cetaceans.Adam S. Frankel (Dept.of Oceanogr.,Univ. of Hawaii,1000 Pope Rd., Honolulu,HI 96822) and ChristopherW. Clark (CornellBioacoust. Res. Prog., Ithaca, NY 14850) Studies to determinethe effects of various acousticstimuli on whales are reviewed, with an emphasison those studiesthat quantifiedsound level. Most of thesestudies have tested the effects of anthropogenicsound on bowheadand gray whales, with some work on otherspecies. The variablesused to measurethe whales'response to soundtypically include course deviations and changes in ratesof respirationand other behaviors. Examples include the relationshipof receivedlevel with theprobability of avoidanceof the soundsource [Malme etaL, MMS Rep.(1983, 1984}] and changes in respirationrate after the beginning of a soundplayback [Richardsoneta!., Mar.Environ. Res. 29, 135-160(1990)]. Response thresholds for continuous sounds have typically been measured at 110-124dB, with responsesto orca"screams" near 0 dB S/N ratio[Malme et aL, MMS Rep.(1983)]. These studies have led to theuse of the 120-dBlevel asa regulatorycriterion for ectaceandisturbance. The resultsof thesestudies will be presentedconsidering which variablesmay be importantfor determiningor predictinga whale'sresponse to sound. 2:05 2pAO2. MMATS: AcousticIocalizat'on of whalesin real time over large areas. David S. Clark (NRaD, San Diego, CA 92152-5000), JohnFlattery (ORINCON Corp.,San Diego, CA 92121), R. Gisiner (NRaD), I.. Griffith (NRaD), J. Schilling (ORINCON}, T. Sledzinksi (ORINCON}, and R. Trueblood (ORINCON) The marinemammal acoustic tracking system (MMAT) providesreal-time display and signal processing of ten channelsof acousticdata. In thisstudy analog signal data from ten Sohobuoyswere radioed to a circlingaircraft carrying the MMATS hardware; the datawere txansformedinto an intensity/time/frequencydisplay scrolling in real time. Whalespecies were determined from the signalcharacteristics; the systemincludes a neuralnetwork for automateddetection. Arrival time delaysof a signalat threeor more siteswere usedto localizethe whale.Acoustic identification and localizationof the whaleswere visuallyconfirmed by observem makingan independentvisual survey of Ihe areaat the sametime. Acoustic monitoring capabilities of the typeprovided by MMATS can significantlyreduce the numberof whalesmissed by traditionalvisual-only monitoring and provides a meansof calibratingboth methods,reducing the statistical uncertainty of populationestimates made using either technique alone. Because MMATS canmonitor large areasfor long periodsof time, it is well suitedto monitoringthe effectsof manmadenoise on the activitiesof whales. 2:25 2pAO3. Acousticdetection and location o! blue whales (Bataenopteramusculus) from SOSUS data by matched filtering. KathleenM. Stafford(Hatfield Marine Sci. Ctr., Oregon State Univ., Newport, OR 97365), ChristopherG. Fox (Natl.Ocean. and Atmos.Admin., Newport, OR 97365),and BruceR. Mate (OregonState Univ., Newport, OR 97365} Bluewhale calls were recorded off centralCalifornia in theFall of 1993.These calls were characterized asto duration,frequency downsweep,intercall interval, and sound-pressure level. Average values were determined from 303 calls,including up to three harmonics(fundamental downsweep from 18.9to 17.2Hz over 16 s}. Thesefrequency-domain characterizations were then used to developnumerical time series (kernels) that, when convolved with the original time series, produce correlation peaks indicating the presenceof bluewhale calls (matched filter). When harmonics were present in Ihedata, a combinedkernel, including the fundamental frequencyand first harmonic,improved the signalto noiseratio over useof the fundamentalkernel alone. These matched filters were ableto detect blue whale calls even in very "noisy" time series. When applied to hydrophone recordings from three U.S. Navy SOSUS (SOundSUrveillance System) arrays, it is possibleto producelocations for blue whale calls by timing the arrival of individualcalls 3250 J. Acoust.Soc. Am., Vol. 96, No.5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3250 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp andapplying least-squares techniques. This information can be usedto increaseour knowledge of bluewhale distribution in the northeastPacific. The methods described here may also be extended to otherspecies that employ low-frequency vocalizations or to other ocean areas. 2:45 2pAO4.Effects of boatnoise on the acoustic behavior of humpbackwhales. Thomas F. Norris (Dept. of VertebrateZoology, MossLanding Marine Labs., P.O. Box 450, Moss Landing, CA 95039) Theeffects of boatnoise on cetaceanacoustic behavior are not well understood.To examinethese, real sources of boatnoise were experimentallyintroduced to singinghumpback whales (Megaptera novaeangliae). Humpback whales were chosen as subjects because theysing long songs that are easy to record.Also, they are often distributed in nearshoreenvironments with heavy boat traffic. Songs fromnine animals were analyzed (n =9). Tenvariables describing time and frequency characteristics of humpback song signals and the structureof songpatterns were compared before and during exposure to boatnoise. Means of two variables(unit durationand phraseduration) were significantly less during boat passes than during control periods. Means of eightother variables were not significantlydifferent. The statisticalpower of detectinga difference between the means was >90% for all variablesdescribing frequencycharacteristics of songs. Because the durations of somevariables were shortened, these results indicate that boat noise might affecthumpback whale singing behavior. However, power analyses indicate that frequency structure is probablynot affected. The significanceof theseeffects concerning the behavioral biology of humpbackwhales is uncertainat thistime. 3:05 2pAO5.Temporal and spatialdistribution of whalecalls off Monterey,California. KhosrowLashkari (MontereyBay Aquarium Res. Inst., Pacific Grove, CA 93950) Twenty-sevenhours of acousticdata were recorded from a horizontalarray in deepwaters off thecentral coast of California.These data were analyzedto determinethe characteristicsof diverseunderwater acoustic sources. Some of the identifiedsources were: mooredRAFOS sources at rangesof 150-1000kin, low-frequencyship and machinery noise, and sounds of biologicalorigin. Over 400 whalecalls were identified and analyzed to determinethe distribution of thesecalls in bothtime and azimuth. Spectral analysis of thevocalizations indicate that most of thecalls were from humpback whales. [Work supported by theUnited States Navy, Naval PostgraduateSchool, and Monterey Bay Aquarium Research Institute.] ContributedPapers 3:25 correlationbetween the cumulativenoise exposure of the whole animal population,and the changein populationnumbers and overall health.Cur- 2pAO6. The influenceof acousticsignals on a juvenile gray whale. rently,the mostdifficult part of this analysislies in determiningthe sound PeterJ. Rovero, RobertM. Keolian, and JamesH. Miller (Code PH/Kn, Naval PostgraduateSchool, Monterey, CA 93943) exposureof the populationsince both the animalsand the noisesources are spatiallyand temporally varying. There is a certainamount of knowledge In May 1994,a juvenilegray whale,Eschrichtius glaucus, entered the aboutthe movementof both the noise sourcesand the population;this PetalumaRiver, which empties into the northend of San FranciscoBay, knowledgecan be usedto createa kinematicsimulation of the motionsof CA. The Marine Mammal Center of Sausalito,CA, coordinateda rescue bothentities. Such a simulationhas been used to yield long-termspatial and askedus to lure the whale to deeperwater with sound.The Petaluma probabilitydistributions of noisesources that can thenbe superimposed Riveris muddyand brackish, 20 km long,and generally 75 m wide and3 oversimilarly obtained distributions of the population.This superimposi- to 4 m deep.Recorded gray whale calls and synthetic signals in the range tion yieldsthe requiredestimates of the total noiseexposure of the popu- of 100-900 Hz werebroadcast with a J-9 acoustictransducer providing a lation. sourcelevel of 153 dB re: 1 /xPa at 1 m. Over severalhours, the whale, who surfacedfor air every 140 s, seemedto be attractedto thesesounds as we traveledat a few knotsdown river, our soundboat typically 50 m ahead of the whale.The whale appearedto loseinterest in the soundboat much 4:10 beyond100 m. A split stepparabolic equation model of acousticpropaga- 2pAO8. Low.frequency hearing in California sea lions and harbor tion in the river suggeststhat the soundlevel was 123 dB near the river bottomat a rangeof 50 m and120 dB at 200 m. On oneoccasion the whale seals. David Kastak (LongMarine Lab., 100 ShafferRd., SantaCruz, CA 95060) and Ronald J. Schusterman (California State Univ., approachedto within 3 m of the active source.The soundlevel at this distance would be about 144 riB. Hayward,CA 94542) Studieson pure-tonedetection thresholds were conductedon two fe- 3:40-3:55 Break male California sea lions and on a harbor seal. The older sea lion and the harborseal were trained to wear custom-fittedheadphones in order to 3:55 determineminimum audible pressures in a binaurallistening task. All three animalswere trainedto respondto underwatersignals at frequenciesrang- 2pAO7. A procedurefor the calculationof the noise impacts from a ing from 100-1600 Hz at a depth of about 1.5 m. Resultswere very spatiallystochastic source. RodolfoT. Arrieta (SpectrumSciences and reliable,owing to a combinationof psychophysicalthreshold determining Software,Ft. Walton Beach, FL 32547) measures.Sensitivity to low-frequencysounds by bothspecies were 25-30 Thereis growingconcern over the impactof humanintrusion into the dB betterunderwater than in air. The low-frequencyhearing of the harbor habitat or certain wild animal species.A major part of this intrusionis in aeal wa• 2-25 dB better than the older aeal lion. At 100 Hz, the aenMtivity the form of noisefrom movingvehicles. The level on the groundor un- of the harborseal was 17 dB superiorto that of the youngerseal ion, and derwatercaused by movingnoise sources has been dealt with as single- 23 dB superiorto theolder seal lion. Resultsat low frequenciessupport the event intrusionsthat may causestartle and associatedphysiological re- notionthat the harborseal (phocid) ear is morewater adaptedthan the sea sponses,and as cumulativenoise exposures. The later approachallows lion (otariid) ear. 3251 J. Acoust. Soc. Am., Vol. 96, No. 5, Pt. 2, November 1994 128th Meeting:Acoustical Society of America 3251 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 4:25 4:40 2pAO9. Behavioral responseof migrating gray whales (Eschrichtius 2pAO10. Acousticallyenhanced bubble growth at low frequencies robustus) to acoustic stimuli along the central California coast. and its implicationsfor human diver and marine mammal safety. Nicole M. /Magiel (Schoolof Fisheries,Univ. of Washington,WH-10, LawrenceA. Cramand Yi Mao (Appl.Phys. Lab., Univ. of Washington, Seattle, WA 98195) Seattle, WA 98105) The graywhale (Eschrichtius robustus) migrates close to shorealong the centralCalifornia coast, and is easily observablefrom laud. The ob- Computationsare madeof the conditionsnecessary to obtainbubble jective of thisstudy is to determinethe effectsof low-frequencysounds on growthby rectifieddiffusion under a varietyof conditionsassociated with gray whale behavior.A J-15 transducerwill be usedto projecttones of low-frequencysound propagation in the ocean.The complexissue of mi- varyinglow frequenciesand intensities from a vesselplatform located off ' crobubblenuclei stabilization is treatedby assumingeither a sufficient the coastof centralCalifornia. Gray whaleswill be observedfrom shore levelof supersaturationto stabilize the initial bubble size, or by examining duringthe south and northbound migrations past this region, in thepres- a microbubblenucleus with zerosurface tension. The bubble growth rates ence and absenceof soundproduction. Observed behaviors will then be andthresholds are obtained for a rangeof SPLs(re: 1/xPa) from 150-220 comparedand any disturbancedue to soundwill be determined.Results of dB, for initial bubbleradii from 1-10/xm, andfor levelsof the dissolved this experimentwill be importantin regulatingfuture sound-producing gasconcentration from 100% to 223% of saturation.It was determinedthat activitiesalong the graywhale migration route. This studywill alsohelp for the rangeof conditionsexamined, it was necessaryto utilize three resolvesome of the controversyover anotherexperiment known as the differentformulations of the equationsfor bubblegrowth. The resultsof acousticthermometry of oceanclimate (ATOC). The ATOC programin- thesecalculations and assumptions indicate that for SPLsin excessof 210 volvesthe projection of low-frequencysounds at higherintensities to mea- dB, significantbubble growth can be expectedto occur,and divers and surechanges in theocean temperature over extended time periods. One of marinemammals exposed to theseconditions could be at risk. For SPLs the soundprojectors for ATOC is proposedto be placedoff the central belowabout 190 dB, however,significant bubble growth is unexpected. Californiacoast and within the auditory range of migratinggray whales. [Worksupported in part by NSMRL.] TUESDAY AFTERNOON, 29 NOVEMBER 1994 SAN ANTONIO ROOM, 1:00 TO 5:00 P.M. Session2pPAa PhysicalAcoustics: Sonoluminescence and SonochemistryII AnthonyA. Atchley,Chair PhysicsDepartment, Naval Postgraduate School, Monterey, California 93943 ContributedPapers 1:00 Recentadvances in the useof singlebubble cavitation [D. F. Gaitan 2pPAal. Transient, high-pressure solidification associated with et al., J. Acoust.Soc. Am. 91, 3166 (1992)]have made it possibleto examineboth the temporaland spectralcharacteristics of sonolumines- cavitationin water. RobertHickling (Natl.Ctr. for Phys.Acoust., Univ. cencc[B. P. Barberet al., J. Acoust.Soc. Am. 91, 3061(1992)]. Direct of Mississippi,MS 38677) comparisonof the spectraof single-bubblesonoluminescence to multi- Thevery high pressures (>1 GPa)that occur during the final stages of bubblesonoluminescence hasproved difficult, however, due to differences collapseof a cavitationbubble force the water in thevicinity of thebubble in experimentalconditions. Examination has begun of bothsingle-bubble wall briefly(--1 ns)into a metastablestate of subcooling,relative to the andmultibubble sonoluminescence spectra of variousaqueous solutions equilibriumphase diagram. Estimates show that the subcoolingcan fall underclosely similar conditions, where, in a systematicway, a varietyof belowthe critical temperature for homogeneous nucleation of freezingand dissolvedgases, volatile organic liquids, and involatile inorganic salts have that high-pressureice particlesform at a sufficientrate to affectthe col- beenintroduced. Qualitative comparisons of thesespectra will be dis- lapse.Because of thegreater density of high-pressureice, a suddendrop in cussed.[Work supported by ONR andNSF.] pressureoccurs that triggersa shockwave thatconverges at the centerof the compressedgas in the bubble.Such microshocks are believed to be the causeof the extremelyshort duration of the flashesof sonoluminescencc 1:30 (<50 ps) thathave been observed from single cavitafion bubbles. The occurrenceof transient,high-pressure solidification can explain different 2pPAa3. Effect of ambient pressureon sonoluminescencefrom a phenomenaassociated with cavitation, specifically the decrease in cavita- singlebubble. Bradley P. Barber (Phys. Dept., UCLA, Los Angeles, CA 90024) tion erosionand the increase•n sonoluminescenceas the overall water temperatureapproaches 0 øC, together with the nucleation of freezingby cavitationin subcooledliquids. A singleexplanation for suchdiverse ef- Thedynamic sound field pressure Pa requiredto generatesonolumi- fectsprovides strong support for thesolidification hypothesis. nesccnce(SL) froma singletrapped bubble is a littlehigher than the ambientpressure P0 (e.g.,P,• 1.2P0).Since the acoustic energy density is proportionalto thesquare of P• observationof SL at lowerdrive levels 1:15 wouldimply that even greater degrees of energyconcentration accompany the transductionof sound into light. Motivated by thisperspective, the 2pPAa2. Comparisonsbetween multibubble and single-bubble dependenceof SL onambient pressure is being measured. Light emission sonoluminescence.Thomas J. Matula, William B. McNamara,III, atP0=0.3 Arm has already been achieved. Pressures higher than an atmo- PierreD. Mourad,RonA. Roy, and Kenneth S. Suslick(Appl. Phys. Lab., sphereare also being investigated, especially with attempts tofind single Univ.of Washington,Seattle, WA 98195and Univ. of Illinois,Urbana, IL bubbleSL in liquidsother than water. [Work suppotted by theU.S. DOE 6180•) Divisionof AdvancedEnergy Projects.] 3252 d.Acoust. Soc. Am., VoL 96, No. 5, Pt.2, November1994 128thMeeting: Acoustical Society ofAmerica 3252 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 1:45 3:00 2pPAa4.Time scalesfor sonoluminescence.Keith Wcninger,Robert 2pPAaS.Compressibility in bubble dynamicsand scattering. Paul Hiilcr, SethPutterman, and BradleyP. Barber (Phys.Dept., UCLA, Los E. Barbone,All Nadim,and Daniel Goldman (.Dept. of Aerospaceand Angeles,CA 90024) Mech.Eng., lI0 CummingtonSt., BostonUniv., Boston,MA 02215) The establishmentof stablesonoluminescence from a singletrapped The Rayleigh-Plessetequation describes the oscillations of a spherical bubbleof air in water requiresmore than 5 s. Duringthis time the bubble bubblewall underthe assumptionthat the fluid surroundingthe bubbleis goesthrough a transitionperiod (about I s long)that is characterized by an incompressible.Many modificationsof this equationhave been proposed emittedintensity which is overten timessmaller than the steadystate. Pure to incorporaleslight fluid compressibility,and thoughdifferent in form, noblegas bubblesturn on to their steadystate values on a muchshorter they are asymptoticallyequivalent. The differentforms of the equations, timescale (say less than 0.2 s). Duringthe transient period light from an air however,reveal remarkablydifferent properties.In some forms of the bubbleis wcakcrthan light from an Argonbubble but in the steadystate modifiedRayleigh-Plessct equation, for example,spurious unstable solu- the air bubbleis brighter.In view of the long time scalerequired for the tionsare presentwhile in othercases Ihey are not.Here, physicallymoti- establishmentof sonolumincsccncefrom a singlebubble of air it is con- vatedrestrictions on the form of the modifiedRayleigh-Plesset equation cludedthat this is a fundamentallydifferent phenomenon from the tran- are discussed.These restrictions are discussedin the contextof causality sient muMbubble sonoluminescence that has been studied since its discov- requiremenlSand higher-ordercorrections to the modifiedRayleigh- ery in 1934.[Work supported by the U.S. DOE Divisionof Advanced Piessetequation. EnergyProjects.] 3:15 2:00 2pPAa9. On asymmetrical motions of cavitation bubbles. Tao Shi and RobertE. Apfel (Yale Univ., New Haven,CT 06520-8286) 2pPAaS. Searching for an isotope effect in sonoluminescence. RobertA. Hiller andSeth Putterman (Phys. Dept., UCLA, LosAngeles, The phenomenonof sonoluminesencehas been of considerablerecent CA 90024} interestdue to a betterunderstanding of two typesof mechanisms:asym- metricalcollapse of transientbubbles and singlegas bubbleoscillation. The only pureliquids in which sonoluminescencefrom a singlestable Asymmetricalcollapse of transientbubbles result in lower sonolumines- bubblehas been observed are waterand heavywater. With regardto the cencetemperature; asymmetrical shape modes may alsodisturb the peri- contentof thetrapped bubble there are a numberof gaseswhich yield light. odic stabilityof singlegas bubbleoscillation. The boundaryintegral Heliumis particularlyinteresling because its spectrumis stronglypeaked methodhas been usedto studythe asymmetricalmotions of bubblesof in thefar ultraviolet.In orderto learnabout the mechanism responsible for initial diametersof 1-100/zm. The role of initial bubbleshape perturba- sonoluminescence,the searchis on for differencesbep.•een the spectraof tion, dissolvedgas saturation,surface tension, and maximumbubble size He4 andHe 3 bubbles inwater and heavy water. Other isotope pairs to be are observedup to a poinl where assumptionsconcerning the maximum comparedinclude hydrogen and deuterium.[Research supported by the bubble wall velocity and the internalbubble dynamicsare expectedto U.S. DOE Divisionof AdvancedEnergy Projects.] breakdown. It is observedthat the initial shapeperturbation grows when thebubble collapses and decays when it expands.Therefore, it appearsthat thereare circumstanceswhen cyclic singlebubble oscillations can occur 2:15 evenwith significant shape distortion. [Work supported by JetPropulsion 2pPAa6. Sonolumineseencefrom large plasma-inducedvapor Labthrough Contract No. 958722.] bubbles. Gary R. Hess,Ellis L. Loree, JamesD. Wieting, ForestE. White,and Chris M. Young (TetraCorp., Albuquerque, NM 87109-4512) 3:30 The lightemitted during Ihe collapseof largevapor bubbles has been 2pPAa10. An aspect of sonoluminescencefrom hydrodynamic theory. measured. The emission lasts for tens of microseconds and is so intense it H. Kwak,H. Yang (Mech.Eng. Dept., Chung-Ang Univ., Seoul, 156-756, mustbe filtered,under our experimentalconditions, to recordthe complete Korea),and J. Hong (OhsanTech. College,Ohsan, 447-749, Korea) time-dependentbehavior. The majorityof the energyappears to be emitted well below 630 rim. Such a long durationemission appears to be more Sonoluminescence(SL}, the phenomenonof light emissionassociated consistentwith adiabaticheating than shock phenomena.The temporal with Ihe collapseof bubblesoscillating under an ultrasonicpressure field shapeof the emissioncompares well with the temporalshape of the pres- hasbeen studied by solvingthe continuity, momentum (Euler), and energy sureproduced prior to andafter collapse,as well. Suchbubbles promote equationsfor the gas insidethe bubbleanalytically. Heat transferin the studyof the collapseprocesses in regionsof parameterspace which are liquid layer adjacentto the bubblewall hasalso been considered in this highlyaccessible. [Work supported by theU.S. Navy.] analysis.It hasbeen found that the gasbehavior is neitheradiabatic nor isothermalfor a bubbleunder ultrasound conditions. In this analysis,the launchcondition and the HugoMotcurve for the shockpropagation has 2:30-2:45 Break beenidentified, and the shockduration of 2.7 to 17 ps, whichis compa- rableto experimentalresults, has been obtained with the help of a simi- laritysolution (Guderley) for convergingspherical shock. For Sl, thegas 2:45 temperatureafter the shock focusing has been found to be 7000-44 000 K, dependingon the equilibriumbubble radius and the driving amplitudeof 2pPAa7. Numerical simulationsof single bubble sonolumioesceoce. ultrasound.It hasalso been found that the heatflux at bubblecollapse is as PierreD. Mourad (Appl. Phys.Lab., Univ. of Washington,Seattle, WA largeas 47 GW/m 2, which could be more than enough to cause an explo- 98195), Daniel L. Marcus (LawrenceLivermore Natl. Lab., Livermore, sionof an explosivecrystal. CA 94551), RonA. Roy,and Thomas J. Matula (Univ.of Washington, Seattle,WA 98195) 3:45 A higher-orderGodunov method is usedto solvethe sphericallysym- 2pPAall. Theoretical prediction of luminescencefrom acoustically metric,compressible Eulcr equations with an idealgas equation of stateas driven cracks. Ritva L/Jfstedtand Seth Putterman (Phys.Dept., UCLA. a model for Sl[Igte bubble sonolummescence.Basic sl•ock pl•ysics 1s diS- Los Angeles,CA 90024) cussedin this context,exploring how modeledvariations of the bubble interiorsupport or suppressthe generation and propagation of shockwaves Under the effectof an intenselong wavelengthsound field the lenglh within the bubble as well as the interaction of a shock with the bubble of a crack in a solid medium shouldoscillate. When the crack length is interface.[Work supported by ONR throughthe ONR/ARL program.] increasedthe imposedacoustic energy is focuseddown to regionsof 3253 J. Acoust. Soc. Am., Vol. 96, No. 5, Pt. 2, November 1994 128th Meeting:Acoustical Society of America 3253 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp atomic dimension so as to break the fundamental bonds which determine 4:00-4:15 Break the crystalstructure. It is suggestedthat this energycomes out as light whoseintensity is periodic with the sound wave. This analysis is based upon the elliptical model of a crack modifiedto includesurface tension. 4:15-5:00 [Worksupported by theU.S. DOE OffiCeof BasicEnergy Science, Divi- sionof Engineeringand Geophysics;R.L. is an AT&T Fellow.] PANEL DISCUSSION TUESDAY AFTERNOON, 29 NOVEMBER 1994 SAN MARCOS ROOM, 2:00 TO 4:15 P.M. Session2pPAb Physical Acoustics: Porous Media and Ducts Carl K. Frederickson, Chair NationalCenter for PhysicalAcoustics, University of Mississippi,University, Mississippi 38677 ContributedPapers 2:00 2:30 2pPAbl. On the use of probe microphone and level difference 2pPAb3.The influenceof pore-sizedistributions on complexwave measurements to characterize air-filled porous media. Carl K. number in air-filled porousmaterials. David W. Craig, Carl K. Fredericksoftand James M. Sabatier(Natl. Ctr. for Phys. Acoust., Univ. FrederickSon,andJames M. Sabatier(Natl. Ctr. for Phys. Acoust., Univ. of Mississippi,Coliseum Dr., University,MS 38677) of Mississippi,University, MS 38677) Air-filledporous media have been characterized acoustically using Probemicrophones have been developed to determinetortuosity and leveldifference measurements and an impedancemodel that depends on a effectiveflow resistivity for air-filled porous materials, such as agricultural pore-shapefactor, porosity, tortuosity, and bulk flow resistance.Least- soils.They are used to measurecomplex wave number as a functionof squaresfitting of level differencespectra only allowstwo of the above frequency.These data are then inverted using a single-pore-sizecapillary parametersto be independentlydetermined. Probe microphone measure- tubemodel for propagationin thematerial. However, the frequency de- mentshave been used to determinethe propagationconstant in both pendenceof themeasured wave number in sanddiffers from the predic- washedsand and glassbeads. Values of tortuositycalculated from probe tionsof suchsingle-scale models. It is shownthat distributions of pore microphonemeasurements were usedin the analysisof level difference sizescan producea similardependence. By summingover poresizes, datato determineporosity and bulk flow resistance.An averagepore-shape wavenumber as a functionof frequencyis calculatedfor lognormal,fractal factoris usedin the analysis.For the unconsolidatedporous media used, (power-law),and empirical distributions derived from porosimetry data. theeffect of thepore-shape factor variation was within the error range of Resultsare alsocompared with Wilson'srelaxation-matched fractal model the measurement.The availabilityof bothprobe microphone and level [D. K. Wilson,J. Acoust.Soc. Am. 94, 1136-11.35(1993)]. [Work sup- differencedata has also allowed for the comparisonof porosityand flow portedby USDA.] resistancevalues calculated from each set of data.There are some discrep- anciesbetween the frequencydependence of the modeland the probe microphonedata. [Work supported by USDA.] 2:45 2pPAb4.Sound propagation in capillary-tube-typeporous media: Effectsdue to the presenceof absorbedwater in the capillarywalls. 2:15 MiguelBernard and James M. Sabatier(Natl. Ctr. for Phys.Acoust., Univ. of Mississippi,University, MS 38677) 2pPAb2.Acoustic probe microphonemeasurements of Blot type I and II wavesin air-filledsands. CraigHickey, Wayne Prather, and Theeffects on sound propagation is investigated in air-filled capillary- JamesM. Sabatier(Natl. Ctr. for Phys.Acoust., Univ. of Mississippi, tube-typeceramic porous media that result from the presenceof small University,MS 38677) quantitiesof absorbedwater in thetube walls. Specific acoustic impedance measurementsare performedfor a rigid-backedsample for the casesof Probemicrophone measurements of air-borne sound penetrating into bothporous and nonporous tube walls. For the nonporous tube walls mea- air-filledsands and soils indicate two absorptioncoefficients for the fre- surementsare performed on dry andwater wetted walls. Preliminary re- quencyrange 40-4000 l-Iz. The probe microphone signal attenuates rap- sultssuggest a contributionto the increasedattenuation Of soundin the idlywith depth in a regionnear the surface. Below that region the micro- air-filledporous samples due to thepresence of a thinwater film. [Work phoneaignal attenuatca aignificantly alowcr with depth.Rigid-capillary- supportedin part by ONR.] tubeporous models, which allow for pore-fluidmotion only, correctly describethe rapid attenuation of probepressure. Using these models, pore properties(tortuosity and air permeability)are typically deduced from the 3:00 measuredcomplex absorption coefficient. The Biot poro-elastic-capillary 2pPAb5. Sound attenuation in a cylindrical tube due to tubemodel describes both attenuation regimes. The two absorption coef- ficientsare associated with the Biot type I andII waves.The large attenu- evaporation-condensation.Yi Mao andJames M. Sabatier (Natl. Ctr. for Phys.Acoust., Univ. of Mississippi,University, MS 38677) ationin theregion near the surface isassociated with the Biot type II wave. Themuch smaller attenuation coefficient is a consequenceof the elasticity The influenceof evaporation-condensationprocesses on the sound ofthe matrix and is associated withthe Bi0t type I wave. Biot's model is propagationin a cylindricaltube were studied in anattempt to understand usedto calculatethe microphone pressure from both Biot type waves as a thesound attenuation in porous materials. In thetheoretical model, the tube functionof depth.[Work supported by USDA.] wallwas rigid and kept a constanttemperature. A very thin layer of water 3254 J.Acoust. Soc. Am., Vol. 96, No. 5, Pt.2, November1994 128thMeeting: Acoustical Socie• of America 3254 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp on the wall wasallowed to evaporateinto or condensefiom the soundfield 3:45 propagatingin the tube. In additionto theacoustical, thermal, and vorticity modesin IGrchhoff'stheory, there existsa mass-diffusionmode. The 2pPAb8.Sound transmission in a pipe with developinglaminar flow: soundattenuation was obtained by applyingthe boundaryconditions on Upstream/downstreamphase speed differences. ChristopherL. thetube wall to thesefour modes. Analytic expressions for theasymptotic Moffey (Inst. of Soundand Vib. Res., Univ. of Southampton, behaviorsof bothhigh andlow-frequency limits werederived. While the SouthamptonSO17 1BJ, UK) and Malcolm G. Smith (Univ. of soundattenuation due to viscositycould be identified,those due to thermal Southampton,Southampton SO17 1BJ,UK) conductionand evaporation-condensation were coupled. The soundat- tenuationdue to theevaporation-condensation process would increase to In a uniformrigid-walled duct, plane waves propagate with axial phase a substantiallylarge level when the percentageof vaporin the tubewas speed(i_+M) timesthe sound speed, according to theinviscid plug-flow high,but it still underestimatedtheexperimental results in porousmateri- model.The difference between the downstream and upstream phase speeds als.[Work supported by ONR.] providesa measureof theflow rate;the sameconcept can be extendedto realisticprofiles of M (Machnumber) across the duct section, although the 3:15 lowest-ordermode is nota planewave any more. Calculations were carried outto providea meansof convertingphase speed differences to flow rates, 2pPAb6. Wave dynamicsand flow in multiple.porositymedia. assumingthat propagationis confinedto a singlelow-order mode (i.e., TimothyS. Marguiles(908 MarineDr., Annapolis, MD 21401) near-axialpropagation). The results were then compared with phase speed The purposeof thispaper is to describethe fluid flow anddynamics of measurementsmade in a cylindricalsteel tube, throughwhich air was wavepropagation in multiple-porositymedia (such as appliedto porous pumpedat a controlledsteady flow rate.Close but not perfectagreement rockwith fissuresof differentsizes). Coupled partial differential equations wasfound, which raises the questionof whetherour neglectof thermovis- for matrixdeformation and Darcy flow with compressiblemass conserva- cousphenomena is justified,particularly near the ductwalls. [Work sup- tionequations obtained from continuum mixture theory are developed. For portedby BritishGas.] thelimiting case of a singleporosity medium the transient response (pres- suredecay) solution for drillinginto a gassaturated rock layer, for ex- ample,that is homogeneous and isotropic, will bederived exactly by trans- 4:00 formationof the nonlineardiffusion equation describing the motions. Furthermore,a Burgers equation which admits soiltons will be presented. 2pPAb9.Propagation of soundin a lined circular duct with sheared Finallya generalizationto the caseof dual/triplecontinua will be treated. meanflow. JinlongWu andMark F. Hamilton (Dept.of Mech.Eng., Univ. of Texasat Austin,Austin, TX 78712-1063) 3:30 Thispresentation describes an analyticalinvestigation of thepropaga- 2pPAb7. Modeling sound propagationin a high porosityfibrous tion of sound in a lined circular duct with sheared mean ambient flow. The material. ChristopherL. Morley, Bradley P. Semeniuk,and Maurice mainassumptions are that the ambientflow is turbulentand unaffected by Petyt (Inst.of Soundand Vib. Res.,Univ. of Southampton,Southampton the sound,the Machnumber for the flow is smallcompared to unity,the SO17 1BJ, UK) thicknessof the viscousboundary layer is smallin comparisonwith the Soundpropagation in an air-filled,high porosityfibrous material in- radiusof the duct,and the acousticallining is locally reactive.The mean volvesthe elasticresponse of the fiber skeletonas well as thermaland flow profileaway from the wall is assumedto be uniform,but the profile viscous effects at the fiber-fluid boundaries. A theoretical model of wave within the boundarylayer can take one of severalanalytic forms. Outside propagationin sucha mediumhas been constructed based on the ideaof an the boundarylayer, the acousticmode structure is describedby Bessell equivalentfluid, which occupiesthe entire spaceand whoseproperties functions.The solutionwithin the boundarylayer is expressedin termsof approximatethe locally averagedproperties of the actualfluid. Once the Kummerfunctions, and the dispersionrelation is obtainedby matchingthe elastic propertiesof the skeletonare known•.g., from in vacuo inner and outer solutions,taking the wall impedanceinto account.The cxperiments-•themodel yields phase speeds, attenuation rates, and com- dispersionrelation is solved numericallyfor the attenuationand phase plex characteristicimpedances for both fast and slow wavesin the com- speedof the soundas a functionof modenumber, complex wall imped- positemedium. Typical results are presentedfor fiberglassblankets of the ance,boundary layer thickness,and flow profile within the boundarylayer. typeused as thermal insulation in aircraftfuselages. [BRAIN projectsup- Both upstreamand downstreampropagation are considered.Comparisons portedby theEuropean Commission.] are madewith publishednumerical results. 3255 d. Acoust. Soc. Am., Vol. 96, No. 5, Pt. 2, November 1994 128th Meeting: Acoustical Society of America 3255 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp TUESDAY AFTERNOON, 29 NOVEMBER 1994 CONCHO ROOM, 1:00 TO 4:35 P.M. Session2pPP Psychologicaland PhysiologicalAcoustics: Emissions, Localization, Rhythm, Masking, and More Ted L. Langford,Chair U.S. Army AeromedicalResearch Laboratory, Fort Rucker,Alabama 36362 Chair's Introduction--l:00 Contributed Papers 1:05 The primaryneurotransmitter for thecochlear efferent system is widely believedto be acetylcholine.If anticholinergicdrugs reduce neurotrans- 2pPP1. Studiesof the relationshipsbetween ear canal and cochlear mitter activityin the efferentpathway, they shouldproduce effects in signalsfor external tones and spontaneousand distortionproduct accord with those seen in animal studies where the olivocochlear bundle otoacoustic emissions, and their connection with middle ear (OCB) wassevered. Experiments were conducted to measureeffects of transmission.Carrick L. Talmadgeand Arnold Tubis (Dept.of Phys., threecommon anticholinergic drugs, diphenhydramine (Benadryl©), hyos- PurdueUniv., WestLafayette, IN 47907) cyamine(Levsin©), and scopolamine (Transderm-Scop ©)on two psycho- Some knowledgeabout the transmissioncharacteristics of the human physicaltasks and two physiologicalmeasures. There was no evidenceof middle ear may be obtainedby comparingear canal levels of external impairedperformance in a complexfrequency-discrimination task or in a tonesand spontaneousemissions of the samefrequency, which when used lateralizationtask using interaural intensity differences. Also, no compel- with anothertone give similarear canallevels of distortionproduct otoa- ling evidencewas found to indicatethat either spontaneous or click-evoked causticemissions. It is assumedthat the cochlearactivity patterns of an otoacousticemissions were enhanced by thesedrugs. After the beginning externaltone of frequencyf2 anda spontaneousemission of frequencyf2, of theseexperiments, a report appeared IS. G. Kujawaet al., Hear.Res. 74, whichproduce the same levels of earcanal cubic distortion products when 122-134(1994)] indicating that, in guineapigs, suppression of distortion- usedin conjunctionwith an externaltone of frequencyfl andfixed level, productotoacoustic emissions was reversedby anticholinergicshaving are very similar.The degreeof similarityis studiedusing nonlinear active antinicotinicaction, but lessso by thosehaving antimuscarinic action. The cochlearmodels that give spontaneousemissions [Talmadge and Tubis threeanticholinergic drugs used here are primarily antimuscarinic in their (1993)].The relationshipof thecochlear activities at theplace of peak action,which may explainthe failureto observethe predictedeffects. excitation and at the base of the cochlea is also studied in detail. The model [Worksupported by NIDCD.] resultsindicate that the comparisonof ear canallevels of externaltones andspontaneous emissions, which are equivalent with respectto thepro- 1:50 ductionof distortionproduct emissions, may be usedto give estimatesof the reflectionand transmissionof cochlearwaves at the stapes.[Work 2pPP4. Evidence for heritability and prenatal masculinizationof supportedby theDeafness Research Foundation.] cochlear mechanisms from measures of otoacoustic emissions. DennisMcFadden and John C. Loehlin (Dept.of Psychol.and Inst. for Neurosci.,Mezes Hall 330, Univ. of Texas,Austin, TX 78712) 1:20 Spontaneousand click-evokedotoacaustic emissions (SOAEs and 2pPP2. Wavelet analysisof transient-evokedotoacoustic emissions. CEOAEs)were measured in twinpairs of varioussorts---monozygotic JeffreyD. Travisand R. JoeThornhill (Appl.Res. Labs., Univ. of Texas (MZ), same-sexdizygotic (SSDZ), and opposite-sexdizygotic at Austin, P.O. Box 8029, Austin, TX 78713-8029) (OSDZ)--aswell as in nontwins.Comparison of the numberof SOAEs exhibitedby MZ andSSDZ twin pairs previously led to theconclusion that A novelapproach to findinginformation in transient-evokedotoacous- about75% of the individualvariation in SOAEexpression can be attrib- tic emissions(TEOAEs) was used:the discretewavelet transform.It is uted to genes.Parallel calculationswill be shownfor the CEOAE data. In arguedthat wavelet transformsare more appropriatethan fast Fourier accordwith pastsurveys, females generally exhibited more SOAEs than transforms(FF'Ts) for signaldecomposition because of the transient,non- males;however, OSDZ femalesexhibited, on average,less than half as stationarynature of TEOAEs. Severalwavelets were usedto obtaintime- manySOAEs as other females, and thus were comparable to maleson this frequencymaps of TEOAEscollected in pastexperiments. The latency of measure.Similarly, the strength of the CEOAEswas generally greater in severalfrequency bands can be clearlydetermined for anygiven subject femalesthan in males,but not in OSDZfemales. The interpretation is that withthis map. Another set of datacollected from an experiment in which thecochleas of OSDZfemales have been masculinized byexposure to the subjectswere administeredquinine sulfate was alsostudied. Quinine sul- highlevels of androgensproduced prenatally by theirmale co-twins. (Pre- fatesuppresses TEOAEs and induces some hearing loss [D. McFaddenand natalmasculinizing effects are well knownin othermammals.) If correct, E.G. Pasanen,J. Acoust.Soc. Am. 95, 3460-3474 (1994)]. Waveletanaly- the genesapparently lay a groundworkfor the expressionof ½mlaaion,5• sison thisdata revealed any temporal shifts of frequencybands during the and,correspondingly, good hearing sensitivity--and prenatal exposure to effect of the drug, and correlatedthe TEOAE waveformwith the amount androgensoperates to reduceboth emission strength and sensitivity. [Work of temporaryhearing loss at eachfrequency band. supportedby NIDCD.] 2:05 1:35 2pPP5.Individual differences in sensitivityto interauraldisparities 2pPP3. Effect of anticholinergicdrugs on human spontaneousand of timeand of level. TedL. Langford(U.S. Army Aeromed. Res. Lab., click-evokedotoacoustic emissions, frequency discrimination, and Fort Rucker,AL 36362) lateralization using interaural intensity differences. NarrimanLee Callawayand DennisMcFadden (Dept.of Psychol.,Mezes Hall 330, Thesensitivities of 22 womenand 23 mento interauraltemporal dif- Univ. of Texas,Austin, TX 78712) ferences(ITDs) in low-frequencynoise bursts and interaural level differ- 3256 J.Acoust. Soc. Am., Vol. 96, No.5, Pt.2, November1994 128thMeeting: Acoustical Society of America 3256 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp ences(ILDs) in high-frequencynoise bursts were measured in discrimina- applicationof standardpattern recognition methods. But buffering of high tion and absolutejudgment tasks. The discriminationabilities of both bandwidthsensory input is implausibleand problematical. An architecture groupsof observerswere symmetricalin that therewere no differencesin basedon the adaptive oscillator model [J. D. McAuley,J. Acoust. Soc. Am. pedormancebetween interaural disparities favoring either the right or the 95, 2966(A) (1994)]is presentedwhich generates a spatial pattern from left ear. The women were somewhat less sensitive and more variable in the rhythmiccontent of the acousticinput. The acousticsignal is passed their performancesthan were the men in both the temporaland level througha bankof gammatonefilters, each channel is half-waverectified difference discriminationtasks. However, the mean differencesbetween and downsampled, allowing a simpledifferencing procedure to identify thesexes, 28/xs and0.9 dB, werenot large compared with thevariability onsets,which serve as inputsto a 2-D arrayof oscillatorsorganized by acrossindividuals. Individuals who performedwell-discriminating ILDs frequencychannel and by intrinsicperiod. Each oscillatoradjusts its in- alsoperformed well with ITDs. Many observersexhibited ILD subjective trinsicperiod to matchperiodic onsets present in the signal.Only those midlineswhich were offsetto the left of objectivecenter in the absolute oscillatorsthat succeedin synchronizingtheir activityto a periodin the judgementtask. This effectwas unrelated to ILD discriminationability, to inputsignal produce persistant output. After synchronization,the output monauralthresholds, or to absolutejudgements based on ITDs. distributionproduces a stable spatial pattern over the 2-D array.The pro- cedureallows treatment of patterndistributed in time withoutrecourse to 2:20 sensorybuffering. Output patterns for a varietyof stimuli,including ani- mal gaits,musical rhythms, and prosodic structure will be presented.[This 2pPP6, Localizing broadband noise in a reverberation room. projectwas supported by ONR.] TimothyJ. VanderVelde,Millicent M. Ow, WendyR. Thorpe,William MorrisHartmann, and Brad Rakerd (Michigan State Univ., East Lansing, MI 48824) 3:05-3:20 Break Soundlocalization experiments were performed to determinethe rela- tive importanceof steady-stateinformation and onset-transient information 3:20 to the localization of broadband noise in a reverberant environment. Ex- perimentsused a sourceidentification method with an array of 24 speakers, 2pPP9. Contralateralstimulation and the maskingovershoot effect. separatedby 2 degof azimuth,in a reverberationroom (RT60•4 s). Noise ChristopherW. Turner,Rebecca Waite, Karolyn Cummings, and Melanie signalonsets were either abrupt, or slowlyramped, or entirelymasked by Rosen (SyracuseUniv., Program in Commun.Sci. and Disord. and Inst. othernoise. The ratioof directto reverberantsound was controlledby for SensoryRes., 805 SouthCrouse Ave., Syracuse,NY 13244) positioningthe listenerwith respectto the speakers.Data showedthat (1) localizationof soundwith abruptonsets is particularlyinsensitive to direct/ Overshootis the increasein maskedthreshold for a shortsignal pre- reverberantratio. (2) Slowlyramped onsets allow listenersto uselocaliza- sentedat the onsetof a maskercompared to the thresholdfor a signal tion information in the weak direct sound before the reverberant field has presentedin the temporalcenter of the masker.One hypothesisto explain fully formed.(3) Somelisteners (all young)have remarkable ability to thiseffect is the slowonset time for masker-stimulatedipsilateral efferent extractlocalization cues from apparently overwhelming reverberated noise activityto influencethe responseto the maskedsignal. Recent physiologi- whenonsets are masked. Further experiments suggested that these listeners cal experimentshave shown that noisepresented to the contralateralear, makeuse of cuesat high frequencieswhere reverberated sound is mini- whichprovides an incrementin efferentactivity, can increasethe neural mized by wall absorption;performance for theselisteners decreased dra- detectabilityof shorttones masked by noise[Kawase et al., J. Neurophys. maticallywhen the noise was lowpassed at5 kHz.[Work supported by the 70,2533-2549 (1993)]. The present behavioral experiment took advantage NIDCD.] of thesefindings and measured the amountof overshootunder conditions wherea brief contralateralnoise was presentedprior to the maskeronset, 2:35 in an attemptto "prime"the efferent system prior to themasker onset. All measurementswere conductedusing insert earphones, which provide ap- 2pPP7. Differential sensitivityto increasesand decreasesin tempo: proximately80 dB of interauralattenuation. The precedingcontralateral Evidencefor an entrainment model. J. Devin McAuley (Dept. of noisereduced or eliminatedthe overshootacross a wide rangeof masker Comput.Sci., CognitiveSci. Program,Indiana Univ., Bloomington,IN levels. Possible mechanisms for the overshoot effect will be discussed. 47405)and GaryR. Kidd (IndianaUniv., Bloomington, IN 47505) [Worksupported by NIDCD.] Listeners'abilities to detectchanges in tempowere investigatedwith two- andfour-tone isochronous sequences with interonsetintervals (IOI) 3:35 of 100, 400, 700, and 1000 ms. Separatethresholds were measuredfor increasesand decreases in tempousing an adaptive-trackingprocedure. On 2pPPI0. Effects of rise/fall time on maskeddetection thresholds and eachtrial a standardpattern was followed by two comparisonpatterns, one temporalintegration for noiseband signals. M. G. Heinz (Dept.of of which was fasteror slowerthan the standard.Listeners judged which Elec. and Cornput.Eng., JohnsHopkins Univ., Baltimore,MD 21218), comparisonpattern was differentfrom the standard.Consistent with pre- C. Formby (Univ. of Maryland Schoolof Medicine,Baltimore, MD viousstudies of tempodiscrimination, thresholds were foundto be lower 21201), and K. L. Mortimer (GeorgetownUniv., Washington,DC with four-tonesequences than with two-tonesequences, especially at the 20057) faster tempos.However, at the fastesttempos, listenersshowed greater Formbyet al. [J. Acoust.Soc. Am. 96, 102-114 (1994)] notedthat sensitivityto increasesthan to decreasesin tempo,while the reversewas maskeddetection thresholds (MDT) andtemporal integration (TI) for brief trueat the slowertempos. The crossoverpoint occurred at an IOI between noiseband signals may be influencedby the rise/falltime (RFF) usedto 400 and 700 ms. The findingsare consistentwith the predictionsof an gate the signals.Also, the definitionof signalduration (T), defined(1) entrainmentmodel [J. D. McAuley,J. Acoust.Soc. Am. 95, 2966 (A) exclusiveof RFT or (2) inclusiveof RFF, affectedtime constant0') esti- (1994)]in whichtempo sensitivity is reflectedby the degreeto whicha matesfor TI. In thisstudy, the role of RFT wasevaluated systematically systemof adaptiveoscillators is entrainedby the rhythm of a stimulus forsignal bandwidth (W=62-6000 Hz) andmasker conditions reported by pattern.[Work supported by NIMH andNIDCD.] Formbyet aL The MDTs were measuredfor a rangeof rise/fall time (RFF=l-40 ms) and plateau(P=1-20 ms) valuesto extendFormby 2:50 et al.'s originaldurations (T= P = 10-480 ms).In general,for a givenW and P condition,MDT decreasedand becameasymptotic with increasing 2pPPS. A novel architecture for rhythmic pattern recognition, Fred Cummins (Depts.of Linguisticsand CognitiveSci., IndianaUniv., RIvF. For a given W, the effect of RFF increasedas P decreased,and the effect was greatestfor small W. For P>•10 ms and R[•7•>l ms, MDTs Bloomington,IN 47405) were independentof Rl•17for all W. For T definedexclusive of RIW (i.e., The problemof patternrecognition in time is usually addressedby T= P), rwas inverselyproportional to RFF for W•<1000Hz and invariant buffering,which convertstime into a spatialdimension, and allows the with RFF for W>1000 Hz. For T defined inclusive of RFF (i.e., 3257 d. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November 1994 128th Meeting:Acoustical Society of America 3257 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp T= 2*RFT+ P), •' increasedmonotonically with RFT for all W. [Research amplitudeprocessor, then sent to thesaid modulator to restorethe dynamic supportedby NIH.] rangeof the speech.In comparisonwith the originalspeech, the resulting oneis of a little spectralenhancement, the intermodulation-distortion(ID), 3:50 andsome compression effect because of thenonlinear amplitude process- 2pPPll. A computational model of temporal integration. Nell P. ing. Towardsthe end of our research,the informallistening experiment McAngusTodd (Dept. of Psychol.,Univ. of Manchester,Manchester was performed,25 peoplewith sensorineuralhearing impairment who M13 9PL, UK) weartheir own hearingaids routinely participated in the experiment.The experimentresults have shown that 80% listenerspreferred the processed In thispaper a computationalmodel of temporalintegration is demon- speechto the originalone. This resultis quiteconsistent with one of our strated.The modelhas the following architecture. The firststage computes expectations:His losethe nonlinearactive characteristics to someextent, a representationof the auditorynerve response based on the Sheffieldear. therefore,introducing appropriately ID can help His to perceivespeech. The nerveresponse is summedand low-pass filtered with a temporalwin- dowof about10 ms[Plack and Moore, J. Acoust. Soc. Am. 87, 2178-2187 (1988)].In thesecond stage the summed and smoothed nerve response is 4:20 coupledto a transmissionline modelof auditorysensory memory. Close to 2pPP13. Acoustic characteristicsof voicelessplosives: For the the peripherythe impulseresponse of the transmissionline is sharp.As a improvementof consonantrecognition ability in cochlearimplant. pulse transmitsinto the systemthough, it becomesprogressively more KoichiOmori, Stanley M. Blaugrund(Ames Vocal Dyn. Lab., Lenox Hill attenuatedand spread out in time. In the thirdstage the line is tappedat Hospital,100 East77th Street,New York,NY 10021-1883), Hisayoshi differentpoints (approximately 10-ms spacing) and peak responses de- Kojima,and Kazuhiko Shoji (KyotoUniv., Sakyo-ku, Kyoto 606, Japan) tected,which then become input samples for higherorder leaky integrator with a time constant of about 200 ms. The model thus resembles the Recognitionof consonants,especially voiceless plosives, is inadequate "multiplelooks" model as proposed by Viemeister[Viemeister and Wake- in patientswho undergomultichannel cooblear implants. This studywas field, J. Acoust.Soc. Am. 90, 858-865 (1991)] and is able to accountfor undertakento ascertainacoustic characteristics of voicelessplosives/p/, the "resolution-integration"paradox. Quantitative predictions of the /t/, and /k/. Consonant-vowelsyllables /pa/, /ta/, and /ka/ of a normal modelare shownfor the temporalintegration example from the Houtsma, humanvoice were digitized,and processed by computerin threedifferent Rossing,and Wagenaarscompact disk. ways.First, a portionof consonantsignals was deleted.Second, a preced- ing consonantin onesyllable and a followingvowel in the othersyllable 4:05 werecombined. Third, vowel/a/was synthesizedby repetitionof the first 2pPPI2. Signal processing to improve speech quality for cycleof followingvowels, and was examinedby spectralanalysis. All hearing.impairedpeople. ZlatanRibic and Jun Yang (ViennatoneGes. processedsounds were perceivedby five experiencedlisteners. Each M.B.H., Fr/fbelgasse26-32, A-1164 Vienna,Austria) voicelessplosive was recognized correctly by itsprocessed syllables which hadat leasta I-ms signalof consonantfrom the onset. Following vowels A signalprocessing scheme is proposedto improvespeech quality for servedas a cuefor recognizingvoiceless plosives. In followingvowels, the hearing-impairedpeople (HI). In thisscheme, Hilbert transform and frequencyinformation, especially in the high-frequencyrange, was an vectorsum generator are usedto obtainthe Hilbert envelopeAM, and it importantfactor. From these results, recognition of a shortsignal at the followsa voltage-controlledamplifier (VCA) with thegain inversely pro- onsetof precedingconsonants and emphasis of high-frequencypower in portionalto AM, the outputsignal of VCA is sentto a modulator.On the followingvowels are essential for theimprovement of speechperception otherhand, AM is dynamicallyprocessed by a lowpassfilter and nonlinear of voicelessplosives in cochlearimplantation. TUESDAY AFTERNOON, 29 NOVEMBER 1994 PECOS ROOM, 1:00 TO 5:15 P.M. Session2pSA Structural Acousticsand Vibration: Energy Methods in Active Control Scott D. Sommerfeldt, Chair AppliedResearch Laboratory, Pennsylvania State University, P.O. Box 30, StateCollege, Pennsylvania 16804 Chair's Introduction--l:00 Invited Papers 1:05 2pSA1.Active control of flexuraland extensionalpower flow in beamsusing time domain wave vector sensors. Gary P. Gibbsand Chris R. Fuller (Vib.and Acoust. Labs., Dept. of Mech.Eng., Virginia Polytech. Inst. and State Univ., Blacksburg, VA 24061-0238) Activecontrol of beamvibration using power flow considerations hasbeen a topicof interestin recentyears. Traveling waves in structurescan be considered "carriers" of energy.For thin beams the magnitude of the energy carried by the wave is proportional to thesquare of the amplitudeof thetraveling wave. Thus if travelingwaves in structurescan be sensedin thetime domain then the correspondingpower flow will beestimated in thetime domain. In thispaper, a timedomain method for theestimation of flexuraland extensionalwaves in beamswill bepresented. The method uses a spatialarray of sensorsin conjunction with digital filters to estimate theseparate power flow associated with positive and negative traveling flexural and extensional waves. In anexample, surface- 3258 J.Acoust. Soc. Am., Vol. 96, No.5, Pt.2, November1994 128thMeeting: Acoustical Society of America 3258 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp -mountedPVDF sensors were used in conjunctionwith a digitalfilter network to estimate the traveling waves for bandlimited spectra. Experimentswhere conducted in whichthe simultaneous flexural and extensional power flow in semi-infiniteand finite beams was controlledusing the wave vector sensors and surface mounted piezoceramic actuators. These experiments demonstrate the control of beamvibration using power flow-based methods requires fewer actuators and sensors then corresponding modal control techniques. [Worksupported by NASALangley Research Center.] 1:30 2pSA2.Active structural vibration control via slidingmodes: Links to Lyapunovdesign. Shawn E. Burke (TheCharles Stark DraperLab., 555 Technology Square, Mail Stop 53, Cambridge, MA02139) and JohnE.Meyer (FailureAnalysis Associates, Menlo Park, CA 94025) A nonlinearactive vibration control design method is developedbased upon an extensionof variablestructure control (VSC) techniques,in particular sliding mode control, to distributedparameter systems. The temporal compensator design utilizes a gener- alizedwave equation representation of the plant. The control is implementedvia a seriesof decentralizedsingle-input/single-output (SISO)local loops around collocated transducers. Noa prioriknowledge of the temporal plant model is assumed, hence the resulting designsare insensitive to variationsin theplant modal frequencies. The equivalentcontrol reduces to outputvelocity feedback, a knownstabilizing control. Active damping performance is enhancedthrough the introductionof an additivenonlinear term which selectivelyincreases the velocity feedback control with a constrainednonlinear gain profile away from the zero-velocity phase plane origin.Stability constraints are discussed. For simplestructural components such as beams and plates, the design method yields controllersidentical to thosederived using Lyapunov's direct method, which extremize total system energy. Example controllers for beamsand plates are presented. In orderto demonstratethe application of thenonlinear control, closed-loop vibration control experimentson a 56- x59-in. nine-bayaluminum grillage are summarized. 1:55 2pSA3.Sensor location considerations foractive noise control in enclosures.John W. Parkinsand Scott D. Sommerfeldt(Appl. Res.Lab. and Graduate Program in Acoustics,Penn State Univ., P.O. Box 30, StateCollege, PA 16804) Minimizingthe squared pressure ata discretepoint(s) is one method of achievingglobal control in anenclosure, but this strategy willfail when the error sensor(s) lieclose to nodal planes of thepressure field. In thiscase, the secondary modes dominate the pressure measurement,and the active control will createa minimumwith little consideration given to thedominant mode. Subsequently, primarymode amplification may result, and the total potential energy in theenclosure will increase.A control based on energy density, on theother hand, can generally sense the dominant mode when the error sensor is closeto a pressurefield nodal plane, due to its dependenceon velocityas well aspressure. Nodal patterns of theenergy density field consist of nodallines and nodal points that lie on thepressure field nodal planes. At theselocations, energy density measurements will alsobe dominated by thesecondary modes, andmay cause primary mode amplification. Computational results of pressureand energy density fields will be presentedwhich provideinsight to optimalerror sensor placement for the two aforementionedcontrol methods. 2:20 2pSA4.Active controlof structuralvolume velocity using shaped PVDF sensors.Alain Berry (G.A.U.S.,D6pt. de g6nie m6canique,Univ. de Sherbrooke, Sherbrooke, PQ J1K 2R1, Canada) In low frequency,the sound power radiated from planar structures is simplyrelated to thenet structural volume velocity. A cost functionbased on thevolume velocity in activecontrol of structuralradiation has the advantage of keepingthe control simple (one errorsensor). The implementation of volume velocity error sensors in feedforwardcontrol of flexuralbeams and plates using shaped PVDF filmsis presented.For a beam,a singleextended strip of prescribedshape is needed,while in thecase of a panel,a numberof shapedstrips related to the numberof flexuralmodes contributing to the volumevelocity is required.The sensorobtained is independentof thetype and frequency of excitation.A procedurefor derivingthe appropriatesensor shape, based on analyticalor experimentalmodes, is discussed.The experimentalimplementation of volumevelocity sensors is addressedand resultsof active controlusing piezoceramic (PZT) actuatorsate presentedin thecase of a simplysupported beam, and simply supported or clamped panels.The strategyof minimizingthe volumevelocity is shownto providesignificant acoustic attenuation for structuralfree-field radiationor transmissionproblems. 2:45-3:00 Break 3259 J. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128th Meeting:Acoustical Society of America 3259 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp ContributedPapers 3:00 difficultto implementsuch complete control in practice.A preliminary experimentthat substantiatesthe conceptis described.Extension of this 2pSA5.Active control in three-dimensionalenclosures using multiple methodof noisecontrol to three-dimensionalcases is also brieflydis- secondarysources and error sensors. Scott D. Sommerfeldtand John cussed. W. Parkins (Appl. Res.Lab. and GraduateProgram in Acoustics,Penn StateUniv., P.O.Box 30, StateCollege, PA 16804) 3:45 The useof multiplesecondary sources and multipleerror sensorscan significantlyimprove global attenuationwhether one employsa control 2pSA8. One-dimensionalsound field control by sound pressureand methodbased on the squaredpressure or energydensity. A singlesource energy-densitysensor. J. WarnerSoditus and Jiri Tichy (Graduate positionedclose to a pressurenode will be inefficientat excitingthe cor- Programin Acoustics,Penn State Univ., P.O. Box 30, State College,PA respondingmode, therefore the secondarymodes will dominatethe pres- 16804) surefield, and attenuationis unlikely at the relatedfrequency. Increasing the numberof secondarysources improves the probabilitythat at leastone The use of an energy densityerror quantity for adaptivefiltered-x sourcewill not lie closeto a pressurenode, thereby mitigating this prob- active noisecontrol has been demonstratedto provideadvantages over lem. Problemsalso arisewhen error sensorsare close to nodes.Adding pressuresquared control in a one-dimensionalexperiment IS. D. Sommer- multipleerror sensors increases the probability that the sensors will be able feldt and P. J. Nashif, "An Adaptive Filtered-X Algorithm for Energy- to observethe dominant modes,which will yield improved attenuation. BasedActive Control,"J. Acoust.Soc. Am. 96, 300-306 (1994)]. The Using a greaternumber of error sensorsthan secondarysources will yield performanceof energy-density-basedcontrol was furtherexplored in com- a determinedcontrol system,with a unique optimal solution.If more parisonto pressure-squaredcontrol. By using two small microphones,the sourcesare used than sensors,an underdeterminedcontrol system will pressureand energy-densitysensor was moved throughregions of the result which can be uniquelysolved by adding more constraintsto the upstreamand downstreamof the secondarysource in a one-dimensional system,such as minimumeffort. The performanceof the energydensity low-frequencyharmonic sound field. Extensivedata were collectedfor versussquared pressure control methods are comparedas theyrelate to the various sensorlocations to demonstratethat the pressure-basedcontrol useof multiplesecondary sources and multipleerror sensors. stronglydepends on sensorlocation, while the energy-density-basedcon- trol is moresensor location-independent. 3:15 4:00 2pSA6. A structural-based acoustic intensity sensor. James P. Carnealand Gary P. Gibbs (Vib. andAcoust. Labs., Dept. of Mech.Eng., 2pSA9. Optimization of multiple piezoelectricactuator locationsfor VirginiaPolytech. Inst. and StateUniv., Blacksburg,VA 24061) active control of sound radiation from plates with arbitrary boundaryconditions. Tad Songand ChrisR. Fuller (Vib. andAcoust. A structural-basedacoustic intensity (SBAI) sensorhas been developed Labs., Dept. of Mech. Eng., Virginia Polytech.Inst. and State Univ., for low-frequencyapplications. The sensoris comprisedof a structural Blacksburg,VA 24061) mountedaccelerometer and pressuresensor. Local acousticintensity is calculatedby the time averageof the productof the velocityand pressure Active controlof soundradiation from plateswith arbitraryboundary measurements.The ability to usea structural-mountedpressure sensor was conditionsis studiedin this paper.An optimizationprocedure for the lo- confirmedwhen the phasebetween a nearfield andstructural-based pres- cationsof piezoelectricactuators is developed.The objectivefunction in suresensor was determined to be lessthan 5 degup to approximately1500 theoptimization is chosenas the sound power radiated from the plates. The Hz. Verificationof the SBAI sensorproceeded as follows.The structural- influenceof thechanges in thesupport conditions on theeigenproperties of basedacoustic intensity sensor output was shown to be proportionalto the the plateis evaluated.The numericalresults show that the controlperfor- output of a calibratedtwo microphoneintensity sensor from a piston mancewith respectto a boundarycondition change is dependentupon the source.Active control of the piston sourceusing the SBAI as an error excitationfrequency for the casewhere actuators are optimizedfor a cer- sensorshowed global reductionof radiatedacoustic power of approxi- tainboundary condition. However for thecase of simplysupported bound- mately15 dB for severalharmonic excitation frequencies. Active control arycondition, it is observedthat a changein thetranslational stiffness will of a complexstructure (plate) at variousfrequencies displayed mixed re- resultin degradedcontrol performance only when the translationalstiff- sults.For the (3,2) resonanceand a positionof (x/Lx=0.85, y/Ly =0.78), nessis significantlyless than infinite (i.e., simplysupported). [Work sup- globalreduction of radiatedacoustic power of approximately9 dB was portedby ONR.] achieved.However, other tests did not showthis type of reductionprima- rily due to the SBAI sensoracting as a local intensityestimator. It is evidentthat when applied to a complexstructure, the point(or points)at 4:15 which the intensitymeasurement is takenmust be chosencarefully to 2pSA10. Experimentson active control of wave propagationin obtaina globalestimate of the far field radiation. fluid-filled elasticcylindrical shells. BertrandJ. Brtvart and Chris R. Fuller (Vib. andAcoust. Labs., Dept. of Mech.Eng., Virginia Polytech. 3:30 Inst. and StateUniv., Blacksburg,VA 24061-0238) 2pSA7. Active sound extraction for noise control. Sameer I. Experimental results of studieson active vibration control in fluid- Madanshetty(Aerosp. and Mech. Eng., Boston Univ., 110 Cummington filled piping systemsarc presented.Reductions o[ the total power flow, i.e., St., Boston,MA02215) and Boa-TehChu (YaleUniversity, New Haven thepower flow in the shellwall andthe power flow in thefluid field,have CT 06520) beenachieved by meansof externalradial forces applied to thestructure. Axisymmetricwave propagation was first considered, using PVDF cables A methodof controllingthe noiselevel in ductflows is described.The bothas actuatorsand sensors. The shellradial displacement beyond the methodis basedon the principleof energyextraction by activesource(s), controldiscontinuity was reduced by 7 to 20 dB in a largefrequency range. ratherthan by wave cancellationas in "antisound."As suchthe methodof In addition,the internal pressure field was globally attenuated by theex- energyextraction is robust;it doesnot need the delicate signal processing, ternalforces. Considering a point force disturbance at low frequencies, perfectphase, and amplitude matching, crucial to soundcancellation. Two attenuationsof the shellmotion associated with higher-ordermodes (n usefulmodes of controlare discussed, one for quietinglow frequencies =1,2) havebeen achieved, by meansof shapedPVDF films as error sen- andthe othereffective for higherfrequencies. The possibilityof perfect sorsand point forces as structuralcontrol inputs. [Work supported by "noisetrapping" in a finiteregion is alsoconsidered, even though it is ONR.] 3260 d.Acoust. Soc. Am., Vol. 96, No.5, Pt.2, November1994 128thMeeting: Acoustical Society of America 3260 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 4:30 sensoriactuator.The transientresponse of the systemwas suppressed throughdirect-rate feedback control, and adaptive feedforward control was 2pSAII. The applicationof a biologicallyinspired controller to utilizedto minimizethe responseto a harmonicinput disturbance. A time- controlsound transm'ssion. JamesP. Cameal and Chris R. Fuller (Vib. averagedgradient descent algorithm was implementedto adapta finite andAconst. Labs., Dept. of Mech.Eng., Virginia Polytech. lnsl. and State impulseresponse filter in thefeedforward control approach. Experimental Univ.,Blacksburg, VA 24061) results demonstrate that rate-feedback control can be utilized to enhance A biologicallyinspired control approach for reducingsound transmis- theIransient adaplation of Ihe feedforwardcontrol algorithm. Furthermore, sionthrough a distributedelastic syslem has been theoretically and experi- thesensoriactuator provides a convenienlmethod of performingboth sens- mentallyverified for narrow-bandexcitation. The controlparadigm ap- ing andactuation simultaneously in feedbackand feedforward control of proximatesnatural biological systems for initiatingmovement, in thata adaptivestructures. low numberof signalsarc sentfrom an advanced,centralized controller 5:00 (analogousto thebrain) and are then distributed by localrules and actions 2pSAI3. Determinationof effectivesecondary source locations for to multipleactuators (analogous to musclefiber). A locallearning role that activenoise control. JibeYang (AutomatedAnalysis Corp., 2805 S. wasdeveloped from linear quadratic optimal control theory and solved a Industrial,Ste. 100, Ann Arbor, MI 48104}and DavidK. Holger (Iowa priori was implemented.The investigationconsidered a plateexcited by StateUniversity, Ames, IA 50011} normalplane wave, obliqueplane wave, and reverberantacoustic fields. Radiatedsound power was the definedcost function and thereforeused as A numericalmethod for determiningeffective secondary source loca- Ihc controllererror signal. Four control inputs in the form of piezoeleclric tionsfor activecontrol of interiorsound fields has been investigated. The actuatorswere mounledon the plate in a two-by-two array. Resultsindi- methoduses intermediate results from an indirectboundary element simu- cateIhat increasesin transmissionloss of approximately18 dB are attain- lation of a soundfield to determineeffective boundary locations for sec- able for off-resonaneeexcitation. In general,comparisons of theoretical ondarysources. In theindirect boundary element method (IBEM), anin- andexperimental data show good agreement. This investigationhas dem- teriorsound field is simulatedby replacingthe physicalboundaries with a onstratedthat the biologicalcontrol approach has the potentialto control fictitioussource distribution that is determinedfrom the geometry,the multimodalresponse in distributedelastic systems using an arrayof many propertiesof thephysical boundaries, and the primary source location(s). actuatorswith a reducedorder main controller.Thus significant reductions Locationsof high fictitioussource strength, as determinedby the IBEM, in controlsystem computational complexity have been realized by this are foundto be particularlyeffective locations for secondarysources that approach.[Work supported by NASALangley.] arecomponents in threedimensional active noise control systems. Numeri- cal resultsfor simplegeometries are in agreementwith previousexperi- 4:45 mentalresults [Elliott et el., J. SoundVib. 117, 35-58 (1987)],and nu- mericalpredictions of activenoise control using the proposedmethod for 2pSAI2. Experimental results from hybrid control with a locatingsecondary sources resulted in soundpressure level reductionsof sensoriactuator.Robert L. Clark andJeffrey S. Vipperman (Dept.of Mech. Eng. and Mater.Sci., Duke Univ., Durham,NC 27708-0300) morethan 20 dB in reverb•rantand semi-reverberant spaces. The results obtainedsuggest that the method has significant potentia. I for efficiently Bothtransient and persistentdisturbance rejection were demonstrated locatingeffective secondary sources for a varietyof activenoise control experimentallyon a cantileveredbeam configured with a piezoelectric applications. TUESDAY AFTERNOON, 29 NOVEMBER 1994 BALLROOM A, 1:30 TO 4:30 P.M. Session2pSP SpeechCommunication and EngineeringAcoustics: Microphone Arrays: Designand AnalysisII JamesL. Flanagan,Cochair CAIPCenter, Busch Campus, Rutgers University, Core Building 706, Piscataway, New Jersey 08855-1390 HarveyF.Silverman, Cochair Laboratoryfor EngineeringMan/Machine Systems, School of Engineering,Brown University, Providence, Rhode Island 02912 OiguangLin, Cochair CAIP Center,Rutgers University, Core Building, Frelinghuysen Road, Piscataway, New Jersey 08855-1390 ContributedPapers 1:30 benefitsfor speechcommunication. Various criteria for measuringthe per- formanceof a microphonearray are described.A flexible,experimental 2pSPl. Microphonearrays for reducingreverberation and noisein microphonearray intended for researchin speechcommunications isunder speechcommun'cation. James G. Ryan (Inst.for MicrostructuralSet., construction and will be described. Natl. Res.Council, Ottawa, ON K1A 0R6, Canada) 1:45 Microphonepickup of soundin typicalrooms is impairedby thecom- 2pSP2.Stable dereverberation using microphone arrays for speaker binedeffects of reverberationand noise. This degradesspeech intelligibil- verification. A.C. Surendranand J. L. Flanagan (Ctr. for Comput.Aids ityand quality particularly in applicationswhere the microphone islocated for Indusl.Productivity, P.O. Box 1390,Piscataway, NJ 08855-1390) far awayfrom the talker. Recent advances in microphonearray technology suggesta potentialsolution to suchproblems. This papergives an over- The impulseresponse of a reverberantenvironment, in general,is a view of currentmicrophone array techniques and discusses the potential nonminimumphase and cannot be inverted.But an exactinverse of the 3261 J. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3261 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp environmentcan he obtainedby modelingthe room as a multipleinput- are particularlyuseful when the noiseenvironment disturbs the ability to output(MINT) system[M. Miyoshiand Y. KanedaICASSP (1986)]. In communicatewithout error, such as in publicand cellulartelephony, air- this report,this modelis appliedto a microphonearray and is usedas a craftcommunications, etc. These differential microphones work bestwhen front-endprocessor for a speakerverification system. The G matrix is they are placedwithin 1 cm from the lips of the talkerwhere the sound invertedusing row action projection (RAP), an iterativeapproach to solv- field hasa largegradient. For a plane-wavesound field thesensitivity rises ing a systemof linearequations. Starting from an initial guess, the solution proportionalto to n, where n is theorder of thedifference. Users of differ- is repeatedlyprojected onto each hyperplane of the equationsystem until ential microphonesdo not always correctlyposition the sensorat the it converges.The methodis stable,robust to noise,and converges to the properdistance from the mouthand thereforethe sensitivityof the micro- pseudo-inversesolution. In computer-simulatedexperiments, the signal-to- phonemay alsorise proportional to ton especiallyat highfrequencies. A reverberant-noiseratio is found to improve with the numberof micro- method is describedof correctingfor this high-frequencygain without phonesin the array.A speakerverification system using the array is evalu- significantlydegrading the noisecanceling properties of first- and second- atedat varioussignal-to-competing-noise ratios (SCNR). Results suggest order differential microphones. that verificationperformance can be substantiallyelevated in adverse acoustic environments. 2:45 2:00 2pSP6.A newadaptive differential microphone array. Gary W. Elko andAnh-Tho Nguyen Pong (Acoust.Res. Dept., AT&T Bell Labs.,600 2pSP3. Binaural arrays for hearing enhancement. Michael V. MountainAve., Murray Hill, NJ 07974) Scanlonand Stephen M. Tenney (ArmyRes. Lab., AMSRL-SS-SH, 2800 An adaptivedifferential microphone has beenimplemented by com- PowderMill Rd.,Adelphi, MD 20783-1197) bining two omnidirectionalelements to form back-to-backcardioid direc- Two hearingaugmentation devices developed at the Army Research tionalmicrophones. By combiningthe weightedsubtraction of thesetwo Laboratorycan enhancenormal listening abilities and restorehearing de- outputslany first-order array can be realized.If certainsimple constraints gradedby encapsulatingheadgear. Surrounding sounds are localizedwith are placedon the combinationweighting, the null locationcan be con- a head-mountedbinaural pinna attachmentthat recreatesthe head-related strainedto definedangular regions. Three algorithms that control the con- transfer function associatedwith the normal listening. The user's brain strainedadaptation are presentedand discussedfor the array:the LMS interpretsthe recreatedstereo signals that enter the ear canalsthrough algorithm,Newton's algorithm,and a time-varyingleast-squares Wiener intra-auralspeakers, giving excellent restoration of omnidirectionalhear- filter.A real-timeimplementation utilizing an AT&T DSP32Cdigital signal ing. A hand-held,ultra-directional array extends the user'slistening range. processoris alsodescribed. The useof delayand sum beamforming in thearray assures maximum directivityin the pointingdirection. The binaurallong-range hearing de- 3:00-3:15 Break vice hastwo linearendfire arrays of eightcardioid microphones each. The slightlyoffset directivity patterns of the two arrayscreate stereo outputs, so 3:15 that the usercan interpretdifferences in amplitude,phase, time-of-arrival, and frequencycontent of soundsin the forwardarea. These devices pro- 2pSP7. An adaptive subband differential microphone. Juergen vide auralprotection and an intra-auralinput for communications,without Cezanneand Anh-Tho NguyenPong (Acoust.Res. Dept., AT&T Bell removing the user from his acousticenvironment. Both devices can be Labs., 600 MountainAve., Murray Hill, NJ 07974) monitoredremotely, and are ideallysuited for detectingspeech, personnel, equipment,or vehiclesduring military or law enforcementmissions. Per- In a previoustalk, "A new adaptivedifferential microphone array" by formartecmeasurements of variousarray configurations will be shown. Elkoand Pong, a differentialmicrophone has been introduced that adapts its directivitypattern to the particularacoustic environment to providefor a goodsignal-to-noise ratio. There, the selected pattern remains more or 2:15 lessconstant with respectto frequency.In this talk an approachis de- 2pSP4. A multisensorconnectivist model for the preprocessingof the scribedthat containsone more degreeof freedom.The spectrumof the speechsignals. TurkerKuyel and Elmer L. Hixson (Dept.of Elec.Eng., signalsis partitionedin uniformsubbands and different directivity patterns Univ. of Texas at Austin, Austin, TX 78712) are adaptivelychosen in eachsubband. This allowsto cancelmultiple noisesources with nonoverlappingspectra. An LMS-basedalgorithm will Due to the inherentredundancy of the speechdata, the designof a be derivedwith focuson a low computationalload and a shortdelay for the redundancyreducing speech preprocessor is very important.Preprocessor desiredsignal. Consequences on the speedof adaptationare discussed. designis alsovery importantbecause it can greatlyreduce the computa- Further,experimental results of a firstimplementation with 33 subbandson tional load on the later stagesof speechprocessing. A speciallaboratory a PC-basedDSP32C board will be presented.The measurementsverify the orientedmethod in speechdata acquisition, which is callednear-field spec- abilityof the algorithmto cancelmultiple noise sources with disjoint tral wave numberestimation is implemented.In this methodmultiple mi- spectrawithout distorting the desiredsignal. crophonesare used. The goalis to incorporateair flow velocityinto speech feature vector. This extra feature is used in addition to the short time 3:30 cepstmmof the sounddata to makethe final speechvectors. The speech vectorsare thenquantized into a determinednumber of categoriesusing a 2pSP8.Adaptive enhancement of microphonearray signals. Carsten self-organizingneural network. These quantizedand extendedvectors are Sydow (Inst. for Electroacoust.,Tech. Univ. of Darmstadt,Merckstr. 25, thenused for the modelingof higherspeech constructs such as phonemes D-64283 Darmstadt,Germany) andwords. The preprocessingscheme reduced the computational complex- ity considerablyat the expenseof slight reductionof the recognitionac- The signal-to-noiseratio of a speechsignal picked up by a microphone curacy. array can be improvedby adaptivepost processing.Enhancement tech- niquesknown from single microphone or dualmicrophone signal process- ing, like noisecanceling and spectralsubtraction can be extendedto a 2:30 multimicrophonearray system. The noisecanceling technique and derived 2pSP5. Position-tolerant differential microphones for noisy structurestry to modelthe roomimpulse response by an adaptivetrans- environments. JamesE. West, G. W. Elko, D. R. Morgan,and R. A. versalfilter. Thus the performanceof thesealgorithms is limitedby the Kubli (Acoust.Res. Dept., AT&T Bell Labs., 600 Mountain Ave., Murray ratioof filterlength to reverberationtime and by thecapability to trackthe Hill, NJ 07974) nonstationaryimpulse response. Reduction of thenoise of approximately8 dB canbe achievedwith acceptablefilter lengthin a stationaryenviron- Directionalmicrophones are best noted for theirnoise reduction prop- ment,but precautionsmust be takento avoid cancelingof the desired ertiesin communicationsystems. Close-talking differential microphones speechsignal. The spectralsubtraction met, •d yieldshigher improvements 3262 J. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3262 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp in signal-to-noiseratio up to 12 dB, but dueto falseestimation of magni- properselection of thesepre-filters is often problematic.The proposed tudeshort time spectrathe processedspeech signal contains distortion algorithmadapts the filtersduring an initial trainingsession to directly knownas "musicaltones." Different structures for adaptivepost process- minimizethe numberof locationestimation errors. The only information ingof microphonearray signals based on bothenhancement techniques are providedis the signalDOA, no explicitknowledge of the signalor noise presentedand discussed.Their performancein stationaryand nonstation- spectraare required.It is assumedhowever that the overallsignal/noise ary environmentsis characterizedby meansof improvementof thesignal- statisticsare long term stationaryover the trainingand subsequenttesting. to-noiseratio and subjectivespeech quality. Examplesof both linear and nonlinearfilter designare presentedfor a talker location identification task. 3:45 4:15 2pSP9.Crosscoupling effects on large widebandarrays. RichardK. Johnson(Siemens Meal. Systems, 22010 SE 51 St., Issaquah,WA 98027) 2pSPII. A model for the holographicreconstruction of soundfields disturbedwith temperaturegradients. Martin Guti6rrezV. (Inst.of The effectsof crosscouplingon array performancecan be well de- Acoust., Univ. Austral de Chile, Casilla 1130, Valdivia, Chile) and scribedby spatiotemporalor spatiofrequencycorrelation matrices. The JorgeP. ArenasB. (Inst. of Acoust.,Univ. Australde Chile, Valdivia, dataacquisition and analysisrequired for this approach,however, are very Chile) demandingtasks for largewideband arrays. The mostimportant effects of crosscouplingwithin an arrayare latentin singleelement beam patterns Holographictechniques are used to detect noise sourcesin a wide which are relativelysimple to measure.This paperdescribes the use of rangeof devices.Some of thesetechniques are commonly employed in the thesesingle element beam patterns to predictarray performanceand to reconstructionof soundfields produced by automobileor motorcycleen- establishcrosscoupling requirements. gines.These sound fields are characterizedby havingseveral, rather than single,temperatures; in fact,temperature gradients are frequently found in regionsnear the engine. These gradients produce changes in everypoint of 4:00 thesound wave velocity. The mathematicalmodel presented in thispaper 2pSP10.Minimum error soundsource localization. D. Rainton (ATR wasdesigned to minimizethe effect of assuminga constantsound velocity Human InformationProcessing Res. Labs., 2-2 Hikaridai, Seika-cho, in the entirespace in reconstructionof the soundfield. It is basedon the Soraku-gun,Kyoto 619-02, Japan) spacetransformation of sound field (STSF) technique [Held, J6rgen, B&K Tech.Rev. 1, 1-50 (1989)],which uses a microphonearray to measure A novelapproach to the problemof computingthe directionof arrival pressureor determinethe principalcomponent of crossspectra over a (DOA) of a soundsource using a two-elementmicrophone array is pre- hologramplane. The modelscans the soundfield in two planes.The first sented.Typically, the DOA is computedby peakpicking from the resulting planeis usedas an STSFinitial condition (hologram plane), and the second cross-correlationfunction. In orderto improvesuch estimates it is usually planeis consideredthe boundarycondition to Rayleighintegral's propa- desirableto pre-filterthe signalsprior to crosscorrelation. However, gation. TUESDAY AFTERNOON, 29 NOVEMBER 1994 BALLROOM B, 1:00 TO 5:00 P.M. Session2pUW Underwater Acoustics:Moderate-to-High Frequency Bottom Interacting AcousticsII Kevin L. Williams, Chair AppliedPhysics Laboratory, University of Washington,1013 NE 40th Street,Seattle, Washington 98105-6698 Chair's Introduction--l:00 Invited Papers 1:05 2pUWl. Propagationin range-dependentporo-elastic media. MichaelD. Collins (Naval Res. Lab., Washington,DC 20375), W. A. Kuperman(Scripps Inst. of Oceanogr.,La Jolla,CA 92093),and WilliamL. Slagmann(Rensselaer Polytech. Inst., Troy, NY 12180) Biot'stheory of poro-elasticityis derivedfor heterogeneousmedia and reduced to a systemof threecoupled equations. Previous formulationsof this probleminclude a redundantfourth equation. The reducedsystem factors into incomingand outgoingwave equationsand may thereforebe solvedwith the parabolicequation (PE) method,which is usefulfor range-dependentproblems. The operatorsquare root is approximatedusing rational-linear functions that were originallydesigned for the elasticPE and provide accuracyand stability. An initialcondition for theporo-elastic PE is obtainedwith theself-starter, which has been generalized to handle compressionaland shearsources in poro-elasticmedia. Qualitativetests involving the propagationand reflectionof slow and fast compressionalwave beams and •hear wave bearna demonstratethat the poro-ela•ti½ PE handle• all wave type•. A solution ba•ed on the wave-numberspectrum has been developedto test the poro-elasticPE quantitatively.The PE and spectralsolutions are nearly identicalfor problems involving a water column overlying a poro-elastic sediment. A nonlinear relationship involving the coefficients of thewave equation and the Blot moduli has been worked out so that the natural parameters (i.e., porosity, density, wave speeds, and attenuations)may be usedas inputsto propagationmodels. 3263 J. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November 1994 128th Meeting:Acoustical Society of America 3263 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 1:25 2pUW2.A newhigh-frequency ocean bottom backscattering model, NicholasP. Chotiros and Frank A. Boyle (Appl.Res. Labs., Univ. of Texasat Austin, P.O. Box 8029, Austin,TX 78713-8029) A newmodel of acousticbackscatter from the ocean bottom is presented.Based on the analysis of existing data, three main physicalmechanisms have been identified. These are gas bubbles, sediment grains, and interface roughness. Gas bubbles are particu• larlyprevalent in shallowwater sediments. A single-scatter approximation is used to modelthe bubble scattering. Scattering from sedimentgrains is a multiple-scatterproblem which is still underinvestigation, but an empiricalrelationship is available.Scattering frominterface roughness is modeledin termsof a Kirchhoff-Helmholtzscattering integral. The totalbackscattering strength is an incoherentsum of the threecontributions. It is foundthat the interfaceroughness is dominantnear normal incidence. The othertwo mechanismstend to dominantat shallowgrazing angles. [Work supported by Naval Research Laboratory, Stennis Space Center under theMCM TacticalEnvironmental Data System (MTEDS) project.] 1:45 2pUW3.High-frequency acoustic bottom reverberation. S. Stanic,E. Kennedy(Naval Res. Lab. Code 7174, Stennis Space Center,MS 39529),and R. Goodman(AppL Res. Lab., Penn State Univ., State College, PA 16804) A seriesof high-frequencybottom backscattering experiments were conducted off thecoast of PanamaCity, Florida. Reverberation resultswill bepresented asa functionof frequency(20 to 180kHz) and grazing angle (5ø-30ø). Geoacoustic parameters taken during theexperiments will be usedas inputsto an existingseafloor backscattering model initially developed by D. R. Jacksonet al. [J. Acoust.Soc. Am. 79, 1410-1422(1986)], and modified by A. Lyonset al. [J. Acoust.Soc. Am. 95, 2441-2451(1994)]. The experimentaldata will then be comparedto thesemodel simulations. 2:05 2pUW4.Modeling the sonar backscatter by objectsburied in veryshallow water. RaymondLim (Code130B, Coastal Systems Station,Panama City, FL 32407-7001) Conventionalsonar systems for bottom searching underwater coastal environments have limited long-range classification capa- bilities.This is especiallytrue when objects searched for aresignificantly buried so thatimaging is difficult.To investigatethe feasibilityof nonimagingmethods of classification(e.g., based on isolatingresonances in the echo from the desired object), models thatfaithfully predict the acoustic response of known objects in various states of burialare required. Because the response of the object canbe strongly modified by thestructure of itslocal environment, anappropriate model must account for effects due to propagating theacoustic field to and from the object, the scattering itself, and the interaction of the object with its local environment. The present talkwill discusshow these issues can be handledin anexact fashion via a transition-matrixformulation both for fullyburied and partiallyburied objects. In eithercase, the solution involves identifying a suitable set of globalbasis functions. [Work supported by ONR andthe CSS IR program.] ContributedPapers 2:25 2:40 2pUW5. Acoustic form function for porous solid spheres: 2pUW6. Moderate frequencyscattering from objectsin an elastic Comparison between theory and experiments. Kerry W. bottomwith rough interfaces. Jaiyong Lee and Henrik Schmidt (Dept. Commander,Raymond Lira (CoastalSystems Station, Panama City, FL of OceanEng., MIT, Cambridge,MA 02139) 32407-7001), TheodoreW. L. Huskey,Steven R. Baker (Naval PostgraduateSchool, Monterey, CA 93943-5000),and StevenG. Kargl (Univ.of Washington,Seattle, WA 98105) Thediffuse reverberation from small scale bottom roughness severely affectsthe spatial coherence of the scatteredfield from near-bottomburied An underwateracoustic scattering experiment was performed on three objects.To investigate this phenomenon theoretically, a numerical model is poroussolid spheres of varyinggrain size to determinetheir acoustic form beingdeveloped for moderatefrequency scattering from an elasticinclu- functions.The sphereswere constructed from bonded glass beads, sized to sionin a stratified,rough bottom. The model combines theories for object yieldpermeabilities in therange of fineto mediumgrained sand. Measure- scatteringand small-scalerough interface scattering. For the numerical mentsof requiredmaterial and lattice parameterswere determinedon implementation,a global approach is introduced,which combinesthree analogouscylindrical samples, including a measurementof the dry lattice differentmethods into a consistenthybrid scheme. Boundary elements are moduliper the methoddeaeribed by Garrett[õ. L. Garrett,J. Acoust.•oc. used to computethe effects due to an elastic inclusion [P. Gerstoft and H. Am. 88, 210-221 (1990)]. Quantitativeagreement between the acoustic Schmidt,J. Acoust.Soc. Am. 89, 1629-1642 (1991)],wave-number inte- measurementsand predictions from a theoreticalBiot modelIS. G Kargl grationprovides numerical Green's function for thehorizontally stratified and R. Lim, J. Acoust.Soc. Am. 94, 1527-1550 (1993)] was foundbut only at thelow-frequency end (<20 kHz) of the measurementsand for the medium,and finally the rough interface scattering is handled using a self- smallergrained spheres. Although the measured and predicted form func- consistentperturbational method[W. A. Kuperman andH. ;Schmidt, J. tionswere still qualitatively similar at higherfrequencies, deviations due to Acoust.Soc. Am. 86, 1511-1522 (1989)]: Compared toearlier implemen- inhomogeneitiesin the porousspheres became evident. For each discrete tations,the efficiency of theboundary element component of themodel has frequencymeasurement, the spheres were rotated 360 degand variations in beensignificantly improved by introducinga new analytical integration the backscatteringstrength noted. For valuesof ka wherelittle variation approachto thecomputation of the influence matrices. The modeling ap- with sphereorientation was obtained, there was good agreement with the proachwill be describedand its applicationto realisticsonar scenarios will theoretical model. bedemonstrated. [Work supported byONR.] 3264 J. Acoust. Soc. Am., Vol. 96, No. 5, Pt. 2, November 1994 128thMeeting: Acoustical Society of America 3264 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp •:55 2pUW7. Moderate frequency acoustic penetration of a sandy 2pUW10. On measuringsediment/Biot properties in shallow water shallow water sediment. Nicholas P. Chotiros (Appl. Rcs. Labs., at moderate to high frequencies. Ahmed Abawi, W. S. Hodgkiss,W. U.niversity ofTexas at Austin, P.O. Box 8029, Austin, T• 78713-8029), A. Kuperman(Scripps Inst. of Oceanour.,Univ. of CaliforniaSan Diego, Age Kristensen,and EnzoMichelozzi (SACLANT UnderseaRes. Ctr., La Jolla, CA 92093-0701}, and Michael D. Collins (Naval Res. Lab., 19026 LaSpezia,llaly) Washington,DC 20375} A broadbandline arrayis beingdesigned and constructed to studythe An experimentwas conductedto investigateacoustic penetration of a acousticsof shallowwater in the moderateto high-frequencyregime. The sandyshallow water sediment, in the band500 Hz to 2 kHz, in a siteoff 64-elementarray will consistof nestedapertures half-wavelength spaced at LaSpezia,Italy. Acoustic sensors were buried in the sediment,forming a 4, 8, and 16 kHz with a total bandwidthof 2-20 kHz. The intentionis to sparsethree-dimensional array, to measurethe sedimentpenetrating sig- nals.The soundsource was a sparker.The collectedsignals are processed studyboth the forwardand inverseproblem, the latterwith respeelto coherentlyto give directionand speedof the sedimentacoustic waves. sedimentproperties. The poroelastic parabolic equation [Collins et al., this Froma theoreticalpoint of view, the mediumis treatedas a poro-elastic meeting]is being used for simulations to (1) aidin thedesign of thearray, (2) studythe forwardproblem, and (3) investigatethe potentialobserv- solidgoverned by Biot'stheory of acousticpropagation. It is predictedto supporttwo acousticwaves. Comparisons are made betweentheory and ableswith respectto the inverseproblem. In particular,it is of great experiment.[Work supported by Officeof NavalResearch, Ocean Acous- interestas to whethereffects related to the Biot dcseriplionare observable tics Program,Code 11250A, underthe initiativefor basicresearch in the by measuringwaveguide propagation. The use of the parabolicequation physicsof moderateto highfrequency acoustics.] formulationwill allow for a consistentextension to range-dependenten- vironmentsin a futurestudy. [Work supported by ONR Code321OA.] 4:15 3:10-3:30 Break 2pU%VII. Hybrid methodsfor incorporatingdensity variations into the split-stepPE. David Yevick (Dept. of Elec. Eng., Oucen'sUniv., Kingston,Ontario K7L 3N6, Canada)and David1. Thomson (Defence Res. F_stab.Pacific, FMO Victoria, BC V0S lB0, Canada) 3:30 Densityvariations are easily analyzed in the contextof finitedifference 2pUW8. High-frequency acoustic penetration of ocean sediments. parabolicequation (PE) solversby discretizationof an appropriatediffer- NicholasP. Chotiros,Robert A. Altenburg (Appl.Res. Labs., University ential operator.In split-stepFourier solution algorithms, however, varia- of Texas at Austin, P.O. Box 8029, Austin, TX 78713-8029), and tionsin the densityp areinstead modeled by addingterms to the refractive StephenJ. Stanic (Naval Res. Lab., StennisSpace Center, MS index. Since theseextra termsdepend on derivativesof p, geoacoustic 39529-5004) densityprofiles must be smoothedappropriately to removeany stepdis- continuities.In this paper,a new hybridmethod is proposedfor treating Twoexperiments were conducted to investigateacoustic penetration of densityinhomogeneities in the split-slep PE. This approachinvolves split- oceansediments: one in a muddysite in the Baltic Seaand the otherin a ting the differentialoperator into density-independentand density- sandysite in the Gulf of Mexico.In both experiments,acoustic sensors dependentcomponents. While the formercomponent is propagatedusing wereplaced in the sedimentto measurethe acousticsignals. The signals the split-stepFourier technique, the influenceof densitychanges is com- areprocessed coherenfiy to givedirection and speed of theacoustic waves. putedthrough a finitedifference procedure. Such an algorithm is especially The datafrom the two sitesgive very differentresults. In the muddysite, attractiveas it may be transparentlyincorporated into the recentlypro- thesediment sound speed is veryclose to thatof thewater, the situation in posedhybrid split-step/finite-difference andsplit-step/Lanczos solvers [$. thesandy site is morecomplicated. The mediumis treatedas a poro-elastic Acoust.Soc. Am. 96, 396-405 (1994)].Both the hybridand the standard solidgoverned by Biot'stheory of acousticpropagation. For thesandy site, finite-differenceprocedures are applied to a shallow-watertest case involv- thetheory predicts two acousticwaves, one faster than the sound speed in ing jump discontinuitiesin boththe soundspeed and the densityand are water,and the otherslower. Comparisons are madebetween theory and foundto be in excellentagreement with referencesolutions. experiment.[Work supportedby Officeof Naval Research,under the CoastalBenthie Boundary Layer (CBBL) Special Research Program.] 4:30 2pUWI2, Finite d•fferencesimulations of propagationin a shallow water environment. John B. Schneider,Shira Lynn Brosehat,and 3:45 PatrickJ. Flynn (Schoolof Elec. Eng. and Cornput.Sei., Washington State Univ., Pullman,WA 99164-2752) 2pUW9. The effect of roughnesson acoustic penetration of the oceanbottom. lohn E. Moe andDarrell R. Jackson(Appl. Phys. Lab., The propagationof acousticenergy in a shallowwater environment is Univ.of Washington,1013 NE 40thSt., Seattle,WA 98195) studiedusing a two-dimensional,staggered-grid finite-difference model. Sucha modelallows one to view the propagationof energyin the time The acousticintensity penetrating a roughsurface is analyzedusing domainthroughout the regionof in•erest.Since fields are available"ev- Rayleigh-Riceperturbation theory. When the grazing angle of theincident erywhere,"the modelcan be usedto guidethe developmentof robust field is belowthe criticalangle in relationto the meansurface, only the schemes for the detection of scatterersin the water column or buried in the zero-ordercomponent of the transmittedfield is evanescent;the higher- sedimenl.In addition,it canbe usedto benchmarkapproximate models for ordercomponents conlain downward traveling waves. For an incident field acousticpropagation and scattering in shallowwater. This paper considers belowthe critical angle, first-order computations using parameters appro- the effectof differentphysical features on the possibleidentification of priateto a sandybottom show that the field below the rough surface can be scatterers.Such scattering mechanisms as top andbottom roughness and muchgreater than the correspondingfield below a fiat surface.These inhomogeneitiesin the water columnare considered.Monte Carlo simu- computationsare carried out usinga low-frequencycutoff for the bottom lationsare usedto gaugethe relativeeffects of thesefeatures. Frequencies relief spectrum.With regardto the accuracyof the calculation,both the on the orderof 7.5 kHz are consideredfor depthsup to 30 m. The imple- short-wavelengthportion of therelief profile that is retainedas well asthe mentation used here includes several enhancementsover traditional finite- long-wavelengthportion that is discardedare considered.It is shownthat differencemodels. For example,typical finite differencemodels approxi- the rms heightof the portionretained and the rms slopeof the portion matecontinuously varying material interfaces by an interfarethat appears discardedare sufficientlysmall to lendconfidence in the perturbationap- like a staircase--thematerial properties change only at discretelocation. proach.Further work is required,however, to unequivocallyestablish the For this researcha conformaltechnique is usedto modelmore accurately accuracyof themethod. [Work supported by ONR.] thecontinuous interface. [Work supported by ONR.] 3265 J. Acoust.Sec. Am., VoL 96, No. 5, Pt. 2, November1994 128th Meeting:Acoustical Society of America 3265 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 4:45 definedin theseterms has an inherentpropagation component. Analytical work hasbeen carried out for the propagationof Gaussianbeams in ho- 2pUW13. Optimum beam widths for senfloorscattering problems. mogeneousand heterogeneous media [for example,Cerveny er el., Geo- R. A. Stephen(Woods Hole Oceanogr.Inst., Woods Hole, MA 02543) phys.I. R. Astron.Soc. 70, 109-128 (1982)].For a givenpropagation Gaussianbeams are often usedfor the insonifyingfield in scattering distancethere is an optimalinitial beamwidth that will minimizethe width problemsfrom interfaces. They have the advantage of restrictingthe graz- of the beam alongthe whole path.Consequently for a given angieof ingangie content of theincident field while localizing the scattering region incidenceand a givenincident amplitude threshold, there will be a mini- on the interface.However a disadvantageis thatthe beamsspread signifi- mum surfacescattering area. Optimumbeamwidths can be definedand cantly.For oblique incidenc e, the width of thebeam can vary significantly theseshould be usedby all investigatorsin orderto standardizeresults. overthe regionof interactionon the interfaceand the scatteringproblem [Worksupported by Officeof NavalResearch.] WEDNESDAY MORNING, 30 NOVEMBER 1994 BRAZOS ROOM, 8:00 A.M. TO 12:05 P.M. Session 3aAA Architectural Acoustics: Case Studies in Architectural Acoustics J. ChristopherJaffe, Chair JaffeAcoustics, Inc., 114AWashington Street, Norwalk; Connecticut 06854 Chair's Introductions8:00 Invited Papers 8:05 3aAA1.Report on theCerritos Centre for thePerforming Arts. JerryGodden (Theatre Projects Consultants, 3 Apollo Studios, CharltonKings Rd., LondonNW5 2W, U.K.) Smalland mediumsized communities wanting a high qualityperforming arts space are facedwith reconcilingthe conflicting demandsthat differentarts forms make on the performancespace. The recentlycompleted Cerritos Centre for the PerformingArts in Californiais unusualin its designin that it utilizesmodem technology to providea spacefor the performingarts that can becomea 1896-seatconcert hall, a 1450-seatlyric theatre,a 900-seatdrama theatre, a 1934-arenatheatre, or a cabaretspace seating 1472. The auditoriumis transformedincluding its seating,its sightlines,and its acousticsby the use of movableseating towers. The design demonstrateshow a smalltown can affordto build and operatea facility in scalewith its capabilitiesand aspirationsand may well proveto be a key pointin the conceptof multipurpose spaces of the future. 8:35 3aAA2. Problemsassociated with the renovation of existing music practice facilities. David P. Walsh (Walsh,Norris & Associates,Inc., 25 Drumm St., San Francisco,CA 94111) The acousticaldesign of musicpractice and rehearsalfacilities is alwaysan interestingand challengingtask. However,the challengesincrease significantly when the project is a renovationof existingfacilities rather than a newdesign. In renovationprojects, extensiveinvestigation and evaluationof the buildingstructure and constructionassemblies are requiredsince, in a greatnumber of ca•s, theoriginal drawings are no longeravailable. It is alsonot unusualfor undocumentedmodifications to havebeen completed to thestructure over the years.A workingknowledge of outdatedconstruction techniques and materials is typicallyrequired. This paper presentsa casestudy of therenovation of thepractice and rehearsal facilities for a universitymusic department originally constructed in 1956.The original wall andceiling systems did not provide satisfactory airborne sound isolation between practice rooms and major modificationswere begun less than a yearafter opening. These modifications improved the overalldegree of soundisolation between practicerooms somewhat, however, they were not completelysatisfactory. This paperdiscusses the currentmodifications, together with thecomplications inherent in workingon a buildingover 30-years-old for whichminimal information on theoriginal construction assemblies was available. 9:05 3aAA3. Sound isolation criteria for Cornell University Music Department. Timothy J. Foulkes and William J. Cavanaugh (CavanaughTocci Associates, Inc., 32717Boston Pcxst Rd., Sudbury,MA 01776) A detailedcase study in soundisolation crileria for a new musiceducation facility at a majoruniversity is presented.Part of the departmentis to be housedin an existing,hisstie buildingwith woodfloor structures. Part of thenew facility will be an addition(new construction). 9:35-9:50 Break 3266 d. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128thMeeting: Acoustical Society of Amedca 3266 Downloaded 27 Jun 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 9:50 10:35 3aAA4. Acoustic project of "Mexico Radio ABC" broadcasting 3aAA7. BACH, a new binaural room acousticalmeasure. Ant6nio rooms.Aria Maria Vald6s (Av. Popocatepetl 295-7, M6xico 03340 D.F., PedroO. Carvalho (ArchitectureTechnol. Res. Ctr., 331 ARCH, Univ. of Mexico)and MarioVizquez-Rafia (Organizaci6n Editorial Mcxicana, Florida,Gainesville, FL 32611-2004) GuillermoPrieto 7, Col. SanRafael, M6xico 06470 D.F., Mexico) This studyreports on acousticalfield measurementsmade in a major Designfor roomacoustic insulation, reverberation time, and homoge- surveyof 41 Catholicchurches in Portugalbuilt in the lastfourteen cen- neousdiffusion of acousticfield, resultsin high buildingbudgets for turies.Binaural measurements were takenin eachchurch using a dual- broadcastingand TV stations,theaters, etc., projected in Mexico.For this channelreal-time frequency analyzer to calculatethe coherencevalues reason,they are often constructedwithout an adequateacoustic design. betweenthe signalsat bothears in 1/3-octavefrequency bands. From the This paperpresents the acousticdesign applied to theconstruction of three coherencevalues a new binauralacoustical measure was developedand broadcastingstudios for "Mexico Radio ABC," consideringboth a low called BACH (BinauralAcoustical CoHerence). Manaural acousticalmea- cost projectand long life materialsfitted for the Mexico City's environ- surementswere alsotaken at severalsource/receiver locations using the ment,and takinginto accounta new nationaldraft standard.The project impulseresponse method. BACH was shownto be an orthogonalparam- wasplanned for noisysurroundings (sound pressure levels averaged of 78 eter in statisticaltests with nine other manauralacoustical measures (RT, dB,A-weighted). External noise comes mainly from traffic, nearby schools EDT, C80, D, TS, L, BR_RT,BR_L, and RASTI) andfifteen architectural andhelicopters; indoor noise comes from air conditionedand background parameters.Information was collected regarding the qualityof musicin officenoise. The original volume shape was a parallelepiped,which had to eachchurch. ANOVA testswere performed to examinethe significanceof be transformed to avoid undesirable reflections. The reverberation time the differencesamong the groupsof equalsubjective quality ratings. The chosenfor controlrooms was 0.35 s at 1000 I-Iz, and 0.22, 0.25, and 0.35 authorwanted to testthe hypothesis that this new binaural acoustical mea- s at 1000 I-Iz for broadcastingstudios; these values were achievedin surecan be usefulin estimatingthe generalsubjective quality of churches practice.Final costswere low, in comparisonwith a constructionwithout regardingmusic. A linearcorrelation coefficient near 0.7 was foundbe- previousacoustic design. tweenthe BACH and the subjective quality ratings that supported the stated hypothesis.This is exploratoryresearch and developments are being tested to improvethe model. [Work supported by JNICT/Ministryof Planning andUniv. of Porto,Portugal.] 10:05 3aAAS. Sound isolation of an audiometric test room. Arno S. 10:50 Bornmetand CharlesT. Moritz (Collaborationin Sci. andTechnol., Inc., 15835 Park Ten Place,Ste. 105, Houston,TX 77084-5131) 3aAA8. Field impact insulationclass (FIIC)--A casestudy. JohnJ. LoVcrdcand Gary Mange (WesternElectro-Acoust. Lab., 1711 Sixteenth Modificationswere required to reducesound levels in a formeroffice St., SantaMonica, CA 90404) so that the roomwould meetthe ambientnoise requirements for audio- metrictesting. Sound sources in the areaincluded people in neighboring Impact noisein buildingsconstitutes a potentiallyserious problem offices,transformers in a neighboringmechanical equipment room, venti- becauseof the shortduration, high intensitysounds involved [U.S. De- lationducts in the plenumabove the room,and air-conditioningvents. The partmentof Housing and Urban Development,Airborne, Impact, and transformerscreated harmonically related vibration tones in the concrete StructureBorne Noise, Chapter 7 (1967)]. Since1974, the Stateof Cali- floorslab and walls that radiated sound into the proposedaudiometric test forniahas tried to managethis problem by institutingthe California Noise room. Acousticalrecommendations consisted primarily of building a InsulationStandards, which require any multi-familydwelling to provide vibration-isolatedroom within the existingroom (includinga floating an impactinsulation class (llC) ratingof 50 basedon laboratorytests, or a floor)and acoustically treating the ventilation system. Initial measurements fieldimpact insulation class (FllC) ratingof 45 basedon field tests [Office revealedunexpectedly high sound levels that were the resultof unintended of Noise Control,California Noise InsulationStandards, 1-7 (1988)]. (erroneous)structural connections between the inner and outer room. Concernabout the acceptabilityof floor ceilingassemblies is increasing When theseconnections were cut, the roommet the noiserequirements. dueto increasedawareness of the problemand larger numbers of people movinginto apartments,condominiums and townhomes throughout Cali- fornia.Western Electro-Acoustic Laboratory (WEAL) hadthe opportunity 10:20 to witnessthe installationof floorceiling assemblies in an apartmentcom- plex in Bakersfield,California. Six differentassemblies were testedto 3aAA6. Seat-dip phenomenon. David Greenberg (Jaffe Holden determinehow the FIIC value changedwhen minor modificationswere ScarbroughAcoustics, Inc., 114A WashingtonSt., Not•valk,CT 06854) madeto the standardfloor ceiling assembly. WEAL will showthe results and CourtheyBurroughs (Appl. Res. Lab., State College, PA 16804) of the field-testedassemblies and compare the data with typicallaboratory results for similar constructions. The "seat-dipphenomenon" is socalled because an anomalousattenu- ation(dip) in thefrequency response of auditoriumsis foundto be caused by thepresence of rowsof seats.As soundfrom the stage grazes over seats, 11:05 it is subjectto broadattenuation of the low frequenciesfrom 75 to 300 I-Iz. 3aAA9. Effect of concave sound reflecting surfaces on speech This frequencydip can be as muchas 20 dB below the soundlevel without intelligibilityand the articulation index. SamiA. Khaiyat (Dept. of the presenceof seats.Experiments were performedwith a simple 1:10 Architecture,Texas A&M Univ., P.O.Box 2844, Bryan,TX 77805-2844) scalemodel of an auditoriumfloor. It is foundthat the dip is causedby a and LesterL. Bayer (TexasA&M Univ.,College Station, TX 77843) coincidenceof effectsrather than the single effect dominantin the litera- ture.The effectsare considered. (1) A standingwave betweenthe seatand Two different methods,the calculation of the articulation index (AI) sourcewith nulls relating to thequarter-wavelength distance, (2) half-wave andthe rapidspeech transmission index (RASTI) measurementusing the cancellationswhere reflected and/or diffracted waves interfere with the speechtransmission meter, were utilized to obtainthe speech intelligibility on-comingwave, and (3) thepropagation of the soundof interestat nearly in spaceswith concavesound reflecting surfaces. Many factorswere con- zerodegrees over the seats. It is shownthat the standing waves and sound sideredsuch as room size,size of curvature,position of the soundsource, pressurecancellations associated with eachsuccessive row of seatsoccur andbackground noise level. The basecases, spaces without curvatures, at frequenciesthat are very closeto eachother. The effectof frequency showedhighly correlated results indicating no significantdifferences be- spreadingof (1) and(2) arepresented. tween calculated AI and measured RASTI. With curvatures and the sound 3267 J. Acoust. Soc. Am., Vol. 96, No. 5, Pt. 2, November 1994 128th Meeting: Acoustical Society of America 3267 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp sourceat 4 fl. awayfrom the centerposition of the frontwall it wasfound mentswith simulated concert-hall sound fields using anechoic symphonic that the effect of room size is significantlydifferent between the two music presentedto subjectsby multiple loudspeakers."Equal ASW methodsunder the 2- and 16-ft. radiuscurvatures only; also,the back- curves"were determined for 1/1 octaveband filtered source signals with groundnoise level showedalmost the sameeffect on bothcalculated AI mid-frequenciesfrom 125 to 4000H_z. The ASW's for theupper four bands and PAST[. Under low backgroundnoise levels, spaces with curvatures arefound to be equalfor thesame IACC andSPL band values, indicating showedthat the effect of changein roomsiz• for bothmethods is identical. equalimportance of thosebands in determiningoverall ASW's. Combina- The centerlocation for the soundsource showed better speech intelligibil- tionsof GL's andIACCE3's (averageof IACC's in the 500, 1 and 2 kHz ity underall differenttesting conditions. Finally, a modificationfactor is bands)for wide-bandmusical source signals were determinedthat pro- developedand appliedto the calculatedAI so that reliableestimates of ducedthe sameASW's. The early soundwas comprisedof 2 to 11 early speechintelligibility in spaceswith curvaturesmay be obtained. "reflections"and judgments were madewith andwithout later reverbera- tion. It was found that both larger valuesof GL and smallervalues of 11:20 IACCE3 resultin largervalues of the subjectivelydetermined ASW's. It is shownthat GL and IACCE3 jointly are physicalmeasures of spatialim- 3aAAI0. Relationsbetween the apparent sourcewidth (ASW) of the pressionin a concerthall and that, combined,they coverthe frequency sound field in a concert hall and its sound pressure level at low rangefrom low to high frequencies. frequencies(GL), and its inter-aural cross correlation coefficient (IACC). ToshiyukiOkano, Takayuki Hidaka (TakenakaRes. and 11:35-12:05 Develop. Inst., 1-5, Ohtsuka,Inzai-machi, Inba-gnn, Chiba, Japan, 270-13),and Leo L. Beranek (975 MemorialDr., Ste.804, Cambridge, PANEL DISCUSSION: Weighing Cost VersusBenefit in Music Edu- MA 02138) cation and Performance Facilities The influenceof GL (amplifiergain the low-frequencyrange below Panel Moderator: J. ChristopherJaffe 355 Hz) and IACC on ASW was determinedby psychoacousticexperi- Panel Members:Timothy J. Foulkes,J. Godden,David P. Walsh WEDNESDAY MORNING, 30 NOVEMBER 1994 SABINE ROOM, 8:00 A.M. TO 12:15 P.M. Session 3aAO Acoustical Oceanographyand Animal Bioacoustics:Effects of Soundson Marine Mammals: Update and Discussion on the Need for Standards II Charles R. Greene, Jr., Chair GreeneridgeSciences, Inc., 4512 l•a Huerto, Santa Barbara, California 93110 Chair's Introduction--8:00 Invited Papers 8:05 3aAOl. Modular'ondetection interference on presentationof two amplitude-modulatedtones. WilliamF. Dolphin (Dept.of Biotaed.Eng., Boston Univ., Boston, MA 02215) Psychephysicalstudies have shown that the processing of modulationin onefrequency channel is interferedwith whena similar modulationpattern is presentin anotherfrequency channel. To testfor physiologicalcorrelates to thisphenomena a sinusoidally amplitude-modulated(SAM) probetone was presentedin the presenceof a simultaneouslygated, modulated, or unmodulated interferingtone while recording from the scalp of anesthetizedgerbils. Responses were recorded from the scalp, amplified, digitized, andaveraged. The amplitudeof theresponse was determined as the magnitudeof the Fouriertransform measured at the frequency correspondingto the probe .freed and re. Responsesin the presence of theinterfering tone were compared to responsesobtained to the SAM probetone alone. The shape of theinterference pattern was highly dependent on the modulation frequency of theinterfering tone. With somemodulation frequencies an increasein interferencerelative to controlresponses was observed at theprobe fmoa, while at othermodulation frequencies either no interference,or evenenhancement of the responsewas apparent. In contrast,at theprobe .re interferencepatterns were very similarfor all interferencetone modulation frequencies. 8:25 3aAO2.A changein spermwhale (Physeter rnaeroephalus) d'stribution correlated to seismicsurveys in the Gulf of Mexico. BruceR. Mate (HatfieldMarine Sci. Ctr., Oregon State Univ., Newport, OR 97365), KathleenM. Stafford(Oregon State University,Newport, OR 97365),and DonaldK. Ljungblad(Elk Mountain,WY 82324) From7 to 29 June1993, vessel surveys for sperm whales were conducted in the Gulf of Mexicooff theLouisiana coast. Ninety spermwhales were seen in water600 to 1400m deep.On four of thefirst five survey days, whales were found routinely in anarea 100km S.E. of theMississippi River before a seismicsurvey operation began (0.092 whales/kra). Within the seismic operations area, whaleabundance changed significantly to 0.038 whales/kin during the first two days and then to 0.0whales/kin for the following five days(p value<0.001). During the first two days of seismicactivity, whales were only seen around the periphery of theseismic area. Surveyeffort for the last 5 days(920 kin) and revealed only one group of fouranimals 61 km S.W. of theseismic survey area and also 56 kmN.E. from another active seismic survey. Although the observation of seismic survey activity was serendipitous, it was highly 3268 J. Acoust.Soc. Am., Vol. 96, No.5, Pt.2, November1994 128thMeeting: Acoustical Society of Amedca 3268 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp correlatedto numbersof spermwhales. This relationship deserves further investigation. If validated, additional efforts will be needed to identifyareas used by spermwhales and assure that the effects of simultaneousseismic surveys do notoverlap and prevent sperm whalesfrom usingimportant habitat. 8:45 3aAO3. Developingstandards for protectingmarine mammals from noise:Lessons from the developmentof standardsfor humans. Ann E. Bowles (Hubbs-SeaWorld Res. Inst., 2595 IngrahamSt., SanDiego, CA 92109) Modelsfor protecting marine mammals from noise have been suggested that are analogous tohuman noise criteria, specifically (1) weightingfunctions that model species-specific auditory threshold functions (analogous to A-weighting);(2) thresholdmodels for predictingthe proportion of individualsthat avoid a noise(analogous to the Schulz model of annoyance);and (3) theequal-energy hypothesisfor predicting hearing loss. Models for reducingsleep interference, speech interference, and attention deficits might also be applicable.All thesemodels will bereviewed. Unfortunately, human noise criteria do not apply to a numberof effectsthat could occur in free-rangingmarine mammals. Noise could affect nonauditory physiology. Noise could also mimic natural sounds (e.g., seismic impulsesthat are similar to tailbeats), or attractmarine mammals into dangerous areas (e.g., attracting killer whales to fishinggear). Giventhe paucity of researchavailable on noiseeffects in marinemammals, standards may be difficultto establish,although they are badlyneeded. At present,management agencies have adopted extremely conservative noise criteria. The experience of regulatingnoise in humancommunities suggests that such stringent criteria cannot be enforcedconsistently. Solutions that have proved practical for human communities will be reviewed. 9:05 3aAO4. Basicunderstandings of whale bioacoustics:Potential impacts of man-madesounds from oceanographicresearch. ChristopherW. Clark (CornellLab. of Ornithology,Bioacoust. Res. Program, 159 Sapsucker Woods Rd., Ithaca, NY 14850) The recentincreased public awareness and concernover the potentialimpact of acousticsources for oceanographicresearch, particularlythe source for theAcoustic Thermometry of OceanClimate (ATOC) study, has raised the difficult issue of assessingboth short-termand long-term effects. A baselinestudy in Kauai,HI hasbeen underway for two seasonsas partof the MarineMammal ResearchProgram associated with ATOC. This researchspecifically addresses the questions related to short-term(<4 months),small scale(<30-km radiuszone of influence)issues using traditional visual and acoustic field methods.This includesshore-based and aerial observations,passive hydrophone array tracking,and aerialsurvey methods. These efforts, conducted prior to any operationof an ATOC source,provide a baselinemeasure of the level of short-termimpact under "normal" conditionsoff Kauai, wherenormal includesregular exposure to noisefrom small craft, ships, helicopters, and airplanes. Potential long-term impact is addressedthrough statewideaerial surveys and through integration of theinter- and intra-seasonal variability of whalebehaviors and distributions. Results of the Kauairesearch will be presentedand discussed in termsof baselineimpact and the needfor standards. 9:25-9:40 Break 9:40 3aAO5.Marine mammals and ocean-acoustic experiments: A personal view from Monterey Bay. StanleyM. Flatt6 (Dept.of Phys.,Univ. of California,Santa Cruz, CA 95064) Experiencein presentingtechnical descriptions of the relationship between marine mammals and the Acoustic Thermometry of OceanClimate project to environmentalgroups, business groups, students, and researchers is described. ft is pointedout that the greatestgap in theknowledge base of thegeneral public is thelack of realizationthat low-frequency acoustic noise in theocean is at presentdominated by anthropogenicsources. [Work supported by ONROcean Acoustics.] 10:00 3aAO6.Auditory-evoked potentials for assessmentof hearing in marineanimals. S.H. Ridgwayand D. A. Carder(Biosci. Div., NavalCommand, Control and Ocean Surveillance Ctr., RDTE Div., Code 5107B, 49620 Beluga Rd., Rm. 200, San Diego, CA 92152) Brain-waveactivity (EEG) even at minutelevels recorded from the dolphin head surface may be processedin synchrony with soundto revealan auditory-evokedpotential (AEP). AEPs can provide objective information about the auditorysystem and many featuresare consistent across species so that experience with common laboratory animals and humans may be of helpin evaluating responses.Although AEPs do notrequire a behavioralresponse, they may be comparedwith behavioral responses assound is attenuatedtoward threshold. Some components of the AEP are unaffected by levelof consciousness,allowing their use to evaluate hearingin sleepinginfants and to determinebrain damage or braindeath. Auditory thresholds, and related information such as temporarythreshold shifts, are critical for evaluating the potential impacts of oceannoise pollution on marine animals. Most species thatare of concern,such as the great whales will notlikely be brought into the laboratory so that their auditory system can be studied; however,many opportunities exist for brief studies when such animals become stranded or entrapped.Physiological studies, including AEPs,could go a longway toward providing critical information needed to definesome limits for safe noise exposure for marine animals. 10:20 3aAO7.Whale ears: Structural analyses and implications for acoustictrauma. D.R. Ketten(Dept. of Otolaryngol.,Harvard MedicalSchool, MEEI, 243 CharlesSt., Boston,MA 02114) Over75 speciesof dolphinsand whales are spread throughout every aquatic habitat. Although echolocation abilities of some dolphinsare well documented, little is knownabout hearing in mostwhales. Dolphin signals range as high as 200 kHz, while baleen whalesroutinely produce 10- to 20-Hz signals. Whales have, therefore, two important auditory considerations: (1)the broadest signal 3269 J. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128th Meeting:Acoustical Society of America 3269 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp rangeof anymammal group; and (2) theonly mammalian ears adapted to underwaterhearing. In thisstudy, three-dimensional morphometricmodels of middleand inner ears from noncaptive toothed and baleen whales were used to estimate their hearing r•nges. The analysesshow echolocating species have basilar membrane stiffness coefficients 3X thatof bats.Baleen whales have stiffness coefficientslower than elephants that hear infrasonics. Ganglion cell densities in whalesare 2x batand 3x humanvalues. These data suggestecholocating dolphins may use multiple, parallel processed signal detection mechanisms. Cellular hypertrophy of inner ear supportstructures (stria vascularis, spiral ligament, basement membrane, etc.) in all whalesmay mean whales have inner ear mechanismsthatdecrease the potential for acoustic trauma. [Work supported by ONRGrant No. N00014-92-J-4000.] Contributed Papers 10:40 Theability to trackvocalizing whales over large distances (>100 kin) 3aAO8.Late nightfish choruses in the shallowwaters off SanDiego. usinghorizontal arrays has recently received much attention in theunder- G. L D'Spain,L Berger,A.M. Richardson,G. Clapp,and J. Rice wateracoustics community ["Use of NavalFacilities for OceanAcoustic (MarinePhys. Lab., Scripps Inst. of Oceanogr.,Mail Code0704, La Jolla, Research,"J. Acoust.Soc. Am. 95, 2851-2854(1994)]. The high source CA 92093-0701and NCCOSC.RTDE DIV, SanDiego, CA 92152-5001) levelsof the whales,up to 190 dB re: 1/xPa at 1 m, makethis possible. However,tracking vocal whales may providean incompletebehavioral Twomajor experLments, SWellEx-1 and aWeIlEx-3, and one engineer- picturebecause a significant proportion of whalesmay be nonvocalat any ing seatest recently have been conducted in 200-m-deepwater 8 miles giveninstance. (Visual observations are limited to thesmall proportion of west of the moulhof San Diego harbor.SWellEx-1 was conductedin time thatwhale s surface.)Alternatively, the high sourcelevels invite the Augustof 1993,the engineering sea test in May 1994,and SWellEx-3 in possibilityof treatingthe vocalizing whale as an active source. Sound from July1994. For both of thesummertime SWclIEx experiments, an unusual thissource of opportunitythat is scatteredby othermembers of the herd oscillationin thebackground levels between 275-550 Hz and575-700 l-lz maybe sufficientto locatenonvocal whales with a towedarray. Historical wasobserved, typically starting around midnight local time and lasting data are usedto model the spatialdistribution of vocal and nonvocal until sunrise.The repeatingpattern to the oscillationsis thatof a 3-5 dB humpbackwhales migrating off theEastern Continental Shelf of Australia. increasein spectrallevels, which lasts on the orderof 20 s, and then A spectralmodel for scatteringfrom an objectin a waveguidebased on followedby 25 s or so of lowerlevels. Azimuthal beamforming has indi- lngcnito'smethod is usedto determinethe scattered field from the whales. catedthat the predominant direction of this"cycling sound" is fromnear Waveguidenoise is modeledvia the Kupermanand lngenitoapproach. coastalwaters. In thedata from the May 1994engineering sea test, no such Simulationsindicate that localizationof nonvocalwhales is plausiblefor cyclingsound was present. The characterof thesesignals, i.e., theirspec- towedarrays within roughly 10 km of the herdin typicalambient noise tral content,their diurnalvariation, their seasonalvariation, and their di- conditions.This rangemay be extendedsignificantly with time-domain rectionality,correspond to thosedescribed in year-long,single-hydrophone matchedfiltering. measurementsmade from a shallowwater toweroff San Diego in the early 1960sand ascribed to soundsmade by fishof the croakerfamily [G. A. Clapp,NEL TechMem 1027(1966}]. Additional properties of thesesig- 11:10-11:15 Break nals,including a recordingof thesounds made by a singleindividual, will bepresented. [Work supported by ONRCode 321.] 11:15-12:15 10:55 PANEL DISCUSSION: 3aAO9. Using singlhg whales to track nonsingers. NicholasC. Panel Moderator: Charles R. Greene, Jr. Makris (Naval ResearchLaboratory, Washington, DC 20375) and Panel Members: Ann E. Bowles, ChrislopherW. Clark, William F. DouglasH. Cato (DefenceSci. and Technol. Organization, Pyrmont, Dolphin,Jeannie Drevenak, Carol Fairfield, Stanley M. Flatt6,Darleen R. NSW 2009, Australia) Ketten, Bruce R. Mate, Sam H. Ridgwa¾,Ann Terbush WEDNESDAY MORNING, 30 NOVEMBER 1994 SAN ANTONIO ROOM, 8:30 TO 11:35 A.M. Session 3aEA EngineeringAcoustics: Acoustical Measurement and Instrumentation I GeorgeS. K. Wong,Cochair Institutefor NationalMeasurement Standards, National Research Council, Montreal Road, Ottawa, Ontario K1A OR6, Canada J. S. Echeverr/a-Villagomez,Cochair CentroNaciohal de Metrologia,km 4.5 Carr,Los Cues, Mplo. El Marquds,Querdtaro, CP 76900,Mexico " Chair's Introductions8:30 Invited Papers 8:35 3aEAI. Progressin acoustictransducer design and calibration. GunnarRasmussen (G.R.A.S. Sound & Vibrationaps, Vedbaek, Denmark) TheaCcuracy ofacoustic measurements willplay an increasing role,if legislation,prediction, andnoise control are to be taken seriously.If the trafficintensity is doubledby year2000, oneshould expect a 3 dB highernoise level, unless the emittedsound power 3270 J. Acoust.Soc. Am., VoL 96, No. 5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3270 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp fromeach vehicle is reducedby 3 dB.It is unlikelythat emitted power will becut in half,unless a numberof sourcesthe sum of which is halfare attacked. This calls for betterand more accurate measurements. Better monitoring equipment and better source location and sourceranking equipment is needed.Outdoor monitoring has undergone a development to morerugged, stable, and accurately calibratedsystems. Intensity measurements aregetting out of thecrib. Standards have evolved and calibration procedures are starting to beevolved. Instrumentation has been improved. It is importantthat intensity probes can now be producedto narrowspecifications tofulfill the demand for precise and reproducible measurements; theyare no longer selected from large populations, but manufactured to exactspecifications. It is importantto makeproper calibrations, not just assume that certain parts of a probeare working properly. If intensitymeasurements shall gain in popularityit is importantto developthe instrumentation from magic machines into practical toolsfor the practitioner.Practical systems, calibration, and applications will be discussed. 9:05 3aEA2. Free-fieldcalibration and characterizationof microphonesystems. Victor Nedzelnitsky (Natl. Inst. of Stds.and Technol.,Sound Building 233, Rm. A147, Gaithersburg, MD 20899-0001) Significantdiscrepancies occurred in resultsfrom the recent European intercomparison of free-field calibration of IEC typeLS2aP (13.2mm nominal diameter) laboratory standard microphones [K. Rasmussenand E. SandermannOlsen, The Acoustics Laboratory, TechnicalUniversity of Denmark(DTH) ReportPL-07 (1993)]. Consequently, Dr. RichardBarham of theNational Physical Labo- ratory,U.K. (NPL) visitedNIST to resolveone suchdiscrepancy between NPL andDTH by obtaininga NIST calibrationof a microphonethat also had been calibrated by NPLand DTH in theEuropean comparison. All laboratoriesused the reciprocity method, with independentlyimplemented apparatus at eachlaboratory. The NIST calibrationagreed relatively well with thatof DTH, but not NPL, if all laboratoriesused the samevalues for the frequency-dependentacoustic center positions of the microphones.The prob- lematicalDTH andNPL determinationsof acousticcenter positions for thetype LS2aP microphone, which disagree with the values obtainedby scalingthe positions standardized for anothermicrophone type, are considered. Various implications for thecurrent draft IEC standardon primaryfree-field calibration are discussed.Selected NIST free-fieldcomparison calibration methods and transducer characterizationprocedures, recently applied to relativelynovel devices such as micro-machinedsilicon microphones, are described. 9:35 3aEA3. Microphonemonitoring by chargeinjection calibration. ErlingFrederiksen (B&K Res.and Develop. Dept., 2850 Naerum,Denmark) Chargeinjection calibration is a new methodfor monitoringoperation conditions of measurementchains consisting of a micro- phonewith preamplifier,cables, and conditioning amplifier. The methodreplaces the insert-voltagecalibration technique which is frequentlyused with large or unmannedsystems. A greatadvantage of thenew method is its abilityto checkthe transducer which is practicallyignored by theinsert-voltage calibration. From a remotevoltage source, a constantcharge is "injected"into the microphone capacitanceand preamplifier input circuit using a smallcapacitance integrated with thepreamplifier. This leads to anoutput signal that is inverselyproportional to thecombined impedance of thetransducer and input circuit. An accidentalchange in themicrophone impedance--whichis a goodtransducer condition indicator--would appear as a changein thepreamplifier output. High stability and extremelyhigh leakage resistance (typically 10141).) are required for the charge injection capacitor (typically 0.2 pF). This problem was solvedand the (patented) method was found to workreliably over a widefrequency range (2 Hz-200kHz). The new method is less costlyand simpler to implement.It also preserves the systems resistance to extraneous electrical fields. The method and its ability to indicatemalfunctioning are discussed. 10:05 3aEA4. Traceabilityof acousticsand vibrationsstandards at the National Center of Metrology in Mexico. J.S. Echeverrla-Villagomez(Centro Nacional de Metrologia, km 4.5 Cart, Los Cues, Mplo. El Marqu•s,Queretaro, CP 76900, Mexico) Afterthe creation of the MexicanPrimary Laboratory of Metrology,primary standards on acousticsand vibrations are being establishedfor thefirst time in thecountry. For this task, CENAM staff has relied on thetechnical assistance of the corresponding groupsat NIST and NRC. The process has involved several specific features due mainly to the particular needs and conditions of the Mexicanlaboratory. On the acoustics side, for the instrumentation of the reciprocity method for microphonecalibration, the altitude of thesite at whichCENAM is locatedand the consequent low pressure lead to theproposal for a pressure-controlledchamber. Both theproposal and its completion has been carried out at NIST,with direction of itsstaff and participation of CENAM staff. The stage in whichthe project is atthe moment will be shown. Also the instrumentation andmethods used for giving traceability from CENAM to transferand working standards of externalcustomers. On the vibrationsside, instrumentation of the reciprocitymethod for accelerometercalibration has been achievedwith the BoucheLabs 5000CR system.Besides an interferometricsystem is being obtainedasa complementaryaidand for cross checking purposes. Traceability totransfer and working standards atCENAM is already beingaccomplished through the comparison method. An evaluation of thesystems performance will bepresented and a firstestimation of their uncertainties will be discussed. 10:35 3aEAS.Velocity of soundmeasurement in liquids. Zhu Shi-ming (Inst. of Acoust., Tongji Univ., Shanghai, People's Republic of China)and GeorgeS. K. Wong(Inst. for Natl. Measurement Stds., Natl. Res. Council, Ottawa, ON K1A 0R6, Canada) Soundvelocities in purewater at varioustemperatures were measured. A PZT transducer sends a 2-MHzpulse towards a target stationedat anaccurately known distance of 120mm away. The transit time between the forward pulse and the reflected pulse was measuredprecisely with statistical averaging and a referencetimebase derived from the NRC cesium frequency standard. The 3271 J. Acoust.Soc. Am., Vol. 96, No, 5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3271 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp transducer-targetprobe and liquidchamber was immersedin a temperaturecontrolled bath that was underthe controlof a computer. Measurementswere repeatedwith knownconcentrations of alcoholand distilled water. Uncertainties of the measurementswill be discussed.The authorswould like to thankLu-Jie of theTongji University for his contributionto the constructionof themeasurement circuits. 11:05 3sEA6, Considerationsof errors in computer-basedmeasurements. Alan D. Wallis (CirrusResearch pie, AcousticHouse, HunmanbyYO14 0PH, UK) The useof computershas come to dominateacoustical measurements aswas predicted at ICA 1983in Paris.However, what was notpredicted was that a generationof acousticianswould arrive with no previousexperience of olderanalogue systems. 'to someof thesenew generationworkers, "the computeris alwaysright" and little or no thoughtis given to the limitationsand accuracy restrictionsof a totallydigital system.Automatic checks routinely done before and after measurementson previousgenerations of instrumentsare sometimes ignored, while instrumenttolerances are assumedto be zero andcalibrations are assumedto be perfecteven thoughlogic suggestsotherwise. Consideration is givento makingbasic checks on computerbased instruments, so that reasonable reliancecan be placedon the results,often usingold and traditionalmethods brought up to data and translatedfrom the analogueto the digitalworld. Sample case histories of particular"real world" errorsare given, with someidea of the practicallimitations of new technologyinstrumentation and where they sometimes fall shortof olderunits. These are compared with somerequirements of ANSI and international standards. WEDNESDAY MORNING, 30 NOVEMBER 1994 SAN MARCOS ROOM, 8:20 A.M. TO 12:05 P.M. Session 3aNS Noise:Nonoccupational Noise Exposures and Implicationsof RecentTLV Changes Larry H. Royster,Cochair MAE Department,North CarolinaState University,Raleigh, North Carolina 27695-7910 Julia D. Royster,Cochair EnvironmentalNoise Consultants,Inc., PO. Box 30698, Raleigh, North Carolina 27622-0698 Chair's Introductions8:20 Invited Papers 8:30 3aNSI. On comparingnoise metrics applied to hearingconservation. John J. Earshen(Angevine Acoust. Consultants, Inc., 1021 Maple St., P.O. Box 725, EastAurora, NY 14052-0725} A numberof differentmetrics are in usefor measuringand reportingexposure to noisefor heatingconservation including noise dose,time-weighted average level, soundexposure, and soundexposure level. Functionsfor computationof individualmetrics from measurementof acoustic pressure vary widely. Functions defining particular metrics in someinstances contain choices of parameters (e.g.,exchange rates and threshold levels). In mostinstances, once a metrichas been evaluated for a particulartime profile of acoustic pressure,it is not possibleto convertit to anothermetric if the originaltime functionis not retained.In additionto the defining functions,dynamic and frequencyresponse characteristics of measuringinstruments have influenceson resultsobtained and can presentobstacles to conversionamong metrics. Large bodies of dataexist which only contain the finally processed metric. The degree to whichcomparisons can be made because of recentchanges in TLV requiresinferential interpretation of the values of specificmetrics whichare produced by time functionsthat are identified only in a statisticalsense. This paperexamines the inferentialrelationships amongprominent met fica for various classes of sound-pressureprofiles as obtained with measuring instruments meeting ANSI andlee performancestandards. 8:55 3aNS2,Noise exposures in U.S. coalmines. JohnP. Seiler,M.P. Valoski,and M. A. Crivaro (U.S. Dept.of Labor,MSHA, P.O. Box 18233,Pittsburgh, PA 15236) MineSafety and Health Adminislration (MSHA) inspectors conduct full-shift environmental noise surveys to determinethe occupationalnoise levels to which coal miners are exposed. These noise surveys are performed to determinecompliance with the noise standardpromulgated under the Federal Mine Safety and Health Act of 1977.Data-from over 60 000 full-shift noise surveys conducted 3272 J.Acoust. Soc. Am., Vol. 96, No.5, Pt.2, November1994 128thMeeting: Acoustical Society of America 3272 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp fromFiscal Year 1986 through 1992 were entered into a computerdatabase to facilitateanalysis. This paper presents the mean and standarddeviation of over60 000 full-shiftnoise dose measurements for variousunderground and surface coal mining occupations. Additionally,it comparesand contrasts the levelswith historicalnoise exposure measurements for selectedcoal mining occupations thatwere published in the1970s. The findings were that the percentage of minerssurveyed that were subjected to noiseexposures above100%, neglecting personal hearing protectors, were 26.5% and 21.6% for surfaceand undergroundmining, respectively. Generally,the trendis thatthe noiseexposures for selectedoccupations have decreased since the 1970s. 9:20 3aNS3. Comparison of daily noise exposuresin one workplace based on 3-dB vs 5-dB exchangerates and criteria recommendedby the ACGIH versusOSHA. MichellePetrick (OccupationalHealth and Safety, IBM, Dept.692, Bldg.002, P.O. Box 12195, ResearchTriangle Park, NC 27709), Larry Royster (NC State University,Raleigh, NC), Julia D. Royster (EnvironmentalNoise Consultants, Inc., Raleigh,NC), and ParkerReist (UNC, ChapelHill, NC) In May 1994,the American Conference of GovernmentalIndustrial Hygienists (ACGIH) recommendedas a thresholdlimit value (TLV) for noiseexposure an 8-h equivalentlevel of 85 dBA, basedon a 3-dB exchangerate. The U.S. Departmentof Labor's OccupationalSafety and Health Administration (OSHA) requires that employees be includedin a hearingconservation program (HCP) if their8-h time-weightedaverage (TWA) noiseexposure equals or exceeds85 dBAbased on a 5-dBexchange rate. To investigatethe numberof additionalemployees who wouldbe includedin the HCP at one industrialfacility if theACGIH TLV wereused, new personaldosimetry samples were collectedfor all noise-exposedemployees. Employees at this facility have low noiseexposures characterizedby time-varyingor intermittentnoise and impactcomponents. To allow analysisof eachsample using both exchange rates,each monitored worker wore either two single-settingdosimeters or one double-settingdosimeter. Based on this data the potentialimpact if OSHA changedits presentprocedures for determiningemployee noise exposure will be presented. 9:40 3aNS4. The impact of using a 3-dB vs 5-dB exchangerate on the predicted employee's8-h equivalent A-weighted sound-pressurelevel in threedifferent types of industrialwork environments.Larry H. Royster(MAE Dept.,NC StateUniv., Raleigh,NC 27695-7910)and JuliaDoswell Royster (EnvironmentalNoise Consultants, Inc., Raleigh, NC 27622-0698) A noiseexposure database was previouslycollected using a 5-dB exchangerate for three differenttypes of industrialwork environments:paper manufacturing, aluminum casting and rolling, and meat packaging. This databasewill be reanalyzedto estimate theimpact on thepercentage of additionalemployees that would have to be includedin eachcompany's hearing conservation program if a 3-dB exchangerate replacesthe presentOSHA 5-dB exchangerate. In addition,the effectof usingdifferent combinations of criterionand action levels in conjunctionwith the useof a 3-dB exchangerate will be discussed. 10:oo 3aN$5. Contribution of off-the-job noise to hearing thresholdsof employeeswith occupationalnoise exposure. Julia D. Royster (EnvironmentalNoise Consultants, Inc., P.O. Box 30698,Raleigh, NC 27622), LarryH. Royster (NC StateUniversity, Raleigh,NC 27695), PamelaS. Calliari (AssociatedHear. Services, Raleigh, NC), and Kelly L. Tennyson(Developmental EvaluationCtr., Raleigh,NC) Employersoften assert that it is fruitlessto protectemployees from noise at workbecause workers' off-the-job noise exposures are sufficientto causesignificant heating loss. Certainly, the lowerthe actionlevel for includingemployees in a hearingconservation program(HCP) is set,the greater the potential contribution of nonoccupationalexposures becomes. This paper will describethe types of nonoccupationalnoise exposures reported by employees in HCPs at several industries on annual auditory history questionnaires and in interviews.In orderto evaluatethe contribution of nonoccupationalnoise exposure to workers'hearing thresholds, employees were groupedaccording to theirself-reported amount of off-the-jobnoise. Results of analyseson age-correctedhearing levels will be presented. 10:15 3aNS6.Nonoccupational noise exposures and estimateddaily Leq values for attendanceat collegebasketball games and shoppingcenters. LarryH. Royster (MAE Dept.,NC StateUniv., Raleigh, NC 27695-7910)and JuliaDoswell Royster (EnvironmentalNoise Consultants, Inc., Raleigh,NC 27622-0698) Noiseexposure data were collected during 1988-1989 home basketball games at NorthCarolina State University. Thirteen exposuresamples averaging 2 h in durationwere collected utilizing Larson-Davis 700 noise dosimeters. Measured noise level results wereas follows: average unweighted peak pressure was 133.1 dB, averagemaximum sound level (L^) was115.2 riB, and average LAeq2hwas 97.1 dBA. The equivalent 40-h exposure level LAeq4 oh was 84 dBA.As another example of nonoccupationalnoise exposure,between 1982 and 1994 seven shopping malls in fourdifferent cities were visited to establishthe sound level distributions. Over800 noise level samples were obtained. When the data were restricted to mallswith at least500 000 sq ft, it wasdetermined that measurednoise levels LA could be approximated utilizing the following equations (where N is thenumber of shopperswithin a radius of7.6 m of the measurement location): LA=61+10 1og(Nø'S5), forN•<10, and L^=54+10 1og(N•'2ø), forN>10. 10:35-10:•0 Break 3273 J. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128th Meeting:Acoustical Society of America 3273 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp ContributedPapers 10:50 The U.S. Army EnvironmentalHygiene Agency Technical Guide 181 on noisedosimetry and risk assessmentwas developedas a guidefor evalu- 3aNS7. Noise exposuremeasurements of the Tokyo String Quartet. atingtypes of noiseexposure patterns and includes sampling strategies for LarryH. Royster(MAE Dept.,NC StateUniv., Raleigh, NC 27695-7910) dosimetrymeasurement of TWAs. The statisticalbasis of the sampling and Julia DoswellRoyster (EnvironmentalNoise Consultants,Inc., approachwill be discussedin somedetail. Other changesin the Army Raleigh,NC 27622-0698) hearingconservation program resulting from the adoption of theTLVs will Duringthe Spring1994 Meeting of ASA a specialconcert was given be outlined. by theTokyo String Quartet. During the first part of theprogram the Tokyo StringQuartet played two musicselections using each of fourdifferent sets 11:35 of instruments:Old Italian instrumentsand moderninstruments crafted by CarleenHutchins, Curtin andAll, and Robertand Decna Spear.The Tokyo 3aNSI0. Active noise reduction for cireumaural hearing protectors StringQuartet had previously agreed to allow noisedosimeter monitoring by digital feedforward control. G. J. Pan, A. J. Brainmet,J. Ryan, J. of their exposuresduring the first half of the program.In addition,one Zeta (Inst. for Microstruct.Sci., Natl. Res. Council, Montreal Rd., memberof the audiencealso wore a noisedosimeter during the perfor- Ottawa, ON K1A 0R6, Canada),and R. Goubran (CarletonUniv., mance.The measured L(•q) values across instrument groups for the audi- Ottawa,ON K1S 5B6, Canada} encemember exhibited a rangeof 0.7 dBA for the firstmusical selection A commercialanalog active noise reduction (ANR) communication and 0.6 dBA for the secondselection. The remainingrecorded database headset,constructed using a cireumauralhearing protector, has been modi- findingsand its analysiswill be presented.The authorsare grateful to the fiedto explorethe performanceof a digitalANR systemfor thisapplica- membersof theTokyo String Quartet for allowingthem the opportunity to tion.The apparatusretains one ear cup andcushion, together with the obtainadditional musician noise exposure information. earphoneand attached microphone of the commercialdevice. The sound fieldoutside the earcup is sensedby a miniaturemicrophone attached to 11:05 the exteriorof the ear cup,and formsthe "reference"signal. This signalis fed forwardto an adaptivecontroller, which drives the earphone within the 3aNSS. Investigationof lawn-maintenanceequipment noise. Gordon ear cup. Controlof the soundpressure within the volumeenclosed by the T. LopIcy,IV andL. MarcelynBruce (Collaborationin Sci.and Technoi., hearingprotector is maintainedby an "error" microphoneattached to the Inc., 15835 ParkTen Place,Ste. 105, Houston,TX 77084-5131) earphone,using the filtered-X LMS algorithm.The error-pathimpulse As the lawn-maintenanceindustry grows in suburbanresidential areas, responseis identifiedoff-line. A TexasInstruments TMS320c31 floating it hasbecome a new and significantsource of environmentalnoise and pointdigital signal processor has been used to implementthe controlsys- occupationalnoise exposure. Due to the shortduration at any onelocation tem in realtime. The noisereduction of the adaptivedigital system will be andpublic acceptance of thisactivity, there are few communitycomplaints discussedwhen the hearingprotector is subjectedto bandlimitednoise in aboutthe noise (except at unreasonablehours). This paper will concentrate thefrequency range from 50 to 1000l-Lz. [Work done in collaborationwith on recreationaland occupational exposure, where individuals are exposed theDefence and Civil Instituteof EnvironmentalMedicine, Toronto, Ont.] to high noiselevels for long periodsof time. Most lawn-maintenance workersspend from 8-10 h per day exposedto A-weightedsound levels 11:50 greaterthan 85 dB, and it appearsthat few employeeswear hearingpro- tection.Sound levels were measuredand monitoredat the operator'sear 3aNSll. New methoddose for a 24-h estimationof occupationaland and measuredat a distanceof 10 ft for the followingequipment: lawn nonoccupationalnoise. AlexanderA. Menshey (Dept.of Phys.Factors, mowers,gas and electric edgers, gas and electric trimmers, electric blow- Inst. for OccupationalDiseases, 252033 Kiev, Ukraine) ers,and an electrichedge trimmer. A-weighted sound levels at the opera- Over 24 h the influenceof occupationaland nonoccupationalnoise tor's ear rangedfrom 82 to 102 dB. A comparisonof equipmentsound maybe distinguishedby threeperiods: job, rest,and sleep. If the levelof levelswill be presentedas well as a comparisonof noiselevels for gas noisefor eachperiod is describedin dBA thereis no possibilityof sum- versuselectric lawn equipment.Finally, daily noiseexposure for lawn- ming up theselevels and receivingmean arithmetical values (average maintenanceemployees will be developedusing the data. daily) becausedBA is a logarithmicvalue. But if onedescribes levels of noisein dosesthere is a possibilityof receivinga "medium-weighted" 11:20 dose of noise lead for 24-h because the doses are arithmetical values and it is possibleto sum up and divide the total. If the doselevel duringthe 3aNS9. Sampling strategy for noise dosimetry measurements. Felix Z. Sachs (U.S. Army Ctr. for HealthPromotion and Preventive Medicine workis 1 dose-80 dBA, at rest1 dose-40 dBA (onedose), and during (Provisional),Aberdeen Proving Ground, MD 21010-5422) sleep1 dose-30 dBA (Ukraineand Russian sanitary standards), then the medium-weightedsanitary standard for the 24-h level of noiseis one dose. The U.S. Army hasadopted most of the new ACGIH TL¾s as criteria The increaseof the level for eacha third24-h periodat 3 dBA abovethe in its hearingconservation program. Most significantto theArmy program norm will increasethe dose level twice (two doses);at 6 dBA it will was the changefrom a non-time-weightedinclusion criterion to the 8-h increaseto fourdoses; at 9 dBA it will increaseto eightdoses; at 12 dBA, time-weightedaverage noise exposure level (TWA). The TWA mustnow to sixteendoses, etc. If suchhigh doses for each period are summed up and be identifiedfor all Army civilianpersonnel subjected to hazardousnoise arethen devised in three,a realmedium-weighted dose of noiselead for 24 exposureand for soldiersworking in noise-hazardousindustrial operations. h above the standard,which is 1 dose, will be found. This method is This can be accomplishedwithout making noise dosimetry measurements simplerthan estimatingthe noig• load abovethe •tandardfor each third on everysingle individual suspected of beingexposed to hazardousnoise. periodof a 24-h influenceof noise. 3274 J. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3274 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp WEDNESDAY MORNING, 30 NOVEMBER 1994 WEDGWOOD ROOM, 8:00 A.M. TO 12:00 NOON Session 3aPAa Physical Acoustics: Outdoor Sound Propagation Michael J. White, Chair U.S. Army ConstructionEngineering Research Laboratory, P.O. Box 9005, Champaign,Illinois 61826-9005 ContributedPapers 8:00 Reportedhere is a numericalinvestigation to explainexperimental observationsof the effectof turbulenceon N wavepropagation lB. Lip- 3aPAal. Detectionof direct and indirect sonic booms from space kens,Ph.D. thesis, Mech. Eng. Dept., Univ. of Texasat Austin (1993)]. An shuttle landings. JosephCates, B. Sturtevant (GraduateAeronaut. adaptationof VonKfirmfin's spectral model for incompressible,isotropic Labs.,California Inst. of Technol.,Caltech 301-46, Pasadena,CA 91125), turbulenceis usedto generatea statisticalrealization of a turbulentfield. Hiroo Kanamori (CaliforniaInst. of Technol.,Pasadena, CA 91125), and The 2-D, random,isotropic velocity or temperaturefields consistof a J. Mori (U.S. GeologicalSurvey, Pasadena, CA 91106) collectionof discreteFourier velocity modes [Ph. Blanc-Benonet al., Two hundredseismic stations covering over 50 000 squarekilometers Theoret.Cornput. Fluid Dynamics 2, 271-278 (1991)].The nonlinear in SouthernCalifornia were usedto analyzethe sonicboom patterns from propagationmodel consists of twoparts: (1) Lineargeometric acoustics is the landingof STS-42 in November1993 and STS-58 in January1994 at usedto tracerays through each realization of theturbulent field, and (2) a EdwardsAir ForceBase (EAFB). The instrumentground motion traces nonlineartransport equation is derivedfor thepropagation along the eigen- showseparate arrivals which can be identifiedas the primaryboom, creep- raysand solved by a Pestorius-typealgorithm. The inputwaveform to the ing wavesgenerated at the edgeof the primaryboom carpet, and multiple algorithmis a planeN wave similarto that usedin the modelexperiment indirectsonic booms refracted from high altitude.The measuredarrival to simulatesonic boom propagation through a turbulentatmosphere. Sta- times are comparedwith the results of linear ray tracing calculations tisticsof peakpressure and rise time, parametersthat determinethe loud- ness of sonic booms, are calculated over 100 realizations. The effect of throughreference temperature and wind profilesfor EAFB. The ray cal- culationsaccurately predict the measuredarrival times and wavefront turbulenceis to reducethe nonlineardistortion of the N wave. On average, angles for the primary sonic boom and the creepingwaves in shadow turbulencereduces peak pressure and increases rise time. Qualitatively, the regions,and accuratelypredict the wavefrontangles for the indirect sameconclusions are observedas in the modelexperiment. booms.Ray theoryusing the referenceatmosphere fails to predictindirect boomarrival time, observedmultiple booms within the first shadowre- 8:45 gion,and extensive overlap of the multiplyrefracted sonic booms. These resultssuggest that boom exposureunder the real atmospheremay be 3aPAa4. A numerical study of random focusingfor plane waves largerthan previouslyexpected. propagating in scalar or vectorial turbulent media. Philippe Blanc-Benonand Daniel Juv6 (Lab.de M6can.des Fluides et d'Acoust., URA-CNRS 263, BP 163, Ecole Centtalede Lyon, 69131 Ecully Cedex, 8:15 France) 3aPAa2. Sonic boom rise time. Robin O. Cleveland and David T. A numericalsimulation has been developed to investigatethe random Blackstock (Appl. Res.Labs. and Mech. Eng. Dept., Univ. of Texasat focusingfor an acousticplane wave propagating through scalar or vectorial Austin, P.O. Box 8029, Austin, TX 78713-8029) turbulentfields. The turbulenceis representedas a set of realizationsof randomfields (temperature or incompressiblevelocity) generated by a The rise time of a sonicboom shock in air dependsstrongly on the limitednumber of randomFourier modes [M. J. Karweitet al., J. Acoust. relaxationprocesses of nitrogenand oxygen.Stratification of the atmo- Soc.Am. 89, 52-62 (1991)].Through each realization the propagation of sphereleads to significantvariation of the relaxationprocesses with alti- a planewave is consideredin eitherthe geometricor the parabolicap- tude.J. Kang [Ph.D. thesis, Penn State (1991)] argues that the shock profile proximation.Using the ray equationsthe ray trajectoriesand the location canadjust quickly enough to changesin attenuationthat it alwaysappears of the instantaneouscaustics are computed. The acousticpressure field and to be in steadystate. If correct,then rise time at the groundcan be calcu- the intensityfluctuations ate obtainedby solvinga wide-angleparabolic latedfrom local conditions only. A timedomain computer algorithm, based equation.Ensemble averaging is thenperformed to evaluatethe probability on workby Lee andHamilton ("Time domainmodeling of pulsedfinite- distribution of the occurrence of caustics and the variance of acoustic amplitudesound beams," submittedto J. Acoust. Soc. Am. in March intensityfluctuations. For 2-D and3-D scalarsimulations the results dem- 1994),is presentedfor a Burgers-typeequation. The algorithmincludes the onstratethat the positionof causticsas well as the maximumpeak in the effectsof nonlineardistortion, thermoviscous absorption, molecular relax- scintillationindex are governedby universalparameters related to the ation,and ray tube spreading. A parametricstudy of theeffect of changein transversespatial derivatives of thecorrelation function of thefluctuating relativehumidity shows that the steady-state assumption is notjustified for componentsof the turbulentmedium. Results will be givento generalize sonicboom shocks in theatmosphere. A sonic boom propagated through a the definitionof theseuniversal parameters for soundpropagation in ran- realatmosphere is shown to havea risetime that, in all casesrun so far, is domvelocity fields. shorterthan that of a steady-stateshock calculated using atmospheric prop- ertiesat theground only. [Work supported by NASA.] 9:00 8:30 3aPAa5. Short term fluctuations in the sound field within a shadow region near the ground. David I. Havelock (Inst. for Microstruct.Sci., 3aPAa3. Weakly nonlinear propagation of N waves through Natl. Res. Council, Ottawa ON K1A 0R6, Canada) turbulence. Bart Lipkens (Macro-Sonix,1054 Technol.Park Dr., Glen Allen, VA 23060)and PhilippeBlanc-Benon (Ecole Centtale de Lyon, An acousticshadow region can be creatednear the groundby an 69131Ecully Cedex, France) upwardlyrefracting atmosphere or maskingby prominentterrain features. 3275 d. Acoust.Soc. Am., Vol.96, No. 5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3275 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp Acousticenergy arrives deep within the shadowregion principally by "boundarywaves" due to cohcremscattering. However, roughness in the scatteringfrom turbulence in the insonifiedregion above the shadow. It is brightzone causes less sound to propagateinto the shadowzone of the expectedthat the structureand dynamics of the turbulenceultimately partially roughsurface, relative to the curvedsmooth surface, because of terminc the characteristics of the sound field observed in the shadow re- incoherentscattering. [This work is supportedby a Fannieand John Hertz gion.By identifyingobservable characteristics of thissound field, it is Fellowship.]')Current address: National Center for PhysicalAcoustics, hopedthat usefulrelationships between meteorological dynamics and University,MS 38677. soundfield fluctuationswithin the shadowregion can be established.A largearray of microphoneshas been deployed on an asphaltranway to 10:00-10:15 Break investigatethe soundfield fluctuationsin a refractiveshadow. The fre- quencyrange being investigated is 40-1000 Hz, at rangesup to 700 m. The evolutionof the soundfield over the period of a few secondsis 10:15 discussed.Examples of the observedsound field arepresented. 3aPAa9. Estimation of time-varying phase for multiple tones in atmosphericsound propagation. JohnC. Burgess (Dept. of Mech. 9:15 Eng.,Univ. of Hawaii,2540 Dole St., Honolulu,HI 96822}and David L Havelock (Natl. Res. Council,Ottawa, ON K1A 0S1, Canada) 3sPAn6.Atmospheric sound propagation in a turbulent atmosphere over irregular terrain. Xiao Di and KennethE. Gilbert (Appl.Res. Atmosphericturbulence affects both the amplitudeand phase of trans- Lab.and the Graduate Program in Acoust.,Penn State Univ., P.O. Box 30, mired sound.Tones at differentfrequencies will be affeeteddifferently. In StateCollege, PA 16804) an earlierpresentation [J. C. Burgessand D. I. Havelock,"Estimation of time-varyingphase (instantaneous frequency} in atmosphericsound propa- A phasescreen method for atmosphericturbulence and a cascaded gation,"J. Acoust. Sec. Am. 95, 2838(A)(1994}], the time-varying phase conformalmapping technique for irregularterrain are usedtogether to of a singletone was estimated by two methods,one based on an FFT with investigatescattering of soundby turbulenceinto a terrain-generated optimumdata windows, the otherbased on the discreteHilbert transform. shadowzone. Comparisons with and withoutatmospheric turbulence are In this presentation,the optimumdata window methodis extendedto madefor frequenciesfrom 50 to 500 Hz. It is shownthat with thenear- multipletones. Accuracy of the methodis examinedusing a synthesized gronndturbulence model of Daigleand a hill similarto thatin theJoint signalwith and withoutadditive noise. AcousticPropagation Experiment (JAPE), turbulence effects are negligible belowapproximately 125 Hz. Above125 Hz, thereis considerablescat- 10:30 teringinto the shadow zone behind the hill. Forthe data currently available from the JAPE measurements,the theoreticalpredictions are in good 3aPAa10. Helicopter field data compared with fast field program. agreementwith experiment. [Work supported by theArmy Research Labo- MichaelT. Barnes (U.S. Army Res. Lab., BattlefieldEnvironment ratory.] Directorate,White Sands Missile Range, NM 88002) A studywas conducted to comparethe fast field program (FFP) to data 9:30 obtainedfrom helicopters.The purposeof the studywas to seehow well 3aPAa7. Scatteringof sound by turbulenceinto a shadowregion. FFPpredictions would compare to helicopterdata over ranges out to 20 km Michael R. Stinson (Inst. for Microstract. Sci., Natl. Res. Council, and determineif the FFP couldbe usedto reliablypredict the propagation Ottawa, ON K1A 0R6, Canada) conditionsfor acousticarrays listening for helicopters.Over a periodof 2 weeksacoustic data from severalhelicopters with variousflight pathsout The soundfield aboveground due to a point sourcein an upwardly to a rangeof 20 lornwas recorded.At the sametime meteorologicalcon- refractingatmosphere has been computed to determinethe natureof tur- ditionswere alsonoted. These included temperatures up to 400 m, relative bulentscattering into an acousticshadow •egion. A Green'sfunction para- humidity,barometric pressure, wind speed,and wind directionup to 2000 bolicequation (GFPE) method that includes turbulence via a phasescreen m. The resultswere very promisingand in mostcases provided a good approachIX. Di and K. E. Gilbert,J. Acoust.Sec. Am. 92, 2405(A) comparisonuntil the helicoptersignal was burledin backgroundnoise. (1992)] is usedfor thesimulations. Flat groundwith finitesurface imped- anceand a logarithmicsound-speed profile are assumed,and propagation 10:45 rangesof 1 krn areconsidered. Different realizations of a turbulentatmo- spherewere generatedemploying a Gaussianspectrum to describethe 3sPAall. Sensitivity analysis of the Green's function parabolic turbulence.For 500-Hz sourceIones, it was foundthat the componentsof equation model for atmospheric sound propagation. Michael R. the turbulencespectrum that contributedmost to the scatteredfield in the Dobry (Dept.of Mech.Eng., New MexicoState Univ., Box 30001-3501, acousticshadow region corresponded to dimensionsof theorder of 2-5 m; Las Cruces,NM 88004}, RobertP. Hansen (U.S. Military Academy, this scaleof structurecan be understoodin termsof a Braggreflection WestPoint, NY), and David H. Marlin (U.S. Army Res.Lab., White condition.The soundpressure at a receiverposition in theacoustic shadow SandsMissile Range, NM) appearsto bedominated by contributionsfrom a smallnumber of localized scatteringregions. A sensitivityanalysis was performed on theGreen's function parabolic equation(GFPE) model to determineparameter bounds which maimain modelvalidity. To determinethese bounds, inverse theory was usedto 9:45 determinethe "best" combinationof input parametersover a two- dimensionaldomain using a normalizedsum of squaredresiduals. A two- 3aPAaS. Scale model experimentson the diffraction and scattering of soundby a partiallyrough curved surface. James P. Chambers,a) dimensionalversion of the fast field program(FFP), a widely accepted Yves H. Berthelot.and T. ShaneStone (Schoolof Mech_Eng., Georgia atmosphericpropagation model, was usedas comparison. Plots of the error Inst. of Teehnol.,Atlanta, GA 303324MO5) surfacewere then made to show sensitivitybounds. Upward and down- ward refractingatmospheres were consideredfor a rangeof frequencies. Scalemodel experiments have been conducted to studythe propagation The GFPE model was found to requirea height incrementparameter of of soundover a curvedsurface partially covered with rigid randomrough- about0.05 wavelengthswhile the rangeincrement parameter extended nesselemenls in the high-frequencydiffraction/low-frequency scattering from 10 to 120 wavelengthsdepending on atmosphericprofile and fre- regime.The effectsof roughnessare found by comparingthe soundfield quency.The thicknessof the attenuationlayer was foundto be frequency with thatobtained with a fully smoothcurved surface. Experiments indi- dependentand ranged from 50 to over200 wavelengths.The surfacewave catethat roughness in the shadowzone acts to tunnelmore sound into the integralheight was found to be a minimumof 30 and13 wavelengthsfor shadowzone of the partiallyrough surface, relative to the curvedsmooth the upwardand downwardalmospheres, respectively. The CPU time for surface,via a "creepingboundary wave." This wave qualitativelyfollows theGFPE model ranged from 10 to 60 s, dependingon frequency,and was the trendsof both creepingwaves due to diffractionand Tolstoy-type approximately60-1000x fasterthan the two-dimensionalFFP. 3276 d. Acoust.Sec. Am., Vol. 96, No. 5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3276 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 11:00 11:30 3aPAa12. When is downwind propagation really upwind 3aPAa14. Determining the acousticparameters of snow by impulsive propagation? John M. Noble (U.S. Army Res. Lab., Battlefield wavefore inversion. DonaldG. Albert (U.S. Army Cold RegionsRes. EnvironmentDirectorate, White Sands Missile Range, NM 88002) andEng. Lab.,72 LymeRd., Hanover,NH 03755-1290) Fora longtime, atmospheric acoustic propagation has used phases like The amplitudeand waveformshape of atmosphericacoustic pulses "upwindpropagation," "downwind propagation," and "crosswind propa- propagatinghorizontally over a seasonalsnow cover are profoundly gation"to describethe typeof propagationconditions present in the at- changedby theair forcedinto the snow pores as the pulses move over the mosphere.For short-range propagation (<3 kin), theportion of theatmo- surface.Attenborough's four-parameter, rigid-ice-frame porous treatment spherebetween 50 and100 m will primarilyinfluence the propagationof of snowis appliedto theinverse problem, where the observed waveform sound.This regionof the atmosphereis calledthe surfacelayer. Typically, is usedto determinethe acousticparameters of the snow.Horizontally throughthis region there is not muchchange in the meanwind direction. propagatingacoustic pulses were generated using blank pistol shots fired 1 Thereforethe termsmentioned earlier have some meaning for short-range m abovevarious seasonal snow coversand measuredby surfacemicro- propagation.This is dueto theeffective speed of soundfor a givendirec- phones60 m away.Various inversion strategies, both frequency and time tionnot varying much due to thesmall changes in themean wind direction domain,were investigated to determineautomatically the acousticparam- with height.For longerrange propagation, this terminologycould have etersthat accuratelypredict the observedwaveforms. Preliminary results little to do with theactual propagation conditions due to theeffect of wind show that the effectiveflow resistivityand depthof the snow are the speedand wind directionvariations with heightabove the surfacelayer. controllingparameters. [Work supported by the Directorateof Research The purposeof thispresentation is to discusswhy thisterminology is not andDevelopment, U.S. Army Corps of Engineers.] appropriateand for whatconditions it is appropriatefor usein atmospheric acoustics. 11:15 11:45 3aPAa13. Complex image theory for sound propagationabove 3aPAalS. New fast field programsfor a multiple-sourcesystem. Y. ground. MichaelJ. White (U.S.Army Construction Eng. Res. Lab., P.O. L. Li (Dept.of Elect.and Cornput. Eng., Univ. of Illinois,Rm. 332, 3rd Box9005, Champaign, IL 61826-9005)and Y.L. Li (Univ.of Illinois, fl. North CSRL, 1308 W. Main St., Urbana,IL 61801) and Michael J. Urbana, IL 61801) White (U.S. Army ConstructionEng. Res. Lab., Champaign,IL A very simpleand accurate method is introducedfor the computation 61826-9005) of thesound field above an impedanceground or a poroushalf-space. The procedureis basedon compleximage theory. Using Prony's method, the A new fast field program(FFP) hasbeen developed for numerical slowlyvarying part of theintegrand in theSommerfeld integral is approxi- computationof sound pressure from a phasedmultiple-source or multiple- matedby a shortseries in termsof complexexponential functions. Com- receiversystem in a layeredmedium. The new FFP is basedon a far-field biningthe series of exponentialfunctions and the remaining integrand, the approximation.Using the stationary phase method, the twofold integral for resultingintegral can be exactlyevaluated by the Sommerfeldidentity. A soundpressure in thefar field is reduced to a onefoldintegral. The onefold newclosed-form expression of thesound field is representedasthe original integralmakes the newFFP very efficient and more practical than com- source,its quasistatic image, and three "images" with complex amplitudes putationperformed individually for eachsource. A criterionfor validityof andpositions. Avoiding numerical evaluation of the Sommerfeldintegral the far-fieldapproximation is also given. The soundpressure of several makesthese closed-form expressions computationally very efficient.Nu- phased-arraysystems in a layeredmedium has been computed. Numerical merical resultsshow that these closed-formGreen's functionsare very resultsfrom the new FFP arecompared with somewell-known results. The accuratefor thecomputation of the nearand intermediate fields. agreementis excellent. WEDNESDAY MORNING, 30 NOVEMBER 1994 PECOS ROOM, 8:30 TO 11:15 A.M. Session 3aPAb PhysicalAcoustics: Bubble Dynamics and Cavitation Lev A. Ostrovsky,Cochair Instituteof AppliedPhysics, Nizhini Novgorod 603600, Russia Michalakis A. Averkiou, Cochair AppliedPhysics Laboratory, University of Washington,Seattle, Washington 98105 ContributedPapers 8:30 pressureand conductivity on thedielectric breakdown of water.Well de- finedrectangular pulses (80-kV, 3-ns rise time, 100-ns duration) have been 3aPAbl. A nanosecondacoustic source: Experimental investigation appliedto a gap(0.04-0.21 cm), between Rogowski profile electrodes, of pulseddielectric breakdown of water and its dependenceon containingde-ionized, nondistilled water, de-ionized, distilled water, or pressureand conductivity.Hugh M. Jones(Dept. of Phys.and Eng. sodium chloride •olutions (0.001-1.0 M). Breakdown in these liquids has Phys.,:Stevens Inst. of Tcchnol.,Hoboken, INJ 07030) and Erich E. Kunhardt(Stevens Inst. of Technol.,Hoboken, NJ 07030) beenstudied at pressuresup to 400 atto.Calibrated voltage dividers situ- atedon thesource and load sides of thetest gap permitted measurement of Sparkgaps are finding use as underwater acoustic sources insonar and theinterelectrode potential and the current response. From these measure- prospectingapplications. It is thusimportant todetermine the influence of ments,the time lag to breakdown,breakdown voltage, power input to the 3277 J. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3277 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp liquid,and temporal characteristics of the breakdown process have been goodquantitative agreement with predictionsbased upon the multipole determined.The breakdowntime lag increaseswith increasingpressure projectionsof the acousticradiation pressure on the bubble,taking into andgap width, and decreases with increasingfield. Moreover,it is weakly accountthe monopoleacoustic response of the bubble.The monopolc dependenton the conductivityof the liquid.An Ohmiccurrent-voltage responseis limitedby inertiaand radiationdamping for the size rangeof relationhas beenobserved during the prebreakdownstage. A dynamical bubblesconsidered. A simplifiedtheory for theshape (based on the defor- modelhas been developed to explainthese results and is alsopresented at mationresulting from the Bernoulli pressure of incompressiblep?tential thismeeting. [Work supported by ONR.] flowaround a sphere)is generally consistent with the measurements forthe smallerbubbles observed. [Research supported by ONR.] 8:45 9:30 3aPAb2. Processes leading to cavity formation and dielectric breakdown in liquids subjectedto high electric fields. Hugh M. 3aPAbS. Evolution of surface properties of acoustically leviteted Jones(Dept. of Phys.and Eng. Phys., Stevens Inst. of Technol., Hoboken, bubbles in aqueous solutions and seawater and sources of NJ 07030) and Erich E. Kunhardt (StevensInst. of Technol.,Hoboken, anomalousdamping. Thomas j. Asakiand PhilipL. Marston N1 07030) (WashingtonState Univ., Pullman, WA 99164-2814) The useof liquid-filledgaps as aeonsticsources requires an under- The complexfree-decay frequency was measuredfor quadrupoleos- standingof the contributionsfrom variousmicroscopic processes to the cillationsof acousticallylevirated bubbles. Single bubbleswere stably dynamicsof currentgrowth, cavity formation, and dielectric breakdown. A leviratedfor periodsof up to 3 h. During this time the naturalfrequency modelis presentedfor the developmentof cavitiesand dielectricbreak- and dampingwere measuredat approximately2-mix intervals.Bubble down in liquidssubjected to uniformhigh amplitudeelectric fields with oscillationswere detectedby meansof an opticalextinction technique. durationsof microsecondsor less.In this model,breakdown proceeds in Each free-decayrecord was takenby abruptlyterminating the amplitude four stages:formation of a nucleationsite in the liquid near an electrode, modulationused to induceshape oscillations. The methodis remarkably growthand expansionof this site until the local densityis reducedsuffi- sensitiveto the presenceof impuritieswhich adsorb onto the surfacefrom cientlyfor electron-impactionization to occur,growth of an electronava- solution.Damping associated with "dean" smallbubbles agrees with pre- lancheand its transformationinto an ionizingfront, and propagation of the dictionsassociated with viscousand boundarylayer considerationsfor frontvia a sequenceof processesoccurring in the regionahead of thefront, oscillationsabout a sphericalshape. The complexfrequency obtained for namely,heating by electroninjection, lowering of the liquid density,and controlledbulk concentrations of surfactant (Triton X-100) agreesquali- avalanchegrowth and retardation.Expressions for the durationof eachof tativelywith planarsurface capillary-wave studies. Salt water solutions thesestages are derived and their behavior with pressureand field strength andPuget Sound seawater are also 'examined. Anomalous additional damp- analyzed.From this, a critical energycriterion for breakdownis obtained. ing was foundin associationwith largerbubbles (radius •>750/am) and Comparisonis madewith experimentalresults for water,salt solutions, and possiblesources will be considered.[Research supported by ONR.] the liquid noblegases, and for pulsedurations in the microsecondand submicrosecondtime scales.[Work supported by ONR.] 9:45 3aPAb6. Phase locking of nonlinear monopoleswith reactive 9:00 coupling.Svefiana Fdman, Yuri KobeIcy, Lev Ostrovsky,a) and Irina 3aPAb3. An experimental investigationof bubble shapes from a Soustova(Inst. of Appl.Phys., Nizhni Novgorod, Russia) nozzlein water. B.K. Choiand S. W. Yoon (Dept.of Phys.,Sung Kyun Recentlyit was shownthat a systemof couplednonlinear acoustic KwanUniv., Suwon440-746, Republic of Korea) oscillatorssuch as bubblesin a liquidmay generatea coherentradiation The shapeoscillations of bubblesfrom a nozzle in water have been startingfrom the initially incoherentstate. However, such an active (ra- well investigatedby Longuet-Higgins[M. S. Longuet-Higgins,J. Fluid diative)coupling is typicallyweak, especially if thesize of thesystem is Mech.201, 543-565 (1989)].In thepresent paper the ellipticaldeforma- smallerthan the acousticwavelength. Here a stronger,reactive coupling, tiondue to a bubblerising in wateris introducedin theLonguet-Higgin's suchas an interactionof bubblesvia the potentialfluid motionaround theory.The bubbleshape oscillations in water are also experimentally them,is considered.It is shownthat an initialincoherent phase distribution observedusing a stroboscopephotographic technique. The theorywith an is unstableonly for theexcitation level exceeding a definitethreshold. For elliptical deformationcondition well describesthe experimentalobserva- a nonlinearstage of generationa three-modeanalytical model is used, tion of bubble shapeoscillations. The dependenceof antipoletime on permittingone to performa phase-planeinvestigation of a systemand to bubbleradius shows good agreementbetween the theoreticalestimation estimatethe amplitude and duration of thegenerated coherent pulse. From andthe experimentalobservation. [Work supported by the KoreaScience theviewpoint of nonlineardynamics, such an effectis an example9f a andEngineering Foundation.] "chaos-order"transition in a Hamiltoninnsystem (although chaos may be justa lackof coherence).The roleof smalldissipation is alsoconsidered. Someestimates are made for the ensemble ofbubbles in a liquid.a)Now at Univ.of Coloradoat Boulder,CIRES, ET[dERIJNOAA, 325 Broadway, 9:15 R/E/ET, Boulder, CO 80303. 3aPAb4. Radiation force, equilibrium position, and shape for acoustically levitated bubbles driven above resonance. Thomas J. 10;00-10:15 Break Asat0 and Phfiip L. Marston (Phys. Dept., WashingtonState Univ., Pullman,WA 99164-2814) The equilibriumpositions and shapes of stablylevitated bubbles on the 10:15 Earth in an ultrasonicstanding wave havebeen measured and calculated 3aPAb7. Mass diffusion in spark-'nducedvapor bubbles. J.S. for bubbleslarger than resonance size (radius•140/am). The methodof Allen, M. A. Averkiou,L. A. Crum (Appl. Phys. Lab., Univ. of levitatingbubbles typically having radii >400 pan was previouslyde- Washington,Seattle, WA 98105), C. M. Young,and G. R. Hess (Tetra scribedIT. J.Asaki, P. L. Marston,and E. H. Trinh,J. Acoust. SOC. Am. 93, Corp.,Albuquerque, NM 87109-4512) 706-713 (1993)].The equilibriumposition gives a measureof the radia- tion forceon the bubble.Trapped bubbles exhibit an oblateshape of pri- The diffusionof gasinto a spark-generatedvapor bubble is shownto be marily quadrupoledistortion. They are positionednear to and abovethe an importantfactor when attempting to generaterepeated oscffiations of axial pressure minimum in the levitation chamber. These results are in the bubble.Predictions for the radius-timecurve based on the Trilling 3278 J. Acoust.Soc. Am., Vol. 96, No.5, Pt.2, November1994 128thMeeting: Acoustical Society of America 3278 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp equationare matched with experimental measurements and the equilibrium 10:45 radiusis deduced.The effectof theambient, hydrostatic, and vapor pres- suresof theliquid on thebubble collapse time is demonstrated.The high- 3aPAb9.Acoustic microstreaming within a gas-filledbubble. Wesley frequencyapproximation of the first-ordersolution Of the Eller-Flynn L. Nyborg (Dept.of Phys.,Univ. of Vermont,Burlington, VT 05405) formulationfor massdiffusion is utilizedto estimatethe amountof gas Whensurface waves occur on the boundaryof a gas-filledspace sur- diffusedinto the bubbleat the end of a singlecycle. An increasein the roundedby liquid,the resultingmotions of the gasinclude velocity com- bubbleradius and collapse time is notedand this process is repeatedfor an ponentsparallel to thegas-liquid interface. Because these satisfy a nearly extendednumber of cycles.The frequencysignature of the resulting nonslipcondition, boundary layers are established and small-scale acoustic bubbleoscillation is analyzed.The increasein the bubbleradius and the streamingis generatedin the gasphase. Approximate theory suggests that periodof oscillationdue to diffusion,and the gas-microbubbleresidues significantconvection can occur, and may play a rolein sonicenhancement remainingafter collapse, have potentially important effects when generat- of rate processeswhich occurat gas-liquid interfaces.For example,in- ing a repeatedsequence of vaporbubbles, as in extracorporealshock wave trabubblestreaming may contributeto the enhancementof rectifieddiffu- lithotripsy.[Work supported in partby the U.S. Navy andthe National sionobserved by Gould[J. Acoust.Soc. Am. 56, 1740-1746 (1974)]. Instituteof Health.] 10:30 11:00 3aPAb8.Acoustic modeling of plasma-inducedvapor bubbles. Gary 3aPAb10.A model for cavitation damage during ultrasonic cleaning. R. Hess,Arturo E. Rodriguez,Niels K. Winsor,Chris M. Young (Tetra QuanQi, JohnG. Harris,and RobertE. Johnson(Dept. of Theor.and Corp.,Albuquerque, NM 87109-4512), LawrenceA. Crum (Univ. of Appl. Mech., Univ. of Illinoisat Urbana-Champaign,216 TalbotLab., 104 Washington,Seattle, WA 98105), and RobertF. Stellingwerf (Los S. WrightSt., Urbana,[L 61801) Alamos Natl. Lab., Los Alamos, NM 87544) A modelis proposedin thisreport to describethe potentialgrowth of Plasma-inducedbubbles respond to time-dependentinjection of energy an existingcrack in thestructural component caused by collapsingbubbles which modifiesthe acousticoutput relative to "classical"gas bubbles. duringultrasonic cleaning. A local pressurerise is generatedby the col- Additionally,they consistprimarily of hot vapor which complicatesthe lapseof a singlebubble and the momentumof thecollapse is describedby thermodynamics,elevates the importanceof sometraditionally untreated the Kelvin impulsel(t). By assuminga uniformpressure distribution and variables,and requiresadditional physical process treatments beyond the usingdynamic fracture mechanics, we obtain a simple relationthat ex- basic hydrodynamics.A code that is based upon fundamentalphysical pressesthe dynamicstress intensity factor K(t) as a functionof the Kelvin principleswas developedto study the importanceof many of thesevari- impulse.Further simplification is achievedby assumingspherical bubble ables.The codeis capableof treatingthe actualdriving circuit, resultant deformationin the descriptionof the Kelvin impulse,as suggestedby plasmabehavior, transition from cylindricalto sphericalgeometry early in Blakeand Gibson[Ann. Rev. Fluid Mech. 19, 99-123 (1987)], and this the discharge,radiation production, plasma chemistry, thermal transport, leadsto a relationbetween the dynamicsof a singlebubble and the stress and hydrodynamicsin a modifiedFlynn formulation.Primary output con- intensityfactor K(t). The time historyof K(t) is discussedfor a com- sistsof bubblewall acceleration,radius, etc., energy balance, and far field pletelycollapsed bubble obeying the Rayleigh equation. Once the dynami- pressure.The codehas been validated with experimentaldata and will be cal stressintensity factor exceedsthe fracturetoughness Ktc crack will comparedwith ongoinghydrocode model developmentas well. Experi- startto grow.Repeated action of collapsingbubbles eventually leads to the mentaland theoretical results are presented for largevapor bubbles. [Work failureof thecomponent. [Work supported by theManufacturing Research supportedby theU.S. Navy.] Centerof theUniversity of Illinois.] 3279 d. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128th Meeting:Acoustical Society of America 3279 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp WEDNESDAY MORNING, 30 NOVEMBER 1994 TRINITY B, 8:00 A.M. TO 12:00 NOON Session 3aPP Psychologicaland PhysiologicalAcoustics: Posters on Hearing (Poster Session) CraigA. Champlin,Chair CommunicationDisorders, University of Texas,Attotin, Texas 78712 ContributedPapers All posterswill be on displayfrom 8:00 a.m.to 12:00noon. To allowcontribulors an opportunityto seeother posters, contributors of odd-numberedpapers will be at theirposters from 8:00 to 10:00a.m., and contributors of even-numberedpapera will be at theirposters from 10:00 a.m. to 12:00 noon.Posters will remainon displayuntil 5:00 p.m. 3aPPI. Forward-masked intensity increment thresholds at two The total perceptionfor pitch and loudnessas a functionof level recoverytimes. LanceNizami and Bruce A. Schnbider(Dept. of differencebetween the leading and trailing stimuli is investigatedusing the Psychol.,Erindale College, Univ. of Toronto, 3359 MississaugaRd., samestimulus configuration and measuringthe paradigmwhich clearly Mississauga,ON L5L 1C6, Canada) showedthat the dominanceof the leadingstimulus depends on the level difference[S. Aoki andT. Houtgast,Hear. Res. (1992)]. A briefstimulus of Forward-maskedjust-noticeable differences were obtainedfrom two 20 ms is subdividedinto two partswith durationsT• and Tz. Each part listenersusing a two-intervalforced-choice procedure. 'Inone of theinter- consistsof a sinusoidalsignal of either1 or 2 kHz for pitchperception, or vats,a 2-kHz, 200-msmasker preceded a 2-kHz Gaussian-shapedtone pip eachpart consists of a 2-kItz sinusoidalsignal with either+ or -3 dB for ((r=0.5 ms).The otherinterval contained the samemasker followed by a loudnessperception. The measuringparadigm aims at assessingthe critical ratioTilt 2 for whichboth parts contribute equally to the overallsensation comparisontone pip. The listener'stask was to identifythe intervalcon- of pitchor loudnessfor thesebrief stimuli.!n contrastto the earlierstudy tainingthe loudertone pip. Within a block of trails both maskerintensity on dieboriccues, the effect of thelevel differencebetween the leading and (range=10-80 dB SPL) andmasker-target time gap(3 or 80 ms)were trailingstimuli on pitchperception is foundto be smallerand discontinu- keptconstant. The intensity of thestandard tone pip (beforemultiplication ous.The effecton loudnessperception is foundto be greaterand sym- by the Gaussianenvelope) was always set to 20 dB abovethe levelof the metrical.It is alsofound that the characteristic curves of theseperceptions masker.When intensity-increment thresholds are plottedas a functionof forma meaningfultriangular area. maskerlevel at bothtime gaps, thresholds rise to a maximumat a masker level of 50 dB SPL beforedeclining again. This patternmay be consistent 3aPP4. A computationalmodel of auditory localization. Keith D. with the ideaof two intensity-processingchannels, one for loudersounds Martin (The MediaLab., MIT, 20 AmesSt., Rm. E15-401,Cambridge, andone for softerones [see E-G. Zeng,C. W. Turner,and E. M. Relkin, MA 02139) Hear.Res. 55, 223-230 (1991)].[Work supported by NSERC.] A novel computationalmodel of localizationhas beenimplemented. 3aPP2. Abstract withdrawn. Using a simplifiedmodel of the cochleafilter bank, maximum-likelihood estimatesof azimuthand elevation are formed from interauralintensity and phasedifferences at energyonsets in multiplecritical bands. Preliminary resultsshow that the modelis capableof resolvingfront/back confusions and otherelevation ambiguities resulting from the "conesof confusion." Theonset sampling strategy is intended to modelpsychoacoustic phenom- ena such as the precedenceeffect and allows the model to deal with multiplesound sources and reverbcrankenvironments. Examples of the model'sability to resolveambiguous signals will be presentedand com- paredwith humanperformance. [Work supported by NSE] 3aPP5. Efferent adaptation and fatigue: The effect of contralateral noise on spontaneousotoacoustic emissions. GregoryL. Dykstra (Dept.of Phychol.,Mczes Hall 330, Univ.of Texas,Austin, TX 78712) Mort et al. [Hear.Res. 38, 229-242 (1989)] haveshown that both frequencyand amplitudeof spontaneousotoacoustic emissions (SOAEs) can be modulatedby contralateralacoustic stimulation. They alsoexam- inedthe effects of stimulusdurations up to 4 mir in searchof long-term adaptation,but nonewas found.Because the drivenrate of efferentfibers declinesby Onlyabout one spike per second per minute [M. C. Liberman andM. C. Brown,Hear. Res. 24, 17-36 (1986}],longer durations might be necessaryto observeefferent adaptation/fatigue. In the presentstudy, 3aPP3. Effect of the level difference between leading and trailing SOAEs of threesubjects were measuredin the presenceof contralateral stimuli on pitch, loudness,and binaural perception. ShigeakiAoki narrow-bandnoises with variousfrequency characteristics and with dura- (N-'IT HumanInterface Labs.; 1-2356, Take Yokosuka-shi, Kanagawa tionsof up to 60 min. The hypothesizedeffect---an initial declinein 238-03,Japan) and' Tamtoo Houtgast (TNO Inst. for HumanFactors, SOAEsamplitude under contralateral stimulation followed by a returnto Soesterberg,The Netherlands) preexposurelevels with the onsetof efferentadaptation--was not consis- 3280 d.Acoust. Soc. Am., Vol. 96, No.5, Pt.2, November1994 128thMeeting: Acoustical Society of America 3280 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp tentlyobserved. While seen in somesessions for somesubjects, it could for genetichypersomnia (11-13 yr old:IQ>120; meds:15-20 mgmeth- not be broughtunder experimental control. Thus theseresults were in ylphenidate,'r=2 h), resteduntreated performance over 4-min periods in approximateagreement with the findingsof Mott et al. Somemethod- 24-rainintervals changed -100-fold (fromnormal to periodswith wide ologicaland functional implications of thesefindings will be discussed. transitions).At 10-12 min followingdissolution of single,sublingual [Worksupported by a NIDCDgrant to D. McFadden.] 10-mgdoses, transitions narrowed and performance began to improve(re: normalcomposite). Performance continued to improvefor 10-15 min, 3aPP6. Processing of nonlinguistic auditory stimuli in thenremained relatively consistent (in somecases within normal limits for Landau-Kieffner Syndrome: A case study. Clifton Kussmaul, 40-50 min).Performance returned to untreatedlevels in an orderlyfash- KathleenBaynes (Ctr. for Neurosci.,Univ. of California,Davis, CA ion:Well-defined transition areas gradually widened, then spread toward 95616),and Judy Kcgl (RutgersUniv., Newark, NJ 07102) extremes.Under similar conditions subsequent dose-response functions for "Acquired aphasiawith convulsivedisorder" or Landau-Kleffner an individualdiffered little. Name brand and generic preparations appar- Syndrome(LKS) wasfirst describedin 1957 [W. M. Landauand F. R. entlydissolve at differentrates; some differences among individuals may Kleffner,Neurology 7, 523-530(1957)]. This language disorder typically reflectvariations in excipientsor compounding. manifestsas a declinein verbalexpression and comprehension in children 3aPP9. The effect of a diver's glove on vibrotactile thresholds. whohad been developing normally. EEG is alwaysabnormal, although JeffreyD. Travisand Joan Schoppe (Appl. Res. Labs., The Univ. of Texas clinicalseizures are not always observed. This report presents a 26-yr-old at Austin,P.O. Box 8029, Austin,TX 78713-8029) right-handedfemale who was diagnosed with LKS at age4 with an ab- normalEEG and seizure activity. Her EEG,MRI, andaudiogram are now An experimentmeasuring vibrotactile thresholds in humansubjects normal,but PET demonstratesbilateral temporal lobe hypometabolism. A was performed.Vibration thresholds at frequenciesbetween 100 and400 detailedlinguistic comparison of herlimited spoken English and relatively Hz undernormal conditions were compared with otherresearchers' pub- goodsigned English is reportedelsewhere [K. Baynoset al., lnt.Neurop- lishedresults. To examinehow diving gear would affect a sea diver's sychol.Soc. (submitted)]. Interestingly, she listens to andenjoys several vibratorysensitivity, vibrotactile thresholds were determined on themiddle typesof music.This discrepancymotivates our initialinvestigation of her phalanxof subjectswith andwithout diver's gloves. Two kindsof diver's abilityto performnonlinguistic auditory tasks. Despite easy recognition of gloveswere tested,one designedfor cold water and the otherfor warm environmentalsounds, discrimination thresholds of pitchand rhythm are water. It was establishedthat diver's glovesdo have an effect on vibro- greatlyexaggerated. Such data can clarify which brain processes are spe- tactilethresholds, and that the specifictype of glove(cold water or warm cificto language,and which correspond to moregeneral auditory or hier- water)alters the normal shape of thethreshold curves in differentways. archicalprocessing. [Work supported by NIH.] 3aPP10.Personal sound. W. F. Druyvesteynand R. M. Aarts (Philips 3aPP7. Spontaneousremediation of sensorineuralhearing lossin an Res. Labs., Bldg. WAK, P.O. Box 80000, 5600 JA Eindhoven,The infantgirl. RichardP. Meier (Depts.of Linguist.and Psychol., Univ. of Netherlands) Texas,Austin, TX 78712), Ren6eA. E. Zakia,and Craig A. Champlin (Univ. of Texas,Austin, 'IX 78712) Introducingmore audio/video equipment (CD, DCC, TV, CD-I, etc.) into a roomcreates a new audioproblem, one of multiplesound sources An infantgirl (JD) wasassessed as havinga mild-to-moderatesenso- with multiplelisteners. When differentpersons, denoted as A, B, C, etc., rineuralhearing loss in herleft ear anda moderate-to-severesensorineural listento differentprograms, denoted as "a," "b," "c," personA experi- lossin her rightear, basedon resultsof auditorybrain-stem response encesprogram "a" as soundand programs"b" and "c" as noise.Each (ABR)at age 3 monthsand soundfield testing at 4, 5, and9 months(Better personwould prefer a highsound/noise (SfN) ratio at hislistening position. earPTA=55 dB HL). JD wasfitted with hearing aids binaurally. The one In thiscontribution the situationof two personsworking with their(mul- risk factorin her birthhistory is prenatalpolydrug exposure, including timedia)PCs in an office,or watchingin a livingroom two TVs with cocaine.She had recurrent otitis media, but tympanometryand otherevi- accompanyingsound, is considered.In order to obtaina specification, denceweigh against middle ear problemsas the causeof her hearingloss. listeningtests were done, which gave a desiredS/N ratio of about 20 A follow-upABR at 13 monthsrevealed JD to have normalhearing, a dB(B). In an anechoicenvironment such a specificationis easilyrealized resultconfirmed by audiometrictesting of her unaidedheating thresholds usinga loudspeakerarray to controlthe directivity.In a real (living)room (PTA= 10 dB HL). Theimplication is that,between ages 9 and13 months, this is not sufficientand active noisecontrol (to decreaseN) and active JD's hearingimproved to normal levels,possibly as a resultof delayed soundcontrol (to increaseS) are used,particularly in the low-frequency maturationof theperipheral auditory tracts. Early detection of hearingloss region.During the presentationat the conference,recordings will be re- mayreveal more children like JD whohave sensorineural losses that spon- producedof realizedS/N ratiosof 34 dB(B) in the anechoicroom and of taneouslyremediate with development.Such cases would highlightthe morethan 20 dB(B) in a living room. needfor repeatedtesting of unaidedthresholds in hearing-impairedinfants, especiallyif aggressiveintervention is contemplated.[Work supported by 3aPPll. Multisensoryinteraction: Influence of spatial visual cueson NIH andthe Texas Advanced Research Program.] auditorydetection. DietrichPafiitz (GraduateCollege Psychoacoust., FB 8, OldenburgUniv., D-26111 Oldenburg, Germany) 3aPP8. Acousticevaluation of pharmacodynamics.D. B. Daly and D. M. Daly (Box 210855,Dallas, TX 75211) Recentphysiological and psychologicalstudies suggest spatiotopic mapsof auditoryspace often build up by groupsof multisensoryneurons. Ability to classifysets of certainsynthetic sounds fluctuates with vigi- At thisneuronal level stimulusrepresentations of differentmodalities seem lance.In patientswith genetichypersomnia, performance can fluctuate to be transformedinto a commoncoordinate system. A multimodalstimu- from well-defined classes with narrow transitions to intervals with wide lus may produceenhancement, depression, or no interactioneffect on the transitionswhere only stimuli at extremesare identified consistently. LRCs cell activity,depending on its certainspatiotcmporal combination. In sev- wereused to measurewhether performance differed from chanceand if so, eral experimentsthe influenceof visual cueson auditoryperception was whetherit differedfrom a compositeof normals[Daly et al., J. Neuro- examined.The resultsindicate a dependenceon spatialand temporalpa- physiol.44, 200-222(1980)]. In a groupof subjectsindependently treated rameters.[Work supported by DFG.] 3281 d. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128th Meeting:Acoustical Society of America 3281 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp WEDNESDAY MORNING, 30 NOVEMBER 1994 TRINITY A, 8:00 A.M. TO 12:00 P.M. Session 3aSP SpeechCommunication: Vowel Productionand Perception(Poster Session) Linda Thibodeau, Chair Departmentof SpeechCommunication, Jones Communication Complex, University of Texas,Austin, Texas 78712 ContributedPapers All posterswill be on displayfrom 8:00 a.m. to 12:00noon. To allow contributorsan opportunityto seeother posters, contributors of odd-numberedpapers will be at theirposters from 8:00 to 10:00a.m., and contributors of even-numberedpapers will be at theirposters from 10:00 a.m. to 12:00 noon.Posters will remainon displayuntil 10:00 p.m. 3aSP1. Extending the perceptual magnet effect to a CVC word UCLA, 405 Hilgard Ave., Los Angeles, CA 90024-1543 and Inst. de context. RichardEyraud and PatriciaK. Kuhl (Dept. of Speechand Phon&.CNRS URA1027, Paris,France) Hear. Sci., WJ-10, Univ. of Washington,Seattle, WA 98195) In French, the acousticeffects of anticipationof a final high front Recentresearch by Kuhl and her colleagueshas demonstrateda per- roundedvowel, [y], canbe observedin a preceding[i]. Thislabial antici- ceptualmagnet effect in vowelsand consonants suggesting that perceptual pationinduces a loweringof the formantsbeing measured (F2,F3,F4) organizationis stronglyinfluenced by categorygoodness. Equidistant bothin the middleand, to a greaterextent, at the endof the [i] in [iCoy] stimuli clusteraround the best exemplarsof a category,demonstrating sequences.Although significant, this contextual influence does not jeopar- poorerdiscriminability and decreasedperceptual distances. Conversely, dizethe acoustic contrast between [i] and[y]. To understandthe articula- regionssurrounding the worstexemplars of a categoryare "stretched," tory basisof theseresults, acoustic consequences of the gesturesinvolved demonstratingrelatively better discriminability and increasedperceptual in the so-calledrounding contrast between [i] and[y] are investigated distances.The presentexperiments extend this finding to a wordcontext by througharticulatory modeling. An [i]-like areafunction is simulatedwith investigatingthe perceptual organization of theAmerican English vowel/i/ differentdegrees and combinationsof anticipatorylip protrusion,reduc- in isolationand in a CVC word context,specifically /bid/. In the vowel tionof the area at the lips,and larynx lowering. [i] allowslittle variation experiment,eight variants of/i/were synthesizedby independentlychang- in lip gestures;beyond a limitedrange of coarticulation[i] shiftsacousti- ing F1 and F2. Similarly,in the CVC word experiment,eight variantsof callyto theregion occupied by [y]. While[i] appearsto be quantalwhen the word /bid/ were synthesizedby independentlychanging the vowel we considervariation in tongueconstriction, it showsa sensitiveresponse steadystates of F1 and F2. Adult monolingualspeakers were askedto to lip perturbation.In the [iCy] sequencesobserved, it seemsthat con- judgethe goodnessof eachvariant and the similarityof pairedtokens on straintson distinctivehessprevent a greaterlabial anticipation. a seven-pointscale. Multidimensionalscaling analyses demonstrated a 3aSP4. Effects of lexical status on native and non-native similarperceptual magnet effect in boththe vowel and CVC wordexperi- ments.These resultssuggest that the perceptualmagnet effect observed English-speakingadults' vowel perception. Victoria L. Michela, with phoneticunits extends to the lexicallevel, possiblycontributing to LaurenA. Randazza,Amanda C. Walley (Dept. of Psychol.,Univ. of lexicalaccess. [Work supported by NIH.] Alabamaat Birmingham,Birmingham, AL 35294),and JamesE. Flege (UA•) 3aSP2. Effect of voicequality on the tense/laxdistinction for English vowels. Lori L. Holt, AndrewJ. Lotto,and Keith R. Kluender (Dept.of Monolingual,English-speaking adults and nativeChinese (Mandarin) Psychol.,Univ. of Wisconsin,Madison, WI 53706) speakerswho learned English as a secondlanguage heard stimuli from two "native,"synthetic continua, in whichthe vowels ranged from English/•/ For a varietyof Eastand West African languages, voice quality cova- to/i/in the context/b_b/or/b_p/. Thusthe endpoints of the firstcon- ties with tongueroot advancement.In thesevowel systems,an advanced tinuumconstituted an Englishword and a nonword("bib" vs *"beeb"); tongueroot vowel is producedwith breathyphonation, whereas, a modal the reverseheld for the secondcontinuum (*"hip" vs "beep").These voicequality is usedwith nonadvancedtongue root. A potentialexplana- samesubjects also heard stimuli from two "foreign"continua, where the tionfor thisregularity, based on theinteraction between acoustic effects of vowelsranged from English/# to a foreign(non-English) vowel/Y/in the vocal-tractshape and of voicequality, was evaluated. Because it hasbeen contextsdescribed above. Thus the end pointsof the firstcontinuum cor- suggestedthat the advancedtongue root contrast is similarto the tense/lax respondedto a wordand a nonword("bib" vs *"bYb"); bothend points contrastin English,male and female series varying perceptually from tense of thesecond continuum corresponded to nonwords (*"hip" vs *"bYp"). to lax were synthesizedfor severalEnglish vowels. Breathy versions of After trainingon end points,subjects' identifications of the nine stimuliof each series were created by increasingspectral tilt. Results from identifi- a givencontinuum were examinedto assesswhether: the Chinesespeakers, cationtasks indicated that, in general,breathy phonation led to morehigh like nativeEnglish speakers, exhibit a "lexicalbias" effectfor English vowels being identifiedas tense.In addition,the effect of breathinesswas vowels(from the nativecontinua); vowel categories not bounded by an- greaterfor vowelsmodeled after female productions. These results suggest othernative/English vowel (as in theforeign continua) expand outward or thatthe covariationin Africanlanguages may be consistentwith the gen- becomebetter defined with increasedexposure to Englishand/or lexical eral principleof auditoryenhancement and adaptive dispersion. The find- status.[Work supported by NIH.] ingsmay alsobe relevantto genderdifferences in voicequality. [Work supportedby NIDCD Grant No. DC-00719 and NSF Grant No. DBS- 3aSP5.Learning to perceiveand produceAmerican English vowels: 9258482.] A studyof speakersof BrazilianPortuguese. MarialiceSzpigel (Dept. Speech,Commun. Sci., and Theatre,St. John'sUniv., 8000 Utopia 3aSP3.Limitation on labial anticipationin [i] in a languagewith an Parkway,Jamaica, NY 11439) and FrederickaBell-Berti (St. John's [i]-[y] contrast. C6cileFougeron (Phon. Lab., Dept. of Linguist., Univ., Jamaica,NY 11439 and HaskinsLabs., New Haven,CT 06511) 3282 J. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3282 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp Brazilianswho are fluent in Englishhave more difficulty perceiving formantstimuli was stronglyinfluenced by botha formant/harmonicin- andproducing American English vowels than consonants. This study ex- teractionand F•-F o Barkdistance. No evidencefor a peakin discrim- aminesvowel perception and production by tennative speakers of Brazil- inabilitynear F•-F0=3.0-3.5 Bark was observed,however. The current ianPortuguese who had begun the sixth year of studyof American English studyextended these findings to stimulimore characteristic of female (at the InstitutoBrasiI-Estados Unidos, Rio de Janeiro,Brazil). At this talkers.Listeners performed a formantdiscrimination task on one of five level,all studentsare ableto speakEnglish fluently, but with varying seriesof four-formantstimuli varying in F• -F 0 distance.F 1 ranged from degreesof proficiency;within the program constraints, the subjects were 3.2 to 7.7 Bark withina series,and F 0 from 1.75 to 2.75 Bark between chosento representdifferent levels of Englishproficiency. These bilin- series.Preliminary results confirm both the strengthof the formant/ guals'perception of AmericanEnglish vowels (produced by nativespeak- harmonicinteraction and the lack of a peak in discriminabilityat ersof AmericanEnglish) will be comparedto thereported perception of F•-F0=3.0-3.5 Bark.Results also point up theneed for a moreadequate AmericanEnglish vowels [G. Peterson and H. Barney,J.Acoust. Soc. Am. characterizationof how formant frequency is representedin the auditory 39, 151-184(1952)]. The bilinguals' productions of 15 American English system.[Work supported by NIDCD.] vowelswere identified by six teachersof English(three native Americans andthree native Brazilians), with extensiveexperience teaching English. 3aSP9.The perceptionof vowelheight in CastilianSpanish: Effects Ability to perceivethe AmericanEnglish vowels will be relatedto pro- of varyingF•- F 0 Bark distance. RichardP. Fahey (Dept.of Psychol., ductionability, for thegroup and for thetwo best and two poorest students. Univ. of Texas, Austin, TX 78712) and Luis E. Lopez-Bascuas [Worksupported by St. John'sUniversity and by NIH GrantNo. DC- (UniversidadComplutense de Madrid,8223, Madrid, Spain) 00121 to the HaskinsLaboratories.] AnalyzingAmerican English vowels, Syrdal and Gopal[J. Acoust. 3aSP6.Baseline acoustic parameters for nasalizedvowels in English Soc.Am. 79, 1086-1100]found that Fi-F o Barkdistance was highly andFrench. MarilynY. Chen (Res.Lab. of Electron.and Dept. of Elec. correlatedwith vowelheight. The [_+high]distinction could be basedon a Eng.and Comput.Sci., MIT, Rm. 36-511, Cambridge,MA 02139) boundaryat 3-3.5 Bark F• -F 0 distance.This correspondsto the distance underwhich the center of gravityeffect is thoughtto occur[Chistovich and Acousticanalysis of nasalizedvowels in the frequencydomain indi- Lublinskaya,Hear. Res. 1, 185-195]. Sincea featuredistinction with an catesthe presenceof extrapeaks, one between the firsttwo formantswith auditorybasis is a goodcandidate for a phoneticuniversal, one would amplitudeP1 and one belowthe first formantwith amplitudeP0; the expectthe [+high] boundary tobe at 3-3.5 BarkF•- F 0 distancein many first-formantamplitude A 1 is alsoreduced relative to its amplitudefor a languages.This is trueof the[-+high] distinction inAmerican English, for nonnasalvowel. These acoustic characteristics may be explainedby speech bothfront vowels [Hoemeke and Diehl, J. Acoust.Soc. Am. 93, 2422(A) productiontheory. The objectiveof thisstudy is to determinethe base line (1993)]and back vowels [Fahey, J. Acoust. Soc. Am. 95, 2978(A)(1994)]. valuesfor the acousticparameters in quantifyingnasality. A1-P1 and In the currentstudy, native Castilian Spanish speakers identified synthetic A l-P0 weretested as measuresof nasalityby comparingvowels adjacent vowelheight series ranging between/i/and/e/or/u/and/o/. Withineach to nasalconsonants and those adjacent to stopsfor Englishspeakers. For set, F o and formantpattern varied orthogonally. Data were analyzedto highvowels, A l-P1 is a betterparameter to distinguishnasal vowels from determine(1) whetherF 1-F 0 distanceis a correlateof perceivedvowel non-nasalvowels, with an averagedifference of 10 dB; however,A 1-P0 is height,and (2) whetherthe [_+high] boundary is at 3-3.5 BarkF1-F o betterfor low vowels,with an averagedifference of 7 dB. Frenchnasal distance. vowelsadjacent to stopswere also examined. To furthertest these param- etersas measuresof nasality,they were systematicallymanipulated in 3aSP10. The effect of removingthe fundamentalcomponent on the syntheticspeech and presented in perceptualexperiments. High correlation perceptionof vowel height in stimuli with varying F 0. Randy L. wasobtained between nasality perception and normalized acoustic param- Diehl andRichard P. Fahey (Dept.of Psychol.,Univ. of Texas,Austin, eters.[Work supported by NSF,NIH, andLeBel fellowship.] TX 78712) 3aSP7. Dialect differences in vowel production and perception. Using front vowels,Hoemeke and Diehl [J. Acoust.Soc. Am. 93, Alice Faber (HaskinsLabs., 270 Crown St., New Haven, CT 06511), 2422(A) (1993)] foundthat F•-F o Bark distanceis a correlateof per- CatherineT. Best (WesleyanUniv., Middletown,CT 06459 andHaskins ceived vowel height. This finding is consistentwith a suggestionthat Labs.,New Haven, CT 06511), and MariannaDi Paolo (Univ. of Utah, perceivedvowel quality dependson the patternof the neural"place" Salt Lake City, UT 84112) representation,rather than the absolute position of spectralpeaks [Potter andSteinberg, J. Acoust.Soc. Am. 22, 807-820 (1950)].On thisview, Earlierwork [Faberet al., J. Acoust.Soc. Am. 94, 1865 (1994)] re- vowelperception should be disruptedif a criticalcomponent of theplace porteddifferences among American-English-speaking listeners from Utah patternis removed.In the currentstudy, listeners identified synthetic vow- andConnecticut/NY in perceptionof the HEEL-HILL andPOOL-PULL els varyingbetween A/and/e/, with F 0 variedorthogonally, in threecon- contrasts(pairs that are nearly merged in Utahbut distinct in thenortheast ditions:in quiet,in quietwith the fundamental component removed, and in US), measuredby threetasks, labeling, AXB discrimination,and keyword low-passnoise with the fundamentalcomponent removed. The resultsre- identification.On thesetasks, a few CT/NY listeners(those with parents portedby Hoemekeand Diehi were replicatedin all three conditions: fromthe southern US) performeddifferently from the other subjects. Their IncreasingF 0 shiftedthe phonemeboundary towards the/œ/end point. vowel spacesalso were qualitativelydifferent from thoseof the other Therewas no apparentdecrease in the size of this effect in the conditions listeners,based on acousticanalysis of threereadings of the keywords.The where the fundamentalcomponent was absent.Thus the role of F 0 in CT/southernlisteners had more high backcrowding and did betteron Utah vowel height perceptionis not as a formantlikepeak in the place repre- POOL/PULL than the other listeners,while the Utah listenershad more sentationof thespectrum. [Work supported by NIDCD.] high front crowdingand did better on Utah HEEL/HILL. These results accordwith theliterature reviewed by Bradlow[Cross-Linguistic Study of 3aSPll. Priming and the enhancement of concurrent vowels. D.D. Paschall (The Univ. of Texas at Dallas, P.O. Box 830688, GR4.1, VowelInventories, Cornell (1993)] relatinglisteners' ability to discern Richardson,TX 75083-0688) small vowel differencesto the numberof vowels in their language,but were tentativebecause of the small numberof CT/southernsubjects. The Experimentswere conductedto determinewhether listeners with nor- currentstudy presentsperception and productiondata from additional mal hearingcan exploitinformation in a priorsample of speechto segre- Connecticut/NYsubjects confirming the original finding. [Work supported gatea targetvoice from a second,competing voice. There are at leasttwo hy •H.] ways that exposureto a prior sampleof speechmight aid the perceptual 3aSPS. Formant discrimination in femalellke vowels as a function of segregationof voices.First, peripheral adaptation processes can reduce the Ft--F o !•ark distance. Denni• L. l--lughe•and Randy L. Diehi (Dept.of auditoryresponse to preexistingsounds in order to enhancenewly arriving Psychol.,Univ. of Texas,Austin, TX 78712) energy associatedwith the onset of a secondvoice. Second,perceptual groupingbased on harmonicityor spectrumenvelope cues can reduce the Hughesand Diehl [J. Acoust. Soc. Am. 95, 2978(A)(1994)] reported interferingeffects of preexistingsounds. To separatethe contributionof thatdiscrimination of firstformant frequency for bothsingle and multiple thesefactors, concurrent vowel pairs were preceded by a precursorwhich 3283 J. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128th Meeting:Acoustical Society of America 3283 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp had either the sameF 0 and spectrumenvelope as one of the vowels with significantlygreater accuracy than those with fixedlength. For ap- ("voicedvowel" precursor),the sameF0 but a flat spectrumenvelope propriateduration stimuli, there was no significantdifference for dynamic ("buzz"precursor), or thesame spectrum envelope as one of thevowels, versusstatic tokens. However, for fixed lengthstimuli listeners identified butwith noise excitation ("whispered vowel" precursor). All threetypes of dynamictokens with significantlygreater accuracy than static stimuli. This precursorsresulted in increasedaccuracy when the precursorwas brief suggeststhat intrinsic vowel duration, as expected,is an importantcue to (200ms). When the precursor was 1 s,only the voiced vowel precursor led vowel identityand that dynamicformant information is usedmore by to an increasein identificationaccuracy. These results suggest that both listeners when duration cues are unavailable. adaptationand perceptualgrouping may play a role. 3aSP15.A linear model of boundaryshifts in /u-r]and /•-•/ 3aSP12. Modeling formant frequency discrimination for isolated continua. Anna K. Nabelekand AlexandraOvchinnikov (Dept. of English vowels using excitation patterns. Yijian Zheng and Diane Audiol. and Speech Pathol., The Univ. of Tennessee,Knoxville, TN Kewley-Port (Dept. of Speech and Hear. Sci., Indiana Univ., 3796-0740) Bloomington,IN 47405) Boundary locations were tested for /u-•/ and /3-•/ continua with Thresholds for formant discrimination across three sets of female and steady-stateor linearlychanging formants in whichF2 wasvaried. F1 and male vowelswith differentF0 were significantlydifferent in a recent F2 trajectorieshad upwardand downwarddirections. Boundary shifts report[Kewley-Port et al., J. Acoust.Soc. Am. 95, 2978(A) (1994)].This werecalculated for changingformant stimuli relative to theboundary for analysisexamined whether excitation patterns could model these and other steady-statestimuli. The directions of boundaryshifts indicated perceptual effectsof stimulusparameters on formantthresholds. The goal was to emphasisof thefinal segments of F2 trajectorywhich might be a conse- determineif an "auditory metric" would be constantacross the three quenceof low-frequencyspread of maskingfrom F1 to F2. A linear stimulussets when AF thresholdsvaried by 25 Hz. A separatediscrimi- modelwas developed in whichboundary shifts were related to spectral nationstudy showed that listenersonly attendto harmoniccomponents distancebetween F1 andF2 trajectories.Parameters were initial andfinal withina restrictedregion near the formant[Sommers and Kewley-Port, J. frequenciesof F1 andboundary F2 establishedfor eachcontinuum with Acoust.Soc. Am. 93, 2422(A)(1993)]. Based on thoseresults, four critical steady-statestimuli. When the distancewas constantin time shifts de- bandsaround the alteredformant were selected,and the area betweenthe pendedon directionsof F1 andF2 trajectories,described by two model critical-bandspectra for the standardand just discriminablevowel was termscontaining differences of initial andfinal frequenciesofF1 andF2. calculated.This spectral distance across formant frequency and gender was When the distancewas changingin time additionalshift was towardthe shownto be constant inthree analyses: (li AF thresholddifferences across greaterspectral distance, described by two modelterms containing ratios the three setsof vowelswere no longersignificant; (2) slopesfor AF of initialand final frequencies. [Work supported by NIH.] thresholds(approximately 1.0) were flat for spectraldistance; (3) variabil- ity of spectraldistance across F1 andF2 is significantlysmaller than that 3aSP16.The spectralcenter of gravity effect and auditory filter of AF thresholds.Results suggest that the auditory system has an inherent bandwidth. Marc Fagelson (Dept. of SpeechCommun., Prog. in nonlineartransformation which changes threshold differences to be almost Commun.Sci. and Disord.,Univ. of Texas•Austin, CMA 2.200, Austin, constantin the internalrepresentation. TX 78712)and LindaM. Thibodeau(Univ. of Texas,Austin, TX 78712) 3aSP13. Modeling listeners' categorizationof a large F1-F2-F3 The spectralcenter of gravityrefers to a listener'saveraging of fre- continuum. TerranceM. Neareyand Michael Kiefte (Dept.of Linguist., quencyand intensitycomponents when formant peaks in a speechlike Univ. of Alberta, Edmonton,AB T6G 2E7, Canada) signalare separatedby 3.5 Bark unitsor less.In thispaper a totalof 18 syntheticvowels whose spectra approximated/ae/or/M were generated A numberof alternatespectral representations have been suggested for digitally;each stimulus contained the first40 harmonicsof a 100-Hz fun- vowelspectra [see H. Hermansky,J. Acoust.Soc. Am. 87, 1738-1752 damental.Nine spectracontained three formants, while the balancecon- (1990)].To betterevaluate the perceptual relevance of someof these,972 tainedonly two. Subjects with normal hearing and mild high-frequency vowelswere synthesized. The stimuliwere each 115 msin durationwith a hearingloss above 3000 Hz wereinstructed to identifysynthetic vowels as fallingF0 contour(125-100 Hz). F1 ranged(in 0.5 Barksteps) from 250 either/ae/or/M asF2 frequencywas varied between nine different values to 760, F2 from 750 to 2260, and F3 from 1360 to 3080 Hz. F4 and F5 in 100-Hz stepsfor boththe two-formantand three-formant stimuli. Probit werefixed at 3500and 4500 Hz, respectively.(Constraints were placed on analysisindicated that the normal-hearing subjects identified stimuli more formantseparations to ensurerelatively natural stimuli.) Fifteen speakers consistentlythan the mildly hearing-impaired listeners across F2 frequen- of WesternCanadian English categorized the stimulias thevowels/i, ], e, ciesfor three-formantthan for two-formantspectra. The F2 frequency e, •e, ,x, D, o, U, u, •/. Preliminary results indicate that while nominal correspondingto the perceivedincrease in vowel frontnessoccurred at a synthesisformant frequencies can providea relativelygood fit to the data, lower frequencyfor normal-hearinglisteners. Auditory filter bandwidth alternaterepresentations such as cepstralcoefficients based on Herman- wasnegatively correlated with theF3- F2 Barkdifference. Results sug- sky'sPLP analysismay providemoderate improvements of fit. However, gestthat spectralaveraging may help listeners disambiguate confusing lineartransformations of the PLP cepstrashow strong correlations with speechsignals. formantfrequencies [similar to thosenoted by D. Broadand F. Clermont, J.Acoust. Soc. Am. 86, 2013-2017(1985)]. [Work supported by SSHRC.] 3aSP17.The effectsof pitch changeson the perceptionof vowel sequences. Benira K. Nordenstrom,Magdalene H. Chalikia, and 3aSP14. Formant movement and duration cues in the identification ElizabethM. Ebsen (Dept.of Psychol.,Moorhead State Univ., Moorhead, of vowels. AmyT. Nceland Diane Kewlcy-Port (Dept. of Speechand MN 56563) Hear.Sci., IndianaUniv., Bloomington,IN 47405) Whenlisteners hear a repeatedsequence of steady-statevowels (of the Traditionally,target values of F! andF2 are viewedas primaryde- sameduration and pitch) phonemic transformations occur, and they report terminantsof vowel identity.Several recent studies, however, have dem- hearingwords and phrases absent in theoriginal stimulus. A previous•tudy onstratedthe importanceof dynamicformant information to vowel iden- [M. H. Chalikia,R. Meyer,and R. Lindemann,34th Psychon. Society tification.The presentstudy examines the contribution of bothdynamic Meet.(1993)] investigated the possible effects of variationsin voweldu- anddurational information to vowelidentification using sine-wave vowel ration,pitch, or both.Listeners successfully matched these vowel se- analogs.Sine-wave stimuli consisting of two tonesrepresenting F1 and quencesto theverbal forms heard with vowels of equalduration and pitch F2 wereconstructed using careful LPC measurements of ten vowels pro- (base-linestimuli). Inthis study abroader variation inpitch was employed, ducedin/dVd/context by male and female speakers. Four types of stimuli andthe vowel sounds were computer-generated ratherthan naturally pro- were constructedby varyingtwo factors:(1) appropriateversus fixed duced.Six base-linesequences of six 60-msvowels (at 100 Hz), followed vowelduration and (2) variationin tonesrepresenting formant movement bya 300-mssilent gap, were used. Four variations of thesewere created by throughoutthe tokenversus static target formant values. Listeners identi- randomlychanging the pitch of individualvowels. Most listenerswere fiedthe sine-wave vowel analogs using a key-wordresponse form. Results ableto match the modified vowel sequences to theverbal forms heard with demonstratedthat stimuli with appropriatevowel duration were identified thebase-line stimuli, thus confirming the robust, stable nature of theverbal 3284 d.Acoust. Soc. Am., Vol. 96, No. 5, Pt.2, November1994 128thMeeting: Acoustical Society ofAmerica 3284 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp organizations.It is suggestedthat these organizations are basedupon ob- 3aSP2I. Event-relatedvertex potentialspreceding vowel onset. jectiveacoustic characteristics, and the presentstimulus manipulations NancyHolland and A. Yonovitz(ConIcy Speech and Hear. Ctr., Dept. of wereprobably perceived as prosodicvariations. Commun.Disord., Univ. of Maine, Orono, ME 04469) 3aSPlB.The effectsof duration changeson the perceptionof vowel Neuralevents prior to speechwere determinedby averagingvertex- sequences.Magdalene H. Chalikia and Tammy Dresser (Dept. of recordedpotentials 512 msbefore vocalization. In a manneranalogous to Psychol.,Moorhead State Univ., Moorhead,MN 56563) auditory-evokedpotentials, it wouldseem plausible to identifyspecific sitesalong motor pathways that yield corticallyrecordable electrical po- Previousstudies have shown that listeners exposed to a repeatedse- tentialsthat are precursory to vocalization.In thisstudy, subjects repeat- quenceof steady-statevowels (of sameduration and pitch)experience edlyphonated a schwa500 times.The repetitionrate was approximately phonemictransformations, and report hearing words and phrases absent in 8/mix with the subjectinitiating each trial. The onsetof vocalizationwas theoriginal stimulus. A previousstudy [M. H. Chalikia,R. Meyer,and R. detectedby a throatmicrophone that providedthe trigger.The samplerule Lindemann,34th Psychon. Society Meet. (1993)] investigated the possible (25 000 samples/s)was sufficientto observebrief time periods(10 ms) effectsof variationsin vowelduration. Duration variations ranged from 30 along the averagedprespeech time epoch.The resultsindicated that re- to 120 ms per vowel. Listenerssuccessfully matched these stimuli to Ihe peatable,biphasic potentials were obtained during the time period between verbalforms heard with vowelsof equalduration and pitch, confirming the 45 and 250 ms beforethe onsetof the vowel trigger.Interwave latencies robusl,stable nature of theverbal organizations. It was suggested that these betweenwavelets were highly relatedwithin and betweensubjects. The organizationsare basedupon objective acoustic characteristics, and the techniqueof event-relatedpotentials may be a usefulprocedure for study- stimulusmanipulations were probably perceived as prosodic variations. In ing the electrophysiologyof speech production in normaland disordered thisstudy a broadervariation in duration was employed (10-300 ms),in an speakers. attemptto examinelisteners' limitations in performingthe matching task. Six base-linesequences of six 80-msvowels (at 100Hz), followedby a 3aSP22. Development of a microcomputer based system for 300-mssilent gap, were used.Four variations of thesewere createdby evaluating hypernasalityin vowels of cleft palate patients. Ryuta randomlychanging the durationof individualvowels within a sequence. Kataoka (UNC CraniofacialCtr., Univ. of NorthCarolina, Chapel Hill, Most listenerswere not ableto performthe task.Implications concerning NC 27514), Ken-ichiMichi (ShowaUniv., Tokyo, Japan), and Kaoru the perceptualorganization of speechwill be discussed. Okabe (CorctexCorp., Tokyo, Japan) 3aSPI9. Perceptual implications of selected aspects of vocal To evaluatehypemasality quantitatively, frequency analyses were per- behavior. Shaft L. Campbell (Dept. of Commun.Sci. and Disord.,576 formedon the Japaneseisolated vowel/i/produced by sixteencleft palate AderholdHall, Univ. of Georgia,Athens, GA 30602) patientswith or withoutspeech appliances and four normalsubjects. These 26 speechsamples were rated by 20 listeners.Analysis of the one-third- The perceptualdimensions derived from acoustical changes associated octavepower spectra revealed an increasein powerlevel between the first with vowelquality, voice quality, voice classification, and genderare not and secondformant and a reductionin secondand third formantregions clearlydefined. This projectuses the trainedsinging voice as a sourceof amonghypernasal speech samples. Factor analysis of the five-pointlisten- controlledvariation in parametersimportant to the timbreof bothspeech er's ratingsrevealed that the consensusperception of hypemasalityac- andvoice. A databaseof vowelswas collected from 18 singersrepresent- countedfor 75% of the total variance.Multiple regressionanalysis re- ing six majorvoice classifications. Repetitions were made of threevowels vealeda high correlation(0.82) betweenthe perceptionof hypernasality at threeor four fundamentalfrequencies and at threedynamic levels in and the peaklevels of two clustersof l/3-octavebands: the sixth,seventh, normalregister. Six subjectsalso atlempted to matchloudness (as indi- and eighlh l/3-oclave multiples,and the tenth,eleventh, and twelfth mul- catedby a targetof equalphons) for thisisoparametric condition. Spectral tiplesfrom the bandcontaining the fundamentalfrequency. Based on these measures(e.g., FFTs, STFTs, 1/3-octave band levels) were transformed in findings,a systemfor evaluatinghypernasality was developedusing a a mannerintended to approximatepereeptually relevant aspects of auditory computerand 1/3-octavebandpass filter. This approachis presentlybeing processing(e.g., loudness and sharpness densities and loudness and sharp- usedto assessthe relationshipbetween velopharyngeal port area obtained nessover time). By comparingthe spectralmeasures with their transfor- from pressure-flowstudy and hypernasalityevaluated by this system. mations,it may be possibleto make inferencesconcerning which acous- tical changesare perceptuallyrelevant, and aboutthe natureof their 3aSP23. A noninvasiveEM based speechfeature estimation method perceptualrepresentation. [Work supported by the[nstitute for Perception for analysis and recognition of vocal fold cancer. Liliana Research,Eindhoven, The Netherlands.] Gavidia-Ceballos(Robust Speech Processing Lab., Dept. of Biomedical Engineering,Duke Univ., Box 90291, Durham, NC 27708-0291) and 3aSP20. Evaluating speech quality with adaptive psyehophysical John H. L Hansen (Duke Univ., Durham, NC 27708-0291} methods. Muralidhar Kuduma[a (Elec. Eng., Univ. of Oklahoma, The focusof this study is to formulatea speechparameter eslimation Norman, OK) and Bias Espinoza-Varas (Univ. Oklahoma Heallh SciencesCtr., OklahomaCity, OK 73190) algorithmfor analysis/detectionof vocal fold cancer,which does not re- quiredirect estimation of the glottalflow waveform.The proposedmethod Thisstudy examines some advantages of adaptivepsychophysical tests separatesspeech components under healthy and assumedpathology con- for obtainingreliable and efficient estimates of speechquality. Specifically, ditionsusing a mixedexcitation speech model. This problemis addressed in vowelscorrupted by additivenoise, noise-detection thresholds were usingan iterativemaximum-likelihood (ML) eslimationprocedure, based measuredadaptively. The 350-msvowels were obtained by additionof the onthe estimation-maximization (EM} algorithm.Two new features, termed first32-35 harmonicsof 100-200 fundamentalfrequencies, with spectral enhancedspectralpathology component (ESPC) and mean area peak value envelopesappropriate for lil and lag.Noise was synthesizedby random- (MAPV) index are estimatedand shownto vary consistentlybetween phaseaddition of harmonicsof a 10-Hz fundamental;the noisebandwidth healthyand pathologyconditions. For classification,a hiddenMarkov andIhe spectralenvelope were equal to thoseof thevowels. In a 2IFC task, model recognizeris formulatedusing MAPV and/or ESPC spectralfea- subjectshad to determinethe observationinterval that contained a "noisy tures.Classifier evaluations using speech recordings from healthyand vo- vowel." Duringa blockof trials,the noiselevel was variedusing a "two- cal fold cancerpatients for sustainedvowels, showed that while MAPV is down,one-up" rule (Levitt, 1971};the test terminatedwhen the subject a usefulfeature for vocalfold cancerdetection (88.7%), superiorperfor- completed6-8 reversals,and thresholds were defined as the average noise mancewas achieved using a finerspectral representation of ESPC (92.8%). level obtainedin the last three reversals.The adaptive method yielded Sincedirect glottal flow estimationis not necessary,the inabilityto accu- thresholdestimates in muchfewer trialsthan a constantstimuli procedure ratelycharacterize vocal fold pathology due to incompleteglottal closure is usedin previousstudies. The adaptivemethod was implemented in LAB- no longeran issue.The resultssuggest that the ESPC featurecan provide VIEWsoftware, National InstrumentsDSP boards,and a Macinlosh com- a noninvasiveapproach for analysis,detection, and characterizationof puter.[Work supported by OCAST.] speechproduction under vocal fold pathology. 3285 J. Acoust. Soc. Am., VoL 96, No. 5, Pt. 2, November 1994 128th Meeting: Acoustical Society of America 3285 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp WEDNESDAY MORNING, 30 NOVEMBER 1994 BALLROOM B, 8:00 A.M. TO 12:00 NOON Session 3aUW UnderwaterAcoustics: Moderate-to-High Frequency Bottom Interacting Acoustics III Nicholas P. Chotiros, Chair AppliedResearch Laboratories, University of Texasat Austin,P.O. Box 8029,Austin, Texas 78713-8029 ContributedPapers 8:00 nuisanceto be gottenrid of if possible.Here the possibility that the fluc- tuationsmay actually provide a meansto learnmore about the scattering 3aUWl. Acoustic phase stability in a shallow-water environment. processthan would be possiblewith an unchangingsignal is considered. ChristineT. Mire and StephenStanic (Naval Res. Lab., Code 7174, Laboratoryexperiments are describedin whichknown targets are insoni- StennisSpace Center, MS 39529) fled in thepresence of artificiallyinduced thermal fluctuations. The result- The formationof a syntheticaperture is dependenton the phasesta- ingbackscattered signals are discussed and analyzed within the framework bility of the medium.Temporal and spatialphase stability of the medium of a weakscatter theory. Possible applications to oceandata are pointed wereestimated from measurements taken during a high-frequencyexperi- out.[Work supported by ONR andNRL.] mentconducted inAugust 1993 in theshallow-water coastal environment off PanamaCity, Florida. Phase stability was estimated from sequences of 8:45 150 0.5-msand 1.0-ms pulses separated by 1-s intervalsat experimental frequenciesof 20, 40, 60, and 90 kHz. Phasefluctuations were found to 3aUW4. Bistaticbottom scattering at high frequencies:Experiment containboth deterministic and random components which changed with and modelcomparison. Kevin Williams and Darrell Jackson (Appl. time,indicating a changingpropagation environment. Phase fluctuations Phys.Lab., Univ. of Washington,1013 NE 40th St., Seattle,WA 98105) werespatially correlated between both vertical and horizontal components of the receivingarray. The relationshipbetween acoustic phase stability In 1993a specialresearch program on Coastal Benthi c Boundary Lay- andenvironmental factors is examined.Results of thisanalysis are com- ers(CBBL) was begun. As part of thatprogram an autonomous, spatially paredwith previousphase stability measurements [J. T. Christoff,C. D. scanning,sonar system was deployed ina well characterized regions inthe Loggins,and E. L. Pipkin,J. Acoust.Soc. Am. 71, 1606-1607 (1982);P. BalticSea andoff the coastFlorida. The goalwas to examinehigh- T. Goughand M.P. Hayes,ibid. 86, 837-839 (1989)]. [Work sponsored by frequencyacoustic scattering from the sediment. This sonar operated at 40 ONR.] kH7,had a 5ø horizontalbeamwidth, and acquir6d backscattering data within a 50-m radius area at least once an hour for several weeks at each site.During part of eachdeployment it operatedin conjunctionwith a 8:15 mobilereceiving array so as to acquirebistatic data. The bistatic experi- mentalapparatus, procedures, and results are presented. Finally, a recently 3aUW2.Acoustic pulse to pulsevariability due to seawatertemporal developedbistatic model (driven, in part,by the environmental parameters temperature fluctuations. Li Zhang (Ctr. for Marine Sci., Univ. of measuredat the experimentalsite) is testedagainst the experimentalre- SouthernMississippi, Stennis Space Center, MS 39529), Ralph sults.[Work supported by NRLCBBLSRP program.] Goodman (PennState Univ., StateCollege, PA 16804), and Steve Stanic (NavalRes. Lab., Stennis Space Center, MS 39529) 9:00 Mireand Stanic (preceding abstract) have observed significant pulse to pulsefluctuations in high-frequencyseafloor backscattering measurements 3aUW5. Acousticbackscatter analysis from a smoothsand surface. in which the sound sources and receivers were mounted on a tower that JuliaLaughlin and Nicholas P. Chotiros (Appl. Res.Labs., P.O. Box stoodon the seafloorin a shallow-waterenvironment (about 30 m). This 8029, Austin,TX 78713-8029) paperpresents the hypothesisthat temperature fluctuations that are asso- A multlscatteringtheory to describebackscatter behavior in water- ciatedwith turbulence can account for theacoustic variability. The model filledsands has been developed for smoothsand surfaces. The theory is is basedon a randomdistribution of fixeddiscrete scatters on thesurface basedon a two-dimensionalsolution of thediffusion equation and a Biot of theseafloor. Computations that sum the arrivals of scatteredCW pulses propagationtheory for porousmaterials. Experiments were conducted at for a range of changesin travel times that are due to varietiesin the highfrequencies (80-120 kHz) to measurebackscatter atshallow grazing averagetemperature along the pathsreveal fluctuations similar to Mire and anglesfrom smooth sand surfaces at variedsand depths. In addition,re- Stanic'sobservations for a rangeof tensof meters,temperatures 'changes flectionmeasurements were made at normalincidence to verifythe as smallas a tenthof a degreeCelsius, and frequencies of about40 kHz smoothnessof the sandsurface. Comparisons of theoreticalmodel back- andhigher. Comparisons between computations and measurement are pre- scatterresults to experimentalmeasurements were then made. [Work sup- sentedin thispaper. [Work supported by NRL/Stennis.] portedby ONR, OceanAcoustics Program, Code 11250A.] 8:30 9:15 3aUW3. Laboratorymeasurements of variabilityin high-frequency 3aUW6. The effect of gradients on high-frequencybottom bottom backscatterdue to thermal fluctuations. P. JasonWhite, scattering.John E. Moeand Darrell R. Jackson(Appl. Phys. Lab., Univ. KennethE. Gilbert,and RalphR. Goodman (Appl. Res.Lab. and the of Washington,1013 NE 40th St., Seattle,WA 98195) GraduateProg. in Acoust.,Penn State Univ., P.O. Box 30, StateCollege, PA 16804) Thefirst-order perturbation expression for thebistatic scattering cross sectionof a roughsurface [Moe and Jackson, J. Acoust.Soc. Am. (to be From the WorldWar 11era to the present,researchers in oceanacous- published)]is used to studythe effect of gradientson high-frequency ticshave observed fluctuations (scintillation) in high-frequency backscatter bistaticbottom scattering. Strong gradients on scales of severalcentimeters fromthe seafloor.In general,the fluctuationshave been regarded as a areoften observed in shallow-water environments. It isshown that upward 3286 J.Acoust. Soc. Am., Vol. 96, No. 5, Pt.2, November1994 128thMeeting: Acoustical Society of America 3286 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp refractionorreflection by strong gradients can lead to significantenhance- andstrong mixing prevents stratification (bulk Richardson number •0.02). mentof high-frequencyscattering. This enhancementoccurs over a wide Prior experimentshave establishedthe turbulentnature of the flow and rangeof bistaticangles, but is strongestwhen the incidentand scattered examinedthe horizontal arrival angle and intensity fluctuations with time. grazingangles are equal. These effects can be explainedin termsof the In thepresent experiment, a new compact acoustic array, consisting of 128 reflectioncoefficient of the corresponding mean (flat) surface. [Work sup- hydrophonesin an elliptical configuration, is being adapted to monitorthe portedby ONR.] acousticarrivals in thevertical and horizontal, with finer spatial resolution thanhas previously been obtained. Amplitude and phase data will be re- 9:30 cordedfrom 15 channels.Environmental data from ADCPs,turbulence meters,side-scan sonars, microstructure instruments, CTDs, etc., will be 3aUW7. Temporalcoherence and stabilityof bottominteracting availableto help interpretthe acousticresults. Preliminary results of the soundpulses. Xin Tangand Fred D. Tappert(Appl. Marine Phys., acousticfluctuation experiment will be presented,with an analysis of the RSMAS,Univ. of Miami,4600 RickenbackerCswy., Miami, FL 33149) fine-scalephase and intensity coherences, which are intimately related to the microstructureof the transmittingmedium. Soundpropagation at moderate frequencies (depth to wavelengthratio between20 and100) in shallow-waterenvironments is extremely compli- cated,variable, and poorly understood due to muMpieprocesses that cover 10:30 a widerange of temporaland spatial scales. Broadband full-wave numeri- calsimulations are performed with the UMPE model at a largenumber of 3aUW10. High-frequencysound variation in a coastalenvironment. geophysicaltimes to displaythe temporal variability, stability, and coher- JulesS. Jaffe (MarinePhys. Lab., Scripps Inst. of Oceanogr.,La Jolla, CA 92093-0238) enceof acousticpulse arrivals in a multipathenvironment that includes multiplerough bottom forward scattering and multipleforward volume Despitethe proliferation of high-frequencysonar imaging systems, the scatteringby internalwaves that are described by eithera Garrett-Munk variabilityof high-frequencysound propagation in shallowwater has only typeof spectralmodel or a solitontype of model.It is foundthat the effects recentlybeen measured. In a seriesof experimentsadjacent to theScripps of roughbottom scattering change the phasestructure while the effectsof Institutionof Oceanographypier, the variability of soundat a frequencyof internalwaves account for theobserved temporal fluctuations, leading to 450 kHz hasbeen measured. The experimentalmeasurement consisted of coherencetimes of minutesfor individualmultipaths at 20-kmranges, and deployinga multibeam imaging system on a tripodin approximately20 ft a stableenvelope having a coherencetime of hours.[Work supported by of water.Repeated insonification and subsequentmeasurement of the ONR.] backscatteredwaveforms indicate that a largedegree of variabilitycan exist in the backscattereddata. In order to define whether the sourceof the 9:45-10:00 Break variabilityin thebackscattered data was originating from the bottom or the volume,a cornerreflector was deployed. Assuming that the variability in thesound reflected from the bottom consists of thesuperposition of both 10:00 volumeand the bottomvariability, and that the soundfrom the comer 3aUW8. Temporal model of high-frequencyseafloor acoustic reflectorconsists of variabilityonly from the volume,assignment of the backscatter.Christian de Moustierand Daniel Sternlicht (Marine Phys. relativeimportance between the two forms of variabilitycan be made. The Lab., Scripps Inst. of Oceanogr.,9500 Gilman Dr., La Jolla, CA importanceof thesetwo sourcesof variabilityas a functionof environ- 92093-0205) mentalconditions such as tide and surfaceconditions will be presented. [Worksupported by ONR.] A monostatictemporal model of seaflooracoustic backscatter has been developedto investigatethe relativecontributions of interfaceroughness and inhomogeneitiesin the sedimentvolume for measurementsmade at 10:45 variousangles of incidence.The modeltakes into accountsonar param- 3aUWll. Dereverberationof shallow-water, high-frequency signals. eterssuch as acoustic wavelength, beam pattern, pulse length, and angle of JeanO. Nam andJ. RobertFricke (Dept.Ocean Eng., Cambridge, MA incidence,and it includesa theoreticalangular dependence of seafloor 02139) scatteringstrength that is controlledby the roughnessstatistics of the surfaceinsonified, by its refractionindex, and by a volumereverberation Propagationof high-frequencysignals, O(10 kHz), in a shallow-water term. Simulationshave been carried over anglesof incidencefrom 0ø to channel,O(10 m), is complicatedby multipatheffects associated with the 60ø, andat acousticfrequencies ranging from 10 to 100 kHz for various surfaceand bottom. The goalof this researchis to alereverberatethe time typesof substrates.The theoreticalangular dependence predicts that the spreadand dispersedreceived signal into a processedsignal with a tem- contributionfrom the sedimentvolume becomes noticeable for anglesof poralduration comparable to thatof theoutgoing pulse. Given the impulse incidencegreater than about6ø; however,in the temporalmodel it is responseof thechannel and the received signal, an inverse filtering method shown that this contribution can be detected closer to normal incidence for utilizingminimum-phase components can be effective.However, because smallbeamwidths (e.g., 2ø). When applied to a multi-narrow-beamsonar of channeldynamics caused by turbulence,internal waves, and thermal geometrythis temporal model shows greater potential for bottomclassifi- stratification,calculation of the exactimpulse response is impossible.A cationthan the angulardependence function of acousticbackscatter ob- morerobust signal recovery method, known as cepstralsmoothing, has tainedby integratingthe returns received in eachbeam. [Work supported beendeveloped to separatethe signal from the channel impulse response in by ONR.] the cepstraldomain. Using this method, the recovery is independentof the channelimpulse response and is robustin the presenceof additivenoise. 10:15 Thecepstral smoothing method dereverberates the original signal, but ab- solutetime delay informationis lost.A movingrms window applied to the 3aUW9. Spatial coherence of high-frequency (67-kHz) acoustic originalreceived signal recovers the losttime delay. fluctuationsin fully developedturbulence. MichaelJ. Buckingham, JohnR. Potter,and Grant B. Deane (MarinePhys. Lab., Scripps Inst. of 11:00 Oceanogr.,La Jolla,CA 92093-0213) 3aUW12. Shallow-waterreverberation measurement and prediction. As partof ONR's high-frequencyinitiative, a fieldexperiment to de- JamesH. Miller,Charles E. Muggleworth,Ching-Sang Chiu (CodeEC/ terminethe temporal and spatial coherence of acousticfluctuations induced Mr, Naval PostgraduateSchool, Monterey,CA 93943), and JamesE by propagationthrough a fully developedturbulent flow has been planned Lynch (WoodsHole Oceanogr.Inst., Woods Hole, MA 02543) in collaborationwith severalother researchgroups for late September 1994.Narrow-band measurements (67-kHz coded signals) will he takenin In August 1992, a shallow-water,low-frequency reverberation mea- CordovaChannel, British Columbia,where strong, semidiurnal tidal flows surementwas madein the BarentsSea utilizingexplosive SUS chargesas (upto 1.0 m/s) create fully developed turbulence (Reynolds number • 107), soundsources and a middepthhydrophone as the receiver.The objectives 3287 J. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128th Meeting:Acoustical Society of America 3287 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp of thiswork were to analyzethe reverberationdata from this experiment, sourcesin an oceanenvironment. A sonobuoyfield wasfirst deployed in a compareseveral theories which have been proposed to modelreverbera- ring-typepattern. GPS receivers were installed on the buoys to obtaintheir tion,develop a techniquefor estimatingthe bottom backscattering coeffi- locationswithin a few metersof accuracy.Charges were then set off at cient in shallowwater from singlehydrophone acoustic data, and deter- arbitrarylocations within the ring. High-resolutionplots were used to minethe reverberentcharacteristics of the experimentalregion. The three- obtaindirect path and first bottombounce arrivals on eachbuoy. A model dimensionalHamiltonian Acoustic Ray-tracing Program for the Ocean gridof arrivaltimes was constructed, corresponding to the dimensionsof (•a•,o) was usedas the primarypropagation modeling tool. The temporal thebuoy field. A raymodel previously developed here at ARL:UT [E. K. signalprocessing consisted of a short-timeFourier-transform spectral es- Westwoodand P.J. Vidmar,J. Acoust.Soc. Am. 81,912-924 (1987)] was timationmethod applied to datafrom the singlehydrophone. Chapman's usedto obtainmodel travel times.The minimumvalue of the least-square sourcespectrum model was used. A bistatic Lambert'sLaw with a error between the real arrival times and the modeled travel times resulted frequency-dependentconstant was foundto fit the data from the experi- in an unambiguouslocation of the source,within the limits of the grid ment.A statisticalanalysis showed that the reverberationfrom the Barents spacingchosen. This value was calculatedby picking one phoneas the Sea experimentwas Gaussianto a high degreeof confidence. referenceand then summingthe errorsof each phonerelative to the ref- erence.Successive iterations with finer grid spacingsresults in source 11:15 locationwithin the accuracyof the buoy locations.Results obtained at Lake Travis and the Gulf of Mexico will be presented.[This work is 3aUW13. Shallow-water backscatter reduction through selective supportedby Navy StrategicSystems Programs.] modeexcitation. D.F. Gingras (SACLANT UnderseaRes. Ctr., Viale San Bartolomeo,400, 19038 La Spezia,Italy) 11:45 In shallow-waterareas the utilizationof activesonar is complicatedby thefact that in theseenvironments the performance of activesonar systems 3aUW15. Broadband source localization in a shallow-water is degradedby backscattergenerated by sourcesignal interaction with environment with a small bottom slope. David P. Knobles and channelboundaries. In this paper knowledgeabout the shallow-water RobertA. Koch (Appl.Res. Labs., The Univ.of Texasat Austin,Austin, acousticchannel, namely the normal-modestructure, is usedto design TX 78712) verticalsource arrays which minimizesource signal boundary interaction. Resultsfrom an analysisof matched-fieldsource localization in range The boundarysignal interaction is minimizedfor manyenvironments by and depth for a range-dependentshallow-water ocean environmentare exciting only the first mode. Mode one excitationis accomplishedby presented.The matched-fieldlocalization is basedon a broadbandcross- weightingthe arraysources by the amplitudeand polarity of the modeone correlationtechnique. The measureddata are the time seriesof acoustic eigenfunction.Simulations across the frequencyrange from 200 to 700 Hz arrivals that propagatedto a bottom mounted array from small omni- usinga two-wayPE backscattermodel were conducted.It was shownthat a verticalarray of sources,containing only 15 elements,can reduce bottom sourcesat a location0.5-30 km downslope.Over theseranges the water depthwas 125-180 m. The measureddata contain many strong multipaths generatedbackscatter by as much as 15-20 riB. becausethe acousticenvironment was a downwardrefracting water col- umn and a seafloor with a thin sand-silt sediment over a thick limestone 11:30 layer. Matchingfields for the localizationof the sourcesin the measured 3aUW14. Source localization via received arrival time structure datawere computedwith a broadbandadiabatic normal-mode model in the analysis. S.A. Stottsand N. R. Bedford (Appl.Res. Labs., The Univ.of 100-500-Hz band.The presentationalso includesa comparisonof the measured and modeled time series as a validation of the environmental and Texas at Austin, P.O. Box 8029, Austin, TX 787123) propagationdescriptions. [Work supportedby the Office of Naval Re- An efficientand robust method has been developed to locateimpulsive search(Code 322). The datameasurements were sponsored by ARPA.] WEDNESDAY MORNING, 30 NOVEMBER 1994 NUECES ROOM, 9:00 A.M. Meeting of AccreditedStandards Committee S2 on MechanicalVibration and Shock to be heldjointly with the U.S. TechnicalAdvisory Group (TAG) Meeting for ISO/TC 108 Mechanical Vibration and Shock D. J. Evans, Chair S2 National Instituteof Standardsand Technology(NIST), Building233, RoomA 147, Gaithersburg,Maryland 20899 D. F. Muster,Chair, U.S. TechnicalAdvisory Group (TAG) for ISO/TC 108, MechanicalVibration and Shock 4615 O'Meara Drive, Houston, Texas 77035 StandardsCommittee S2 on MechanicalVibration and Shock. Working group chairs will presentreports of theirrecent progress on writing and proceaaingvariou• •hock and vibration •tandard•.There will be a reporton the interfaceof S2 activitieawith thoaeof ISO/TC108 (the Technical Advisory Group for ISO/TC108 consists of membersof S2,S3, and other persons not necessarily members of thosecommittees) including a reporton theactivities of [SO/TC108, including its September1994 meeting in Berlin,Germany. Scopeof S2: Standards,specifications, methods of measurementand test, and terminology in the fieldsof mechanicalvibration and shock,and condition monitoring and diagnostics of machines,but excluding those aspects which pertain to biologicalsafety, tolerance and comfort. 3288 J. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3288 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp WEDNESDAY AFTERNOON, 30 NOVEMBER 1994 SAN ANTONIO ROOM, 1:00 TO 3:00 P.M. Session3pEA EngineeringAcoustics: Acoustical Measurement and InstrumentationII Elmer Hixson, Cochair Departmentof Electricaland ComputerEngineering, University of Texas,Austin, Texas 78712 Kevin Baugh,Cochair AppliedResearch Laboratories, University of Texas,P.O. Box8029, Austin, Texas 78713-8029 ContributedPapers 1:00 3701 Hawkins St. NE, Albuquerque,NM 87109-4512), and Russ Roberts(Enigmatics, Inc., New Harmony,UT 84757-0537) 3pEAl. Target responsemeasurement system for the NUWC Lake SenecaTest Facility. David M. Deveau,Lynn F. Carlton (Naval For timeslong comparedto the acousticwave transittime in a test UnderseaWarfare Ctr. Range DevelopmentDiv., B104/Code3822, tank,the signal from point acoustic sources may be dominated by internal Newport,RI 02841), and Peter J. Stein (ScientificSolutions, Inc., reflectionsand the modalresponse of the experimentaltank in which Nashua,NH 03062) experimentsare performed. If the free-fieldsource behavior of the acoustic sourceis desired,it canbe extracted by takingadvantage of specialprop- Here is presentedan overviewof the targetresponse measurement ertiesof the source/tanksystem. The transducercan be operatedin a system(TRMS) deployed at theNUWC Seneca Lake test facility. This mannerwhich permits characterization of the tankresponse; then the pro- systemis capableof measuringthe target strength of objectsat rangesfrom cessedresults can be usedto reducethe effects of thetank response in the 10 to 300 m. The frequencyrange for monostaticmeasurements is from signalsof interest.Spectral methods for this signalprocessing will be 300 Hz to 400 kHz.The current bistatic capability is measurementsevery describedand illustrated. The result is thatsignal characteristics in spectral 5ø overa 90ø windowfrom 2 to 15 kH2.A multichannelPC-based digital regionsof interestcan be more clearly resolvedand enhanced.[Work data-acquisitionsystem has been developed which includes high-speed sponsoredby U.S. Navy.] A/D boards,baseband translation, and real-timemonitoring of TS as a functionof targetaspect angie. Target aspect angie and acousticsource signaturesare measured at thetarget and telemetered to theacquisition for 1:45 digitalstorage along with the acousticdata. Accuracies of 1 dB in TS and 1ø resolutionin targetaspect angle are possible. Measurements aregener- 3pEA4. The design,construction, and performancetesting of an ally clutterlimited to a targetstrength less than -30 dB re: 1 m. Clutterof acousticalagglomeration chamber. Laura A. Dudes,M. G. Prasad, thetarget harness is usuallya majorissue and is discussed.The target andR. F. McAlevy,III (Dept.of Mech.Eng., Stevens Inst. of Technol., strengthof varioustargets and support structures is presented. CastlePoint on the Hudson,Hoboken, NJ 07030) An acousticalaggiomeration system is an apparatuswhich can be used to enhancethe efficiency of currentparticulate removal devices. This study 1:15 presentsthe designand construction of an acousticalagglomeration cham- ber andassociated measurement instrumentation. The systemconsists of a 3pEA2. Five axis programmablepositioning system for underwater main chamber3.05 m longwith an innerdiameter of 0.075 m. The dimen- acousticmeasurements at Penn State. Kyle M. Becker (Graduate sionsare sufficient to developthe particulate gas stream as well asacous- Prog in Acoust.,Penn State Univ., Appl. Res. Lab., StudentArea, P.O. ticalplane-wave fields up to 2500 Hz. The inletflow velocitiesof thegas Box 30, StateCollege, PA 16804) streamrange from 0.5 to 5 m/swith operatingpressures ranging from 101 To facilitateunderwater acoustic measurements at Penn State,a five to 1010KPa. A midrange(e.g., 200-4000 Hz) heavyduty electroacoustic axis computercontrolled positioning system has beendeveloped by the driver is usedas the soundsource. The particulatesize distributionis authorand installedin the new watertank facilitiesat the AppliedRe- opticallymeasured with a Malvern2600 laserparticle sizer. A silencerwas searchLaboratory. Providing linear motion in threedirections and rotations usedto reducethe noiselevel coming out of the agglomerationchamber. abouttwo axes,the systemallows an acoustictransducer to be positioned The performancetesting of the aggiomerationapparatus was carriedout andoriented at virtuallyany positionand direction within the watertank. usingaluminum oxide particulate with frequenciesof 1 and2 kHz in the Motionis controlledalong each axis via programmablecontrollers (index- rangeof sound-pressurelevels between 140 and 160 dB. An increasein ers)which are in turnedaccessed by a computervia RS 232. Resolutionin particulatesize from 16 to 26/.•m was achievedin the preliminarymea- the lineardirections is 0.005 in. Angularresolution is 0.18ø . Workingin surements.This studywill haveapplications in reducingemission of haz- conjunctionwith the appropriatedata-acquisition hardware and software, ardous,fine particulateinto the atmosphere.[Work supportedby New the positioningsystem allows the entiremeasurement procedure to be JerseyHazardous Substance Management Research Center.] automated.Although designed initially for usein monostaticand bistatic surfacescattering experiments, the systemis alsobeing used for other interestingunderwater experiments, including bottom sediment studies, 2:00 andthe effectsof thermalgradients on acousticsignals. 3pEAS. Characterizingthe performanceof piezoelectricceramic as a function of stress,electric field, and thermal history. R. Lowell Smithand Alan V. Bray (TexasRes. Inst., 9063 Bee CavesRd., Austin, 1:30 TX 78733) 3pEA3. Wideband reverberation reduction in long-time acoustic The relativelyrecent development of largeflextensional and other low- signals produced by transducersin small test chambers. Niels K. frequency,high-power transducers has stimulatedrenewed interest in the Winsor,Gary R. Hess,Forest E. White, Chris M. Young (TetraCorp., performanceof piezoelectricceramic under conditions of high stressand 3289 J. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128th Meeting:Acoustical Society of America 3289 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp electricfield. This paperaddresses the developmentof specialfixturing for 2:30 the assemblyand testing of structuresemulating the useof PZT-8 material in high-powerprojectors. The testfixtures themselves are Tonpilz oscilla- 3pEA7. Measurementof throat impedanceand far-field directivity tors.Using a systemof fourtie rods,axial loads as high as 2.2x10 • N for acoustichorns. JohnT. Post (KlipschProfessional, P.O. Box 1320, (50 000 lbf) canbe applied.The tie rodsare fired with straingauges so Hope,AR 71801) and Elmer L. Hixson (Univ. of Texas,Austin, TX 78712) that load can be monitoredas oftenas desiredduring the courseof aging and stressand electricaldrive sensitivitystudies. Initially data were ac- Experimentssuitable for the measurementof throatimpedance and quiredfor combinedstatic and dynamicstress in a controlledthermal directivityof acoustichorns were designedand implementedusing an environment.The performancecharacteristics of the piezoelectricceramic axisymmetricexponential and tractfix horn. The hornshave equal length are inferredfrom electricaladmittance measurements. Providing for the (55.9 cm), throatradius (2.54 cm), andmouth radius (27.1 cm).A modem incorporationof extensometersand closed-loop control of axial stressal- implementationof the "reactionon the source"method was compared lows the fixturesto be usedfor a numberof broaderapplications such as with a two-microphonemethod for the measurementof acousticimped- measurementof theviscoelastic properties of ceramic.[Work supported by ance. The indirect reaction on the source method was found to be less SPAWAR.] accuratebut hasthe capabilityof in s/m-typeimpedance measurements. Thefar-field pressure was derived by measuringthe near-field pressure and 2:15 mathematicallyextrapolating to the far field, a techniquewhich has been usedin the areaof antennassince the early 1970s. 3pEA6. Determinationof effectivepiston area by three methods. S. L. Garrettand D. F. Gaitan (Phys.Dept. Code PH/Gx, Naval Postgraduate 2:45 School,Monterey, CA 93943) 3pEA8. Measurement of three.dimensional transient motion of The volumetricvelocity of an acousticsource is sufficientto charac- surfacesby opticalvibrometry. JosephVignola, Harry Simpson (SFA, terizeits sourcestrength if theacoustic impedance of theload presented to Landover,MD 20785), and Brian H. Houston (Naval Res. Lab., the sourceis known.Although a calibratedaccelerometer can accurately WashingtonDC 20375-5000) determinethe velocityof a piston,the volumetricvelocity requires a de- A three-dimensionallaser vibrometer for measuringsimultaneously the terminationof the effective area of the "piston." For a thermoacoustic threecomponents of vibrationinduced displacement on a surfacehas been refrigeratoroperating at resonance,this load is purely resistive.Three constructedand tested[Vignola and Houston,J. Acoust.Soc. Am. 94, methodsfor determiningthe effectivearea of an electrodynamicthermoa- 1853(A) (1993) andASME WinterMeeting, 93-WA/NCA-10 (11/93)]. cousticdriver will be presented.For in situmeasurements, good agreement The device,which is fully submersible,was developedfor structural (---2%-4%)was obtained between direct measurement of the force, using acoustic studieswhere measurementsof full three-dimensionalmotion can theknown Bl productand the resonant reciprocity method using the trans- provideinsight into the analysis of thesound radiated by a structure.This fer impedancecalculated by Rudnick[G. W. Swift,A. Migliori,S. L. presentationis principally concerned with the methodology and design of Garrett,and J. C. WheatIcy,Rev. Sci. Instrum.53, 1906-1910 (1982)]. the signalprocessing schemes for the detectionof transientevents. Some The resultfor effectivearea obtained by measurementof pressureunder preliminarydata are showntogether with an analysisof thesensitivity, thereactive load presented by a smallcoupler [T. Hofier,J. Acoust.Soo. noisesources, and other performance characteristics of the system. The Am. 83, 777-786 (1988)]was smaller and more pressure dependent. A datapresented has been collected from both a teststructure (a piezoelectric possibleexplanation for this discrepancy,based on bellowsdeformation cylinderwith threeaccelerometers for comparison)and in a water tank underdifferent loading, will be presented.[Work supported by ONR, the half-filledwith filteredsand (mean diameter of 140 /am). In the sand Naval PostgraduateSchool Direct FundedResearch Program, and the experimentthe motion of the water-saturatedsand interfacewas moni- Navy ScienceAssistance Program.] tored. WEDNESDAY AFTERNOON, 30 NOVEMBER 1994 WEDGWOOD ROOM, 1:30 TO 2:35 P.M. Session3plD Interdisciplinary:Hot Topicsin Acoustics Uwe J. Hansen, Chair PhysicsDepartment, Indiana State University,Terre Haute, Indiana 47809 A specialsession on "HotTopics on Acoustics" is presentedat eachmeeting of theSociety. A memberis chosenfrom each of three orfour of theSociety's technical committees orspecialty groups to present a tutorial talk on topics of currentspecial interest. The talks areintended tohelp acousticians become familiar with issues and achievements thatare not within their own primary fields of interest. Chair's Introduction--l:30 Invited Papers 1:35 3plD1.Hot topicsin architecturalacoustics. Gary W. $•ebein(Architecture Technol. Res. Ctr., Univ. of Florida,231 ARCH, Gainesville,FL 32611-2004) Thislecture will review some of thecurrent topics of interestin thearchitectural acoustics community. There has been much recent workin tryingto determinewhat physical factors contribute to subtleperceptions of spaciousness and source width in rooms.Efforts 32g0 J.Acoust. Soc. Am., Vol. 96, No.5, Pt.2, November1994 128thMeeting: Acoustical Society of America 32cj0 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp tostandardize measurement techniques forrecently proposed acoustical measures derived from the impulse response of rooms is underwayaswell as experiments todetermine theutility of these measures inapplied situations. These measures arealso predicted in roomsby testsin physicalscale models and computer models. Aural simulation of theeffects of theamhitectural features of roomson thequalities of music and speech isalso being pursued. Measurements of the effects of flankingtransmission, plumbing noise, and impactnoise are also being refined as are recommended methods for assessing background noise levels in rooms.A significant area of activityin thearchitectural community that differentiates it from other technical committees occurs through the design and constructionofreal buildings tomeet design goals based on current understandings ofsound perception and propagation. Several case studiesofactual buildings that have been designed totest some of the emerging knowledge gained in the laboratory will be presented. 1:55 3pID2.Hot topics in acousticaloceanography. Lawrence A. Crum (Appl. Phys. Lab., Univ. of Washington,1013 N.E. 40th St., Seattle,WA 98105-6698) and MichaelJ. Buckingham(Scripps Inst. of Oceanogr.,La Jolla,CA 92093-0213) Sinceacoustical oceanography was given full TechnicalCommittee status within the ASA in November1991, there has been a rapiddevelopment of novel techniques forinterrogating theocean using sound. For example, the total global precipitation amount is poorlyknown; however, by examiningthe underwater noise produced by rainfall,it maybe possibleto useunderwater acoustic monitoringdevices toobtain an estimate of thisprecipitation and from that better estimates of the global heat flux. Recently, it has been demonstratedthatthe sound pulses can be propagated over extremely large distances in the ocean; consequently, a precise timing of thearrival of thesesound pulses over extended periods would enable changes in theaverage ocean temperature to be monitored, and thusprovide information on globalwarming. Similarly, ambient noise provides the basis of a newacoustic imaging technique, designatedacoustic daylight, that is analogoustoconventional photography butbased on sound rather than light. These and a variety of othertopics will be presented. 2:15 3pID3.Increasing the Acoustical Society's role in noisecontrol and noiseeffects. B. M. Brooks (P.O.Box 322, Vernon, CT 06066),T.J. Dubois (Tujunga, CA 91042), R.M. Hoover(Houston, TX 77082),G.C. Maling (Poughkeepsie, NY 12603), and L. C. Sutherland(Rancho Palos Vetdes, CA 90274) At themeeting of theTechnical Committee on Noiseat thefall 1991meeting of ASA in Houston,a discussionwas held on how, or if, theAcoustical Society should develop more concrete policies or actionconcerning noise control and noise effects. As a result of thatdiscussion, a Noise Task Group was formed by the authors atthe direction of theChair of theTechnical Committee toexplore theissues involved. Since that time, several special sessions have been held to helpestablish a direction for this activity. This talk will brieflyreview some of themore important elements of thatactivity which, properly, are beginning to involvemembers of other technicalcommittees within the Society in suchareas as hearing screening tests at ASA meetings, development of lecture materials for usein presentingtalks to youthon acoustics and noise, and potential development of room noise criteria and/or rating schemes for meetingspaces. Other such action areas that have evolved from these special sessions will bementioned. These offer other opportu- nitiesfor ASA membersto helpachieve a goalworthy of theSociety--to preserve quiet and tranquility in concertwith advances in technologyand population growth. WEDNESDAY AFTERNOON, 30 NOVEMBER 1994 PECOS ROOM, 1:00 TO 3:15 P.M. Session3pSA StructuralAcoustics and Vibration: Numericaland PhysicalExperimental Methods TakeruIgusa, Chair Civil EngineeringDepartment, Northwestern University, 2145 SheridanRoad, Evanston, Illinois 60208 ContributedPapers 1:00 beams,which is alsoused in ourexperimental studies. Results are obtained to discussfeatures such as pass/stopbands, modal density, and energy 3pSA1.Wave propagation in trussstructures. Yueping Guo (Dept.of sharingbetween different wave types. [Work supported by ONR.] OceanEng., MIT, Cambridge,MA 02139) A wave-basedapproach is usedto studytruss vibrations. Each truss 1:15 member is treatedas a wave-bearingsystem so that the numberof un- 3pSA2. Effect of mass loading on the dynamic behavior of a knowns is the same as the number of wave types, independentof the thr•e-dimensional truss. JosephE. Bondaryk and Ira Dyer (Dept. of physicaldimension and frequency.A global matrix systemis then formed Ocean Eng., MIT, 77 MassachusettsAve., Rm. 5-435, Cambridge,MA to solvethe overall problem, which, because of thewave approach used for 02139) the trussmembers, is very sparseand numericallyabsolutely stable. Thus even large-scaletrusses can be studiedwith computationthat is almost Recenttrends in submarinedesign suggest the useof trusslikestruc- trivial. An exampleis given for a trusswith 35 joints, connecting109 tures,connected to the hull by a limitednumber of attachmentpoints, to 3291 J. Acoust.Soc. Am., Vol. 96, No. 5, Pt, 2, November1994 128th Meeting:Acoustical Society of America 3291 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp supportrotating machinery and decks with passiveloads. The ratioof the tefial(Lama constants:/a•., Poisson relation o'--•0.5) and the liquid ma- supportedmass to thetruss mass is high,typically 5-10. Thisloading must terial (ix=0, 0'=0.5) are assumedto havelow compressibility,and the affectthe dynamicresponse of the truss.It is believedthat resiliently septaare rigid andweightless. Consequently, the boundarybetween the mountedmass will havea "fuzzy" effecton the trussand result in damp- cylinderand the septum'sradial displacementis absent,and the axial ing of structuralwaves. The MIT StructuralAcoustics Group is making displacementsare planar.The admittancematrix Y of the unit cylinderis experimentalmeasurements on a 1:15scale model of a nonpractical,3D, initiallyconstructed within a frameworkof the hypothesisof planecross submarinetress, constructed of 0.5-in. aluminumtubing, up to frequencies sections,neglecting strains induced by hydrostaticstress. Hydrostatic of 5 kHz. The dynamicresponse of two identicaltrusses, one unloaded and stresswaves are approximatelyincluded by adding to the unit cylinder one mass-loadedat a ratio of 5:1, to octave-bandnoise are measuredand admittancematrix correction AY associatedwith the strainsof hydrostatic compared.The resultsshow the effectsof passiveand resiliently mounted stressin the cylinder.Transfer matrix of the liquid-elasticwaveguide and massloading on a trussstructure. [Research supported by ONR.] its elements,expressed through the waveguidesections elastic parameters, havebeen obtained. It hasbeen shownthat dampingin a waveguidewith 1:30 a periodic structure is much greater in comparisonwith a regular waveguide,even when the latter is madewith a high-lossmaterial. 3pSA3. Influence of dynamic absorbers on a three.dimensional truss. Denis Branthonneand Ira Dyer (Dept. of Ocean Eng., MIT, 2:15 Cambridge,MA 02139) 3pSA6. On crack identificationand characterizationin a beam by The objectiveof this researchis to exploreexperimentally the effects nonlinear vibration analysis. Jeffry N. Sundermeyerand Richard L. of addingdynamic absorbers to a three-dimensionaltruss and to design Weaver (Dept.of Theor.and Appl. Mech., Univ. of Illinois,104 S. Wright analyticalmodels which predict the phenomena of attenuation.The trussis St., Urbana,IL 61801) built with cellsmade of aluminumrods and connectedin series.110 dy- namic absorbers are mounted on the rods in the center cell to achieve a The weakly nonlinearcharacter of a crackedvibrating beam is ex- local mass ratio of 3. The truss is excited at one end with white noise to ploitedfor the purposeof determiningcrack location, depth, and opening measurethe spatialattenuation averaged on octavebands as a functionof load.The approachis motivatedby examiningthe respooseof a bilinear axial distance.The data are comparedto the spatialattenuation for the spring-masssystem to excitationat two frequencies,such that the differ- undampedstructure. The differencesdetermine the effectof the dynamic encebetween the two frequenciesis the resonantfrequency of thesystem. absorbers.The overallshape of thedifferential curves of attenuationversus The numericallygenerated steady-state response of the systemclearly be- axial distanceis a step function,with the step locatedin the dynamic traysthe presence of thebilinear spring, even if thedifference between the absorbersattachment area. Assuming the equipartitionof energybetween compressiveand tensile stiffness is very small. The same idea is appliedto the differentwave typesand usingthe classicaltheory of attenuationof a crackedbeam forced at two frequencies,with thecrack providing a local wavespropagating on a semi-infiniterod loaded with a continuouslayer or bilinearstiffness in the beam.The numericallygenerated steady-state re- dynamicabsorbers, one predictsstronger attenuation than experimental sponseshows the effect of the openingand closingof the crack.The data at low frequencies.The assumptionof equipartitionof energyproves prominenceof this nonlineareffect is thencorrelated with crackposition to be incorrect and the applicability of the semi-infinite model is ques- anddepth. It is shownthat the nonlineareffect is maximizedif a staticload tioned.Subsequently, a new theory is derivedand validated by experiment is alsoplaced on the beamthat would cause the crackto be on the verge to describethe attenuationof waveson finite rodsloaded with a layer of of opening,thus determining the openingload. A perturbationanalysis is dynamicabsorbers. At low frequencies,this modelachieves a betteresti- appliedto the problem,and somepreliminary experimental results are mationof theaxial attenuation along the truss. [Work supported by ONR.] discussed.[Work supported by theArmy ResearchOffice.] 1:45 2:30 3pSA4. The effect of surface characterization and laser beams 3pSA7. A new method for damagedetection in structuresusing polarization on laser Doppler vibrometry. Ming Yang, Jacek transient bending wave propagation. K.-L. Ting and ZongaboLi Jarzynski,and Yves H. Berthelot (Schoolof Mech.Eng., Georgia Inst. of (Dept.of Mech.Eng., Tennessee Technol. Univ., Cookeville, TN 38505) Technol.,Atlanta, GA 30332) With theincreasing demand for safetyand reliability on structuresand In a laser Dopplervibrometry, the characterizationof the measured mechanicalsystems, damage detectionby nondestructiveevaluation surfaceplays an importantrole in bothin-plane and out-of-planesurface (NDE) methodshas attracted considerable attention from many research- motion measurements.Experimental data is presentedfor the in-plane ers. This paperpresents a new methodfor damagedetection based on optical probe configuration,where the vibratingsurface is illuminated time-frequencyanalysis of transientbending wave propagation. The wave- symmetricallyby two laserbeams. However, some of the conclusionsof let transformand short-time Fourier transform are applied to theanalysis the presentstudy apply alsoto out-of-planevibration measurements. It is of impulse-inducedbending wave propagationin a crackedfinite beam. found that certainsurfaces perform better than others.How the surface The time-frequencyrepresentation resulting from the transformationof characteraffects the in-planesurface motion measurement (in particular, measuredacceleration response is utilizedto identifythe reflection part of the signal-to-noiseratio and the probe alignment) is studied.The surfaces the transientbending wave by a crack and to determineits reflection studiedare lathe-finished,polished aluminum and steelsurfaces and two coefficientand the arrival time (from the location of the crack to the typesof retroreflectingtapes from 3M company.Also, the profilesof the transducerposition) for differentfrequency components contained in the metallicsurfaces are obtainedwith a profilometer.A simplemodel is used transientbending wave. The quantityof the crack is evaluatedfrom the to relatethe surfacecharacteristics to the performanceof in-planemotion reflectioncoefficient, and its location is estimatedfrom the arrival time. To measurement. The effect of polarization of the two laser beams is also demonstratethe effectivenessof the presentedmethod in quantifyingand studied,including the depolarizationof the light by the surface.[Work locating cracks, a cantilever beam and a free-free beam with the same supportedby ONR.] crack are investigated. 2:00 2:45 3pSAS. Dispersion of longitudinal waves in periodic septate 3pSA8. Changesin sound phenomenaof a beam due to rib and liquid-elastic waveguides. L. Shciba (EG&G WASC, Inc., 1396 weld properties. MatthewS. Carney,J. Adin Mann,III, andPatricia L. PiecardDr., Rockville,MD 20850) Driesch(Dept. of Aerosp.Eng. and Eng. Mech., Iowa State Univ., 2019 BlackEngineering, Ames, IA 50011) The propagationof longitudinalwaves in a compositeliquid-elastic waveguideis analyzed.The waveguide is a periodicstructure consisting of Experimentswill show how rib and weld discontinuitieson a beam alternatingliquid-elastic cylinders joined by rigid septa.The elasticma- effectwave propagationand far-fieldsound radiation. Numerous alumi- 3292 J. Acoust.Soc. Am., Vol. 96, No.5, Pt.2, November1994 128thMeeting: Acoustical Society of America 3292 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp hum andsteel beams were constructedusing a differentrib andweld Governingequations for wavepropagation of a thermoporoelasticplate configuration.The beamdimensions were 5 cmx 0.635 cm x 2.44 m and arederived. The materialobeys the theoryof Peckerand Dersiewicz [C. theribs had T-shaped cross sections of slightlyvarying dimensions. The Peckerand H. Dersiewicz,Acta Mech. 16, 45-64 (1973)].The tempera- beamswere then suspended and sound pressure 2.5 cm from the beam turesof solidand liquidphases are assumedto be different.Due to tem- surfacewas measured with a microphone.By changingthe physicalcon- peraturedifference in bothphases at everypoint in themedium, there is a structionof the attachmentarea of the ribsit waspossible to isolateand couplingparameter in heatconduction equations. The frequencyequation analyzethe effectsof the differentconstruction parameters. Also, the ex- istence and effect of residual stresses in the beams due to the construction is obtainedfor stress-freeand thermallyinsulated boundary conditions. processwas investigated. Analysis of the datashowed that both the ribs Numericalresults are calculated for isothermaland adiabatic wave propa- and the weldsproduced changes in the far-fieldsound radiation and the gationcorresponding to kerosenefilled sandstone. Phase velocities and the phasespeed of thepropagating waves. Also, the geometry and the means attenuationfactor are plottedagainst frequencies for symmetricand anti- of attachment of the rib affected the sound field. Transmission and reflec- symmetricmode. In an isothermalcase, the phasevelocity oscillates tioncoefficients were calculated, along with traveltimes of the waves,to sharplyfor thesymmetric mode but it is notso sharp for theantisymmetric verifythe changes in phasespeeds that were found. [Work supported by mode. But the behavior of the attenuation factor is reverse. In the adiabatic ONR, ContractNo. N00014-93-1-0493.] case,the phasevelocity oscillates very less,up to frequencyof 2 Hz; afterwards,it oscillatesfor both modes.In the attenuationfactor, there is 3:00 rapidoscillation throughout for the antisymmetricmode but it is lessin the 3pSA9. Wave propagationin thennoporoelasticplate. H. S. Paul symmetricmode. Oscillation is almostabsent between 2.5 and 4.5 Hz in andV. M. Murali (Dept.of Math.,Indian Inst. of Technol.,Madras 600 the symmetricmode. The phasevelocity is higherfor the isothermalcase 036, India) thanthe adiabaticcase whereas it is oppositefor the attenuationfactor. WEDNESDAY AFTERNOON, 30 NOVEMBER 1994 SAN MARCOS ROOM, 1:15 TO 3:00 P.M. Session3pSP SpeechCommunication: Auditory Front Ends for SpeechRecognition TerranceM. Nearey,Chair Departmentof Linguistics,42-32 AssiniboiaHall, Universityof Alberta,Edmonton, Alberta T6G 2E7, Canada Chair's lntroductio•l:15 ContributedPapers 1:20 M13 9PL,U.K.) and GuyBrown (Univ.of Sheffield,Sheffield S10 2TN, U.K.) 3pSP1. Recognitionof speech separated from acoustic mixtures. MartinCooke and Phil Green (Dept.of Cornput.Sci., Univ. of Sheffield, Recentlya computationalmodel of prosodyperception based on a 211 PortobelloSt., SheffieldS1 4DU, U.K.) multi-time-scaledecomposition of the outputfrom a cochlearmodel has beendemonstrated [Todd and Brown, "A multi-scaleauditory model of A perceptuallyplausible solution to the problemof automaticrecog- prosodicperception," Proceedings of theInternational Conference on Spo- nitionof speechin arbitrarynoise backgrounds involves computational kenLanguage Processing (1994)]. This model determines the temporal auditoryscene analysis (ASA) followedby recognitionof theseparated groupingand prominence of syllablesfrom a speechsignal. In thispaper patterns.However, it is notgenerally possible to recovera completerep- we presentevidence to showthat the model is ableto carryout a complete resentationof individualacoustic sources, so a newapproach is requiredto segmentationof a speechsignal, from the level of individualphoneroes recognizepartial descriptions.Suitable modifications to the powerfulsto- andphoneme clusters up to the phraseand utterance level. Implications for chasticframework of hiddenMarkov models (HMM) haverecently been speechrecognition are discussed. described[M.P. Cooke,P. D. Green,and M.D. Crawford,Proc. lnt. Conf. SpokenLanguage Processing (1994)]. The studiesreported here demon- strateHMM-based digit recognition in noise.An auditory-nervefiring rate 2:00 representationundergoes auditory scene analysis, producing a maskof time-frequencylocations where the speechis dominant.Each maskframe 3pSP3. Compositewavelet transform as an auditory model. Wade definesa marginaldistribution for the HMM probabilitycalculation. Re- Trappeand Joseph D. Lakey (Appl.Res. Labs., Univ. of Texasat Austin, suitsshow robustperformance even when the mask has most of its ele- P.O.Box 8029,Austin, TX 78713-8029and Dept. of Math.,Univ. of Texas mentsremoved. Further, these studies suggest a solutionto theproblem of at Austin,Austin, TX 78712) sensitivityto F0 in matchingauditory representations of speechin which F1 is representedby a set of resolvedharmonics. The new approach Motivatedby the humanauditory system, a new signaltransform is ensuresthat the matching process operates on a partialdescription consist- presentedwhich models the way humans hear. Cochlear processing acts ing largelyof harmonicpeaks. like a constantbandwidth bank of filtersin the low-frequencyrange but is of proportionalbandwidth at higher frequencies.This new transform, which we call the compositewavelet transform,is better able to model this 1:40 processthan standard signal processing techniques such as the short-time fourier transform(STFT) and the continuouswavelet transform(CWT). 3pSP2. A computational model of speech segmentation. Neil P. The compositewavelet transformin fact providesa signal analysistool McAngusTodd (Dept. of Psychol.,Univ. of Manchester,Manchester that is able to examinesignals with competingsignal structures whereas 3293 J. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128th Meeting:Acoustical Society of America 3293 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp the STFT and the CWT do not. Numerical results for this transform are Inst. der Univ. Goettingen,Buergerstr. 42-44, D-37073 Goettingen, presentedalong with a comparisonto theSTFT andthe CWT. Germany) 2:20 A multilevelneural network has been developed for the tasksof pay- 3pSP4. Modeling the separationof acousticalsignals based on the choacousticpreprocessing of speech, segmentation, segment classification, simulation of spike firing patterns. Kyrill A. Fischer (Drittes and recognition.Various neurophysiological and psychoacousticalresults Physikaliseheslust., Univ. of G6ttingen,B•rgerstrasse 42-44, D-37073 havebeen taken into account.The networkrelies heavily on uusupervised G•ttingan,Germany) learning.On increasingand nonlineartime scales,each level of the net- work extractssegments from the streamof input data and classifiesthem It is investigatedto whatextent the separationof overlappingacousti- cal soundsmay be achieved'by detectingand groupingcomodulated fre- usingtopology-conserving vector quuntizers (self-organizing feature maps quency•bands. Comodulation is defined by coherentenvelope fluctuations SOFlVl,"neural gas" algorithm(NGA) and passesthe resultsto the next which are detectedby meansof physiologicalmotivated algorithms in- level.Modified leaming algorithms for featuremaps have been developed volvingspike representation and coincidencedetection. Groups of co- to achievebetter representation of low-energetic consonants and transient modulatedfrequency bands are defined by clusteranalysis and their tem- partsin thefirst level. On higherleveh variantsof the NGA areused. The poralvariations are traced.Every group detected can then be separated segmentationalgorithm uses, depending on the level,the topologicaLrela- fromits "acousticalbackground" by suppressingall channelsnot belong- tioushipswithin the SOFM or statisticalinformation extracted from the ing to the givengroup. The paperaddresses problems concerning the training data. Within each segment,dynamic time normalizationis definitionof suppressiongain valuesand the problemof overlapping achievedby appropriatetemporal integration. The outputof the topmost groups. level is passedto a recognitionnetwork containing a linguisticmodel to 2:40 performcontinuous speech recognition. Results using this purely neural 3pSPS. Processingof continuousspeech by a hierarchical neural andin many parts self-organizing method will be presented and compared network. Wolf DieterBrandt and Holger Behme (DrittesPhysikalisches to classicalmethods. [Work supported by BlvlFr.] WEDNESDAY AFTERNOON, 30 NOVEMBER 1994 BALLROOM B, 1:30 TO 3:00 P.M. Session3pUW Underwater Acoustics:Signal ProcessingI: Matched Field Homer P. Bucker, Chair Naval Commandand ControlOcean Surveillance Center, San Diego, California 92152-5001 ContributedPapers 1:30 nonuniformspeed due to environmentalmismatch. We showthat by al- lowingfor theserandom perturbations in sourcemotion, an improvement 3pUW1. Calculation of a source spectrum using matched-field in the localization results is obtained. tracking. HomerBucker (Code541, NRaD, NCCOSC, San Diego, CA 92152) An underwateraCOustic source can be detected by findingthe best match between a measured set of covariance matrix elements and those 3pUW3. Environmental source tracking using measured and calculatedfor possibletracks [H. Bucker,"Matched-field tracking in shal- modeled replicas. Iohn S. Perkins, Laurie T. Fialkowski, Michael D. low water,"L Acoust.Soc. Am. (to be published)].Let (grit) be the Collins,W. A. Kuperman,a)Timothy L. Krout,Jon Jannucci (Naval Res. measuredelements and (•'t[t) be the elements calculated for the best track Lab., Washington,DC 20375), RossF. Barrett, L J. Kelly, Ashley of a unit source.Here, index! refersto a pair of sensors,f to a frequency Larsson (Defence Sci. and Technol. Organization,Salisbury, SA, bin,and t isfor different times. Then a plotofS(f,t)=Y•tgtft/Zt•tl , is a Australia), LindsayHall (DefenceSci. Establishment,Auckland, New Lofargramin whichthe effectsof the multipathpropagation have, at least Zealand), JohnA. Fawcett,and AnthonyHoffmann (DefenceRes. in part,been removed. Of course,the success of thedeconvolution depends EstablishmentPacific, Victoria, BC, Canada) uponthe accuracyof the propagationmodel and contaminationof other Preliminaryresults will be presentedfor the second7TCP Environ- soundsources. Several examples will be presentedto illustratethe method. mentalSignal Processing Exercise (TESPEX 2), whichwas conducted in June 1994 in shallow waters north of Darwin, Australia.There were two 1:45 objectives:(1) demonstrateimprovements in environmentalsourc.• track- 3pUW2. Exploiting source dynamics in matched-field processing. ing [Collinseta!., L Acoust.Soc. Am. 94, 3335 (1993)] (a single- Zoi-HeleniMichalopoulou and Michael B. Porter (Dept.of Math. and frequency,single-hydrophone synthetic-aperture tracking technique) by re- Ctr. for Appl. Math. and Statistics,New JerseyIust. of Technol.,Newark, lyingon a second,horizontally separated hydrophone, and (2) determine NJ 07102) the horizontalresolution the environmentprovides to a vertical array throughmatched-field processing [Perkins and Kuperman, L Acoust.Soc. Matched-fieldprocessing is typicallyconsidered as a staticproblem of Am.87, 1553 (1990)]. The approach was to first characterize theregion by locatinga fixed,narrow-band source. However, the source does not ran- towinga high-SNRsource throughout the region and measure the replica domlyjump from point to pointduring the course of timeand much can be fieldsusing two verticalline arraysseparated by severalkilometers (one gainedby exploitingthis extra information.Various schemes have been with 32 elements,the other 4 elements),and then to use this data to form proposedin the pastfor treatingsource motion. A key problemis that even the replicasneeded to track the sourceas it traversedthe regionalone a when the source motion is uniform the source may appear to have a variety of tracks.The measuredreplicas are supplementedby modeled 3294 J.Acoust. Soc. Am., Vol. 96, No.5, Pt.2, November1994 128th Meeting:Acoustical Society of America 3294 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp replicas;the environment used in themodeling is determinedby inverting density.The geometricparameters consist of sourceand arraysensor po- the measureddata. We presentpreliminary processing results relevant to sitions.In manysituations it is assumedthat the arraysensor positions are both objectives,including environmental inversions and trackingwith knownand in thesecases it is importantto the inversionprocess that the measuredand modeled replicas. aYrescut address: Scripps Institution of arraysensor positions are knownprecisely. In thispaper an acousticnavi- Oceanography,La Jolla,CA 92093. gationmethod for preciselydetermining sensor position is presented. Acoustictravel time measurements were used to navigatethe sensors of a 2:15 94-m verticalarray in shallowwater (130 m). Army navigationperfor- mancewas evaluated during a verticalarray deployment in the Mediter- 3pUW4. Performance stability of broadband matched-field ranean from the RN Alliance. A network of four bottom-moored acoustic processorssubjected to sound speed and array-elementlocation transponderswere interrogatedfrom the Alliance and their replieswere error in a shallow-waterenvironment. HowardA. Chandler,Murty receivedby the verticalarray sensors and telemeteredto theAlliance and Akundi,and O. B. Smith (Naval Res.Lab., StennisSpace Center, MS theirreplies were received by thevertical array sensors and telemetered to 39529-5004) the Alliancefor navigationprocessing. In October,over a 2-day period, currentversus depth and array shape was monitored. During this period the The effectsof array-elementlocation errors on the performanceof the local currentswere small; the array shape was estimatedto be almost threebroadband matched-field processing algorithms (Bartlett, maximum straightand nearly vertical. likelihood,and sectorfocusing) have been investigated. The KRAKEN propagationmodel was used to generatethe replica acoustic pressure field 2:45 at multiplefrequencies for a shallow-waterchannel with a depthvariable sound-speedprofile typical of a midlatitudesummer environment. It was 3ptlW6. Matched beam processingfor geeacousticinversion of also used to simulate a "detected" field due to an acoustic source in the bottom sonnd-speedprofiles. T. C. Yang (Naval Res. Lab., presenceof bothuncorrelated and correlated(modal) noise. These fields Washington,DC 20375)and T. Yates (VectorResearch Co., Rockville, were then correlatedusing the three algorithmsfor selecteddegrees of MD 20852) soundspeed and array deformation error. Results will be presented.[Work sponsoredby the Office of Naval Research,Program Element 61153N, A broadbandsignal (shot) received on a verticalarray was processed with technicalmanagement provided by NRL-SSC.] for geeacousticinversion of bottomsound-speed profile. The data were beamformedto showthe distributionof waterborneand bottom interacting signals.By correlatingthe (complex)beams containing the bottom inter- 2:30 actingsignals with the equivalentlyformed beams for the replicafield (matchedbeam processing), one evaluatesthe ambiguityfunction maxi- 3pUWS. Acousticarray navigationin shallowwater. D. E Gingras, L. Troiano (SACLANT UnderseaRes. Ctr., Viale San Bartolomco,400, mumat the sourcelocation and searches for the bottomsound-speed pro- 19038La Spezia,Italy), and R.B. Williams (NavalCtr. for Command, file whichyields the highest correlation for the matchedbeam processing. Differentfrequency hands of the signalare investigatedto evaluatethe Control,and Ocean Surveillance, San Diego, CA) sensitivityto bottomsound-speed variations. The invertedsound-speed The inversion of acoustic field data for estimation of unknown envi- profilesare found consistent (within the resolution of 50-100 m/s)with the ronmentalor geometricparameters is receivingconsiderable attention. The sound-speedprofiles estimated from (1) coresamples and other geoacous- environmentalparameters usually consist of bathymetry,sound speed in tic dataat the site,and (2) the arrivaltime of the Headwaves [J. Wolf, J. the water, and bottomproperties such as soundspeed, attenuation, and Acoust.Sec. Am. 94, 1769 (1993)]. WEDNESDAY AFTE•OON, 30 NOVEMBER 1994 BALLROOM A, 3:30 TO 5:30 P.M. Plenary Session,Business Meeting, and Awards Ceremony Jiri Tichy, Chair President,Acoustical Society of America BusinessMeeting Presentationof certificatesto New Fellowsand ScienceWriting Award recipients Presentation of Awards DistinguishedService Citation to William J. Cavanaugh Silver Medal in Noise to Kenneth M. Eldred Silver Medal in PhysicalAcoustics to Julian D. Maynard Silver Medal in SpeechCommunication to PeterLadefoged Electronicmusic performance presented by HueyonKim Lentand Keith Lent 3295 J. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November 1994 128th Meeting:Acoustical Society of America 3295 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp THURSDAY MORNING, 1 DECEMBER1994 SABINE ROOM, 8:00 A.M. TO 12:00NOON Session 4aAB Animal Bioacoustics:Animal BioacousticsResearch Methodology I Whitlow W. L. Au, Chair Hawaii Instituteof Marine Biology,PO. Box 1106,Kailua, Hawaii 96734 Chair's Introductions8:00 Invited Papers 8:05 4nAB1.A novelmechanism for directionalhearing in a parasitoidfly. D. Robert,R. R. Hoy (Sec.of Neurobiol.and Behavior, CornellUniv., Ithaca, NY 14853-2702),and R.N. Miles (StateUniv. of New York,Binghamton, NY 13902-6000) Soundlocalization is a basicbehavioral task of the auditorysystem. Incident sound waves a.n'ive at theears and generate interaural differencesin timeof arrivaland in amplitudethat are key cuesfor the computationof sounddirection. In smallanimals, both cues canbecome vanishingly small, posing a challengefor directionalhearing. Yet nearlyall animalsthat hear can localize sound. In the fly Ormiaochracea, the two acousticsensors are separated by onlyabout 520/•m, andare contained within an undividedair-filled chamber,an arrangement that results in minimaldifferences in interaural time (<2 pa) andno intensity cues from an incident sound wave.Using laser vibrometry, it is shownthat the mechanicalresponse of the tympanalmembranes has a pronounceddirectional sensitivity.Using probemicrophones and neurophysiologicalrecording techniques, it is demonstratedthat this fly utilizesa novel mechanismfor thedetection of an incidentsound wave. This mechanismrelies on the mechanicalcoupling between the two tyropanel membranes.In effect,the fiy's earsoperate by mechanicalpreprocessing, converting interaural acoustic time differences of 2 msor less into neuraltime differenceslarge enoughto encodein the centralnervous system. 8:30 4nAB2. Seismiccommunication in amphibians. PeterM. Narins (Dept.of Biol., UCLA, 405 HilgardAve., LosAngeles, CA 900•) The white-lippedfrog, œeptodactylus albilabris, exhibits the greatestsensitivity to substrate-bornevibrations (seismic stimuli) reportedto datefor any terrestrialanimal. Nerve fibers from the saceulus,the sourceof this extraordinarysensitivity, show clear responsestosinusoidal seismic stimuli with peak accelerations lessthan 0.001 cm/s 2.In addition,this animal generates substrate-borne vibrationalsignals during calling. As the male'svocal sac expands, it strikesthe substrateimpulsively, generating a verticallypolarized surface(Rayleigh) wave that is detectedby neighboringmales. These Rayleigh waves are used as intraspocific communication signals to coordinatechorus behavior in thisspecies. Recently, a particularlyunusual behavior has been described for onespecies of Malaysian treefrog(Polypedates). During nocturnal courtship, females living in densemats of floatingvegetation perch conspicuously on a reed or bladeof grassand tap theirrear toes rhythmically. Males on neighboringreeds were observedto quicklylocate and mate with the tappingfemale. Thus it is likelythat toe tapping functions as a vibrationalsignal indicating the female's presence to neighboringmales. It is becomingclear that seismic communication and sensitivity to wbole-bodyvibrations are moreubiquitous among the vertebrates thanhad been previously imagined. [Work supported by NIH.] 8:55 4nAB3. Studyingthe evolutionaryhistory of communication:The ghostof signalspast. MichaelJ. Ryan (Dept.of Zool., Univ. of Texas,Austin, TX 78712) The efficiencyof communicationcan be maximizedby a tight matchbetween signs! and receiver. This view underliesthe field of animalcommunication and has led biologiststo proposefunctional and evolutionary models that are firmly groundedin suchlinkage. Recentempirical studieshave shown, however,that tight linkage betweensender and receiverneed not be the case. Using the phonotacticresponse of female•rogs to variationin matingcalls, it hasbeen shown that some aspects of the receiverare quitebroad relativeto the conspecificsignal. For example,females show preferences for signalsof their own speciesto whichare added componentsfrom the signals of otherspecies. Also, using algorithms for reconstrnetionof ancestral traits, it is shownthat key stimuli neededfor species-specificpattern recognition have not beentightly linked with receiverevolution. These studies suggest a more liberal interpretationfor the evolutionof animalcommunication systems. 9:20 4nAB4. Effects of aircraft noiseon wildlife: Techniquesused in Air Force research. RobertC. Kull (AL/OEBN, 2610 Seventh St., Wright-PattersonAFB, OH 45433-7901) Manyresearchers have set out to studythe effects of noiseon animals,especially aircraft noise, for thepast 20 yearsyet have failed in properlydescribing the noisetheir subject animals were exposedto. In 1989 the Air Forcebegan a seriesof wildlife studiesto determinethe effects of aircraftnoise. Research included effects on DesertBighorn Sheep, caribou, kit fox,domestic turkeys, dairy cows,horses, and raptors. One major objective in thesestudies was to accuratelydetermine the noise exposure levels from aircraft. 3296 J. Acoust.Soc. Am., Vol. 96, No.5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3296 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp Conventionalmethods were used for researchon domestic animals, but studies on wild animals posed special problems. Various techniquesand procedures of hownoise exposures were determined will be described. 9:45 4aABS.Physiological monitoring of noiseeffects in wildlife.D.W. DcYoung (Univ. Animal Care, Univ. of Arizona, Tucson, AZ 85724)and R.C. Kull,Jr. (AL/OEBN,Wright-Patterson Air Force Base, OH 45433-7901) Noiseas a stressto animalswill bediscussed with respect to thephysiological parameters that characterize it. Known currently availableradiotelemetry systems that can monitor some of theseparameters will be presented. Data that can be reliably derived from parametersobtained by availableradiotelemetry systems will be presented.Possible pathology due to long-termstress as well as informationfor animalstudies, telemetry implant surgery and anesthesia, and the potential complications of implant surgery will be discussed.Finally, recommendations for future study of noiseas a stressorto animalswill bemade. [Work supported by USA.F.] 10:05-10:15 Break 10:15 4aAB6.Passive acoustic localization of callinganimals in 3-D space.John L. Spiesberger(Dept. of IVletcorol.and the Appl. Res. Lab.,512 Walker Bldg., Penn State Univ., University Park, PA 16802} Fluctuationsand uncertainties in winds (currents) and sound speed place lower limits on the accuracy with which calling animals canbe passivelylocalized from their calls in terrestrialand marine environments. The most accurate acoustic passive localizations of animalsrequire simultaneous mapping of theseenvironmental fluctuations using tomographic techniques [J. Spiesbergerand K. Fristmp,Am. Nat. 135, 107-153 (1990)]. One localization experiment conducted in a woodfound tomographic localization of a cap gunpossible but tomog•aphic localization of birds difficult because of echoes.Marine environments may be conducive totomographic localizationsbecause of a paucityof reflectingsurfaces atlow frequencies. A new oceanographic instrument called a surfacesuspended acousticreceiver (SSAR) has the potential for passively localizing and censusing calling animals throughout the world's oceans in real time.[Work partially supported by AdvancedResearch Projects Agency.] 10:35 4aAB7.Using FFr spectrumanalyzers to measureanimal sounds. Frank T. Awbrey (Biol.Dept., San Diego State Univ., San Diego,CA 92182-0057) Sound-pressurelevels of animalsounds have been measured in so manydifferent ways that comparison between studies is very nearlyimpossible. The transient,repetitive nature of mostvocalizations means that standard sound level metersmay yieldvery differentnumbers, depending on metertime constant and frequency weighting. Integrating sound level meters, which average sound overvarious periods and measure sound exposure level directly, are an improvement,but are hard to usefor measuringsingle, transient soundssuch as a frogcall or an echolocationpulse. A betterway, with briefsignals, is to recordthem through calibrated transducers, alongwith calibration tones of knownamplitude, onto tape recorders with linear response to varyinglevels. These recordings can then bemeasured with digital spectrum analyzers in a waythat is reliable,accurate, and repeatable. Possible measures include peak, octave, one-thirdoctave, maximum, time-average, sound exposure, and spectrum levels. Comparability requires attention to andreporting of importantdetails, such as averagingtimes, filter bandwidth and weighting functions, and adherence to standardsfor measuringand reportingsound. 10:55 4aABS.Determining the effectsof low-frequencysound on the fishauditory system. MardiC. Hastings,James J. Finneran (Dept.of Mech.Eng., Ohio State Univ., 206 W. 18thAve., Columbus, OH 43210), ArthurN. Popper,and Pamela J. Lanford(Univ. of Maryland,College Park, MD) A 15-m-longflexible waveguide was successfully used to createa travelingwave for frequenciesbelow 300 Hz in water.A cylindricalwaveguide that allows only plane-wave propagation was designed and fabricated from Plexiglas. This flexiblematerial reducedthe effective stiffness and thus the sonic speed and wavelength of thedisturbance generated by a J9 underwatersound projector rangedto oneend. In addition,the energy of thewave was dissipated as it traveledalong the waveguide; consequently, little if any reflectionoccurred at itsend. The fish were placed inside a PVCmesh cage and positioned in thewaveguide approximately 3 m down fromthe J9. Then they were exposed to eithera continuouswave or a pulsedwave similar to manmadesources. Afterwards the fish wereheld for a specifiedtime period and then sacrificed. The auditoryorgans were treated with fixativeand removed. Then they were shippedovernight to theUniversity of Marylandwhere the tissue was immediately prepared for scanningelectron microscopy to determineif sensory hair cells had been destroyed. This method has yielded dependable data to help assess the effects of low-frequency soundon hearing in fish.[Work supported by ONR.] Contributed Papers !1:15 NationalPark in Namibiaduring the late dry season.Meteorological mea- surementsshow that strongtemperature inversions form at the surface 4aAB9.Abiotic controls on elephantcommunication. David Larom, beforesunset and decaywith sunrise,often accompanied by calmwind MichaelGarstang (Dept. of Environmental$ci., Univ. of Virginia, Charlottesville,VA 22903), RichardRasper (Univ. of Mississippi, conditionsduring the early evening.These observationsare used in an Unlv•r•ity,M8 38677),and Malan LinOeque(Etosha Ecological acousticmodel to determinethe sendtivityof infi'a•oundto the effectsof Institute,Namibia, Africa) (a) thestrength, thickness, and elevation of temperatureinversions, and (b) the growth and decayof an inversiontypical of dry, elevatedAfrican Atmosphericconditions conducive to long-range transmission of low- savannas.The resultssuggest that elephantcommunication range more frequencysound as used by elephantsare found to existin theEtosha than doublesat night. Optimumconditions occur 1-2 h after sunseton 3297 J. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3297 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp clear,relatively cold, calm nights. At thesetimes ranges of over 10 km are 11:45 likely,with greatestamplification occurring at the lowestfrequency tested. 4aABll. A publicly accessibledatabase for marine mammal call This strongdiurnal cycle in communicationrange may be reflectedin longerperiod changes in weatherand may exert a significantinfluence on classificationresearch. David K. Mellinger and ChristopherW. Clark elephantbehavior on time scalesfrom daysto many years. (Bioacoust.Res. Prog., Cornell Univ., 159 SapsuckerWoods Rd., Ithaca, NY 14850) A centralproblem in bioacoustictransient (animal sound) detection and 11:30 classificationhas been the lack of standardsagainst which to compare variousmethods. A similarproblem existed in speechrecognition research; 4aAB10. Applications of multifrequency acoustics:Spatial patterns it was solvedby the creationof databases(e.g., TIMIT) usedas common in a freshwater lake. C.F. Greenlaw,R. W. Player,and U.S. Samilo datasources for testingand comparingdifferent methods. A similardata- (TracorAppl. Sci., Inc., 9150 ChesapeakeDr., SanDiego, CA 92123) base has been initiated for use in marine mammal sound detection and Verticalprofiles of acousticalscattering at four frequencieswere ob- classification.Initially, mysticeresounds have been placed in the database; tainedat a meshof pointscovering the majorregions of a small,manmade sincetheir low frequencymakes possible a low samplingrate, a large freshwater lake. Inversion methods were used to estimate size-abundance numberof soundsmay be storedin the spaceavailable. The database profiles of zooplanktersusing a scatteringmodel validatedfor oceanic currentlyholds soundsof four speciesof mysticere--1765blue, 3909 zooplanktonsuch as copepods.These profileswere then used to form finback,356 minke,and 589 bowheadwhale vocalizations--atsampling estimatesof lake-wide3-D spatialpatterns sorted by size classesof the ratesfrom 100 Hz to 2 kHz. It wasdesired to categorizesounds by signal- dominant zooplankters.Results illustrate the value of multifrequency to-noiseratio, since performance of detectionmethods will dependon this; acousticalsurveys as an adjunctto conventionalsampling for rapidassess- sinceno measureof SNR for transientsignals is well known,a simple mentof spatialdistributional features of zooplanktonpopulations in lakes. measureof energyratio within the sounds'frequency band was used.The Problemswith applicationsof ocean-basedassessment techniques to lacus- databaseincludes performance data of some detectionmethods, and it is trine environments,such as the lack of validatedscattering models for hopedthat other researchers will contributeboth sounds and performance freshwaterzooplankton, are discussed. data.The databaseis accessibleat ftp.ornith.cornell.edu. THURSDAY MORNING, i DECEMBER 1994 SAN ANTONIO ROOM, 8:30 TO 11:45 A.M. Session 4aEA Engineering Acoustics:Piezocomposite Transducers Thomas R. Howarth, Chair Naval ResearchLaboratory, Underwater Sound Reference Detachment, P.O. Box 568337, Orlando,Florida 32856-8337 Invited Papers 8:30 4aEA1. Developmentof 0-3 piezocompositetransducers for underwater applications. Fred G. Geil and Linda L. Matteson (WestinghouseElectric Corp., Oceanic Div., Annapolis, MD 21404) Piezorubberis a compositematerial consisting of leadtitanate powder dispersed in a neoprenerubber matrix. Piezorubber has certainacoustic properties that sets this transruction material apart from the traditional ceramics. Among these are some good qualities suchas a highhydrostatic sensitivity, a relatively low lateralsensitivity, high resistance to shock,and conformability. Some less attractivequalities are the low dielectricconstant and high density.Nevertheless, piezorubber has been the materialof choicefor severalUS Navyprojects. These include a hydrophoneflank array for ASW, a high-frequencyarray of smallelements, a 700-element widebandwidth listening array, a conformalshell-mounted low-frequency hydrophone, a continuous element for towedarrays, and high-frequencyelements for side-lookingsonors. These six projectswill be describedbriefly, concentrating on theachieved benefits andwhat has been learned about applying piezornbber to hydrophoneapplications, also indicating the areas where the application was lessthan completely successful. 9:00 4aEA2. U.S. Navy 0-3 piezocompositetransducers. Mark L. Pecoraro (Naval Res. Lab., UnderwaterSound Reference Detachment,P.O. Box 568337,Orlando, FL 32856-8337) Interestin 0-3 piezoelectriccomposite materials for usein hydrophoneapplications has grown considerably in recent years. Designswhich require operation in thehydrostatic mode with a largehydrostatic voltage coefficient gh, aredesired to increase free-fieldvoltage sensitivity and meet the ever increasing demands placed on hydrophoneperformance. U.S. Navy scientists at the NavalResearch Laboratory, Underwater Sound Reference Detachment, have investigated the utilization of 0-3 piezocompositefor sonarapplications and have developed various hydrophone configurations based on specific program requirements. The requirements of theprograms, such as a lightweight,low-profile, and high receive sensitivity, demanded unique designs and the need for utilizing theunique characteristics of 0-3 compositematerials. The hydrophones presented in this discussion used a 0-3 compositeknown at NRLsimply as piezorubber orPZR. This material consists of leadtitanate particles embedded in a neopreneelastomeric matrix. This discussionwill coverthe development, including problems and solutions, fabrication, and testing of twounique 0-3 composite hydrophones. 3298 d.Acoust. Soc. Am., Vol. 96, No. 5, Pt.2, November1994 128thMeeting: Acoustical Society of America 3298 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 9:30 4aEA3.Development of 1-3 and 2-2 piezocompositetransducers. Leslie Bowen, Richard Gentilman, Hong Pham, William Serwatka,and Daniel Fiore (Mater.Syst., inc., 521 GreatRd., Littleton,MA 01460) 1-3 and2-2 piezoelectricceramic/polymer composites offer design versatility and performance advantages over monolithic piezoelectricceramic and monolithic piezoelectric polymer devices in bothresonant and nonresonant transducer applications. Re- cently,a newprocess, viz., ceramic injection molding, has been applied to solve the difficulties of cost-effectivelymanufacturing the arraysof fine PZT ceramicelements required for compositetransducer assembly. As a result,these materials are nowavailable in commercialquantities for thefirst time. In thispaper, Materials Systems, Inc. briefly introduces its PZTceramic injection molding transducermanufacturing process, and then reviews the performance of various 1-3 compositetransducer designs as a functionof compositelayout, materials, and transducer performance enhancement features, such as stiff cover plates and Poisson's ratio alecou- pling.The performanceof severaltransducer designs in bothnonresonant sensing and actuating undersea applications, and in high-frequencyresonant applications, e.g., acoustic imaging, is discussed.[Work supported by ONR.] 10:00 4aEA4.1-3 Piezocompositetransducer materials for commercialunderwater applications. Victor Murray (Fugro-UDI Ltd., Bridgeof Don,Aberdeen, Scotland AB23 8JW,United Kingdom) Fugro•UDILimited has gained several years experience in developingpiezo-composite materials for usein underwaterimaging sonarsoperating in thefrequency range 100-500 kHz. A substantialamount of thiswork has concentrated onmultielement arrays for militaryapplications such as mine counter measures. The low mechanicalquality factor (Q,,) andhigh electro-mechanical coupling coefficient(K•) of the materialhas providedwideband and efficienttransducer materials. These parameters and otherssuch as dielectricconstant and electrical impedance can be tailoredby varyingthe type and quality of boththe ceramic material and polymer phasewithin the piezocomposite device. This has contributed to reducingthe development and manufacturing costs of piezocomposite transducers.This presentation will discussthe various transducers developed by Fugro-UDIfor commercialapplications ranging from simpleecho-sounder transducers, to sidescan transducers, through to multielementarrays for electronicallyscanned sonars. Sensitivi- tiesand beam patterns for piezocompositedevices will be comparedwith theirceramic counterparts. Other important transducer parameterssuch as pressureand temperaturedependence of the piczocompositcmaterials will be presented. 10:30 4aEA5.Evaluations of 1-3 piezocompositetransducers for underwaterapplications. Robert Y. Tingand Thomas R. Howarth (NavalRes. Lab., Underwater Sound Reference Detachment, P.O. Box 568337,Orlando, FL 3;'856-8337) This presentationbegins with discussionson 1-3 piezocompositetransducer designs and how the designsmay be tailoredfor specificunderwater acoustic applications. For instance,1-3 piezocompositematerials with cover plates for actuatorapplications shall be shownand compared with other 1-3 piezocompositetransducers that feature finer scale piezoceramic rods for widebandunderwater acousticimaging applications. Other 1-3 piezocompositetransducers to be showninclude multilayer plates with elementsstacked in mechanicalseries and wired electrically in parallelas well as monolithicstructure designs with elementsetched into the piezocom- positestructure. Underwater electroacoustic evaluations of eachof the 1-3 piezocompositetransducers will be presented.The in-water measurementsinclude the transmittingand receivingperformances as well as directivitypatterns over extendedfrequency bands. Discussionson how the 1-3 piezocompositetransducers may be appliedtowards future underwater acoustic systems shall conclude thepresentation. [Work sponsored by ONR.] ContributedPapers 11:00 Piezoelectriccomposite materials are increasinglyused in medicaland otherultrasonic transducers. In orderto designcomposite transducers with 4aEA6. Surface-mounted sensors on a large-area 1-3 composite desirableperformance, especially in high-frequencyrange where polymer actuator. Robert D. Corsaroand Brian Houston (Naval Res. Lab., Code and ceramicstructures are not much smallerthan wavelength,a good 7130, Washington,DC 20375-5350) understandingof dynamicbehavior of thematerial is necessary.This work Surface-mountedsensors can be usedto monitorthe performance of an developeda dynamicmodel to investigatewave propagationalong thick- underwateracoustic projector, or to controlits impedancein a complex nessdirection and resonantbehavior of the transducer.Relationships of dynamicenvironment. However, there are few examplesin theliterature of thicknessresonant frequencies as well aslateral periodic resonant frequen- studiesof the issuesinvolved in marryingsensors and actuators.These cies with compositeconfiguration and material(polymer and ceramic) issuesinclude spatial sampling, near field sensing,internal resonances, and propertieswere emphasized.Discussions on couplingcoefficient k• of bothdirect and extraneous coupling mechanisms, all of whichcan contrib- transducersas a functionof volumefraction and aspectratio of composite ute to complicatethe systemtransfer functions and limit the applicability are presented.A seriesof compositetransducers with varied parameters of thisapproach. The work presentedhere includes measurements made on were fabricatedand measured.Experimental results of k t and resonant a 1-3 compositeactuator with integratedpressure and velocity sensor frequenciesare comparedwith the theory. layers.Both free-fieldsensitivities and actuator-sensorcoupling transfer functionsare evaluatedin the NRL Large Pool Facility.These are com- 11:30 paredwith predictionsfrom simple acoustic models. Implications for local control of the actuator's surface are also discussed. 4aEA8. 1-3 compositetransducer for partial dischargedetection in high-voltagetransformers. Valsala Kumsingal (Ctr. for Mater. 11:15 Technol.,Univ. of Technol.,P.O. Box 123, Broadway,NSW 2007, Australia) 4aEA7. A dynamic model for piezoelectric composite transducers and couplingcoefficient k t. YonganShui (Inst. of Acoust.,Nanjing Ultrasonictechniques alone or in combinationwith electricalmethods Univ., Nanjing 210008, People'sRepublic of China) and Qiang Xue are increasinglybeing used for the detectionand/or locationof partial (AnnlogicCorp., Peabody,MA 01960) discharge(PD) in high-voltagetransformers and other electricalplants. 3299 J. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November 1994 128th Meeting:Acoustical Society of America 3299 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp Ultrasonictransducers used for fault location are traditionallycoupled mechanical vibrations as well inside the transformer. The authors has de- externallyon to the transformerwall. Mountingtransducers inside the veloped1-3 piezopolymercomposite transducers which are capableof transformersteel tank has certaindefinite advantages like better noise operatingin thisadverse environment. These transducers were life testedin immunity,increased sensitivity due to betteracoustic matching to oil, and mineraloil at 130 øC for over500 daysand their k t valuesmonitored as a lesscomplicated signals (only longitudinal waves). Transformers are filled function of time. Life test and vibration test data for several transducers as wilh mineraloil whosetemperature could rise up to 110øC during normal well as sensitivity,frequency response, pulse widlh, and constractional operation.Also, there are largeelectric and magnetic fields and strong detailsare presented. THURSDAY MORNING, 1 DECEMBER 1994 BOSQUE ROOM, 8:15 TO 10:20 A.M. Session 4aMUa Musical Acoustics: General Topics Uwe J. Hansen, Chair PhysicsDepartment, Indiana State University,Terre Haute, Indiana 47809 Chair's lntroduction---8:15 ContributedPapers 8:20 8:50 4aMUal. A study of lip vibrations in a trombone. David C. CopIcy 4aMUa3. On the use of Schr•dinger's equation in the analytic andWilliam J. Strong (Dept.of Phys.and Astmn., Brigham Young Univ., determination of horn reflectance. David Berners and Julius O. Provo,LIT 84602) Smith,Ill (Ctr. for Cornput.Res. in Music andAcoust., Dept. of Music, StanfordUniv., Stanford,CA 94305-8180) More than50 yearsago, Martin investigated lip vibrationsin a coronet The flaringhorn has traditionally been modeled in onedimension using mouthpieceusing stroboscopic photography [D. Martin,J. Aconst.Soc. piecewiseconical or cylindricalelements. Acoustic properties within each Am. 13, 305-307 (1942)].Since then, several researchers have based lip element are known, and scatteringbetween the elementsis computed. modelson Martin's data.Unfortunately, due to the qualityof the photo- Under the piecewisemodel, a shapefor the wavefrontof the acoustic graphs,it is difficultto obtainanything more than a limitedquantitative disturbancewitMn the hornis implicitlyassumed (planar for cylindrical descriptionof the lip motion.The purposeof thisstudy is to obtainmore elements,spherical for conicalelements). For hornsof significantflare, the detailedphotographic sequences and lip motiondata on whichnew models true wavefrontshape will be neitherplanar nor spherical.A more general maybe based.The trombonewas selected as representativeof the lip reed modelis thusdesirable. Here an alternatemodel is presented:The flaring family.A computer-controlledfiber optic stroboscope was used to capture horn is modeledaccording to Webster'sequation. A changeof variables the motionof a player'slips on video. By insertingthe optic bundle transformsthe equationinto the form of the Schrrdingerwave equation throughsmall holesdrilled in the mouthpiece,lip motionwas observed usingin one-dimenaionalparticle scattering. Boundary conditions can be fromthe frontand side for six notes(Bb2, F3, Bb3, D4, F4, G4) played deriveddirectly from the physicaldimensions of the horn,and the solution at loudand soft dynamic levels. Video sequences and resulting lip motion of theequation gives estimates of acousticproperties in termsof frequency datawill be presentedand discussed. dependentreflection and transmission coeffÉcients. Here, Webster's equa- tion is solvedalong the entirelength of the horn,with no lumpedscatter- ing.Advantages over piecewise modeling techniques include the abilityto 8:35 specifyarbitrary axisymmetric wavefront shapes for the acousticdistur- bance within the horn. Under appropriateassumptions for wavefront 4aMUa2. Brass soundsimulation with a lip vibration model having shapes,results converge to thoseobtained with traditionalpiecewise mod- twodegrees of freedom. SeijiAdachi and Masa-aki Sato (ATRHuman els. informationProcessing Res. Labs., 2-2 Hikaridai,Seika-cho, Soraku-gun, Kyoto619-02, Japan) 9:05 Brass sound simulation is carried out with the use of a two-dimensional 4aMUa4. The wave digital hammer: A computationallyefficient lip vibrationmodel, where lips executeboth rolling and reciprocating traveling wave model of the piano hammer and the felt mallet. motions.This modelallows lips to operateon both the lower and higher ScottA. Van Duyneand Julius O. Smith, IIl (CCRMA, StanfordUniv., frequencysides of theair-column resonance frequencies. Oscillations gen- 660 LomitaDr., Stanford,CA 94305) erated by the total sound produetlonsystem are on both the lower and higherfrequency sides in the first and secondresonance modes, while in Recentwork has led to travelingwave stringand membranemodels the higher modesthey are realized only on the lower side. The harmonic using the digital waveguideand the 2-D digital waveguidemesh. This seriesselected from theseoscillations in the secondand higher modesto paperintroduces a new developmentfor thesemusical instrument models achievethe optimum pitch turns out to comprisean oscillationon the whichextends their usefulness: a traveling wave model for thepiano ham- Mgher side of the secondresonance frequency and oscillationson the mer, or felt mallet. When a mallet strikesan ideal membraneor string,it lower sides of the Mgher resonancefrequencies. This result closely sinksdown into it, feelinga pureresistive impedance. In the membrane matchesthe transitionof lip vibrationstates from the outward-striking case,the depressioninduces a circulartraveling wave outward.ff the vibrationat the secondmode (i.e., the lowestmode among the onesused membraneis bounded,reflected waves return to the strikepoint to throw musically)to the vocal-cord-likevibration at the highermodes, which is the malletaway from the membrane.This complexmallet-membrane observedin the simultaneousmeasurement IS. Yoshikawa,submitted to J. interactioncan havevery differentand difficultto predictacoustical ef- Acoust.Soc. Am.] of mouthpiecepressure and lip vibration. fects,particularly when a secondor thirdstrike occurs wMle themembrane 3300 d. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128thMeeting: Acoustical Society of Amerie• • Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp is still in motion,as in a drumroll. The pianohammer, or felt mallet,is Beistegui2103-C-203, Colonia Vertiz Narvarte, Delegaci6n Benito Jufirez, viewedas a nonlinearmass/spring (inductor/capacitor) system, the nonlin- M6xico 03020 D.E, Mexico) earspring representing the felt portion.By decomposingthe system into appropriatetraveling waves, a unitof delayis extracted in thediscrete time This paperdescribes in a succinctform an historicaltemperaments version,greatly simplifying the implementation. This wave digital hammer analysissystem designed for musicianswith advancedknowledge of in- can be attachedto any waveguidestring or membranemodel at a time- varyinglossless scattering junction. tervalictheory. By introducingthe concept of positivetrajectory reduction in thefifth circle diagram of thetemperament to be analyzed,it is possible to do a very fast calculationof the size of any intervalinside that tem- 9:20 perament,within an errorof -1 cent.The correspondingexact frequency ratio becomesobvious in many casesand it is easy to summarizeall the 4aMUa5. Rhythmogram analysis of human and synthetic intervalleinformation in one analysissheet. In additionto the fifth circle performance. Neil P. McAngusTodd (Dept. of Psychol.,Univ. of diagram,this sheetincludes frequency ratios for the chromatic,diatonic, Manchester,Manchester M13 9PL, United Kingdom), Eric Clarke,and Luke Windsor (Univ. of Sheffield,Sheffield S10 2TN, UK) andhexatonic scales (especially their size in cents),intervals with respect to the tonic,and the deviationin centsof eachnote from equaltempera- Previously,a methodof performanceanalysis has been described ment.With this system,piano tuningstudents can make comparisonsof whichis basedon a multitimescaledecomposition of the acousticsignal differenttemperaments, classify them, and understandtheir practicability [Todd,"Wavelet analysis of rhythm,"J. Acoust.Soc. Am. 93, 2290(A) for differenttypes of keyboardmusic. Besides, the practicaltuning instruc- (1993)].This analysis is sensitiveto a varietyof expressivedevices em- tionsfor eachtemperament can be comprehendedmuch better. Also, with ployedby musicalperformers including tempo, dynamics, and articulation. The outputof the analysisis a "rhythmogram"which resemblesthe time- this analysissystem, composers and keyboardisisare able to programany spanreduction of the theoryof Lerdahland Jackendoff.In this paper,the temperamentin an electronicsynthesizer with user-tuningoption, and the resultsof someanalyses of real and syntheticperformances are presented systemis even helpfulfor creatingnew temperaments. [Todd,"The dynamicsof dynamics:a modelof musicalexpression," J. Acoust.Soc. Am. 91, 3540-3550 (1992)]. 10:05 9:35 4aMUaS. Musicians' tendency to stretch larger-than-octavemelodic intervals. AndrzejRakowski (MusicAcoust. Lab., Chopin Academy of 4aMUa6. The pitch of elementsof a harmonic complex. Blane Andersonand W. Dixon Ward (Dept. of Commun.Disoral., Univ. of Music, Okolnik 2, Warsaw00-368, Poland) Minnesota,Minneapolis, MN 55455) Four musiciansexperienced in identifyingmusical intervals, but not It is well establishedthat the pitch of a sinusoldis shiftedaway from possessingabsolute pitch, tuned a pure-toneoscillator in individualses- the frequencyof a simultaneousnoise band or sinusold.Attempts to de- sionsto obtainvarious melodic intervals with a standardpure tone 500 Hz. termine whetheror not suchpitch shifts occur amongelements of a har- moniccomplex tone have given resultsthat are apparentlyconflicting. In Within a singletask the standardand variabletones were interchanging anendeavor to shedlight, or at leasta few shadows,on thequestion, seven until the intended value of a melodic musical interval was obtained. listenersadjusted a sinusoldto matchthe pitch of either the 3rd or 7th Stimuli were presentedvia earphonesat a loudnesslevel 50 phons.An harmonicof a preceding220-Hz 8-harmoniccomplex in which the har- isosonicfilter was usedto maintainequal loudness of tones.The variable monicin questionwas periodically interrupted. Both monotic and dichotic oscillatorwas set at eithervery low or very highfrequency at the begin- procedures,with correctionsfor diplacusis,were employedin order to ning of eachtask. The rangeof 3 octavesabove and 2 octavesbelow controlfor possibleadaptation effects. On average,the pitch of the 7th standardwas investigatedand each subjecttuned each of the 60 musical harmonicwas shifted upward by about25 centsdue to the presenceof its intervalswithin thisrange 10 times.The sequenceof tuningswithin each neighbors,but the pitchof the 3rd harmonicwas unaffected.In bothcases, octavewas quasirandom.The resultsare presentedas meandeviations of however, consistent individual differences were found, so that no un- eachinterval from its equallytempered value. The dispersionof resultsas equivocalconclusions can be reached. well as intersubjectand intrasubjectvariability is shown.A tendencyap- pearstoward stretching large melodic intervals; they are stretched the more 9:50 thelarger they are. Maximum stretch across 5 octavesinvestigated is about 4aMUa7. Historical temperaments analysis system. Alejandro S. 1 semitone.[Work supported by the PolishNational Committee for Sci- Esbri (Dept.of Electron.Music, Superior School of Music,Concepci6n entificResearch.] 3301 J. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128th Meeting:Acoustical Society of America 3301 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp THURSDAY MORNING, 1 DECEMBER 1994 CONCHO ROOM, 10:30A.M. TO 12:05 P.M. Session 4aMUb Musical Acoustics:Computer Music Uwe J. Hansen, Chair PhysicsDepartment, Indiana State University,Terre Haute, Indiana 47809 Chair's Introduction--10:30 Invited Papers 10:35 4aMUbl. Technicaland aestheticconsideratinns in interactivecomputer music systems. Todd Winklet (Dept.of Music,Brown Univ., Box 1924, Providence,RI 02912) The proliferationof reliableinteractive computer music systems has created opportunities for performersto directlyinfluence computermusic processes. Performing musicians are highlyvalued for their uniquesense of musicalexpression and taste:the everchanging subtleties of tempo,dynamics, timbre, and arficulation encompassed in the larger musical framework of musicalgesture andphrasing. How canmusicians communicate their highly refined skills to a computer,and elicit similarly musical results? This paper describestechniques whereby performers influence highly flexiblecompositional algorithms that are subtlyresponsive to musical nuances.These algorithms create MIDI dataused to controlsynthesizers and signal processors. Musical examples will be demonstrated usingFollowPlay, a computerprogram for interactivemusic and a real-timeenvironment for musiccomposition. The programconsists of a largecollection of softwaremodules o•ganized into threefunctional types: Listener Objects analyze and recordaspects of a musician'sperformance, Composition Objects respond by generatingMIDI data,and InterpreterObjects unify the entirecollection with a graphicaluser interface that handlestiming and intermodularcommunications. 11:05 4aMUb2. A touch sensitivedance floor/MIDI controller. RussellF. Pinkston (Dept. of Music, Univ. of Texasat Austin,Austin, TX 78712) A prototypeMIDI DanceSurface has been developed which is capableof transmittingprecise position coordinates, velocity, and pressureinformation in the form of standardMIDI messages.The surfaceconsists of a largenumber of forcesensing resistors (FSRs) whichare attachedto heavyduty plasticsheeting and covered with polyethylenefoam. The sheetsmay eitherbe placedon top of or beneatha standardMarley Dance floor. The FSRsare typically arranged in a gridwith 16 columns(left to right}and 4 rows(front to back),which results in a 16 ft. squaredance surface with 64 1X4 fl. velocityand pressure sensitive regions, each of whichis assigned a separaleinput channel of a Voltageto MIDI InterfaceBox which has 64 analoginputs, plus MIDI Out.The MIDI Box incorporates a MotorolaMC68HC11 microprocessor and can be programmedto convertinput/output analog signals to/from any desiredMIDI messages,on multipleMIDI channels.Hence, used in conjunctionwith an "intelligent"external MIDI processingsystem, it is ideal for usein interactivedance compositions in whichone or moredancers can affectboth the musicand lightingby the natureof their movementsand by theirprecise position(s) on the surface. Contributed Papers 11:35 algorithmsare made to enable the effective simulationof the late rever- berationresponses of concerthalls with arbitrarygeometries. For real-time 4aMUb3. Real-time computer simulation of concert hall acoustics: implementationof the extendedalgorithms, MasPar MP1 massivelypar- Arbitrary geometries. Turker Kuyel, Elmer L Hixson (.Dept.of Elec. allel computeris used. Eng., Univ. of Texas at Austin, Austin, TX 78712), and Russell Pinkston (Univ. of Texasat Austin,Austin, TX 78712) 11:50 Artificial reverberationis a challengingapplication of the computer 4aMUb4. Effectsof processingaudio signalsthrough equivalent technologyin the field• of musicalaeougtieg, archlteeture, multimedia, or color matching filters. Andrew Blackford (Elec. Eng., Univ. of evenin homeaudio. Real-time operation and high percepttonalquality are Oklahoma,Norman, OK 73019) and B. Espinoza-Varas(Univ. of the two challengesfor artificial reverberatordesign. In this paper, the OklahomaHealth Sci. Ctr., OklahomaCity, OK 73190) theoryand the implementationof "real-timecomputer simulation of con- cert hall acoustics"is discussed.Efficient real-fimealgorilhms based on In applicationsthat combine musical soundswith visual colors, it is theoreticalmodels have been built. The memory and compulalionalre- relevantto definerules that may relatecolor dimensions to the pitch and quiremeritsof thesealgorithms have been determined.Successful imple- timbreof sounds.In a firstattempt toward defining such ruies, this inves- mentationof thesetheoretical models and softwarealgorithms have been tigationexamined effects of processingaudio signals through equivalent implementedin UT ComputerMusic Studiosusing "Aceelerando" audio colormatching filters. Using Bulterworth bandpass filters, a threefilter processor."Accelerando" implementation assumes arbitrary room geom- bank(fl, f2, f3) wasdesigned to approximatethe response of filtersused etries for the early reverberationresponse, and rectangularroom geom- in the CIE 1931 StandardObserver [G. Wyszeckiand W. $. Stile,Color etries for the late reverberationresponse. Extensions of the model and Science(1982)]. The bandwidths of thecolor-matching filters were trans- 3302 J. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3302 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp posedto theaudible frequency range (0.02-20.0 kHz); the filter passbands usedto specifythe X andY coordinatesof CIE chromaticitydiagrams as were0.05-0.6 kHz and9.0-11.0 kHz for fl, 1.0-4.0 kHz for f2, and follows: X=Pfl/(Pfl+Pf2+Pf3); Y=Pf2/(Pfl+Pf2+P[3). 9.0-11.0 kHz forf3; thepassband gains were 1.15, 0.35, 1.0, and 1.75, Chromaticitydiagrams were obtained for: (a) 0.07-8.0 kHz sinusoids;(b) respectively.Synthesized audio signal were passed through the filter bank vowelswith different fundamentals; and (c) complexsounds consisting of andthe power, P, at thefilter outputs was computed. The P valueswere 2-21equal-energy sinusoids. [Work supported by OCAST] THURSDAY MORNING, 1 DECEMBER 1994 SAN MARCOS ROOM, 10:30 A.M. TO 12:00 NOON Session 4aNS Noise:Progress Report and Discussionon the ContinuingActivity on ASA's Role in Noiseand its Control Robert M. Hoover, Chair Hoover and Keith, Inc., 11381Meadowglen, Suite I, Houston,Texas 77082 Invited Paper 10:30 4aNSI. Noise: Progressreport and discussionon the continuingactivity on ASA's role in noiseand its control. RobertM. Hoover,Chair (Hooverand Keith, Inc., 11381Meadowglen, Houston, TX 77082) A discussionmeeting is beingsponsored by the TechnicalCommittee on Noiseto reviewprogress made to dateon the actions initiatedby the TechnicalCommittee on Noiseat the Denver1993 meetingto increasethe role of theASA in noiseand its control. Membersof the steeringcommittee will eachreview the specificactivities undertaken in the areasof education,collaboration with othersocieties, increasing public awareness of noiseand the establishmentof a taskforce to determinefeasibility of establishingan ASA clearinghouseon noise. THURSDAY MORNING, 1 DECEMBER 1994 WEDGWOOD ROOM, 8:25 TO 11:45 A.M. Session 4aPAa PhysicalAcoustics and Structural Acousticsand Vibration: Ray Methods in Radiation and Scatteringfrom Elastic Objects I Philip L. Marston,Cochair Departmentof Physics,Washington State University,Pullman, Washington99164-2814 Allan D. Pierce, Cochair Departmentof Aerospaceand MechanicalEngineering, Boston University, 110 CummingtonStreet, Boston, Massachusetts 02215 Chair's IntroductionS:25 Invited Papers 8:30 4aPAal.Waves and rays on fluid-immersedshells: Beyond spheres, cylinders, Donnell, and Watson. Allan D. Pierce(Boston Univ.,Dept. of Aerospaceand Mech. Eng., 110 Cummington St., Boston, MA 02215) Wavespropagating along ray paths on shellshave various descriptors, such as the dispersion relation that connects frequency and the,two prlneipalwavc-numbc;r components for eachpoint on the aurfac•.Other d•scriptorsin•lud• polarizationrelations: complex ratiosof amplitudesof quantitiesthat oscillate under the influenceof a propagatingwave. Such oscillating quantities include the componentsof the displacementvector for pointson the middlesurface, the acousticpressure at the externalsurface, and the 1ocally-spatially-averagedpassive forces exerted on the shell by the internalstructure. Energy balance relations are also wave descriptors.Such descriptors are derivabledirectly from the equationsof elasticityand fluid mechanics.In any frequencyand 3303 J. Acoust. Soc. Am., Vol. 96, No. 5, Pt. 2, November 1994 128th Meeting:Acoustical Society of America 3303 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp wave-numberregime (associated with theranges of scalesfor the intendedapplication) there are a limitednumber of possiblewaves types,but analogieswith waveson fiat platesare often not appropriate.The use of wave-basedtheory depends on whetherthe wavelengthalong the directionof propagationis somewhatsmaller than the effectiveshell radiusassociated with that direction.It is not necessaryfor the frequencyto be high and/orfor the wavelengthto be smallerthan both of the principalradii of curvature. Radiationof soundinto the fluid from waves traveling slower than the speed of soundis possibleas long as there is somepoint above the surfaceat whichthe extrapolatedphase velocity is supersonic;the explanationis analogousto why propellerswith subsonictip speedsradiate sound. [Work supported by ONR.] 9:00 4aPAa2.Backscattering enhancements and the impulseresponse of shells:Observations and ray theory. Philip L. Marston, GregKaduchak (Dept. of Phys.,Washington State Univ., Pullman, WA 99164-2814),and DavidH. Hughes(Naval Res. Lab., Washington,DC 20375-5350) Observationsof backscatteringby thin sphericalshells in waterwere carried out usingtone bursts and a novelbroadband transient source[G. Kaduchak,Ph.D. dissertation, WSU (1994)].Ray theory pertaining to someof theunderlying features observed will be discussedincluding: (a) a bipolarspecular feature of theimpulse response sensitive to theshell's mass-per-area; (b)a high-frequency enhancementof the toneburst response due to a backwardswave [G. Kaduchaket al., J. Acoust.Soc. Am. (in press)];(c) the coincidencefrequency enhancement of the tone burst and impulse responses associated with the a 0_ wave;(d) low-frequencyfeatures evidentin theimpulse response associated with the effect of curvatureon the a 0_ wave(or what some authors describe as the "Junget wave");and (e) periodicso wavepackets giving resonance dips up to moderatefrequencies. Feature (b) is sometimescalled the thicknessquasiresonance and for thestainless steel shell studied the ray theory uses the s 2 leakyLamb wave properties in thenegative group-velocityregion. The developmentof ray theoryfor situationswhere conventional thin shell theory is not applicablewill be reviewed.[Work supported by ONR.] 9:30 4aPAa3. Selectedtopics in computationalray methods. Roger H. Hackman (LockheedPolo Alto Res. Lab., Palo Alto, CA 94304-1191)and GaryS. Sammelmann(Coastal Systems Station, Panama City, FL 32407-5000) Severalselected topics intimately involved with the application of raytheory to acousticscattering are discussed. The first topic is theapplication of quantitativeray theory to thelow-frequency acoustic scattering from large aspect ratio solids. In thisapproach, thescattering amplitude is developedas a time-orderedperturbation series. The series for theelastic response is explicitly summed to obtaina closedform expression that is analogousto resultsobtained for sphericaland infinite cylindrical geometries through applicationof theSommerfeld-Watson transformation. Emphasis isplaced on novel features that have no counterpart on thesesimpler geometries(e.g., "bipolar" coupling phenomena) and their implications for resonanceexcitation. A secondtopic deals with a near-field/far-fieldtarget strength model for morecomplicated geometrical shapes that is underdevelopment at CSS. But theoretical andexperimental results are presented. A third topic is thehigh-frequency "quasi-resonance" phenomenon of thin shelled structures. Thestructure of the"quasiresonance" mode is obtainedfor bothcomplex wave number (real frequency) and complex frequency (real wavenumber) extensions of the reflection coefficient for a fluidloaded fiat plate. The results are used to synthesizethe scattering amplitudefor sphericalshells using forms previously derived for the Sommerfeld-Watsontransform. 10:00-10:15 Break 10:15 4aPAa4.Implementation of a ray tracingalgorithm to calculatethe acousticscattering from flnid loaded,doubly curved shells.Douglas A. Rebinsky,Andrew N. Norris (Dept.of Mech.and Aerosp. Eng., Rutgers Univ., P.O. Box 909, Piscataway, NJ 08855-0909),and YangYang (SFA,Inc., Landover,MD 20785) Raytracing is usedto calculatethe acoustical and structural response of smooth,elastic shells of nonseparableshape. The frequencyrange of interestis belowflexural coincidence but still high enough that asymptotic methods are applicable. The structure anddevelopment of ray-like solutions on arbitrarilydoubly curved shells is reviewedwith a discussionof two mechanisms: (1) a "background"response determined by thelocal inertial impedance, and (2) phasematching to longitudinaland shear waves. The backgroundresponse can be approximated by specular reflection, but the membrane waves require global treatment over the whole structure.After first calculating the coupling curves, which are the closed loci defined by phase matching with the incident wavefield, "pressure"rays are then sent out over the shell with each ray and its amplitude evolving according toa rayequation and a transport equation.Illustrative examples of raypaths and ray-tube areas will be presented for ellipsoidal and quasicylindrical shells. The use of theGaussian beam summation method to describethe wavefields will bediscussed. Numerical comparisons aremade with the exact resultsfor thecanonical geometries, and extensions to nonseparableshapes and discontinuous shells will be shownand discussed. [Work supportedby ONR.] 10:45 4aPAaS.Rays, modes, and spectra: Footprints in phasespace. Leopold B. Felsen(Dept. of Aerosp. and Mech. Eng., Boston Univ., 110 CummingtonSt., Boston,MA 02215) Raymethods have been used extensively to describe mid- and high-frequency, aswell as pulsed, phenomena associated with acousticpropagation in the presence of submerged solid or layered elastic structures. Therelevant wavefields include externally reflectedand diffracted, aswell as externally-internally coupled, progressing constituents, repetitive multiples ofwhich combine into oscillatorv(modal) forms. Full exploitation ofray methods forradiation and scattering scenarios, either forward (for classification) or inverse(for identification), isaided by systematic footprinting of the (space-time)-(wave number-frequency) characteristics of the 3304 J.Acoust. Soc. Am., Vol. 96, No. 5, Pt.2, November1994 128thMeeting: Acoustical Society ofAmerica 3304 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp variouswave objects in a (configuration)-(spectrum)phasespace catalog. "Clean" footprints obtained from forward asymptotics for certaintest problems are shown to be diffused(a) by windowedprocessings that are applied to extractthese footprints from data (imaging),and (b) by space-time limits imposed on the data set. Examples include submerged elastic cylindrical, and finite fiat plate, geometries.Also included are simple models of truncatedstrict or perturbedperiodicity, with illustrationof superresolutionand backpropagation[L. Carin et al., J.Acoust. Soc. Am. (submitted)].[Work supported by ONRand AFOSR.] 11:15 4aPAa6.Postmodern quantum mechanics:Chaos and the Schœfidlngerwave equation. StevenTomsovic (Dept. of Phys., WashingtonState Univ., Pullman,WA 99164-2814) Recenttheoretical and experimentaldevelopments are drivinga growinginterest in the asymptoticwave behaviorof quantum mechanics.The underlyingray theoryis basedon the trajectoriesfound in the correspondingclassical mechanical system. Many systemsexhibit some chaotic motion and present a numberof challengesfor the theory.Recent advances will be illustratedwith the stadiumbilliard which has become one of thepremiere paradigms of highlychaotic dynamics [E. J. Hellerand S. Tomsovic,Phys. Today46(7), 38 (1993)].Both the time-dependent and stationary solutions will be discussed.[Work supported by NSFGrant No. PHY-9305582.] THURSDAY MORNING, 1 DECEMBER 1994 PECOS ROOM, 9:00 TO 11:00 A.M. Session 4aPAb PhysicalAcoustics and Bioresponseto Vibration and to Ultrasound: Bioeffects of Ultrasound and Cavitation WesleyL. Nyborg,Chair PhysicsDepartment, University of Vermont,Burlington, Vermont 05405 ContributedPapers 9:00 A commonnoninvasive test for fetal well-beinginvolves transmitting an audio-frequencyacoustic signal into the amniotic fluid by meansof a 4aPAbL Bioeffectsof positiveand negativepressure pulses in vlvo. mechanicalvibrator, which is appliedto themother's abdomen close to the MichaelR. Bailey,David T. Blackstock(Appl. Res. Labs. and Mech. fetal head.This testhas been simulated in the laboratory,using a silicone Eng.Dept., Univ. of Texasat Austin,Austin, TX 78713-8029),Diane robbermodel uterus of sphericalshape filled with water. The outside of the Dalecid, Carol H. Raeman,Sally Z. Child, and Edwin L. Carstensen modelwas excitedby an impedancehead and a load-distributingcontact (Univ. of Rochester,Rochester, NY 14627) disk.Mechanical impedance measurements were comparedwith similar Murine lung andDrosophila larvae were usedto compareeffects of measurementson volunteersubjects at about30 weeks' pregnancy,and isolatedpositive and negative pulses on tissuecontaining gas bodies. The showedsimilar trends as a functionof frequency.The modelwas then used basicpulse, produced by an underwaterspark, was positive. It couldbe to establisha transferfunction between the excitingforce and the acoustic isolatedby floatingabsorptive, nonreflecting rubber on the water surface to pressurein thewater-filled cavity. A simpletheoretical model is presented preventreflection. When an isolated negative pulse was desired, the rubber which accountsfor the main featuresobserved experimentally. Results was removedand the direct,positive pulse was blockedby insertinga ifidicatethat commercial fetal stimulators can produce intrauterine sound jagged-edgebarrier between the spark and the exposure area. The jagged pressuresashigh as 30 Parms (180 Pa peak pressure) close to thepoint of edgerendered the diffracted wave (from the barrier edge) incoherent and excitation.The actuallevel depends on the thicknessof the subcutaneous thereforenegligible in theexposure area. Exposure levels were varied by fat layerwhich couples the vibratorto the uterus. alteringthe proximityof the exposurearea to the source.For eachlevel, lungdamage and larva mortality due to 20-pulseexposures were mea- 9:30 sured.Positive pulses were foundto be at leastas damaging,to both tissues,as negativepulses having the same amplitude. If thedamage was 4aPAb3. Propagationof elasticwaves inside concretionsto simulate due to cavitation,this resultis contraryto conventionalwisdom, which dynamicfailure of kidneystones and gallstonesduring lithotripsy. holdsnegative pressure largely responsible for the violenceof inertial Girish Dahakeand S. M. Gracewski (Dept. of Mech. Eng., Univ. of cavitation.It is speculatedthat the expansionand ensuing catastrophic Rochester,Rochester, NY 14627) collapseof a bubbleare hindered in thepresence of tissue. [Work sup- Reflectionand superposition of stresswaves is analyzedusing finite portedby ONR, NIH, andARL: UT IR&Dprogram.] differencetechniques to betterunderstand the effectof stoneparameters andgeometry on the distribution of strainswithin kidney stones and gall- 9:15 atoncaduring lithotripay. Concrotiona of irregularg•ometri½s are subjected to ultrasonicwave sources that simulate lithotripter pulses. The time evo- 4aPAb2. Sound transmission to the human fetus. ChristopherL. lution of strainis calculatedinside cylinders of rectangularand circular Morfeyand Roger J. Pinnington(Inst. of Soundand Vib. Res., Univ. of crosssections, due to an incidentradially diverging source in the liquid Southampton,Southampton SO17 1BJ, United Kingdom) surroundingthe solid.Two schemesare consideredto explicitlyaccount 3305 d. Acoust.Soc. Am., Vol. 96, No.5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3305 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp for theliquid-solid interface conditions. Both schemes account for varying Previously,cavitation due to pulsedmegabertz-frequency ultrasound gridsizes and give identical results for straightinterfaces, but thesecond wasdetected using a techniquethat only lookedfor theonset of detectable schemealso handles irregular interfaces. The time sequenceobtained nu- cavitafion[CMabrese et al., Advancesin NonlinearAcoustics, edited by H. mericailyfor strainat the centerof a rectangularcylinder also matches Hoba•k,pp. 394-399 0993)]. This methodprovides little information wellwith theexperimental results IS. M. Gracewskiet eL, J. Acoust.See. aboutcavitation production rates, which may be bettercornrated to a Am. 94, 652-661 (1993)].In addition,strain contours are plotted for the mechanicalbioeffect than the thresholdalone. A modifiedapproach using propagationof P (longitudinal)and SV (shearvertical) waves inside a a passivecavitation detector [Roy eta!., J. Acoust.Soc. Am. 87, 2451- circularcylinder. It is shownthat the reflectionfrom the concaveback 2458 0990)] is usedto determinethe rate of cavitationas a functionof surfaceof the circularcylinder has a focusingeffect with the subsequent acousticpressure amplitude. Measurements are repeatedfor a varietyof formationof focal zones(caustics). pulselengths (from 3 to 1130/as)and duty cycles (from 0.1% to 20%)and at frequenciesof 1, 2.25,and 5 MHz. Initial resultssuggest that the thresh- 9:45 old pressurefor cavitationis weaklydependent on pulselength and de- creaseswith increasing duty cycle. [Work supported by NIH throughGrant 4aPAb4. The propagation of ultrasonic waves through a bubbly No. RO1 CA39374.] liquid into tissue:A linear analysis. QuanQi, JohnG. Harris (Theor. Appl.Mech. UIUC, 216Talbot Lab., 104 S. WrightSt., Urbana, IL61801), 10:30 and WilliamD. O'Brien (Elec.Cornput. Eng., UIUC, Urbana,1L61801) 4aPAb7, Focused acoustic pulses of finite amplitude and their The steady-stateresponse induced by an ultrasonicwave in a structure influence on cavitation bubble dynamics. M.A. Averkiou, L. A. comprisedof two layers,a bubblyliquid, and a viscoelasticsolid with a Crum (Appl. Phys.Lab., Univ.of Washington,Seattle, WA 98105},and rigidboundary, is studiedin thelinear approximation. This structure mod- M. F. Hamilton (Univ. of Texasat Austin,Austin, TX 78712-1063) els a steadilycavitating liquid in contactwith tissue.The uppersurface of theliquid is drivenharmonically and models the source.The lowersurface A computercode that solves the KZK equationin thetime domain [Lee of the solidis rigid and modelsbone. Though the cavitationprocesses are andHamilton, Ultrasonics lntL 91 ConferenceProceedings (Butterworth- nonlinear,the propagationis approximatedas linear.The modelof the Heinemann,Oxford, 1991), pp. 177-180] is modifiedto include the effects bubblyliquid is a simplecontinuum one, supplemented by allowingfor a of focusingon pulsedsound beams of finiteamplitude. Single cycle pulses, distributionof differentbubble radii andfor dampingof the oscillationsof similar to thoseused in lithotripsyand high intensityfocused ultrasound eachbubble. The modelcontains three functions, the probabilitydistribu- (HIFU) surgery,are considered.The numericalresults demonstrate the tiondescribing the distribution of bubbleradii, and two funclionsmodeling combinedeffects of nonlinearity,absorption, diffraction, and focusingon the mechanicalresponse of, respectively,the individualbubble and the the waveformdistortion and shockformation in shortacoustic pulses. tissue.Numerical examples are workedout by adaptingdata takenfrom Self-defocusingassociated with shockformation is alsotaken into account. variouspublished sources to deducethe parametersof thesefunctions. Propagationcurves are shownfor the positivepeak pressureamplitude Theseexamples permit an assessmentof the overallattenuation of the (P+) andthe negative peak pressure amplitude (P_) alongthe axis of the structure,and of themagnitude of thepressure and particle velocity in the source.The calculatedpressure waveforms are usedas inputto computer bubblyliquid, and of the tractionand the particledisplacement in the codesthat modelbubble dynamics. Predicted radius-time curves are pre- tissue.[Partial support from Arjo, Inc., Morton Grove, IL.] sentedfor theresponse of a bubbledue to a focusedacoustic pulse of finite amplitude.Gas diffusionfrom the liquid into the vaporbubble, and the 10:00 rolesof P+ and P_ in the diffusionprocess, are alsoconsidered. [Work supportedby the NationalInstitute of Health.] 4aPAbS. Cavitation in water generated by pulse Doppler ultrasound, Ronald A. Roy (Appl. Phys. Lab., Univ. of Washington,Seattle, WA 10:45 98105) and J. Brian Fowlkes (Univ. of MichiganMedical Ctr., Ann Arbor, MI 48109) 4aPAb8. The biological relevance of transient cavitation measurementsperformed in water: The effect of shear viscosity. A recentlypublished study reports the directobservation of transient JohnAllen (Dept. of Mech. Eng., Univ. of Washington,Seattle, WA microcavitationin water produced by clinicaldiagnostic ultrasound [Hol- 98105)and RonaldA. Roy (Univ.of Washington,Seattle, WA 98105) landet aL, IEEE UFFC 39, 95-101 (1992)].Results are presented from a similarstudy in whichan aqueoussuspension of 0.2-/•m-diampolystyrene Recentyears have seen a hostof directexperimental evidence of tran- sphereswas insonatedby an ATL UM9 scanneroperating in the pulse sientmicrocavitation in water producedby shortpulses of megahertz- Dopplermode at 3.5 and 5.0 MHz. The suspensionwas degassedto ap- frequencyultrasound [Roy et al., J. Acoust.Sec. Am. 87, 2451-2458 proximately90% of saturation.Using a computerautomated active cavi- (1990);and others]. However, to ourknowledge there have been no pub- tationdetector [Roy eta!., J. Acoust.Sec. Am. 87, 2451-2458(1990)], lishedaccounts of directobservations of suchmicrocavJtaflon activity in cavitationproduction rates were obtained for a varietyof pulseparameters biologicalmedia. It is usefulto relatethe resultsof the aqueousexperi- suchas intensity,peak negative pressure, pulse length, and pulse repetition mentsto the likelihoodof producingcavilalien in tissue.To do this, one frequency.Results suggest a cavitationthreshold which is fairly well pre- mustassess the relevantdifferences between the two media.As a firststep dictedby the mechanicalindex calculated from the variouspulse wave- in thisprocess, a numericalimplementation of the Gilmoreequation for formsobtained/n situ. [Work supported by NIH throughGrant No. RO1 adiabaticbubble pulsations is employed[Church, J. Acoust.Sec. Am. 83, CA39374.] 2210-2217(1988)] and compare predicted thresholds in waterand in biologicalmedia modeled as a viscousfluid. Comparisons are made with 10:15 the analyticaltheory of Hollandand Apfel [IEEE UFFC 36, 204-208 (1080)].The requirementthat, at the thresholdpressure, the bubblecol- 4aPAb6. Cavilalien from short pulses high-frequency ultrasound: A lapsetemperature exceed 5000 K providesthe rigorouscomparison crite- study of cavitation product'on rates and their dependence on rion. Resultsare viewedin light of recentexperimental results obtained in acoustical parameters. Adam Calabrese (Dept. of Phys., Univ. of water[Calabrese et eL, J.Acoust. Sec. Am. 95, 2856 (1994)]and in tissue- Mississippi,Oxford, MS 38677) and Ronald A. Roy (Univ. of mimickingphantom materials [Zbeng eta!., J. Acoust.See. Am. 95, 2855 Washington,Seattle, WA 98105) (1994)].[Work supported by NIH throughGrant No. RO1 CA39374.] 3306 d. Acoust.Soc. Am., Vol. 96, No.5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3306 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp THURSDAY MORNING, 1 DECEMBER 1994 TRINITY A AND B, 8:00 TO 10:10 A.M. Session 4aSPa SpeechCommunication: Production and Perceptionof Speechby ChildrenI Peter Assmann, Cochair Schoolof HumanDevelopment, University of Texasat Dallas, Box 830688,Richardson, Texas 75083 William Katz, Cochair Callier Centerfor CommunicationDisorders, 1966 InwoodRoad, Dallas, Texas75235-7298 Chair's Introduction---8:00 Invited Papers 8:05 4aSPal.Artatomic development of the vocaltract: Implicationsfor speechmotor control and acousticproperties of speech. RayD. Kent (Dept.of Commun.Disord., Univ. of Wisconsin,1975 Willow Dr., Madison,WI 53706) It hasbeen proposed that models of speechproduction should be developedwith consideration of age and gender differences. Althoughsome important age differences in anatomyand acoustic patterns of vocalizationhave been described between infants and adults,much less attention has been given to the anatomicdevelopment of the speech production system between infancy and adulthood.This talk reviews the anatomic development of the craniofacial, oral, and laryngeal systems of speechproduction between birthand young adulthood. Implications ofthe developmental patterns are considered for the ontogeny of speechproduction, especially speechmotor control and acoustic patterns of speech.Consideration also is givento genderand race as theyrelate to vocaltract anatomyand its development in children. Topics to be reviewedinclude: craniofacial skeleton, nasopharynx, tongue, lips, and larynx. Theoverall pattern of developmentwill be summarizedfor eachsystem and intervals of especiallyrapid growth will be identified.A majorhypothesis to be evaluatedis whethergrowth is harmoniousacross the majoranatomic systems. 8:30 4aSPa2.Development of skilled speechproduction in children. ShariR. Baum (Schoolof Commun.Sci. & Disoral.,McGill Univ., 1266 PineAve. W., Montreal,PQ H3G 1A8, Canada)and William F. Katz (Univ. of Texasat Dallas, Dallas,TX) Therehas been much recent interest in themanner in whichchildren develop mature speech production capabilities. Investigations of bothnormal speech acquisition and developmental speech production impairments have contributed to ourcurrent knowledge base. A consistentfinding is that youngchildren's speech is highlyvariable, both in its temporaland spectralattributes, and that this variabilitydiminishes gradually with age.However, the exactmanner in whicharticulatory precision emerges (or fails to emergein speechdisorders) continues to be the subjectof debate.For example,some research on anticipatorycoarticulation suggests a developmentalprogression from syllable-to segment-basedtiming strategies while other research suggests the opposite.Similarly, somestudies of compensatoryarticulation show comparable degrees of motorequivalence in youngchildren and adults, while others showthat this aspect of motorcontrol emerges gradually with maturation.This presentationwill reviewkey experiments(primarily basedon acousticanalyses), consider potential explanations for the controversialdata, and discuss methodological alternatives that mayassist in theresolution of outstandingquestions. Recent evidence indicates that specific motor patterns of differentarticulalors will play a majorrole. 8:55 4aSPa3.The developmentalrole of acousticboundaries in speechperception. RalphN. Ohde (Div. of Hear.and SpeechSci., Box 552, Station 17, Vanderbilt Univ. School of Medicine, Nashville, TN 37232-8700) During production,there are frequentabrupt changes in the amplitudeor in the spectrumof the sound,and thesevariations are regardedas boundariesbetween speech sounds. The informationappears rich in cuesfor phoneticfeatures of the segmentsoccurring within 10 to 30 ms of the acousticboundaries. Recent research examining children's speech shows that the informationcontained within the acousticboundaries of their productionsprovides important cues for consonantplace of articulation.In addition,inters- peakervariability for thesesegments is low, ascompared to propertiessuch as formanttransitions. Current studies also reveal that for bothadult and child speech a principalmechanism involved in processingacoustic boundary cues involves short-term memory, and that the elimination of Doundary information negatively affects perception of place of articulation, particularly for children's speech. Furthermore,the importanceof acousticboundaries in children'sspeech extends to their perceptionof placeof articulationof both consonantsand vowels. Young children accurately process place of articulationfrom very shortduration stimuli, which includes the periodof rapidspectrum change. In the currentpaper, this evidencesupporting the salleneeof acousticboundary information in children'sspeech and children's perception of speechwill be presented.[Work supported by NIH, DC00464.] 3307 J. Acoust. Soc. Am., Vol. 96, No. 5, Pt. 2, November 1994 128th Meeting:Acoustical Society of America 3307 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 9:20 4aSPa4.The developmentof speechperception: Beyond infancy. AmandaC. Walley,Victoria L. Michela (Dept.of Psychol., Univ.of Alabamaat Birmingham,Birmingham, AL 35294),and JamesE. Flcgc (Univ.of Alabamaat Birmingham,Birmingham, AL 35294) In comparisonto whatis knownabout speech perception in infancyand adulthood, much less is knownabout perception in childhood.Nevertheless, there is a growingconsensus that phonetic/phonemic segments are not present in the"initial state," but only emergegradually over the course of childhoodas units of speechrepresentation and/or processing. How perception may become more segmentallybased by virtueof vocabularygrowth will beconsidered--as the mental lexicon grows in overallsize, as individual lexical itemsbecome more familiar, and as particular regions of thelexicon become more "crowded" (i.e., as the acoustic-phonetic similarity amongdifferent words increases). The research to be presentedincludes recent data beating on children's perception of nativeand non-nativevowels in word and nonwordcontexts. Age-related changes in spokenword representationand processing may have importantconsequences for otherdevelopmental achievements, such as thegrowth of metaphonologicalknowledge/skills and early readingability, as well as for successin learninga secondlanguage. More generally, the purpose is to helpset an agendafor future researchthat will providea morecomplete picture of thedevelopmental trend for speechperception. [Work supported by NIH.] 9:45-10:10 PANEL DISCUSSION THURSDAY MORNING, 1 DECEMBER 1994 SAN SABA ROOM, 10:15 A.M. TO 12:15 P.M. Session 4aSPb SpeechCommunication: Production and Perceptionof Speechby ChildrenII (PosterSession) Peter Assmann, Cochair Schoolof HumanDevelopment, University of Texasat Dallas, Box830688, Richardson, Texas 75083 William Katz, Cochair Callier Centerfor CommunicationDisorders, 1966 InwoodRoad, Dallas, Texas75235-7298 ContributedPapers All posterswill beon display from 8:00 a.m. to 12:15p.m. To allow contributors anopportunity to see other posters, contributors of odd-numberedpapers will beat their posters from 10:15 a.m. to 11:15a.m., and contributors of even-numbered papers will be at their postersfrom 11:15 a.m. to 12:15p.m. Posters will remainon display until 10:00 p.m. on Friday. 4aSPbl. Prosodicfeatures of foreignertalk registerin the speechof M. Komell,William F. Katz (Dept.of Commun.Disord., Univ. of Texas 10- to 11- and 6- to 7-year-oldAmerican children. JenniferSullivan at Dallas, Callier Center,1966 Inwood Rd., Dallas, TX 75235), and andAndrea G. Levitt (WellesleyCollege, 106 Central Street, Wellesley, CherylBeach (3408 CusterSt., Cincinnati,OH 45208) MA 02181-8289) At whatage and in whatways do children begin to modifytheir speech Althoughrecent evidence suggests that young children use prosodic in the presenceof a non-nativespeaker? Two groupsof six American informationto "bootstrap"themselves into syntactic comprehension, little childreneach, three girls and three boys, were asked to teachtwo children, is knownabout how children use prosody to signalsyntactic boundaries in onea nativespeaker of Englishand another with limitedEnglish profi- their spokenutterances. A speechelicitation task examined the extentto ciency,to recitethe pledgeof allegianceand two children'spoems. The whichchildren and adults control duration and intonation to markphrase childrenin theolder group were between 10 and11 years old, and those in boundariesin spontaneous speech. Adults and young children (ages 5 and theyounger group were between 6 and7. Whenspeaking to thenon-native 7) wereasked to describegroupings of coloredblocks in a mannersuch child,the older group of childrenproduced shorter utterances, repeated that a blindfoldedlistener could tell "whichblocks go together."This often,and spoke significantly more slowly than when speaking to the procedureelicited utterances corresponding to three syntactic bracketings nativespeaker. Repetitions were generally spoken with a lowerF0, andthe of thephrase "pink and green and white." Acoustic analysis of subjects' olderchildren also used a significantlyreduced F0 rangewhen addressing productionsindicated that adults reliably controlled duration (i.e., syllable thenon-native speaker. There were no differencesin theprosodic adjust- lengthening,pauses) and intonationfall-rise patterns to signalphrase mentsmade by theboys and the girls. The children in theyounger group generallymade few modificationsin theirspeech to the non-nativechild, boundaries.In contrast,children's productions were highly variable and althoughsome of theolder subjects in thisgroup occasionally modified showedno evidence of intonationcues being involved. Individual subject theirspeech to thenon-native speaker in wayssimilar to thoseof theolder analysessuggested that some of the7-year-old children used duration cue children.[Work supported by NIH GrantNo. 1 R15HD28173-01.] to signalphrase boundaries, although the contrasts were not as marked as in theadult data. The results were interpreted asshowing that by age 7, 4aSPb2.Prosodic cues for phrasalboundaries in productionsby mostchildren have not yet mastered prosodic cues for phrasal boundaries childrenand adults. SushamaVerma, Anne M. Mannering,Branden in theirspeech production. 3308 J.Acoust. Soc. Am., Vol. 96, No. 5, Pt.2, November1994 128thMeeting: Acoustical Society ofAmerica 3308 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 4aSPb3.A preliminaryinvestigation of how prosodiccues may help is synchronizedwith the auditorypresentation of anothersyllable. Previ- young infants' to extract words from natural sentences. Francisco ousaudiovisual speech studies have shown that adult perception is strongly Lacerda,Ulla Sundberg,and ChristinAndersson (Inst. of Linguist., influencedby the visualspeech information whereas the perceptionof StockholmUniversity, S-10691 Stockholm, Sweden) youngchildren (5-8 years)shows a veryweak influence of visualspeech patternsand a strongbias favoring the auditory speech information. In this Thispaper presents preliminary results of a studyassessing 6-month- investigation46 childrenin fourage groups (5, 7, 9, and11 yearolds) and old infants'capacity to pick up linguisticallyrelevant information pre- 15 adultswere presented with conflictingaudiovisual syllables in whichan sentedin complexnaturalistic linguistic contexts. The head-turnprocedure auditory/ba/sequencewas combined with visual/va/,/0a/,/ds/, and/ga/ wasused to investigatethe infants' ability to discriminatetarget words that sequences,respectively. The resultsindicated that the influence of auditory areembedded in naturalcarrier sentences. The sentenceswere producedas informationdecreased with increasingage, while the influenceof visual infant-directedor adult-directedspeech ("direction") and for eachdirec- informationand the integrationof auditory and visual informationin- tionof thetarget word occurred either in emphaticor nonemphaticposition creasedacross the age groups.In addition,an adult-likeresponse pattern ("focus").A largenumber of sentences,including all thepossible combi- wasobserved in only half of the childrenin the oldestchild subject group nationsof directionand focus, was first submitted to adultscrutiny in order (10-12 yearsold) suggestingthat the ability to utilizevisual speech infor- to selectunambiguous carrier sentences in which adequatetarget words mationcontinues to developbeyond the ageof 12. [Worksupported by weresubsequently edited. Both adults and infants were tested by thehead- NSERC.] turn procedure,to assessthe differencesbetween the infants'and adults' useof the prosodicinformation. [Research supported by The Bankof 4aSPb7. Infant dependence on acoustic cue redundancy: SwedenTercentenary Foundation, Grant No. 94-0435.] Discriminationof the word-finalvoicing contrast. MargretA. Orme and Linda Polka (Schoolof Commun.Sci. and Disoral.,McGill Univ., 4aSPb4. The nature of top-down representationsthat affect 1266Pine Ave. West,Montr6al, PQ H3G 1A8, Canada) bottom-upphonetalc processing in children and adults. Angela L. Bauman (Dept. of Psychol.,SUNY-Buffalo, Park Hall, Box 604110, Discriminationof a word-finalstop consonant voicing contrast,/bid/- Buffalo,NY 14260-4110)and JudithC. Goodman (Univ. of California /bit/, by adultsand infantsat two ages(6-8 and 10-12 months)was at SanDiego, La Jolla,CA 92093) investigatedin a category-changeconditioned headturn procedure across threestimulus conditions: full cue (FC), burstand closurecues neutralized Adultsand childrenuse lexical knowledge to interpretphonemes in speech[W. F. Ganong,JEP: HPP 6, 110-125(1980); Hurlbun and Good- (BCCN),and vowel duration neutralized (VDN). Adults performed at ceil- man,in preparation;S. Nittrouerand A. Boothroyal,J. Acoust.Soc. Am. ing levelsfor all threeconditions. No infantage differences were observed. 87, 2705-2715(1990)]. This study examines the nature of lexicalrepre- However,there was someevidence that infantsbenefitted from the pres- sentationsnecessary for top-downeffects. In a baselineassessment, 5-year- enceof redundantacoustic cues (FC>BCCN, but FC>VDN). Infantsper- olds and adultsheard stimuli from seven-stepvoice onsettime (VOT) formedsignificantly better with the VDN stimuliindicating that final re- lease burst information is more salient to infants than vowel duration continua.The continua endpoints formed nonwords (e.g., beb--,p..•.). Sub- jectswere then trained on oneendpoint from each continuum in oneof two differencesfor this/bid/-/bit/contrast.This resultdiffers from findingsof learningconditions. Subjects in the exposurecondition heard items in a prior researchon adult and infant perceptionof suchcontrasts which carrierphase five times(e.g., "The soundyou will hearis •."). Subjects showeda prominentuse of the precedingvowel durationcue. This finding suggeststhat vowel durationbecomes useful as a cue to final stopvoicing in the conceptcondition heard five instancesof eachitem usedas a picture with linguisticsophistication. [Work supported by NSERC.] label,in definitionalsentences, and in a sentenceidentifying its superor- dinatecategory. After training,subjects again heardthe baselineVOT 4aSPb8. Sensitivityto the distinctivefeatures of vowelsin newborn continua.Children's and adults'phoneme boundaries shifted such that a speechsegmentation. Kelley L. Kaye (Univ.of Texasat Dallas,School greaterpropoRion of tokenswere perceived as compatible with thetrained of Human Develop. GR41, P.O. Box 830688, Richardson,TX endof the continuumregardless of learningcondition. This suggeststhat 75083-0688) minimalexposure to a soundpattern, rather than fully-specifiedlexical knowledge,can resultin top-downeffects in speechperception. A previousstudy investigating the unit of speechperception in new- horns[K. L. Kaye,J. Acoust. Soc. Am. 92, 2299(A)(1992)] yielded results 4aSPbS. Voice pitch as an aid to speechreadingin young children. suggestingthat speech processing in newbornsrequires both the definition JoannaD. Fagg (Schoolof Commun.Sci. and Disoral.,McGill Univ., of the multidimensionalperceptual space of the utterancesin termsof 1266 PineAve. West,Montreal, PQ H3G 1A8, Canada) smallperceptual units, and the chunkingof phenoemesinto syllablesfor The speechreadingability of a groupof youngchildren with normal cognitiveprocessing in memory.The presentstudy focused on the percep- hearingwas assessedusing a simple,closed-set, single word identification tual process,investigating whether newborns are sensitiveto the distinc- task.The speechreadingtest was devisedsuch that the accurateidentifi- tive featuresof vowels.A vowel can be characterizedby threeopposed cationof half of the testitems would be expectedto be facilitatedby the distinctivefeatures. Using an operant ([SI) sucking procedure, one group of abilityto perceivevoicing contrasts. All of thesubjects performed the task newbornsreceived, over earphones,a presentationset with 0 distinctive twice, once with visual speechinformation only and once with visual featurevariation, a secondgroup with greaterthan 0 but lessthaa I dis- informationsupplemented by a voicepitch signal, derived using an elec- tinctivefeature variation, and a third groupwith 2 distinctivefeatures trolaryngograph.Subjects were foundto be ableto identifyfamiliar words variationbetween the computersynthesized vowels in the set. Results throughspeechreading, both in the silent conditionand with the addition indicatedthat respondingis affectedby the numberof distinctivefeatures voicepitch signal. No significantoverall improvement was foundto result requiredto definethe vowelset, and together these studies indicate that from the provisionof voice pitch information.However, subjects were newbornscan segmentspeech in termsof syllables,phoneroes, and dis- foundto significantlyimprove in their ability to identify thosetest items tinctivefeatures. Distinctive features are normallydefined in articulatory whichrequired the discriminationof voicingcontrasts. Conclusions were terms,yet newbornsdo not havethe appropriatearticulatory equipment. drawnabout the normal speech perceptual processes of youngchildren and The theoreticalimplications of thiswill be discussed. aboutthe possible benefits of providingsimple speech pattern information, 4aSPb9. Prototype preference and magnet effects in newborns: suchas thevoice pitch signal, for childrenwith profoundhearing losses. Evidencefor an innatecomponent. Michelle Aidridge (CallicrCtr. for 4aSPb6. A developmentalstudy of audiovisualspeech perception Commun.Disord.-UTD, 1966 lnwoodRd., Dallas,TX 75235) using the McGurk paradigm. Nell S. HockIcy and Linda Polka (Schoolof Commun.Sci. andDisord., McGill Univ., 1266 Pine^vc. West, Withinthe vowel space there are subareas which correspond to specific Montr6al,PQ H3G 1AS, Canada) vowel categories.Within each subareathere is a point which definesthe bestexemplar or prototypeof thatvowel. Kuhl [J. Phon.21, 125-139 The developmentof audiovisualspeech perception was examinedin (1993)] hasargued that the areaimmediately surrounding a prototypeis thisexperiment using the McGurkparadigm (McGurk and MacDonald, perceptuallyshrunken, with reducedvariance in respondingto pointsin 1976), in which a visualrecording of a personsaying a particularsyllable thatimmediately surrounding area, a magneteffect [Kuhl (1993)]. Erapiti- 3309 J. Acoust. Soc. Am., Vol. 96, No. 5, Pt. 2, November 1994 128th Meeting: Acoustical Society of America 3309 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp cally, prototypepoints correspond to the averagesof large numbersof that parentallanguage directed to 1ow-SESchildren differs from that di- utterances.This leadsto the hypothesisthat prototypes are learned.It is rectedto mid-SESchildren in kind and amount,such that 1ow-SESchil- equallypossible that prototypesare innate[Kuhl (1993)]. To decidebe- drenmay be thoughtof as enduringdeficits in linguisticexperience. Re- tween thesetwo hypothesesan experimentwas run with newborns.The sultsshowed that 1ow-SESchildren performed differently from mid-SES vowel /y/was usedin the experiment;/y/does not occurin Texas.The childrenon bothexperimental tasks, displaying results similar to thoseof newborns'only experiencewas providedin the experiment."Best exem- younger,mid-SES children in otherstudies. These results suggest that plar" wasequated with "mostattractive" measured by listeningtime in an linguisticexperience plays a rolein thedevelopment both of matureper- operantchoice task. Resultsindicated that experiencedid not determine ceptualweighting schemes for speechsignals and of phonemicawareness. preference.The prototype/y/waspreferred, regardless of the experience provided.No significantmagnet effect occurred. A second,slightly differ- 4aSPbll. Maturational limitationsto pronunciationaccuracy in a ent, experimentdid find a magneteffect. The differencebetween the two secondlanguage. Grace H. Yeni-Komshian(Dept. of Hear.and Speech experimentsmay explainwhy the magneteffect occurs. Sci.,Univ. of Maryland,College Park, MD 20742)and JamesE. Flege (Univ.of Alabama,Birmingham, AL 35233) 4aSPb10.Deficits in linguisticexperience delay the developmentof mature speech perception abilities and of phonemic awareness. This studyexamines pronunciation proficiency in a secondlanguage SusanNittroucr (BoysTown Natl. Res. Hospital,555 North 30th St., (L2) asa functionof theage of (L2) acquisition.Accuracy of pronuncia- Omaha, NE 68131) tionof wordsand sentences produced by Korean-Englishbilinguals who beganlearning their L2 (English)between 2 and24 yearsof ageis re- Onemodel of howmature patterns of speechperception develop sug- ported.All subjectswere born in Koreaand had residedin the U.S. for at geststhat the weighting of variouskinds of acousticinformation changes least8 years.Their average age at thetime of testingwas about 24 years. as a resultof experiencewith a nativelanguage. It hasfurther been sug- Theresults are based on thesubjects' accuracy of pronunciationof vowels gestedthat this developmental shift in perceptualweighting is relatedto andconsonants in Englishwords and sentences. Preliminary findings, re- the developmentof maturesensitivity to the phoncmicstructure of one's gardingsegmental phonemes, indicate no majordifficulties up to about11 nativelanguage (i.e., phonemic awareness). Thus it couldbe predictedthat yearsfor L2 acquisition.Those who learnedEnglish (L2) at or laterthan deficitsin linguisticexperience would delay both the developmentof ma- 12 had significantlylower pronunciationaccuracy scores. These difficul- ture patternsof speechperception and of phonemicawareness. This pre- tieswere more evident in vowelsthan in consonants.The resultssupport liminary study testedthis predictionby administeringlabeling and the criticalperiod for languagelearning hypothesis. The discussionwill phonemic-awarenesstasks to two groupsof children:those of mid socio- addressthe problemof specifyingthe optimumconditions for secondlan- economicstatus (SES) and thoseof low SES. Severalstudies have shown guageacquisition and first languageretention. THURSDAY MORNING, 1 DECEMBER 1994 BALLROOM B, 8:00 A.M. TO 12:15 P.M. Session 4aUW UnderwaterAcoustics: Signal ProcessingII Gary R. Wilson, Chair AppliedResearch Laboratories, University of Texas,P.O. Box 8029,Austin, Texas 78713-8029 ContributedPapers 8:00 8:15 4aUWl. Towed vertically directive source for shallow-water 4aUW2. Performanceof adaptive beamforming (ABF) for fixed scatteringmeasurements. Tommy G. Goldsberry (Office of Naval receiverbistatic active systems. YungP. Lee and JohnHanna (Sci. Res.,800 N. QuincySt., Arlington,VA 22217-5660), JosephM. Monti, ApplicationsInt. Corp., 1710 GoodridgeDr., MS T1-3-5, McLean,VA and MichaelWerbicki (Naval UnderseaWarfare Ctr., NewportDiv./ 22102) DetachmentNew London, New London, CT 06320-5594) A uniquetool for low/mid-frequency(LF/MF) shallow-waterrever- Datacollected from a seatest have been processed and analyzed to berationand scattering measurements has been developed. The towed ver- examinethe performance of adaptive spatial beamforming techniques in ticallydirective source (TVDS) is designedto overcomethe two critical fixedreceiver bistatic active systems. Adaptive beamforming using both deficienciesin mostattempts to measureLF scatteringcharacteristics of theleast-mean-squared (LMS) method and block sample-matrix-inversion the ocean bottom in shallow water--insufficient source level and inad- (SMI)method have been studied. The LMS method uses the current input equatedireetivity of the aoundsource. Although TVDS provideshigh algnalto recuralvelyupdate the adaptive weight; it convergesslowly and sourcelevel and directivityat LF and MF (220 to 230 dB over the fre- providesonly a littleadaptive gain (over the conventional beamforming) quencyband from 400 to 4000 Hz) it is designedfor use on 3000 ton for reverberationsuppression. On the otherhand, the SM! methoduses an researchvessels at towdepths to 180m. An articulatedstrut allows aper- estimateofthe current covariance matrix to recursively update the adaptive turefor a 20 degvertical beamwidth at 600 Hz but permitsTVDS to be deployedand retrievedwith the low-frequencyarray retracted.An MF weight;it convergesrapidly and provides more than 10 dB adaptivegain. arraywith centerfrequency of 3000 Hz is mountedin the verticalstabilizer It is wellknown that adaptive processing isvery sensitive to mismatchdue of TVDS and also providesa 20 deg verticalbeamwidth. Provision for to systemerrors or environmentalfluctuations. To recoverthe signal lost in simultaneoustransrfiission atLF andMF will permitfrequency diversity in mismatch,two robust SMI adaptivebeamformers, Feedback-Loop White- measurementsover a decadeof frequencywith scatteredsignal reception Noise-Constrained(FLWNC) method and Signal-Coherence-Constrained on theTVDS transducerarrays or an adjuncttowed array. TVDS design Reduced-Rank(SCCRR) method, were applied. They successfully recover andtest results will be discussed.[Work sponsored by ONR.] signalsand maintain excellent clutter suppression. 3310 d.Acoust. Soc. Am., Vol. 96, No. 5, Pt.2, November1994 128thMeeting: Acoustical Society ofAmerica 3310 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 8:30 9:15 4aUW3. An assessmentof the variability of low-frequencyactive 4aUW6. Improvementof ultrasonicsynthetic aperture imaging via sonar performancein shallowwater, JeroenFranken, Ching-Sang deconvolutionpreprocessing. Nobuyuki Ishikawa, Yoshio Fuiii Chiu, JamesH. Miller (Code EC/Mr, Naval PostgraduateSchool, (Control & AI Lab., JapanAtomic Energy Res. Inst., Tokai-mura, Monterey,CA 93943), and WarrenW. Denner (EOS Res. Assoc., Naka-gun,Ibaraki, 319-11 Japan),and YoshikuniShinohara (Nuclear Monterey,CA 93940) PowerEng. Cooperation,Toranomon, Minato-ku, Tokyo, 105 Japan) Ultrasonicsynthetic aperture imaging is a usefultechnique for detect- The performanceof a genericlow-frequency, active sonar was simu- ing cracksin the materialand viewing the underwaterenvironment. Since lated usinga broadband,coupled mode, propagationmodel. The low- high-frequencyultrasonics are utilizedfor suchpurposes, transducers with frequencyactive system consisted of a 1000-Hzsource with source level of sufficienttransient response have been made available. On the otherhand, 220 dB and a towedhorizontal array of hydrophones.The oceanenviron- ordinarytransducers for measurementsin air are of the resonanttype mentused in thesimulation was 159 tomographic snapshots of theBarents becauseof comparativelylow practicalfrequency used. However, the uti- Sea PolarFront, taken every 5 min. Thesetomographic images over a lizationof resonanttype transducers for syntheticaperture imaging in air rangeof 35 km providea virtualocean in whichsystem performance and makesthe measurementresolution poor. This degradationcomes from the environmentaldata requirementscan be assessed.The probabilityof de- narrow-bandcharacteristics of transducers,which cause signal distortion in tectioncalculated as a functionof time for 13 h is comparedwith that transduction.In this study,to compensatefor the narrow-bandcharacter- estimatedusing a range-and time-independentassumption. The impor- isticsof transducers,a deconvolutiontechnique is appliedfor preprocess- tanceof coastalacoustic tomography for tacticalapplications will be dis- ing of syntheticaperture imaging and improvementis attainedthereby in cussed. the caseof usingthe resonanttype transducer.The filter usedfor decon- volutionis of the FIR type which is designedin the time domain.The desiredfilter output has bandpass characteristics with a centerfrequency of 8:45 40 kHz correspondingto the resonantfrequency of the transducerand the passbandis 6 kHz. Experimentalresults show that resolutionof synthetic 4aUW4. Reverberation characterization and suppressionin the apertureimaging is improvedby a factorof 3.0 in the rangedirection and presenceof channel spreading. Geoffrey S. Edelson (Lockheed 3.5 in the lateraldirection by usingdeconvolution processing. Sanders,Inc., MAN6-2000, P.O. Box 868, Nashua,NH 03061-0868) and Ivars E Kitsteins (SACLANT UnderseaResearch Centre, La Spezia, Italy) 9:30 4aUW7. Optimum detection of solid spherical elastic objects of In activesonar, the reverberation plus target time seriescan be modeled uncertain composition in an uncertain reverberation-limited as the joint convolutionof the signalwith the channeland scattererim- environment. M. Wazenski, V. Premus, D. Alexandrou, and L. W. pulseresponses. Especially in shallowwater, the channelresponse cannot Nolte (Dept. of Elec. Eng., Duke Univ., Box 90291, Durham, NC be adequatelymodeled as propagationover discretepaths. A maximum 27708-0291) likelihoodtype approachis proposedfor estimatingthe arrival timesof signalswhich have propagated via a continuumof paths,i.e., temporally Detectionof solid sphericalelastic objects is approachedvia optimal spreadchannels. The channelspreading is includedin the modelby using detectionand estimationtheory in conjunctionwith acousticscattering a discreteprolate spheroidal sequence (DPSS) to representthe channel modelsfor both the object and the environment.The objectiveis the impulseresponse of given duration,but unknownshape. Thus the un- developmentof full field(amplitude and phase) optimal decision methods for high-frequencyactive detection of a targetin the vicinity of the seal- knownparameters are the arrivaltimes and the scalefactors of the DPSS loon This parametricapproach incorporates the inherent uncertaintyof expansion.The parametersare estimatedusing an iterativemethodology both objectcomposition and seafloorgeomorphology. The acousticmodel which decomposesthe original data into its constituentcomponents and usedfor the sphericalobject is the well-known modal seriessolution and then estimatesthe parametersof the individual componentsthrough a is parametrizedby objectsize, density (object and medium), compressional sequenceof one-dimensionalsearches. Experimental data and computer wavespeed (object and medium), and shear wave speed. This deterministic simulationexamples indicate that the methodperforms well. model is used to predict the target signaturemeasured at an array of sensors.Acoustic modeling of the seaflooris performedby applyingthe 3-D Helmholtz-Kirchoff formulationto the anisotropic,power-law de- 9:00 scriptionof seafloorrelief due to Goff and Jordanand is parametrizedby correlationlength (two directions),linearion direction, rms height,and 4aUW5. Dynamic stereo imaging of hard-skinned sonar targets. fractaldimension. This modelis usedto predictthe spatialand temporal Terry L. Henderson(Appl. Res.Lab., Univ. of Texasat Austin,Austin, coherenceof the scatteredsound field. Illustrativedetection examples are TX 78713-8029) presentedalong with receiveroperator characteristic (ROC) performance. [Worksupported by ONR: OceanAcoustics.] The visible portionof a hard-skinnedsonar target can be scannedin xyz coordinatesby beamforminga planararray, to give a 3-D representa- tion.However, a simpleline arrayrunning along the x axiscan providea 9:45 projectionview of a targetthat lies along the z axis, with its upperand 4aUW8. A generalized framework for high-frequency optimum lowersurfaces being projected semitransparently onto the xz plane,giving target detection in a shallow water, random wave scattering a pictureanalogous to that of a biologicalspecimen viewed with a slide environment.V. Premus,D. Alexandrou,and L. W. Nolte (Dept.of microscope.If theline arrayis tumbledabout the z axis,it will appearthat Elec. Eng.,Duke Univ., Durham,NC 27708-0291) the target is revolvinga7ound the z axis. When this tumblingview is presented14 ø out of phaseto the left and righteyes, a stereoscopicview of It has been shown that for the case of Gaussian reverberation, the the tumblingtarget is obtained,with its 3-D form revealedby the brain's likelihoodratio detector can be maderobust with respectto inexactknowl- innate tomographicsignal processingcapability. In-water experiments edge of the acousticscattering medium by incorporatinga probabilistic have beenconducted for severaltarget shapes. Other meansof generating descriptionof environmentaluncertainty and a modelfor the wave-number dynamic displayshave been developedthat are suitable for scanningob- spectrumof lhc bottom-interactingacouslic 1icld [Premus at al., J. Acoust. jects on the seafloor.A videotapeof resultsfor severaltargets has been Soc.Am. (submitted)].In thiswork a generalizedform of the optimum prepared.Further simplifications of the array structureand processingare detectoris presentedwhich requires full-field (amplitudeand phase)mod- possible,with some limitationsand weaknesses.[Work supportedby elingcapability for the scatteredfield and relies on MonteCarlo integration ARL:UT IR&D.] to treat environmentaluncertainty. The performanceof the generalized 3311 d. Acoust. Soc. Am., Vol. 96, No. 5, Pt. 2, November 1994 128th Meeting:Acoustical Society of America 3311 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp detectorformulation is comparedto that of the originaldetector formula- samplesbased on this statisticalcharacterization. The labeledclasses are tion, which is a specialcase based on explicit modelingof the reverbera- characterizedby a histogramassociated with a multiresolutiondecompo- tion second-order statistics that is exact for the case of Gaussian rever- sitionof the data in eachclass. Classification of a new sampleis then beration.Tradeoffsqnvolving the prior knowledge,modeling assumptions performedby calculating,for eachlabeled class, the conditionalprobabil- andcomputational requirements are discussed. [Work supported by ONR, ity of the samplegiven the statisticsof thatclass. These conditional prob- OceanAcoustics.] abilities,which are interpretedas relativelikelihoods that the samplebe- longsto eachof theclasses, are calculated in a recursirecomputation that 10:00 proceedsfrom coarseto fine resolution.A simple, efficient computer 4aUW9. Equal-likelihoodprobability modelingin active and passive implementationusing associative arrays is presented.Successful classifi- sonar. RichardPitre (NavalRes. Lab., Washington, DC 20375-5350) cation of both time seriesand time-frequencydistributions of marine- mammalvocalizations is demonstratedusing relatively small numbersof The equal-likelihoodrationale JR, Pitreand N. R. Davis,J. Acoust. labeledsamples (•10 perclass). [Work supported by ONR.] Soc.Am. (to be published)]for the selectionof probabilitymodels has been extendedand strengthened.The methodis shownto be optimally 11:15 robust,testable, and correctable.Nonlinear parameter estimation and fil- teringequations are developedbased on this formalismand its application 4aUW13. Remoteidentification of moving acousticobjects. RogerF. to modelingactive sonar in a randomwaveguide is formulated.[Work Dwyer (NavalUndersea Warfare Ctr., New London,CT 06320) sponsoredby ONR.] Often in applicationsit is desiredto remotelyidentify an objectfrom its acousticsignature. In activesonar the objectis insonifiedby a trans- 10:15-10:30 Break mittedwaveform and the receivedpressure is processedto localizeand identify the object.Here, the receivedpressure time seriesfrom spherical 10:30 acousticobjects in motionthat havebeen insonified by linearfrequency modulated(LFM) waveformsare usedto identifythe objects.The un- 4aUW10. Reconstruction of a per/odic time-domain signal "buried" knownobject's unknown constant velocity using a uniqueproperty of the in Gaussiannoise. StefanT. Sidahmedand Antal A. Sarkady (Dept.of fourth-ordercumulant spectrum [J. Acoust.Soc. Am. 93, 1460-1465 Elec.Eng., U.S. NavalAcad., Annapolis, MD 21402) (1993)]is extractedand then its transferfunction is extracted.The results Powerspectral analysis does a reasonablygood job of signaldetection for five sphericalacoustic objects in motionare discussed.Three methods, but fares poorly in characterizationbecause the phaseinformation is ig- aleconvolution,matched filtering, and fourth-order cumulant spectrum de- noredin the spectralcomputations. From spectralanalysis, an initial or convolutionto extractthe object'stransfer function are compared. seedvalue for the periodof the targetsignal is obtained.The original digitallysampled noisy time signalis resampled(up/down sample rate 11:30 conversion)at sucha ratethat precisely an integernumber of timesamples areobtained on eachcycle of thequasiperiodic target signal. These noisy 4aUW14. Towed array geometry estimation during ship's cyclesare synchronouslyaveraged in the time domainand an estimatefor maneuvering. S. M. Jesus,P. Felisberto (UCEH-Univ. of Algarve, the shapeof the targetsignal is computed.The samplerate conversion, and PT-8000Faro, Portugal),and F. Coelho (HidrographicInst.-PT-1000 the synchronousaveraging is repeateduntil the rms value of the resultis Lisbon,Portugal) maximized(i.e., phasecancellation is minimized).The voltagesignal- Towedarrays of hydrophonesare commonlyused as receivingappa- noiseratio of the reconstructedtarget signal is proportionalto the square ratusfor determiningthe directionalityof the underwateracoustic field. It root of the numberof targetcycles averaged. This procedurewas tested is well knownthat a line arraybeam response has an inherentleft-right with laboratorytype signals and found to havean excellentperformance at ambiguityand that any deformation of the arraywill producea distortion signal-to-noisevoltage ratios as low as -40 dB. onthe estimated acoustic field directionality. In particular,the array cannot be operatedduring ship's maneuvering which is a potentialdrawback to its 10:45 operationalusage. In theory,if the arrayis not straightbut the hydro- phone'sposition are knownat eachtime instant,the beamformercould be 4aUWll. Asymptotic behavior of the matched-phasenoise filter in compensatedin order to obtaina correctedbeam response. More, depend- the limit of low signal-to-noiseratio. B. Edward McDonald and ing on the arrayshape, the left-right ambiguitycould also be resolved.In GregoryJ. Orris (NavalRes. Lab., Washington, DC 20375-5000) practice,it is extremelydifficult to obtainsufficiently accurate measure- It has beenshown elsewhere that informationabout the shapeof the mentsof the hydrophonepositions. This paperpresents the measurements noisespectrum with no phaseknowledge can be usedto constructa noise obtainedat sea,with a 156 m aperturearray, instrumented with several rejectionalgorithm which we call the matched-phasefilter. Here, it is highprecision tiltmeters, compasses, depth sensors, and accelerometers. demonstratedthat to first order in the signal-to-noiseratio (SNR), the After filteringand preliminaryanalysis of the sensorposition data it is matched-phasefilter is capableof improvingan arbitrarilylow SNR (•1) concludedthat the array is nevera straighthorizontal line. The arrayhas to orderunity when the spectrumof the noiseis knownexactly. This approximatelya catenary shape with vertical deviations at thetail up to 15 analysisaccounts for propertiesof numericalresults with computer- m at constanttow speed. Under maneuvering, thearray is largelyalefor- generatedsignal and noise,with SNR valuesbelow - 100 dB. Sincecom- mated and a consistentshape could be estimatedon real time from the putershave dynamic ranges far in excessof audioequipment, these results nonpositionsensors. The useof the estimatedgeometry for acousticdata in an actualexperiment would be limited by the dynamicranges of the processing,shows that consistentbeam responses(close to theoretical) equipmentused. Also shownare examples illustrating the performanceof couldbe obtained even under strong array distortion. It is alsoshown, with the algorithmwhen the noisespectrum is knownonly approximately. real data,that the knowledgeof arraygeometry significantly improves full-field matchingfor sourcelocalization and/or bottom characterization. 11:00 11:45 4aUW12. A multiresolution,likelihood-based approach to pattern classificationwith application to characterization and automated 4aUW15. A fundamentalstudy of multipath localizationusing recognitionof marine mammal sounds. ThomasJ. Hayward (Naval bottomed receivers in shallow water. Randall W. Smith, Jaime F. Res.Lab., Washington, DC 20375-5350) Nualart,and David E. Grant (Appl.Res. Lab., Univ.of Texasat Austin, P.O. Box 8029, Austin, 'IX 78713-8029) A multiresolution,likelihood-based statistical approach is presentedfor characterizinglabeled classes of samples(e.g., measuredtime seriesor The basiccharacteristics of multipathpropagation from a shallow time-frequencydistributions of acoustic transients) and for classifyingnew sourceto a bottomedreceiver in shallowwater are investigated,with an 3312 d. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3312 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp emphasison applicationto the problemof sourcelocalization. For this 12:00 fundamentalstudy, the environmentis assumedto be ideal (perfectlyre- 4aUW16.Time domainbased optimal a posteriorisource localization fieclingbottom and surface, range invariant depth, isovelocity). The delays in a shallow-waterenvironment. I.A. Shoreyand L. W. Nolte (Dept. be{weentravel times along different propagation paths depend on the lo- of Elec. Eng., Box 90291, Duke Univ., Durham,NC 27708-0291) cation{range, depth, and bearing) of the sourcerelative to the receiver. Measurementsof severalsuch time delayscan be usedto determinethe An optimala posterionprobability approach to matchedfield process- location of the source. II was found lhat the Iravel time difference between ing usingtime domaindata in the form of arrivaltimes is implemented. pathshaving differing numbers of tmversalsof thewater column depends The inherentrobustness of thistechnique is demonstratedwith respectto stronglyon rangebut weakly on depth.In contrast,the travel time differ- conveutionaluarrow-band frequency domain based matched field process- encebetween paths having an equalnumber of traversalsbut whichhave ingtechniques. A ray-tracing method and a widebandnormal mode method differentsource angles (i.e., up or down)depends strongly on depthbut arecompared as modelingmechanisms for thisapplication. Localization weaklyon range.As an example,these obse•ations are applied to localize performancefor a shallow-watersource localization problem is presented a towed soundsource in a real environment.The exampleprovides a usingprobabilities of correctlocalization. Specific results for thisshallow- backgroundfor an assessmentof how accuratelya real environmentmust waterenvironment are presentedas a functionof signal-to-noiseratio. be modeled in order to obtain reasonable results. [-Researchsponsored by ONR OceanAcoustics and NUWC.] THURSDAY MORNING, 1 DECEMBER 1994 NUECES ROOM, 8:30 A.M. Meeting of AccreditedStandards Committee S12 on Noise to be heldjointly with the U.S. TechnicalAdvisory Group for ISO/TC 43/SC1 Noiseand ISO/TC 94/SC12Hearing Protection D. L. Johnson,Chair S12 EG&G SpecialProjects, Albuquerque Operations, Albuquerque, New Mexico87119-9024 P.D. Schomer,Chair, U.S. Technical Advisory Group (TAG) for ISO/TC43/SC1, Noise (and Vice Chair S12) U.S. CERL, P.O. Box 4005, Champaign,Illinois 61820 H. E. yonGierke, Vice Chair,U.S. TechnicalAdvisory Group (TAG) for ISO/TC43/SC1, Noise 1325 MeadowLane, YellowSprings, Ohio 45387 E. H. Berger,Chair, U.S. TechnicalAdvisory Group (TAG) for ISO/TC 94/SC12,Hearing Protection CabotSafety Corporation, 7911 Zionsville Road, Indianapolis, Indiana 46268-1657 StandardsCommittee S12 on Noise.Working group chairs will reporton theirprogress for theproduction of noisestandards. The interactionwith ISO/TC 43/SC1 and ISO/TC 94/SC12 activitieswill alsobe discussed,with referenceto the internationalstandards underpreparation. The Chairs of therespective U.S. Technical Advisory Groups (H. E. vonGierke and E. H. Berger)will reporton currentactivities of theseInternational Technical Subcommittees under ISO andthe meeting of ISO/TC431SC1, held in London,U.K. in November 1994. Scopeof S12: Standards,specifications and terminology in the fieldof acousticalnoise pertaining to methodsof measurement, evaluationand control; including biological safety, tolerance and comfort and physical acoustics as relatedto environmentaland occupationalnoise. 3313 J. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3313 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp THURSDAY AFTERNOON, 1 DECEMBER 1994 NUECES ROOM, 1:30 P.M. Meeting of AccreditedStandards Committee SI on Acoustics to be held jointly with the U.S. Technical Advisory Group for ISO/TC 43 Acousticsand IEC/TC 29 Electroacoustics G. S. K. Wong, Chair S1 Institutefor National MeasurementStandards (INMS), National Research Council, Ottawa, Ontario KIA OR6, Canada R. L. McKinley,Vice Chair S1 U.S.Air ForceAAMRL/BBA Aerospace Medical Research Laboratory, Wright-Patterson AFB, Dayton,Ohio 45433 P. D. Schemer,Chair, U.S. TechnicalAdvisor (TA) for ISO/TC 43, Acoustics U.S. CERL, P.O. Box 4005, Champaign,Illinois 61820 H. E. von Gierke,Vice Chair,U.S. TechnicalAdvisory Group (TAG) for ISO/TC 43, Acoustics 1325 MeadowLane, YellowSprings, Ohio 45387 V. Nedzeinitsky,U.S. TechnicalAdvisor (TA) for IEC/TC 29, Electroacoustics NationalInstitute of Standardsand Technology(NIST), Building233, RoomA149, Gaithersburg,Maryland 20899 StandardsCommittee SI on Acoustics.Working group chairs will reporton theirpreparation of standardson methodsof measure- mentand testing,and terminology, in physicalacoustics, electroacoustics, sonics, ultrasonic• 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 intemational activities in [SOfFC 43 Acoustics, and IEC/TC 29 Electroacoustics,will also be discussed.The chairs of the respectiveU.S. Technical Advisory Groups for ISO/TC43 (H. E. yonGicrke), and IEC/TC 29 (V. Nedzelnitsky),will reporton current activitiesof theseTechnical Committees, including their most recent meetings. (ISO/TC 43 andIEC/TC 29 bothmet in London,U.K. duringNovember 1994). Scopeof SI: Standards,specifications, methods of measurementand test and terminology in thefield of physicalacoustics including architecturalacoustics, electroacoustics, sorties and ultrasorties, and underwater sound, but excludingthose aspects which pertain to biologicalsafety, tolerance and comfort. THURSDAY AFTERNOON, 1 DECEMBER 1994 SABINE ROOM, 1:30 TO 5:25 P.M. Session4pAB Animal Binacoustics:Animal BinacousticsResearch Methodology H Mardi C. Hastings,Chair Departmentof MechanicalEngineering, The Ohio State University,206 West18th Avenue,Columbus, Ohio 43210-1107 Chalr's Introductlon--l;30 Invited Papers 1:35 4pAB1. Oreacousticemissions in animals:An intricate view of the peripheralstage of acousticprocessing. Brenda L. Lensbury-Martin,Glen K. Martin,and Martin L. Whitehead(Univ. of Miami Ear Inst.(M805), P.O.Box 016960, Miami, FL 33101) Otoacousticemissions (OAEs) represent sounds generated by the ear that can be simply measured from the ear canal. In particular, OAEsprovide a meansto examinein detailthe encoding properties of theouter hair-cell system, which presumably generates emitted responses.Animal research using emissions as a responsemeasure consists of fourgeneral classes of utilizationincluding the use of 3314 J. Acoust.Soc. Am., Vol. 96, No.5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3314 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp OhEs:(1) to describethe basic limits of auditoryfunction for a particularspecies, (2) to monitoror indexcochlear function during experimentalmanipulations of the auditory system, (3) to enhanceunderstanding of the fundamental nature of thevarious emissions, and(4) to furtherknowledge about the physical basis of certainafflictions that affect human heating using animal models of specific pathologies.The purposeof thispresentation will be to providean overviewof OAEs includingtheir essential basis, to reviewthe equipmentand proceduresused to adequatelydetect this responsemeasure, and to presentexamples of the uniqueapplications of emissionmeasurements in animals.By reviewingthese many aspects of OAEs, the greatbenefits along with the limitationsinherent to thisattractive research technique can be appreciated.[Work supported by PHS (DC01668,ES03500).] 2:00 4pAB2.Application of Navy IUSS for whaleresearch. ChristopherW. Clarkand David K. Mefiinger (CornellLab. of Ornithol., Bioacoust.Res. Prog., 159 SapsuckerWoods Rd., Ithaca,NY 14850) The recentapplication of Navy IntegratedUndersea Surveillance System (IUSS) data(Whales '93) for detectingand tracking low-frequencysounds from whales has led to a renewedinterest in theuse of thesearrays for marinemammal research. Previous work with sparsearrays has limited the detection and tracking to rangesof tensof kilometers,while the IUSS allowsfor ordersof magnitude greatercoverage. SOSUS dataare processedvia computersystems specifically developed for detectingand trackingwhales, as well asthrough annotations, to determineindividual, geographic, and seasonal variability in vocalizationsfor at leastfour species (blue, finback,humpback, and minke),and thereare alsonumerous sounds from unidentifiedwhales. Given that theseanimals use these deliberatepatterns of intenselow-frequency sounds for either communication,navigation, or food finding,verification of sound functionwill be deducedthrough careful examinationof behavioralcontext and other environmentalconditions such as local productivity,bathymetry, and oceanography. Results from the Whales '93 andcontinuing Dual Use projects will be presented.This will includedescriptions of signalvariability for the differentspecies of marinemammals and preliminary interpretation of the resultsin termsof soundfunction. [Work supported by ONR andNRL.] 2:25 4pAB3.The role of passivesonar technology in marinemammal population assessment. William E. Evans (TexasInst. of Oceanogr.,Texas A&M Univ.,P.O. Box 1675,Galveston, TX 77553)and RobertBenson (TexasA&M Univ.,College Station, TX 77843-3367) When sonardetection of marineorganisms is mentionedmost every one visualizesactive sonars. This is becausedevelopment of passivesonar systems has been essentially limited to military use until recently.With the developmentof new designs,submarines could run deeperand more silent than in the past. The developmentof more sensitivelistening systems was essential.With the developmentof improvedpassive sonars, a vastvariety of biologicalnoise mostly generated by cetaceanswas documented.Most dolphinsand whales are eitherdirect or incidentalnoise makers. In manycases sound generating cetaceans can be identifiedas to familyand in somecases to species(e.g., Physeter macrocephalus, Tursiops truncatus). In 1992The Texas Institute of Oceanography, Centerfor Bioacoustics,Texas A&M University,in partnershipwith the National Marine Fisheries Service, Southeast Research Center, conducteda three-yearacoustic/visual seasonal census of the cetaceansof the Gulf of Mexico.A lineartowed array and sonobouy arrayswere used. Thirteen of the 21 speciesof cetaceansknown to occurin the Gulf of Mexicowere detected acoustically using the towedarray. Acoustic contacts were compared with thedistribution and density of thesespecies determined by thevisual survey. The useof a mobiledirectional acoustic array had the advantageof detectingthe presenceof cetaceans24 h a day.Because of thisthe numberof acousticcontacts was significantly greater than those for the visualsurvey. In the caseof the spermwhale it waspossible to assessthe distributionand also estimate the populationdensity. 2:50 4pAB4.Vocalization tracking of blueand fin whalesin the North Pacific. MarkA. McDonald,John A. Hildebrand,and Spahr C. Webb (ScrippsInst. of Oceanogr.,Univ. of California,La Jolla,CA 92093-0205) Arraysof seafloorseismometers provide the ability to trackvocalizing marine mammals in thedeep ocean over a radiusof 20 km or morewith positionaccuracy as goodas severalhundred meters. These tracking data can be usedto inferswimming speed and apparentrespiration rate, as measured by positionchange and by repeatedpauses in thevocalization sequence. Speed and respiration ratecan be comparedduring times of relativequiet, during the passageof largemerchant vessels, and during times of man-made acoustictransmissions to evaluate possible effects of low-frequencynoise. Seafloor seismometer arrays also allow study of fin whale call sequences,which often are interactionsbetween multiple whales located several kilometers apart. That thesefin whalesare interacting,rather than calling independently, is suggested by: (1) consistentspacing between calls with rarely overlapping calls, (2) a distinctivespectral signature for eachwhale, and (3) synchronizationof respirationamong vocalizing whales. 3:10 4pABS.Zooplankton population density assessment with acoustics. D.V. Holliday(Tracor Appl. Sci., Anal. and Appl. Res. Div., 9150Chesapeake Dr., SanDiego, CA 92123) Thereare a varietyof acousticalmethods which can be usedas tools in basicand applied research in biologicaloceanography, estuarineecology, and in limnology.The modeof applicationof thesetools is oftenas importantand interesting as are thesensor characteristics.Two suchsensor systems, the TAPS and the BITS, are beingused to senseand describetemporal and spatial distributionsof small zooplanl•ton•n situ. Thesesensors operate as activesonars at discrete,multiple l'requencies from hundre•lsof kilohertzto severalmegahertz. Acoustical design parameters and the modeof deploymentfor severalof thesesystems will be presented.TAPS operates in eithera profilingmode or in a castmode. BITS estimates zooplankton abundance at discrete depths from a mooringand telemeters the data to shore.Data from both will beused to illustratetheir application in both marine and estuarine ecosystemsscience. Illustrations ofthe acoustical data each of thesesystems produces will beillustrated, along with several ancillary 3315 d. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128th Meeting:Acoustical Society of America 3315 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp abioticmeasurements and derived estimates of thesize structure and biomass of theunderlying population of zooplanktonthat causes thescattering. [Work supported by ONROceanic Biology, NSF Biological Oceanography, andTracor.] 3:30-3:40 Break 3:40 4pAB6.Auditory-evoked potentials obtained using continuous amplitude-modulated tones. WilliamF. Dolphin (Dept.of Biotaed.Eng., BostonUniv., Boston,MA 02215) Auditory-evokedpotentials (AEPs) recorded from the scalp surface are neurogenic potentials arising from the massed discharge of neuralpopulations in response to acousticstimuli and provide a "window"on thephysiological basis of auditoryprocessing. AEPs, in particularthe transient-evokedauditory brain-stem response (ABR) havebeen widely used in humanclinical settings for the evaluationof auditoryfunctioning. Recently, several new techniques using continuous amplitude-modulated tonal stimuli have been investigated.Many of thesetechniques take advantage of auditorynonlinearities which result in theauditory system acting as an envelopeextractor. This envelope following response (EFR), phase locking of neuraldischarge to waveformperiodicities, has been measuringusing two-tone, sinusoidal amplitude-modulated, and multitone, multiple envelope components signals. The EFR offers greatpromise for frequencyspecific threshold measurements, especially for low-frequencyaudiomerry and for the examinationof auditoryprocessing of complexsounds. 4:00 4pAB7.A portablesystem for physiologicalassessment of hearing in marineanimals. D.A. Carderand S. H. Ridgway(Biosci. Div., NavalCommand, Control and Ocean Surveillance Ctr., RDTE Div., Code511, 49620Beluga Rd., Rm. 200, SanDiego, CA 92152) A compactfield portable system has been developed and tested for presentingsound stimuli (20 Hz-200 kHz) andacquiring and analyzingsound and microvolt-level electrophysiological responses in marineanimals. Stimulus sound is controlledfor frequency, amplitude,duration, rise/fall times, interstimulus interval, phase, and masking noise. Analysis is by synchronousaveraging, with artifactrejection, and is displayed,stored, and may be printed,if desired.The weather resistant system includes hardware based on a 486with fast bus and software for presenting shaped tones and pulses, acquiring up to eightchannels of datafor display,storage, and analysis.The system includes all necessaryfunctional units (suction cup electrodes, high gain (X500K) amplifiers, analog-to-digital anddigital-to-analog converters, fiber-optic intermodule connection, computer with LCD screenthat can be seen in brightsunlight, an internal1.2-gigabyte hard disk, power amplifier, transducers, power source) and is constructedin a setof smallcases that can bc hand carriedto remotesites. To date,the system has been used for hearingtests in dolphins,Tursiops, white whales, Delphinapterus, and a beachedpygmy Sperm whale, Kogia. [Work supported by ONR.] 4:20 4pAB8.Dynamics of dolphinbiosonar search and detection.J.E. Sigurdson(Code 511, NCCOSC, RDT&E Div., 53405Front St., SanDiego, CA 92152-6530) Thebiosonar emissions of a free-swimmingdolphin were measured with respect to directionand timing while the animal searched forand reported objects at variousranges and bearings from a testenclosure. The technology allows a quantitativedescription of the pulse-by-pulsescan pattern of thefreely moving animal and subsequent inferences about search strategies, echo-integration time, functionalbeam coverage, and learning effects on biosonar performance. Presently, the methods are being extended to testan animal froma boatin theopen ocean with measurement of the animal's attitude and movement in three dimensions aswell as the spectral contentof emittedpulses during search, detection, and discrimination. The techniquecombines standardized test paradigms, and instrumentationpack carried by theanimal, and a positioningsystem. The animal's pack is a self-contained,data-acquisition system withsensors for magneticazimuth, acoustic emissions, attitude, and motion. It is basedon a high-speed,real-time microprocessor with opensoftware architecture for maximumflexibility. The positioningsystem employs a high-accuracyreal-time differential GPS for prepositioningtargets and monitoring the position of theboat and animal during a search. ContributedPapers 4:40 computedin timeincrements of 1/bandwidth.Echo features of thestandard andeach comparison target were analyzed in pairsby both a counterpropa- 4pAB9. Neural network modeling of a dolphin's sonar gationand a backpropagationneural network. The backpropagationnet- discrimination capabilities. Lars N. Andersen,A. Ren6 Rasmussen workperformed better than the counterpropagation network, and the use of (Tech.Univ. of Denmark,Lyngby, Denmark), Whirlow W. L. Au, Paul both time and frequencydomain feature• resulted in betterperformance E. Nachtigall (Hawaii lnst. of Marine Biol., Kailua, HI 96734), and HerbertRoitblat (Univ. of Hawaii, Honolulu,HI) thanif onlytime or frequency domain features were used. [Work supported by ONR, GrantNo. ONR N00014-93-1378.] The capabilityof an echo-locatingdolphin to discriminatedifferences in thewall thicknessof cylinderswas previously modeled by a counter- 4:55 propagationneural network using only spectralinformation of the echoes 4pAB10. Considerationsfor designing underwater acoustical [W.W. L. Au,J. Acoust. Soc. Am. 95, 2728-2735(1994)]. In thisstudy, playback experiments. William T. Ellison and Karen S. Weixel bothtime and frequency information were used to modelthe dolphin (MarineAcoust., Inc., 14 PelhamSt., Newport, RI 02840) discriminationcapabilities. Echoes from the same cylinders were digitized usinga broadbandsimulated dolphin sonar signal with the transducer The continuedhigh interestin the effectsof man-madesounds on mountedon the dolphin'spen. The echoeswere filteredby a bank of marinewildlife has resulted in increaseduse of playbackexperiments. In continuousconstant-Q digital filters and the energyfrom eachfilter was suchexperiments, the intent is oftento simulatea largermore powerful 3316 J.Acoust. Soc. Am., Vol. 96, No. 5, Pt.2, November1994 128thMeeting: Acoustical Society of America 3316 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp sourceof sound,e.g., a drillship, with a playbackof a recording,but using The automaticdetection of animalcells hasseveral potential applica- a smallportable source system such as a J-11 to play the soundback. tions:for range,distribution, and, censusefforts; for acousticbehavior Simulationaccuracy is assumedto be metin theseplaybacks if thereceive studies,both local and wide area;for screeningof largevolumes of datafor levelof thesound at theanimals being observed is thesame as they would soundsof interest.Methods were developedfor detectingthe vocalizations be exposedto by the full scalesource. To achievethis samereceive level of threespecies of mysticete:blue, finback, and minke whales. Each call is the playbacksource must often be movedto within shortrange of the modeledas a sequenceof eitherbandlimited pulses or frequencysweeps. animals.The purposeof this paperis to identify and discussthose com- ponentsof the actualfull scaleexposure that may not be accuratelysimu- Sweepsand pulses are detected by cross-correlatinga specially designed latedin an experimentwhere sound level at theanimal is theonly control kernelwith a spectrogramof the targetsound signal; the kernelis built variable.Components examined include the temporal, spectral, and spatial from the call model,and includesexcitatory regions corresponding to the propertiesof the noisefield, as well as the relativemotion of animaland sweepsor pulsesin the call, and flankinginhibitory regions to inhibit sourcewith emphasison the highlyvariable nature of the noisefield at responseto noiseand interfering sounds. This methodproduces as output shortplayback ranges. Recommendations are madeto assistexperimental a timeseries with valuescorresponding to the likelihood that the modeled designersin developingmore accuratesimulations. call is present.A time-windowedautocorrelation is then performed on this output,and the result of thatis percentlie-normalizedand thresholded. The 5:10 finaloutput is a yes/nodecision about the presence or absenceof a periodic sequenceof the desiredcalls. This processis currentlybeing used for 4pABll. Methodsfor automaticdetection of mystieetecalls. David K. Mellingerand ChristopherW. Clark (Bioacoust.Res. Prog.,Cornell scanninglarge amounts of sounddata from Navy SOSUSarrays; results of Univ., 159 SapsuckerWoods Rd., Ithaca,NY 14850) this scanningare presented. THURSDAY AFTERNOON, 1 DECEMBER 1994 SAN ANTONIO ROOM, 1:00 TO 5:00 P.M. Session4pEA EngineeringAcoustics: Transducers and Transducer Modeling R. Lowell Smith, Cochair TexasResearch Institute, 9063 Bee CavesRoaa• Austin, Texas78733 ElizabethA. McLaughlin,Cochair Naval UnderseaWarfare Center, New LondonDetachment, New London,Connecticut 06320 ContributedPapers 1:00 To producehigh amplitudelow-frequency signals, an underwatertrans- ducermust generate a relativelylarge volume displacement. Since water 4pEA1. Theoreticalmodel for a (3,1) drive low-frequencypiezofilm exertsa large reactionforce back on the transducer,"conventional wis- hydrophone.P. Philip Thomson (Dept. of Appl. Phys.,School of Phys., dom" dictatesthat sucha transducerwould have to be a high Q resonant Univ. of New SouthWales, Sydney 2052, Australia) deviceand thusnot be broadbandas seeminglyrequired for many appli- An innovative(3,1) drive transducerdesign has been discussed in the cations. However, a transducerdoes not have to be broadband in the con- literature[J. J. Bhatt,P. P.Thomson, and P. R. S Pillai,J. Acoust.Soc. Am. ventionalsense to work in communicationand SONAR systems.A trans- 94, 3053-56 (1993)]using a poledpiezofilm adhered to a driverpin which ducercapable of switchingbetween two discretefrequencies is adequate is fixed to the centerof a rigidly clampedcircular plate. This paperat- for communicationand one capableof switchingamong several frequen- temptsto analyzethe abovetransducer for a particularfrequency range in ciescould produce chirp signals for activesonata. Ordinarily, a broadband termsof the theory of transversevibrations of a clampedcircular plate transduceris neededto switchfrequencies rapidly. It is theoreticallypos- carryinga concentratedmass at itscenter [R. E. Roberson,J. Appl.Mech. sible,however, to instantaneouslyswitch frequencies with a high Q reso- 18, 349-352 (1951)].The systemsatisfies the requirements for vibrational nantsystem provided that the system'sresonant and drive frequenciesare analysisand the naturalfrequencies can be estimatedfrom abovetheory. A alteredsimultaneously. Such a "state-switched"transducer [Munk, Webb, statisticalapproach is madeto calculatethe theoreticalsensitivity below Birdsall,unpublished (1980), (1981)] would retain the advantages(high resonance.The prestretchedpiezofilm acts as a longitudinalvibrator with power,high efficiency,and largedisplacements) of a high Q resonant the electricfield perpendicularto its lengthand the transducersystem can transducerwithout the accompanyingdisadvantage of slowresponse time. be representedby a six-terminalnetwork with an electricalinput voltage A state-switchedacoustic source with an activespring of PZT has been drivingthe mechanicalload acting only on oneedge of the piezofilm.The built to demonstratethe stateswitching concept. [Research supported by surfacestrain developedin the diaphragmin responseto the acoustic ONR 334.1 pressureand electroacoustic sensitivity are evaluated by thinplate theory and piezoelectrictheory. The calculatedvalues are in agreementwith ex- perimentalresults. 1:30 4pEA3. A planar-omnidirectional sensor for broadband and high-frequency underwater acoustic al•01ications. Thomas R. 1:15 Howarth, Sam Petrie, and Larry E. Ivey (Naval Res. Lab., Underwater SoundReference Detachment, P.O. Box 568337, Orlando,FL 32856-8337) 4pEA2. State switched acoustic source. Gregg D. Larson and Peter H. Rogers (Schoolof Mech.Eng., Georgia Inst. of Technol.,Atlanta, GA A prototypehydrophone with planar-omnidirectionalradiation charac- 30332-0405) teristicshas been developedfor broadband,high-frequency, underwater 3317 d. Acoust. Soc. Am., Vol. 96, No. 5, Pt. 2, November 1994 128th Meeting: Acoustical Society of America 3317 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp acousticapplications. A 9-/.tmsheet of KYNAR-typepolyvinylidene fluo- A superiorunderwater projector having low frequency,high power, ride(PVDF) was wrapped about a 2.5-mmsolid Rho-c rod with a height highefficiency, and broad bandwidth for the Ocean Acoustic Tomography of 86 mm suchthat the resultingcylindrical shape had an omnidirectional (OAT)system has been developed. The OAT system is proposedto mea- radiationbehavior in theX-Y plane.The PVDF wasoriented with the 3-1 suretemperature and current distributions of a widerange of seaarea with directionradially wrapped and the 3-2 axispositioned along the mounting a diameterof about1000 km on real time by usingsound waves. The rod for improvedvibration strum rejection from the mountingrod with projectorvibrates in the radialmode of octagonalradiating plates con- improvedradial sensitivity because of the orthotropicnature of the KY- nectedwith eightdriving units having giant magnetostrictive rods. The NAP,material. Further discussions will detailthe selectionof an imped- projectoris ableto emitsound of morethan 190 dB [0 dB=l /.tPa-m]at a ancematching mounting rod and waterproofing elastomer and a cablewith lowfrequency of about200 Hz underthe operation depth of about1000 m the low capacitanceof 0.018pF/m (8.5 pF/ft). Measureddata to be shown whenit is excitedby electricinput power of about900 W. The perfor- includesthe free-field voltage sensitivity (FFVS) and X-Y planereceiving manceis enoughto coverthe range of 1000km for theOAT system. Also, radiationpatterns from 100 kHz to over 1.5 MHz. The presentationwill the derivedvalues from measurementsare in goodagreement with the concludewith a conceptualdiscussion on an advancedversion of thissame calculationsbased on the simpleequivariant circuit model. sensordesign for a broadbandand high-frequency, three-dimensional om- nidirectional sensor. 2:30 1:45 4pEA7.A reexaminationof modecoupling and lossPhenomena for simple piezoelectricoscillators. R. Lowell Smith (TexasRes. Inst., 4pEA4. A miniature, high-sensitivity, electron-tunneling 9063 Bee Caves Rd., Austin, TX 78733) accelerometer. Thomas B. Gabrielson (NAWC Aircraft Div., Code Applicationsof bothlinear and nonlinear theories of piezoelectricityto 5044, Warminster,PA 18974-0591), HowardK. Rockstad,and Tony K. transductionproblems commonly ignore internal material dissipation ef- Tang (Ctr.for SpaceMicroelectron. Technol., Pasadena, CA 91109-8099) fects.Such losses can be representedphenomenologically via the intro- A prototypelow-noise accelerometerhas been fabricated with an ductionof complexdielectric, elastic, and piezoelectric coefficients. How- electron-tunnelingtransducer. By measuringthe tunneling current between ever,there is someconfusion in theliterature with respect to theproper an electrodeon the proof massand a feedback-controlledmonitor elec- partitioningof electricaland mechanical attributes in thepresence of pi- trode,very small accelerations can be detected with high responsivity. This ezoelectriccoupling. This paperis a reviewof thissituation wherein dis- particularprototype (10X10X1.5 mm} was designedfor underwater sipationcoefficients are motivated from more fundamental physical in- acousticmeasurement from a few hertzto 1 kHz.The measured respon- sights.Equivalent circuit models are usefulboth for developingthis sivitybelow the fundamental device resonance at 100 Hz is roughly1500 perspectiveand summarizing the results.Suggestions are also presented V perm/s 2with a measurednoise spectral density of 10-6 m/s2per root for generalizingthe celebrated Mason model to includethe coupling of hertzor lessbetween 30 and300 Hz. Thenoise floor is controlledprima- orthogonalmodes via Poissondilation. This formalism is intendedto pro- rily by 1/f noisein thetunneling current although the noise floor reaches videstraightforward procedures forcomputing piezoelectric oscillator per- thetheoretical molecular-agitation limit at 100 Hz. The responsivityand formancecharacteristics using a personalcomputer. The approach isevalu- directivityof thedevice were measured in a standardgradient-hydrophone atedvia regression analysis in termsof itsself-consistency forinterpreting calibrator; the noise floor was determined in a vacuum-isolation chamber Tonpilzoscillator admittance data. The procedures developed are expected assembledfrom commercialoff-the-shelf components; and the detailed to be applicablefor theinterpretation of data associated with a varietyof dynamicsof theproof-mass motion were examined using a heterodyne other electroacoustic structures. laserinterferometer that was scanned across the surface and synchronously detectedwith respectto theexcitation. [Work supported by ONR.] 2:45 2:00 4pEA8. Somesecond thoughts on electromechanicalcoupling. Li-FengGe (AnhuiBureau of Tech.Supervision, 30 Ma An ShanRd., 4pEA5. The improvementof low-frequencydriver performance Hefei,Anhui 230001, People's Republic of China) usingan amplifier with negativeoutput resistance.Thomas D. Kite An electromechanicaltransducer can be regardedas an energycon- andElmer L. Hixson (Dept.of Elec.and Comput. Eng., Univ. of Texasat verter,and also as an impedanceinverter. It couldbe significantfor un- Austin, Austin, TX 78712) derstandingthe transruction process to introducea newgeneralized con- A low-frequencydynamic driver (woofer) was modeled on PSPtCE,an cept,inversive impedance, which is definedas a ratioof theopen-circuited electriccircuit simulator. The far-field pressure response ofthe driver was voltagecaused by a motionat the mechanicalend of a transducerto the computedas the dc resistance ofthe voice coil, Re, wasvaried. In thelimit excitingcurrent required to producethe same motion, i.e., a ratioof the of zeroRe, theon-axis response for a constantvoltage input was shown to receiving(voltage) sensitivity of a transducertoits sending (current) sen- riseat 6 dB/octave.The input to thedriver was therefore equalized with an sitivity.Thus the electricaldriving-point impedance is composedof an integratorto producea flatpressure response with frequency. A beneficial impedancewithout coupling and a inversiveimpedance, which is induced sideeffect of reducingRe wasthe improvement of the transient response byelectromechanical coupling, and is constantat a givenfrequency for a of thedriver, since it becamepossible to criticallydamp the system. The particulartransducer. The transruction process or theimpedance inversion systemwas foundto be stablefor valuesof R e greaterthan zero. The processcan be describedby onlythree independent parameters [L.-E Ge, simulatedresults were tested in an anechoicchamber using a poweram- J. Acoust.Soc. Am. 91, 2326(A) (1992)],and determined uniquely by a plifierwith variable negative output resistance. The far-field pressure re- mappingbetween the electrical driving-point impedance and its mechani- sponseof thedriver wag found to be substantiallyfiat overa broadrange cal loadimpedance. It is an inherentphysical property independent of of frequenciesaround the naturalresonance of the driver, and transient analogy-typechosen and mathematical representatio n that a piezoelectric- responsewas improved,as predictedby the circuitsimulation. typetransducer is reciprocal,and an electrodynamic-typetransducer is antireciprocal.Thus there exists, respectively, anoptimum way to perform reciprocitycalibration for thetwo typesof electromechanicaltransducers. 2:15 4pEA6.A low-frequencyprojector using giant magnetostrictive rods. 3:00-3:15 Break AkiyoshiKawamori, Takashi Yoshikawa, Tomohiro Tuboi (OKI Electric IndustryCo., Ltd., Electron.Syst. Lab., 688 Ozuwa, Numazu-shi, 3:15 Shizuoka,410 Japan), Iwao Nakano,Toshio Tsuchiya, and Tosiaki Nakamura (JapanMarine Sci. and Technol.Ctr., Yokosuka-shi, 4pEA9.Variational model for the radiationimpedance of classIV Kanagawa,237 Japan) transducers.Harold C. Robinsonand Elizabeth A. McLaughlin(Naval 3318 J.Acoust. Soc. Am., Vol. 96, No. 5, Pt.2, November 1994 128thMeeting: Acoustical Society ofAmerica 3318 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp Undersea Warfare Ctr., New London Detachment, New London, CT homogeneousisotropic elastic formation of infiniteextent without restric- 06320) tiveassumptions on thegeometry, radiation pattern, or typesof waves.The finite elementmethod is well suitedto solve suchproblems if the tronca- In a previouspaper [H. C. Robinson,J.Acoust. Soc. Am. 95, 2833 (A) tureof the infiniteformation is correctlytreated. This troncaturegenerates (1994)],a variationalmethod for determiningthe modalradiation imped- ingoingwaves which normallydo not exist in infinitedomain. In this anceof baffledtransducer arrays, based on the radiatedpower, was pre- paper,classical finite elements (^TtC^ code) are used to modelin steady sented.In thispaper, these variational methods will be extendedto include statethe transducer,the fluid-filledborehole, and part of the formation unbarfledarrays of radiatorswith arbitraryspatial orientation. The surface insidea sphericalboundary. On thisexterior boundary, impedance ele- velocityof eachof the radiatorsis representedby in vacuoeigenmode ments are used to take into account the infinite character of the formation. expansions,while the surfacepressure is givenby expansionsin suitable Theseelements are obtained by discretizingthe mechanicalimpedance of trial functions.The arbitraryorientation of the array elementswill be outgoingspherical P andS waves.The methodis validatedby studying representedby transformingthe surfacevelocities and pressuresusing twoconfigurations having analytical solutions: the pulsating sphere and the Eulerangles. As a specificexample, the caseof two coplariatclass IV oscillatingpoint. Results include displacement fields and radiation patterns flextensionaltransducers will be examinedin detail.The in vacuoeigen- for P or/andS waves.Finally, the radiationof a cylindricalpiezoelectric modesof a singleelement will be determinedusing finite element methods transducerin an oil-filled borehole[S. Kosteket al., J. Acoust.Soc. Am. andparametrized in ellipticalcylindrical coordinates (•,•/,z). The surface 95, 109(1994)] is analyzed.P andS componentsof thedisplacement field, pressuretrial functions will be judiciouslychosen functions of (•,•,z) as electricaladmittance of the transducer,directivity patterns, and distribution well. The behaviorof the modal radiationimpedances as a functionof of radiatedenergy are displayed. dimensionlessseparation distance kd, as well as of relativeorientation, will be investigated.Comparisons of the resultsto equivalentcircuit mod- elsand experimental data will bepresented. [Work sponsored by ONR.] 4:15 4pEAl3. Thermodynamic property considerationsfor modeling 3:30 piezoelectricceramic vibrators including thermal effects. Won-kyu Moon and11ene J. Busch-Vishniac(Mech. Eng. Dept., Univ. of Texasat 4pEA10. The combined finite element and hybrid-type infinite Austin,Austin, TX 78712) element analysis for complex structure underwater transducers. Jong-RakYoon and Chun-Duck Kim (Dept.of TelematicsEng. and Dept. The thermodynamiccharacteristics of piezoelectric ceramics are inves- of Elec.Eng., Natl. Fisheries Univ. of Pusan,Pusan, Korea 608-737) rigatedby consideringtwo thermodynamic material property models: isen- tropicallylinear and isothermally linear models. Those two models are two A numericalmethod for evaluatingthe electroacoustical characteristics possibleinterpretations of the data on temperature-dependentlinear coef- of a complexstructure of transducerimmersed in an infiniteacoustic me- ficientsof piezoelectricceramics. Thermodynamic differences of the two diumis adopted.The mechanical,electrical, and acoustical response of the models are examined and effects of the thermo-electro-mechanical cou- transducerin thefinite region is modeledby thefinite element method; the plingsare evaluatedin examples.Application of the thermo-electro- Sommerfeldradiation condition to the infiniteregion is modeledby the mechanicalmodel to PZT4 showsthat the differenceobserved in piezo- hybrid-typeinfinite element method, and the boundarybetween both re- electricconstants obtained by staticand dynamic measurements cannot be gionsis formulatedwith compatibility of theacoustical admittance in both explainedby the differencebetween isothermal and isentropic processes. regions.The numericalresults, which includethe elasticresponse, the radiationimpedance, and the input electricaladmittance, are given for a singlepiezoelectric cylinder and a coaxialtwo piezoelectriccylinder array 4:30 with variouspolyurethane windows. The techniqueallows one to interpret andto optimizedesign parameters such as geometrical shape and mechani- 4pEA14.Bond graph modelfor one-dimensionalheat conductionfor cal propertiesof structurecomponents, electrical characteristics of piezo- modeling of piezoelectric ceramic vibrators including thermal electric elements, etc. effects. Won-kyuMoon and Ilene J. Busch-Vishniac(Mech. Eng. Dept., Univ. of Texas at Austin, Austin, TX 78712) 3:45 A newbond graph model for conductionheat transfer is developedand appliedto considerationof thermal energy balance in the piezoelectric 4pEAll. Widebandarray transducer. Chun-DuckKim andJong-Rak thicknessvibrator. In formulation of the model, the mechanical and elec- Yoon (Dept.of Elec.Eng. and Dept. of TelematicsEng., Natl. Fisheries tricaleffects are included,so it canbe applieddirectly to the temperature- Univ. of Pusan,Pusan, Korea 608-737) dependentthickness vibrator. Although the analysisis appliedto theone- Thereis a needto developa widebandunderwater sound source. This dimensionalcase only, the method can be usedfor generalheat conduction needcan be accomplished by anarray of differentresonance frequencies of problems.For the purposeof evaluationof the new method,the model transducers.An axisymmetricarray transducer, which consists of three predictionsfor one-dimensionalheat conduction excluding other variable differentsize piezoelectriccylinder elements, is designedand its coupled effectsare comparedwith the resultsof the analyticsolutions in simple electrical,mechanical, and acousticalcharacteristics are evaluatedusing cases.The simulationillustrates the validity and the accuracy of themodel. thecombined single code finite element method and hybrid-type infinite element method.The numericalresult of electricalinput impedanceis consistentwith the measurementresult using an impedanceanalyzer and is 4:45 shownto be betterthan that by WarrenP. Mason'sequivalent circuit modelingmethod. Its bandwidthand directivity pattern are alsoobtained 4pEA15. Coolinglow-frequency sonar projectorsby heat transfer and its limits as underwatersound projector are discussed. optimization. BertrandDubus, Patrice Bigotte (Inst.d'Electron. et de Micro61ectron.du Nord, UMR-CNRS 9929, D6pt. ISEN, 41 boulevard Vauban,59046 Lille Cedex,France), Gilles Grosso (Eramet,83500 La 4:00 Seynesur Met, France),and DidierBoucher (DCN-lng6nierie Sud, 4pEA12.Coupling finite elementand impedanceelement to model 83140Six Foursles Plages,France) the radiation of piezoelectrictransducers in boreholes. Didace Heatinghas become a criticalissue for low-frequencyprojectors due to Ekeomand Bertrand Dubus (Inst.d'Electron. et de Micro61ectron.du theirhigh dissipated power density and long e•eitation time. In thi• paper, Nord,UMR CNRS9929, D6pt.ISEN, 41 boulevardVauban, 59046 Lille the coolingof sonarprojectors in termsof heattransfer optimization is Cedex, France) presented.An analysisof theprojector heating requires the description of In thecontext of petroleumacoustics, it is of greatinterest to modelize the heat conductionin the structureand the heat exchangeswith the sur- theradiation of thepiezoelectric transducer in a boreholesurrounded byan roundingmedium. This analysis is performedin steadystate using both 3319 d. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3319 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp analytical(thermoelectrical analogies) and numerical (finite element) mod- determinethe optimalsolution. At constantdissipated power density, the els. For the referencetransducer (double-ended longitudinal piezoelectric maximumtemperature is theoreticallydivided by 3. Temperaturemeasure- vibrator),the temperaturedistribution and heat fluxes are computed.The mentson referenceand optimized projectors are provided and compared to temperaturedecrease and the importanceof variousheat paths are evalu- predictions.Extension of the techniqueto othergeometries of projectors atedfor varioustechniques of cooling.Practical considerations (simplicity, andother types of activematerials (magnetostrictive, electrostrictive) is fiability,cost, size) and cooling efficiency are bothtaken into accountto discussed. THURSDAY AFTERNOON, 1 DECEMBER 1994 PECOS ROOM, 1:00 TO 5:30 P.M. Session4@PAa Physical Acoustics:Nonlinear Acoustics Oleg V. Rudenko,Cochair Departmentof Acoustics,Physics Faculty, Moscow State University, Moscow 119899, Russia E. A. Zabolotskaya,Cochair Departmentof MechanicalEngineering, The Universityof Texasat Austin,Austin, Texas 78712-1063 ContributedPapers 1:00 sinceV&=-n&.0, it is foundE]2(•rd,)=2%r-V&-2•0&.0=-2•P.0X.0, leadingto the solutionof Eckart'sequation, psc•=(2-A)V•2-Ei2 4pPAal. Nonscatteringof sound by sound resulting from a head-on +2[(2+A)o'&-•b2].00,valid within the interaction zone, but vanishing collisionof two plane-wavepulses. PeterJ. Westervelt(Dept. of Phys., oulsidewhere V• = E •2= •r= •b= •b'=0.The feasibilityof makingoptical Brown Univ., Box 1843, Providence,RI 02906) measurementsof ps is being investigated. Twoarbitrary pulses p2(t - ½o•x) andp i(t + c• Ix) eachof widthc0•- passthrough one anotherat x=0, generatinga differentialsurface mass 1:30 rate sourcedensity d•rs(t,x)=qs dx where qs=Ad(plp2)/dt and A = (p0c•)-l[2+ poCg2 (d2 p/dp2 )t•o]' The equation forthe scattered pres- 4pPAa3. Critidsm of experimentson the scattering of sound by sure Ps is dZpsldxZ-c•2 d2P• Idt•=-Os and its solutionis sound. D. H. Trivett (Naval Res. Lab., UnderwaterSound Ref. Det., ps(X',t)=J'dp•=(c•12)J'd•s=(co/2)J'q•(x,t')dx,t' being the retarded P.O. Box 568337, Orlando,FL 32856-8337) and Peter H. Rogers time;thus, (p•). = (Co/2)A•co•l:[d(p•p2),-,,ñIdt]dx,where + is (GeorgiaInst. of Technol.,Atlanta, GA 30332-0405) chosenwhen x' 1:15 The questionof whetherone soundbeam can interactwith anotherat noaz.•roangl• and acatt•r nonlinearlygenerated sound oulside the mutual 4prAa2. •cattenng o[ sound by souncl wit#in the interaction zone. PeterJ. Wearerreit(Dept. of Phys.,Brown Univ., Box 1843,Providence, interactionregion has been debated since the 1950s.Experimental work on RI 02912) thisproblem has left the questionunresolved. This presentationdescribes experimentaldifficulties associated with measuringscattered sound pro- Startingwith Eckart'sequation for p• thescattered density [P. I. West- ducedby realdiffracting primary beams. Optimal conditions for observing ervelt, J. Acoust.Soc. Am. 29, 934 (1957)], scatteredsound, as outlinedby Bemtsenet el. [J. Acoust.Soc. Am. 86, -V2(2T12+AV•2),the variables xø=Co t and•.o--(4poco) - 2 -• p are 1968 (1989)] and by Darvennesand Hamilton [J. Acoust.Soc. Am. 87, introduced for which EI2O=0, 1•12•2=Ti2-- Vi2 , and 1955(1990)], are reviewed in relationto thedesign of our ownexperi- V2Vi2=[•2V12 + (V12).00 to obtain [32[psc•+Ti2+(A-1)V•z ments.Our experimentswere performedwith either two uniformcircular +2(02).00]=-2(2+A)[(0.0)2].0o.Nextit is assumedthat O=&+X, where sourcesin water(megahertz frequencies), or with one circularsource and ,;b(xø-n.r)is a planewave and X.o=O-.0+n-%r, where a(xa,r) is an arbi- the other a shadedsource with lower sidelobes.A variety of primary trarywave. Terms bilinear in •band X areretained; thus 0p0)2=2X.04•.0, and frequencyratios, interaction magics, and other parameters were considered. 3320 d. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3320 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp Comparisonof the primarybeam patterns with measuredsum and differ- weak shocktheory can be usedto separatethe descriptionof the shock encefrequency field patternsreveals the difficultyin identifyingwhich frontsfrom the evolution of thecontinuous segments of thewave. The idea componentsof the lattercorrespond to "scattered"sound. It is concluded of thepresent work is to modifythe spectral method by takinginto account that two Gaussian-typesources with exceedinglygood sidelobe suppres- the knownasymptotic behavior of high-frequencycomponents in shock sionare needed to performa reasonableexperiment. [Work supported by waves.Use of asymptoticresults permits the numberof spectralcompo- thePackard Foundation and ONR.] alPresent address: Earth and Environ- nentsretained in the numericalcomputations to be reduced.A finiteset of mentalSciences Division, Mail StopD443, LosAlamos National Labora- coupledequations for the spectralamplitudes, which approximatesthe tory, Los Alamos,NM 87545. infiniteset of spectralequations corresponding to an exactformulation, is obtainedfor the simplewave equation.This reductionis achievedby introducingasymptotic expressions for thehigh-frequency components in 2:00 sawtoothlikewaves. Several model problems are studied.It is shownthat 4pPAa5. Analytical method for describing the paraxial region of lessthan 15 harmonicsrequire numerical calculation in orderto obtainan finite amplitude sound beams. Mark F. Hamilton (Dept. of Mech. adequatedescription of the evolutionof an initially sinusoidalwave to a Eng., Univ. of Texas at Austin, Austin, TX 78712-1063), Vera A. sawtoothlikewaveform. [Work supported by ISF andthe Russian Fund for Khokhlova,and Oleg V. Rudenko (MoscowState Univ., Moscow 119899, FundamentalInvestigations.] Russia) The paraxialregion of finiteamplitude sound beams in losslessfluids is studiedtheoretically. Both focused and unfocused beams are considered. 2:45-3:00 Break A specialanalytical method which combines the parabolicapproximation (KZ equation)with nonlinear geometrical acoustics (NGA) is developedto model nonlinear and diffraction effects near the axis of the beam. The 3:00 correspondingsystem of nonlinearequations describing waveform evolu- tion is derived.For the caseof an initially sinusoidalwave radiatedby a 4pPAaS.Generation of streamingand rarefactionof the gas in the Gaussiansource, an analyticalsolution of the coupledequations is ob- far field of the weakly nonlinear plane waves. Takem Yano and tainedalong the axis of the beam.The solutionis expressedin both the YoshinoriInouc (Dept. of Eng. Sci., Hokkaido Univ., Sapporo060, time and frequencydomains. In the high-frequencylimit, classicalsimple Japan) wavesolutions are recovered(plane-wave solution for unfocusedbeams and sphericalwave solutionfor focusedbeams). In the limit of weak The propagationof weaklynonlinear plane waves emitted from a har- nonlinearity,the quasilinearaxial solutionsof the KZ equationfor the monicallyoscillating plate into an idealgas of semi-infiniteextent is con- fundamentaland second-harmonic components are recovered.The analyti- sideredunder the conditionthat the energydissipation is negligiblysmall cal solutionis in good agreementwith numericalsolutions of the KZ everywhereexcept for discontinuousshock fronts. Recently, the authors equationfor a wide rangeof ratiosbetween the focal length,Rayleigh have numericallyshown that, in the caseof stronglynonlinear waves, distance,and shockformation distance. Harmonic propagation curves, contraryto theresult of theconventional weakly nonlinear theory, stream- waveformdistortion, focusing amplification factors, and othercharacteris- ingdue to shocksoccurs in thedirection of wavepropagation and thereby ticsare calculated. [Work supported in partby NATOand ISF.] thegas near the source is rarefiedas time proceeds [Y. Inoueand T. Yano, J. Acoust.Soc. Am. 94, 1632-1642(1993)]. In the presentpaper, the evolutionof theweakly nonlinear waves including shocks is determinedup 2:15 toO(M2), where M isthe acoustic Mach number (M'•I). In thisorder, the 4pPAa6. A study of the role of diffraction in the behavior of waveprofile develops to an asymmetricalsawtoothlike one in thefar field focusing step shocks using NPE-type equations and a finite andweak streaming is excitedin the regionbeyond the shockformation differenceprogram. AndrewA. Piacsek (GraduateProg. in Acoust., distance.For M•<0,2, the resultsquantitatively agree with thosein the PennState Univ., P.O.Box 30, StateCollege, PA 16804) previouswork. Furthermore, bytaking into account both the production of entropyand the generationof reflectedwave at eachshock front, the A finitedifference solution to an NPE-likeequation is usedto studythe physicalmechanism isclarified for the rarefaction ofthe gas in O(M3). linearand nonlinearbehavior of focusingstep shocks in regionswhere causticsare formed.The initial conditionis a nominallyplane step pulse with a hyperbolictangent rise profile of thicknessl•n; thewavefront has a 3:15 singleripple of lengthscale Lwf, concavetowards the directionof propa- gation.When •=l•n/Lwf is much less than unity, the linear numerical 4pPAa9. Prediction of the time-averagedpressure distribution for simulationshowed that the shockbehaves nearly according to geometric finite amplitudestanding waves. Reh-linChen and Victor W. Sparrow theory.Several different values of • were investigated,verifying the linear (GraduateProg. in Acoust.,Penn State Univ., 157 HammondBldg., theorypredictions of normalized amplitude _e-l/4 at thecusp [J. Hunter UniversityPark, PA 16802) andJ. Keller,Wave Motion 9, 429-443 (1987)]. Numericalsolutions are alsoobtained for threecases of nonlinearpropagation with dissipation.In A finite differencenumerical approach to studyingtwo-dimensional additionto e, the distinguishingparameters are shockamplitude and dis- nonlinearwave propagation was recently developed IV. W. Sparrowand R. sipation.It is observedthat for casesin whichnonlinearity is stronger Raspet,J. Acoust.Soc. Am. 90, 2683-2691(1991)]. In thistalk the ap- relativeto diffractionand focusing, the wavefrontforms a cuspat a later proachis modifiedand appliedto a one-dimensionalfinite amplitude time, causticsare lesspronounced, and the (normalized)rise time is standingwave in a rigidtube. The numerical method can solve for lossless, shorter.Implications of theseresults on the effectof causticson sonic weaklynonlinear waves in thetube including all second-ordernonlineari- boom rise times is discussed. tiesfrom the continuity equation, momentum equation, and the equation of state.The acousticpressure in thetime, space, and frequency domains and the time-averagedacoustic pressure distribution are all determined.Gen- 2:30 erationof harmonicsof the fundamentalfrequency along with the devel- opmentof a nonzero,time-averaged pressure are seen from discrete Fou- 4pPAa7. Modification of the spectral method for describing rier transformsof the numericalresults. The resultsfor the time-averaged nonlinearacoustic waves containing shocks. VeraA. Khokhlovaand pressuredistribution are compared to recentanalytical predictions [C. P. OlegA. Sapozhnikov(Dept. of Acoust.,Phys. Faculty, Moscow State Lee andT. G. Wang,J. Acoust.goc. Am. 94, 1099-1109(1993)]. The Univ., Moscow 119899, Russia) resultsshow agreement between the presentwork andthat of Lee and Numericalsimulations of finite amplitudesound waves becomepar- Wangwhen the nonlinearitiesfrom both the momentumequation and ticularlytime consuming in thecase of stronglydistorted waveforms that equationof stateare included. A slightlydifferent result is obtainedwhen containshocks. To improvethe efficiency of timedomain numerical codes, one alsoincludes nonlinearity from the continuityequation. 3321 d. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128th Meeting:Acoustical Society of America 3321 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 3:30 onthe original frequency domain equations. [Work supported by thePack- ard Foundation,ONR, andNSF.] 4pPAa10.Extensions of the theory for nonlinearRayleigh waves. E. Yu. Knight,M. F. Hamilton,%. A. U'insky,and E. A. Zabolotskaya (Dept.of Mech.Eng., Univ. of Texasat Austin,Austin, TX 78712-1063) 4:15 The derivationof Zabolotskaya'scoupled spectral equations for non- 4pPAa13. Theoretical model for nonlinear StoneIcy and Scholle linearRayleigh waves in isotropicsolids [J. Acoust.Sac. Am. 91, 2569 waves. G. DouglasMeegan, Mark E Hamilton, and E. A. Zabolotskaya (1992)] appliesto plane,progressive, periodic waves. These assumptions (Dept.of Mech.Eng., Univ. of Texasat Austin,Austin, TX 78712-1063) are removedhere in a moregeneral derivation based on the Hamiltonian The Hamiltoninnformalism used previously to derivemodel equations formalismemployed in theoriginal work. Via methodsdescribed in Paper for nonlinearRayleigh waves [Zabolotskaya, J.Acoust. Soc. Am. 91, 2569 4pPAa12of thissession, the resultingspectral equations are transformed (1992)]is usedhere to obtaina mathematicalmodel for nonlinearStoneIcy into time domainevolution equations. Model equationsfor cylindrical and SohoItcwaves. Planar interfaces formed by contactbetween two iso- wavesand diffracting beams, obtained previously via ad hocmodification tropicmaterials are assumed. The resultingcoupled spectral equations are of theplane-wave model, can be derivedrigorously from the new gener- expressedin the sameform as those for Rayleighwaves. In particular,the alizedequations. The nonlinearterms are shown to be equivalentto those nonlinearitycoefficient matrix can be written as R•t = R(tnl•+ KR•, where obtainedpreviously by Parker [Int. J. Eng.Sci. 26, 113(1985)] by entirely different methods. Numerical results for the shock formation dislance are K is a constantand R•t (correspondingto medium i=1,2) arematrices havingthe samemathematical form as the matrix obtainedfor Rayleigh usedto definean effectivecoefficient of nonlineadtythat is consistentwith waves.Since R[t exhibitsthe same symmetries asthe nonlinearity matrix the correspondingparameter for soundwaves in fluids.The coefficientis for Rayleighwaves, the modelequations for StoneIcyand SohoItcwaves of orderone for commonisotropic solids, as for the caseof fluids,but it is can be analyzedwith the samemathematical techniques that havebeen severalordem of magnitudelarger in rock with microcracksand other employedin recentinvestigations of nonlinear Rayleigh waves (see, e.g., inhomogeneousfeatures. [Work supported by DOE,ONR, and NSF.] otherpapers in thissession). The coupledspectral equations were solved numericallyfor StoneIcyand Scholtewaves at interfacesformed by a 3:45 varietyof mediapairs, including some geological materials. Comparisons of harmonicgeneration and shockformation are madewith the corre- 4pPAall. Pulsed nonlinear Rayleigh waves. E. Yu. Knight, M. F. spondingprocesses in Rayleigh waves. [Work supported by AASERT and Hamilton,and E. A. Zabolotskaya(Dept. of Mech. Eng.,Univ. of Texas ONR.] at Austin,Austin, TX 78712-1063) Pulsed,plane, nonlinear Rayleigh waves in isotropicsolids are inves- 4:30 tigatedwith numericalsolutions of thecoupled spectral equations derived by Zabolotskaya[J. Acousl.Soc. Am. 91, 2569(1992)]. Calculations of 4pPAa14, Observations of nonlinear effects associatedw'th ice waveformevolution are presented as functions of distancefrom the source cracks. Lev A. Ostrovsky,a) Alexander Ekimov, Alexey Korotkov, anddepth within the solid. For the case of weaknonlinearity (characteristic AudreyLebedev, and Alexander M. Sutin (Inst.of Appl. Phys.,Nizhni absorptionlength on the orderof the shockformation distance), self- Novgorod,Russia) demodulationof tone burstsis investigated.Self-demodulation refers to The hypothesisthat cracksin ice may provideanomalously strong the nonlineargeneration of a low-frequencywaveform by a high- acousticnonlinearity is experimentallyverified. Two seriesof experiments frequencypulse. Comparisons are madewith the analogousprocess in were performed.One of them was done in situ, on a freshwaterlake fluids.Whereas demodulated Rayleigh and acoustic waveforms have simi- coveredby a 40-era-thickice. Flexuralwaves were excitedin ice by a lar shapes,the demodulatedRayleigh waveforms have substantially vibratorin frequencyrange 0.2-2 kHz andreceived by accelerometers.Air smallerrelative amplitudes.The differencein amplitudeis due to the temperaturewas -5 and +3 øC for two differentseries of measurements. frequencydependence of the nonlinearitycoefficient matrix for Rayleigh A high level of nonlinearitywas registered.In particular,a pronounced waves.For the caseof strongnonlinearity, shock formation is investigated subharmonicsignal was generated which testifies for parametricinstability. in a variely of transientwaveforms. Via comparisonwith acousticwave- The secondexperiment was performedin laboratoryconditions, when a form evolutionin fluids,precursors generated by certainRayleigh wave- "crack"was created artificially, as a contactbetween two piecesof ice.We formsare identified as consequences of nonlocal nonlineatity. [Work sup- studiedmodulation of ultrasound(about 26 kHz) by tow-frequency(30-90 portedby DOE, ONR, andNSF.] I/z) vibrations.For vibration acceleration amplitudes up to 0.1 and0.3 g a pronouncedmodulation spectrum appeared; moreover, modulation fre- quencysubharmonics were observedin this case.Some theoretical con- 4:00 siderationsof the effectsobserved are alsogiven. It is believedthat non- 4pPAa12. Evolution equations for nonlinear Rayleigh wave lineareffect can be effectively used for Arctic ice characterization. a•Now propsgat'on. M. F. Hamilton, Yu. A. II'insky, and E. A. Zabolotskaya at Univ. of Colorado,CIRES, ETL/ERL/NOAA, 325 Broadway (Dept.of Mech.Eng., Univ. of Texasat Austin,Austin, TX 78712-1063) Boulder, CO 80303. Time domainevolution equations are derivedfor nonlinearRayleigh wavepropagation along the free surfaceof an isotropicsolid. The evolu- 4:45 tion equationsare expressedin differentforms: one for the horizontal 4pPAa15.Diffusing light photographyof solironsand capillary-wave displacementcomponent, and one for a complexdisplacement variable. •urbulence. W. Wright,R. Budak,and S. Putlerman(Phys. Dept., Both equationsare derived from spectralequations published earlier UCLA, LosAngeles, CA 90024) [Zabolotskaya,J. Acoust.Sac. Am. 91, 2560 (1992)].To simplifythe derivationof equationsfor the displacementvariables, not all components The attenuationof lightpropagating through a slabof wa•r (contain- of the nonlinearitycoefficient matrix are retained.However, the terms ing a diluteconcentration of polyballs)is approximatelyproportional to its whichare retainednnr. qe.•q the namemathematir'al nrt•nort;•c (symmetries thickness.Application of this insightto the local elevationof a fluid sur- in the frequencydomain, singularities in the timedomain, and others) as face has enabledus to use photographyto determinethe instantaneous the termsthat are not takeninto account.Moreover, with appropriatedefi- globaltopography of thesurface of a fluid in motion.Use of diffusinglight nition of the shock formation distance, it is shown that numerical solutions enablesus to obtainimages that are free of the causticswhich plague basedon the simplifiedequations yield close agreementwith numerical shadowgraphs.Applications include breather soiltons and wave mrbulcuce solutionsbased on the completenonlinearity matrix. The nonlinearterms which resultsfrom the nonlinearinteraction of a broadbandspectrum of in the new evolutionequations are expressedas time derivativesand Hil- high amplitudesurface ripples. Measurements indicate that as the ampli- bert transformsof the displacementvariables. Waveforms calculated with tude of excitation of the surface of water is increased the wave number of the time domainevolution equations are shownto agreewith resultsbased the capillarymotion displays a transitionto a broadbandspectrum. The 3322 d. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128thMeeting: Acoustical Society of Amedca 3322 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp temporalresponse of a singlepixel yields the power spectrumof the sampleswith singleand paired driver configurations. Experiments were surfaceheight as a functionof frequency".f." The numerousharmonics conductedin bothdegenerate and nondegenerate planes to studythe effects whichcan be seenat low amplitudemerge at high amplitudeinto a broad- of orthogonalcoupling. Absorption effects of activeand passive drivers are bandspectrum which goes as 1/f 3. This technique should permit the mea- presented,along with asymmetricaldriver configurations. The resultswill surementof turbulentparameters which go beyondthe purportedrange of be used to control and eliminate unwantedtumbling rotationsin the currenttheories. [Work supported by US DOE Divisionof Engineeringand USML-2 DPM experimentsto be flownin 1995.[Work supported by Geophysicsand NASA Microgravity.] NASAthrough JPL Contract No. 958722.] 5:00 5:15 4pPAa16. Experimental study of streaming in acoustic resonators. 4pPAa17. Generation and propagation of high intensity short JosephC. Jankovsky,R. GlynnHolt, and Robert E. Apfel (Dept.of Mech. acousticpulses in dispersivemedia. I. B. Esipov,K. A. Naugol'nykh, Eng.,Yale Univ., New Haven,CT 06520-8286) O. B. Ovchinnikov,A. E. Pashin,and O. M. Zozuly (N. AndreevAcoust. Inst., 117036,Schvemik st. 4, Moscow,Russia) Anomalousrotations of solid and liquid dropshave beenobserved in resonantchambers in both lg and in the microgravityenvironment of Experimentson lasergeneration of acousticalpulses, amplitude 10 spacein the Drop PhysicsModule (DPM) aboardthe UnitedStates Mi- MPa and duration1 /.rs,and their propagationin differentliquids have crogravityLaboratory (USML-1) mission in 1992.The observedtorques beencarried out. Propagation was measured in bothpure liquids and struc- areproduced by acousticstreaming, typically in the nondegenerateplane turedmedia. Nonlinearity and dispersioncaused evolution of the propa- whererotations are undesired,and havebeen attributed to an imbalancein gatingsignals. Some theoretical treatment of theresults indicate the pos- thepaired driver amplitudes. To quantifythe torqueexerted on the inclu- sibilityof obtainingdata on spectralfeatures of thenonlinear response of sion,measurements were madeusing suspended and leviratedspherical the medium. THURSDAY AFTERNOON, 1 DECEMBER 1994 WEDGWOOD ROOM, 1:15 TO 4:45 P.M. Session4pPAb PhysicalAcoustics and StructuralAcoustics and Vibration:Ray Methodsin Radiationand Scattering from Elastic Objects II DouglasA. Rebinsky,Chair Departmentof Mechanicaland Aerospace Engineering, Rutgers University, Piscataway, New Jersey 08855-0909 ContributedPapers 1:15 A raymethod is systematicallyused to derivea relationbetween radi- atedacoustic waves and elastic waves traveling over a smoothelastic shell 4pPAbl. Geometricaltheory of acousticscattering by thin elastic of arbitraryshape. The radiatedacoustic field is foundto be intimately shells. Jin-MengHo (SFA,Inc., 1401McCormick Dr., Landover,MD connectedwith thegeometry of theshell's surface and the elastic wave- 20785and Naval Res. Lab., Washington, DC 20375) fronts.This connectionleads to an asymptoticexpression for the local The soundfield scatteredby a smooththin elasticshell immersed in radiationimpedance associated with eachsurface ray underthe condition fluid ariseslargely from specularreflection and acoustic-membranecou- kfR>•l,where k/is thewave number in fluidand R thesmallest radius of curvatureof the shell.The firstterm in thisformula is actuallythe resultfor pling, unlessboth sourceand observerare locatednear or on the shell. Thesetwo contributionshave been found to be well describedby ray fields an infinitefiat plat,which is homogeneousand isotropic, while the second for canonicalshells in the mid-frequencyregime, and hencemay be gen- termintroduces inhomogeneity and anisotropyinto the radiationimped- eralizedby the principleof localizationto accommodatemore general ancebecause it explicitlydepends on the localcurvatures of the shell's surfaceand the elastic wavefronts. The generalresult is furthersimplified geometries.By examiningthe excitation, propagation, and radiation pro- cessesof thesupersonic membrane waves on theshell, this paper defines for a cylindricalshell with cross sections of arbitraryshape. Comparisons the excitationand radiation coefficients associated with theseshell-guided aremade between the present asymptotic solution and the exact solution in leakywaves as well as thedivergence coefficients of theray tubeschar- thetwo special cases of vibratingcircular cylindrical shells and spherical shells.It tumsout thatthe first two termsin the asymptoticexpansions of acterizingthe variation of thewave amplitudes. It extends the concepts of Kellerand Karal's geometrical theory for surface waves [J. B. Kellerand thesesolutions have exactly the sameexpression. [Work supported by F. C. Karal,Jr., J. Appl. Phys. 31, 1039-1046(1960)]. The explicit evalu- ONRand NRL.] alUnder contract to NavalRes. Lab., Washington, DC 20375 -5000. ationof thesecoefficients, and thereforethe leaky fields,is demonstrated for two classesof shells--cylindricalshells of arbitrarycross section and shellsof revolution---basedon the knowledgeof cylindricaland spherical 1:45 shellprototypes and differential geometry. The reflectedwaves are more straightforwardandthe related coefficients are readily determined. [Work 4pPAb3. Acousticscattering from fluid-loadedelastic shells:A supportedby ONR.] Gaussianbeam approach. YangYang (SFA,Inc., 1401McCormick Dr., Landover,MD 20785), Andrew N. Norris (RutgersUniv., Piscataway,NJ 08855-0909),and LuiseS. Couchman(Naval Res. Lab., 1:30 Washington,DC 20375-5000') 4pPAb2.Radiation from fluid-loadedsmooth elastic shells of Acousticscattering problems from fluid-loaded elastic shells are usu- arbitraryshape. YangYang (SFA,al Inc., 1401McCormick Dr., ally formulatedin termsof surfaceHelmholtz integrals. The numerical Landover, MD 20785) evaluationof theseintegrals is very time consuming,especially at high 3323 J. Acoust. Soc. Am., Vol. 96, No. 5, Pt. 2, November 1994 128th Meeting:Acoustical Society of America 3323 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp frequencies.A newmethod is proposedhem for the computationof the 16802-140l), AkhleshLakhtakia, and RenataS. Engel (PennState scatteredfields. The basicidea is to usemy methodsto first representthe Univ., UniversityPark, PA 16802-1401) supersonicsurface fields. The surfaceintegral is then representedas a Time-dependentStokesinn fluid flow aroundan arbitrarybody can be summationof individualintegrals along Gaussian beams. Each integral is analyzedin termsof time-harmonicphasers. Analytical techniques com- approximatedas a line integralalong the centerray of the beam,and monlyused for frequency-domainscattering can thereforebe broughtto finally,the acoustic far field is obtainedby asymptoticallyevaluating each use.The scatteringresponse of a bodyis oftenquantitated by theextinction line integralat its stationarypoints. The asymptoticexpression for the crosssection. However, the wave number for StokesJanflows is necessar- membranewave part is uniformand valid at all theobservation angles. The ily complex,so the usualinterpretation of the extinctioncross section is difficultiesof dealingwith causticsand infinite sets o[ raysdo not arisein untenablein the presentinstance. It is shown,however, that a detector- the presentformalism. This approachallows the acousticresponse to be basedinterpretation of the extinctioncross section is unambiguousand easily calculatedwithout resortingto two-pointray tracingor surface experimentallyrelevant. An almostexact formula is derived for the ex- Helmholtzintegrals. It is thereforenumerically fast. The numericalresults tinctioncoefficient for the fir-field, forwardscattering case. Computed agreewell with the availableexact solution and the pureray resultson a valuesof extinctioncross sections are presented for spheresand spheroids. sphericalshell for kfa>10,where kf is thefluid wave number. [Work supportedby ONR andNRL.] 2:45-3:00 Break 2:00 3:00 4pPAb4. Impulse response of thin shells: Source development, analysis of the bipolar specular contribution, and computations 4pPAb7. Approximate diffraction coefficients. Paul E. Barbone (Dept. showing the effect of water on the inside of the shell. Gregory of Aerospaceand Mech. Eng., 110 CummingtonSt., BostonUniv., Boston, Kaduchakand Philip L. Marston (Dept.of Phys.,Washington State Univ., MA 02215) Pullman,WA 99164-2814) Expressionsfor diffractioncoefficients for canonicalshapes, joints, and The responseof shellsto a delta functionpressure impulse is well discontinuitiesare necessaryin applicationsof the geometricaltheory of suitedto interpretationwith raymethods. We examinethe theory for PVDF diffractionto scatteringfrom submerged structures. In manycases of prac- sheetsources [C. S. Kwiatkowski,G. Kaduchak,and P. L. Marston,J. tical interest, however, the diffraction coefficientsare either not available Acoust.See. Am. 94, 1831(A) 0993)] which[acilitated wideband impulse or are very difficult to evaluate. The use of perturbationtheory and scatteringmeasurements in modest-sizedwater tanks.Response features matchedasymptotic expansions in obtainingsuitable approximations of for sphericaland nonsphericalshells will be discussed.An approximation diffractioncoefficients is described.These two methodscan yield approxi- is developedfor thebipolar specular feature which for an emptysphere of mationsthat aresimple to compute,easy to apply,and arevalid in comple- radiusa becomes&(T)-2xt• exp(-xNT)O(T ), whereT=tc/a, the delta mentary parametricranges. The perturbationmethod assumesthat the functionis the initial specularecho, 0 is a unit step function,and propertiesof the solidor its geometryare nearlyhomogeneous. Matched x•t= pa/pœhis thedimensionless null frequency.The densitiesof theshell asymptotics,on the other hand, is a useful tool when the solid is nearly andwater are Pe andp. Thusthe mass-per-areapEh for the shellof thick- hard,or the fluid is light. The accuracyof thesemethods is demonstrated nessh affectsthe magnitudeand decaytime of the negativefeature. Ob- by comparingthem to the exactsolution for diffractionby an impedance servationsfor an emptyspherical shell and an end conepiece of an MIT/ discontinuity.When the effortis madeto obtainuniformly valid asymp- NRL model shell will be examined.Computations show that both the totic expressions,the resultsprove to be remarkablyaccurate even at bipolarfeature and the coincidencefrequency wave packetfor spherical valuesof ½=1 (here,• is a "small" parameter). shellsare not quenched when water is insidethe shell. [Work supported by ONR.I 3:15 2:15 4pPAbg. Acousticand flexural wave interaction at the junction of two fluid-loaded plates. Andrew N. Norris, DouglasA. Rebinsky 4pPAbS. Asymptotic determination of the eigenfrequenciesof a (Dept. of Mech. and Acrosp.Eng., RutgersUniv., Piscataway,NJ spherein a fluid. G.C. Gaunaurd(Naval Surface Warfare Center, White 08855-0909), and G. Wickham (Univ. of Manchester,Manchester M13 Oak Detachment,R-34, SilverSpring, MD 20903-5640) 9PL, UK) Startingfrom a phase-matchingprinciple that is tbe acousticalanalog A generalsolution is developedfor theacoustic and structural scattered of the Bohr-Somerfeld-Wilsonquantization rule of the old "quantum responsefrom the junction of two flat platesunder unilateral fluid loading. theory,"it is analyticallyshown how to asymptoticallyobtain the eigen- The platesare modeledby theclassical theory of flexure,and the solution frequenciesof an insonifiedsphere immersed in a fluid.This technique was is foundusing the Wiener-Hopf technique for the dualintegral equations firstillustrated by J. B. Keller[cf. Ann. Phys.4, 180-188 0958)] andit for the unknownpressure on theplates. Explicit formulas are obtained for has been extendedby many authors,notably L. B. Felsenand J. M. He, the pressuretransform when the platesare in weldedor clampedcontact, who have renamedit the "ray-acousticalgorithm." It is shownhere how andcorresponding explicit and relativelysimple expressions are givenfor the acousticalcounterpart of this quantumprinciple leads to a resonance the various diffraclinn coefficients associated with the fluid/structure in- conditionfor the (external)eigenfrequencies of a sphere(rigid, soft,or to teraction.Numerical results for theredistribution of energyfrom flexural to someextent, elastic) that exactlycoincides with F. W. J. Olver's(1954) flexuralplus acousticat a thicknessdiscontinuity will be discussedin classicalasymptotic formula for the(complex) zeros of thespherical Hen- detail.[Work supported by ONR.] kel functions.The polesof thescattering amplitude of an elasticsphere fall into two great families. one dependingon shape.and the other on elagtie composition.The asymptoticspacings in betweenthe shape-dependent 3:30 zerosin the (complex)ka planeare shownto reduceto a uniformvalue, 4pPAb9. Longitudinal wave diffraction generated at curved plate obtained earlier by numerical means, which manifestsitself in all the junctions. DouglasA. Rebinsky (Dept. of Mech. andAerosp. Eng., (RST) "background"curves of the sphere. [Work supportedby RutgersUniv., P.O.Box 909, Piscataway,NJ 08855-0909) NSWC-DDIR Program.] A perturbationsolution is developedto studydiffracted longitudinal 2:30 membranewaves originating from the junction of twocurved plates which arejoined so thattheir tangentis continuous.It is shownthat the diffracted 4pPAb6. Concerning the extinction cross section of an arbitrary longitudinalwave field in the platesis dependentupon or forcedby a body in Stokesianfluid flow. ScottA. Wymer (Dept.Eng. Sci. and backgroundsolution which characterizesthe acousticinteraction between Mech., Penn State Univ., 227 HammondBldg., UniversityPark, PA twojoined, fiat plates and the surrounding fluid. Two forms of background 3324 J. Acoust.Soc. Am., Vol. 96, No.5, Pt,2, November1994 128thMeeting: Acoustical Society of America 3324 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp wavefields are used: (1) a simplesolution based on the acoustic diffraction system.The equivalentforces, which in generalhave both normaland from two massiveplates, and (2) the solutionof acousticdiffraction from tangentialcomponents, are functionsof the shell displacementsat the twoflat plates governed by theclassical theory of flexure.Explicit expres- attachments;the latter may be in turn determinedfrom their continuity sionsare shownfor the longitudinaldiffraction coefficients, associated conditionsand evaluated either by normal-modeseries or the geometrical withthis fluid/structure interaction. The reciprocal problem of anincoming acousticsfields and shell guided modes. [Work supported by ONR.] longitudinalwave to thejoint is discussed.Numerical results of the dif- fractioncoefficient will be shown.[Work supported by ONR.] 4:15 3:45 4pPAb12.Structural and acousticresponses of mass-springloaded elastic cylindrical shells: Numerical implementation. Jin-Meng Ho 4pPAb10. Retroreflective backscattering of ultrasound due to (SFA, Inc., 1401 McCormick Dr., Landover, MD 20785 and Naval Res. Rayleigh waves on an elastic solid rectangular parallelepiped. Lab., Washington,DC 20375) KarenGipson and Philip L. Marston (Dept.of Phys.,Washington State Univ., Pullman,WA 99164-2814) An importantstep in dealingwith the mass-springloaded cylindrical shell is to evaluatethe total shell displacementsat the attachmentpoints, High-frequency(1.5-MHz) sonarexperiments were performedon a whichdetermine the strengthof theequivalent forces. Through dynamical solid stainless-steelrectangular parallelepiped block in water in order to balanceat suchpoints, these displacements satisfy a systemof linearequa- determinethe mostlikely mechanismfor producinga stronglybackscat- tionswhose coefficients involve the shell displacementsgenerated by on- teredsignal. When the angle of incidenceis nearthe Rayleigh angle of the surfaceforces of unit strength,a Green's-functionproblem with both steel,a leaky Rayleighwave is launchedon the flat surfaceof the block. source and observer located on the shell surface. It is thus evident that When this wave reachesthe edgeof the block, part of it is reflectedand flexuralwaves, though subsonic, must be accountedfor in the ray acoustic propagatesto the adjacentedge forming the comer,where it is reflected solutionto thelatter problem. Numerical examples show that they produce again. The net result is that the wave vector of the Rayleigh wave is high Q intenseresonances because of their extremely small radiation reversed,and the resultingleaky radiationgives a pronouncedenhance- damping,which would be dominatedby structuraldamping for dissipative ment of the backscattering.For a randomlyoriented block, this effect is shellmaterial, imprinting their signature in the far field throughradiation morelikely to be observedthan specular reflection, since the latter requires of the inducedforces and carrying much of theinformation on the internal that two of the Euler anglesof the surfacenormal lie in a small range, load.By includingthe flexuralas well as membranewaves, the ray model whilefor theRayleigh mechanism only oneangle is narrowlyconstrained. accuratelypredicts the inducedforces, the shell displacements,and the The observedpeak amplitudeof the retroreflectedbackscattered signal surface and far-zone pressuresin the frequencyrange of interest; agreeswell with an approximatetheoretical model [Marston et al., J. l• 3325 J. Acoust. Soc. Am., Vol. 96, No. 5, Pt. 2, November 1994 128th Meeting:Acoustical Society of America 3325 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp THURSDAY AFTERNOON, 1 DECEMBER 1994 TRINITY A AND B, 1:30 TO 4:35 P.M. Session4pSP SpeechCommunication: Speech Gestures JosephS. Perkell,Chair MassachusettsInstitute of Technology,Room 36-591, 50 VassarStreet, Cambridge, Massachusetts 02139-9992 Chair's Introduction--l:30 ContributedPapers 1:35 Turk, MelanieMatthies, Joseph Perkell, and Mario Svirsky (,Res.Lab. of Electron.,Rm. 36-531,MIT, Cambridge,MA 02139) 4pSP1. Evidenceof gesturaloverlap acrossspeaking rate: Acoustic data. Kris Tjadenand Gary Weisruer (WaismanCtr. and Dept. of The purposeof this studyis to determinewhether intrinsic vowel Commun.Disorders, 1500 HighlandAve., Univ. of Wisconsin Madison, durationdifferences arise from an explicit timing control strategy or solely Madison,WI 53705) from thedistance an articulatortravels. Presumably, a difference in control strategywould be reflectedin a changein the relationof peakvelocity to The form of phoneticgestures has been assumedto remainstable distancetraveled, or in the amountof time positionis maintained.An acrossvariations in speakingrate. Segmentalization or amountof gestural EMMA systemwas usedto track movementsof pointson the tongueand overlaphas been shown to covarywith speakingrate. However, the precise jaw duringthe production of/dVs/(V=/e, E, •e, a, M) tokensin a constant relationshipbetween speaking rate and acousticmeasures of segmental- frame at two differentspeaking rates. Measurements were madeof target izationhas not beendelineated. In the presentinvestigation, speakers pro- position,distance traveled, and peak velocityfor eachgesture toward and ducedmultiple repetitionsof the words "build," "dill," and "gill" in away from the vowel target.Preliminary results from one speakersuggest carrierphrases at graded,self-selected speaking rates ranging from slow to that the durationof articulatorymovement can be well predictedby ar- fast. F2 onsetfrequency of the vocalic nucleusserved as an index of ticulatorydistance and peakvelocity alone. Furthermore, all of the unre- scgmentalizafionand was usedto predictthe time delayto theonset of the ducedvowels measured in the studyshowed a similarrelationship between majorF2 transitionassociated with/IlL Previouswork suggestsF2 onset peak velocityand displacement,suggesting that the samecontrol strategy frequencyis sensitiveto degreeof gesturaloverlap in vocalicnuclei pre- wasused for all of them.[Work supported by NIH.] cededby alveolarconsonants. Preliminary results suggest (1) longer calic nuclei tend to be associatedwith F2 onsetfrequencies closer to the precedingconsonantal articulatory locus, and (2) the linear relationship 2:20 betweenF2 onsetand time to targetdeteriorates above certain speaking 4pSP4. On the perceptual characteristicsof "speech gestures." durations,suggesting that the basic form of thegesture is alteredat slower Ren6 Cart6, Samir Chennoukh (ENST, 46 rue Barfault, Paris, France), rates.[Work supported by DC 00319.] PierreDivenyi (VeteransAffairs Med. Ctr., Martinez,CA), and Bj6rn Lindblom (Univ. of Stockholm) 1:50 The notionof "speechgesture" or "phoneticgesture" has been devel- 4pSP2.Articulatory evidencefor acousticgoals for consonants.J.S. oped as a theoreticalconstruct during the past few years.For present Perkell,M. L. Matthies,and J. A. Svirsky (,SpeechCommun. Group, Res. purposes,the term is specifiedas a "phonologicallysignificant task defined Lab. of Electron.,Rm. 36-511,MIT, Cambridge,MA 02139) on the vocal tract area function."A given task generallyinvolves the coordinationof the movementsof severalarticulators. It appearsreason- Evidencehas been found for tradingrelations between tongue-body able to expectspeech gestures to have4•eraeptua! raisingand upper lip protrusion(measured with an EMMA system)for the following:(a) Within certainlimits, the time courseof speechgestures is vowel ]u], reflectinga "motor equivalence"strategy that shouldhelp to notimportant; (b) withincertain limits, the precise synchronization of two, constrainacoustic variation [Perkell et al., J. Acoust.Soc. Am. 93, 2948- or more,gestures (e.g., constriction displacement and lip opening)is also 2961 (1993)].Theoretically, analogous relations in the transformationbe- unimportant;(c) vowelreduction is a naturalconsequence of speechges- tween the area functionand the acoustictransfer function are possiblefor ture characteristics.The commandsof the distinctiveregion model were the consonants/r/and/J'/,which are alsoproduced with two independently studiedas possiblespeech gestures. Preliminary tests show, as hypoth- controllableconstrictions, formed by the tongueand by the lips. Such esized,that there are no significantperceptual differences (a) when the relationsmight occur more among tokens that are leastprototypical, i.e., shapeof a gesturaltransition is changedto be linear,quadratic, logarith- closestto perceptualboundaries. In a preliminarytest of thesehypotheses, mic, or cosine;(b) whenthe time separationbetween two gesturesvaries a singlespeaker has producedthe sounds/r/,/•/, and /u/, embeddedin from -30 to +30 ms;(c) whengesturai dynamics (transitional rate of contextsthat mightinduce differences in prototypicality.Motor equiva- change)is keptconstant but the target is notreached (because of move- lencewas observedfor the ]u/ in /rut/ (leastprototypical, with the highest ment undershoot). F2 values)but not in/pub/or/hudL For/r[ and[•/, anteriordisplacement of the tongueconstriction was positively correlated with upperlip protru- sion,providing initial supportfor the hypothesisthat movemenlgoals for 2:35 the consonantsalso include acoustic components, which are manifestedin 4pSP5. The articulatory kinematics of two levels of stresscontrast. a tendency to maintain sufficient front cavity length to help assure K. BretonnelCohen, Mary E. Beckman (Linguist.Dept., Ohio State acoustic-phoneticdistinctivehess. [Work supported by NIDCD.] Univ., Columbus,OH 43210-1298), Jan Edwards,and Marlos Fourakis (Ohio StateUniv.) 2:05 Intonationpattern and syllableduration are thoughtto be the most 4pSP3. On explaining intrinsic vowel duration differences: An salient perceptualcues to phrasestress. However, intonationis an inher- electromagnetic midsagittal articulometer (EMMA) study. Alice ently ambiguouscue, sincenot all Englishpitch accentsinvolve higher 3326 J. Acoust.Soc. Am., VoL96, No. 5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3326 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp pitchon the accentedsyllable, and becausethere are stresscontrasts at a 3:35 lowerlevel, where stress cannot be equatedwith accentuation.Duration, too,is ambiguous, since it cancue other prosodic contrasts, such as phrasal 4pSP8.Control of lip closurein stopconsonant production. An&rs position.This study examines finer-grained timing cues to stress.A strain- L6fqvistand Vincent L. Gracco (HaskinsLabs., 270 CrownSt., New Haven, CT 06511-6695) gaugesystem was used to examinejaw openingand closing movements in /pop/sequencesin intonationallyaccented full-voweled syllables, unac- Studiesapplying mechanical perturbations to thelower lip andthe jaw centedfull-voweled syllables, and completelystressless (reduced-vowel) haveshown a tradeoff betweenmovements of perturbedand unperturbed syllablesproduced by fore speakers.Measured values for movementdu- articulatorsin makingthe lip closurefor a bilabialstop. While thisconcept ration,displacement, and velocity were consistently larger in accentedthan is attractive,evidence for suchtrading relationships in normalspeech has in unaccentedfull-voweled syllables. However, these differences were no- remainedelusive, partly due to methodologicalproblems. This studyex- where near as large as the differencesbetween full- and reduced-vowel aminesthe vertical positionsof the upper and lower lip at closurefor syllables.Reduced syllables also had steepervelocity-displacement rela- bilabialstops. An electromagnetictransduction system was usedto track tionships,suggesting a durationaldifference at the level of gesturaldy- receiverson the upperand lower lips, and the lower incisorsfor transduc- namics as well. However, no such consistent difference was observed ing jaw movements.The speechmaterial consisted of VCV sequences betweenaccented and unaccentedfull-voweled syllables. These results wherethe firstvowel was/a/, the middleconsonant/p,b/, and the second supportthe notion that stress contrasts are notuniformly interpreted in the vowel/i,a/; stressoccurred on the secondvowel. Preliminaryresults from phoneticsat differentlevels. threesubjects showed upper lip positionsat closureto occurover a range of 0.3 cm; the rangefor lower lip positionswas 0.5 cm. Examinationof 40 tokensfor eachsubject revealed a positiverelationship between upper and lower lip positionsat closure,with correlationcoefficients ranging from 2:50-3:05 Break 0.5 to 0.7. The resultswill be discussedin relationto theoriesof speech motorcontrol. [Work supported by NIH.] 3:05 3:50 4pSP6. The IPA problem. Peter Ladefoged (Phonet.Lab., Linguist. 4pSP9. Exploring the relationship of breath intake to utterance Dept., UCLA, Los Angeles,CA 90024-1543) duration, D. H. Whalen and J. M. Kinsella-Shaw (HaskinsLabs., 270 Crown St., New Haven, CT 06511) Every few years it is appropriateto review our knowledgeof the Previouswork hasindicated that theremay be a positiverelationship phoneticstructures of the world's languagesand try to assesshow many betweenthe duration and extent of breath intake and the length of an differentspeech sounds there are. Problemsarise because it is not easy to upcomingutterance. However, none of that work hasbeen free of alterna- say whethertwo soundsoccurring in differentlanguages are the sameor tive interpretations.An attemptwas made to avoid someof thoseby forc- not. Two soundsare definitelydifferent if they distinguishwords within a ing subjectsto utter singlesentences ranging in lengthfrom 5 to 82 syl- language.But if theyoccur in differentlanguages this testcannot be used. lables(mean of 27), after inspiringfully andthen expiring down to a set This is the basisof the IPA problem.The InternationalPhonetic Associa- level beforeuttering the sentence.For threesubjects, there was a signifi- tiontries to providea way of symbolizingevery distinct speech sound, but cantpositive relationship between breath intake and utterance length (0.65, it cannottell whethertwo soundsare potentiallydistinct when they have 0.50, and 0.29 individually).This was still true withoutthose utterances beenobserved only in differentlanguages. The datafrom recentphonetic containinga secondary breath (0.53, 0.54, and 0.29). The two subjects with studiesindicate that thereare limitlessways in which the soundsof one the highercorrelations also exhaled more quickly for the shortersentences languagecan differ from another, but that the numberof parametersalong thanlonger ones. The other subject had no correlation with exhalation rate: whichsounds can vary is fairly small.In mostcases the variationin the He mighthave been selecting a pointwithin a ratherlarge range of starting soundsthat occurin differentlanguages is the resultof the useof a dif- lung volumes,with only the longestsentences requiring that the range's ferentvalue of one of the parameters,rather than the use of somenovel lowerpart be avoided.The individualdifferences need further investiga- parameterthat hasnot beenobserved in other languages. tion, but there is a correlation between the duration of the sentenceto be said and the breathbefore it. [Work supportedby NIH Grant No. HD- 01994.] 3:20 4pSP7.High voweldevoicing in Turkish. StefanieJannedy (Dept. of 4:05 Linguist.,Ohio StateUniv., 222 Oxley Hall, 1712 Nell Ave., Columbus, OH 43210) 4pSPI0. An analysisof the variationof vocaltract configurationsin continuousspeech utterances. TokihikoKaburagi and MasaakiHonda (Information Sci. Res. Lab., NT]7 Basic Research Laboratories, 3-1, Junand Beckman(ICSLP94) explainvowel devoicingin Japaneseand Morinosato-Wakamiya,Atsugi-shi, Kanagawa, 243-01 Japan) Koreanin termsof gesturaloverlap [Browman and Goldstein, LabPhonl (1990)];the glottal gestures for precedingand following voiceless conso- This paperstudies the variation of voweland consonant articulation to nantsoverlap to a greateror lesserextent with theglottal gesture for high examinethe invariantfeatures of phoneme-specificvocal tract configura- vowels.The devoicingof the four shorthigh Turkish [i i y u] can be tions.The establishmentof thesefeatures may be one of the goalsof explainedby the samemodel which predicts that vowels are morelikely to organizingarticulatory movements, and they can be usefulin constructing undergodevoicing if theyare shortand the adjacentvoiceless consonants modelsof thosemovements. Articulatory data were gatheredwith a mag- havestrong and large glottal opening gestures. This studyevaluates influ- netic position-sensingdevice that tracedthe positionof receivercoils encingfactors such as preceding and following environment, rate, stress, placedon thelower jaw, upperlip, lowerlip, andtongue in themidsagittal andsyllable type. Subjects read 210 wordspositioned utterance initially in plane.Experiments were performed using (a) V•V0_V3,(b) V•V2V3V,,V5, a carrierphrase at threerates. Faster rates and lack of stressfacilitated (c) V•CV 2, and(d) CV1CV2CV3CV4CV5 contexts, where V i wasa com- devoicingmost. As in Japaneseand Korean,there were moredevoiced binationof vowels/a,i,u,e,o/andC was one of consonants/p,t,k,b,d,g/.A vowelsbefore following stops than before following fricatives, since vocal Japanesemale subject uttered these sequences at severalspeeds with dif- fold vibration ceasesgradually before fricatives, but abruptly before stops. ferent stress. Articulatory data were sampled when the vocal tract con- Devoicingalso occurred in utterance-initialposition. This resultis less strictedfor vowels or when the vocal tract closedfor plosiveconsonants: easyto interpretin termsof the model,since only the followinglaryngeal For eachvowel and consonant,200 data frameswere sampledon average gesturecan overlapwith the vocalicgesture. More devoicingoccurred in from the whole data set of about150 000 frames(10 rain). The variability opensyllables, where vowels are significantlyshorter in Turkish. of the vocal tractconfiguration was then quantitativelyanalyzed for each 3327 d. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128th Meeting:Acoustical Society of America 3327 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp phonemeby calculatingthe variation of eachmeasurement point from its A methodinvolving task dynamicsand a geneticalgorithm [see averageposition. The variationwas very smallwhen the vocal tract closed McGowan,Speech Commun. 14, 19-48 (1994}]was usedto recoverar- or constricted,especially in the traversaldirection. How phonemecontent, ticulationfrom the speechacoustics of a humansubject. Six utterances utterancespeed, and stressaffect the vocal tract configurationwas also from a singlesubject were chosen to testthe applicabilityof the proposed investigated. methodto humanbeings:/gad,/gi/,/dad,/di/,/bad, and foil The firstthree formanttrajectories of the naturalutterances were extractedand usedto 4:20 representthe acousticdata. A geneticalgorithm was usedin constrained optimizationof task-dynamicparameters applied to the HaskinsLabora- 4pSPII. Perceptualevaluation of articulatory movementrecovered toriesarticulatory synthesizer, ASY. The articulatorymovements recovered from acousticdata. RichardS. McGowanand Philip E. Rubin (Haskins in thismanner were assessed using perceptual tests of theresulting speech Labs.,270 CrownSt., New Haven,CT 06511-6695) generatedby ASY andby a visualizationof theresulting ASY articulation. THURSDAY AFTERNOON, 1 DECEMBER 1994 BALLROOM B, 1:00 TO 5:00 P.M. Session4pUW Underwater Acoustics:Bottom Scattering Charles Loeffier, Chair AppliedResearch Laboratories, University of Texas,P.O. Box $029, Austin, Texas78713-8029 ContributedPapers 1:00 Corpsof EngineersWaterways Experiment Station (CEWES) HPC Center, Vicksburg,MS.] 4pUWl. Bistatic bottom scattering observed by seafloor vertical arrays during the July 1993 ARSRP bottom reverberation experiment. K. B. Smithand W. S. Hodgkiss(Marine Phys. Lab., 1:30 ScrippsInst. of Oceanogr.,La Jolla,CA 92093-0704) 4pUW3. Simulations of the 1993 ARSRP deep ocean seafloor scattering experiments using rt•VEST--An adaptive wave During the July 1993 ARSRP bottomreverberation experiment, the propagation regime simulation technique. Johan O. A. Robertsson, R/V K•ORR deployedbottom-moored, 64-element, vertical line arrays AlanLevander (Dept. of Geol.and Geophys., Rice Univ., P.O. Box 1892, (VLAs) with the data beingrecorded by autonomousdigital recording packages(GARRPs). Bistatic scattering data were recorded by theseVLAs Houston,TX 77251-1892),and Klaus.Holliger (Inst. of Geophys. CH-8093 Zfirich, Switzerland) from R/V CoRYCHOUEST and R./V ALLrAnCEtransmissions. In this paper, bottomscattering observed at Site B' in the SRP NaturalLaboratory with A new generalhybrid technique, HARVEST (hybridadaptive regime these VLAs will be shown and the received scatter related to the source- viscoelasticsimulation technique), to solvethe 2-D acousticdviscoelastic arraypositions and bathymetry. Modeling using UMPE/PEREV [IC B. equationsfor problemswhich encompass different wave propagation re- Smith,F. D. Tappert,and W. S. Hodgkiss,J. Acoust.So;:. Am. 94, 1766(A) gimes,such as the relativelysmooth water column and the highlyhetero- (1993)]and BB-UMPE [K. B. Smithand W. S. Hodgkiss,J. Acoust.Soc. gencousseafloor in deepocean seafloor scattering experiments, is pre- Am. 95, 2826 (A) (1994)]will be usedto provideinsight into the spatial sented.A Gaussianbeam method is usedto propagatethe sourcefield andtemporal structure of the observedscatter. [Work supported by ONR througha verticallyheterogeneous water column to the scatteringregion Code3210A.] nearthe seafloor.This extrapolatedsource field is insertedinto a viscoelas- tic finite-differencemethod used to computethe complexacoustic/ 1:15 anelasticinteraction of the wavefield with the roughseafloor. The back- scatteredfield is extrapolatedto a receiverarray distant from the scattering 4pUW2. Computer model simulations of reverberation from the localeby meansof the Klrchhoffintegral. HARVEST is employedto ARSRP acousticsexperiment. StanleyA. Chin-Bing (NavalRes. Lab., simulateocean acoustic reverberation data collected during the 1993AR- StennisSpace Center, MS 39529-5004)and JosephE. Murphy (Univ.of SRP (AcousticReverberation Special ResearchProgram) Acoustics New Orleans,New Orleans,LA 70148) Cruise.HARVEST is foundto successfullyreproduce ocean acoustic data Detailed reverberation measurements were made from the mid-Atlantic withinthe confidence limits imposed by knowledgeof seafloormorphol- ogyand material properties. The nature of scatteringtargets is interpreted ridgeregion during the 1993Acoustics Experiment, Acoustic Reverbera- from acousticsdata in termsof syntheticHARVEST simulated data. In tionSpecial Research Program (ARSRP). The reverberationscenario (des- particular,rough basement that 0arely protrudes the sedimentcover may ignatedas "Seg 076") that ensonified a segment of sedimentedseafloor causestrong returns in the backscatteredfield. overlying an anelasticsubbottom has been examined.Computer simula- tionsof the reverberantfield wcrc generatedand comparedwith the AR- SRP measuredreverberation. Time domainand cw computersimulations 1:45 were made usinghigh-resolution ocean acoustic-seismoacoustic computer 4pUW4. Shallow-wateracoustic experiment in the Strait of Sicily models.Several realizations of the rough range-dependentsediment and Area: Preliminary resulls. J. M. Berkson (Naval Res. Lab., sub-bottomwere used(from the Webb-Jordansediment distribution model Washington,DC 20375), A. Kristensen,M. Max (SACLANT Undersea and the Goff-$ordanfraetel seafloor/basement model). Computer simula- ResearchCtr., 19138 LaSpezia, Italy), T. W. Yates, and G. M. tionsallowed "numerical expertmeres" to be performedwhereby parts of Vetmillion (VectorRes., Rockville, MD 20852) theenvironment were changed or eliminated.Simulation results that help identifythose seafloor regions responsible for the reverberantreturns are Shallow-wateracoustic and geoacousfic measurements were madein presented.[Work supported by ONR,Acoustic Reverberation SRP, and the thesouthwest margin of theAdventure Bank area of theStrait of Sicilyin High PerformanceComputing DoD SharedResource Center: U.S. Army a regionhaving about 120-m water depth and a generallysmooth calcar- 3328 J. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3328 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp eoussand seafloor. Concurrent propagation and reverberation experiments with 5-mssignal length, and 10-sinterval. The shipmade a hexagonalrun were conductedusing horizontal and verticalarray receivers with both with the horizontalreceiver array insidethe track.A theoreticalsource broadbandexplosive and controlled narrow-band sources. Propagation is modelhas been designed to approximatethe actualsource pulse, and is frequencydependent with minimumtransmission loss at long rangeoc- usedto match-filterthe data.The modalarrivals are clearly identified in the curringin thefrequency band 200-800 Hz. Overallreverberation envelope resultingimpulse responses, allowing for mode-by-modeanalysis. The of duration was about 60 s and includes both diffuse returns and arrivals totalfield is decomposedinto a meanfield (coherentfield) andscattered frommajor bathymetric features. [Work supported by ONR.] field (incoherentfield) by a stackingprocedure. The spatialcoherence is thencalculated using a correlationand a coherencefunction. The magni- tudesquare of thecomplex coherence function (MSC) of thetotal field was 2:00 0.9 while the MSC of the scatteredfield was 0.1, whichsuggested that the 4pUW5. Acoustic wave scattering by 3D variability of deep ocean bottomroughness was very small,allowing for modelingby perturbation sediments.D. Tang,D. Li, G. V. Frisk,and C. J. Sellers (Dept.of Appl. theory. OceanPhys. and Eng., WoodsHole Occanogr.Inst., WoodsHole, MA 02543) 2:45 Volumetricinhomogeneities of marinesediments, especially their hori- 4pUW8. Scattering due to sound-speedinhomogeneities in ocean zontalchanges, are of great importancein understandingbottom scattering waveguides. BrianTracey and Henrik Schmidt (Dept. of OceanEng., processes,but difficult to assess.Though certain theoreticalmodels are MIT, 77 MassachusettsAve., Bldg. 5-007, Cambridge,MA 02139) available,so far little is known aboutsediment variability experimentally. During the 1993 ARSRP experiment,bottom scattering data over a sedi- A self-consistentperturbation method for three-dimensionalacoustic ment pond were obtainedusing the Deep Towed Acoustics/Geophysics scatteringdue to sound-speedinhomogeneities has beendeveloped. This System(DTAGS) nearthe bottomwith its receivingacoustic array con- methodallows calculationof the mean-fieldattenuation due to scattering, figured vertically. By analyzingthis data set, the following resultshave as well as the second-orderstatistics of the reverberantfield. Propagation beenfound: (1) The sedimentis layered,but with gentlechanges horizon- in a shallowocean overlying a sedimentbottom containing sound-speed tally.(2) Beamformingin the normaldirection of multiplepings reveals inhomogeneitiesis consideredas an application.A modalexpansion of the that there are two irregularsublayers at depthsof about 16 and 60 m acousticfield is assumedand (mean-field) modal attenuationcoefficients beneaththe seafloor.Their thicknessesare bothabout 15-20 m. (3) Simu- are calculated.The attenuationcoefficient calculation is straightforward lationsbased on a simplemodel compare favorably with the experimental and is suitable for use with standard normal-mode codes. Numerical results data,and the resultssuggest that volumetricinhomogeneities can be iden- showthis work is consistentwith an earlierapproach to plane-wavescat- tified by examiningthe ping-to-pingcorrelation of the verticallyreflected tering[D. Tangand G. Frisk,J. Acoust. Soc. Am. 90, 2751-2756(1991)], field. (4) The backscatteredfield is determinedby first subtractingthe and illustratethe importanceof scatteringinto the continuousspectrum. coherentlyreflected portion of the field andthen beamforming the residual The spatial correlationand intensity of the reverberantfield in the portionat the desiredgrazing angles;the behaviorof the backscattered waveguideare calculated.[Work supported by ONR High LatitudePro- field correlateswell with the aforementionedirregular sublayers. [Work gram.] supportedby ONR.] 3:00-3:15 Break 2:15 3:15 4pUW6. Backscatteringdata analysis using multiple constraint beamforming. D. Li, D. Tang,and G. V. Frisk (Dept. of Appl. Ocean 4pUW9. Bistatic reverberation from an ocean ridge. Nicholas C. Phys.and Eng.,Woods Hole Oceanogr.Inst., Woods Hole, MA 02543) Makris, Lilimar Avelino, and Richard Menis (Naval Res. Lab., Washington,DC 20375) Using a vertical receivingarray to measurebottom backscatteringis clearlyadvantageous over the singlereceiver configuration. In the single Bistaticreverberation from a highly lineatedridge in the mid-Atlantic receivercase, one uses arrival time informationand the assumptionthat the was measuredby two researchvessels during the ARSRP Main Acoustics scatterersare on the seafloorto obtainbackscattering strength as a function Experimentof 1993. Eachvessel used a verticalsource array and a hori- of grazingangle; a vertical array,on the other hand, can be steeredin zontalreceiving array to collectbistatic and monostaticdata over a full variousdesired directions without invokingthe aforementionedassump- rangeof incidentand scattered angles with respectto theridge axis. High- tion. However, sediment stratification causesreflections in the normal di- resolutionbathymetry reveals that the ridge protrudesabove conjugate rection,which are generallymuch stronger than the scatteredsignals at depthfor roughly50 kin, and is characterizedby a numberof extended obliqueangles. If oneuses conventional beamforming, the reflected signals scarpsrunning parallel to the ridge axis. Sufficientexcess depth exists in the normaldirection may thereforecontaminate the signalsreceived at aroundthe ridgeto isolateit with waterbornepropagation paths from 1/2 obliqueangles through sidelobe leakage. Therefore a multipleconstraint convergencezone (CZ) range(•33 km) wherelow-frequency returns reg- beamformingtechnique is appliedwhich substantially reduces the sidelobe ister preciselywith steepscarps. Significant variations in receivedlevel level in the normal directionand enablesone to measurebackscattering froma givenscarp occur as a functionof incidentand scattered angle. The strengthat obliqueangles. This techniqueis employedin the analysisof a most prominentreturns register with scarpsfacing the receivingarray. deepocean backscattering data set,and it is foundthat sedimentinhomo- Registrationbetween returns from high-resolution waveforms (-10 m in gertcitiesrather than seafloor roughness are theprimary cause of backscat- range)and fine-scale bathymetry is usedto elucidatethe fundamental scat- tering.[Work supported by ONR.] teringprocess. Comparisons with monostaticmeasurements of the same ridgefrom 1/2 CZ and 2 1/2 CZ indicatehow fine-scalestructure from a 2:30 givenscarp is smearedin long-rangereverberation. 4pUW7. Spatial coherenceand rough bottom scattering in shallow 3:30 water. R. Dwi Susantoand Henrik Schmidt (Dept.of OceanEng., MIT, Cambridge,MA 02139) 4pUWI0. Acousticreverberation from a laboratorymodel of a shelf break. SaimuLi andC. S. Clay (Geophys.and Polar Res. Ctr., Univ.of Shallow-water acoustic data collected off Mallorca in March 1993 are Wisconsin-Madison,1215 W. DaytonSt., Madison,WI 53706) analyzedfor spatialcoherence, and their relationto rough bottomscatter- ing is investigated.Bistatic reverberation data were collectedby a hori- The structure of continental boundaries such as the east coast of the zontalreceiver array with equispacedhydrophones suspended 1 m above UnitedStates has a shallowsloping bottom that changes to a steeperslope the bottom.A flextentionaltransducer towed behind the ship was usedas at the shelf break.Our laboratoryacoustic model has exaggerated slopes. a source,generating a 209-dBsource level at centerfrequency of 400 Hz, The "shelf" hasa 10.8ø slope;the bottomchanges to a 50ø slopeat the 3329 d. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128th Meeting:Acoustical Society of America 3329 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp shelfbreak. The surfaceand bottomof the acousticmodel are drywall Theseabed dominates the shallow-water acoustics problem, but bottom constructionboard. The sourceis a sparkand the receiveris a small propertiesand bottom scattering mechanism are usuallypoorly known. microphone(2 minx2 mm).The Biot-Tolstoyexact time domain solution Detailedinterference paRems in shallowwater are thus not always physi- wasused as a basisfor numericalcalculations [l. Tolstoyand C. S. Clay, callymeaningful for engineeringapplications. A simple analytical expres- OceanAcoustics (American Institute of Physics,New York, 1987), Appen- sionaveraged over frequency or spacecan sometimes give better insight dix 5]. Arrivalsare reflected paths, diffractions from the shelf break, and into somephysical problems. In thispresentation, an averageangular reflecteddiffractions. The existenceand amplitudes of arrivalsdepended powerspectrum method for calculatingshallow-water sound propagation, on sourceand receiverlocations. For example,a sourcelocation in the reverberation,noise, and spatialcoherence is briefly introduced.The innershelf gave reverberations that were mainly from the 10.8ø wedge.A methodis basedon normal-modeand ray-mode analogies and originally sourceposition beyond the shelf break gave reverberationsthat were appearedin Chinesepapers which are not available in English[Zhou, Acta mainlyfrom the 50ø partof the model.Experimental signals matched the Acoust.Sin. 5, 86-99 (1980);Acta Ocean. Sin. 1, 212-217 (1979)].Tak- theory in amplitudesand arrival times. ing activesonar performance prediction as an example,analytical expres- sionsfor range/depthdependences of the soundpropagation, average re- 3:45 verberationintensity, and echo-reverberation ratio will be givenfor several typicalcases, including Pekeris shallow water, wedged continental shelf, 4pUWlI. Underwater acousticmeasurements with a digital ocean andnegative gradient waveguide. [Work supported by ONR.] bottom seismometer. David M. F. Chapman,John C. Osler, W. Cary Risley (DefenceRes. Establishment Atlantic, P.O. Box 1012, Dartmouth, 4:30 NS B2Y 3Z7, Canada),and D. JacksonDodds (GeoAcoust.,Inc., Aurora, ON LAG 4J9, Canada) 4pUW14. Averageacoustic field in shallowwater II: Reverberation andits inverseproblem. Ji-XunZhou and Xue-Zhen Zhang (Schoolof A digitalocean bottom seismometer (OBS) hasbeen constructed com- Mech. Eng., GeorgiaInst. of Technol.,Atlanta, GA 30332 and Inst. of prisinga hydrophone,three 4.5-Hz geophonesin a symmetricorthogonal Acoust.,Academia Sinica, Beijing, People's Republic of China) configuration,24-bit sigma-deltaanalogue-to-digital conversion, and a radiotelemetry link to a ship-boardmonitoring and recording laboratory. Averagereverberation intensity and the verticalcorrelation coefficient Carefulattention to self-noisefloors and OBS/seabed coupling has resulted for reverberation,obtained from Pekeris shallow water, are offered as in an instrumentcapable of accuratelymeasuring ambient noise on both possiblesimple test casesfor numericalmodeling of reverberationand hydrophoneand geophonesensors in the 1-50-Hz range.A vibrator bottomscattering mechanism analysis. Measurements were conductedat mountedin the OBS, controllablefrom the receivingplatform, allows in three different areas in the Yellow Sea and the East China Sea with water situ calibrationof the OBS responseto seabedmotion. The instrument's depthsof 40, 29, and 52 m. Thesethree locations have very different design,construction, deployment, and operation will be describedbriefly, seabedsediments, with meangrain diameters of 0.35, 0.07, and0.02 mm, followedby someexamples of the unusualambient noise data setsthat andporosities of 35.5%,46.2%, and 56.1%, respectively. Wideband ex- havebeen collected. At onethinly sedimented site, a very-low-frequency plosivesources with 1000-gTNT chargeswere usedto get 1/3-octave banded structure was observed in the ambient noise on the horizontal reverberationdata with centerfrequencies ranging from 200 to 5000 Hz. geophonechannels only; at many sites,a strong6-I-Iz signalassociated Usingtheoretical results obtained from the angular spectrum method, both with offshoredrilling activity was observedintermittently in all the geo- small-anglebottom reflectivity and scatteringstrength are derivedfrom phonesignals but was not seenin the hydrophonesignals. high reverberation-noiseratio data,including reverberation intensity and verticalcoherence in shallowwater. [Work supported by ONR andIAAS.] 4:00 4:45 4pUW12. Backscatteringin shallow-waterwaveguides caused by obstacleson the seafloor. Finn B. Jensen (SACLANT UnderseaRes. 4pUW15. Scattering of seismicinterface waves from pointlike Ctr., 1-19138La Spezia,Italy) obstaclesin unconsolidatedsediments. Eric Smith, Anthony ArchIcy, JohnA. Behrens,Preston S. Wilson,Benjamin T. Wolz,and Thomas G. As a resultof a recentworkshop on low-frequencyreverberation and Muir (Appl.Res. Labs., Univ. of Texasat Austin, P.O. Box 8029, Austin, scatteringmodeling organized by S. A. Chin-Bingand D. B. King at TX 78713-8029) NRL-SSC, it became evident that accurate wave-theoretic models are availablefor studyingfeature backscattering in oceanwaveguides. A well The conceptof an active,bistatic, seismoacoustic interface-wave sonar tested,two-way coupled mode code [R. B. Evans,J. Acoust.Soc. Am. 74, is investigatedtheoretically and experimentally. The goal of thetheory is to 188-195 (1983)]is appliedto computebackscattering from a singleob- relate the scatteringof seismoacousticinterface waves from materialin- stacleon the seafloor. Of particularinterest is theeffect of heightand slope homogeneitiesand objectsburied beneath an interfaceto their target of the scatteringfacet on the reverberantfield. It is shownthat only steep strengths.This is donein a multipolescattering expansion, which takes a slopescause strong backscattering. simple and efficient form in the limit that the inclusionscan be treatedas pointlikeperturbations of the properties of themedium. Experiments were performedin a sandybeach area of the Gulf of Mexico to demonstratethe 4:15 concept.The experimentsincluded methods for the selectiveexcitation of interfacewaves, and examined the propagation of seismicinterface waves 4pUW13. Average acousticfield in shallow water I: Active sonar in unconsolidatedwet sand, both water-saturatedand unsaturated.The performanceprediction. Ji-Xun Zhou, Xue-ZhenZhang, Peter H. boundaryconditions and target strengths of a collectionof buriedobjects Rogers,and Gary W. Caille (Schoolof Mech. Eng., GeorgiaInst. of were measured,using a varietyof pulse-echoand continuous-wave sonar Technol., Atlanta, GA 30332) configurations. 3330 J.Acoust. Soc. Am., Vol. 96, No.5, Pt.2, November1994 128thMeeting: Acoustical Society of America 3330 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp THURSDAY AFTERNOON, I DECEMBER 1994 NUECES ROOM, 3:00 P.M. Meeting of Accredited Standards Committee S3 on BiGacoustics to be heldjointly with the U.S. TechnicalAdvisory Group (TAG) Meetingsfor ISO/TC 43 Acoustics,IEC/TC 29 Electroacoustics, and ISO/TC 108/SC4Human Exposureto MechanicalVibration and Shock T. A. Frank, Chair S3 Penn State UniversitySpeech and Hearing Clinic, 110 Moore Building,University Park; Pennsylvania16802 R. F. Burkard, Vice Chair S3 BostonUniversity Dept. of CommunicationDisorders, 635 CommonwealthAvenue, Boston, Massachusetts 02215 P. D. Schemer,Chair, U.S. TechnicalAdvisory Group (TAG) for ISO/TC 43, Acoustics U.S. CERL,P.O. Box 4005, Champaign,Illinois 61820 H. E. von Gierke,Vice Chair,U.S. TechnicalAdvisory Group (TAG) for ISOFFC43, Acousticsand ISO/TC 108/SCA, 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), Building 233, RoomA149, Gaithersburg,Maryland 20899 StandardsCommittee S3 on BiGacoustics.The currentstatus of standardsunder preparation will be discussed.In additionto those topicsof interest,including hearing conservation, noise, dostmeters, hearing aids, elc., 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/SCAHuman Exposureto MechanicalVibration and Shock, will alsobe discussed.The Chairs of theU.S. Technical Advisory Groups for ISO/TC43 (H. E. yon Gierke),and IEC/TC 29 (V. Nedzelnitsky),will reporton currenlactivities of theseTechnical Committees and Subcommittees, includingtheir most recent meetings. (ISO/TC 108/SC4 met in Prague,Czech Republic in September1994 and ISOFFC 43 andIEC/TC 29 bothmet in London,U.K. duringNovember 1994.) Scopeof S3: Standards,specifications, methods of measuremenland lest, and terminology in the fieldsof mechanicalshock and physiologicalacoustics, including aspects of generalacoustics, shock, and vibration which pertain to biologicalsafety, tolerance, and comfort. FRIDAY MORNING, 2 DECEMBER 1994 BOSQUE ROOM, 8:30 TO 11:45 A.M. Session 5aEA EngineeringAcoustics: General Topics Murray S. Korman,Cochair Departmentof Physics,U.S. NavalAcademy, Annapolis, Maryland 21402 JanetEllzey, Cochair Departmentof MechanicalEngineering, University of Texas,Austin, Texas 78712 ContributedPapers 8:30 gument[see A. Powell,,l. Acoust.Sec. Am. 32, 982 (1960)and W. C. Meecham,ibid. 37, 516 (1965)].It showsthat there can be no dipolesound 5aEAI. Numerical simulation of the aerosound from the viscous for a largeflat surface, only the volume, quadrupole acresound. The sound layer of an impingingjet. HaM G. Alexanderand William C. generatedby thevigo•ug layer at thegurfaee ig neglected, and ia e•tamined Mcccham (Mech. Acrosp.and INucl.Eng. Dept., Univ. of California, Los Angeles,CA 90024) by ushere and shown to beindeed negligible. The simulation was carried outin twoseparate steps. The first step was to generatethe hydrodynamic Noisegenerated by a jet impingingon a surfaceis of interestin itself field whichwas comparedto well-documentedexperimental results of for suchapplications asvertical takeoff. Here we considerthe image at- similarflows. Once an adequatehydrodynamic field was generated,the 3331 d. Acoust.Soc. Am., VoL 96, No. 5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3331 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp theoreticaltreatment of Curle and Lighthill relatingsurface generated f(t)'-----c)f/c)tand IQ=-.fyx(•/•u)•dS(y).For vorticityalone, use soundand the nature of aeroacousticsound, respectively, was employed to u=V/•B, whereV2B=-• r, to get lo=f(y/•,")xdS(y)and IQ get order-of-magnitudevalues for the soundintensity and develop direc- =f(1/2)y•(y/•") x dS(y).(In 3D, constantsin theintegrals are 1, 1 and tivity patterns.The sourceregion considered was the viscous region near 1/2, 1/3, respectively.)The implicationsof theseall beingintegral results the surface.The kE turbulencemodel was employedand did a fair job of are discussed;while the vortexforce -p(•/•u) is a localflow property, depictingthe fluid field. Velocityprofiles of the free-jetregion were very (y/¾,r)is not. successful,while the modelbroke down somein the "wall jet" regionof the flow. Surfacepressure and shear stress distribution was in goodagree- 9:30 ment with experimentalvalues. The acousticvalues were then obtained andthe viscouslayer was found to generatevery low intensitylevels, in 5aEA5. Vortex sound: Equivalence of "vortex-force" and the neighborhoodof 25 dB, muchless than the volumesound. "vorticity-alone"forms. Alan Powell (Dept.of Mech.Eng., Univ. of Houston,TX 77204-4792) 8:45 A direct generalproof is offered of the equivalenceof the source 5aEA2. Two-sound-pressurestheorem for aerodynamicsound from integralsof the "vortex-force"and "vorticity-alone" formulations of aero- two-dimensionalflows. BrendaHenderson (Dept. of Mech.Eng., Univ. dynamicdipole and quadrupole sound in bothtwo andthree dimensions as of Houston,Houston, TX 77204-4792) givenin theprevious paper. For thedipole (with solid surfaces replaced by an imagesystem), take the expansionof V(a.b), a=y, b=(•r/•u), apply Thethree-sound-pressures theorem [A. Powell,J. Acoust. Soc. Am. 34, Helmholtz'equation •" +V/•(•r/•u)=0, then after somemanipulation and 902-906 (1962)] appliesto soundgenerated by inviscid,incompressible, reductionintegrate over 2-D or 3-D spaceand use Kelvin's transforma- free flows when the sourceregion is acousticallycompact and showsthat tions; finally, differentiate w.r.t. t and take the x component.For the the acousticfar field mustbe reducibleto lateralquadrupole radiation only. quadrupole,form (y-•)?y-[•(a-b)] and proceed similarly, introducing In two dimensions,the sourceregion is notcompact in thethird dimension fy.(•/•u)dV(y)'=(kinetic energy)'=0 in 3D but J'y.(•/•u)dS(y)' so it is notobvious that the three-sound-pressurestheorem directly applies =(constantor 0)' =0 in 2D. Only kinematicrelationships have been used in thiscase. The two-sound-pressurestheorem is developedby integrating apart from the foregoing hydrodynamicintegral relationshipsfor the Lighthill'ssource term over the "third" dimensionand is shownto be quadrupole.Most transparently,in 2D for the dipole, if no vorticity satisfiedby two-dimensionallateral quadrupoleradiation. In all known is generated, •' +V/•(•/•u)=D •/Dt = 0; so for moving vorti- two-dimensionalsituations, the two-sound-pressurestheorem is satisfied. city •=•0•Y-Y0), Y0=Y0(t), and •0=constant.Then the vorticity- A simpletwo-dimensional line vortexproblem involving the collisionof alone form reduces directly to the vortex force form: four rectilinearvortices is presentedas an illustration. .fy/•(•0o3"dS (y) = f(yo/•o)dS(y0) "= - .f(•ro,&u6)dS (Y0). 9:00 9:45 5aE•3. Symmetrical mode of rectangular choked jet screeeh. Dan 5aEA6. Active noise control for attenuation of low-frequency Lin and Alan Powell (Dept. of Mech. Eng., Univ. of Houston,TX broadband jet engine exhaust noise. Jerome P. Smith, Ricardo A. 77204-4792) Burdisso,Chris R. Fuller (Vib. andAcoust. Labs., Dept. of Mech.Eng., VirginiaPolytech. Inst. and State Univ., Blacksburg, VA 24061-0238),and The screechand edge tonesof rectangularjets had alwaysbeen con- RobGibson (WYLE Labs.,Arlington, VA 22202) sideredto be due to asymmetric(sinuous) jet instabilities,with out-of- phasesound fields across the jet plane.Kozu's 1991 screechmeasurements Low-frequencybroadband jet engineexhaust noise radiated into the showeda discontinuityat 2.12 • 9:15 facilityand an unsuppressedrunning jet engine.[Work sponsored by the U.S. Air Force.] 5aEA4. Vortex sound in 2D: "vortex-force" and "vorticity-alone" forms. Alan Powell (Dept. of Mech. Eng., Univ. of Houston,TX 10:00 77204-4792) 5aEA7. Theoretical evaluation of flow-induced noise in hull-mounted In thecontiguous method [J. Acoust. Soc. Am. 36, 830-832 (1964)]an sonararrays. BertrandDubus (Inst.d'Electron. et de Micro61ectron.du incompressibleinviscid flow causespressure or velocityperturbations, Pine Nord,UMR CNRS9929, D6pt. ISEN, 41 boulevardVanban, 59046 Lille or u, on geometricallydistant surface (cylinder) that drives the contiguous Cedex,France) and ChristianGiangreco (DCN-lng6nierie Sud, DLSM, externalacoustic field. Solid surfacesare replacedby someappropriate Le Brusc,83140 Six Foursles Plages,France) vorteximage system. The far field soundpressures are foundto be p(x) =[1/x/(8•r)][(ptO1/2)/(X1/2cl/2)]I•) fordipole sound, with c 3/21•for Futurehull-mounted sonar arrays are likely to be limitedby the effects quadrupoles,p=density, c = soundspeed, 1 =sinusoidalsource term (or its of flow-inducedacoustic noise on the sensors.These arrays are usually Fouriercomponent or transform)of frequencyo•, f(t)'--=f(t-x/c). constitutedby extendedsensors embedded in an elastomerlayer acting as In terms of vortex force, -p(•r/•u), where •'=V/•u=vorticity, outeralecoupler (OD) mountedon a structuralsupport plate (SSP). Predic- V2(ffin½+pu2/2)=-pV'(•/•u)leads to lo=-f(•/•u)•dS(y), with tive modelsof flow-inducednoise are obtainedby assumingspecific 3332 d.Acoust. Soc. Am., Vol. 96, No.5, Pt.2, November1994 128thMeeting: Acoustical Society of America 3332 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp mechanisms:(i) The direct path results from the detection by the sensors of Conventionallow-frequency transducers are ratherbulky, of limited thefluctuating pressures from the turbulent boundary layer after propaga- efficiency,and may sufferfrom cavitationat high sourcelevels. Plasma- tionthrough the OD [Ko eta/., J.Acoust. Soc. Am. 85, 1469(1989)]; (ii) inducedbubble transducers may offer improvementin someof theselim- the flexural noise is associatedwith the flexure of the extended sensorsvia iting factors.An implementationmethod for thesedevices that has dem- theirlateral sensitivity [Montgomery et al., J. Acoust.Soc. Am. 94, 1688 onstratedprecise energy control into the plasmahas been developed. This (1993)];(iii) The vibrating SSP radiates acoustic pressures in the near field hasresulted in the abilityto producehigh level, highspectral efficiency whichare sensedby the array.The OD and SSPare assumedof infinite soundat low frequencyin a verycompact geometry. Results are presented extentfor thedirect path and of finiteextent otherwise. This paper presents for sustainedoscillations of a large plasma-inducedbubble which has an analyticalmodel for the laterpath. Results are displayedin termsof producedtransient sound levels as high as 215 dB.This offers the oppor- wave-number-frequencyspectrum of the radiatedpressure and of fre- tunityto producevery highsound levels on a cw basis.Our experiments quencyspectral density. The relative contribution of thedifferent paths and havedemonstrated the ability to stabilizebubble motion due to buoyancy, the effectof variousparameters of the arrayare discussed. reexcitebubble oscillations with high efficiency, and the use of closed-loop feedbackcontrol for timingof energyinjection. Experimental results of the acousticoutput and bubble motion are presented. [Work supported by the 10:15 U.S. Navy.] 5aEAS. Instrumentationto generatea two-phaseturbulent (bubble) 11:0o submergedwater jet for flow noise measurements. Murray S. Korman (Dept.of Phys.,U.S. NavalAcademy, Annapolis, MD 21402) 5aEAll. Perturbation method applied to vibration monitoring of slotted beams. Xiu Ting C. Man and RobertD. Finch (Mech. Eng. It hasbeen demonstrated that the near-fieldpressure spectrum (gener- Dept., Univ. of Houston,4800 CalhounRd., Houston,TX 77204-4792) atedby a turbulentsubmerged water jet) is enhancedwhen the turbulent flowis modifiedto become a two-phaseflow containing air bubbles["Pro- Vibrationsignals can be usedin monitoringthe structuralintegrity of ceedingsof the 14thICA, Beijing,China," Acoustica 76, supplementto steelbeams. If the beamsare cracked or slotted,the resonantfrequencies No. 4, May (1992), paperB6-1, p. 70]. An amplificationfactor G will decreaseand the modeshapes will changedepending on the sizeand _ :2 :2 ß -fp •o_ph•edf/J'psi,•e_pha•edf ISmeasured asa functionof thegross void the locationof the defects.The currentstudy involves applying a pertur- fraction,8 of theair bubbles. Results showed that G-r2 andG • 20 at bationmethod in predictionof resonantfrequencies and mode shapes of a /•=0.0065. The rangeof void fractionwas limited due to the use of the slottedbeam. Modal analysistechniques are usedin estimationof modal bubblemaker (located at the jet nozzleentrance) which consisted of a parametersincluding resonant frequencies, damping, and mode shapes. frittedceramic disk that was housedin a glassBuchner funnel and fed The effectof usingthe modalanalysis method on thefrequency resolution compressednitrogen gas. It is possibleto improvethis apparatus by using will bediscussed. A large discrepancy was observed between experimental carbonatedwater at highpressure in a nozzlethat consists of an arrayof frequencyshifts and those predicted by the perturbationmethod for rela- smallholes in a thincircular plate. This arrangementcan be controlledto tively largeslots. As requiredby the methoditself, perturbationto the yield smallbubbles with an averagediameter of about100/.tin in water. system(in this caseis slot) shouldbe small,which will lead to small Largervoid fractions are possible and the necessary constraint of having changesin modalparameters. These results are comparedwith thoseob- the resonantbubble frequencies well abovethe regionof the low- tainedpreviously [Man et al., 1.Acoust. Soc. Am. 95, 2029-2037(1994)] frequencyflow noisespectrum (<500 Hz) is obtained.A briefvideotape by solvingthe exactvibration equation for a slottedbeam. It is clearthat will be shown.[Work supported in partby ONR.] the perturbationtechnique is not accurate,although it doesgive correct qualitativepredictions which are not readilyapparent with the otherap- proach. 10:30 11:15 5aEA9. The combustive sound source: Combustion and bubble dynamicstheory and experiment. JanetL. EIIzey (Dept. of Mech. 5aEA12. Flexural wave reductionusing a compliantbaffle. SungH. Eng., Univ. of Texasat Austin,Austin, TX 78712), PrestonS. Wilson, Ko (Naval UnderseaWarfare Ctr. Detachment,New London,CT 06320) andThomas G. Muir (Univ. of Texasat Austin,Austin, TX 78713-8029) A theoreticalmodel was developed to evaluatethe reduction of flexural In combustionsystems, characteristics such as adiabaticflame tem- waveswhich is generatedby a lineforce applied on an infiniteplate using peratureand laminar flame speed are highlydependent on theequivalence a compliantbaffle. The compliantbaffle layer placed between the plate ratio, which is definedas the actualfuel/oxidizer ratio dividedby the excitedby a line force and a signalconditioning plate is designedfor stoichiometricfuel/oxidizer ratio. Experimentalresults indicate that the reducingpressure fluctuations from the vibratingplate. The baffle layer acousticoutput of thecombustive sound source (CSS) also shows equiva- consideredhere is thecompliant-tube array, modeled by Junget[J. Acoust. lenceratio dependency. Peak acoustic pressure produced by CSS is low for Soc.Am. 78, 1010(1985)] to representa homogeneous (dispersive) fluid lean mixtures,rises to a maximum for near stoichiometricmixtures, and layer. Effectsof variousparameters such as the aspectratio of the com- falls for rich mixtures.Experiments were alsoconducted to comparethe pliant tube,the distancebetween tubes, and the dampingof the tubema- acousticoutput of CSS with the predictionsof Rayleigh-Willisbubble terialon the flexuralwave reduction are presented.Calculations made for theory.The measuredacoustic output of CSS follows the trend of the nondispersivefluid layer are comparedwith thosemade for the dis- Rayleigh-Willisbubble theory but alwaysfalls belowthe absolutevalues. petslyefluid layer. Energylosses that are not accounted for in thetheory are probably respon- siblefor the highpredictions. Other factors that affect the acousticoutput 11:30 of CSS are discussed,including the shapeof the combustionchamber, the sourceof ignition,the type of oxidizer and fuel, the presenceof high- 5aEA13. Rethinking the acousticscurriculum. Daniel R. Raichel pressurebubble collapses, and the generationof high-frequencycompo- (Dept.of Mech.Eng., Cooper Union, 51 AstorPI., New York,NY 10003) nents.[Work supportedby ONR.] R. BruceLindsay's classic "wheel diagram"[Acoustics: Historical and PhilosophicalDevelopment (Deaden, Hutchison and Ross,Strouds- 10:45 burg,PA, 1972), p. 2] remainsremarkably relevant today. The manifold categoriesof acousticshave not increasedin numberbut deepened,rather, 5aEAlO. High level, low-frequency, plasma-induced bubble under the impetus of current R&D spurredby easy availability of comput- transducer. Chris M. Young,Jay W. Benze, Randy D. Curry, Gary R. ers.This situationhas resulted in morematerial to coverin undergraduate Hess, Ellis L. Loree, William M. Moeny, Forest E. White, James D. andgraduate courses for studentsof engineeringand naturalsciences. The Wieting, and Niels K. Winsor (Tetra Corp., Albuquerque,NM necessityfor totalmastery of fundamentalsremains, but the question arises 87109-4512) regardinghow muchand what shouldbe treatedwithin time constraints. 3333 J. Acoust. Soc. Am., Vol. 96, No. 5, Pt. 2, November 1994 128th Meeting: Acoustical Society of America 3333 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp After a basicoverview-type course (which must include laboratory expe- independentstudy, whereby the studentcan pursuetopics of specificin- rience)at leasttwo additionalcourses should be providedin orderto terestunder professorial guidance. For architecturemajors, a special ensurethat the undergraduate student has a sufficientlystrong background coursein buildingacoustics should be a requisite--notso muchfor the in acoustics.The secondcourse might deal almostexclusively with the purposeof makingthem acousticalexperts as to inculcatein them an theoryand applicationsof ultrasonics,and the third coursecould be an awarenessof the acousticalimplications of theirwork. FRIDAY MORNING, 2 DECEMBER 1994 SAN MARCOS ROOM, 8:15 A.M. TO 12:00 NOON Session 5aNS Noise and Psychologicaland PhysiologicalAcoustics: The Annoyanceof Low-Level Environmental Sounds Daniel L. Johnson, Cochair EG&G SpecialProjects, Inc., P.O. Box 9100, Albuquerque,New Mexico 87111-9100 Dana S. Hougland,Cochair David L. AdamsAssociates, Inc., 1701 Boulder Street, Denver, Colorado 80211 Chair's Introduction4:15 Invited Papers 8:20 5aNS1. Low levelsof noiseand resolutionof their nuisance. JohnJ. Van Houten (J. J. Van Houtenand Associates, Inc., Irvine, CA 92714) Noiseordinances provide objective standards which are used in theresolution of complaints,disputes, and land use compatibility concerns.However, application of theprevailing ordinance standard may indicate that compliance exists without adequately addressing the nuisancewhich motivatedthe complaint.The frustrationof relentlessnoise and its relatednuisance can be the motivationfor litigation.Legal action may be the only remedyfor its ultimateabatement. This paperwill considerlow levelsof noise,less than the prevailingPublic agency standard, and will explorejustification for theresolution of thenuisance which they may cause. Sources of suchnoise include a neighbor'spool pump/motor or airconditioner, industrial equipment, transformers, combustion burners, pumping units,water flow in pipes,etc. Noise ordinance standards which prevail in Californiawill be reviewed,and nuisance criteria will be identified.In addition,case histories will be discussedwhich will provideexamples of theresolution of thenuisance caused by low level noise. 8:45 5aNS2.A perceivedlow-frequency sound in Taos,New Mexico. JoeH. Mullins (Dept.of Mech.Eng., Univ. of New Mexico, Albuquerque,NM 87121)and HoracePoteet (SandiaNatl. Labs., Albuquerque, NM 87185-5800) po•;•on, .... •;-*• • an ...... ;n• •.... e...... • ;.nNert•ern New Mexico,particularly in thevicinity of Taos,led to a requestby membersof theCongressional &legation of NM for an investigation.During the summer of 1993,in Taos,extensive simultaneousmeasurements were carried out of acoustic,seismic, electric, magnetic, and electromagnetic signals by a teamfrom Sandiaand Los Alamos National Laboratories, the Air ForcePhillips Laboratory, and the University of New Mexico.Since anecdotal evidenceand signal matching tests by the hearers implicated the frequencies between 30 to 100Hz, specialattention was given to that range.However, no signals were found matching the description, and in particularno airborneaudio signals in thisrange were found otherthan background, even though the acoustical detector was capable of measuringsignals less than -50 dB SPL.Subsequent complaintsof similarsounds from widely distributed areas in theU.S., anda longhistory of thesein theU.K. JR.N. Vasudevanand C. G. Gordon,Appl. Acoust. 10, 57-69 (1977)]have focused attention on human hearing in the20-100 Hz range.New instruments arebeing developed and controlled clinical tests are plannedwith hearersand nonhearers in theTaos area. 9:10 5aNS3.Low-frequency acoustic measurements at Los Alamos. RodneyW. Whitaker(Los Alamos Natl. Lab., EES-5 MS F665, LANL, LOsAlamos, NM 87545) LOsAlamos National Laboratory has had an active program of atmosphericinfrasonic measurement forthe last 10 years,in the frequencyregion of 0.1-10Hz. Duringthis time, substantial data have been gathered on acoustic signals from underground nuclear tests,earthquakes, and large conventional explosions, often at longrange. Normal operational activity, issues of long-rangepropaga- tion,and interesting data examples will be discussed.Recent work related to a low levelenvironmental noise problem will alsobe presented. 3334 d.Acoust. Soc. Am., Vol. 96, No.5, Pt.2, November1994 128thMeeting: Acoustical Society of America 3334 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 9:35 5aNS4.Low level,low-frequency sounds: Measurement and analysischallenges, Alfred J. Bedard,Jr. (Natl. Oceanicand AtmosphericAdmin., Environmental Technol. Lab., 325 Broadway,Boulder, CO 80303} Low-frequencysounds from both natural and civilization sources can travel for longdistances (tens or hundredsof kilometers), producinglocal regions of enhancedas well asreduced intensity depending upon range and time. Thus the idenlification of sources canbe difficult, since merely mapping sound level in thedirection of increasingintensity may nol help to identifydistant sources. A briefreview of someexamples of low-frequencybackground sounds provides the basis for a discussionof potentialmethods for identifyingsound sources in a complexpropagation environment. At low frequencies(<100 I-[z) it is moredifficult to determine directionwith simple,portable systems. Some practical approaches for low-frequencysource location are described. 10:00-10:15 PANEL DISCUSSION 10:15-10:30 Break ContributedPapers 10:30 Automatedmonitoring of low level ambientnoise levels presents many challenges.The obviouschallenge is to havea noisemonitor with a low SANS5.Response of nat'onal park visitorsto the soundsof aircraft noisefloor, lessthan 20 dBA, so that the ambientcan be monitored.Other overflights. William E. Robert (HarrisMiller Miller & Hanson,Inc., 15 challengesinclude designing a lightweightsystem that canbe backpacked New EnglandExecutive Park, Burlington, MA 01803) to the monitoringsite, and the siteselection. Site selectioncriteria include The responsesof over 750 nationalpark visitorsto soundsof aircraft protectingthe monitor from direct sonlighl and heal, and locatingthe overflightswere measured at six studyareas in the GrandCanyon, Hawaii microphoneso that the influenceon the measurementsfrom rustling leaves Volcanoes,and Halcakala National Parks. Park visitors were observed as andwind will be minimal.This paperpresents the resultsof our learning they enteredeach study area, and were askedto participatein a brief curve from three studies of low level ambient noise. surveyas they exited the area. The surveyincluded questions about the visitor'sreasons for visitingthe park,and asked visitors to ratetheir re- sponsesto aircraftsounds on five-pointscales. Simultaneously, in one to 11:15 three positionsrepresentative of the study area,A-weighted soundlevels were recurdcdat l-s intervalsusing extremely low noiseinstrumentation. 5aNSS. Homeownerjudgments of the annoyanceof individual heavy In addition,human observers maintained time-synchronized logs of air- weapons blasts. George A. Luz, Nelson D. Lewis, and William A. craft audibility,lypes of aircraftaudible, types of backgroundsounds, and Russell,.It. {Bio-AcousticsDiv., U.S.Army Ctr. for HealthPromotion and otherfactors. Several mitigating variables, such as backgroundsound level PreventiveMedicine, Aberdeen Proving Ground, MD 21010-5422) andvisitor expectalions, were testedfor theirability to improvethe dose- Paststudies of the annoyanceof heavyweapons noise have shown the responserelationships. Logistic regression was used to generatefour sepa- relationshipbetween the yearlyaverage exposure and averageannoyance ratedose-response relationships, relating two visitor responses (annoyance as reportedby residents.However, no one hasreported the relationship due to aircraft sounds,and interference of aircraft sounds with natural betweenindividual weapons blasts and the annoyancereported by home- quiet}to two acousticdoses (percentage of time aircraftarc audible,and ownerswho were experiencing these events inside their own home. As part aircraftA-weighted equivalent sound level). [Work supported by National of a noise and vibrationmeasurement study undertakenin responseto ParkService.] communitycomplaints, four homeownersmade judgments of the annoy- anceof heavyweapons noise. When these judgments were plotted against 10:45 the outdoormeasured linear peakSPL, "moderateannoyance" was found to beginjust above 115 dB. This finding is consistentwith a reportby L. 5aNS6. Long-term, low-cost noise monitoring systems. Eric V. D Pater in 1976 that there was a low probabilityof complaintsfrom McKinneyand Robert D. Brace (Colloborationin Sci.and Technol., Inc., residentsliving in thevicinity of theNaval Surface Weapons Center, Dahl- 15835 Park Ten Place, Stc. 105, Houston, TX 77084-5131} gren,VA, if weaponsblasts were below 115-dB peakat the complainant's home. Long-termnoise monitor. ing hasbeen possible in thepasl with large, expensivesystems which were designed to withslandharsh environmental conditionsincluding rain and cold temperatureswhile recordingseveral monthsworth of intervaldata. For the past7 years,CSTI and othershave 11:30 experimentedwith the useof noisedosimeters for outdoormeasurements, 5aNS9.Annoyance of individualvehicle pass-by noise for light and monitoringsound levels for a few days up to 6 months.In order to use heavy vehicles. Niek J. Versfeld,Joos Vos, and Frank W. M. Geurtsen thesemonitors in thefield, however, consideration must be givento issues (TNO HumanFactors Res. last., P.O. Box 23, 3769 ZG Soesterberg,The suchas how to protectthe monitor and download the data since dosimeters Netherlands) are not sold as part of an integratedoutdoor monitoring system. A water- proof,tamper-proof enclosure which holdsthe monitorand externalbat- A laboratoryexperiment has been conductedto assessthe noisean- teD',and a mastto positionand protect the microphoneare essenlialele- noyanceof individualvehicle pass-bys as a functionof soundlevel. Ve- mentsto sucha system.Data downloading may be performedin the field hicletype varied from passenger cars to heavytanks. Results showed that with a portablecomputer or overa phoneline. This paperwill summarize for each individualvehicle type, the A-weightedsound exposure level experiencesat solvingsome of the problems. (SEL) wasthe mostimportant predictor of the annoyance.However, at a givenannoyance, the differencein level betweendifferent vehicle types I1:00 couldbe as high as 11 dBA SEL. The diffcrcucein level betweenthe high-frequencypart and the low-frequency part of thespectrum seemed to SANS7. Automated monitoring of low level ambient noise levels. play a role in the annoyance,in thatsounds containing relatively much NelsonD. Lewisand William A. Russell,Jr. (EnvironmentalNoise Prog., high-frequencyenergy (e.g., passenger cars) were judged as beingmore U.S. Army Ctr. for Health Promotion and Preventive Medicine annoyingthan those having relatively much low-frequency energy (such as (Provisional},Aberdeen Proving Ground, MD 21010-5422) tanks).[Work supported by the Ministryof Defence.] 3335 J. Acoust.Soc. Am., VoL 96, No. 5, Pt. 2, November 1994 128th Meeting:Acoustical Society of America 3335 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 11:45 Resultsshowed that, at a fixedequivalent sound level, and with the number of vehicleskept constant, annoyance hardly depended on the durationand 5aNS10. Effect of silent periods having short or long durations on positionin timeof thesilent period. In thesecond experiment subjects had the annoyanceof Vehiclesounds. Niek J. Versfeld,Joos Vos, and to comparethe annoyance of roadtraffic sounds with thatof soundsfrom Frank W. M. Geurtsen (TNO Human Factors Res. Inst., P.O. Box 23, heavy vehicles(such as tanks).In decidingwhich fragmentwas more 3769 ZG Soesterberg,The Netherlands) annoying,the subjectshad to imaginethat they were exposedto the road Two laboratoryexperiments were performedto studythe effect on trafficsounds throughout the year,whereas the soundsof heavyvehicles annoyanceof noiseconcentration in time. The first(rating-scale) experi- were only audibleduring a certainpart of the day,week, or year.Results mentdealt with the influenceon annoyanceof short-timesilent periods indicatethat, at a givenequivalent sound level, concentration of thesounds (varyingfrom 0 to 160s) in pass-byvehicle noise of 240-stotal duration. in timereduces annoyance. [Work supported by theMinistry of Defence.] FRIDAY MORNING, 2 DECEMBER 1994 SABINE ROOM, 8:15 TO 11:45 A.M. Session 5aPA PhysicalAcoustics: Scattering and Elastic Wave Propagation Paul E. Barbone, Chair Departmentof Aerospaceand MechanicalEngineering, Boston University, Boston, Massachusetts 02215 ContributedPapers 8:15 resonance'smanifest themselves as maximumamplitude returns while for thin shellsthey manifestthemselves as minimumamplitude returns. The 5aPA1. Eigenfunction and eigenvalue analysis of scattering effectwith the transitionalnature of a rigidlikebackground is associatedto operators. T. DouglasMast andRobert C. Waag (Dept.of Elec.Eng., a softlikebackground for the two extremesso that the returnsignals vary Univ. of Rochester,Rochester, NY 14627) in theircoherence from addingconstructively to addingdestructively over Acousticscattering by a given inhomogeneitycan be compactlyde- the thicknessvariation. The sensitivityof resonancelocations as a function scribedby a scatteringoperator. This operatoracts on the transmitted of theelastic parameters is also presented. [Work sponsored by NRL and acousticfield to yieldthe scatteredacoustic field on a measurementsur- ONR.] face. For scatteringat fixed frequency,the operatoris knownto admita basisof eigenfunctions.When a finite numberof transmitangles and re- 8:45 ceivingpoints is considered,the scattering operator can be representedas a matrix with an associatedbasis of eigenvectors.The presentpaper re- 5aPA3.Do pseudo-Scholteresonances exist? M.F. Werby (NavalRes. ports an investigationof the relationshipbetween these eigenfunctions, Lab., Code 7181, StennisSpace Center, MS) and N.A. Sidorovskaia eigenvectors,and associated eigenvalues and the characteristics of scatter- (Univ. of New Orleans,New Orleans,LA) ing objects,including their location, size, shape, orientation, and strength. In a pioneeringwork Talmantet al. [J. Acoust.Soc. Am. 86, 278 Scatteringoperators are derived analyticallyfor axisymmetricscatterers (1989)] establishedthe presenceof pseudo-Stonelyresonances excited suchas cylinders;in thiscase, the eigenfuncfionsof the operatorstake on when acousticalsignals scatter from shells at or near coincidencefre- simpletrigonometric forms. Connections are notedbetween the eigenval- quency.This notionwas supportedby the argumentthat StoneIcywaves uesand eigenfunctionsof the scatteringoperators and the basisfunctions exist at the fluid-elasticinterface of a platewhen water is on one sideand thatappear in orthogonalfunction representations of the scatteredfields. the other side is evacuated.It is known that nondispersivewaterborne Scatteringmatrices for arbitraryscatterers are calculated using a coupled finite-element/integralequation method due to Kirschand Monk lIMA J. wavesare excited at thefluid-water interface for thatcase in thefrequency Num.Anal. (to appear)].Examples of the relationshipbetween scatterer region aroundcoincidence frequency. This coincidedwith the bounded shell casein which very narrowstrong resonances corresponded with the propertiesand eigenvaluesand eigenvectorsof the scatteringmatrix are waterbornewaves and a broad envelopefunction corresponded with the presented. onset of the flexural resonances which become manifest at coincidence frequencywhen the flexuralwaves become supersonic and thusradiated 8:30 into the water.The envelopeeffect corresponds to an abruptphase change of pressureat coincidencefrequency. An analogousargument predicts the 5aPA2. Evidence for the existence of strong bending modes for existenceof pseudo-Scholteresonances. The analogfor thatcase is a plate signalsscattered at oblique incidencefrom spheroidalshells. M.F. in whichfluids of like propertiesexist on both sides.In that casewater- Werby (Naval Res. Lab., Code 7181, StennisSpace Center, MS) and bornewaves exist over the entirefrequency range. The implicationis that N. A. Sidorovskala (Univ. of New Orleans, New Orleans, LA) if one scatters from such an object there should be a proliferation of In anearlier work [Werby et al., J.Acoust. Soc. Am. 85, 2365(1989)] waterborne waves and thus for closed shells an abundance of resonances it was establishedthat bending(flexing) modes are excitedfor signals associatedwith waterbornewaves circumnavigating the shell shouldby scatteringat obliqueincidence from solid spheroidal shells. This was ac- present.Can the abundanceof sharppeaks excited on fluid filled shellsbe complishedby comparingthe exact T-matrix resonancepredictions with explained in terms of this mechanism?This issue is examined and the thosepredicted from Timoshenkobeam theory which accuratelypredicts questionis answered.[Work sponsored by NRL andONR.] the bendingmodes of a bar. One mustthen ask, do suchmodes exist for shells?One wouldexpect that for fairly thick shellssuch modes do, but do 9:00 they exist for thin shellstoo? In this studyscattering of acousticalsignals from elasticshells of variousmaterials, aspect ratios, and shell thicknesses 5aPA4.The studyof pulsesignals from elasticspheroidal shells near are examined.The studydoes indeed demonstrate the presenceof bending reflectinginterfaces. N.A. Sidorovskaia(Dept. of Phys.,Univ. of New modeseven for very thin shells.It is interestingthat for thick shellsthe Orleans,New Orleans,LA), CleonDean (GeorgiaSouthern Univ., 3336 d. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128thMeeting: Acoustical Sociebj of America 3336 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp Landram,Statesburo, GA 30460),and M. K Werby (NavalRes. Lab., 9:45-10:00 Break StennisSpace Center, MS) 10:00 A formulationis presentedthat allows one to describebackscattered echoesfrom elasticshells near pressure release and rigid interfaces.This 5sPA7. A new generalizedk-space (GkS) method for transient formulationis alwaysconsistent even at low frequenciesand largedis- elastodynamic scattering problems. Qing-Huo Liu tancesfrom the interfacesand allows for the rapidreproduction of back- (Schlumberger-DollRes., Old QuarryRd., Ridgefield,CT 06877) scatteredechoes over frequencyranges of practicalinterest. Numerical A conventionalapproach to simulatingtransient elastic wave propaga- resultsare examinedfor pulsesignals sealtoting from varioustargets as a tion in inhomogeneousmedia has been the finite-difference(FD) method. functionof targetmalerial, dislance from the interface,and the effectthai However,the FD methodrequires a large numberof grids in order to thetwo interface extremes have on thedetected signals. [Work sponsored obtain accurale results. This is because in conventional FD schemes, by NRL andONR.] second-order(sometimes higher-order) differences are usedto approxi- matethe spatial derivatives. In thiswork, a newgeneralized k-space (GkS) methodis describedfor elastodynamicscattering problems. From its inte- 9:15 gral representationin spatial-frequency (r-f) domain,a localequation is derivedfor Ihe displacementfield in spectral-frequency(/•-f) domain. 5aPAS.Acoustic scattering from a rigid spherecoated with multiple This equationbecomes a time-convolutionequation in spectral-time(k-t) layersof absorbingmaterials: Eigenfunctionexpansion method. B. domain.Using two temporalpropagators, compressional and shear,this S. Sridhara(Ind. StudiesDept., Middle Tenn. State Univ., Murfreesboro, time-convolutionequation can be convertedinto two lime-steppingequa- TN 37132) and SadasivaM. Rao (Auburn Univ., Auburn, AL 36849) tions, which becomemuch easierto solve. Hence, at each time step, the solution is first obtained in the k-t domain, and then transformed to the r-t Far-field scatteredproperties for a rigid spberecoated with several domainby usingspatial FFT. Since the G/•S methoduses the Fourier layersof absorbingmaterials have been obtained using Ihe eigenfunclion transformto representIbe spatialderivatives, it is muchmore accurate than expansionmethod. The spherecoated with m numberof acousticlayers the FD method.Numerical examples show that the GkS methodwith only and placedin air, in a losslesssituation, was considered.Compatibility fourgrids per wavelength can achieve the same accuracy as the FD method conditionsof soundpressures and soundvelocities were appliedat layer with 16 gridsper wavelength. interfaces.The resulting(2re+l) complexlinear algebraic equations in- volvingmaterial properties, and the sphericalBessel, Newman, and Han- 10:15 kel functions,were written in the matrixform. Computercodes were de- velopedand the equalionswere solvedfor Ihe coefficientswhich, along 5aPA8. Large-scale3D finite-differencesimulation of elastic wave with othervariables and paramelers,were usedto computethe scattered propagationin boreholeenvironmenls. Qing-HuoLiu, Eric Schoen, field properties.The formulationwas verified by computingthe far-field Franqois Daube, Curt Randall, Hsui-lin Liu, and Ping Lee scalteredparameter and comparingit with the availablestandard results. (Schlumberger-DollRes., Old QuarryRd., Ridgefield,CT 06877) Far-fieldscattered properties were computed for a rigidsphere coaled with Elasticwave propagationin realisticborehole environments is very a tolal of 12 differentlayers. In eachcase, the magnitudeof the far-field complexbecause of the presenceof borehole,dipping beds, and other scatterparameter was computed and plotted as a functionof the anglein irregularscatterers. In orderto underslandthis complex wave propagation Ibe rangefrom 0 ø to 180ø. II wasobserved Ihat thescatter parameter was phenomenonfor soniclogging applications, a three-dimensionalfinite- sensitiveto the changein the angleand Ihe variationwas relativelylarge difference(FD} methodwas used to simulateelastic wave propagationon in therange from 100ø to 160ø in thecase of certainlayers. a parallelcomputing archilecture. The FD schemesolves the first-order elaslicwave equations with centraldifferencing in bothspace and time via staggeredgrids. Liao's absorbingboundary condition is usedto reduce 9:30 artificial reflectionsfrom the finite computationaldomain. In this work, uniformgrids in Cartesiancoordinates are usedto discretizethe inhomo- 5sPA6. Comparison of experimentally obtained and theoretically geneousmedium. Because of the staircaseapproximation of the circular predicted signature features in returned echoes from submerged borehole,it is observedIhat the discretizationrequiremenl is quitedifferent targets insonified by short, broadband pulses. Hans C. Strifors, for monopoleand dipolesources. Several methods are suggestedto rem- Torbj6rnSt•hlsten (Natl. DefenseRes. Establishment,S-17290 edy thisproblem. The resultsfrom the FD methodwere validated by other Stockholm,Sweden), and Guillermo C. Gaunaurd (Naval Surface methodsavailable for severalspecial geometries. Numerical examples will WarfareCtr., Silver Spring, MD 20903-5640) be shown to demonstrate the interaction of elastic waves with borehole and thesurrounding geologic structures. Applications to interpretationof sonic Backscatteredechoes are studiedfrom submergedelastic targets in the loggingwill be illustrated. frequencyand time-frequency domains when the targets are insonified by short,broadband sound pulses. The combinedtime-frequency approach 10:30 seemsto give the mostinformation since it canshow the time evolutionof the resonancefeatures that identify eachtarget. The targetsare either an 5sPA9.Three-dimensional dyadic Green's funclion for elasticwaves air-filledspherical shell or varioussolid brass or steelspheres. The incident in multilayercylindrical structures. Cai-ChengLu (Dept.of Electrical waveformis generatedby weightinga sinusoidalsignal with a Blackman andCornput. Eng., Univ. of Illinois,Urbana, IL 61801) and Qing-Huo time window of a few cycles width. Experimentallyobtained data are Liu (Schlumberger-DollRes., Old QuarryRd., Ridgefield,CT 06877) processedin the time-frequencydomain using a pseudo-Wignerdislribu- Multilayercylindrical structures are encountered in manyapplications. tion (PWD). The associatedtime window is Gaussian, and its width is Elasticwaves generated by an arbitrarysource in sucha structurecan be adjustedto suppressthe interferenceof cross-termsin the PWD, yet re- foundby usingthe corresponding three-dimensional dyadic Green's func- tainingIhe desired property of time-frequencyconcentrating the exitacted tion.In Ihiswork, a 3-D dyadicGreen's function for thedisplacement field features.Each PWD is displayedin a 3D surfaceplot usingprogressively is derivedfor elasticwave propagationin coaxialcylindrical structures lightercolor shades (pseudocolors) determined by theheight of thesurface with an arbitrarynumber of layers.The primaryand reflection parts of the (or the magnitudeof the PWD), and that surfaceplot is alsoprojected onto dyadicGreen's function are firstwritlen in termsof the Fouriertransform the lime-frequencyplane to producean informative2D intensityimage of z (axial coordinate)and Fourier seriesof 0 (azimuthalcoordinate). in plot. For eachlarger, Ihe time developmentof significantresonance fea- this transformdomain, the boundaryconditions are Ihen imposedso that luresexlractcd from returnedechoes is examinedand favorablycompared the reflectioncoefficients can be calculatedfor eachk z andn, whichare, with the correspondingtheoretically predicted PWD signalures. respectively,the transform variables of z and0. The spatialdyadic Green's 3337 J. Acoust.Soc. Am., VoL 96, No. 5, Pt. 2, November1994 128th Meeting:Acoustical Society of America 3337 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp functionis then obtainedby inversetransforming this solutionin kz-n eralizedto transducers'arbitrary orientation, multilayered and cylindrical domain.Once this dyadicGreen's function is found, elasticwaves due to configurations. any sourcein the cylindricalstructure can be obtainedby integratingthe Green's function with the source. The numerical results are validated 11:15 againstprevious results for specialgeometries. Several applications of this 5aPA12. Transmitted beam distortion and rotation due to mode dyadicGreen's function will be shownfor layeredstructures commonly conversion between acoustic and shear waves at liquid-solid usedin acousticwell logging. interfaces.B.J. Landsberger,M. F. Hamilton,and Yu. A. Winsky (Dept. of Mech.Eng., Univ. of Texasat Austin,Austin, TX 78712-1063) 10:45 An experimentwas performed with a pulsedsound beam incident on a 5aPA10. Leaky Rayleigh wave scattering from elastic media with 6-cm-thick aluminum block immersed in water. Tone bursts were radiated microstructure.Yuan Zhang and RichardL. Weaver (Dept.of Theor. at 1 MHz by a circularsource of radius1.2 cm, whichwas positioned10 andAppl. Mech., Univ. of Illinois,216 TalbotLab., 104 S. WrightSt., cm away from one sideof the block. Transmittedacoustic beam patterns Urbana, IL 61801) were measuredin the water beyondthe oppositeside. Attention was de- voted to anglesof incidencein the neighborhoodof the critical anglefor Scatteringof leaky Rayleighwave from a flat fluid-solid interfaceis compressionwaves in the block (•13.5ø). The use of pulses,and the studied.The fluid half-spaceis takento be ideal andhomogeneous while strongrefraction of the compressionwave in the block, enabledisolation the solidhalf-space has randomly inhomogeneous anisotropic elastic con- of effects associated with the shear wave. Distortion in the form of mul- stantsdue to the microstructureof the material.For planewaves incident tiple beam splitting,and up to 4ø increasein the effectivepropagation from the fluid ontothe interfaceat the criticalRayleigh angle, the singly directionof the transmittedbeam (relativeto the angieof the incident scatteredincoherent field is obtainedby utilizinga first Born approxima- soundbeam), were observed.Computations based on standardFourier- tion. When the solidis a crystalaggregate and when the correlationfunc- transformtechniques, but excludingcontributions due to the compression tionis of exponentialform, the mean-square scattered signal level is found wavein theblock, yield good quantitative agreement with experiment.For to be inverselyproportional to the dimensionlessfrequency in the high- the conditionsin this experiment,calculations indicate that the distortion frequencylimit but proportionalto the third powerof frequencyin the and rotationof the transmittedsound beam are due mainly to the mode low-frequencylimit. Numericalresults are given for water-aluminumin- conversionat the secondinterface. [Work supportedby AASERTand terfacescattering. [Work supported by NSF.] ONR.] 11:00 11:30 SaPAll. An asymptotic model for compressionaland shear wave 5aPA13. A model of a confocal ultrasonic inspectionsystem for excitation in plates by ultrasonic transducers. SmaineZcroug and interfaces. E. Yogeswarenand JohnG. Harris (Theor.Appl. Mech. FredE. Stanke (Schlumberger-DollRes., Old QuarryRd., Ridgefield,cr UIUC, 216 TalbotLab., 104 S. WrightSt., Urbana,IL 61801) 06877) A mathematicalmodel describing how a confocalarrangement of two Pulsedbeams excited and detectedby ultrasonictransducers are rou- focusedultrasonic transducers is usedto interrogatea complexinterface tinely used to characterizeelastic structures.An efficient model for betweentwo materialsby scanningthe focal point acrossthe interfaceis transducer-structureinteractions is presentedand appliedto transmission outlined.A complexinterface is one that has roughnessand partial contact througha fluid-loadedplate with a transmitter-receiverpair. Each trans- at severallength scales,many of which are equal to or smallerthan the duceris modeledas severalcomplex-transducer points (CTPs) [Zeroug wavelengthin the material.When the focusedultrasound strikes such an et al., Reviewof Progressin QNDE, editedby Thompsonand Chimenti interface,though the focal regionbe small,multiple scattering takes place (Plenum,New York,1994), Vol. 13], whichbehave as reciprocal, electroa- among the scattererswithin and adjacentto the focal region, making it coustic quasi-Gaussiantransducers. The interaction of each CTP unclearhow the interfaceis beingsampled. To clarify this issuea specific transmitter-receiverpair with theplate is solvedby wave-numberspectral interfacemodel, consistingof a planar array of multiple small cracks decompositionand ray expansions, resulting in a sumof multiplyreflected havingarbitrary lengths and spacings,is used.This interfaceis interro- beamspropagating within the plate.The resultingtime-harmonic beam gatedby a focused,antiplane shear wave. The modelshows that what is integralsare approximatedasymptotically and transformedto the time measuredare the multiplyscattered signals averaged over the apertureof domainto yieldthe received voltage as a finitesum of multiplyreflected the transducer,and that the dominant contribution comes from the scat- compressional(P), shear(S), andcoupled (P-S) arrivals.Comparison tered signalsthat phasematch to the interrogatingsignal. Expressions with experimentsshows that (a) threeCTPs accuratelymodel the fiat relatingthe modeledreflected and transmittedsignals to the convolutionof circulartransducers, (b) the efficientasymptotic solution is accuratewhen the incidentwave field with the crack-openingdisplacements at the focal the observedarrivals are distinctin time, and (c) at normalincidence, the region are given. Numerical examplesare worked out for similar and S and P-S arrivalswhich are excitedby the transducers'finite spectrum contrastingmaterials on eachside of theinterface. [Work supported by the necessitatehigher-order asymptotic expansions. This approachcan be gen- NSF.] 3338 d. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3338 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp FRIDAY MORNING, 2 DECEMBER 1994 PECOS ROOM, 8:30 TO 11:45 A.M. Session 5aSA StructuralAcoustics and Vibration: Numerical and Analytic Methods CourtheyB. Burroughs,Chair Applied ResearchLaboratory, Pennsylvania State University,P.O. Box 30, State College,Pennsylvania 16804 ContributedPapers 8:30 9:00 5aSAI. An acoustic boundary element method using 5aSA3. Radiation sensitivity of baffled plates to structural analytical/numerical matching applied to a fluid loaded plate. perturbation. StevenR. Hahn and Aldo A. Ferri (Mech. Eng. Dept., RonaldJ. Epsteinand Donald B. Bliss (Mech.Eng. and Mater. Set., Duke GeorgiaInst. of Technol.,MS 0405, Atlanta,GA 30332) Univ., Box 90300, Durham,NC 27708-90300) The analysisof acousticradiation and scatteringfrom submergedelas- tic structuresis an importantand challengingproblem. Often, numerical Analytical/numericalmatching (ANM) is a hybridscheme combining a solutionsare hamperedby the fact that the acousticpressure field can be low-resolutionglobal numerical solution with a high-resolutionlocal ana- very sensitiveto structuraldetail. In thispresentation, a baffled plate sub- lytical solutionto form a compositesolution. ANM is appliedto a har- mergedin a semi-infiniteacoustic medium is usedstudy this sensitive. A monicallyvibrating flat platein two dimensionsto calculatethe radiated finiteelement description of thestructure and a boundaryelement descrip- acousticfield and the associated fluid loading. The problemutilizes over- tionof the fluidare used to modelthe plate-fluid-bafflearrangement. The lappingsmoothed doublets, and local corrections to calculatethe doublet sensitivityinformation is obtainedby applyingperturbation techniques to strengthdistribution along the plate.A smoothinglength scale is intro- the matrixequations that arise,yielding exact derivatives of the chosen ducedthat is largerthan the smallestphysical scale, and smallerthan the fieldvariable. Several types of localstructural perturbations (point masses, largestphysical scale. The global low-resolutionsolution is calculated springs,dampers, and ribs) as well as global perturbations (Young's modu- numericallyusing smoothed doublets, and convergesquickly. Local cor- lus, density,damping) are considered.The natureof the structuralsensi- rectionsare donewith high-resolutionlocal analyticalsolutions. The glo- tivity is examinedand some investigationis made into what types of bal numericalsolution is asymptoticallymatched to the local analytical structuralfeatures have the greatestimpact on radiationand scattering. solutionsvia a matchingsolution. The matchingsolution cancels the global Finally,the useof thesensitivity information for engineeringand design is solutionin the near field, and cancelsthe local solutionin the far field. The discussed. methodis very robust,offering an insensitivityto collocationpoint posi- tion.ANM provideshigh-resolution calculations from low-resolutionnu- 9:15 mericswith analyticalcorrections, while avoidingthe subtletyinvolving singularintegral equations, and their numerical implementation. [Work 5uSA4, Minimization of the sound power radiated by a cubic supporledby ONR.] structurerising velocity constraints. DanielH. Kruger,J. Adin Mann, III, andTed Weigandt (2019 BlackEng. Bldg., Iowa StateUniv., Ames, Lq 5O011) 8:45 Soundpower radiated by a cubic structureas a functionof normal 5aSA2.A 3-D finite elementmodel for soundtransmission through a surfacevelocity was written using the boundary element method [K. A. double-plate system with isotropic elastic porous materials. Cunefareand G. H. Koopman,J.Vib. Aconst. 113, 387-394 (1991)]. This RaymondPanneton, Noureddine Atalla (G.A.U.S., D6pt. G6nie functionwas minimized by a gradientmethod with linearand second-order Mi•canique,Univ. de Sherbrooke,Sherbrooke, PQ IlK 2RI, Canada),and velocityconstraints. The constraintswere formulatedto reflectphysical J.-F. Allard (Univ. du Maine, Le Marts,France) limitationsin the abilityof constrainedlayer damping material to modify structuralvelocity. Complex velocity phase was held constantwhile am- plitudewas allowed only to decrease.Initially, simulated velocity patterns The predictionof soundtransmission through multilayer structures is wereused to testthe method and software created. Sound power reductions of utmostimportance in aircrafts,buildings, and other engineering appli- of 3 dB were achievedwhile modifyingthe normalvelocity amplitude over cations.In view of optimizingthe transmissionloss, the finite clement only 0.46% of the surfacearea of the cubeat a singlefrequency. Later, methodis an interestingmcan to modelsuch structures since it permitsone velocityof a real structurewas measuredusing a laservibromcter. Mini- to accountfor complexstructure geometries and to modelaceumtely the mumsound power and correspondingvelocity distributions were calcu- boundaryconditions. In this paper,a 3-D-finite elementmodel is devel- laledfor nondimensionalka ranging from 0.5 to 3.0. [Worksupported by opedto evaluatethe normalincidence transmission loss through a double- NSF, ContractNo. MSS-9103377.] platesystem with cavity absorption. The cavityis filledwith an air- saturatedisotropic elastic porous materials. The modeluses a two-field finiteelement procedure for the porousmedium based on the Biot theory. Sincethe Blot theoryconsiders only the energydissipation due to the 5aSAS.Structural intensity in an infinitecylindrical shell driven by viscouseffects, the frequency-dependent bulk modulusof the air,worked normal forces. DonaldJ. McDowell, Jr. (Naval UnderseaWarfare Ctr., outby Champouxand Allard [J. Appl.Phys. 70, 2182-2191(1991)], is 9:30 adoptedto accountfor the energydissipation duc to thermalexchanges. 06320). CourtheyB. Burroughs (Penn State Univ.. State College, PA Also, two acta of field variables are considered: the u-U and the u-P sets, Div.Newport, DetachmentNewLondon, Code 423,New London, CT 16801), and CarlosM. Godoy (Naval UnderseaWarfare Or., Newport, whereu andU arethe solid and fluid displacements and P is thepore-fluid RI 02841) pressure.Both approaches are developed and compared through numerical simulations.[Work supportedby Bombardier,Inc., Canadair,and The structuralintensity formulation provided by Williams[J. Acoust. N.S.E.R.C.] Soc.Am. 89, 1615-1622 (1991)] is usedto considerthe flow of power 3339 J. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128th Meeting:Acoustical Society of Amedca 3339 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp alongan infinitelength, thin cylindrical shell driven by a harmonicforce becauseof its frequencydependence. The transformationprocess results in appliedin theradial direction. Finite element modeling is usedto showthat a linearsystem that is generallyreduced in order,having a sparsesym- the activecomponent of the time-averagedintensity oscillates with respect metric coefficientmatrix amenableto the use of a profile solver.The to the axial coordinateof the shell at a wave numbergiven by the differ- procedureis demonstratedon numericalexamples in three dimensions. ence betweenthe bendingand longitudinalwave numbers.The reactive [Worksupported by ONR.] componentof the intensityalso oscillatesat this rate and is in phase quadraturewith theactive component. This suggeststhat the total power at 10:45 anypoint along the shell is constantand power is exchangedbetween wave types.The stored(reactive) power is shownto be associatedwith circum- 5aSA9. Wavelet frame expansionsand wavelet responaefunctions. ferentialexpansions and contractionsof the shell. Taxer•nsay (Dept.of Mech.Eng., Michigan State Univ., East Lansing, MI 48824) 9:45 Waveletframe expansions are utilizedto introduce"wavelet response 5aSA6. Balance of energy between scattered and reflected waves functions"(WRF). The convolutionintegral is replacedby an efficient resultingfrom an axial surfacewave incidenton a discontinuityof a synthesisscheme by incorporatingmultiresolution and waveletframe ex- fluid-loadedcylindrical shell. StevenL. Means (GraduateProg. in pansionconcepts. Wavelet frame expansionis usedto partitiona wide Acousl.,New ARL Bldg.,Penn State Univ., University Park, PA 16801) spectralrange into multiresolutionfrequency bands. The responsefrom each resolutionlevel is obtainedby using a samplinginterval that is There is a branchof the dispersioncurve of fluid-loadedcylindrical matchedwith the bandwidth.The contributionscoming from different shellsin which fluid massand an "effective"spring stiffness balance at resolutionlevels are combined to constructthe overall system response. in low frequencies.This leadsto a surfacewave with a wavenumber which the applications,the attentionis focusedon the synthesisof the transient becomesincreasingly close to the acousticwave numberas the frequency time-domainvibration response of proportionallydamped (B,,=•/, tendsto zero. Whensuch a surfacewave, propagatingalong the axisof the n =modes)wideband linear systems. Naturally, such systems, having im- cylinder,is incidenton a shelldiscontinuily, energy is scatteredback along pulseresponse durations that are inverselyproportional to the modalband- the cylinder's axis and into the surroundingfluid. The presentpaper ex- widths(T•,, = 2.2/B,), requirea multiresolution synthesis scheme dur- aminesthe balanceof the energybetween the reflectedand the scattered ing the constructionof their transient response,which involves fast- waves.Comparisons are madewith analogoussurface waves scattered by decayinghigh-frequency components that are superimposedon top of a discontinuityof an elasticplate on an elasticfoundation. slowly decayinglow-frequency modal responses. The proposedconstrue- lion techniqueaverts the time-domainaliasing problem associated with the 10:00-10:15 Break DFT schemes.The effectivenessof the waveletframe synthesis scheme is demonstratedby consideringthe constructionof the transientvibration responseof a finite dispersivesystem. 10:15 5aSA7. A numerical experimenton the couplingof structural-borne 11:00 sound into an aircraft interior. Brian H. Houston, Martin H. Marcus, Earl G. Williams,Douglas M. Photiadis,and 1. A. Bucaro (Naval Res. 5aSA10. Wave packet synthesisvia the wavelet transform. David Lab., Washington,DC 20375-5350) M. Drumheller, David H. Hughes, Brian O'Connor, and Charles F. Ganmond (Acoust.Div. Naval Res.Lab., Washington,DC 20375-5350) Numericalexperiments have been carriedout to studythe broadband structuralacoustics of an aircraftlikeshell under point excitation.The A wavelet transformis usedto synthesizedistinct contributions from dominant mechanisms that lead to the enhancement of interior acoustic the monostaticform function for a randomlyribbed, complex end-capped, modesof this finite shellare examined.To thisend, the shellresponse is finitecylindrical shell. In orderto achievesatisfactory wave packets,as studiedfor boththe fluid-loadedand in oacuo cases.A rigid shell calcu- measuredby their cross-correlationwith the originalimpulse response, lationwas alsoperformed to determinethe importanceof the wall com- two wavelet transformsare used,a temporalwavelet transformand a plianceon the interioracoustics. It wasfound that the low-frequencyshell spectralwavelet transform. This is in contrastto synthesizingwave packets responseis not dependenton the free-wavedispersions, and is drivenby from the Wignet distributionwhere just one two-dimensionalsurface was the interiorvolume acoustic modes. At higherfrequencies, the shell and necessary.However, interference terms between components in theWignet fluid are coupledat shell wave numbersdetermined by the free-wave distribution,which is quadraticin the underlyingsignal, are absentin the dispersions.In general,the shelland fluid couple at primarilyone circum- linear wavelel fransform.This allows for a more facile symhesisof the ferential mode. acousticexcitations. The interferenceterms in theWignet distribution can sometimesfall at pointsin the time-frequencyplane where a signalcom- ponentexists, making it difficult to synthesizethat componentwithout 10:30 corruptioncaused by the presenceof othercompounds in the form func- 5aSAS. Implementation of infinite elements in adaptive multilevel tion. substructuringfor structural acousticcalculations. Paul D. DSouza andJeffrey K. Bennighof(Dept. of AerospaceEng. and Eng. Mech., 11:15 Univ. of Texasat Austin,Austin, TX 78712-10S5) 5aSAI1. Apparent anomaliesin the forced vibration of a damped A procedureis presentedfor incorporatinginfinite element modeling of beam. MauroPierucei and Wensen Liu (Groupin Appl.Mech., College the external acousticmedium in structuralacoustic calculations using of Eng.,San Diego State Univ., San Diego, CA 92182-1311) adaptive multficvel substructuring.The coupled structure-fluid system is modeledusing finite elementsfor the structure,and for the acousticfluid An infinitelylong Bernoulli beam with lineardamping is actedupon by externalto thestructure and within a circumscribingprolate spheroid, and a localizedforce given by •5(x)u(t)e•. The resultsare thenobtained in infiniteelements external to the prolatespheroid, following the formula- wave-numberspace and the inversionis carriedout by usingan FFT tion of Burnett(1994). The adaptivemultilevel substructuring approach algorithm.Several interesting and not previouslyreported results will be transformsthe structure model from the original finite element one in terms presented.The solutionin the transformdomain is composedof four of nodaldisplacements, to a muchmore efficient one in termsof responses terms:two transient terms with wave numbers equal to k •/• andk andtwo in approximatesubstructure vibration modes, which are selectivelyin- steady-stateterms; one propagates energy into the far field while the other cludedin the model to optimizeaccuracy per degreeof freedom.This is a decayinglocalized disturbance. The disturbancecreated by thisnear approachis also usedon the finite elementportion of the acousticfluid fieldsloshes energy back and forth near the location of theforcing func- model,and results in a highlevel of modelreduction there. Transformation tion.The apparentbackward traveling wave which is presentin thesteady- of the infiniteelement portion of the acousticfluid model is notpractical statecondition is notdue to the localizedcontinuous reflection of energy 3340 J. Acoust.Soc. Am., Vol. 96, No.5, Pt. 2, November1994 128thMeeting: Acoustical Society of Amedca 3340 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp fromthe distributed damping but is dueto therequirement that the beam We describethe vibrationof a submergedelastic solid within a statis- vibrationhas to havecontinuity of displacementand slope.The force ticalenergy analysis (SEA) framework. We discussthe modal structure of responsiblefor thecontinuity of theslope is Ihe culpritfor thisapparent a submergedelastic solid, and contrast it to thatassumed in traditionalSEA phenomena.If theforcing function is costat, thesteady-state solution can analyses.In particular,submerged solids have higher modal density than be obtainedwithin 20 periods,while if the functionsin tat is used,then the their in vacuocounterparts, much higher levels of (frequencydependent) steady-statesolution cannot be obtained until more than 106 periods. damping,and possiblystrong coupling belween the fluid and solid. Fur- ther, modesof submergedstructures do not form a completeset, and the 11:30 energyof oscillationin a fluid/solidmode is often irretrievable,indepen- 5aSAI2. SEA with exterior fluid loading:An open channeling. Paul dentof thecoupling in thesystem. These results pinpoint the shortcomings E. Barbone(Depl. of Aerospaceand Mech. Eng., 110 Cummington St., of SEA in addressingexterior fluid loading.We closeby identifyingre- BostonUniv., Boston,MA 02215) and D. G. Crighton (Univ. of searchdirections for the advancementof SEA towardincorporating exte- Cambridge,Cambridge CB3 9EW, UK) riorfluid loading. [Work supported by ONR.] SpecialNote: Postersto be presentedin Session5pSP will be on displayin BallroomA from 8:00 a.m. to 5:00 p.m. FRIDAY MORNING, 2 DECEMBER 1994 WEDGWOOD ROOM, 9:00 TO 11:35 A.M. Session 5aSP SpeechCommunication: Models of SpeechProduction Ingo R. Titze, Chair SpeechPathology and Audiology,University of Iowa, Iowa City, Iowa 52242-1012 Chair's Introductions9:00 ContributedPapers 9:05 Acoust.Soc. Am. 60, 1366-1380(1976)]. Both of thesepapers are based on small-amplitudevibrations where linearization is assumedto be valid, 5aSP1. Characterization of noise during glottal vibration: allowingnormal modes and naturalfrequencies to be calculated.Although Measurementsperformed on a mechanicalmodel. B. Y. Reis?C. vocalfold tissuesare knownto be nearlyincompressible, the flint analytic H. Coker,and R. A. Kubli (AT&T Bell Labs.,Murray Hill, NJ 07974) expressionfor the normalmodes of vocal fold tissueswere basedon the Speechsynthesis and coding schemes commonly incorporate a random assumptionof completecompressibility. The presentstudy shows how the noisecomponent during voicing. it is hardto isolatethis noisein recorded analyticnormal modes deform and how the naturalfrequencies of oscil- speechbecause of the inaccuracyof characterizinga modulaledrandom lation shift as the vocal fold tissuesare graduallychanged from being processfrom a few nonidenticalperiods with a strongperiodic component. strictlycompressible to absolutelyincompressible, leaving all otherfactors Direct measurementon humansposes many clinical difficulties.Compu- constant.[This research was supported by GrantNo. P60DC00976 from tationalhydrodynamic modeling is difficult,and reliablemodeling of tur- the NationalInstitute on Deafnessand OtherCommunication Disorders.] bulenceis an unsolvedproblem. Here, direct steady-statemeasurements are made on a detailed, life-size mechanical model. A molded rubber 9:35 modelof thevocal cords is drivensynchronously with the samplingclock so that preciserepetitions of pitch periodsare generated.The random 5aSP3. A Navier-Stokes solutionof laryngeal flow during vocal fold componentof the recordingis isolatedby subtractingaway the periodic oscillations.Fariborz Alipour and lngo Titze (Dept.of SpeechPathol. component(obtained by ensembleaveraging across 1000 pitchperiods). andAudiol. and the Natl. Ctr. for Voiceand Speech,Univ. of Iowa, [owa The noisepower and its spectrumal eachpoint in Ihe pitch periodare City, [A 52242-1012) estimatedby ensembleaveraging the autocorrelationsof the noise.The Dynamicmodeling of vocal fold tissuemovement and laryngealair- noiseresults are well explainedin termsof the directlymeasured trans- flow was combinedin a computersimulations for the purposeof voice glottalpressure and glottal area. In high-passedhuman speech, bursts of production.A finite-elementmodel was usedfor the solutionof tissue noiseappear to overlapthe closed-glollisinterval. To explainthis, it is mechanics and a finite volume method was used in the solution of Naylet- necessaryto includetransit time for glottalair burststo reachan obstruc- tion 2-3 cm downstream.a}Also a studentat MFF. Stokesequations for theairflow. A so-called"shadow method" simulated the glottalconstriction in the flow modelto avoidthe complexityof grid movement.The two-dimensionalflow equationswere solved in an iterative 9:20 manneruntil the given transglottalpressure was approximated.The flow .solutionwas then usedin the estimationof the aerodynamicforces on the 5aSP2. The normal modes of incompressible vocal fold t'ssues. tissue,required in the finite elementsolution of tissuemovement. The DavidA. Berryand Ingo R. Titze (Natl. Ctr.for Voiceand Speech, Dept. resultsindicate that glottal velocity profilesare parabolic,with maximum of SpeechPathol. and Audiol., Univ. of Iowa,Iowa City, IA 52242) velocity in the exiting jet reaching35 m/s. The time-varyingReynolds Muchof the theoreticalgroundwork for treatingvocal fold vibrations numberin the glottiscan reachup to 1500 at a lungpressure of 8 cm water. as viscoelasticwaves in a continuumcan be foundin earlierpublications The jet velocitywaveform is similarto thatof an excisedlarynx and the [Titze andStrong, J. Acoust.Soc. Am. 57, 736-744 (1975) andTitze, J. pressureprofiles are similarto thoseof steadyflows in physicalmodels. 3341 J. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128th Meeting:Acoustical Society of America 3341 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp Also,the displacement of theinferior portion of glottisshows previously significantmodifications of the vocaltract. It is suggestedthat the larynx describedphase differences with the superior portions. [Work supported by is responsiblefor theproduction of themultiple tones in low chanters.Low NIDCD Grant No. DC00831-03.] and high chantersappear to use differentstrategies to achievethe same multiphoniceffect. Our findingscorroborate earlier findings by Smith, Stevens,and Tomlinson [J. Acoust.Soc. Am. 41, 1262-1264(1967)] for 9:50 low chanters. 5aSP4. Stress-strainresponse of the human vocal ligamentand its effect on F 0 control. Ingo R. Titze, Young B. Min, and Fariborz 10:50 Alipour-Haghighi(Natl. Ctr. for Voiceand Speech and Dept. of Speech Pathol.and Audiol., Univ. of Iowa, Iowa City, IA 52242) 5aSP7. Three-dimensional tongue shapes of sibilant fricatives. ShrikanthNarayanan, Abeer Alwan (Dept.of Elec.Eng., 66-147E Eng. The longitudinalelastic properties of the humanvocal ligamentwere IV, UCLA, 405 HilgardAve., Los Angeles,CA 90024), and Kate quantifiedby stress-strainmeasurements and by modelingthe response Haker (Cedars-SinaiMed. Ctr., LOsAngeles, CA 90048) mathematically.Human ligaments were obtained from surgery and autopsy cases.They weredissected, mounted, and stretched with a dual-servoer- In this study,3-D tongueshapes reconstructed from MR imagesob- gometerto measureforce versus elongation and to convertthe results into tainedduring sustained production of thefricatives/s,J',z,3/by four speak- stressand strain.To calculatea longitudinalYoung's modulus, the stress- ers are analyzed.Images were collectedin the coronal,axial, andsagittal straincurves were fittedwith polynomialand exponentialfunctions and planesusing a GE SIGNA 1.5 T machinewith imageslice thickness of 3 differentiated.Young's modulus was separately defined in thelow andhigh mm andno interscanspacing. Results show that the tongue body for/s/and strainregions. The meanYoung's modulus for the low strainregion was /z/is significantlylowered behind the constrictionwith respectto the tip 33.1-+10.4 kPa. In the high strain region,A and B parametersfor an and back of the tongue;the tonguebody has flat or slightlyconvex con- exponentialfit in the highstrain portion were 1.4-+1.0 and 9.6-+1.2 kPa, toursin the constrictionregion that become significantly concave behind respectively.The stress-strainand Young'smodulus curves showed the the constriction.The degreeof concavityis speakerdependent, and de- typicalhysteresis and nonlinearityseen previously in other vocal fold creasingconcavity is observedas the posteriorpharyngeal wall is ap- tissues(muscle and mucosa),but the nonlinearitywas mostprofound for proached.For/J'/and/3/, the tonguebody rises slightly along its midline thevocal ligament. The effectof theseresults on F 0 controlwill be dis- beforeit startssloping towards its posteriorend; the tongueshape behind cussed.[Work supported by NIDCD GrantNo. DC00976.] the constrictionis convex(two subjects)or flat (two subjects)and gradu- ally turnsconcave towards the posterior region. The "grooving"effect in 10:05 /s,z/contributesto a relativelyabrupt increase in the areafunction behind the constrictionwhen compared to/•,3/. Similarly,raising of the tongue 5aSPS. A dynamicalsystems model representationof the F0 backin/s,z/results in smallerareas near the velum when compared to/•,3/. fluctuationof voice. Yuki Kakita and Hitoshi Okamoto (Dept. of Theacoustic significance of these articulatory shapes are discussed. [Work Electron.,Kanazawa Inst. Tech. (KIT), 7-10hgigaoka, Nonoichi-Machi, supportedin partby NSF.] Kanazawa-Minami,921 Japan) This paperproposes a simplemodel of generatingtime seriesof F0 (fundamentalfrequency) fluctuation of voice from the viewpointof the dynamicalsystems generating the irregularity. The data examined were the 11:05 F0 fluctuationfor two kinds of voice, the normal and the pathological 5aSP8. Tongue structural model: Integrating MRI data and (perceivedas "rough"). The time seriesof F0 were obtainedfrom the anatomical structure into a finite element model of the tongue. speechwaveform of sustainedutterances. The voice samplesanalyzed Chao-MinWu (Biomed.Eng. Ctr., Ohio StateUniv., Columbus,OH were for 20 normal(for five male and threefemale subjects) and 39 43210 and ATR Human Inf. Process.Res. Labs., Kyoto, Japan)and pathological(rough) (for sixteenmale and one female subjects). By ex- ReinerWilhelms-Tricarico (MIT, Cambridge,MA 02139) aminingthe time seriesand the pseudo-phase-portraits,a simple two- dimensionalmathematical model generating the time seriesof fluctuation The goalof thisresearch is to obtaina three-dimensional(3-D) tongue is proposedby combining the characteristics of the H6non map ("folding" structuralmodel as a referenceplacement for dynamicsimulations of the operation)and the Delayed logistic map ("twisting" operation). Using the tongueduring speech articulation. The tonguestructural model adapted to model,basic aspects of the fluctuationsas well as of the pseudo-phase- eachindividual's anatomy will be developedby integratingtongue shape portraitsare successfullydescribed with a singlecontrol parameter. The informationfrom MRI scansand anatomicaldrawings to form an anatomi- modelsimulation also suggests that a resultantintermittent type of fluc- cal model. The data structure of this model will be a finite element mesh. tuationmanifests a chaoticbehavior which is actuallyobserved in a patho- Interactiveprograms written in MATLABare developedto (i) manually logicalrough voice. The transitionof fluctuationfrom the normalvoice to extracttissue boundary information from MRI dataof the tongueand other the pathologicalvoice is simulatedby this model. oral structure,(ii) combinethis informationwith the anatomicaldrawings of crosssections of the humantongue to form an anatomicalmodel, and 10:20-10:35 Break (iii) fit a basicfinite element model (topological model) to the anatomical modelto form the tonguestructural model for a samplevowel gestureof eachsubject. Both processes (ii) and(iii) will be achievedby a methodof 10:35 3-D nonuniformgeometrical mapping using a generalizedthin-plate spline 5aSP6. Multiphonic vocalizations:A multifactor analysis of Tibetan mapping.Two tonguestructural models (one for a Caucasiannative Ameri- monk chanting. Claudio F. Milsrein and Thomas Shipp (Dept. of can male and anotherfor an Asian native Japanesemale) will be built, Speechand Hear. Sci., Univ.of Arizona,Bldg. 71, Tucson,AZ 85721) usingMRI data obtainedduring a sustainedvowel production.[Work sup- portedin part by a NSF grantto Dr. O. Fujimura.] Multiphonic chantingrefers to highly specializedvocal techniques wherein one personis able to sing two or more tones simultaneously. Tibetan chantingis one of thesetechniques. Five Tibetan monkswere 11:20 studied(two low chantersand threehigh chanters).Digital recordings, 5aSP9. Determining vocal tract shape with small section length EGG, airflow giottograms,oral fiberopticlaryngoscopy, and perceptual given only a few formants. T. V. Ananthapadmanabha(Voice and datawere analyzed.Spectra from bothtypes of chanterspresented a dis- SpeechSyst., 53, "Girinivas,"Temple St., Malleswaram,Bangalore 560 play of extremelywell definedF• and F 2 tunedto specificharmonics 003, India) (harmonics5 and 9 for low chantersand harmonics2 and 4 for high chanters).Low chantersshowed unusual activity at thevocal fold leveland Vocaltract shape made up of cylindricalsections of equallength can be were able to maintainthe multiphonicquality and formanttuning despite determinedgiven the formantdata of vowel sounds;the numberof sections 3342 d. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128th Meeting:Acoustical Society of America 3342 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp equalstwice the numberof formants.For an adultmale speaker, use of This constraintgives unrealistic locations for the upperformants. One four formants,results in a largesection length of 2.125 cm. !f section methodfor predictingthe upperformants would be to use thoseof a lengthof 0.5cm is desired, 17 formants have to be specified which appears uniformtube of samelength as that of thevocal tract. For a desiredsection impractical.A methodfor obtainingvocal tractshape with smallsection length(say 0.5 cm),the required formants (say, 17) canbe specifiedby lengths,given only a few lower formants(up to fourthor fifth) is pre- usingthe given lower formants (say, four) and predicted upper formants sented.For vocal tract of M sections,only the lower M/2 fermentsare (say,from 5 to 17). Validationof the methodusing x-ray data and simu- independentand upperferments are constrainedby the lower ferments. lated vocal tract shapesis presented. FRIDAY MORNING, 2 DECEMBER 1994 BALLROOM B, 8:00 A.M. TO 12:15 P.M. Session 5aUW Underwater Acoustics:Propagation I Daniel Wurmser, Chair Naval ResearchLaboratory, Code 7144, Washington,DC 20375-5350 ContributedPapers 8:00 Considera stronglystratified ocean with randomnessfor which nu- mericalcomputation of averagecomplex pressure with two-waypropaga- 5aUWI. A new imrabolie equation for range-dependentsound tion is to be made.Let depthdependence be piecewisecontinuously dif- speeds.Roger Dashen (Phys.Dept., Univ. of California,San Diego, La ferenttableand sedimentbe modeledby a fluid bottom.Within a fixed Jolla,CA 92037}, DanielWurmser, and Gregory erris (NavalRes. Lab., Washington,DC 20375-5350) rangeinterval, model uncertainty by an ensembledependence upon some parameterin a continuouslydifferenttable way, and the range dependence A new parabolicequation for ronge-dependentsound speeds has been to be piecewiseconstant over independent intervals. For a singlefrequency developedby modifyinga procedureborrowed from quantummechanics. sourceat a knowndepth, analysis for one elementof the ensemblepro- The forwardand backward propagating solutions are alecoupledorder by ceedsvia the Helmholtzequation in radialsymmetry and satisfies an out- orderby repeatedapplications of the Foldy-Wouthuysentransformation. wardradiation condition at largerange. A previouslydeveloped modifica- The resultincludes energy-conserving terms which are proportionalto the tion for finite length range intervalsin finite depth of the Kohler- secondrange derivative of the soundspeed squared. Physically, the tech- Papanicolaoucoupled mode equations in the forward scattering niquehas identified the terms responsible for heretoforeanomalous refrac- approximationJR. M. Oba,Acoust. Lett. 16, 56-61 (1992)]computes the tive effectswhich accumulateduring propagation as a resultof rapidos- transmissionloss and phase for the averagesolutions for one-waypropa- cillations between the forward and backward propagatingsolutions. gation.This paperpresents a reformulationof this methodto two-way Moreover,this phenomenondoes not resultin permanentenergy transfer propagationof averagesolutions. This analysiswill alsoshow the devel- betweenthe two types of solutions.['Work supported by ONR.] opmentand computation of averagedscattering type operators. [Work sup- portedby NavalResearch Laboratory and ONR.] 8:15 5aUW2. Range-stepping algorithm for the Helmholtz equation. DaleinK. Dacol (Naval Res.Lab., Washingion,DC 20375-5350) 8:45 Theusual range-stepping algorithms usedto obtain •napproximate 5aUW4. Nonparabolic marching algorithm for sound field solutionto the Helmholtzequation are basedon the parabolicapproxima- calculationin the inhomogeneousocean waveguide. A. Voronovich tionand restricted to theforward propagating component of thesolution. A (NOAA/ERL/EnvironmentalTechnol. Lab., 325 Broadway,Boulder, CO completesolution of the Helmholtzequation in an inhomogeneousme- 803O3) dium mustalso include backpropagating waves, that is, wavesscattered towardsthe sourceby inhomogeneities.The inclusionof sucheffects in a A new algorithmis proposedfor calculatingsound field in the inho- numericallyfeasible full-wave approach to acousticpropagation is a prob- mogeneousocean waveguide. It doesnot involve parabolic approximation lem of continualinterest in oceanacoustics. This problemhas been studied and at leastfor 2D inhomogeneitiescan be consideredas exact.On the usingthe methodof coupledamplitudes. Theoretical developments on the otherhand, it is "marching"and can be as easily implementedas a pare- applicationof thistechnique to oceanacoustics will bediscussed as well as belie equation.For inhomogeneitywith final horizontalexlent, the algo- numericalapplications to theASA range-dependentbenchmark problems. rithm calculates,in particular,the scatteringmatrix for acousticmodes Numericalapplication of this methodinvolves a fourfoldincrease in the interactingwith inhomogeneity.It is significantthat the approach is ableto numberof arithmeticoperations as compared with thatrequired for solving the sameproblem using a PE approach.However, one does get the back- calculatenot only the acoustic field itself, but propagation times of differ- scatteredfield andone not doeshave to approximatesquare roots of dif- ent modesas well. The casesof unevenboundary and mediawith losses ferentialoperators as one mustdo in the PE approach.Since an elliptic can be also dealt with. Thus the algorithmis able to providean exact equationis beingsolved one encountersnumerical instabilities; how to solutionof the Helmholtz equationwith 2D inhomoganeitiesboth for deal with them will be discussed. shallow-and deep-watersituations. The algorithmcan be easilygeneral- ized for the caseof the movingmedia and/or density variations. The cor- respondingcode dace not requiregreat computer memory or speedand can 8:30 be performedon a conventionalPC. Numericalsimulations of sound 5aUW3. A numerical method for random two-way propagationin propagationthrough strong inhomogeneity related to subpolarfront will be the Helmholtzequation. RogerM. Oba (Naval Res. Lab., Stcnnis presented.Two typesof modeinteraction appearing for two-channelsitu- SpaceCenter, MS 39529-5004} ationswill be discussed.[Work supported by ONR.] 3343 J. Acoust.Sec. Am., Vol. 96, No. 5, Pt. 2, November1994 128th Meeting:Acoustical Society of America 3343 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 9:00 9:45 5aUWS. Comparing the performanceof split-stepalgorithms for 5aUWS. Convergenceproperties of wide-angletechniques. David coastal acousticsproblems. David B. King, Stanley A. Chin-Bing Yevick (Dept.of ElectricalEng., Queen's Univ., Kingston, ON K7L 3N6, (NavalRes. Lab., StennisSpace Center, MS 39529), and MichaelD. Canada) Collins (NavalRes. Lab., Washington, DC 20375) Therelative accuracy of varioushigh-angle propagation methods were The split-stepFourier algorithm [R. H. Hardinand ED. TappeR, examinedfor the caseof a rapidlyexpanding point source. It wasestab- SIAM Rev.15, 423 (1973); S. M. Flatt6and F. D. TappeR,J. Acoust. Sec. lishedthat the removalof evanescentmodes in wide-anglecalculations Am. 58, 1151-1159(1975)] has been an importanttechnique for solving through,e.g., hybridFourier/Lanczos or Fourier/Pad•algorithms [J. range-dependentocean acousticsproblems for more than two decades. Acoust.Soc. Am. 96, 396 (1994)], greatly improves the numerical predic- Since this algorithmis restrictedto leading-orderasymptotics, parabolic tionsof suchtechniques. A/tematively, procedures in whichthe imaginary equationsolutions based on finite-differencealgorithms have been devel- partof theThomson-Chapman propagation operator is appliedafter each oped for handlingeffects that require higher-orderasymptotics, such as propagationstep may also be employedto increasethe rate of convergence wide propagationangles, extensive bottom interaction,and elastic and of standardunitary methods. Further, it wasfound that for moderatestep poreelasticwaves. The split-stepFourier algorithm has remained in wide- lengthsand highlydivergent fields the errorsimplicit in rationalapproxi- spreaduse despite the improved accuracyand capability of finite- mationsto the square-rootoperator are comparableto •hoseassociated differencesolutions. The split-stepPad6 algorithm [M.D. Collins,J. with analogousapproximations to the full propagatoras well as with Che- Acoust.Sec. Am. 93, 1736-1742 (1993); M.D. Collins,J. Acoust.See. byszevexpansions of theexponent of thepropagation operator with degree Am. 96, 382-385 (1994)],which includes higher-order asymptotics, is abouttwice that of theequivalent Pad• method. Finally, a heuristicbut ordersof magnitudefaster than standard finite-difference solutions. Results usefulrelationship betwe.•n the rate of convergenceof a givenLanczos will be presentedfor representativetest problemsto illustratethat the techniqueand the Taylorseries expansion of the underlyingpropagation split-stepPad6 algorithm is alsomore efficient than the split-step Fourier operatoris outlined. solutionfor the coastalacoustics problems that are currentlyof interest. 10:00-10:15 Break 9:15 10:IS 5aUW6. Direct solutionof the acousticwave equationin underwater environments with attenuation using the finite difference method. 5atlW9. High-frequencypropagation in a turbulent flow. David M. R. A. Zingarelli (Naval Res. Lab., Acoust.Simulation Sect., Stennis Farmer,Daniela Di Iorio, andWard Cartier (Inst.of OceanSci., 9860 W. SpaceCenter, MS 39529) SaanichRd., Sidney,BC VSL 4B2, Canada) A finitedifference solution to the acousticwave equation for real pres- As part of the new ONR-initiativein moderate-to-high-frequency surefields which incorporates sediment attenuation has been implemented. acoustics,a pilot experiment will be carriedout in a shallowtidally forced The differencingmethod is a centeredspace/centered time solutionof the channelin September1994 to compareacoustic variability with direct undampedwave equation, with absorbingboundaries simulated by an off- measurementsof turbulentvelocity and sound-speedfluctuations. The set space/forwardtime solutionof the radiationcondition equation. This acousticconfiguration will consistof a lineararray of four sourceson one algorithmexecutes efficiently on SIMD and MIMD supercomputers,and side,and four receiverson the other(./=67.5 kI-rz,L•700 m), together givesan acceptablesolution to theASA idealwedge benchmark problem. with a singlesource and receiver for reciprocaltransmission. Separation of Stability,memory, and executiontime considerationswill be presented. reciprocaltransmission from receptionof the otherfour sourcesallows a Two basicattenuation methods, an ad hoc absorptionterm and a Lax repetitionrate for all sourcesof 5 Hz. The spatialfilter will be appliedto solutionof the dampedwave equation,along with severaldifferencing theacoustic data so as to focusthe measurement on thecentral portion of schemesfor each,were implemented.Results and runtimesfor CW and thechannel, at whichlocation a mooredturbulence sensor (R. Lueck)will time domainbenchmarks and otherproblems incorporating bottom attenu- be deployedat the samedepth as the acousticpath. Supplementary mea- ationwill be presentedand discussed. [Work supported by ONR.] surementswill be acquiredwith a multiplefrequency backscatter sonar, mooredcurrent meters, and pressure gauges, and a neutrallybuoyant float to measurethe larger scaleturbulent motions (E. D'Asaro, APL-UW and 9:30 D. Veenstra,IOS). The experimentalwork will be discussedin thecontext of prior studiesof forwardscattering from turbulenceand preliminary 5aUW7. A model for wave propagationin an inhomogeneouselastic resultswill be presented. medium. RaymondJ. Nagem (Dept.of Aerospaceand Mech. Eng., BostonUniv., 110 CummingtonSt., Boston,MA 02215), Ding Lee, 10:30 and Tien-ChayChen (Naval UnderseaWarfare Ctr., New London,CT O6320) 5aLIWI0. Acousticscintillation and random focusingeffects in the ocean. JohnR. Potter (MarinePhys. Lab., Scripps Inst. of Oceanogr.,La A perturbationmethod is usedto deriveequations for wavepropaga- Jolla, CA 92093-0238) tionin an inhomogeneouselastic medium. The formulationis threedimen- sional, and is written explicitly in cylindricalcoordinates so that it can Small-scaleoceanographic variability becomes increasingly relevam to includeproperty variations in the depth,range, and azimuthdirections. A acousticpropagation as the frequencyof interestexceeds a few kHz. The factorizationis usedto convertthe equationsinto an operatorform which intensityeffects are generally unspectacular at very close or distantranges; distinguishesoutgoing waves from incoming waves. This factorlzation little a•attorlnghaa yet occurred in thenear flold and atochaati½ limits apply removesthe requirement for a far-fieldboundary condition. For large-scale in the far field.At intermediateranges random focusing can greatly en- numericalproblems, the factorizationproduces a tremendousreduction in hancethe intensityin smallvolumetric regions. These predicted high- computationtime andin memoryrequirements. The elasticequations are intensity"ribbons" result from an accrual of multipleforward scattering of written in a way that is directly analogousto previouswork in ocean individualwavefronts and appear in additionto multipatheffects. An ex- acoustics.With appropriatefluid-elastic interface conditions, the elastic perimentwas performed in theeastern Mediterranean during 1986 using andacoustic equations may be usedto studythe fluid-elasticinteractions 3.6-kHzpulses transmitted over ranges of 11-23 km to investigatethis whichare important in shallow-waterenvironments, especially the propa- effect.Observations were made over vertical and horizontal apertures of gationof shearwaves in the oceanbottom. In this paper,the theoretical 200-250 m and4-4.5 kin, respectively.The experimentis describedand developmentof the elasticequations are presentedand their meritsand the randomfocusing is confirmed.The acousticsignals traveling along applicationsare discussed. [This work was jointly supported by theU.S. individualray pathsare observed to developrandomly focussed regions Office of Naval Researchand the U.S. Naval UnderseaWarfare Center.] 6-18 dBabove normal levels over regions some I kmlong and 20 m deep. 3344 d. Acoust.Soc. Am., Vol. 96, No.5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3344 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp The strengthand size of theseanomalies are consistentwith predictions 11:30 from multiplescattering theory. Underslanding these features creates the possibilityof inversionfor a statisticaldescription of the small-scale 5aUW14. Site selection for a long-term acoustic study of the oceanographyin additionto permittingconstructive tactical use and im- temporal variability in a shallow-water environment. Ted Farrell, provedquantitative estimates of systemperformance. [Work supported by Rigo Torres,Cola Atkinson,and Grcg Duckworth (BBN Syst. and ONR.] Technol.,1300 N. 17lb St., Ste. 1200,Arlington, VA 22209) A siteselection study was performed to determinethe best location for an environmental-acousticmeasurement system to be deployedfor two 10:45 yearsin shallowwater. The studysearched for continentalUnited States (CONUS)locations where the environmentalparameters are sufficiently 5aUWII. Effect of random volume and surface fluctuations on variable such that, over time, the acousticenvironment at these locations propagationin shallow water, Terry E. Ewart and Daniel Rouseff will be similarto the environmentsfound at multiplelittoral regionsof (Appl.Phys. Lab., Univ. of Washington,Seattle, WA 98105) inlerestoutside of CONUS. Shippingdensities, sound-speed profiles, wind The potentialdifficulties associated with modelingacoustic propaga- speed,rainfall, bathymetry, and sedimentcharacteristics were investigated tion in shallow-waterenvironments are well documented.Larger scale usinga MATLAB© basedgeographic information system. As part of the deterministic features combine with random fluctuations in the water col- investigation,measures of variabilitywere definedfor eachenvironmental umn,sediment, sea surface, and bottomto producean extremelycompli- variable.in addition,automatic classification of soundvelocity profiles catedpropagation regime. The extentto whicheach of thesefealures needs wasimplemented on morethan 44 000 measuredprofiles from the areasof to be includedin realisticpropagation models remains to be quantified. interest.The resultsof the study show that severalCONUS areashave Towardsthis end, resultsfrom a seriesof detailedsimulations generated enoughenvironmental variability to satisfythe requirements of a long-term usingthe parabolic equation (PE) method are presented. Beginning with a measurementprogram. The systemdeveloped for this effortsignificantly deterministicdownward refracting sound-speed profile and a knownslop- reducedthe time requiredto analyzeand visualize large amounts of envi- ingbottom, realizations of therandom features are sequentially added to ronmentaldata. The systemalso provides a meansto coupleenvironmental the simulation.Pierson-Moskowitz surface waves, power-lawbottom datainto various acoustic models. [Work sponsored by ONR.] roughness,and representativebottom absorptionare used to model the medium.The individualand cumulalive effects of thesescaltering mecha- nisms on the acoustic wavefront are evaluated. Successive interactions 11:,15 with a randombottom are studied.The resultsare quantifiedby usinga 5aUWlS, Coregistration of received signals with bathymetry using modaldecomposition and also by examiningthe local arrival angleof AR'HST, VincenlH. Lupienand J. RobertFricke (Dept. of OceanEng., energyas a functionof depth.[Work supported by ONR.] MIT, Rm. 5-435, 77 MassachusettsAve., Cambridge,MA 02139) As part of the ARSRP, a softwarepackage called AcousticalRay- 11:00 TracingInsonification Software (AaT{ST) was developedwhich performs the coregislrationof receivedsignals to areasof the seafloorfor direct 5aUW12. Pulse propagationin a range-dependentturbulent ocean, paths.The transmittingand receivingarray beampatternsare projected W. R. Chang,S. H. Doog, and J. H. Tamg (Dept. of Commun.Eng., ontothe actual seafloor by ray-tracingto yield two insonificationpatterns. Chiao-TungUniv., Hsin-Chu,Taiwan) The (x,y) loci of ray contactswith the seafloorare then triangulatedand shadow-zoneprocessed so that the interiorof each triangleis insidethe In thisresearch, an acousticpulse propagating in a turbulentocean with illuminatedregion. Using a bivariateinterpolator over eachtriangle of the slightly range-dependentvertical sound-speedprofile is investigated.A insonificationpatterns, an intersectionpattern is generatedon a rectangular numericalapproach called the split-stepmethod, based on the parabolic grid, yieldingamong other parameters:two-way travel times,TL, beam- equation,is usedto simulateeach frequency component of the pulseto patternvalues, and grazingangles. Only the pointswhich lie in the illu- propagatethrough the ocean.A randomphase screen is generatedto in- minatedzones of both the receiverand transmitterare kept. By using cludethe effects of randomfluctuation of sound-speedprofile in eachstep. anotherbivariate interpolator over eachpatch of the intersectionpattern, The averageacoustic pulse profile and root-mean-square pulse width are pairsof time contoursare generatedand for eachpatch intersected by a evaluatedfor differentfluctuation strengths and scalelengths of turbu- contour;the fractionalarea lying insidethe time windowis calculated.The lence.Some results are comparedwith thosecomputed by theoreticalap- final stepin the coregistrafionis to selectonly thosepatches which are proach.It is foundthat in eachrealization the pulseechoes, due to the mostloudly insonified for eachtime window. The patchesdo nothave to multipathpropagation, are changedin arrival times, pulse shapes,and be adjacentand the amplitude criteria are user-specified. [Work supported numbersbecause of the randomfluctuation of the sound-speedprofile. The by ONR.] broadeningof the pulsewidth is variedfor differenldepths of the receiving position.An initial Gaussian-shapedpulse is considered.For the simula- tions,a Gaussian-beamsource is usedinstead of a point source.Here, the 12:00 sound-speedprofile is assumedto be changeduniformly in the rangedi- rection. 5aUW16. Diffraction of acoustical waves by spattally localized inhomogeneitiesin oceanicwaveguides. SergeyM. Gorsky,Vitaly A. Zverev,and AlexanderI. Khil'ko (Inst. of Appl. Phys.of Russian Academyof Sci., Hydrophys.Dept., 46 UIjanovaSt., Nizhny Novgorod 11:15 603600, Russia) 5aUWI3. Intensity statisticsof acousticwaves scatteredby internal waves. Roger Dashenand JamesGerber (Univ. of California,San Diego, La Jolla, CA 92093-0319) in oceanicwaveguides has been investigated.The formula for scattering matrixof diffractedwaveguide modes has been obtained using a "short- Intensitycorrelations for oceanacoustic propagation show markedly wave" approximation.The spatial-frequencydiffraction patterns for dif- differentbehavior in the partiallysaturated regime than in the fully satu- ferentlocations of inhomogeneities,sources and receivers,and properties rated regime. In contrastto the known exponentialdecay of temporal both of the spatial-localizedinhomogeneities and the waveguideswere intensitycorrelations in full saturation,partial saturationcorrelations fall investigatednumerically. The possibilitiesof diffractedfields measurement off very slowly.This phenomenonis a consequenceof the peculiartime in naturalDiffractionwaveguides oftheacousticwere investigatedfieldsby spatiallyunder thelocalized conditionsinhomogeneities of physical dependenceof internalwaves, and does not occur in otherphysical situa- modelingin Ihe ultrasonicfrequency region. The significanceof physical tions,such as atmospheric optics. Results of a numericalsimulation which modelingmethods for investigationof diffractionphenomena in oceanwas demonstratethe effectare presented. demonstrated.It was shownthat the efficiencyof diffractedfield observa- 3345 J. Acoust. Soc. Am., Vol. 96, No. 5, Pt. 2, November 1994 128th Meeting: Acoustical Society of America 3345 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp tionscan be increasedusing results of calculationand measurements under backgroundof noiseof randomlydistributed oceanic inhomogeneities. modelconditions. The spatial-temporal filtration by horizontaland vertical Besidesthat, a systematicconcept of the structureof perturbedsignals in arraysand by matchingprocessing of complexpulse illumination signals waveguidesand an analysisof the possibilitiesof its observationsin lay- were discussedas methodsfor isolationof diffractedsignals against the eredwaveguides were developed. FRIDAY AFTERNOON, 2 DECEMBER 1994 PECOS ROOM, 1:00 TO 3:30 P.M. Session5pEA EngineeringAcoustics: Ultrasonic Transducers and Measurements MagneVestrheim, Cochair Departmentof Physics,University of Bergen,Allegt 55, N-5007,Bergen, Norway John Behrens, Cochair AppliedResearch Laboratories, The Universityof Texas,P.O. Box 8029, Austin,Texas 78713-8029 Contributed Papers 1:00 receivingelectronics and cablingare also measuredand included.The resultsare usedto discusseffects on the transittimes for recentprecision 5pEA1. Modified lead titanate with Eu and Mn for high-frequency multibeamultrasonic flowmeters used in the transportof naturalgas, and ultrasonictransducer. E. Suaste,J. Leyb6n,V. H. Salazar (Cinvestav at resolutionand accuracies required in the zero calibrationof suchmeters. I.P.N., Dept. of Electrical Eng., Bioelectron.Section, AV. IPN 2508 [Workperformed in cooperationwith ChristianMichelsen Research, Ber- MexicoD. E), and O. Perez-Mart{nez(Cuba) gen.] The conventionalmaterials, such as PZT ceramics,show a high elec- tromechanicalcoupling factor; however, they must be acoustically 1:30 matchedto tissuein order to facilitate transmissionand receptionover a broadfrequency band. Application of thisceramic in lineararrays entails 5pEA3. A phaseanalysis of an ultrasonicpulse signal for measuring additionalcomplexity. Each elementin an arraymust be subdividedinto travel time. Eunbang Lee and Shigeo Ohtsuki (Precisionand severalsubelements to suppresscoupling unwanted lateral modes. Thus IntelligenceLab., Tokyo Inst. of Technol.,Nagatsuta 4259, Midori-Ku, piezoelectricceramics with large electromechanical anisotropies (the elec- Yokohama227, Japan) tromechanicalcoupling factor for thicknessdilatational vibration K t is muchlarge than that for planarextensional vibration Kp) haverecently A pulsesignal has been utilizedextensively for estimatingtravel time come to be developedfor use as high-frequencyultrasonic transducer in an ultrasonicfield. Travel time canbe measuredby calculatingthe time materials.PbTiO 3 ceramicsmodified with alkalinemetals or rare earth differencebetween transmitted signal and receivedsignal. In a conven- have beenextensively investigated because of their promiseas a piezo- tionalmethod, time resolutionis limited to its pulsewidth. Also, the re- electricalmaterials for high-frequencyand high-temperatureapplications. ceivedsignal has an influenceon the transducercharacteristic and propa- In Pb[(Col/2Wl/e)0.o4Tio.96103ceramics Yamashita et aL reportedthat the gationcharacteristic and is distortedfrom the transmittedsignal. It is not electromechanicalcoupling factor for thicknessdilatational vibration Kt easyto comparebetween two differentsignals for measuringtravel time. A increasingof polingfield but couplingfactor for planarextensional vibra- techniqueto analyzethe pulsesignal by phasefor measuringtravel time is tionKp wasnegligibly small. In (Pb0.s•Ln0.0•)(Ti0.9sMn0.02)ceramics(Ln proposed.This techniquecan be appliedto botha continuous-wavemethod =La, Nd, Sm, andGd) Takeuchiet al. foundthat the Sm ion was excellent and an impulsewave methodfor measuringtravel time. The majorfeature in the substitutionof the Pb ion to make large electromechanicalanisot- is that the fluctuationof signalsdependent on time is displayedin time ropybetween longitudinal and transverse mode vibration. Electromechani- domain,faithfully. Another feature is a methodfor identifyingdifferent cal propertiesof PbTiO3 ceramicsmodified by the partialsubstitution of amplitudesignals, because this techniqueis independentof their ampli- Eu for Pb and Mn for Ti are examined,and the resultsare comparedwith tudesand dc bias.This techniqueis usefuland acceptablefor estimating time information such as travel time. thepartial substitution of Sm andother elements of the lanthanidesgroup. 1:15 1:45 5pEA2. Transit time determination in a one-way ultrasonic 5pEA4. Separation of overlapping reflections for ultrasonic NDE measurement system. Magne Vestrheim, Steinar Vervik, and applications. RichardD. Patton (RaspetFlight Res. Lab., Dept. of MurugendranKanagasundram (Dept. of Phys.,Univ. of Bergen,Al16gt. Mech.Eng., Drawer ME, Miss.State Univ., Mississippi State, MS 39759), 55, N-5007 Bergen,Norway) PatrickC. Marks, andJames Bennett (MississippiState Univ.) Frequencyand time domainanalysis are usedto studythe transittime Sinceindividual layers in a compositematerial return their own reflec- determinationin a one-wayultrasonic measurement system for gasesat tions,it is necessaryfor ultrasonicNDE to separatea receivedsignal into around200 kHz. Effectsof transducers,diffraction, and interfacingto a seriesof reflections.This becomes more complicated when the layers are electronicson pulseforms and transittimes are considered.Comparisons thinnerthan the wavelengthof the ultrasonicsignal used for testing,re- are made with experimentalresults using two transducersmounted in a sulting in overlappingreflections. The Gausslinearization minimization stabilized acoustic chamber where fluctuations can be reduced so as not to methodwas usedto separateoverlapping reflections [J. V. Beck andK. J. affect amplitude and time measurementaccuracies. By utilizing a fitted Arnold,Parameter Estimation in Engineeringand Science(Wiley, New modelfor the transmittingresponses of the transducerstogether with mea- York,1977)]. This algorithm fits a pulseobtained from the pulser receiver suredimpedance data and the assumptionof reciprocity,a usefulmodeling to the measureddata. Amplitude and time delay estimatesare madefor of the signaltransmission through the systemis achieved.The effectsof eachreflection. Multilayer Plexiglas samples with subwavelengththick- 3346 J. Acoust.Soc. Am., Vol. 96, No.5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3346 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp nessesat 1 butnot at 5 MHz werefabricated Io verifythe performance of rejectradio interference, A study was conducted to determinethe optimum thealgorithm. Each sample was tested at 1 andat 5 MHz. Thealgorithm frequencyrange for PD detectionto givemaximum range sensitivity and providedcurve fits for the I-MHz data that were almostidentical to the acousticinterference rejection. This paperpresents transformer noise re- theoreticalresults. The maximumerror was 8% andthe average error was cordedin the field as well as in the laboratorywith externallyand inter- 2%. Eachof the reflectionspredicted by thecurve fits were identified and nally moun•xdtransducers. The data recordsare Fourieranalyzed and verifiedin the5-MHz data. [Work supported by the Mississippi NSF transducerresponse corrected to obtainthe acousticnoise spectra. It is SCoRgrant.] foundthat there is an uppercutoff frequency for transformeracoustic noise whichis around75 kHz andsignals originating from PD havefrequency 2:00 componentsmuch beyond this range. Factors which influence range sen- 5pEAS. Remotesensing of sheetmetal texture in aluminumalloys. sitivity are alsodiscussed. ShermannMin, LawrencePeng, Wei-yang Lu, and Damy Hughes (Sandia 2:45 Natl. Labs., Livermore,CA 94551) 5pEAS. A dual-transducer acoustic time domain correlation Metalforming operations such as deepdrawing, stretching, bending, techniquefor instantaneousblood flow velocity measurement. E.J. hemming,etc. are all significantlyinfluenced by the degreeof crystallo- Kim andS. W. Yoon (Dept.of Phys.,Sung Kyun Kwan Univ.,Suwon graphicanisotropy (texture) present within the workpiece.An effort is 440-746,Republic of Korea) underwayat SandiaNational Laboratories/CA m developtwo noncontact ultrasonicsystems for the measurementof texture in aluminumsheets. A dual-transduceracoustic time domain correlation technique has been Althoughthe efi•:ct of stresswave velocities on elasticanisotropy is well developedto measureinstantaneous blood flow speedand direction.The known,its abilityto predictplastic behavior has yet to be firmlyestab- experimentwas pedormed with an artificialblood flow systemin a water lished.Ultrasonic measurements, which hold the potential for remote,in- tank. The volumetricflow velocityas well as the instantaneousflow ve- processscreening, will be shownto exhibita highdegree of correlation locity at any sitesin aa artificialblood vesselcan be measuredwith the with currenttechniques for measuringtexture, which are off-line, destruc- dual-transducertechnique. In the steadyflow measurements,the volumet- tive,and often inaccurate. Results from an electromagneticacoustic trans- ric flow ratesestimaled from the dual-transducer technique were within the ducer(EMAT) system are used as a baselinecomparison for a moreprom- error rangeof 8% from thoseof the hydrodynamicflow measurements_ ising noncontactlechnique involving the opticalgeneration and detection Evenin the turbulentflow measurements,the instantaneousflow speedand of ultrasound,commonly referred to as laserultrasorties (LU). In addition directioncan be determinedat any sites in the vessel with the dual- to displayingthe level of anisotropy,slowness curves obtained from these transduceracoustic time domaincorrelalion technique. systemssuggest the ability to distinguishbetween different types of tex- ture,as predictedfrom theory. 3:00 2:15 5pEA9. Temperature variation due to ultrasoMe absorption in a proteinsolution. D.O. Shin,E. J. Kim,and S. W. Yoon (Dept.of Phys., 5pEA6. Techniquesand instrumentsfor investigatingthe ultrasonic SungKyan KwanUniv., Suwon 440-746, Republic of Korea) analogsof magnetoopticeffects. VladimirV. Gudkov (Inst. for Metal Phys. of RussianAcademy of Sci., 18 KovalevskayaSt., GSP-170, The temperaturevariation due to ultrasonicabsorption in a protein Ekaterinburg620219, Russia) solutionhas been experimentally investigated. Egg white and 10.6% oval- buminsolution were usedas the samplesof proteinsolutions. For ultra- Magnetoacousticphenomena involving alteration of Ihe polarizationof sonic absorptionthe continuoussound waves of 3.5, 5.0, 7.5, and 10.0 a transversewave (namely,the ultrasonicanalogs of Ihe Faradayand MHz from focusedtransducers were incidentupon the samplesof finite Cotton-Moutoneffects) have been found in yttriumiron garnet [H. Mat- volume,respectively. The temperaturevariation was measured at thefocal thewsand R. C. LeCraw,Phys. Rev. Lett. 8, 397 (1962);B. Luthi,Phys. regionof an ultrasonicbeam in thesample. The measurementsshowed that Lett.3, 285 (1963)].As theellipticity E andthe angle F of rotationof the the temperaturevariation in the eggwhite was muchlarger than that in the polarizationplane are ratherlarge in magneto-orderedmaterials, it was 10.6% ovalbuminsolution. This discrepancymight be due to the differ- possibleto makethe first measurements using distortion of theexponential encesin proteincomposition. decayof the ultrasonicecho pulses in the oscilloscopescreen. After dis- coveringthese effects in metals,a precisetechnique for E andF evaluation 3:15 has beenrequired. A techniquefor measuringF has beensuggested by 5pEA10. Investigation of Lamb waves for sensor applications in Boydand Gavenda [Phys. Rev. 152, 645 0966)]. It is basedon measure- semiconductorprocessing. F. Lcvcnt Degertekin,Victor Honein, and mentsof amplitudeversus magnelic field for two cases:field paralleland ButmsT. Khuri-Yakub (E. L. Ginzion Lab., StanfordUniv., Stanford,CA antiparallelto the wave vector.In the presentpaper both someoriginal 94305) generalizationsof this techniqueas well as a devicewhich enablessimul- taneousmeasurements off andE are reported.In addition,an instrument Consideringthe semiconductorwafers as anisotropicplates, Lamb for visualobservation of the ellipsoidof polarizationand the directionof wavepropagation characteristics are related to variousparameters dynami- the majorellipsoid axis is described. callychanging during processing. Particularly, the effect of wafertempera- ture and thin-filragrowth on phasevelocily of zerothorder Lamb waves 2:30 areanalyzed theoretically. These modes are chosen to enablesingle mode 5pEA7. Optimum frequencyrange for partial dischargedetection in operationinsilicon wafers for frequency-thickness product (fid) lessthan 3 MHz min.The surfaceimpedance approach is usedin theoreticalmod- high-voltage transformers using ultrasonic methods. loseph Kumsingal (Ctr. for Mater.Technol., Univ. of Technol.,P.O. Box 123, elingof propagationin generalmultilayered anisotropic solid structures. Temperature,thin film, and their combinedsensitivily figures are calcu- Broadway,NSW 2007, Australia) latedfor commonlyused structures in semiconductorprocessing. The re- Partialdischarge (PD) erosionof insulationis oneof thedeteriorative sultsare interpretedto obtain optimumultrasonic sensor system param- mechanismsin transformersand high-voltageplants leading to early fail- etersfor certainapplications. For example,in caseof aluminumfilms on ure. Ultrasonicdetection techniques are usedregularly for locationof PDs (100) silicon,antisymmetric mode in (100) directionshows negligible whenelectrical method [IEC Pub.76/IEC 270] usedin routinetests or sensitivityto thin filmsaround f'd=0.8 MHz mm. The samefigure for DGA resultsindicate the presenceof PD. The techniqueuses either exter- silicon oxide film is 1.57 MHz min. In a combined measurement, a tem- nallyor internallymounted ultrasonic !ransducers (J. Unsworth.I. Kurus. peraluresensor usino thesesystem parameters to measurephase velocity ingal,and R. E. James,Proceedings of ICPADM 94, IEEE).Unfortunately ultrasonictechnique requires expert supervision to distinguishPD signal measurement.Practical implementations of the resultsin rapid thermal patternsfrom some typical transformer noise patterns. Moreover, transduc- processingenvironment are also discussed in the paper. [Work supported ers are selectedbased on commercialavailability or for their ability to by SRC.] 3347 J. Acoust. Soc. Am., VoL 96, No. 5, Pt. 2, November 1994 willbeminimally128thaffected Meeting:byAcoustical thin films, Societyenabling of an America isolatedtemperature 3347 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp FRIDAY AFTERNOON, 2 DECEMBER 1994 BALLROOM A, 1:00 TO 5:00 P.M. Session5pSP SpeechCommunication: Voice Quality, Speech Training, Phonetics, and Prosody (Poster Session) Randy L. Diehi, Chair Departmentof Psychology,University of Texasat Austin,300 Mezes,Austin, Texas 78712 ContributedPapers To allowextended viewing time, all posterswill beon displayfrom 8:00 a.m. to 5:00p.m. The session will be heldfrom 1:00 to 5:00 p.m.To allowcontributors anopportunity to seeother posters, contributors of odd-numbered papers will beat theirposters from 1:00 to 3:00 p.m., andcontributors of even-numberedpapers will be at theirposters from 3:00 to 5:00 p.m. 5pSPI. The dimensionalstructure of the lexicon. Lee H. Wurm and speakerswere analyzedand severaltraining targets selected. One conso- DouglasA. Vakoch (Dept.of Psychol.,State Univ. of New York at Stony nant and one vowel contrasteach were selectedfor trainingusing ISTRA, Brook,Stony Brook, NY 11794-2500) andby a speech-languagepathologist (SLP). Pre- andposttraining tokens were rated for quality by a listenerjury. Resultsshowed significant im- Past research indicates that the lexical access of emotion words is provementfor boththe ISTRA-trainedconsonant/l/, and the SLP-trained influencedby thedimensions of evaluationand activity. Increased reaction consonant/0/. However,only one of the two vowel contrastsfor each time to a lexical decisiontask usingemotion words and nonwordswas speakerimproved significantly. ISTRA-trained sounds which showed sig- predictedby low loadingson evaluationand activityas determinedby nificantimprovement did so for bothtrained and untrainedwords. Two ratingson semanticdifferential scales fL. H. Wurmand D. A. Vakoch,J. untrainedphonemes, /r/ and/U/, alsoimproved significantly, possibly in- Acoust.Soc. Am. 95, 2974(1994)]. The current study examines the extent dicatinga generalizationof improvedsounds to otherphonological dis- to which evaluation,activity, and potency influence lexical accessof words tinctionsin English.These results are promisingas regardsthe usefulness morerepresentative of the entirelexicon [C. E. Osgood,J. Pets.Soc. of speechrecognition technology for pronunciationtraining. [Work sup- Psychol.12, 194-199 (1969)].Implications for a dimensionalmodel of the portedby NIHDCD SBIR Program.] structure of the lexicon are discussed. 5pSP4. Training effectsfor identificationof syntheticspeech tokens 5pSP2. Teaching phoneticsto undergraduatesat the University of for listeners with normal and impaired hearing. Amy R. Horwitz Washington. SharonHargus (Dept.of Linguist.,GN-40 PadelfordHall, and ChristopherW. Turner (Dept. of Commun.Sci. and Disor&, 805 S. Univ.of Washington,Seattle, WA 98195)and KatharineDavis (Univ.of CrouseAve., Syracuse,NY 13244-2280) Washington,Seattle, WA 98195) Training effectsfor identificationof speechlikestimuli having fre- In 1993, the Instrumentationand LaboratoryImprovement Program of quency, amplitude,and temporal characteristicsbased upon natural the NationalScience Foundation awarded $23,960 to the Universityof consonant-vowel(CV) speechtokens were measured.Two typesof dy- Washington(who providedmatching funds) for phoneticsfacilities for namic speechstimuli were synthesized.Specifically, in the first type for- undergraduateeducation. In accordancewith NSF guidelines,a summary mantswere representedby puretones and in the secondby sweepingthree of the progressto date is presentedhere. Fundswere used to purchasea "formant" filters acrossa voicing-sourcespectrum, to more closely ap- DOS machineand a Macintosh,which run softwareincluding programs proximatenatural speech. Following a brief familiarizationperiod, normal- for signal processing,speech synthesis, statistics, word processing,and hearingand hearing-impairedsubjects listened to and identifiedsix CV graphics.Also purchasedwere analogand digitaltape recorders, a mixer, syllablesin a closed-setformat. The order of presentationfor the type of microphones,and other speech analysis equipment including a nasometer synthesizedspeech tokens was counterbalancedso that initially half of the and an airflowmeter. A sound-treatedbooth in which to do recordingsand subjectswere testedwith the pure-tonespeech syllables while the other perceptionexperiments has been built. This laboratoryhas enabledus to half were testedwith the broader"voiced format" speech.Data were offer a comprehensivecourse in LinguisticPhonetics at the undergraduate collectedover the courseof severalmonths. Substantial training effects level,and has allowed us to supplementthe offeringsof othercourses. For wereobserved for bothtypes of speechstimuli, with all subjectsultimately example,undergraduates in the Dept.of AsianStudies learned about pro- achievingsimilar identification scores for bothtypes of syllables.[Work nunciationin Japanese,students in the EnglishPhonology and Morphol- supportedby NIDCD]. ogy courselearned about individual differences in the implementationof phonology,and studentsin the LanguageAcquisition course learned about 5pSP5. Vocal correlatesof interpersonalissues. DouglasA. Vakoch, the phoneticcharacteristics of "motherese."There are plansfor additional DeanA. Pollina,and Lee H. Wurm (Dept.of Psychol.,State Univ. of New equipmentwhich will enableus to teachstudents about speech perception York at Stony Brook, Stony Brook, NY 11794-2500) as well. Previousstudies have related different interpersonal styles to the fun- 5pSP3. Intelligibility training for foreign-accented speech: A damentalfrequency (F0) of subjects'speech. For example,high ratings of preliminary study. Catherine L. Rogers (Commun. Disorcl. Technol., pitch have been aaaociatedwith •clf-attributiona of dominanceand affili- Inc., 205 S. Walnut St., Bloomington,IN 47404 and Indiana Univ.), ation[K. R. Scherer,J. Psychol.Res. 3, 281-298 (1974)],which are two JonathanM. Dalby (Commun.Disor& Technol.,lnc.), and Gladys dimensionsalong which interpersonalissues have been definedfL. E. DeVane (Commun.Disord. Technol., Inc. and IndianaUniv.) Alden, J. S. Wiggins,and A. L. Pincus,J. Pers.Assessment 55, 521-536 (1990);L. S. Benjamin,Psychol. Rev. 81, 392-425 (1974)].Similarly, A computer-basedspeech training system, the IndianaSpeech Training subjectswith greaterpitch variabilityhave been judged to be more be- Aid (ISTRA), hasbeen shown to be clinicallyeffective for improvingthe nevolent[G. B. Ray,Commun. Monographs 53, 266-276 (1986)].Previ- speech of hearing-impaired and phonologically disordered individuals ous studies,however, have failed to focuson the problematicaspects of [Kewley-Portet al., Clin. Ling. Phon.5, 13-38 (1991)].The potential interpersonalfunctioning. The currentstudy reports on the acousticalcor- valueof speechrecognition technology for thetraining of foreign-accented relatesof six typesof interpersonalproblems: (1) excessiveconcern about speech,using an overallmeasure of speechquality as feedback,was as- theevaluations of others,(2) impactof pastabuse, (3) dissatisfactionwith sessed.Phonological errors in Englishspoken by two nativeMandarin therapist,(4) excessiveresponsibility for panner,(5) fearof abandonment, 3348 J. Acoust.Soc. Am., Vol. 96, No.5, Pt. 2, November1994 128thMeeting: Acoustical Society of America 3348 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp and(6) ineffectiveinterpersonal responses. For females only, a higher Whenhearing a wordwhich is continuouslyrepeated, listeners report meanF0 waspredictive of botha greatersense of excessiveresponsibility that the word seemsto changeinto differentforms and then vacillates forpartner (p<0.05) and an increased fear of abandonment(p<0.05). amongthese forms. This auditoryillusion has been called the verbal trans- formationeffect [R. M. Warren,Br. I. Psychol.17,249-258 (1961)] and is 5pSP6.Neuroticism and opennessare predictedby fundamental frequencyof speech.Douglas A. Vakoch,Dean A. Pollina,and Lee H. consideredto be causedby thelack of verbalcontext, produced by the repetition.This study further investigated the role of contextin theinter- Wurm(Dept. of Psychol.,State Univ. of NewYork at Stony Brook, Stony Brook, NY 11794-2500) pretationof auditorystimulation. Twenty-six listeners heard the individual, continuous,repetition of sixstimuli: an English sentence, anEnglish word, anda Chineseword (each played forward and backward). It wasassumed Thefundamental frequency (F0) of speechhas been used for examin- ingboth transient emotional states [D. A. Vakoch,J. Acoust. Soc. Am. 95, thatlisteners will reportverbal transformations with all stimuliexcept the Englishsentence, since only this condition contained sufficient contextual 2974(1994)] and more stable personality traits. For example, low per- cues.Results showed that both forms of theEnglish sentence were treated ceivedpitch has been associated with attributions of highemotional sta- bility[K. R. Scherer,Eur. J. Soc.Psychol. 8, 467-487(1978)]. In the in the samemanner, and that significantlymore verbal transformations were reportedwith the words. currentstudy, characteristics derived from F0 wererelated to fiveperson- alitytraits as measured by theNEO-PI: neuroticism, extroversion, open- 5pSPI0. Control experimentson the frequencyscale of speech ness,agreeableness, and conscientiousness. A high degree of opennesswas intonation.Dik J. Hermesand H. H. Rump (Inst.for Percept.Res. IPO, predictedby a highmean F0 of an utterance(p<0.025) and by a great P.O. Box 513, 5600 MB Eindhoven,The Netherlands) variabilityin F0 withinan utterance(p<0.004). The bestpredictor of neuroticismwas peak F0 withinan utterance, with subjects scoring high Accordingto Hermesand Van Gestel[J. Acoust. Soc. Am. 90, 97-102 onthis scale having a highermaximum F0 (p<0.021).The latter finding, (1991)],prominences of accent-lending pitch movements in different reg- in conjunctionwith previous research on attributions of emotional stability, istersare equal when their excursion sizes are equal on the ERB-rate scale. suggestsa convergencebetween objective acoustical measures and sub- A reanalysisof theirexperiments showed that an octaverelationship be- jectiveperceptions of personality. tweenthe high pitch levels in thedifferent registers may have been crucial. In orderto testwhether this factor influenced the outcome of theirexperi- 5pSP7.AIIophonic variation in spokenand sung speech. Ray ments,adjustment experiments were performedwith stimuliin different Daniloff,Kathy Wolf, GeorgeLarsen (Dept.of Speechand Hear. Sci., low andhigh registers. The results,supporting the ERB-rate scale hypoth- Univ. of North Texas, EO. Box 5008, Denton,TX 76203-0008),and esisof Hermesand Van Gestel, showed that the octave relationship had no Lee Evans (Univ.of NorthTexas, Denton, TX 76203-0008) systematicinfluence on theresults. In an additionalexperiment, stimuli were resynthesizedfrom a male and a female voice in order to test the Researchsuggests that sung and spoken speech differ systematically in effectof the speaker'snatural pitch range. The maleand female stimuli termsof laryngeal,intonational, rhythmic, and articulatory performance. In gaveabout the sameresults. In sum,the effectof pitchexcursion on thepresent study we examined control of pronunciationrules [Ladefoged, prominenceis veryrobust. An unexpectedfinding was that, on average, the A Coursein Phonetics(HBJ, 1993)] in singers.Three doctoral students of excursionsof thepitch movements in the highregister were about 0.15 E vocalperformance sang and then spoke a setof sentences.Simple melo- (0.5-1 semitone)larger than those of the pitchmovements in thelow dieswere composed to fit therhythmic figure of eachsentence. The sen- registerwhen lending equal prominence. tencescontained five examplesof eachof 24 pronunciationrules of En- glish.Recordings were transcribed, rhythm and stress patterns noted, and 5pSPll. Some control experimentson a model for prominence acousticanalysis was performed (GW Soundscope)to ascertain the degree perception.H.H. Rumpand Dik J. Hermes (Inst.for Percept.Res. IPO, to whicheach pronunciation rule was/was not implementedin sungversus P.O. Box 513, 5600 MB Eindhoven,The Netherlands) spokenproduction. Results indicate that singing induces both systematic andnonsystematic changes in pronunciationacross singers which can be Accordingto the modelproposed by Hermesand Rump[J. Acoust. relatedto themore stereotyped production strategies associated with sing- Soc.Am. (in press)]the prominencelent by accent-lendingpitch move- ing. mentsis proportionalto the pitch-leveldifference between the vowel nucleusof theaccented syllable and the vowel nucleus of the preceding 5pSP8. Effects of speakingrate, focal stress,and distinctivevowel syllable.The pitch level on the lower declinationline or baselineand the length on syllable-internaltiming in Norwegian. Dawn M. Behne pitchlevel on the upperdeclination line or toplineare thus regarded as and Bente Moxness (Linguist.Inst., Univ. of Trondheim,N-7055 equallyimportant. By varyingthe heightof the pitchlevels on the base- Dragroll, Norway) linesthis assumptionwas testedagainst the alternativeassumption that listenersequated pitch levelson the toplineof eachof the stimuliwhen The relativetiming of consonantsand vowelsof a syllablecan be adjustingprominences to be equal.Results showed that pitch levels on the affectedby factorssuch as speaking rate, focal stress, and distinctive vowel toplineswere adjustedto be moreor lessequal, but thatthe pitch-level length.Speaking rate and focal stresstend to have a global affect on differencebetween the low and the high pitch level influenced the adjusted syllable-internaltiming, whereas the effectof distinctivevowel length in heightof thehigh pitch level, too. It is concludedthat the proposed model Norwegianis generallybelieved to be localizedto the syllablerhyme. makesclaims about the relevanceof the positionof the low pitchlevel Whenthese factors converge on a syllable,the syllable-internaltiming whichis toostrong. The roleof pitchlevels in relationto theperception of simultaneouslyreflects their concurrenteffects. The goal of the present prominencewill be discussed. studyis to examineand characterize the concurrent effects of speaking rate,focal stress, and distinctive vowel length on syllable-internaltiming 5pSP12. Prosodiccharacteristics of register variation in the read of C1VC2 components.Conversations were developedin which 12 Nor- speech of adult native speakers of French. Andrea G. Levitt and wegianCVCs containing/i,o, a, i:, o:, a:/were eitherfocused or nonfo- JeannineGeoffrion (WellesleyCollege, 106 CentralSt., Wellesley,MA cusedby the discourse.The set of conversationswas producedat three 02181-8289) speakingrates by native speakersof Norwegian.Results indicate that speakingrate and focal stresshave an overallaffect on the timingof Ten female native speakersof Frenchwere askedto read two para- componentsin the syllable.In addition,the effectsof distinctivevowel graphsin eachof threeregister styles: to a friend (native),to a nonnativc lengthand focal stress on componentsof thesyllable rhyme were found to speaker(foreigner talk), and to a 1-year-oldchild (child-directed speech). be interdependentacross speaking rates. These findings are discussedin Therewere significant differences in thespeech rate, number and length of termsof syllable-and rhyme-internal timing. pauses,and mean F0 andF0 rangeamong the three speech styles. Speech ratewas significantly different for eachof the registers,with foreignertalk 5pSP9.Forward and backwardpresentation of Chineseand English theslowest, native speech the fastest, and child-directed speech in between speechin the verbal transformationeffect. MagdaleneH. Chalikia, the othertwo. A similarpattern of significantdifferences emerged for RachelWaldstein, and William J. Stech (Dept.of Psychol.,Moorhead pauselength and number of pauses,again with foreignertalk showing the State Univ., Moorhead,MN 56563) mostpauses and the longestaverage pause length, native speech showing 3349 J. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November1994 128th Meeting:Acoustical Society of America 3349 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp the fewestand shortest pauses, and child-directed speech in betweenthe 50 ms,or roughlyhalf the durationfrom the beginningof the unstressed othertwo. Mean F0 wassignificantly higher for child-directedspeech than vowel to the beginningof the stressedvowel. for the othertwo registers,which did not differ from one another.The three registersdid differ significantlyfrom one anotherin termsof F0 range, 5pSP16.Perceptual centers in Japanesedisyllables. Alan Bell (Dept. of Linguist., Box 295, Univ. of Colorado, Boulder, CO 80309) and with child-directedspeech showing the greatestF0 range,native speech thesmallest, and foreigner talk in betweenthe other two. [Worksupported YasunofiMorishima (Dept. of Psychol.,Box 345, Univ. of Colorado, Boulder, CO 80309) by NIH GrantNo. 1 R15 HD28173-01.] 5pSP13. Prosodic cues of repetitions in Spanish spontaneous Most researchon perceptualcenters has been based on monosyllables discourse. Pilar Munday (Inst.for Speechand Lang.Sci., NYU, 719 in languageswith stress;indeed the term "stressbeat" is sometimesused Broadway,5th fl., New York, NY 10003) for thesame phenomenon. Accent in Japaneseis mainlyrealized by pitch; amplitudeand durationare relativelyunimportant. Perceptual centers in When Spanishspeakers repeat words or phrasesin discourse,some disyllabicwords perceived by fourJapanese were used to investigatethe repetitionsare due to false startsor hesitationswhile othersare usedfor characteristicsof perceptual centers in thecontext of pitchaccent. Percep- emphasisor clarity.These will be referredto as "hesitations"and "em- tual centersoccur later in disyllableswith longerconsonant onsets, by a phasis"repetitions, respectively. Although the purpose of therepetition can magnitudecomparable to thatfound for stressedmonosyllables [e.g., Coo- often be determinedfrom discoursecontext or part of speech,this study per et aL, Percept.Psychophys. 39, 187-196 (1986)] andfor Japanese showsthat there are also prosodiccues that serveto distinguishthe two monosyllables[Hoequist, Lang. Speech 26, 367-376 (1983)].The effect types.The speechdata consist of all repetitionsuttered by a male Colom- of lengtheningthe tail (the portionfollowing the initial consonant)of bian speakerover the courseof a 1-h spontaneousconversations. The disyllablesalso corresponded in magnitudeto that foundpreviously. Ac- following acousticinformation was obtainedfor each utteranceand its cent placementhad little or no effect. The sameeffect of onsetduration repetition:duration, peak amplitude, average amplitude, and durationof was foundfor initiallyaccented and finallyaccented disyllables whose anyintervening pause. Pauses occur more often and tend to be longerin durationand amplitude contour were held constant.A smallaccent differ- hesitationrepetitions. Contrary to previouslyreported findings for English, encewith respectto the effectof tail durationwas foundin wordsof the however,a pauseis frequentlynot present.The firstelement of the hesi- sameduration but retainingdifferences in amplitudecontour. The results tationrepetition tends to be longerthan the second.Amplitude does not areconsonant with the greater prominence effects found for amplitudeand appearto differentiatethe two typesof repetitions.The resultssuggest that durationthan for pitchin rhythmicperception. durationsis the mostimportant cue for distinguishingbetween types of repetitions. 5pSP17. Spectral analysis of amplitude envelopesof bandpass filteredspeech. King-Leung Kong (Dept.of Psychol.,Univ. of Hong 5pSP14. Perceptual centers as an index of speechrhythm. Charles Kong,Hong Kong) AndrewHarsin and Kerry P. Green (Natl.Ctr. for NeurogenicCommun. Disord., Univ. of Arizona, Tucson,AZ 85721) The amplitudeenvelopes of rectifiedbandpass filtered speech have beenfound to provideuseful cues for speechperception [K. W. Grant,L. One of the obstaclesto investigatingspeech rhythm has been the dif- D. Braida,and R. J. Renn,J. Acoust.Soc. Am. 95, 1065-1073 (1994)].An ficulty in locatingthe syllabicbeat. This studyattempts to addressthat analogterminal was built to yield 25 suchenvelopes from filterswith difficultyby usingperceptual centers (p-centers) as an indexof speech center(carrier) frequencies from 150 to 4850 Hz. Each envelope was then rhythm.P-centers of syllablesextracted from naturalutterances were de- subjectedto anotherround of bandpassfiltering and rectification to yielda terminedboth by listenersusing a methodof adjustmentprocedure and by modulationspectrum of up to ninechannels with center(modulation) fre- an acousticp-center model. The phoneticstructure (syllabic onset) and quenciesfrom half the carrierfrequency to 700 Hz. The spectrawere stresspatterns of the syllablesin the utteranceswere varied, and the effects examinedfor cuesfor theidentification of voicing,fundamental frequency, of thesemanipulations on the utterances'rhythms were investigated.As andconsonants. Voicing was generally characterized by theconcentration expected,the p-centersof the syllablesvaried systematically with their of formantenergy at a singlecarrier and modulationfrequency, corre- own phoneticstructure. Preliminary findings indicate that the p-centerof spondingto the formantand fundamental frequencies, respectively. The the syllablesalso changes along with the p-centerof the previousor sub- second formant of the front vowel/i/and nasal release sometimes exhib- sequentsyllable so as to maintaina relativelyconstant interval between the itedhimoral modulation spectra, suggesting multiple sources of modula- two p-centers.The studyalso examines the effectson rhythmof altering tion.Stop consonants and fricatives were characterized by elementsscat- stresspatterns, by determiningwhether unstressed syllables might influ- teredat highcarrier and modulation frequencies whose occurrences might encep-centers. The resultswill he discussedin termsof dynamiccon- notcoincide. Some consonants could be identifiedwith elements at spe- straintswhich might affect speech production. [Work supported in partby cificmodulation frequencies: e.g.,/g/and/j/suggested a 700-Hzsource NationalMultipurpose Research and Training Center Grant No. P60 DC- modulatingcarriers whose frequencies depended on thefollowing vowel. 01409 from the National Institute on Deafness and Other Communication Disorders.] 5pSP18.Prediction of speechtransmission quality of widebandand narrow-bandtelephone handsets using short-time Sub-band analysis 5pSP15.Perceptual centers are affectedby stresslocation in English and psychoacousticmodels. Winfried Krebber (Inst. f. El. disyllables. Alan Bell andDebra Halperin Biasca (Dept.of Linguist., Nachrichtentechnik,Aachen Univ. of Technol.(RWTH), D-52056Aachen Box 295, Univ. of Colorado,Boulder, CO 80309) Germany) The perceptualcenters of Englishdisyllables were investigated in two A predictoris presentedwhich estimatesthe meanopinion score experiments.Six subjectsparticipated in the firstexperiment, and five in (MOS)for a givenspeech sample from speech and noise transfer charac- the second.The firstexperiment compared initially stressed disyllables teristicsof a specifichandset applied to an artificialearl The criticalband with five onsetswhose duration varied from 4 (batter)to 180 ms •qatter). rateexcitation pattern is computedin 50-msblocks for originaland dis- Its resultsdemonstrated that initially stressed disyllables with longer onsets tortedspeech signals and additive room noise. For each block three psy- haveperceptual centers that are displaced relatively further from the acous- choacousticparame!ers are computed: An intelligibility index (1) isevalu- tic beginningof theword by aboutthe same amount as the difference in the atedusing SNR analysis in eachsub-band and considering simultaneous onsetdurations, in agreementwith earlierresearch on Englishmonosyl- maskingeffects. Naturalness (N) is estimatedby spectraldistance between lables[e.g., A. Cooper,D. Whalen,and C. Fowler,Percept. Psychophys. originaland distorted speech. A loudnessindex (L) is derivedfrom loud- 39, 187-196(1986)]. The second experiment compared initially stressed ness(computed similar to ISO532) using a trapezoidfunction: L decreases disyllableswith disyllablescomposed of a reducedfirst syllable and a if the loudnesswhich is exceededin 10% of time is lower than 15 soneor stressedsecond syllable, e.g., com'mute vs 'comet,holding the total dura- higherthan 45 sone.The MOS is predictedas a weightedsum of I, N, and tionof all itemsconstant. Again, longer onsets produced later perceptual L. Theprediction results were verified by an opinion test including totally centersfor both stresslocations, but the perceptualcenters of finally 442speech samples of severaltalkers which were filtered simulating typi- stresseddisyllables were later than those of initiallystressed ones by about caltransfer characteristics of handsets and presented in a noisyenviron- 3350 d.Acoust. Soc. Am., Vol. 96, No. 5, Pt.2, November1994 128thMeeting: Acoustical Society of America 3350 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp ment.Speech level and SNR were varied in a widerange. The comparison 5pSP22. Possibleusages of LPC error for the estimationof voice provesa good correlation (p=0.93 for all samples and p =0.96for speech characteristics.Sungbok Lee (Centrallnst. for theDeaf, 818 S. Euclid, levelsbelow 76 dB SPL). St. Louis, MO 63110) 5pSPI9.Cepstrogram and its applicationto speechanalysis Chiwei Usingthe autocorrelation method, LPC error signals were computed as Che and QiguangLin (CAIP Ctr., RutgersUniv., Piscataway,NJ differencesbetween the original waves and the predicted waves at each 08855-1390) timeinstant. Analyses of synthesizedand human vowel sounds show that the shapesand spectral contents of the instantaneouserror signals are Cepstrumcoefficients (including their different variants and/or deriva- almostidentical with thoseof the voicesource for synthesizedvmvel tives)are nowadays commonly utilized in automaticspeech recognition sounds,and that the instantsof glottalclosure are well definedas maxi- systems.Most adaptationalgorithms for robustspeech recognition also mally negativepeaks in the errorsignals for bothkinds of vowelsounds. makeuse of cepstmmcoefficients. It is thereforeimportant to havea tool Timeintegration of errorsignals was also performed. For malevoices the whichcan efficiently calculate and display cepstra. A computerprogram shapesof integratedand instantaneous error signals are found to be very hasbeen recently developed to displaythe cepstrogram of speech signals. similarwith thoseof EGG anddifferentiated EGG signals,respectively. Theprogram has the following features: (1) It computesboth linear pre- Thisresult supports the possibility that open and closed phases of thevocal dictionbased and FFT basedcepstra; (2) it displayscepstrum coefficients foldswithin each glottal cycle can be determinedfrom suchLPC error andtheir derivatives as a functionof timeand cepstmm index, as well as signals.It wasalso found that automatic detection of valleys(or peaks) in cepstrumcoefficients at a fixedframe (section displays); (3) it generates the integratederror signal may be a robustpitch estimation method for synthesizedspectra from cepstrum coefficients. In addition,the program voicedspeech segments including synthetic diplophonic sounds. These and canbe used to segmentand playback speech waveforms. The program has otherresults suggest that these simple LPC erroranalyses may provide beenutilized to studyvariations in cepstrumcoefficients caused by speaker significantinformation about the voice source. variabilityand channel differences. The tool is a usefulsupplement to 5pSP23.Speech stress classification and feature analysisusing a conventionalspectrograms for speechanalysis. (The program is codedin neural network classifier. Brian D. Womack and John H. L. Hansen C andruns in theX-window environment. It is availableupon request.) (RobustSpeech Processing Lab., Dept. of ElectricalEng., Duke Univ., 5pSP20.The PEACCmethod of characterizationof dynamicaspects Box 90291, Durham, NC 27708-0291) of speech. Jim Talley (Dept.of Linguist.,501 CalhounHall, Univ. of Variabilityin speechproduction due to taskinduced stress contributes Texasat Austin,Austin, TX 78712) significantlyto lossin speechprocessing performance. A new neural net- workalgorithm is formulatedwhich classifies speech under stress using the In the phonetics/speechperception community, the assertionthat dy- sUS^Sstress database.Five spectral parameterrepresentations (Mel, namicaspects of thespeech signal are employed in robustspeech decoding A-Mel,A2-Mel, Auto-Corr-Mel, andCross-Corr-Mel cepstral) are consid- is not particularlycontroversial. Though an increasingnumber of studies ered as potentialstressed speech telayers. Eleven stressconditions are areaddressing the various dynamic cues of speech,quantitative, analytical consideredwhich includeAngry, Clear, Fast, Lombard, Loud, Normal, researchis hamperedsomewhat by a lack of establishedmethods. Methods Question,Slow, and Soft speech. Stressed speech classification using these for studyingdynamic phenomena are much less well developedthan those featuresis evaluatedwith respectto (i) pairwiseclass separability, (it) an for morestatic properties. This paperproposes a newmethod for charac- objectivemeasure of pairwiseand globalfeature separability, and (iii) terizingdynamic aspects of speech,the PiecewiseExponential Approxi- analysisof articulatoryvocal tract area functions. Perturbations in speech mationwith Continuity Constraints (PEACC) method, to helpremedy this productionunder stress are reflected to varyingdegrees in the five speech stateof affairs.As its namesuggests, PEACC performs piecewise fitting of featurerepresentations. A neural network classifier over phonemeparti- exponentialsegments--ye'•+/•, -•c•0•to thesampled signal. Dy- tionscan achievegood speakerdependent classification performance namicprogramming is utilizedin globalsequence optimization where (80.6%)when stress conditions are combined into six groupsof related MSE is minimizedwithin the solutionspace permitted by the constraints stressdomains. The implicationof reliablestress classification will be on continuity.This methodhas broadapplicability and produceslow- discussedfor applicationssuch as monitoringspeaker state, improving distortionfits at a specifiablelevel of detail;however, its principle strength, naturalnessof speechcoding, and increasingrobustness of speechrecog- from theperspective of speechscience research, is thatits resultingsignal nizers in adverse conditions. transitionparameters have direct, intuitive interpretations. The papercon- cludeswith a brief examinationof the resultsof applyingPEACC to a 5pSP24. Many-valued logic is reflected in formant location and corpusof formanttrack data. [Work supported by NSE] spectral composition. Dean A. Pollina,Douglas A. Vakoch,and Lee H. Wurm (Dept.of Psychol.,State Univ. of New York at StonyBrook, 5pSP21.Analysis of quality factors in syntheticspeech produced by StonyBrook, NY 11794-2500) rules. Eri Miyazawa and Hiromi Nagabuchi (NTr Telecommun. NetworksLabs., Midori-cho, Musashino-city, Tokyo, 180 Japan) Variationin the truthvalue of propositionshas been shown to yield changesin cognitiveevent-related potentials (ERPs) [D. A. Pollinaand N. This paperinvestigates how variousfactors affect the qualityof syn- K. Squires,Psychophys. 30, S52 (1993)]. Given the connectionbetween theticspeech produced by rules.Using rules to synthesizespeech will be thearousal of thecentral nervous system and peripheral systems, the same an importanttechnique for providingvarious telecommunication services paradigmthat was usedto detectmany-valued beliefs via ERPs was used in futureintelligent networks. The qualityof syntheticspeech is generally to detectdegree of beliefby an acousticalanalysis of thevoice. Degree of measuredby subjectivelyevaluating the speechfrom the viewpointof beliefwas manipulatedby havingsubjects solve a murdermystery, after intelligibility,or by comparingit with the qualityof othertypes of syn- whichthey learned facts associated with threepeople: (1) the personthey theticspeech. However, the developmentof a practicalspeech synthesis mostsuspected of committingthe murder,(2) theperson they judged next methodfor usein telecommunicationnetworks requires an overallquality mostlikely to be themurderer, and (3) theperson they knew could not be evaluation,including intelligibility and naturalness. The qualityshould be the murderer,Articulatory precision of subjects'utterances was measured comparedwith that of naturaltelephone speech. To establishan overall by formantlocation and spectral composition [F. J. Tolkmittand K. R. qualityevaluation method, the effectsof severalfactors on the overall Scherer,J. Exp. Psychol.Human Percept. Perform. 12, 302-313 (1986)]. quality(expressed by MOS) of speechsynthesized by severalJapanese Thesemeasures were related to thedegree to whichsubjects believed each text-to-speechsystems are quantitativelycompared with the effectsof us- statement to be true. ing additivespeech-correlated white noiseas a naturalspeech material. 5pSP25. Lie detection based on ohonator• processes. Dean A. Experimental results snow t•at such factors as subject, listening experi- Pollina,Douglas A. Vakoch,and Lee H. Wurm (Dept.of Psychol.,State ence,average pitch frequency, and text affectsynthetic speech more than Univ. of New York at StonyBrook, StonyBrook, NY 11794-2500) naturalspeech. Quality evaluationcharacteristics due to thesefactors are discussedand an overallquality evaluation method for syntheticspeech is Deceptionhas been shown to be associatedwith changesin the fun- proposed. damentalfrequency (F0) of vocalizations.For example,during attempted 3351 d. Acoust.Soc. Am., Vol. 96, No. 5, Pt. 2, November 1994 128th Meeting:Acoustical Society of America 3351 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp deception,F0 typicallyincreases [P. Ekman,W. V. Friesen,and K. R. ancesat two pointsin time: prior to establishingany belief aboutthe Scherer, Semiotica 16, 23-27 (1976); L. A. Streeter, R. M. Kraus, V. statement,and after having a belief. By analyzingthe samephrase at Geller, C. Olson, and W. Apple, J. Pets. Soc. Psychol.35, 345-350 baselineand after the belief manipulation,more precisemeasurements (1977)].The currentstudy examines changes in F0 for the identicalutter- correspondingto belief can be madethan in previousstudies. FRIDAY AFTERNOON, 2 DECEMBER 1994 BALLROOM B, 1:15 TO 5:00 P.M. Session5pUW Underwater Acoustics:Propagation II Henrik Schmidt, Chair Departmentof OceanEngineering, Massachusetts Institute of Technology,Cambridge, Massachusetts 02139 ContributedPapers 1:15 1:45 5pUWl. Single-mode excitation in a laboratory waveguide using 5pUW3. An efficient broadband normal-mode model for feedbackcontrol. JohnR. Buck (Dept.of Appl. OceanPhys. and Eng., acoustoelastlcocean environments. Evan K. Westwood (Appl. Res. Woods Hole Oceanogr.Inst., Woods Hole, MA 02543 and Res. Lab. of Labs., P.O. Box 8029, Univ. of Texas at Austin, Austin, TX 78713-8029) Electron.,MIT, 77 MassachusettsAve., Cambridge,MA 02139-4307), A recentlydeveloped normal-mode model [E. K. Westwoodet al., J. Mark Johnson,James C. Preisig,and JoskoCatipovic (WoodsHole Acoust.Soc. Am. 95, 2908(A) (1994)] for acoustoelasticocean environ- Oceanogr.Inst., Woods Hole, MA 02543) mentshas been extendedto perform broadbandcalculations. The set of complexmode eigenvaluesat the highestfrequency of interestis first Previouswork formulated an adaptivealgorithm for excitinga single found.Then each eigenvalue kn is trackedas a functionof frequencydown modein a shallow-waterwaveguide using feedback control [Buck et aL, J. to the lowestfrequency of interest.Analytic derivatives with respectto Acoust.Soc. Am. 95, 2927(A)(1994)]. This paper presents results ob- frequencydk,/dco are used to extrapolatein frequency,and step sizes are tainedusing this algorithmin a laboratorywaveguide experiment under a adjustedadaptively. When the stepsize exceeds the FFF bin width,linear varietyof conditions.Unlike previouslaboratory single-mode excitation interpolationof eigenvaluesmay be used.Examples of broadbandcalcu- experiments[Clay andHuang, J. Acoust.Soc. Am. 67, 792-794 (1980); lationsare given.[Work supported by theARL InternalResearch and Gazanhesand Gamier, ibid. 69, 963-969 (1981)],our algorithm does not DevelopmentProgram.] requirea priori environmentalknowledge, but only the sound-speedpro- file at the feedbackarray. The experimentresults to be presenteddemon- stratethe algorithm'sconvergence behavior and robustness to environmen- 2:00 tal mismatch.If time permits,present experimental results illustrating the 5pUW4. A method for including lateral waves in normal-mode abilityof the algorithmto tracktime variationsin the channelwill alsobe calculations. Evan K. Westwood (Appl. Res. Labs.,P.O. Box 8029, presented.[Work supported by ONR andARPA.] Univ. of Texasat Austin,Austin, TX 78713-8029) A methodfor includingthe lateral(or head)wave in a normal-mode propagationmodel [E. K. Westwoodet al., J. Acoust.Soc. Am. 95, 1:30 2908(A) (1994)] for acoustoelasticocean environments has been devel- 5pUW2. Advances in underwater acoustic normal-mode oped.The methodconsists of replacingthe originallower half-space with computations. ScottJ. Levinson,Carol V. Sheppard,and StephenK. a thicklayer having a constantsound speed but a smallgradient in attenu- Mitchell (AppLRes. Labs., Univ. of Texasat Austin,Austin, TX 78713) ation.Below the attenuatinglayer, the new lower half-space is givenpa- rameterssuch that there is no mismatchat the half-spaceinterface. As a result,(1) thebranch point corresponding to the critical angle in •hehalf- Recently,an efficient,numerically robust algorithm for calculating spaceis movedupward in thecomplex k plane(where k is horizontalwave acousticnormal modes was shown to havemore than an orderof a mag- number),(2) thePekeris branch line integral is alsomoved upward such nitudeimprovement in speedwhile maintaining high accuracy over other thatit becomesnegligible, and (3) modesappear in thecomplex k plane algorithms(submitted to JASA by the authors,June '94). A limitation betweenthe old and new branch points. The cost of introducingthe thick remains,however, in its dependenceon presampledwave numbers in the layeris notgreat because Airy functionsolutions are used in eachlayer. searchfor the rootsof the characteristicequation (eigenvalues). Since Removalof thePekeris branch line integral, in conjunctionwith inclnding coarsewave-number presampling may resultin someeigenvalues remain- theleaky modes, makes the mode solution represent the complete acoustic ing undetected,the prgsampllngpart of thi$ ½od•is the mosttime conaura field. [Work supportedby the ARL InternalResearch and Development ing poHion•paRicularlyfor multichannelenvironments. We introducea Program.] sixthorder) are calculatedto locallyapproximate the numericallyrobust characteristicequation with Pade'approximants when finding successive 2:15 eigenvalues.•e requirementof wave-numberpresampling is thereby 5pUW5. A study of the influence of an offshore rise on avoidedand eigenvalueroot findingis achievedwith a superlinearcon- low-frequency modal propagation. Thomas N. Lawrence, Wade vergenceproperty. Its speedand accuracy will be comparedwith previous Trappe,and Nancy R. Bedford (Appl. Res. Labs.,Univ. of Texasat methodsfor singleand multichannel ocean acoustic environments. [Work Austin,P.O. Box 8029, Austin,TX 78713) supposedby the AdvancedSumeillance Acoustic Prediction System (AS•S) DevelopmentforIUSS Program of theSpace and Naval Wadare Simpleup slope propagation of underwater acoustic energy can usually SystemsCommand (SPAWn, PMW 181-1).] be modeledby an adiabaticnormal-mode approximation, provided the 3352 J.Acoust. Soc. Am., Vol. 96, No.5, Pt.2, November1994 128thMeeting: Acoustical Society of America 3352 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp slopeis nottoo severe. Bottom interacting paths in suchan environment 3:00-3:15 Break areusually sufficiently attenuated to make consideration of mode coupling unnecessary.An environmentfurther complicated by an offshorerise can 3:15 causeadditional acoustic energy to be introducedinto lower-ordermodes dueto bottominteraction. These low-order modes will thenpropagate in 5pUW8. Shallow-watertime seriessimulation using normal-mode deepwater until encounteringthe continentalshelf. Experimental results theory in range-independentand range-dependentenvironments. fromthe Arctic Ocean between 25 and45 Hz suggestsuch propagation GeoffreyS. Royal,David P. Knobles,and Robert A. Koch (Appl.Res. conditions.These results, and their interpretationin the contextof a Labs., Univ. of Texas at Austin,Austin, TX 78713) coupledmode study will be presented.Emphasis will be placedon the Broadbandnormal-mode model analyses of propagationin a shallow- conditionsunder which mode coupling will occur,and whenit mustbe water range-independentenvironment and in a wedgeenvironment are consideredin predictionand localization problems. The coupledmode presented.The modelis firstused to calculatereceived time seriesfrom a model,COUPLE JR. B. Evans,J. Acoust.Soc. Am. 74, 188-195 (1983)], pointsource for a rangeinvariant shallow-water acoustic environment with is usedas the vehicle for thisstudy. Additional approximation schemes of a constantwater sound-speedmedium and a penetrablebottom. Range obtaininga coupledmode result will be exploredwith the objectiveof invariantmode model time series are compared to actualexperimental data obtaininga fasternumerical solution. Comparisons will be madewith [C. Tindieet al., J. Acoust.Soc. Am. 81, 288-293 (1987)]and to time adiabaticnormal mode, and parabolicequations models. seriesthat were calculated using a ray modelthat includesbeam displace- ment [E. Westwoodand C. Tindie, J. Acoust.Soc. Am. 81, 1752-1761 (1987)].The timeseries from both the modeand ray modelsagree with 2:30 each other and with the measureddata. In addition, time series from an adiabaticmode modelfor a shallow-waterwedge environment are com- 5pUW6. Trans-Arctic propagation effects of changes in ice paredto theexperimental results obtained by C. Tindieet al. [Worksup- morphology.Henrik Schmidt and Brian Tracey (Dept.of OceanEng., portedby IR&D Fundat AppliedResearch Laboratories, The Universityof MIT, Cambridge,MA 02139) Texasat Austin.] The objectiveof theTrans-Arctic Propagation (TAP) experimentcar- 3:30 ried out in the springof 1994 was to investigatethe feasibilityof using acousticthermometry for inferring changesin the Arctic climate [P. 5pUW9. Characterizing nonadiabatic ocean acoustic environments. Mikhalevsky,J. Acoust.Soc. Am. 94, 1760(A)(1993)]. An importantissue R. L. Field,T. H. Ruppel,and M. K. Broadhead(Code 7173, NavalRes. Lab., StennisSpace Center, MS 39529-5004) is whichacoustic property will providethe strongestclimate change sig- nature.The sensitivityof variousproperties of theacoustic field to changes In range-dependentenvironments, the adiabaticassumption, which ne- in ice volumewas investigated theoretically. A perturbationformulation for glectsdiscrete mode coupling, is oftenmade. Up continentalshelves and in 3-D scatteringfrom roughice hasbeen combined with the KRAKENnormal- shallow-waterregions, abrupt changes in the environmentmake this as- modecode to providea modelof the second-orderstatistics of the acoustic sumptionsuspect. An issuein theseenvironments is the degreeto which field.Such a hybridmodel has been shown to provideexcellent agreement the adiabaticassumption is valid. Transmissionloss calculationsusing with historicalArctic transmissionloss data [LaPageand Schmidt,J. both a parabolicequation and coupledmode models show, that for steep Acoust.Soc. Am. 96, 1783-1795(1994)]. We use this model to investigate slopes,much more energy reaches the shelffrom deepwater than predicted the sensitivityof deterministicproperties of the coherentfield, such as by the adiabaticapproximation. This increasein shelfenergy is shownto modalloss, and modal phase and group velocity, to changein ice thickness be due to discretemode coupling. In thisstudy, changes in energyflux with and roughnessstatistics. In addition,the modelhas been use to investigate range are used as a criterion for when the adiabaticassumption breaks down.The flux is computedfrom a parabolicequation model in upslope the sensitivityto changesin the ice coverof the higher-orderstatistics such environmentsas a functionof range; frequency,and slope angle. It is as cross-modalcorrelation, and spatialcorrelation in general.Comparing shownthat rapidflux variationsare goodpredictors of whenthe adiabatic thesetheoretical sensitivity measures, we discussthe potentialperfor- approximationbreaks down and mode coupling becomessignificant. manceof bothdeterministic and statistic acoustic thermometry in the Arc- [Work supportedby ONR, ProgramElement 602435N, with technical tic. managementprovided by the NavalResearch Laboratory.] 3:45 2:45 5pUWI0. Compound-matrixmethods for computationof wave fields 5pUW7. An efficient algorithm for calculating depth dependent in horizontallylayered fluid-solid media. Sven Ivansson (Dept. of modal phase and for mode identification in normal-mode models Hydroacoust.and Seismol.,Natl. DefenceRes. Establishment(FOA), basedon the Airy equation. J. LeMondand RobertA. Koch (Appl. S-172 90 Stockholm,Sweden) Res. Labs., Univ. of Texas at Austin, Austin, TX 78713) The wave field is decomposedinto its frequency-wave-numbercom- The underwater acoustic normal modes of multichannel environments ponents,and a compound-matrixODE theoryis formulatedfor multiregion fluid-solid media usingmultipoint boundary conditions. Forward propa- mayexhibit closely spaced eigenvalues that require a fine horizontalwave- gation of compoundentities is done to a matching depth, from which numbersample in modelsbased on theAiry equation.Also, for broadband stabilized backward propagationto the receiversis performed. Wave- applicationsthe maximumfrequency difference that permitsaccurate in- numberintegration as well as modal synthesisis covered.Source arrays terpolationis limitedby the frequencydifference of themodal depth func- andreceivers may be arbitrarilylocated. An appropriateadjointproblem is tions.A straightforwardand numericallyefficient algorithm to constructa definedand solved.The formulafor modalexcitation coefficients is gen- monotonicdepth-dependent phase using the propertiesof the Airy func- eralizedto cover leaky modes,which have an exponentialincrease with tions is presentedthat significantlyreduces the computationalburdens depth.Three methods for stableand automatic computation of modaldepth imposedby theseconstraints. The totalphase change of a modeacross the functions,in solid as well as fluid regions,are proposed.In work by M. B. depthof the waveguidegives the modenumber, modulo •r, which is es- Porterand E. L. Reiss[J. Acoust.Soc. Am. 77, 1760-1767 (1985)] the scntial in adiabatic normal-mode calculaliona for ,angc variable environ- mode shapes in the solid bottom were left aside, and the method by F. mentsbecause the acousticfield mustbe propagatedfrom one environment Schwabet al. [Bull. Seismol.Soc. Am. 74, 1555-1578 (1984)] involves to thenext mode by mode.[Work supported by theAdvanced Surveillance experimentationwith a cutoff depthfor an artificialhomogeneous half- andPrediction System (ASAPS) Program of the Spaceand Naval Warfare space.For a mediumcomposed of homogeneouslayers, it is shownhow SystemsCommand (SPAWAR, PMW 181-14).] efficientcomputations are obtainedby writing the propagatormatrices 3353 J. Acoust. Sec. Am., Vol. 96, No. 5, Pt. 2, November 1994 128th Meeting: Acoustical Society of America 3353 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp involvedas productsof sparsematrices, which are appliedin sequence. mericalissues such as stiffness,we considerseveral nonseparable, range- Numericalstability can be achievedwithout artificially splitting thick ho- dependentducts with knownpiecewise analytic ray solutions.Results ob- mogeneouslayers. tainedfrom a shootingmethod and from Fermat'sprinciple for several suchducts are presented and discussed. [Work supported by ONR.] 4:00 4:30 5pUWll. A time-dependentsolution of a wave traversinga wedge 5pUWI3. The acousticwave equationas a finite difference. Michael by a finite length ping ray trace technique. Elmer White (Naval Res. Lab., Stennis Space Center, MS and 130 Moonraker Dr., Slidell, LA L. Oelze (Dept.of Phys.,Harding Univ., 900 EastCtr., Searcy,AR 72149-0001) 70458) A techniquehas been developedwhich demonstratesthat an acoustic The classicalwave equation used to describeacoustic phenomena was wave can be simulatedusing modifiedray trace theory for acousticmod- convertedto a finitedifference equation. This was done by constraininga soundpacket to be in a box of finitelength. By usingcertain mathematical eling in shallowwater. The resultingtime-dependent wave and the trans- missionloss data closely compares to that benchmarkerin the PE Work- techniques,recursion relations were found which enabled the amplitude of shopII Proceedingsof theSecond Parabolic Equation Workshop published soundto bemeasured at everypoint in thebox. This form of theequation is usefulin modelingcertain acoustic phenomena. The finite difference in May 1993,edited by S. A. Chin-Bing,D. B. King,J. A. Davis,and R. equationis especiallyuseful in calculatingwave reflection/transmission B. Evans.The solutionapproximating test case 2, a range-dependenten- vironment demonstrates forward and backscatter characteristics which phenomena.The classicalway of calculatingreflection/transmission was by calculatinga separatewave for eachreflected or transmittedwave. The agreewith bothPE and normal-modetheory in its behaviorpatterns. A VCR compositeof time imagesgenerated by the code •a,•G.F will be finitedifference equation method cancels the needfor manydifferent wavesand encompassesall interferencefrom thesewaves. shownwhich demonstrates the sound wave pattern as it traversesa wedge. Transmissionloss data are comparedto PE generatedTL to verify its 4:45 accuracy. 5pUW14. Time.domain propagationof signals in a strongly 4:15 refractive shallow-waterwaveguide and the extraction of ocean properties.N.A. Sidorovskaia(Dept. of Phys.,Univ. of New Orleans, 5pUW12. Finding eigenrays in environmentsprone to numerical NewOrleans, LA), A.I. Khil'Ko (RussianAcademy of Science,Nizshy instabilityand chaosby directlyoptimizing the traveltime integral. Novgorod603600, Russia), and M.F. Werby (NavalRes. Lab., Stennis Martin A. Mazur and KennethE. Gilbert (Appl. Res. Lab. and the SpaceCenter, MS) GraduateProg. in Acoust.,Penn State Univ., P.O. Box 30, StateCollege, PA 16804) The complexpressure from a pointsource is calculatedover the fre- quencyrange between 1 and5 kHz in stepsof 0.2 Hz asa functionof depth In classicalray tracing,eigemays are determinedby a "shooting" andrange for a strongly'ducted shallow-water waveguide. The waveguide approachwhereby the launchangles of rays are varieduntil the rays in- is composedof an80-m water column over a fluidhalf-space defined by a tersectthe receiver.In nonseparablerange-dependent environments, the compressionalvelocity of 1650 m/sand a densityof 1.6 relativeto water. ray paths computedby conventionalmethods are sometimeschaotic, Attenuationin thebottom is 0.25 dB/k. The velocityin thewater column therebyputting a fundamentallimit on theaccuracy of ray tracing.Previ- variesfrom 1540 at thesurface to 1513m/s at thebottom where a pro- ousresearchers [M.D. Collinsand W. A. Kuperman,"Overcoming ray nouncedgradient exists between 30 and60 m, withthe remaining regions chaos,"J. Acoust.Soc. Am. 95, 3167-3170(1994)] have suggested that beingweakly dependent on depth.A seriesof time-domaincalculations are ray chaoscan be overcomeby recastingthe problem in termsof Fermat's carriedout from the stored frequency data for pulses in termsof (1) pulse principleof minimumpropagation time. The problem then becomes ame- widths,(2) centralfrequency, (3) depthof detection,and (4) rangeof nableto so-called"direct methods" of optimizationtheory. For thespe- detection.The central notion is thatthe pulse amplitude is stronglycorre- cializedduct investigated by Collinsand Kuperman we haveeasily found latedwith depthdue to ductingeffects. Further, pulse widths and the eigenraysusing a simpleRayleigh-Ritz method for directlyminimizing principlearrival time adds more information on oceanproperties such as the travel time integral.The structureof the ray equationsfor the duct thevelocity profile and some aspect of seafloorgeoacoustic characteristics. suggests,however, that the numericalinstability may actuallybe due to Unambiguoussystematics that suggest a tooluseful for extractionof ocean "stiffness"rather than chaos. To investigatechaos independently of nu- dataare reported. [Work sponsored by ONR.] 33•1 J.Acoust. Soc. Am., Vol. 96, No. 5, Pt.2, November1994 128thMeeting: Acoustical Society ofAmerica 3354 Downloaded 27 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp