Comparison of Procedures for Determination of Acoustic Nonlinearity of Some Inhomogeneous Materials

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Comparison of procedures for determination of acoustic nonlinearity of some inhomogeneous materials

Jensen, Leif Bjørnø

Published in: Acoustical Society of America. Journal

Link to article, DOI: 10.1121/1.2020879

Publication date: 1983

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Citation (APA): Jensen, L. B. (1983). Comparison of procedures for determination of acoustic nonlinearity of some inhomogeneous materials. Acoustical Society of America. Journal, 74(S1), S27-S27. DOI: 10.1121/1.2020879

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PROGRAM OF

The 106thMeeting of the AcousticalSociety of America

Town and CountryHotel © San Diego, California © 7-11 November1983

TUESDAY MORNING, 8 NOVEMBER 1983 SENATE/COMMITTEEROOMS, 8:30 A.M. TO 12:10P.M.

Session A. Underwater Acoustics: Arctic Acoustics I

William Mosely,Chairman Naval ResearchLaboratory, Washington, DC 20375

Chairman's Introductions8:30

Invited Papers

8:35

A1. Bottom-interactingacoustic signais in the Arctic channel:Long-range propagation. Henry W. Kutschale andTai Lee(Lamont-Doherty Geological Observatory of ColumbiaUniversity, Palisades, NY 10964) Hydroacousticsignals from underwaterexplosions that havepropagated over the Arctic abyssalplains commonlydisplay marked frequency dispersion in pulsesthat arebottom-interacting and that arriveafter the $OFAR signal.In theinfrasonic band of 2 to 20 Hz, the temporaldispersion for eachpulse that has interacted withthe fiat bottom of theplain can be nearly as strong as that observed in the$OFAR signalfor thefirst mode. However,the bottom-interactingpulses correspond to a coherentsummation of manyhigher-order normal modesin a channelbounded above by theocean surface and below by theupper 400 m of thebottom sediments, wherethe velocityincreases with depth.Using normal-mode theory and the Multiple ScatteringPulse Fast Field Program(MSPFFP), we haveanalyzed the dispersionand pulseshapes and havederived the acoustic propertiesof thebottom in the Pole,Barents, and Mendeleyev Abyssal Plains. The principalproperties of the bottomcontrolling the propagationare compressionalvelocity, density, and attenuation.In contrast,the ice layerhas a negligibleeffect on the dispersionof the observedwaves. The effecton pulsecompression of this frequencydispersion of the bottom-interactingsignals was simulated numerically, using predistorted wave- formsmatched to thedispersion of the SOFAR channelat specifiedranges.

9:00

A2. Ambientnoi•e in thecentral Arctic Ocean. Ira Dyer (Departmentof OceanEngineering, Massachusetts Instituteof Technology,Cambridge, MA 02139) Underwaterambient noise has been measured in thecentral Arctic Ocean on three separate occasions with theuse of a horizontaland a verticalarray. These data help to identifyvarious noise mechanisms. Of principal interestis noise caused by variousice cracking events which depend upon stress levels in theice and which seem to havevarying temporal and spectral characteristics. I review these mechanisms and show how the data relate to them.While spatial analyses have been carried out only at verylow frequencies, spectral analyses cover the rangefrom I to 10000 Hz. In this frequencyrange noise mechanisms other than packice are sometimes important,such as wind-generated noise and earthquakenoise. [Work supportedby ONR.]

9:25

A3. Seismic/acousticpropagation in the Arctic Ocean.Arthur H Baggeroerand GregoryL. Duckworth (Departmentsof Oceanand ElectricalEngineering, Massachusetts Institute of Technology,Cambridge, MA 02139}

During the FRAM II and FRAM IV experimentsin the Pole AbyssalPlain and the BarentsAbyssal Plain of the Arctic Ocean24 channelhydrophone arrays approximately I km X I km in extentwere used to record digitallyboth seismic refraction and long-range acoustic propagation data. From these data the velocity versus depthfunction for the seismic structure along the FRAM II andFRAM IV drift trackswere estimated by high- resolutionvelocity spectral analysis and tau-slownessmigration methods. These indicate oceanic layers 2 and 3, but they are relatively thin. These techniqueswere also usedto identify internal and surface-reflected

Sl J. Acoust.Soc. Am.Suppl. 1, Vol. 74, Fall 1983 108thMeeting: Acoustical Society of America multipathsas well as converted shear paths to obtaina detailedcharacterization of the seismic propagation. Thelong-range acoustic signals contained strong modal components and bottom interacting ones. Velocity spectraand autoregressive algorithms resolved the dispersive properties ofthe phase and group velocity of each mode.These were usedto estimatethe water columnsound velocity profile with an inversionalgorithm. DuringFRAM II thebottom interactions lasted up to 80s long and contained as much energy as the low-order modesat low frequencies.These signals were used to estimatethe shallowvelocity versus depth structure. DuringFRAM IV thedispersion characteristics ofthe low-order modes changed slightly. In contrast,virtually no bottom-interactingenergy was observed suggesting strong scattering of the deeppaths by an intervening midoceanicridge. [Work supportedby ONR Arctic ProgramOffice.]

A4. TRISTEN/FRAM IV ew spatial eoberenceand temporal stability. F. R. DiNspoll, R. Nielsen, D. Potter(Naval UnderwaterSystems Center, New London,CT 06320),and P. L. Stocklin(Analysis and Technology,Inc., N. Stonington,CT 06359)

The TRISTEN-82/FRAM IV experimentwas a multifacetedexperiment investigating acoustics in the Arctic. This paper focuseson the spatial coherenceand temporal (frequency)stability of acousticsignals transmittedand receivedbetween fixed ice camps separated by approximately130 nmi. A high-powered,low- frequency(NUSC HLF-3 Arctic)hydroaroustic source transmitted stable cw tonesof I h or moreat various frequenciesfrom 5 to 200Hz duringApril 1982.These signals were received on an X-shapedarray having an apertureof 1200m on eachleg. The armywas operated by theMassachusetts Institute of Technologyand the Wood Hole OceanographicInstitute. The spatialcoherence, both broadsideand end-fireto the sourcewere foundfrom normalizedsensor pair crosscorrelation, corrected for signal-to-noiseratio. Total and 3-rib down receivedsignal bandwidths were found using complex demodulation and FFF with a resolutionto a fractionof mHz, followedby cumulativeenergy analysis in the frequencydomain. The experimentalsetup data, analysis procedures,and resultswill be presented.[Work sponsoredby the Officeof Naval Research,Code 425-AR.]

10:15

AS.Arctic data collection the easy way--Data buoys.Beanmont M. Buck(Polar Research Laboratory, Inc., 123 SantaBarbara Street, Santa Barbara, CA 93101)

This paperpresents a reviewof developmentaland operationaluse of Arctic data buoys.There are many problemsinvolved with aircraftand icebreakerlogistics for scientificsupport in the Arctic. Mannedresearch stationson seaice are expensive,self-contaminating in termsof acousticand electromagneticnoise, and generallylimited to a 40- to 50-dayperiod in thespringtime. Autonomous data buoys, on the other hand, do not sufferthose limitations. These devices can be installedby parsdrop,aircraft ice-landing,submarine, or ice- breakerin almostany geographic area of the ArcticOcean, peripheral seas, and marginal sea ice zones to collect andreport data over all seasons.There are restrictions, of course,as to what can be accomplished automatically withina smallbuoy hull, andalmost all Arctic buoys,so far, havebeen mechanically passive. Recent advances in low-powermicroprocessors and memories enable considerable increases in theextensive in-buoy processing neededfor data compression to aceomodate the limited capacities of polarorbiting scientific satellites. [Work supportedby U.S. Navy andNOAA.]

ContributedPapers

10:40 A my-theoreticmodel is advancedto describethe averagereverbera- tion intensitieswithin an Arctic channelbounded by a pack-icesurface A6. Normal mode and ray equivalencein the Arctic sound channel. and an upward-refractingsound-speed profile in the presenceof pressure RobertH. Mellen {B-K Dynamics,Inc., 247 ShawStreet, New London, ridgescattering. The surfaceis assumedrandom and a phenomenological • 06320) modelbased on Kirchoff assumptionsin the high-frequencylimit is de- Effectsof upwardrefraction combined with scatteringby the rough rived.Relevant parameters are estimated from data supplied by Chapman iceinterface result in a dispersivesound channel capable of propagating and Scottusing a curve-fitroutine. Ridges are modeledas inverted cones, only very low frequenciesto long range.Because only a few modesare the surfacesof whichare also assumed random. This simplifyinggeomet- involved,normal mode theory is appropriate.However, surface-scatter ric assumptionallows for a highlytractable technique. Forward as well as modelsare usuallybased on plane-waveapproximations for which ray backscatteredgeometries are treated with no assumptionsregarding theory is most useful.The two approachesare simplycombined in the source/receiverrange or depth and ridge location or draft. Applications impulse-responsemethod. Application of thismethod to thepropagation to sonarreceiver performance will be discussedin a companionpaper. of transientsand continuous wave signals is discussed.Removal of disper- [Work supportedby ONR.] siveeffects by deconvolutionto increasedata rate is alsoconsidered in viewof theextreme temporal stability of thechannel. [Work supported by 11:10 ONR and NUSC.] Ag. Sonar receiver performance models for the arctic channel in the presenceof ridge scattering.Garry M. Jacynaand Alan J. Friedman 10:55 (PlanningSystems Inc., McLean, VA 22102)

A7. Reverberationmodel of the arctic channel in the presenceof ridge A genericclass of sonarreceivers are modeledin an attemptto de- scattering.Garry M. Jacynaand Alan 1. Friedman{Planning Systems scribeaverage receiver performance in the Arctic channel.A ray-theore- Inc., McLean, VA 22102} tic model,discussed in a companionpaper, describes the averagereverber-

S2 J. Acoust.Soc. Am. Suppl.1, Vol. 74, Fall 1983 106th Meeting:Acoustical Society of America S2 ationintensities within an Arctic channel in thepresence of pressureridge campswere negligible during the transmissionperiods and hencethe re- scattering.Receiver performance isevaluated in termsof signal detectabi- sultsapply to transmissionbetween essentially fixed stations. lityas a functionof range,ridge location, and source/receiver depth. The modelsare extremelygeneral in that arbitrarypulse shapes and sensor locationsare allowed. As an illustration,two pulseshapes are consid- 11:40 ered--a transientand a CTFM pulse.Their effecton receiverperfor- manceis dependent on the source/receiver geometry as well as ridge loca- A10. Ultrasonicreflection measurements of floatingice. Neal G. Brower tion. In general,however, the longerCTFM pulseoften leadsto a (AppliedPhysics Laboratory, Johns Hopkins University,Laurel, MD reverberation-limitedcondition as a resultof surfaceas well as pressure 20702), Kin W. Ng, and Walter G. Mayer (Departmentof Physics, ridgescattering. [Work supportedby ONR.] GeorgetownUniversity, Washington,DC 20057) An experimentalinvestigation of reflectionof ultrasonic,bounded 11:25 beamsfrom floatingice has been conducted. Ultrasonic frequencies and icethicknesses corresponding to frequencythicknesses of between2 and 5 A9.Depth dependence of the temporai characteristics of cw propagation mm.MHz are considered.Nonspecular reflection profiles are obtained in theArctic Ocean. G. R. Giellis,T. C. Yang,and C. W. Votaw(Code usingschlieren techniques. These nonspecular profiles are comparedto 5123,Naval Research Laboratory, Washington, DC 20375I theoreticalprofiles calculated for water/iceplate/air systems.[Work sup- Previouswork by P. Mikhalevsky[J. Acoust. Sec. Am. 70, 1717-1722 portedby ONR.] (1981)] investigated the temporal characteristics ofcw signals propagating in theArctic Ocean. The previous work was limited to receivers at a depth of 91 m. In thispaper, the temporal characteristics will beextended to 28 11:55 hydrophonesin a verticalarray with depthsfrom 30 to 960 m. The data All. Acousticscattering from Arctic sea-iceridges using high-angie PE. weretaken during the FRAM IV experimentin April 1982.The signals Robert R. Greene(Science Applications, Inc., 8400 WestparkDrive, weregenerated at the Tristen ice campand receivedat the FRAM IV ice McLean VA 22101) camplocated north of Spitzbergen.The rangeof approximately275 km wasover the Mid-OceanRidge; the average water depth along the path Long-rangepropagation loss runs with thehigh-angle PE modelindi- was3000 m. Mostof thedata examined are at a highsignal-to-noise ratio catethat scatteringof soundinto the oceanbottom by sea-iceroughness (> 10 dB• which makesit possibleto studythe temporalfluctuation and can accountfor the frequencydependence of transmissionloss in the the statisticsof the cw signalsat differentdepths. By employinga mode Arctic.But differences between the slopes of thedata and predicted trans- filteringtechnique, the temporal dependence of theamplitude and phase missionloss curves suggest the presence of anadditional loss mechanism of the lowestorder mode has been investigated. The drift ratesof the ice in the ice.

TUESDAY MORNING, 8 NOVEMBER 1983 CALIFORNIA ROOM, 9:00 A.M. TO 12:00 NOON

Session B. Noise I: Use and Misuse of the FFF

John C. Burgess,Chairman Departmentof MechanicalEngineering, University of Hawaii, 2540 Dole Street,Honolulu, Hawaii 96822

Chairman's Introduction--9:00

Invited Papers

9:05

B1. Digital signalprocessing for soundand vibrationanalysis: A tutorial. JohnC. Burgess(Department of MechanicalEngineering, University of Hawaii, 2540 Dole Street,Honolulu, HI 96822)

The literature on digital signalprocessing is basedon four kinds of transform:Fourier transform(leT), z-transform,Fourier series, and discreteFourier transform(Dl:q•). Digital implementationuses only the DI:rT, usuallyin theform of an FFT algorithm.Some popular texts attempt to describedigital results by usinganalog (usuallyFT) analysis.Some have presented analytical results for infinitelength random signals and thenused illustrationsbased on finite lengthperiodic signals. What "windows"do and their differenteffects on random and periodicsignals seldom are clearlyidentified. There are two implementationsof the DFT that differby a constantfactor. Fast convolution and correlation analyses require special handling to avoid"circular" effects. The DIeT treatseach finite lengthsample from a randomsignal as if it werea samplefrom a deterministic signal.The purposeof this tutorialis to illuminatethese and other potentiallytroublesome aspects of digital signalprocessing pertinent to applicationsin soundand vibrationanalysis.

9:35

B2. Noise source identification by coherence and acoustical methods using FF'Y analyzers. Thomas H. Hodgson(Center for Soundand Vibration, North Carolina StateUniversity, Raleigh, NC 27650) The practicalunderstanding of the two-channelFFT spectrumanalyzer as used in noisesource identification will be addressed.In particular,the measurementof the coherencefunction and the acousticintensity, the

$3 d. Acoust.Sec. Am. Suppl. 1, VoL 74, Fall 1983 106th Meeting:Acoustical Society of America S3 latterby bothtwo-microphone and surface methods, will be described.Problems related to amplitudeand phaseinformation and the design of mostanalyzers as they relate to Fouriertransform theory or electrical networkpractice will be discussed.Several case studies of noisesource. identification measurement will be presentedin orderto demonstratesome of thepoints related to FFT analyzeruse described in thepaper. Both steady-stateand impact noise problems will beconsidered with referenceto causesof possibleerrors.

9:55

B3. Field experiencewith soundand vibrationmeasurements using an FF'Y analyzer. Frank H. Brittsin {BechtelResearch and Engineering,P.O. Box3965, San Francisco, CA 94119} The theoryupon which FFT analyzersare based promises a very powerful and useful measurement tool. In thefield, a varietyof practicaldifficulties often affect the ability to obtainvalid results using an FFT analyzer. Thesedifficulties fall into fivccategories: {!) inadequateknowledge on the part of the user,{2} details of the analyzeras implementedby the manufacturers,{3) bugsin the hardwareand softwareof the analyzer,{4) conditionsunder which measurements are made{including the individualcharacteristics of the equipment testedand the backgroundvibration), and {5)ability of thc userto interpretdata from the analyzer.Each of thesefive categories isdiscussed, with emphasis on two-channel measurement applications. Practical cxamplcs of field problemsencountered and methodsused to overcomethem are discussed.

10:15

B4. Statusof standardson digitalsystems for soundand v•ration analysis.Tony F.W. EmbletonIDivision of Physics,National Research Council, Ottawa, Ontario KIA OSI, Canada) ExistingANSI lAmericanNational Standards Institute) standards deal primarily with analogacoustical instrumentsand their use--following traditional thinking and procedures of acousticians.They are relevant to the analogparts of a digitalsignal processing system such as the signalitself Itime and frequency characteristics),transduction (directionality, linearity, frequencyresponse of microphonesor vibrationpick-ups), and output(preferred frequencies, reference quantifies). They are alsorelevant to digitalcomponents that mimic closelythe behaviorof analogdevices, e.g., filters that receivesignals continuously. The next revisionof S1.1 I will explicitlyinclude specifications for the performanceof bothanalog and digital filters. The IEC 0nterna- tional ElectrotechnicalCommission• acoustical standards similarly relate to analoginstruments and their use. The nextseveral years should see progress in the developmentof standardsfor digitalacoustical iustrumenta- tion, but beforethis can happenacousticians must recognizeand widelydiscuss the technicalproblems that exist.General consensusshould be reachedon many factors,one of the most fundamentalis the possible methodsof achievinga desireddegree of accuracyfor a givenkind of acousticalsignal. Standards written prematurelyrisk biasingmeasurement procedures, and instrumentationto meetthese needs, in what may be less-than-optimumdirections.

10'.35 to 11:00

Panel Discussion

ContributedPapers

11:00 Other methodshave beenevolved, but theseusually rely on two micro- phonemeasurements. The single microphone system reported here utilizes Bfi. Amplitude calibration of an FFT analyzer. JosephPope {Bruel & the incidentand reflectedpulse in a circularimpedance tube. The pulseis Kjaer Instruments,Inc., 185Forest Street, Marlborough, MA 01752} generatedby a suitablydamped loudspeaker driven by a low-frequency When usedfor frequencyanalysis, an FFT analyzerproduces a line squarewave. A two-channelFast FourierTransform. analyzer captures spectrumon the amplitude-frequencyplane. Each spectrum line repre- the pressure-timehistory. The signalis then conditionedleaving only sentsthe outputof a filter centeredat the frequencyassociated with the replicatesof theincident and the reflected pulses suitably shifted in timeto line,the shapeof the filter beingdetermined by the effectivetime window simulateconditions at the samplesurface. Using the variousfeatures of appliedto the databeing analyzed. While it is generallyrecognized that modernFFT analyzers,the reflection(absorption) coefiieient as well as the useof an explicitwindow function is often desirablese.g., to control the complexvalued impedance are readilyavailable from a singlemea- spectral"!eakage"--many FFT usersseem unaware that useof a windom surement.At presentthe usable frequency range is 5 kHz. [Worksupport- impliesa compensatorycalibration adjustment that is dependent upon the ed by the NaturalScience and Engineering Council, Canada.] characterof thedata and theobjective of theanalysis. Effective filter shapes for rectangular,Harming, flat top, and Kaiser-Besselwindows are dis- 11:30 cussedalong with the conceptof filter amplitude responseand effective noisebandwidth. ApprOpriate calibration for rms,power, power spectral BY. Use and mistmeof an FFT analyzer for octave-band and one-third density,and energy spectral density spectra is explained. octave-bandanalysis. Richard C. Sohaney(Bruel & Kjaer Instruments, Inc., ! 85 ForestStreet, Marlborough, MA 01752) 11:15 An FFT analyzeris often usedas a "real time analyzer"to perform octave-bandand one-thirdoctave-band analyses. The limitationsand as- B6. Acoustic impedancemeasurement v'a FF'r. Werner G. Richarz (Institute for AerospaceStudies, University of Toronto, 4925 DufFerin sumptionswhich the filter synthesizingtechnique imposes on the data Street,Downsview, Ontario, Canada) signalare discussed.A methodfor synthesizingANSI ClassII octave- bandand ClassIII one-thirdoctave-band filters using an FFT analyzeris The measurementof acousticimpedance of acousticmaterials and explainedwith emphasison the shortcomingsof synthesizedfilters. networksoften requires a ratherlaborious impedance tube measurement. ampleanalyses of varioussignals are performed with conventionalANSI

84 d. Acoust.So(:. Am. Suppl.1, VoL 74, Fall 1983 106th Meeting:Acouslical Society of America S4, ClassIII one-thirdoctave-band filters and an FI• analyzerto demon- FFT devicesoften include a data smoothingcapability that is based stratecorrect and incorrect use of the synthesizedfilter method. uponaveraging over a selectednumber of adjacentpoints in a dataarray. Averagingtime domain data in thisway is equivalent to low-passfiltering the data. The resultinginaccuracies associated with frequencydomain 11:45 representationsof the averaged data are examined. Predicted and experi- mentalresults are presentedfor the FF"r'sof averagedsinusoidal, period- 1•. Dam averagingand FFr devices.David K. Holger (Departmentof ic, and filtered random waveforms.The effectsof sampleinterval and EngineeringScience and Mechanics, 214 ERI Bldg., Iowa State numberof averagingpoints on the equivalentfilter characteristics of the University,Amm, IA 50011) averagingprocess are discussed.

TUESDAY MORNING, 8 NOVEMBER 1983 COUNCIL/CHAMBER ROOMS, 9:00 TO 10:40 A.M.

SessionC. Engineering AcousticsI and Architectural AcousticsI: Teleconferencing

James E. West, Chairman Bell Laboratories,Murray Hill, New Jersey07974

Chairman's Introduction--9:00

Invited Papers

9:05

CI. Acousticsof teleconferencing.Chris Stockbridge(American Bell Inc., E.D.&D., Room4G-514, Holmdel, NJ 07733) Room acousticsis an elementof teleconferencingtoo often neglected.Ideally, the room shouldnot be symmetricaland the walls should be nonparallel, covered irregularly with sound scattering and noise absorbing panels.At thevery least, a placefor teleconferencing must be quiet and not reverberant. Technical specification of varioussizes of desirableacoustical spaces which match both people's behavior and equipment constraints will beset forth in thistalk. Equipmentand techniques will bediscussed which select acoustics for a naturalfeel withinthe room while generating signals that create clear and recognizable voice sounds when heard at remote location(s).These include phased array directional microphones, carefully positioned loudspeakers, simple acousticabsorption, and for themore sophisticated, nonparallel walls and irregular ceiling clouds. The real challengeis to implementthis technology in an aestheticallypleasing fashion, tailored and matchedto the cultureof theexpected user population. A varietyof teleconferencingrooms will bepresented in photographs, showingevolution in thedesign of roomsfor audio,audiographic, and full motionvideo teleconferencing.

9:30

C2. The humanengineering of a newteleconferencing service. Daryl J. Eigen(Bell Laboratories,Naperville- WheatonRoad, Naperville,IL 60566I The BellSystem is developing a new network teleconferencing service. This service enables the customer to setup a conferencewith or withoutan operator,and it incorporatesstate-of-the-art signal processing techno- logyto enhanceaudio quality. The humanengineering of thisnew service concentrated on characterizingthe customer,optimizing the perceived audio quality, and making the conference setup procedures easy to use and errorfree. A coordinatedseries of interviews,surveys, laboratory studies, and field studies was implemented to increasecustomer satisfaction, performance, and usage. This sequence of testingis culminated in a Controlled ProductTest, which is a dressrehearsal of a newservice, using Bell Systememployees as the firstcustomers. The CPT startedon 7 February1983 in selectedsites in SanDiego, Los Angeles, and San Francisco with two bridgeslocated in LosAngeles. The CPT has since been expanded to additionalsites in 12states with four more bridges,two in WhitePlains, New York and two in Chicago,Illinois. This geographic diversity provides the opportunityfor large calling volumes and a widerange of conference configurations. Over 2000 calls have been placedthus far, allowingthe conference setup procedures to besimplified and perceived audio quality to be improved.

ContributedPapers

9:55 but only recently has it been appreciatedthat the directivity of micro- C.3. The Quorum TM teleconferencingmicrophone. James H. Snyder phonearrays makes them superior to conventionalmicrophones in many audioapplications as well. In this paperwe describea particularmicro- (AmericanBell, Holmdel,NJ 07733) phonearray, the Quorum TM teleconferencingmicrophone, whose direc- Arraysof microphoneshave long been used in underwateracoustics, tivity is achievedby the nonuniformspacing of the transducers.We pres-

$S J. Acoust.Soc. Am. Suppl.1, VoL 74, Fall 1983 106thMeeting: Acoustical Society of America $5 entequations for thearray sensitivity assuming plane and spherical wave 10:2S radiation,and comparethese results with measurements. CS.An sentratiodirection finder. C.H. Coker(Bell Laboratories, Murray Hill, NJ 07974) and D. R. Fiseheli (Bell Laboratories,Holmdel, NJ 10:10 07733) CA. Conferencemicrophone with adjustabledirectivity. J. L. Flanagan and R. A. Kubli (AcousticsResearch Department, Bell Laboratories, A simpleprocedure is described for findingthe direction to the source Murray Hill, NJ 07974) of an acousticsignal--primarily the humanvoice. The method,in effect, constructsthe crosscorrelation of severelydistorted signals from two Designsare given for fixed-steeredline-array microphones suitable for microphones.The distortion,a combinationof time-domainprocessing teleconfereneeapplications.,The steering isarranged sothat the array can and digitallogic, is suchto givestrong preference to direct-pathearly be locatedout of line-of-sightof the conferees.The directivitypattern of arrivalsover reflectionsthat follow, and to producestreams of pulses the transducercan be selectedto giveeffective spatial coverage for a var- whosecross correlations can be computedvery simply. The methodhas iety of conferenceconditions. Additionally, the designsutilize acoustic beenimplemented as a combinationof customhardware, and a simple summationand anti-aliasingfiltering. They requireonly an inexpensive microprocessor.The implementationoperates in realtime (with •0.2-s electretelement as the transducer.Theoretical responses are calculated delay}and produces outputs to indicate either the azimuth angle, or inter- and plottedon an Apple II computer.A prototypemodel is fabricated, microphonedelay. Possible uses include self-aiming directional micro- and experimentalmeasurements, made under free-fieldconditions, are phones,automatic aiming or switchingof video cameras,and remote shownto comparesatisfactorily with the theoreticalresponses. identificationof talkersin nonvideoteleconferencing.

SessionD. ArchitecturalAcoustics II: The TechnicalCommittee on ArchitecturalAcoustics V. O. KnudsenDistinguished Lecture

SessionD moved to Thursday Afternoon, 10 November 1983 at 1:30 P.M.

TUESDAY MORNING, 8 NOVEMBER 1983 SUNRISE ROOM, 9:00 A.M. TO 12:05 P.M.

SessionE. PhysiologicalAcoustics I: Peripheral Systems

JosephE. Hind, Chairman Departmentof Neurophysiology,Medical ScienceBuilding, Universityof Wisconsin,Madison, Wisconsin53706

Chairman's IntFoductio•9:00

ContributedPapers

9.'05 The anatomyof the cochleaof six speciesof odontocetes,or toothed whales(Ph•,seter catadon, Grampus griseus, Lagenorhynchus albirostris, El. Comparativecochlear morphologyin echolocatingeetaeeans. D. Phocoenaphocoena, Tursiops truncatus, and Stene!!a !ongirostris)was R. Ketten,F. L. Starr,'• andD. Wartzok(Department of Immunology comparedusing conventional micrography and radiographictechniques and InfectiousDisease, John HopkinsMedical Institute,615 N. Wolfe includingedge enhancement x-ray, CT scan,magnification radiography, Street,Baltimore, M D 21205) and digitalsubtraction. These species were selected for differencesin fre-

S6 J. Acoust.Soc. Am. Suppl. 1, Vol. 74, Fall 1983 106thMeeting: Acoustical Society of America S6 quencyand patterningof normal and ultrasonicvocalizations in their linear modulationof this activity, allowingone to definesmall-signal lin- naturalenvironments. The cochleawere extracted post-mortem and pre- ear transferratios and to observetuning curvesfor suchaxons. Each servedby injection.Whole cochlea were first examined radiographically tuningcurve to date reflectsmultiple resonances, sometimes coalescing for species-specificdifferences in grossmorphology and topology,par- with no interveningantiresonances, sometimes separated by simpleantir- ticularlyfor angularchange of the scalaeand torsionof membranaland esonances.The latter typicallyare muchsharper than the resonanceson neuralcomponents. Specimens were then decaltitledand processedfor eitherside, indicating that they are not simplyconcomitants of additive SEM or thin sectionmicroscopy. Measurements obtained by bothmeth- parallelresonances. Phase lag typicallyincreases by two cyclesor more odsare presentedand the advantagesof the radiographictechniques dis- with increasingfrequency through the tuning range (roughly l0 to 200 cussed.The resultsare comparedwith the cetaceancochlear models of Hz), with abrupt half-cycledeclines through the antiresonances.Reso- Wcvcr[Wever et al., Proc.Natl. Acad. Sci.68, 2381-2385(1971)] and nantand antiresonant frequencies vary from axonto axon,usually lying Fleischer[G. Fleischer,J, Paleon.$0 •1), 133-152(1976)] and analyzed between.20and 120Hz. The amplitudesof peaktransfer ratios vary ap- accordingto the dimension-frequencycorrelation techniques of Green- proximatelyfrom 50 to 200 spikes/s per cm/s 2. At 100Hz, whereit occa- wood[D. D. Greenwood,J. Acoust.Soc. Am. 33, 1344-1356(1961)] and sionallyis found, the latter correspondsto approximatelyone spike/s Hinchcliffeand Pye JR. Hinchcliffeand A. Pye, Int. Audiol. 7, 259-288 responsefor whole-animaldisplacement of 10 pro. [Supportedby NSF (1968}].[Work supported by NSF.] al Also at RadiologyResearch Labora- Grant BNS-8005834.] tory, JohnsHopkins Hospital, Baltimore, MD 21205.

10:05 9:20 E5. Filter characteristics of low-frequency cochlear nerve fibers as E2.Three-dimensional directionalisensitivity ofgoldfish 8thnerve fibers. determinedby synchronyresponse pntterns to two-componentsignals. Richard Fay, Sberyl Coombs,and JosephBaumann (Parrely Hearing StevenGreenberg, C. Daniel Geisler, and L. Deng (Departmentof Institute, Loyola University of Chicago, 6525 N. Sheridan Road, Neurophysiology,University of Wisconsin,1300 University Avenue, Chicago,IL 60626) Madison,WI 53706) Three-dimensionalmaps of directionalsensitivity were constructed The tuningand filter characteristicsof cochlearnerve fibers, as con- for singlefibers of thesaccular, lagenar, and utricular nerves by measur- ventiallydetermined by stimulationwith single-componentsignals, are ingacceleration thresholds to sinusoidalmotion oriented along 40 axesin usuallyintensity level-dependent. Shifts in characteristicfrequency and threeorthogonal planes. Stimuli were generated by adding three mutually significantdeterioration of frequencyselectivity are often observed at su- perpendicularvibration inputs to a rigid cylindercontaining water (and pra-rate-saturationintensities. In the presentstudy relatively level-invar- the fish}.The phasesand amplitudesof the inputswere computedto iant estimatesof characteristicfrequency (CF) and frequencyselectivity achievelinear motion vectors with particularorientations, as determined wereobtained for low-frequency( < 3 kHz) cochlearfibers in the cat via by anaceelerometer array. Phase-locking was used to definea cell'saccel- stimulationwith two (equi-amplitude)-componentsignals. Characteristic erationsensitivity, and the po10rityof the response{the excitatory direc- frequencywas estimated by on-lineanalysis of the fiber'ssynchrony re- tionof motion).In general,the 3-D directionalsensitivity of cells(in dB} is sponsepattern to a two-componentsignal whose bandwidth was approxi- describedby a solidcomposed of two tangentspheroids, with an axisof mately10%-20% of the unit'sCF. Estimatesof fiberCF remainedrela- greatestsensitivity passing through their centers.In the saccule,these tively constantover a 60 to 80 dB range of intensities.Frequency axesare oriented primarily dorsal-ventrally with deviations from vertical selectivity(for a two-tonecomplex) was determined by settingeither the of up to 40'. Lagenarfibers show similar patterns but with greatervari- upperor thelower signal component equal to theunit CF andvarying the ationof orientation in themid-saggital plane. Utricular units show greater frequencyof the secondcomponent over an octaverange. Two-compo- variationin all planes.Any givenaxis of particlemotion is represented in nentsignals provide a considerablyhigher estimate of a fiber'sfrequency theprofile of responseacross arrays of fibersof differentorientation, and selectivitythan is commonlyobserved using single-component stimuli. is bestdefined by fibersoriented with a null planeparallel to the axisof [Researchsupported by NIH.] motion.[Supported by the NSF.]

10:20 9:35 E6. Behaviorof the I•ulse-numberdistribution for theneural spike train in E3. Whole-nerveresponse to tonebursts in the alligatorlizard. Robert the cat's auditory nerve. Malvin Carl Teich and ShyamM. Khanna G. Turner, Nell T. Shepard,and Donald W. Nielsen (Otological {Departmentsof ElectricalEngineering and Otolaryngology,Columbia ResearchLaboratories, Henry Ford Hospital,Detroit, MI 48202) University,New York, NY 10027) The peripheralauditory system of the alligatorlizard (Gerrhonotus Pulse-numberdistributions (PNDs) were recorded from primaryaf- multicarinatus)has been studied extensively; however, limited data are ferentfibers in the auditorynerve of the cat, usingstandard microelec- availablefor the whole-nerve(AP) response.Could the AP serveas a trodetechniques. Pure-tone and broadband-noise stimuli were used. The convenientmonitor of the conditionof the ear during experimentation? numberof neuralspikes (pulses) n wasmeasured in a setof contiguous AP responsesto toneburst acoustic stimuli of variousfrequencies were intervals,each of duration T seconds.The quantity.n variesfrom one recordedfrom the alligatorlizard and threemeasures using the AP re- interval to another. These data were then used to determine the PND, sponsewere obtained. (1) Averagedsuprathreshold AP responseswere whichis the probabilityp(n,T) of occurrenceof n spikesin the time T, relatedto primaryauditory nerve fiber activity. (2) AP thresholdswere versusthe number n. The estimatedmean and varianceofp(n,T} were comparedto single-unitthresholds. (3) AP excitatorytuning curves were obtained. Two different values of Twere used. We observe that the count comparedto single-unittuning curves. The goodagreement between AP mean-to-varianceratio R is relativelyconstant and independentof the responsesand single-unit data indicate that the AP is a usefultool for stimulusintensity. The PND readilyexhibits the existenceof spikepairs measuringthe physiologyof the peripheralauditory system in the alliga- in the underlyingpoint process for someunits. A studyof the scaledand tor lizard. unscaledpulse-interval distributions {PIDs), under conditions of sponta- neousfiring, demonstrates that the occurrences of neuralevents are some- 9:50 timesnot describableby a renewalprocess. [Work supportedby NIH Grant 2-R01-NS 03654.] FA. Linear gain and phase in seismicneurons. Edwin R. Lewis •ElectronicsResearch Laboratory, University of California, Berkeley, CA 94720 I 10:35 In nearlyquiescent seismic environments, many bullfrog (Rana cates- E7. Acoustic responseproperties of units in dorsal cochlearnucleus of beiana}saccular afferent axons exhibit ongoing activity, typically ranging unanesthetized,decerebrate gerbil. Herbert F. Voigt (Departmentsof from 10 to 80 spikes/s.Low-level vibration of thewhole animal [see H. BiomedicalEngineering and Otolaryngology,Boston University, 110 Koyamaet al., BrainRes. 2S0, 168-172(19821 for methods]produces CummingtonStreet, Boston, MA 02215)

_e7 J.Acoust. Soc. Am. Suppl. 1, Vol. 74, Fall 1983 106thMeeting: Acoustical Society ofAmerica S7 Singleunit recordingswere madein the dorsalcochlcar nucleus Electrophysiologicaland psychophysicalmeasures of thresholdas a (DCN}of unanesthetized,decerebrate Mongolian gerbils. Access to the functionof sinusoidalstimulus frequency deviate from those predicted by gerbilDCN wasobtained using a newlydescribed approach [Frisina et aL, Hill's excitationmodel. Severalmembrane models (e.g., the Franken- HearingRes. 6, 259(1982}]. Single units, recorded with 3M NaCI filled hauser-Huxleymodel and the Hodgkin-Huxleymodel) suggest possible micropipetteelectrodes (20 Mohm typical},were classifiedinto three mechanismsresponsible for thedeviations. For example,by usinga modi- types{II, III, or IV} basedon theirresponses to bestfrequency (BF} tone fiedHodgkin-Huxley model more accurate threshold "predictions" were bumtsand their rates of spontaneousdischarges. Type II unitshave little obtainedover the 50-500-Hz frequencyrange. The Hodgkin-Huxlcy or nospontaneous activity and are excited by BF tonesat all levelsabove modelwas modified by increasingthe sodiuminactivation rate constant, threshold.Type III unitsare alsoexcited by BF tonesat all levelsabove beta-h,by a factor of 4. This modificationcaused the hyperpolarizing threshold,but havespontaneous activity ratesthat exceed2.5 spikes/s. phaseof thestimulus to becomemore effective at increasingthe simulated Type IV unitsare excitedover a narrowrange of soundlevels near BF membrane'sexcitability to thesubsequent depolarizing phase, particular- threshold,but are stronglyinhibited at higherlevels. Thus all unit types ly whenthe hyperpolarizingphase was on the orderof l0 msin duration. foundin the unanestbetized,decerebrate cat DCN [Youngand Brownell, Consistentwith thismodel, recordings in the AVCN of eat indicatethat a 1. Neurophysiol.39, 282 {1976};Young and Voigt, HearingRes. 6, 153 hyperpolarizingelectrical stimulus applied to the auditorynerve signifi- 0982}]are also found in gerbil.[Work supported by NIH.] cantly increasesthe excitabilityof the nerveto a depolarizingstimulus that follows.[Work supportedby NIH.]

10:50

E8. Temporal-neural-responsecorrelates of pitch-intensity effects and diplacusis. K. Jones, A. Tubis (Department of Physics, Purdue University,West Lafayette,IN 47907},and E. M. Burns(Department of Audiologyand SpeechSciences, Purdue University, West Lafayette,IN 11:35 47907) E11. Directional sensitivityof auditory neuronsin the superiorcolliculus Pure-tonepitch anomalies such as pitch-intensity effects and diplacu- of the bat (Myotis !ucifugus}.Donald Wong (Department of Biology, sishave been traditionally considered as evidence against temporal theor- WashingtonUniversity, St. Louis,MO 63130} iesof pitch.These phenomena, however, may at leastin part, be correlated The directionalsensitivity of auditoryneurons in the deeplayers of the with stochasticmodel calculationsof VIIIth nerve firing probabilities. superiorcolliculus was examined in unanesthetizedbats stimulated in the Thesecalculations predict shifts in the peaksof the I$I histogramas a freefield with frequency-modulated (FM}sounds (100 to 40 kHz} mimick- functionof the intensityof acousticstimulation which are consistent with ' ing their naturalorientation sounds. The minimumthreshold of a unit averagehuman pitch-intensity data. The samemodels suggest a temporal wasfirst measuredwhen the soundwas presented directly in front of the basisfor somefeatures of central-processor-typealgorithms in complex- animal. Sounds 10, 30, and 50 dB above threshold were then delivered at tonepitch perception. They alsoaccount qualitatively for the frequency- every 10. azimuthfrom a hoop-mountedspeaker that rotatedalong the dependentdeviation from unity of the ratioof thefirst ISI histogrampeak horizontalplane from 80' ipsilateralto 80' contralateral.Many unitsex- to the stimulusperiod, as seenin ISI measurements.Physiological and hinted spatialselectivity to a soundsource that wasrestricted between 10' psyehophysicalmeasurements, and detailedneural model studies which ipsilateralto 20' contralateraland had an intensityI 0 dB abovethreshold. are designedto checkthe validity of thesepreliminary results, will be Soundof higherintensity was effective throughout the contralateralside described.[Work supportedby NIH Grant NS 15405and NSF Grant in driving theseneurons, although the relative responsemagnitude dif- BNS 8021529.] feredat the individualangles. Mapping experiments did not revealany systematicrepresentation ofbest azimuth in thismidbrain structure. Nev- 11:05 ertheless,faint echoesreturning from a targetalong a line near the bags flightpath provide directional cues necessary for accuratetarget localiza- E9. Implications of ear canal geometry for various acoustical tion. [Work supportedby NIH.] measurements.Michael R. Stinson (Division of Physics, National ResearchCouncil, Ottawa, CanadaKIA 0R6}

Recentwork hasdemonstrated that the geometry(size, shape} of the humancar canal leadsto a soundfield, at high frequencies,that varies within the canal in a complicatedfashion. In particular,the eardrum 11:50 terminatesthe ear canalat a rather sharpangle, and significantvariations of soundpressure (over 15 dB} ariseover the eardrumsurface above 10 El2. Suseeptibilityto intenseimpulses. G. Richard Price (U.S. Army kHz. The implicationsof theseobservations, as they apply to several Human EngineeringLaboratory, Aberdeen Proving Ground, MD 21005} aspectsof hearingresearch, will bediscussed, utilizing a three-dimension- and David J. Lim {Departmentof Otolaryngology,Ohio StateUniversity al horn equationapproach that hasbeen developed. Knowledge of the Collegeof Medicine,Columbus, OH 43210} soundpressure distribution within the ear canalis importantin the exten- sionof audiometryto highfrequencies, and for guidingthe development Pricehas advanced the view that susceptibilityto intenseimpulses of of hearingaids. Studies of auditoryprocesses that usea referencemicro- thetype produced by weaponsis a functionof a spectrallyrelated "critical phonein thecar canal become increasingly sensitive to microphoneloca- level"in the ear [J. AeoustSoc. Am. 73, 556-566(1983}; I. Acoust,Soc. tionas higher frequencies are used;estimates of theerrors of reproducibil- Am. Suppl.1 62, S95.(1977}].This viewresults in a majordisagreement ity aregiven. Present acoustic network models of the middleear assume a with all damagerisk criteria in usein the world by predictingthat for uniformsound pressure at the eardrum;possible ways of handlinga non- equalpeak pressures, rifle impulsesare morehazardous than cannonim- uniform pressuredistribution are discussed. pulses.A crucial experimentwas run usingboth earsof 57 catsto test this hypothesis[G. R. Price,J. Acoust.Soc. Am. Suppl.! 71, S79(I 982}].Two monthspost exposure, final electrophysiological measures were made and 11:20 the earswere perfused for histologicalprocessing. Histological measures involvingboth scanningelectron microscopy and serial sectioningand El0. Electrical stimulation of the auditory nerve: Membrane models lightmicroscopy (opposite ears of eachcat} can now be compared with the appliedto the interpretationof electrophysiologicaland psychophysical earlier electrophysiologicalmeasures. The two setsof histologicalmea- responses.M. White (Department of Otolaryngology, UCSF, San suresshow the samepicture and they in turn correlatewell with the elec- Francisco,CA 94143) trophysiologicalmeasures.

S8 J. Acoust.Soc. Am. Suppl. 1, Vol.74, Fall 1983 106thMeeting: Acoustical Society of America S8 TUESDAY MORNING, 8 NOVEMBER 1983 GOLDEN WEST ROOM, 9:00 TO 11:35A.M.

SessionF.PsychologiCal Acoustics I: Pattern Processing inSpace and Time

Lois L. Elliott, Chairman NorthwesternUniversity, 2299 SheridanRoad, Evanston,Illinois 60201

Chairman's Introduction---9:00

ContributedPapers

9.-O5 This paperdescribes a systemfor processingsohorant regions of speech,motivated by knowledgeof thehuman auditory system. The spec- Fl. Behavioralevidence for central codingof azimuth as a functionof tral representationis intendedto reflecta proposedmodel for human stimulusfrequency. Alan D. Musicant'j (Departmentsof Behavioral auditoryprocessing of speech,which takes advantage of synchronyin the Scienceand Surgery,University of Chicago,Chicago, IL 60637) nervefiring patterns to enhanceformant peaks. The auditorymodel is also In a previousreport to the Society[Musicant and Butler,J. Acoust. appliedto pitch extraction,and thusa temporalpitch ptxmessoris envi- Sec.Am. Suppl.! 72, S93 (1982}]we presenteddata on the orderlypro- sioned.The spectrumis derivedfrom the outputsof a setof linearfilters cressionof perceivedazimuth of narrowbands of noiseas a functionof with criticalbandwidths. Saturation and adaptation are incorporated for stimulusfrequency. The patternsthat resultedhave been called Spatial each filter independently.Each "spectral"coefficient is determinedby ReferentMaps (SRMs}.A recentexperiment suggests that theseSRMs weightingthe amplituderesponse at that frequency(corresponding to mustinvolve a centralmechanism for codinglocation in the horizontal meanfiring rate} by a measureof synchronyto thecenter frequency of the plane. In this experiment,stimuli consistedof !-kHz-wide noisebands filter. Pitch is derivedfrom a waveformgenerated by addingthe Iweight- with centerfrequency (CF} ranging from 4--14 kHz. Therewere 13 loud- ed) rectifiedfilter outputsacross the frequencydimension. The system speakersplaced 15' apart at locationsfrom 360' to 180• azimuth.Stimuli performanceis evaluatedby processingof a varietyof signals,including werepresented from only that loudspeakerlocated at 270ø . Subjects,lis- natural and syntheticspeech, and resultsare comparedwith other pro- teningmonaurally, responded with the loudspeakerposition from which cessingmethods and with knownpsychoacoustical data from thesetypes they perceivedthe soundas originating.SRMs were then constructed. ofstimuli.[Work supported in partby NINCDS andthe System Develop- Subjectsnext performed the same task, but nowlistened monaurally with ment Foundation.] the pinnacavity of the open car filled. The externalmeatus was open. Azimuthaljudgements of stimuluslocation were collected and compared to the data collected earlier. Correlations between the means of the azi- 9:50 muthaljudgements at eachfrequency for the two conditionsranged from F4. Effect of amplitudemodulation upon fusion of spectralcomponents. 0.81-0.97for sevensubjects. The highdegree of correlationsuggests that, Albert S. Bregman, Jack Abramson {Department of Psychology, at least for narrow bands of noise, a central mechanism must exist that McGill University, 1205 Doctor PenfieldAvenue, Montreal, Quebec, codesazimuthal sound source location as a functionof stimulusfrequen- Canada H3A IBI), and Christopher Darwin (Laboratory of cy. '•Prcsentaddress: Department of Neurophysioiogy,University of ExperimentalPsychology, Sussex University, Brighton, England} Wisconsin,Madison, Wl 53706. We studiedthe perceptual integration of twocomplex tones, each sent to both earsand formedby amplitudemodulation {AM) of a carrier fre- 9:20 quencyCF by a sinusoldwith modulationfrequency MF. Onetone always F2. Sidedhessand perceptionfor singleecho of someordinary sounds. had CF = ! 500 Hz and MF = 1(30Hz. The other had CFs around 500 Hz Terry S. Zacconeand Earl D. Schubert(Hearing and SpeechScience, and MFs around 1(30Hz. Both harmonicand inharmonicpartials, pro- StanfordUniversity, Stanford, CA 94305} ducedby AM, wereemployed. The methodinvolved studying the compe- tition betweentwo organizations:la} the fusionof the two tones,and (b} Nine differentsound-sample sequences ranging in temporalpredicta- thetendency of thehigher to bestripped out of themixture by a competing bilityfrom white noise to Englishspeech were recorded with a singleecho sequentialorganization. Fusion was bestwhen the both toneshad the delayedfrom zeroto 100ms. The soundswere recorded in the presenta- sameMF, evenwhen the resultingpartials did not form part of the same tion modesof menaural,dieboric, and mixedIoriginai to both cars,de- harmonicseries. Fusion was enhanced when AM appliedto thetwo tones layedin one}.The singlerepetition intensity was equal to, and3 and6 dB wasin phase.Results relate to the perceptualseparation of simultaneous greaterthan, that of the originalsound. Subjects were asked to indicate voicesand favor a theory in which basilarmembrane outputs that are whenthe echowas perceivedand, in separatetests, on whichside they amplitudemodulated by the sameglottal pulsewill be allocatedto the perceivedthe sound.In general,the abilityof the subjectsto choosethe same voice. sideof theleading signal diminished as the repetition delay increased past 20 ms.They wereexpected to perceivetemporal order rather than sided- hessas the delaybecame longer than 20 ms. Even for soundswith pro- 10:05 nouncedenvelope, the subjectswere not able to regainidentification of sidedhesSout to 100-msdelay. Presentation of differentsound types re- FS. Modulation transfer function using temporal-probe tones. soltedin significantdifferences in performance.White noisepresented the Christopher Ahlstrom and Larry E. Humes (Division of Hearing and mostdifficult task, as shown by the low percentageof identificationof the Speech,Vanderbilt University, Nashville, TN 37212} leadingcar. The femalesinger and violinyielded the highestpercentages PsychoacousticMTFs weremeasured by embeddinga probetone in for leading-caridentification. SAM speechnoise. The speechnoise was 70 dB SPL overall,and the modulationdepth of lhis noisewas 60 dB. The modulationfrequencies were:0, 2.5, 5, 10,20, and35 Hz. The durationofeach tone pip was4.7 ms for frequencies500, 1414, and 4000 Hz. Bandwidths (3 riB} at each of the F3. Pitch and spectralestimation of speechbased on auditorysynchrony frequencieswere 19, 22, and 18Hz. Skirtslopes were between 6 and7 dB/ model. StephanieScheft {Department of Electrical Engineering& octave.Simple masking nearly predicted changes in theseMTFs in noise. ComputerScience, Rm. 36-521, MassachusettsInstitute of Technology, A SpeechTransmission Index {STI} derived from the MTFs in noisewas Cambridge,MA 02139} nobetter correlated {r = 0.95}with speech recognition scores than was the

$9 J. Acoust.Sec. Am. Suppl. 1, VoL 74, Fall 1983 106th Meeting:Acoustical Society of America S9 STI calculatedaccording to H. J. M. Stcenekcnand T. Houtgast,J. With monoticbursts the apparentsummation effect has a flat maximum Acoust.Soc. Am. 67, 318--326(1980}. [Work supportedby the Ve•ran's around a time interval between the burst onsets of about 60 ms. The Administration.] dichoticas well asthe monoticreflex arc containsat leastone nonlinearity since the summated effect of the bursts exceeds the arithinetic sum. The

10:20 measuredcharacteristics can be accountedfor quantitativelyby a model ßcontaining a peripherallinear adaptationstage with a recoverytime con- F6. Temporal effects of vowel productionon listeners' perceptionof s•nt on the order of 50 ms, a linear centraltemporal integrator with a speakerage. HeVoertJ. Oyer and Michael D. Trudeau(Speech and time constantof about200 ms and a threshold,all connectedin series.All HearingScience Section, The Ohio StateUniversity, 154 N. Oval Mall, thenumerical constants arc consistent with thosefound in neurophysinlo- Columbus,OH 43210} giealand psychophysicalexperiments. The inferencethat the threshold followsthe integratormay proveto be of major interest. Twenty-fourspeakers prolonged the vowels/a e i o u/and readthe passage"My Grandfather."The speakerswere divided into four groups of six(three males, three females} based on chronological age, 41-50 years, 11:05 51-60 years,61-70 years,and 71 yearsand over. Naive listenersprovided perecptualjudgements of eachspeaker's age based on the first two sen- F9. A demonstrationof peripheralconstraint on an auditory duration tencesfrom "My Grandfather."The speakers'vowel productions were diseriminationtask.GregoryJ. FlectandBrianR. Shelton(Department measuredto determinetime requiredto initiateand terminate each vowel. of Psychology,University of WesternOntario, London, Ontario, Canada These ten measuresplus time to articulate the four syllables N6A 5C2} /ma I gr•ndfaS•/and speakersex were regressed against speaker chrono- An earlierstudy investigated the discriminationof auditorydurations logicaland perceived ages. The bestsignifibant model for chronological presentedat a rapidrate in a two-alternativeforced-choice task. The re- ageyielded an R-Square of only0.428; while for thebest significant model sults indicated that a constant Weber fraction was obtained across base for perceivedage R-Square was 0.647. Results indicate that speakertem- durationsfrom 25-1600 ms ifs longinterstimulus interval (ISI) separated poralcontrol of speechexerts a stronginfluence on listenerp•rccption of the two alternativepresentations, but performancedegraded with short speakerage, but hasa relativelyweaker relationship with speaker'schron- basedurations ifa shortISI wasused [B. R. Shelton,J. Acoust.Soc. Am. ologicalage. These findings suggest that temporalaspects of speechare Suppl.1 72, S89(1982}]. Here, the samemeasurements were taken under criticalin estimationof speakerage. two presentationconditions: (1} a binauralpresentation of both intervals, and (2} a monauralpresentation of the two intervals,each to a different 10:35 ear. Basedurations of 25, 50, 100, and 200 ms were used,with ISI valuesof 25, 50, 100,200, 400, 800, and 1600ms. The binaurallypresented condi- F7. Octave equivalence in the processingof tonal sequences. tion replicatedthe previousresults, but the presentationof intervalsto Diana Deutsch(Center for Human InformationProcessing. University alternateears produced a markedimprovement in performance,especial- of California,San Diego, La Jolla,CA 92093) ly with shortISI presentations.This findingsuggests that the discrimina- An issueof considerabledebate concerns octave equivalence of tones tion of the durationof rapidly presentedauditory stimuli is restricted that arepresented in a sequentialsetting. In a previousstudy, Dentsch peripherally.[Work supported by NSERC.] [PerceptionPsychophys. 6, 411--412(1972}] showed that a well-known melodybecame unrecognizable when its component tones were displaced 11:20 randomlyto differentoctaves. It wasconcluded that, in accordancewith thetwo-channel model for theabstraction of pitchrelationships proposed F10. Auditory time constantsunified. Pierre Divenyi (Speechand by Deutsch[Psychol. Rev. 76, 300-307(1969}], octave equivalence effects HearingResearch, VA MedicalCenter, Martinez, CA 94553and INRS- do not operatedirectly in a sequentialsetting. It has,however, been ar- Telecommunications,University of Quebec,Verdun, Quebec,Canada guedthat distortion of melodiccontour was responsible for the recogni- H3E IH6} and RobertV. Shannon(Coleman Lab, 863 HSE, UCSF, San tionperformance obtained. To settlethis issue, a newparadigm was em- Francisco,CA 94143} ployed.Musically trained listeners were presented with novelsequences Psychophysicalmeasures of auditorytemporal integration typically of tones,which they recorded in musicalnotation. When the toneswithin yieldseveral different time constants depending on the task.An integra- a sequencewere in the sameoctave, a highperformance level was ob- tion timeconstant of 100to 300ms is proposedto explainthe relationship tained. However, when the toneswithin a sequencewere distributed betweenthreshold and burstduration JR. Piompand M. A. Bournart,3. acrossoctaves, performance deteriorated sharply. This resultconfirms Acoust.Soc. Am. 31, 749-758 {1959}].When click thresholdsare mea- thehypothesis that octave equivalence effects do notoperate directly in a suredin amplitude-modulatednoise the results are consistent with a much sequentialsetting. [Work supported by NIMH.] shorterintegration time of 10ms or lessIN. F. Viemeister,in Psychophy- sicsand Physiologyof Hearing,edited by Evansand Wilson(Academic, 10:S0 New York, 1977,pp. 419-427)]. The differencebetween these time con- FS. $tapediusreflex: On somefundamental temporal characteristics. stantsis thoughtto be due simplyto the differenttasks involved. The JozefJ. Zwisiocki(Institute for SensoryResearch, Syracuse University, longertime constantis calculatedassuming a linearintegrator operating on the input intensity.Any physiologicalintegration mechanism, how- Syracuse,NY 13210} ever,integrates neural activity, which is a compressirenonlinear function Effectsof neuraltemporal summation and adaptation on the stapedius of theinput intensity. An integratorwith a 10-mstime constant preeecded reflexare examinedwith the helpof monoticand dichotic pairs of tone by a compressirenonlinearity will produceapparent threshold integra- bursts.The toneintensities were sochosen that eachburst presentedsepa- tion timesof 100-300ms, depending on the magnitudeof the compres- ratelyevoked a constantresponse. The resultsshow that the apparent sion.Thus a singleintegration mechanismcan account for the apparently summationof theeffects of dichoticbursts is greaterthan that of monotic longtime constants for thresholdand the shorter timc constants for tem- burstsand decays monotonically as the interburst time interval increases. poraldiscrimination.

S10 J. Acoust.Soc. Am. Suppl. 1, Vol.74, Fall 1983, 106thMeeting: Acoustical Society of America S10 TUESDAY MORNING, 8 NOVEMBER 1983 FORUM ROOM, 8:30 TO 11:45 A.M.

SessionG. Physical AcousticsI: Novel Applications of Macrosonics

Robert E. Apfel, Chairman Departmentof MechanicalEngineering, Yale University, New Haven, Connecticut 06511

Chairman's Introductions8:30

Invited Papers