MONDAY MORNING, 14 MAY 2012 HALL B, 8:20 AM TO 9:20 AM Keynote Lecture MONDAY ...

309 Pages·2012·2.16 MB·English

MONDAYMORNING,14MAY2012 HALLB,8:20A.M.TO9:20A.M.
M
KeynoteLecture
A
N.
O
M
a
8:20 1
Languagelearningandthedevelopingbrain:Cross-culturalstudiesunraveltheeffectsofbiologyandculture.PatriciaK.Kuhl
(Co-Director,InstituteforLearningandBrainSciences,Co-Director,NSFScienceofLearningCenter(LIFE),UniversityofWashing-
ton,Seattle,Washington98195)
Cross-culturalstudiesshowthatinfantsarebornwithinnateabilitiesthatmakethem“citizensoftheworld.”Bytheendofthefirst
yearoflife,however,cultureproducesadramatictransition.Infants’abilitiestodiscerndifferencesinnative-languagesoundsincrease,
andtheirabilitiestodiscriminatesoundsfromotherlanguagesdecreases.Thisperceptualnarrowingofinfants’languageskillsiscaused
by two interacting factors: the child’s computational skills and their social brains. Computational skills allow rapid and automatic
“statisticallearning”andsocialinteractionisnecessaryforthiscomputationallearningprocesstooccur.Thiscombinationproducesthe
neuroplasticityofthechild’smind,andcontrastswiththemoreexpert(butlessopen)mindoftheadult.Neuroimagingofinfantsusing
Magnetoencephalography(MEG)ishelpingexplaintheextraordinarylearningofyoungchildren.Theworkisleadingtoanewtheoreti-
calaccountforthe“criticalperiod”forlanguage.Understandingtheinteractionbetweenbiologyandcultureinhumanlearninginthe
domainoflanguagemayunlocksomeofthemysteriesandmechanismsofthehumanmind.
MONDAYMORNING,14MAY2012 HALLA,9:15A.M.TO12:40P.M.
Session1aAA
ArchitecturalAcousticsandSignalProcessinginAcoustics:Multiple-MicrophoneMeasurements
andAnalysisinRoomAcousticsI
BoazRafaely,Cochair
[email protected]
SamClapp,Cochair
[email protected]
Chair’sIntroduction—9:15
InvitedPapers
9:20
1aAA1.Sphericalmicrophonearrayprocessingofroomimpulseresponsedatausingfrequencysmoothingandsingular-value
decomposition.NejemHuleihelandBoazRafaely(BGU,BeerSeva,84105,[email protected])
Roomimpulseresponses(RIRs)playanimportantroleinacousticalsignalprocessingandroomacousticsanalysis.Theproblemof
estimatingthedirections-of-arrival(DOA)ofasourceinaroomanditsreflectionsusingRIRdataandmicrophonearrays,isconsidered.
Optimalarrayprocessingmethodsproposedforsoundfieldanalysisusingsphericalmicrophonearrayareutilized.Becauseofthepossi-
blecoherencebetweenthesignals,thesemethodscannotbeuseddirectly,andapreprocessingtechniqueistypicallyneeded.Recently,
frequencysmoothing(FS)asapreprocessingtechniquehasbeendevelopedforsphericalmicrophonearrays.AlthoughFShasalready
beendevelopedforthegeneralcase,thestudyofitsperformanceinacomprehensivemanner,forsphericalmicrophonearrayswithRIR
datahasnotbeenpreviouslypresented.Therefore,theoreticalanalysisofthesignalmatrixstructureusingRIRdataisperformed.The
conclusionsfromthisanalysismayleadtoanoptimizationofthesmoothingprocess.Amethodforanoptimalselectionoffrequencies
inthesmoothingprocessforthecaseofonereflectionispresented,followedbyformulationsforsmoothinginthemoregeneralcase.
Finally,FSanditsrelationtoSVDofthearraydatamatrixarealsopresentedanddiscussed.
9:40
1aAA2.Jointsphericalbeamformingfordirectionalanalysisofreflectionsinrooms.HaiMorgenstern(Ben-GurionUniversityof
theNegev,Beer-Sheva,[email protected]),FranzZotter(UniversityofMusicandPerformingArts,Graz),andBoazRafaely
(Ben-GurionUniversityoftheNegev,Beer-Sheva)
Thiscontributionpresentsanewapproachforanalyzingspatialdirectionsinroomimpulseresponsescapturedwithsourceandre-
ceiverofadjustabledirectivity.Adistinctpeakinaroomimpulseresponseisusuallyassociatedwithanacousticpathlengthofdirector
reflectedsound.Giventheabilitytomodifythedirectivityofsourceandreceiverbysphericalbeamforming,beamcoefficientscanbe
3207 J.Acoust.Soc.Am.,Vol.131,No.4,Pt.2,April2012 Acoustics2012HongKong 3207
adjustedastoemphasizethepeakatapreselectedtimeinstant.Wepresentanewapproachtojointlyoptimizethecoefficientsforboth
source and receiver under the constraint of a unit peak amplitude while minimizing the energy of the response. The beam pattern
describedbythesecoefficientshighlightsthedominantacousticpathdirectionsofthecorrespondingpathlengthatthesourceandthe
receiver.
10:00
1aAA3.Exploringsphericalmicrophonearraysforroomacousticanalysis.JensMeyerandGaryW.Elko(mhacoustics,25ASum-
mitAve,SummitNJ07901,[email protected])
Sphericalmicrophonearraysofferseveraladvantagesoverlinearmicrophonearraysandsinglesensormicrophonesforroomacous-
ticanalysis.Someadvantagesaretheabilityto:a)steerthedirectionalresponsein3Dspace,b)changethebeampatternshape(inde-
pendentofthelookdirection)andc)spatialdecompositionofthesoundfieldintosphericalharmonicorthonormalcomponents.Allof
thesefeaturesareavailableonlineandofflinemeaningthattheanalysiscanbeperformedafterthemeasurementhasbeendone.Wewill
presentstandardmeasurementssuchasspatiallydependentreverberationtime,diffuseness,etc.thattakeadvantageofthesphericalarray
decompositionofthesoundfield.Wewillalsorevisitthespatialcorrelationfunction,ameasureverysuitableforsphercialarraybased
roomanalysis.Resultsforvarioussetupswillbepresented.
10:20
1aAA4.OntheInfluenceofsamplingerrorsontheperceptionofspatialsoundfieldsusingsphericalmicrophonearraysforaur-
alization.JohannesNowak(TUIlmenau,Helmholtzplatz2,98693Ilmenau,Germany,[email protected])
Sphericalmicrophonedistributionsallowathreedimensionalsamplingofthesoundfieldinaroom.Thesemicrophonearraydata
canbeusedforauralizationonvariousplaybacksystems.Theaimofauralizationisthereproductionofthesampledspatialsoundfield
inordertogivethelistenertheimpressionofbeinginthemeasuredroom.Duetothediscretespatialsamplingprocessspatialaliasing
corruptsthemeasureddata.Thereforetheresultingauralizationqualityisaffectedintermsofitsspatialcharacteristics.Subjectivequal-
itymeasuresforthespaciousnessofsoundfieldscanberepresentedbysourcelocalizationaccuracy,theapparentsourcewidth(ASW)
andthelistenerenvelopment(LEV).Thesesubjectivefeaturesarestronglyrelatedtoobjectivemeasureslikeinteraurallevelandtime
differences(ILDandITD)ortheinterauralcrosscorrelation(IACC).Insubjectivelisteningteststheinfluenceofsamplingerrorsonthe
binauralreproductionofasampledsoundfieldisinvestigated.TheresultsarecorrelatedwithITD,ILDandwithIACCinordertogain
anobjectivequalitymeasureforsoundfieldsrecordedwtihsphericalmicrophonearrays.Theinvestigationsarebasedonrealmeasure-
mentdatatakingvariousdirectionsofarrivalanddifferentroomsintoaccount.
10:40–11:00Break
11:00
1aAA5.Interfacingsphericalharmonicsandroomsimulationalgorithms.MichaelVorlaender,MartinPollow,andSoenkePelzer
(RWTHAachenUniversity,D-52056Aachen,Germany,[email protected])
Room acoustic simulation by using geometrical acousticsis usually implemented withbinaural receivers. Wave models such as
FEMareeasilyapplicablewithbinauralinterfacesaswell.Thisway,however,thesignalsarerestrictedtoaspecificsetofHRTF,anda
tedioustaskistoadapttheresultstoaproperreproductionsystemwithverylimitedpossibilitiesoflistenerindividualization.Witha
moregeneralinterfacesuchassphericalharmonics,roomacousticspatialdatacouldbecreatedinintermediatesolutions.Inpost-proc-
essingthiscanleadtovariousbinauralrepresentationsortoreproductionwithAmbisonics(Dalenba¨ck,ICA1995).Inthispaperitisdis-
cussed how standard routines in geometrical acoustics must be changed in order to implement multi-channel spherical microphone
arrays.Furthermore,thecorrespondingoutputdatacanbemulti-channeltimesignalsortemporalSHcoefficientsoranyothersuitable
spectralformat.TheamountofdataandsignalprocessingaffectsCPUtimeandmemory.Thediscussionthereforeisfocusedonfeasi-
bilityandonconsequencesonthereal-timeperformanceontheonehand,andonthespatialqualityoftheroomresponse,ontheother.
11:20
1aAA6.Theuseofmulti-channelmicrophoneandloudspeakerarraystoevaluateroomacoustics.SamuelClapp(GraduatePro-
gram in Architectural Acoustics, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180, [email protected]), Anne Guthrie
(Arup,77WaterStreet,NewYork,NY10005),JonasBraasch,andNingXiang(GraduatePrograminArchitecturalAcoustics,Rensse-
laerPolytechnicInstitute,1108thStreet,Troy,NY12180)
Mostroomacousticparametersarecalculatedwithdatafromomni-directionalorfigure-of-eightmicrophones.Usingaspherical
microphone array to record room impulse responses can yield more information about the spatial characteristics of the sound field,
includingspatialuniformityandthedirectionsofindividualreflections.Inthisresearch,asphericalarraywasusedtomeasureroom
impulseresponsesonstageandintheaudienceinawidevarietyofconcerthallsthroughoutNewYorkState,withboththemicrophone
arrayandanartificialhead.Theresultswereanalyzedusingbeamformingtechniquestodeterminespatialinformationaboutthesound
fieldandcomparedtotheresultsofgeometricalacousticsandbinaurallocalizationmodels.Ofparticularinterestwashowthespatial
datacanhelptodifferentiatebetweendifferentspacesorlistenerpositionsthatexhibitsimilarvaluesforconventionalmetrics.Auraliza-
tionswerecreatedusingbothheadphoneplaybackandsecond-orderambisonicplaybackviaaloudspeakerarray.Thesesystemswere
evaluatedobjectivelytocomparethereproductionsystemswiththemeasureddata.Listenerswererecruitedforlisteningtestsusing
eachreproductionmethod.Theywereaskedtoevaluatethehallsonbothobjectivemeasuresandsubjectivepreference,andtheresults
ofbinauralandambisonicplaybackwerecompared.
3208 J.Acoust.Soc.Am.,Vol.131,No.4,Pt.2,April2012 Acoustics2012HongKong 3208
11:40
1aAA7.Analysisandsynthesisofroomtransferfunctionoveraregionofspaceusingdistributedsphericalmicrophonearrays.
M
Thushara Abhayapala (Australian National University, Canberra, ACT 0200 Australia, [email protected]), and Pra-
A
sangaSamarasinghe(AustralianNationalUniversity)
N.
Spatialsoundfieldrecordingandreproductioninreverberantroomsrequiresmeasurementofroomtransferfunctions(RTF)andcor- O
respondingcompensationsuchasroomequalizationtoavoidunintendedeffects.Typically,RTFrapidlyvariesovertheroomandhence M
requiresalargenumberofpointtopointmeasurementstocharacterizetheroom.Thispaperuses(i)anefficientparameterizationofthe a
1
acoustictransferfunctionoveraregionofspace,firstintroducedbyBetlehemetal[“Theoryanddesignofsoundfieldreproductionin
reverberantrooms,”JournaloftheAcousticSocietyofAmerica,Vol.117,Issue4,2005]and(ii)amethodtomergespatialsoundfield
recordedbydistributedhigherordermicrophones(suchassphericalarrays)toanalyzeandsynthesizetheroomtransferfunctionovera
regionofspace.Thismethodprovidesapracticalwaytomeasureroomtransferfunctionoverlargeareaswithaminimumnumberof
measurements.
12:00
1aAA8. On the importance of room acoustics in multi-microphone speech enhancement. Sharon Gannot (Bar-Ilan University,
[email protected])
Speech quality might significantly deteriorate in presence of interference. Multi-microphone measurements can be utilized to
enhancespeechqualityandintelligibilityonlyifroomacousticsistakenintoconsideration.Thevitalroleoftheacoustictransferfunc-
tion (ATF) between the sources and the microphones is demonstrated in two important cases: the minimum variance distortionless
response(MVDR)andthelinearlyconstrainedminimumvariance(LCMV)beamformers.TheLCMVdealswiththemoregeneralcase
ofmultipledesiredspeakers.ItisarguedthattheMVDRbeamformerexhibitsatradeoffbetweentheamountofspeechdereverberation
and noise reduction. The level of noise reduction, sacrificed when complete dereverberation is required, is shown to depend on the
direct-to-reverberationratio.Whenthereverberationlevelistolerable,practicalbeamformerscanbedesignedbysubstitutingtheATFs
withtheircorrespondingrelativetransferfunctions(RTFs).Asnodereverberationisperformedbythesebeamformers,ahigherlevelof
noisereductioncanbeachieved.IncomparisonwiththeATFs,theRTFsexhibitshorterimpulseresponses.Moreover,sincenon-blind
procedurescanbeadopted,accurateRTFestimatesmightbeobtained.ThreesuchRTFestimationmethodsarediscussed.Finally,a
comprehensiveexperimentalstudyinrealacousticalenvironmentsdemonstratesthebenefitsofusingtheproposedbeamformers.
12:20
1aAA9.Representationofthespatialimpulseresponseofaroom.FilippoM.Fazi(UniversityofSouthampton,UniversityRoad,
SO171BJ,Southampton,UK,[email protected]),MarkusNoisternig,andOlivierWarusfel(IRCAM-UMRCNRS,1placeIgor-
Stravinsky,75004Paris,France)
Microphonearraysallowforthemeasurementoftheso-calledspatialimpulseresponse(SIR)ofaroomorofaconcerthall.TheSIR
providesalocaldescriptionofthereverberantfieldofthatenvironmentasafunctionofbothtimeandspace.Itisshownthat,under
givenassumptions,theSIRcanbedescribedbymeansofanintegraloperator,theso-calledHerglotzwavefunction,whichrepresents
aninfinitesuperpositionofplanewavesarrivingfromallpossibledirections.Thekernelofthisoperator(theHerglotzkernel)contains
alltheinformationontheSIR.InpracticalcasesonlyalimitedamountofinformationisavailabletocomputetheHerglotzkernel,typi-
callybecauseafinitenumberofsensorsisusedforthemeasurement.Inthatrespect,severalalternativesarediscussedtorepresentthe
Herglotzdensityasasumofafinitenumberofbasisfunctions.Someresultsfornumericalsimulationsarethenpresented,whichshow
theHerglotzkernelforsimpleexamples.Finally,somelimitationsofthisrepresentationarediscussed,especiallythoseimposedbythe
useofrealmicrophonearrays.
3209 J.Acoust.Soc.Am.,Vol.131,No.4,Pt.2,April2012 Acoustics2012HongKong 3209
MONDAYMORNING,14MAY2012 S223,9:20A.M.TO12:40P.M.
Session1aBA
BiomedicalAcoustics:TherapeuticUltrasound
YunJing,Cochair
[email protected]
HairongZheng,Cochair
[email protected]
ContributedPapers
9:20 10:00
1aBA1. Acousto-optic monitoringof high-intensity focused ultrasound 1aBA3.Real-timephasecorrectionfortranscranialfocusedultrasound
lesion formation with fibre-coupled autocorrelation detection. Samuel surgery.YunJing(NorthCarolinaStateUniversity,911OvalDr.,EBIII,
PowellandTerenceS.Leung(DepartmentofMedicalPhysicsandBioen- CampusBox7910,Raleigh,27695NC,[email protected])
gineering, Malet Place Engineering Building, University College London,
Theskullhasbeenabarriertotranscranialfocusedultrasoundtherapy,
London,WC1E6BT,UK.,[email protected])
becauseofitsstrongphaseaberration.Previousmethodsforphasecorrec-
Afocusedacousticsourceinsonifiesanopticallyturbidmedium.Under tionarebasedonnumericallysolvingthewaveequation,whichoutputsthe
coherent illumination the optical field in the focal region of the acoustic desired phasedelay for each transducer element.These methodsare typi-
sourceisphasemodulatedbytheacousto-opticinteraction.Thedegreeof callyquitetime-consuming.Thepresentmethodaimstoachievereal-time
thismodulationcanbedeterminedusingafibre-coupledopticalautocorrela- phasecorrection.ThismethodisbasedontheEikonalequation,whichisa
tion technique. Exploiting both the contrast of biological tissues at near- highfrequencyapproximationtothewaveequation.Itfullyaccountsforthe
infraredwavelengths,andthenon-linearityofthephasemodulationprocess, refractionintheskull,whichisthemaincontributiontothephaseaberration
itmaybepossibletodeterminethepertinentopticalpropertiesofbiological in the skull. Fast marching method (FMM) is used to solve the Eikonal
tissueswithaspatialresolutioncomparabletothedimensionsoftheacous- equation.Preliminaryresultsshowthat,solvingtheEikonalequationisover
tic focus. The same acoustic source may be employed therapeutically at 100 times faster than solving the wave equation by the finite-difference
higher power levels to instigate thermal necrosis and associated optical time-domain method. More importantly, a relatively sharp and accurate
changesine.g.,tumoursoftheprostate.Whilsttheproposeddetectionre- focuscanbeachievedinthebrainusingthepresentmethod.
gime has significant technical and practical advantages over alternative
approachescurrentlyunderinvestigation,itisincompatiblewithsuchtreat-
10:20
mentpowerlevels.Wepresentthetheoryofaninterleavedtreatmentand
sensingtechniquewhichcouldallowtheuseofourinherentlycompactand 1aBA4.Theeffectsofacousticpowerandexposuretimeonthehypere-
robust detection mechanism during HIFU therapy, simulated results choinultrasoundimagesat55(cid:2)CusingMRIandUSguidedHIFUina
obtained using a novel highly-parallel Monte-Carlo simulation code, and bovineliverspecimen.FaqiLi,HuarongYi,MingsongZhong,HuijianAi,
initial experimental results from the formation of lesions within ex vivo JieChen,andZhibiaoWang(SateKeyLaboratoryofMedicalUltrasound
chickenbreastsamples. EngineeringCo-foundedbyChongqingandMinistryofScienceandTech-
nology,DepartmenteofBiomedicalEngeering,ChongqingMedicalUniver-
sity,Chongqing400016,P.R.China,[email protected])
ExvivobovineliverspecimenswereexposedtotheMRI-guidedHIFU
with the focusing depth of 15 mm in the specimens and various acoustic
9:40
power(50W,100W,150W,200W,250Wand300W).Ourinterestwas
1aBA2.Cavitationbubbleinalcoholaqueoussolutions.WeizhongChen, focusedonacaseof55(cid:2)Cinsitutemperature.Thetemperatureinsituwas
WeichengCui,andSuibaoQi(KeyLaboratoryofModernAcoustics,Min- monitoredviatheT-mapofMRI.Theexposuretimeneededtoreach55(cid:2)C
istryofEducation,andInstituteofAcoustics,NanjingUniversity,Nanjing, in the focus for a acoustic power was recorded.The same procedure was
210093,China,[email protected]) repeated to new but similar bovine liver exposed to the US-guidedHIFU
withthesamesonicationparameters.Theprocedurewasalsomonitoredby
Thealcohol,asasurfaceactiveagent,playsanimportantroleinsonolu-
apassivecavitationdetectionsystem.Theresultsshowedtoreach55(cid:2)Cin
minescence.Theviolentpulsationofthecavitationbubblemakesthesono-
situtheexposuretimedecreasedwiththeincreaseofacousticpower.The
luminescence possible. In this talking we report the experimental
coagulativenecrosisoccurredwhentheacousticpowerwas50W,butno
measurementforthebubblepulsationsinalcoholaqueoussolutionsatdif-
hyperechoinUSimagesandhalfharmonicemissionwerefound.Thecoag-
ferentconcentrationsubjectedtotheexcitationoftheultrasound.Theresults
ulativenecrosis,hyperechoicUSimagesandhalfharmonicemissionswere
showsthatthemaximumradiusandthebearableintensityoftheultrasound
observedwhentheacousticpowerwas100Worgreater.At55(cid:2)C,sinceno
ofthebubbledecreasewiththeconcentrationincreasing.Atthesametime,
boilingbubblesoccurred,thereforeweconcludedthatthehyperechoinUS
thecompressionratioofthevolumegoesalsointodeclineastheconcentra-
imageswerecausedbyacousticcavitationwhoseoccurrenceisdetermined
tionincreases.Theseresultsareconsistentwiththeobservationsofsonolu-
by the applied acoustic power. Keywords: MRI-guided HIFU, US-guided
minescence in alcohol aqueous solutions. And we conclude that the
HIFU,Coagulativenecrosis,hyperecho,AcousticcavitationThisworkwas
weakenedbubblepulsationcausesmainlythesonoluminescence darkened
supported by National Nature and Science Foundation of China (No.
in alcoholaqueoussolutions.A questionaboutdecreasinginthebearable
30830040,30970827)
ultrasoundintensityofthecavitationbubbleinalcoholaqueoussolutionis
stillopenandworthyoffurtherinvestigation. 10:40–11:00Break
3210 J.Acoust.Soc.Am.,Vol.131,No.4,Pt.2,April2012 Acoustics2012HongKong 3210
11:00 livertissueexposedto1.12MHzHIFUpulses,whilethefocustemperature
wasrecorded.Theinertialcavitationdose(ICD)wascalculatedtoanalyze
1aBA5.Generatinguniformlesionsinhighintensityfocusedultrasound
thecavitationactivityqualitatively.Thecorrelationsofcavitationactivity, M
ablation. Yufeng Zhou (Nanyang Technological University, 50 Nanyang
temperatureandfocuspressurewerediscussed.[Thisworkissupportedby A
Ave.,Singapore,639798,[email protected])
theNationalBasicResearchProgram973(GrantNo.2011CB707900)from N.
High intensity focused ultrasound (HIFU) is emerging as an effective MinistryofScienceandTechnology,China,NationalNaturalScienceFoun- O
oncology treatment modality. Because of thermal diffusion from nearby dationofChina(11174141),andtheFundamentalResearchFundsforthe M
spots, the lesion size will gradually become larger as HIFU progresses. Central Universities (Grant Nos. 1103020402, 1116020410 and a
1
However,uniformlesionswiththeleastenergyexposurearepreferredby 1112020401)]
thephysicianintumorablation.Inthisstudy,analgorithmwasdeveloped
todeterminethenumberofpulsesdeliveredtoeachspotinordertogenerate 12:00
uniformlesionpatternthatfillstheregion-of-interestcompletelyusingdif-
1aBA8. Infrared and hydrophone system for eastimating the output
ferentscanningpathways(rasterscanning,spiralscanningfromthecenter
powerofhighintensityfocusedultrasoundtransducer.YingYu,Guo-
totheoutsideandfromtheoutsidetothecenter),spotspacing,andmotion
fengShen,JingfengBai,andYazhuChen(BiomedicalInstrumentInstitute,
time.Itisfoundthatspiralscanningfromtheoutsidetothecenterwithspot
SchoolofBiomedicalEngineering,ShanghaiJiaoTongUniversity,Shang-
spacingof2mmandmotiontimelessthan10swouldneedtheleastnum-
hai200030,China,[email protected])
berofpulsesinuniformlesionproductionwiththeminimaltemperatureele-
vation.Inaddition,theeffectsofthermalpropertiesoftissue(i.e.,specific Outputpowerofhighintensityfocusedultrasound(HIFU)transduceris
heatcapacity,convectiveheattransfercoefficient,andthermalconductivity) not only important for the safety and efficiency of clinical treatment, but
on HIFU ablation were investigated. Altogether, dynamically adjusting also for therapy planning in medical applications. In the current paper, a
ultrasound exposure energy can improve the efficacy and safety of HIFU methodwasproposedtoestimateoutputpowerofHIFUusingahydrophone
ablation,andthetreatmentplanningdependsonthescanningprotocoland and infrared system. The proposed method is independent of the thermal
thermalpropertiesofthetarget. andacousticparametersoftheacousticabsorberandthetypeoftransducer
thathasbeenmeasured.Thismethodconsistedoffivesteps.Theamplitude
11:20
absorption coefficient of the medium was measured through the first two
1aBA6.Efficientgenerationofcavitationbubblesbydual-frequencyex- steps.Throughthesecondandthirdsteps,weestimatedtheratiooftheheat
posure.JunYasuda(TohokuUniversity,6-6-05AramakijiAobaAoba-ku capacityperunitvolumetotheultrasonicamplitudeabsorptioncoefficient
Sendai-shi 980-8579, Japan, [email protected]), Ryo Takagi, of the absorber.In fourthstep, thetemperature changeat the absorber/air
Shin Yoshizawa, and Shin-ichiro Umemura (Tohoku University, 6-6-05 wascapturedbyanIRcamera,andthetemperaturechangerate(TCR)was
AramakijiAobaAoba-kuSendai-shi980-8579,Japan) usedtoestimatetheintensitybasedontheparametersmeasuredbythefirst
threesteps.Inlaststep,thesoundpowerofHIFUtransducerathighdriving
Microbubbles are knowntoenhance highintensityfocusedultrasound
voltagecanbeobtainedfollowingtherelationshipbetweenthesoundinten-
(HIFU)treatment,whichisanewcancertreatmentmethod.Highlynegative
sityandsoundpower.Themethodwasproposedandsimulatedinthree2-D
acousticpressurecanefficientlygeneratecavitationmicrobubbles,butitis
1.36MHz-phasedarraysandtwokindsofabsorbers.Inlaststep,thesound
difficulttoobtainatthefocusofHIFUbecauseofnonlinearpropagation.In
powerofHIFUtransducerathighdrivingvoltagecanbeobtainedfollowing
ourpreviousstudy,a “Dual-FrequencyExcitation”methodwassuggested
therelationshipbetweenthesoundintensityandsoundpower.
to synthesize waveforms emphasizing either the positive-peak-pressure or
thenegative-peak-pressurebysuperimposingthesecondharmonicontothe
12:20
fundamental.Inthisstudy,fourdifferenttypeofdual-frequencyexposure
sequence at the fundamental frequency of 0.8 MHz were used, and the 1aBA9.AnAcousticbackscatter-basedmethodforestimatingattenua-
behaviorofcavitationbubblescapturedbyahigh-speedcamerawascom- tion towards monitoring lesion formation in high intensity focused
pared.Inthefirstandsecondsequences,thepositive-peak-pressureempha- ultrasound. Siavash Rahimian and Jahan Tavakkoli (Department of
sized(P)andnegative-peak-pressureemphasized(N)waveswereemployed Physics, Ryerson University, Toronto, ON, Canada, M5B 2K3, siavash.
for 125 ls, respectively. In the third sequence, the N and P waves were [email protected])
employed in the earlier and later 62.5 ls, respectively, and they were
exchanged in the forth sequence. In the results, the amount of cavitation Thisworkinvestigatedthetransientcharacteristicsoftissueattenuation
bubbles generated by the third sequence was significantly more than the coefficientbefore,duringandafterHIFUtreatmentatdifferenttotalacous-
otherthreesequences.Thecavitatinbubbles,generatedbytheNwaves,are tic powers (TAP) in ex-vivo porcine muscle tissues. Dynamic changes of
thoughttohaveprovidedapressure-releasesurfaceconvertingthePtoN attenuation coefficient parameters were correlated with conventional B-
waves,whichfurthergeneratedcavitationbubbles. mode ultrasound images over the whole HIFU treatment process. Two-
dimensionalpulse-echoradiofrequency(RF)datawereacquiredtoestimate
11:40 thechangesofleastsquaresattenuationcoefficientslope(~b)andattenua-
tion coefficient intercept (~a0) averaged in the region of interest, and to
1aBA7.Detectionofhighintensityfocusedultrasoundinducedcavita-
construct ~b, ~a0, and B-mode images simultaneously. During HIFU
tionactivityinlivertissue.TingboFan,ZhenboLiu,XiashengGuo,and
treatment, bubble activities were visible as strong hyperechoic regions in
Dong Zhang (Key Laboratory of Modern Acoustics (MOE), Institute of
theB-modeimages,causingfluctuationsin~band~a0duringtreatment.
Acoustics,NanjingUniversity,[email protected])
~b and ~a0 increased with the appearance of bubble clouds in the B-
Microbubbles are known to be able to enhance the thermal effect of modeimagestovaluesintherangeof1.5-2.5[dB/(MHz.cm)]and4-5[dB/
ultrasound. In HIFU procedure, microbubbles can be generated when the cm], respectively. After thetreatment,~b and~a0 graduallydecreased,
peaknegativepressureislargeenoughorthetemperatureexceedstheboil- accompaniedby fadeout of hyperechoic spotin theB-modeimages,until
ing point. In this work, cavitationactivities in various exposure protocols theywerestableat0.75-1[dB/(MHz.cm)]and1-1.5[dB/cm],respectively.
with equal total acoustic energy but variable focus pressure and variable After treatment, ~b and ~a0 images outperformed B-mode images by
dutycycleweremonitoredinvitro.A10MHzfocusedpassivecavitation havingsignificantlyhighercontrasttospeckleratiosatallinvestigatedTAP
detectortransducerwasusedtocaptureacousticemissionsemanatedfrom values.
3211 J.Acoust.Soc.Am.,Vol.131,No.4,Pt.2,April2012 Acoustics2012HongKong 3211
MONDAYMORNING,14MAY2012 S221,9:20A.M.TO12:00NOON
Session1aEA
EngineeringAcousticsandNoise:MufflersandSilencers
Y.S.Choi,Cochair
[email protected]
Y.Y.Lee,Cochair
[email protected]
ContributedPapers
9:20 10:00
1aEA1.Systematicdesignofreversalflowmufflersbytopologyoptimi- 1aEA3.Narrowsidebranchesforductsilencing.S.K.Tang(Department
zation.JinWooLee(DivisionofMechanicalEngineering,AjouUniversity, ofBuildingServicesEngineering,TheHongKongPolytechnicUniversity,
San 5 Woncheon-Dong, Yeongtong-Gu, Suwon 443-749, Republic of HungHum,HongKong,China,[email protected])
Korea,[email protected])
Anarrowsidebranchattachedtotherigidwallofaductwillresultin
Anewmufflerdesignmethodissuggestedforsystematicdesignofrever- highsoundtransmissionlossacrossitatitsresonancefrequencies.Coupling
salflowmufflers.Inthenewmethod,amufflerdesignproblemisreformu- narrowsidebranchestogetherwillthereforeproduceabroadbandsilencing
latedasanacousticaltopologyoptimizationproblem,wherethetransmission deviceforductnoisecontrol.However,thesidebranchlengthvariationwill
loss at the frequency of interest is maximized. A finite element model is affectthebroadbandperformance.Numericalinvestigationwascarriedout
employedforacousticalanalysis,andonedesignvariableisassignedtoeach inthisstudytounderstandtheeffectsofthesidebranchlengthvariationand
finiteelementandchangescontinuouslyfromzerotoone.Whenthedesign the sidebranch width on the overall sound attenuation spectrum of the
variablebecomesone,theassociatedfiniteelementisfilledwithrigidbody coupled sidebranches. It is found that broadbandsound attenuation below
andanincidentacousticwave isfullyreflected.Therigidbodiesbuildup thefirsthighermodecut-offfrequencyofthemainductofover20dBacross
partitions, which improve the acoustical characteristics of flow-reversing theworkingbandwidthcanbeachievedifthelengthvariationandwidthsof
chambers. When the design variable becomes zero, an incident acoustic thesidebranchesareappropriatelychosen.
waveisfreelytransmittedtotheotherside.Sincetheoptimallocationand
lengthofthepartitionsaredeterminedautomaticallybythesuggestedmuf-
flerdesignmethod, the internal configurationofthereversalflowmufflers 10:20
doesnotdependonthedesigners’intuitionandexperiences.Severalnumeri-
1aEA4. Effect of geometric uncertainties and variations on the one-
calresultsprovethefeasibilityofthesuggestedmufflerdesignmethod.
dimensionalsoundtransmissioninaductwithperiodicresonatorarray.
9:40 Jeong-GuonIhandEun-OkYim(KAIST,[email protected])
1aEA2. Transversal modes and acoustic attenuation characteristics of Sound transmission in a one-dimensional duct with periodic resonator
rectangular and oval silencers with perforated tube. Zhi Fang and arrayischaracterizedbyBraggstopbandduetoperiodicityandresonance
ZhenlinJi(SchoolofPowerandEnergyEngineering,HarbinEngineering stopband due to resonator. Involved geometric parameters affecting the
University,Harbin,Heilongjiang,P.R.China,[email protected]) acoustic characteristics are resonator spacing, resonator length, widths or
areasofmainductandresonator.Distortionsofsuchgeometricparameters
As the analytical method is not suitable for the silencers with arbitrary areduetouncertaintiesinmanufacturingandduetointentionaldesignvar-
cross-sectionalshape,thefiniteelementmethodisdevelopedtocalculatethe iations forfocusingona target frequency range. Aside-brancharraywas
transversal modes of rectangular and oval silencers with circular perforated takenasthetestexample.Stopbandinformationwasobtainedbyfour-pole
tube,thecorrespondingfiniteelementformulationisderivedandthecomputa- matrixandBlochwavetheory.Areaandlengthratiosbetweenside-branch
tionalcodeiswritten.Inordertovalidatethepresentfiniteelementformulation and main duct periodicity properties were varied from zero to unity.
andcomputationalcode,thetransversalmodalfrequenciesofcircularconcen- Randomized distortions were generated from either Gaussian or uniform
tric straight-through perforated tube silencer are evaluated analytically and random distribution. As a deterministic distortion, sine function was
comparedwiththefiniteelementresults,andgoodagreementsbetweenthem employed. Simulation results showed that bandwidths and frequencies of
areobserved.Then,thefiniteelementmethodisusedtoinvestigatetheeffects stopbandswerehighlyaffectedbythelengthratio.Alongwiththeincrease
ofholediameter,porosityandtubeoffsetonthetransversalmodesandacoustic of random distortion rate or function period of deterministic distortions,
attenuationcharacteristicsofrectangularandovalsilencerswithcircularperfo- sound transmission at stopbands decreases, while passband transmission
rated tube. The numerical results demonstrate that, smaller hole diameter or increases.Itwasalsoshownthatonecanchangethebandwidthand/orfre-
higherporosityleadstohigherplanewavecut-offfrequenciesandbetteracous- quency of stopbands as desired for sound reduction. (Work partially sup-
ticattenuationinthemiddlefrequencyrange,andtheholediameterandporos- portedbyBK21projectandNCRC(NRF2011-0018242))
ity have negligible effect on the plane wave cut-off frequencies when the
porosityishigherthan40%.Theplanewavecut-offfrequenciesofthenon-
coaxialsilencersarelowerthantheconcentricconfigurationsingeneral. 10:40–11:00Break
3212 J.Acoust.Soc.Am.,Vol.131,No.4,Pt.2,April2012 Acoustics2012HongKong 3212
11:00 to-middlefrequencies,whichactivenoisecontrolhasthepotentialtocontrol
thelow-frequencynoise,issuerelatedtoreliabilityandcostremains.Con-
1aEA5.Newsemi-activemufflersystembasedontheH-Qtubeconcept.
cerning the real practical situation, passive control is the most preferable M
Xueguang Liu, Changchun Yin, Ye Wang, Shiming Cui, and Chunxia Li
choice.Thetraditionalin-ductsilencersareinsplittertype,withabulkoffi- A
(SchoolofEnergyandPowerEngineering;HarbinEngineeringUniversity,
Harbin,Heilongjiang,[email protected]) brous material as duct lining. The existing passive silencers are usually N.
bulky and long and can give a desirable performance at mid-to-high fre- O
For a fixed bandwidth noise, the appropriate control device is used to quencies.Mostideallythesilencerinconcernedshouldbeabletohandlea M
change the internal structure of the semi-active muffler to get the large broadfrequencybandandcompactinsize.Inthispaper,theperformanceof a
1
amountofnoisereduction.ThispaperanalyzestheprincipleofHershcel- a new silencer design was examined and optimized using computation
Quincketube,thenaccordingtotheprincipleoftheHershcel-Quincketube, approachwithexperimentalverification.
asemi-activesilencingdeviceispresentedhere,whichcaneffectivelycon-
11:40
trolthenoise.Thenatestbenchbasingonthedesignisbuilt.Thecontrol
systemwhichincludesthecontrolofthevalvesandthesteppingmotoris 1aEA7. Determination of sound reflection coefficient of circular duct
studiedhere.Intheconditionswithoutflow,theacousticcharacteristictest- usingtime-domaincomputationalfluiddynamicsmethod.ChenLiuand
inghasbeendoneusingthecontrolsystems.Itshowsthatthevalvesandthe ZhenlinJi(CollegeofPowerandEnergyEngineering,HarbinEngineering
stepping motor have a rapid response, meanwhile, the testing results are University, Harbin, Heilongjiang 150001, P.R. China, liuchenlqq@163.
identicalwiththetheoreticalcontrolstate,whichachievesthecontrolofthe com)
semi-active muffler. According to the analysis of the testing results, the
muffler has a good noise reduction effect to low frequency noise and the Inthispaper,thesoftwareFLUENTisusedassimulationtool,andthe
harmonicfrequencynoisecorrespondingtothelowfrequency.Itshowsan two-dimensional time-domain Computational Fluid Dynamics (CFD)
averagenoisereductionof10dBaswellasthemaximumnoisereduction approachisemployedtocomputethesoundreflectioncoefficientofcircular
approachingto35dB,whichrevealstheexcellentnoisereductioncharacter- ductwithoutandwithgasflow.Intheabsenceofmeanflow,thepressure
isticofthemuffler. far-fieldboundaryconditioncouldbeusedasnon-reflectingboundarycon-
dition in Fluent, and good agreement between the CFD prediction and
11:20 experimentmeasurementavailableintheliteratureisobserved.Forthecase
with gas flow, the general non-reflecting boundary condition is available
1aEA6.DesignofcompartmentalsilencerforHVACsystem.Y.H.Chan
onlywiththedensity-basedsolver(high-speedcompressiblefloworStrong
(DepartmentofMechanicalEngineering,TheHongKongPolytechnicUni-
couplingflow)inFLUENT,anditisdifficulttoacquiretheconvergentsolu-
versity, Hong Kong, China, [email protected]), Y. S. Choy, and
tionforthecalculationthatthedensity-basedsolverisusedtocomputethe
R.C.K.Leung
reflectioncoefficientofcircularpipe.Therefore,thenon-reflectingboundary
Airconditioningandventilationsystemisthemajornoisesourcesinthe conditionisnotappliedinthemodel.Thecomputationalresultsfromtime-
commercial building. Noise will be propagated from fan and through the domainCFDapproachbasicallyagreewithexperimentalresultsavailablein
associatedductworkintoworkingarea.Inordertoreducethenoisetrans- theliteraturewithgasflow,buttherearesomediscrepanciesatlowfrequen-
mitted, varies type of silencers can be placed in the ductwork to absorb cies. Finally,the effect ofobliqueterminationonthethesoundreflection
noiseorreflectthembacktothesource.Usuallythedominantnoiseislow- coefficientofcircularductisstudiednumericallyanddiscussed.
MONDAYMORNING,14MAY2012 S226,11:00A.M.TO12:40P.M.
Session1aED
EducationinAcoustics:TeachingAcousticsonBothSidesofthePacificI
SiuKitLau,Cochair
[email protected]
PrestonS.Wilson,Cochair
[email protected]
XiaojunQiu,Cochair
[email protected]
InvitedPapers
11:00
1aED1.ComparingtwoacousticsdegreeprogrammesinChinaandUK.Y.W.LamandF.F.Li(AcousticsresearchCentre,Univer-
sityofSalford,Salford,GreaterManchesterM54WT,UK,[email protected])
Withthecurrenttrendofeducationglobalisation,thepastdecadehasseenatideofstudentmigrationandexchangesacrossthePa-
cificOcean,evidencedbyalargenumberofstudentsfromAsia-Pacificregionspursuingtheiruniversitydegreesoverseas.Comparatives
pedagogical studies become timely, especially in niche science and engineering disciplines that tend to have rigorously specified
3213 J.Acoust.Soc.Am.,Vol.131,No.4,Pt.2,April2012 Acoustics2012HongKong 3213
prerequisitesthatarelikelytoimposechallengesonstudentexchangeandthedesignofjointprogrammes.Takingacasestudyapproach,
thispapercomparessyllabiandpedagogicalpracticesinacousticsdegreeprogrammesbetweentworepresentativeandreputableinsti-
tutesinChinaandtheUK,withtheaimstopromotegoodpractice,suggestnecessaryharmonisationofsyllabiinordertofacilitatestu-
dentexchangeandpossibleexchangeandjointprogrammeschemes.Thisshouldbeofinteresttothosewhoteachacousticsandrelated
subjectsinhighereducationorstudentswhointendtoparticipateinanexchangeprogrammetostudyabroad.Theresultfromthisstudy
showsthatthecurrentacousticsdegreeprogrammesinChinaandinUKaregenerallycompatible.Howeverdiscrepanciesinpedagogi-
calapproachesandthecommandofforeignlanguage(s)meanthatstudentswillneedtobepreparedtoquicklyadapttoa different
environment.
11:20
1aED2.Incorporatingreal-worldmeasurementandanalysisexperiencesintheteachingofadvancedacoustics.ScottD.Sommer-
feldt,KentL.Gee,andTracianneB.Neilsen(BrighamYoungUniversity,Provo,UT84602,[email protected])
Intheteachingofadvancedundergraduateandgraduate-levelacoustics,rigorousmathematicalpresentationandextensivehome-
worksetsarethenorm.However,studentsoftenfailtoseetheconnectionbetweentheoreticalmodelsandappropriateapplicationto
“real-world”situations.Consequently,effortshavebeenmadeincoursesatBrighamYoungUniversitytofindcollaborativemeasure-
mentandanalysisopportunitiesthathelpbridgethisgap.Althoughthiseffortisstillinitsinfancy,threeexamplesarediscussedinthis
paper.Thefirstwasmeasurementsofskateboardingparknoiselevelsinanearbyneighborhood.Thesecondinvolvedanalysisofthe
soundsystemandcrowdnoiselevelsinsideandoutsidetheBrighamYoungUniversityfootballstadium.Thethirdexamplediscussed
wasagraduatecourseprojecttoassessfeasibilityofcreatingactivezonesofsilenceinadatacenter.Lessonslearnedbystudents(and
faculty!)aredescribed.
11:40
1aED3.ThecourseofTheoreticalAcousticsinGraduateUniversityofChineseAcademyofSciences.HailanZhang(Instituteof
Acoustics,ChineseAcademyofSciences,StateKeyLaboratoryofAcoustics,Beijing100190,China,[email protected])
TheoreticalAcousticshasbeenacourseinGraduateUniversityofChineseAcademyofSciencessinceitwasfoundedin1978.The
coursecoversbasictheoriesofvibrationandacoustics.The120hourcourseisgivenin2termsofthefirstyear.Everyyear50-60stu-
dentsfromdifferentinstitutesattendthecoursewithdifferentmathematicalandphysicalbackground.Onefeatureofthecourseisthe
applicationofthefunctionalanalysistheory.Thecommongroundofthevibrationofthecoupledmultifreedomsystem,string,mem-
braneandroomisextractedandauniformtheoryofvibrationispresentedintheformoftheoperatortheory.Besides,manynumerical
resultsofacousticfields,especiallythetransientfields,giveninthecourseprovidemoreintuitiveunderstandingandhelpstudentslearn
thephysicsbetter.
12:00
1aED4.Telecom,ElectroacousticsandAudio(TEA)educationintwoprestigiousuniversitiesinTaiwan.MingsianR.Bai(Power
MechanicalEngineering,NationalTsingHuaUniversity,Taiwan,[email protected])
Thispresentationgivesanoverviewoftheacousticseducationbytheauthor’s21-yearcareerinNationalChiao-TungUniversity
andNationalTsingHuaUniversityinTaiwan.Althoughitisgenerallyrecognizedthatacousticsisan“old”subjectinclassicalphysics,
itfindsmanynewapplicationsinthemodernworld.Theparadigmofacousticeducationoftheauthoristogearthedomainknowledge
ofacousticstotheneedsofmain-streamindustriesinTaiwan,includingComputer,Community,ConsumerelectronicsandCar,theso-
called4Cindustries,withemphasisplacedupontelecomacoustics,eletroacousticsandaudiosignalprocessing(TEA)involvedinthe
4C products. To meet the ever changing challenges, a multidisciplinary approach including signal processing and control system is
exploited,inadditiontoacoustics,inthepedagogicmethodology.Itishopedthat,withthesenewperspectives,classicalacousticscan
berejuvenatedwithinunifiedframework.Intheauthor’scareerineducation,morethan100(including30inJASA)journalpapershave
beenpublished,aninstituteofSoundandMusicInnovativeTechnology(SMIT)andtheTelecomacoustics,EletroacousticsandAudio
signalprocessing(TEA)laboratoryhavebeenlaunchedinNCTUandNTHU,respectively,andamonographonacousticarraysystems
iscurrentlyinpreparation.
12:20
1aED5.AcousticsattheGeorgiaInstituteofTechnology.EricaERyherd(WoodruffSchoolofMechanicalEngineering,Georgia
InstituteofTechnology,Atlanta,GA30332-0405,[email protected]),MardiCHastings,andJohnDoane(WoodruffSchool
ofMechanicalEngineering,GeorgiaInstituteofTechnology,Atlanta,GA30332-0405)
AcousticsatGeorgiaTechspansmultipleschools,includingMechanicalEngineering,ElectricalEngineering,AerospaceEngineer-
ing,BiomedicalEngineering,Psychology,Music,Physics,Mathematics,andArchitecture.Theprogrambeganover50yearsagoand
strengthenedconsiderablyinthe1960sand1970safterEugenePatronis,BenZinn,andAllanPiercejoinedthefacultyintheSchoolsof
Physics,AerospaceEngineering,andMechanicalEngineering,respectively.Sincethenhundredsofstudentsinacousticshavegraduated
andholdpositionsinacademiaandindustryaroundtheworld.CurrentlytheSchoolofMechanicalEngineeringhastwelveacademic
andeightresearchfacultywithprimaryinterestinAcousticsandDynamics.Areasofresearchincludearchitecturalacoustics,psycho-
acoustics,noisecontrol,environmentalacoustics,sustainablesystemsdesign,underwateracoustics,bioacoustics,ultrasonics,active/pas-
sivecontrol,fluid-structureinteraction,nonlinearacoustics,acousto-optics,micromachinedsensorsandactuators,vibrationofnonlinear
andfrictionalsystems,shockandvibrationisolation,structuralacoustics,wavepropagation,andstructuralhealthmonitoring.Masters
andPh.D.levelprogramsareofferedinadditiontovariousundergraduatecourses.ThedepthofknowledgeatTechfacilitatesavariety
ofcollaborations,allowingstudentsamulti-disciplinaryeducationinthescienceandapplicationofacoustics.Studentinteractionsare
furtherfacilitatedbyanumberoforganizationsoncampus,includingastudentchapteroftheASA.
3214 J.Acoust.Soc.Am.,Vol.131,No.4,Pt.2,April2012 Acoustics2012HongKong 3214
MONDAYMORNING,14MAY2012 S227,9:20A.M.TO5:20P.M.
M
Session1aHT
A
N.
O
HotTopics:3-DSoundI(Lecture/PosterSession) M
a
1
YangHannKim,Cochair
[email protected]
Jung-WooChoi,Cochair
[email protected]
InvitedPapers
9:20
1aHT1.AnalysisofKoreanhead-relatedtransferfunction.YongwonJu,YoungjinPark,DaehyukSon,andSeokpilLee(Structural
DynamicsandAppliedControlLab.Dept.ofMechanicalEngineering,KAIST,infi[email protected])
Itisnecessarytoconstructhead-relatedtransferfunctiondatabaseforrenderingandstudyingthreedimensionalaudio.Forthisrea-
son,manyresearchgroupshavetriedtodevelopaHRTFmeasurementsystemandtoconstructaHRTFdatabasefortheirresearch.
EventhoughtherearevariousHRTFdatabases,thereisnodatabasewithanthropometryinpublicdomainaimedatKoreansevenifthe
HRTFsvarybasedonphysicalshapesofsubjects.BecauseKoreanshearthreedimensionalsoundrenderedbyHRTFdatabasebasedon
Caucasians,performanceofthreedimensionalsoundmightbehindered.Toverifythispossibilityandremedythedrawbacksofestab-
lishedHRTFdatabase,constructionofnewHRTFdatabaseaimedatKoreanisneeded.ForconstructingHRTFdatabase,newHRTF
measuringsystemusingsinesweepsignalwasdevelopedandtheHRTFsfor10subjectsat49differentelevationand36differentazi-
muthsat5angularincrementsweremeasured.ByusingmeasuredHRTFs,theHRTFsaimedatKoreanswerecomparedwithCIPIC
HRTFdatabaseandanalyzed.
9:40
1aHT2.Reproductionofimmersivesoundusingdirectionalandconventionalloudspeakers.EeLengTanandWoonSengGan
(NanyangTechnologicalUniversity,[email protected])
Visualandaudiocuesplayveryimportantrolesin3Dmedia.Insuchmedia,3Dsoundeffectsallowgamedeveloperoramovie
directortopositionsoundeffectspotentiallyanywhereinavirtualspacesurroundingtheviewer.Hence,accuracyof3Dsoundiscritical
topreventanydegradationoftheoverall3Dexperience.Whiletherearemanybreakthroughsinthedisplaytechnology,3Dvisualcon-
tentisstilldeliveredwiththecurrentaudiosystems,whichdoesnotaccuratelydeliver3Dsound.Thislimitationisdirectlylinkedtothe
dispersivenatureoftheconventionalloudspeaker,andthereproduced3Dsoundmaybeperceivedtolacksharpnessinthespatialimag-
ingduetoreverberantnatureoftheroomacoustics.Foradirectionalloudspeaker,thereproduced3Dsoundmayseemtolackspacious-
nessduetolittleinfluencebytheroomacoustics.Sincemostoftheloudspeakersinexistingsoundsystemaredispersiveinnature,3D
audioimagetendstobedegraded.Tosolvethisproblem,weproposeauniquesetupwhichcomprisesofconventionalanddirectional
loudspeakers.Thissetupexploitshighdirectivityofdirectionalloudspeakerstorecreateahighquality3Dsoundandtorecreatethespa-
ciousnessoftheaudiousingtheconventionalloudspeaker.
10:00
1aHT3. Perceptual control of convolution based room simulators. Markus Noisternig, Thibaut Carpentier, and Olivier Warusfel
(IRCAM-UMRCNRS,1placeIgor-Stravinsky,75004Paris,France,[email protected])
Reverberationprocessinghasbeenintensivelystudiedinaudioandacousticsresearchformanyyearsnow.Earlyapproachesused
feedbackdelaynetworkstocontrolthetemporaldistributionofreflectionsandtosimulatethestatisticalpropertiesofroomreverbera-
tion.Thankstotheincreaseinprocessingpowerandthedevelopmentoflow-latencyconvolutionalgorithmsanewgenerationofrever-
berationprocessorshasbeendeveloped.Theyapplyroomimpulseresponses(RIR)measuredinrealconcerthallsandthusguarantee
naturalnessandauthenticityofreverberation.Extendingthisapproachtotheuseofhigher-ordersphericalmicrophonearraysprovides
themeansforanalyzingthespatiotemporaldistributionofacousticenergy.Thisspace-time-frequencyrepresentationoftheacoustic
wavefieldisalsoreferredtoasdirectionalroomimpulseresponses(DRIR)inliterature.Theobjectiveofthepresentedworkistode-
velopaperceptuallymotivatedsignal-processingenvironmentbasedontheanalysisandre-synthesisofDRIRs.Itfirstextractspercep-
tual features from measuredDRIRs (e.g. sourcepresence and listener envelopment) and thusprovidesa perceptual signatureof the
measuredroom.Theroomacousticbehaviorcanthenbemodifiedalongthevariousperceptualdimensions,preservingthemicrostruc-
tureoftheoriginalRIRs,beforebeingre-synthesizedfortheusewithreverberationprocessors.
3215 J.Acoust.Soc.Am.,Vol.131,No.4,Pt.2,April2012 Acoustics2012HongKong 3215
10:20
1aHT4.Perceivedelevationofsimultaneouslypresentedsoundsourcesdependsuponthecorrelationbetweenthesourcesignals.
WilliamL.Martens(FacultyofArchitecture,DesignandPlanning,TheUniversityofSydney,NSW2006,william.martens@gmail.
com),andDensilA.Cabrera(FacultyofArchitecture,DesignandPlanning,UniversityofSydney2006)
Speechstimuliwerepresentedfrompairsofloudspeakersplacedatmatchedazimuthanglesoneithersideofthelisteningposition
inananechoicchamber.Theelevationanglesoftheloudspeakerpairswaseither10degreesbelowearlevel,10degreesaboveearlevel,
or30degreesaboveearlevel.Anadditionalloudspeakerwasplaceddirectlyabovethelisteningpositiontoserveasareferenceforan
elevationestimationtask.Asthecorrelationbetweensimultaneouslypresentedpairsofloudspeakersignalsreproducedatacommonele-
vationanglewasdecreased,theauditorysourcewidthincreasedtocreateabroadauditoryimagethatspreadouthorizontally,buthada
welldefinedapparentelevationangle.Theelevationanglesreportedforthesebroadauditoryimagesincreasedwithanincreaseinthe
correlationbetweenpairsofsimultaneouslypresentedspeechsoundsources.Theseresultshaveimplicationsforhowtocontrolmost
accuratelythedirectionofmultiplesourcespresentedover3-Darraysofloudspeakers,distributedverticallyaswellashorizontally.
10:40–11:00Break
11:00
1aHT5.Investigatingphysicalparametersassociatedwithlisteners’perceivedauditorydepth.SungyoungKim(Sound&ITDevel-
opmentDivisionYamahaCorporation,[email protected]),HirakuOkumura,andMakotoOtani
Recent3Dtechnologiesallowviewerstoperceivedisparitiesinthedepthsofvisualobjectsandtothusexperiencemorerealisticvis-
ualinformation.Asfor3Dauditorydisplay,however,conventionalloudspeakerlayoutshavenotmanagedtomanipulateperceivedau-
ditorydepthinasufficientlyconvincingway.Previously,weproposedanewmethodthatutilizesaprototypeelectrostaticloudspeaker
thatislocatedabovethelisteningpositionandgeneratesauditoryimagessimilartothoseofheadphones.Usingthisphenomenonand
amplitude-basedpanning,wewereabletomoveauditoryimagesalongthelineconnectingthefrontloudspeakerandthelisteningposi-
tion.Inthisstudy,weinvestigatedphysicalfactorsthatwereidiosyncraticinelectrostaticloudspeakerreproductionandthatcausedlis-
tenersto perceive soundsas being nearby.We bothmeasuredand simulatedtheloudspeaker-to-ear transfer functionsusingvarious
types of loudspeakers at multiple locations, and extracted several physical parameters, including the InterAural Phase Difference
(IAPD)andtheInterAuralLevelDifference(IALD).Theresultrevealedanewphysicalquantitythatwasassociatedwithloudspeaker-
listenerdistance:varianceinphaseresponsedifferentials.Weconcludethattheelectrostaticloudspeakerproducedrelativelylessvar-
ianceinphaseresponsedifferentialsandallowedlistenerstoperceivenearauditoryimagesasiflisteningtoheadphonesandtoenjoy
betterintegrated3Dcontent.
11:20
1aHT6.Dual-layerloudspeakerarrayformultiplelisteningzones.FilippoM.Fazi,FabioHirono,andPhilipA.Nelson(University
ofSouthampton,UniversityRoad,SO171BJ,Southampton,UK,[email protected])
Adual-layerarrayconsistingofsixteensmall(100)loudspeakershasbeenbuiltforsimultaneoustransmissionofaudiosignalstomul-
tiplelistenersoccupyingdifferentregionsofthespace.TheaudiosignalsarefilteredthroughabankofFIRfilters,computedusinga
LeastMeanSquares(LMS)approachwithregularization.Theplantmatrixofthearray,representingthetransferfunctionsbetweenthe
loudspeakersandasetofcontrolpoints,wasmeasuredintheanechoicchamberoftheISVRandwasusedinthefiltermatrixcalcula-
tion.Itisshownthattheselectionofboththenumberandlocationofthecontrolpointshasdirectimpactontheconditionnumberofthe
plantmatrix,onthefrequencyresponseofthedigitalfilters,onthefrequencyresponseofthereproducedsignals,andontheacoustic
radiationpatternofthearray.Resultsareshownforseveralapplicationcases,whichdemonstratealsothecapabilityofcontrollinginde-
pendentlythesoundradiationtothefrontandtothebackofthedual-layerarray.
11:40
1aHT7.Roleof4-8kHzbandcomponentforwidebandnoiselocalizationinmedianplane.YukioIwaya,TetsuMagariyachi(Res.
Inst.ofElect.Comm.,TohokuUniversity,2-1-1Katahira,Aoba-ku,Sendai,Miyagi,Japan,[email protected]),MakotoOtani
(ShinshuUniv.,4-17-1Wakazato,Nagano,Nagano),andYoˆitiSuzuki(Res.Inst.ofElect.Comm.,TohokuUniversity,2-1-1Katahira,
Aoba-ku,Sendai,Miyagi,Japan)
Whenwelocalizeasoundimage,interauralcues,suchasinterauralleveldifferencesandinterauraltime/phasedifferences,areused
inhorizontalplane.Ontheotherhandinmedianplanelocalization,spectralcuesaremoreimportantthanthatofinterauralcues.How-
ever,concretespectralcuesinvolvedinhead-relatedtransferfunctionsarenotsufficientlyinvestigated.Toclarifyspectralcuesofsound
localizationinamedianplane,weconductedasoundlocalizationtestwithbroadbandnoiseswithfrequencyspectrummanipulation.
Thenoisesweregeneratedbasedonapinknoiseandmodifiedsothattheyhadvarious1oct.bandlevels(-6,-3,0,+3,and+6dB)in4-
8kHzband.Thenoiseswereradiatedviatwoloudspeakerslocatedat30and60degreesofelevations,respectively,inthemedianplane.
Nevertheless,theperceivedelevationwasshiftedaccordingtothebandlevels.Thechangesofperceivedelevationresembledthoseof
relativepowerlevelsinhead-relatedtransferfunctions.Thissuggeststhattherelativelevelofthisbandinthehead-relatedtransferfunc-
tionswouldbeoneofspectralcuesforelevationperception.
3216 J.Acoust.Soc.Am.,Vol.131,No.4,Pt.2,April2012 Acoustics2012HongKong 3216