Dean Ayers (Dept. of Physics and Astron., California State Univ., Long. Beach, CA 90840) .... In an attempt to simulate guitar sounds, a discrete model was devel-.
nasalityand (2) itscomplement,rich/brilliant; thesearecorrelatedwith total harmonic distortion, which in turn is connectedto the lattice tone-
holecutofffrequencies. Cepstraldistances of dyadspectrahavea weak correlationwith perceptualdistances;however,the clusteranalysesof perceptual distances andcepstraldistances providesimilardyadpairings and orderings.Evidencesuggests that individualspectralcontributions vary by instrumentcombination.This demonstrates that meremixturesof separately recordedvoicesaredifferentacoustically fromthoseof ensemble playing.
were analyzedfor possiblecorrelationswith musicians'preferences as obtainedfromplayingtests.It wasoriginallybelievedthat intonationisan importantcriterionfor a goodbrasswind instrumentandits mouthpiece, but it was not clearly evidentfrom the data. Other parametersof the responsecurvesanalyzedincludedimpedancepeak amplitudesand Q ratios.
3:30
2:45
9MU5. Optimizationof clarinettone holes.Ji Lu Feng and William J. Strong(Dept. of PhysicsandAstron.,BrighamYoungUniv., Provo, UT 84602)
Intonationand stabilityof clarinettonesare influencedby the resonancefrequencies of the instrumentthat are influencedin turn by the placementand sizeof its toneholes.Dimensionsof an instrumentof moderatequalityweremeasuredandservedasthestartingpointfor the optimization procedure.Input impedanceswere calculatedfor 47 different fingeringsof the instrument.Minimizationof the frequencydifferences betweenfour resonancefrequenciesNmodes 1 and 2 in the chalumeau register,mode2 in the clarionregister,andmode3 in the altissimoregisterNand four referencefrequenciesservedas the optimizationcriteria. The reference frequencies werearbitrarilychosen fromanequaltempered chromaticscaletunedto A4 = 440Hz. Tone-holeposition,diameter,and heightwerethe optimizationparameters.In one method,theseparameters were modified one at a time, while in a secondmethod all three were
modifiedtogether.Both methodsproducedsimilarresultswith average reductionsin "frequencyerror" of 9 centsfor chalumeaumode1, 28 cents
9MU8. A 19th centurytrumpetin F. RichardP. Birkemeier(Dept. of Music, California State Univ., Long Beach, CA 90840) and R. Dean Ayers(Dept. of PhysicsandAstron.,CaliforniaStateUniv., Long Beach, CA 90840)
Thereisa tendencythesedaysto thinkof"the trumpet"asthefamiliar brassinstrumentseencommonlyin orchestras andbands.In reality,the instrumentthat is now calledthe trumpetis a hybrid designthat more closelyresemblesthe old band instrumentcalledthe cornet.The last true
trumpetdisappeared from the musicalscenealmost100yearsago.This instrument wasbuiltwitha majorityofcylindricalboretubing,waslonger in overalllengththanthemoderninstrument,andwaspitchedin F. One exampleis thismodelmadeby Courtoisand Mille of Parislate in the 19th
century.The tonecolorisdifferentfromthatof themoderntrumpet,and it hassomespecific performance problems, butdespiteitslowerpitch,this wasthe sopranobrassinstrumentpreferredby composers of a century ago.A comparison with themoderntrumpetin termsof responses in the time and frequencydomainswill be correlatedwith live demonstrations. [Work supportedin part by a CSULB SummerResearchGrant and EquipmentGrants from Hewlett-Packard. ]
for chalumeau mode 2, and 16 cents for modes 2 and 3 of the combined
clarionand altissimoregisters.Optimizationprocedures and resultswill be discussed. 3:45
9MU9. Progressreport on a pulsetechniquefor wind instrumentbores. Dale R. Stanbridgeand R. Dean Ayers (Dept. of Physicsand Astron., CaliforniaStateUniv., Long Beach,CA 90840) 3:00
9MU6. Interfamily timbrai differences:A comparisonof tromboneand flute tone spectra.JamesW. Beauchamp(Schoolof Music, Univ. of Illinois, Urbana-Champaign,Urbana, IL 61801)
Time-averaged spectrafor tonesof thetromboneandfluteperformed at thesamepitchcanbequitesimilar[ D. A. Luce,J. AudioEng.Soc.23, 565-568 (1975) ], and yet the tonessoundquitedifferent.Besidesfactors of attackrateandnoisecontent,strongdifferences betweenthetwotypes of soundscanbeobserved dueto themannerin whichpartialamplitudes changeasa functionof overall(rms) amplitude.As rms amplitudeincreases,trombonepartial amplitudesincreasesmoothly,resultingin an increasing spectralcentroid,andasrmsamplitudedecreases, theyfollow approximatelythe samecurves.On the otherhand,amplitudesof flute partialstendto "turn on" at certainthresholds, depending on performed attackandoverallamplitude,andfollowdifferentcurvesduringascending and descending portionsof the tone. Usinganalysisand synthesis techniques,it is possibleto createhybrid tonesthat blend someof the
The piezoelectric driverdiscussed by A. H. BenadeandM. I. Ibisi [ J. Acoust.Soc.Am. 81, 1152-1167(1987) ] hasbeenemployedasa pulse generatorby usingWienerfilteringto shapethe appliedvoltage[E. A. Robinson,MultichannelTime SeriesAnalysis(GoosePond, Houston, TX, 1983), 2nd ed.]. Severalrefinements havebeenimplementedsince thistechnique wasfirstdescribed [Ayersetal., J.Acoust.Soc.Am. Suppl. 1 77, S90(1985) ]. Instrumentalimprovements includetheuseof a Spectral DynamicsSD380 spectrumanalyzeranda Hewlett-Packard 330SPU workstation.Timeaveraging andfurthercompensation for low-frequency noisenow yieldcleanerresultsin bothtime and frequencydomains. Reflectionimpulseresponses and transferfunctionsare foundwith a singlemicrophone ona longpipe.Inputimpedances andtheircorresponding Green'sfunctionsare obtainedby comparinga bore'sresponse with that of a uniformpipeontheothersideof thedriver.[Work supported in part by a CSULB SummerResearchGrant andEquipmentGrantsfromHewlett-Packard. ]
characteristicsof the flute with thoseof the trombone,in order to evaluate the perceptualimportanceof distinctiveparameters. 4:00
9MU10. Wavelet methods for estimation of acoustically relevant 3:15
9MU7. A comparison of musicians' preferences and acoustic measurements of differentFrenchhornmouthpieces. GeorgeR. Plitnik ( PhysicsDept.,FrostburgStateUniv., Frostburg,MD 21532) andBruce A. Lawson (Lawson BrassInstruments,Inc., Boonsboro,MD 21713)
Impedancemeasurements weremadefor a selection of commercially sold mouthpiecesattachedto a test French horn. The resultantcurves
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parameters of musicalsignals.R. Kronland-Martinet, a) Ph. Guillemain (CNRS-LMA andFacultedessciences deLuminy,31 cheminJ. Aiguier, 13402 Marseille, France), and A. Grossmann (CNRS-CPT Faculte des sciencesde Luminy, 13288 Marseille, France)
Wavelet transformsare a classof analysisand resynthesis methods that havebeenfoundusefulin a varietyof domains[ Wavelets, editedby J. M. Combes,A. Grossmann,and Ph. Tchamitchian (Springer-Verlag, IPTI, 1989)]. They providea two-dimensional (time andscale)descrip-
120thMeeting: Acoustical SocietyofAmerica
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Cedex 13, France and KTH, Dept. of SpeechCommun. and Music
tionof one-dimensional signals.In thispaper,wavelettransformsareused as the basisfor an algorithmthat representsan audiosignalas a sumof "spectralcomponents"(contributionsobtainedby amplitudemodulation and slow frequencymodulationarounda frequency).A centralrole in thisconstructionis playedby the phaseof the (complex-valued)wavelet transform;theinterpretationof thisphaseisparticularlysimpleandintuitive if the analyzingwaveletis chosenas an analyticsignal(progressive wavelet).The parametersdeterminedby the algorithmallow an additive reconstructionof the signal,as well as a variety of nonlinearmodifications. Thesepossibilitieswill be illustratedby severalaudio examples.
Acoust., Box 70014, S- 100 44 Stockholm, Sweden)
In an attemptto simulateguitar sounds,a discretemodelwas developedthat consisted of real stringswith stiffness andinternaldamping,the player'sfinger, the resonancebox, and the modelizationof the sound pressure.The vibratingstring equationwas solvedin the time domain usingthe finite-differencemethod.The player'sfigurewasmodeledas a forcedensityterm in the stringequation,which accountedfor the initial pluckingconditions.The resonance box was modeledas impedancelike boundaryconditionsat oneend of the string.Theseend conditionswere obtainedunderthe assumption that thedrivingforceexertedby thestring at its endsexcitesa set of second-orderresonances in parallel,the first resonanceof the plate beingcoupledwith the air resonanceof the box. Finally, the soundpressurewasmodeledas the contributionof a set of monopoles,where eachmonopolecorresponds to one givenresonance. The radiationefficiencyof eachmonopolewasderivedfroma curvefitting on a guitar sound-pressure spectrummeasuredin an anechoicchamber. The waveformsobtainedare in goodagreementwith experimentalwaveformsmeasuredon real guitars.Soundexampleswill be presentedhighlightingthe realismof the simulation.
a)Currentaddress: StanfordUniv., CCRMA Dept. of Music,Stanford, CA 94305-8180.
4:15
9MUll. Computer processingof audio signalsby exclusionfilters. Robert C. Mahcr (Dept. of Elec. Eng., Univ. of Nebraska-Lincoln, 209N WSEC, Lincoln, NE 68588-0511 )
A commontaskin computermusicandelectroacoustic signalprocessingisadditivemixingof twoaudiosignals. If thetwoinputsignals contain discretespectralcomponents, theirsumwill typicallycontainamplitude beatingandotherinteractions betweenpairsof components with similar frequencies. A newmethodis described that suppresses spectralinteractionsduringmixingby derivinga timevariant"exclusion filter" fromthe short-timespectrumof oneof the signalsin orderto prefilterthe other signal.This techniqueallowsone of the signals(dominant) to pass throughthemixingprocess withlittlemodification, whiletheothersignal (secondary)isprevented frominteractionbyattenuation ofitsconflicting spectralcomponents. The exclusion filterisspecified in a flexiblemanner, which can includesuchpsychoacoustic criteriaas criticalbands.Audio
4:45
9MU13. Statistical analysisof old Serbian music.Milan J. Merkle and Miomir Mijic (Univ. of Belgrade,Faculty of Elec. Eng., P.O. Box 816, 11001Belgrade,Yugoslavia)
Beinga link betweenmathematicalscrutinyanda fuzziness of the real world, statisticsis oftenusedto helpinvestigaterelationsbetweenobjects or phenomenathat are intuitivelysimilar (or dissimilar).In theseproblems,statisticalmethodssetobjectivecriteria of similarity,thusreducing the humanproneness to errors.This work is an attemptto makea contributionto an objectiveanalysisof music.It is not quiteclearwhat are the main objectivecharacteristics of a musicalwork, and muchlessis known abouthow to translatethem to a mathematicalwriting suchthat when two songssoundsimilar, one getstwo numbersthat are closeto each other.This is a problemof coding.In thiswork, the problemof codingis investigated,and the powerof variousstatisticalmethodsin comparison of songsis demonstrated.This is•doneusingsamplesof an old Serbian chant from the 15th century. This kind of music is usedbecauseof its relativesimplicity.
exampleswill bc presented.
4:30
9MU12.
A
discrete model
for
synthesizing guitar
sounds.
Antoine Chaigne (TELECOM Paris, 46 Rue Barrault, 75634 Paris
FRIDAY
AFTERNOON,
30 NOVEMBER
1990
COUNCIL-CHAMBER
ROOM,
1:00 TO 2:40 P.M.
Session 9PAa
Physical Acoustics:Use of Acousticsin Electronics Yves H. Berthelot, Chair
GeorgiaInstituteof Technology, Schoolof MechanicalEngineering,Atlanta, Georgia30332 Invited Papers 1:00
9PAal. Acousticaspectsof acousticchargetransport devices.William D. Hunt (School of Elec. Eng., GeorgiaInst. of Technol.,Atlanta, GA 30332)
The Gallium Arsenide(GaAs)acousticchargetransport(ACT) devicewasfirstreportedin 1982 [M. J. HoskinsandB. J. Hunsinger,1982IEEE Uhrasonics Symposium Proceedings, IEEE CatalogNo. 82CH 1823-4 (IEEE, New York, 1982), pp. 456-460] and hasbeensubsequently developedfor a varietyof analogsignal
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120th Meeting:AcousticalSocietyof America
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