简介:Inthenormal-modetheoryofMorse,itgivesaseriesofnormalmodesasthesolutionofforcedvibrationinaroom.Butactuallythereisalwaysthedirectradiationbesidesthenormalmodeswhichrepresentthereverbrantsoundfieldonly.Thereasonisthatthenormalmodeswereassumedonlyinthesource,andnaturallynormalmodesonlyareobtainedinthesolution.Atheoryofdoublesourceisproposed,thatthesoundsourceisboththesourceofthedirectradiationasifinfreespacebeforetheboundarysurfaceswerereachedbythedirectradiation,andafterthefirstreflectionfromtheboundarysurfaces,thesourceofthereflectedwavelets,randomlydistributedbothinspaceanintimeontheboundarysurfacesthatbuildupthenormalmodesafterfurtherreflections.Thewaveequationisformedaccordingly,andthesolutionofthewaveequation,thesoundfieldinaroom,containsexplicitlyboththedirectradiationandthereverberantsoundformedofnormalmodes.Theapproximatemeansquaresoundpressureisfoundtobethedircetsounddeterminedbythesoundpowerofthesource,andreverberantsounddeterminedbythesoundpowerreducedbyafactorofπ/2,differentslightlyfromtheresultobtainedfromenergyconsideration,ifthesourceispuretone.Thereisessentiallynodifferenceforasourceofbandnoise.
简介:Anewapproachtothetheoryoffinite-amplitudestandingwavesinproposed,andfoumulasofsteadywaveformsarederivedfromthefundamentalequationsofhydrodynamios,asanendeavortosettlethelong-timedisputablesituation.
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简介:Intheconventionalanalogouscircuittheoryoftheloudspeakersystem,thevibratingairinboxisconsideredaslumpedparameter;inthispaperweconsidertheairasdistributedparameter.Thesoundfieldtheoryandtheanalogouscircuittheoryarecombinedtoanalyzethecharacteristicsoftheloudspeakersystemsuchasradiationacousticpower,frequencyresponseandimpedanceresponse.
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简介:AFeynmandiagramtheoryforacousto-optic(AO)interactionsisestablished,whichprovidesageneralmethodtocalculatethescatteringamplitudesandintensitiesforbothsingle-frequencyandmultifrequcncyAOinteractions.ThemethodisbasedoncountingthenumberofallowableFeynmandiagrams.Thefollowingimportantassertionhasbeenprovedrigorouslyinthispaper.TheratiosofthenumbersofFeynmandiagramsallowableinvariousBraggdiffractions(isotropie,nondegeneratcbirefringent,anddegeneratebirefringent)tothatinRaman-Nathdiffractionareindependentofthenumberofdifferentacousticfrequencies,beingafunctiononlyoftheorderoftheFeynmandiagramandthediffractionorderofthefinalstate.Generalexpressionsfortheseratiosarcobtained.Basedonthis,completeperturbationsolutionsforthescatteringamplitudesandintensitiesareobtainedforanykindofAOinteractions,anynumberofacousticfrcquencies,andanyfinalstate.Thistheorygivesallresultsobtain
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