手機(jī)音腔和出音孔的設(shè)計(jì)計(jì)算

OptimalSoundMatchingSolutionthroughHelmholtz

resonatortheoryBasictheory HelmholtzResonatorwasinventedforsoundanalysisbyH.VONHelmholtz(1821~1894) Itsapplicationsarevariousfrombell,violin,guitarandbassspeakercabinet. Itfeaturesshorterneckandvolumebottlethanwaveasshownbelow. Specificfrequencydependsonairvolumeinneck(weight)andvolumeinthebottle(spring) Sospecificfrequencyiscalculatedasbelow.

a

:Neck’sarea(㎡)

V:Resonatorvolume(?)

L:Neck’slength(m)

C:Soundvelocity(344m/s)

ThereforeanyshapesofresonatorisnotaffectingResonantFrequency. Ifthevolume&neck’slengthissame,theresonatorhassameresonantfrequencyevenindifferentshape.BasicprincipleOptimalSoundMatchingSolutionthroughHelmholtz

resonatortheoryEx.1)What’stheresonantfrequencyincaseofabottlewithouterdia.9.8cm,necklength10cm,neckouterdia.3cm?ExampleOptimalSoundMatchingSolutionthroughHelmholtz

resonatortheory2.Application

(1)Insidestructureofhandseta:Holetotalarea(m2)SpeakerLCASEV:FrontVolumea:AirHoleBackVolumeL:Casethickness(m)V:Frontvolume(m3)C:344m/s(RT20℃)ApplicationOptimalSoundMatchingSolutionthroughHelmholtz

resonatortheory(2)Examplemodel:SS1534P-008-SIZE:Φ15mmX3.4H-Fo:850Hz-Ze:8ohm(3)Testconditions*Inputpower:0.1Wat5cmBasicprincipleOptimalSoundMatchingSolutionthroughHelmholtz

resonatortheoryBKMode:TSRA:FrequencyResponse,MagndBre20.00Pa/V1002005001k2k5k10kHz60708090100110dBX:900.00HzY:98.92dBZA:LiveCurveTSRfund.SS1534P-008GRAPHinBAFFLEOriginaltestresultOptimalSoundMatchingSolutionthroughHelmholtz

resonatortheory(4)TESTaccordingtosomevariations ①BasicStructure ②AirHolequantityvariation ③Casethicknessvariation ④FrontVolumevariation ⑤BackVolumevariationTestconditionOptimalSoundMatchingSolutionthroughHelmholtz

resonatortheory

①Basicstructure

a:Φ1.55mmX4eaL:1.55mmV:1.2ccC:344m/s(RT20℃)Backvolume:2.42cc

=3,486HzBasicstructureHandSetMatchingSolutionwithHelmholtz

resonatorSpeakerLCASEV:FrontVolumea:AirHoleBackVolumeX:3.0000kHzY:104.23dBZA:LiveCurveTSRfund.BKMode:TSRA:FrequencyResponse,MagndBre20.00Pa/V1002005001k2k5k10kHz60708090100110dB3,486Hz3,000HzTestresultOptimalSoundMatchingSolutionthroughHelmholtz

resonatortheory

②AirHolequantityvariation

a:Φ1.55mmX4eaΦ1.55mmX2eaL:1.55mmV:1.2ccC:344m/s(RT20℃)Backvolume:2.42cc

=2,465HzAirholevariationOptimalSoundMatchingSolutionthroughHelmholtz

resonatortheorySpeakerLCASEV:FrontVolumea:AirHoleBackVolumeBKMode:TSRA:FrequencyResponse,MagndBre20.00Pa/V1002005001k2k5k10kHz60708090100110dBX:2.4000kHzY:101.47dBZA:LiveCurveTSRfund.2,465Hz2,400HzTestresultofairholechangedHandSetMatchingSolutionwithHelmholtz

resonator

③Casethicknessvariation

a:Φ1.55mmX4eaL:1.55mm2.5mmV:1.2ccC:344m/s(RT20℃)Backvolume:2.42cc

=2,745HzCasethicknesschangedOptimalSoundMatchingSolutionthroughHelmholtz

resonatortheorySpeakerLCASEV:FrontVolumea:AirHoleBackVolumeBKMode:TSRA:FrequencyResponse,MagndBre20.00Pa/V1002005001k2k5k10kHz60708090100110dBX:2.6000kHzY:102.29dBZA:LiveCurveTSRfund.2,745Hz2,600HzTestresultbycasethicknessvariationOptimalSoundMatchingSolutionthroughHelmholtz

resonatortheory

④FrontVolumevariation

a:Φ1.55mmX4eaL:1.55mm V:1.2cc0.8ccC:344m/s(RT20℃)Backvolume:2.42cc

=4,269HzFrontvolumevariationOptimalSoundMatchingSolutionthroughHelmholtz

resonatortheorySpeakerLCASEV:FrontVolumea:AirHoleBackVolumeBKMode:TSRA:FrequencyResponse,MagndBre20.00Pa/V1002005001k2k5k10kHz60708090100110dBX:3.9000kHzY:105.25dBZA:LiveCurveTSRfund.4,269Hz3,900HzTestresultbyfrontvolumevariationOptimalSoundMatchingSolutionthroughHelmholtz

resonatortheory

⑤BackVolumevariation

a:Φ1.55mmX4eaL:1.55mmV:1.2ccC:344m/s(RT20℃)Backvolume:2.42cc1.5cc

BackvolumevariationOptimalSoundMatchingSolutionthroughHelmholtz

resonatortheorySpeakerLCASEV:FrontVolumea:AirHoleBackVolumeBKMode:TSRA:FrequencyResponse,MagndBre20.00Pa/V1002005001k2k5k10kHz60708090100110dBX:1.3000kHzY:96.65dBZA:LiveCurveTSRfund.LossoflowsoundTestresultbybackvolumechangedOptimalSoundMatchingSolutionthroughHelmholtz

resonatortheory3.ConclusionWecometoconclusionthroughprovedtheoryasfollows:1)Thequantityoffrontairhole↓,ResonantFrequency↓2)Frontcasethickness↑,ResonantFrequency↓3)Frontvolume↑,ResonantFrequency↓4)Backvolume↑,Lowsound↑OptimalacousticsolutioninhandsetdesigncanbecomingfromHelmholtzresonatortheory.Incasethatspeakeritselfhasflatfrequencyresponse,specificresonantfrequencyisgeneratingwhenbeingmountedinthehandset.ThenSPLandsoundqualityisdependingonhowtheresonantfrequencyismetwith.Inconclusiontheoptimalresonantfrequencyshouldbesetbetween2KHzand5KHzbecausetheseareaismostsensitiv