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1、汽车检测线专项训练5-朱明zhubob学生作业Section8autodetectionofnoiseasaseriouspublichazardhasincreasinglyarousedpeople'sconcern,atpresent,theworldhas,thenoisecontrolstandardinsuccession.Thegeneraldefinitionofnoiseisthecombinationoffrequencyandsoundandnoise,resultingintheimpactonpeoplean
2、dtheenvironment.Amorehumanedescriptionisthatpeopledon，tlikethesoundofnoise.Carnoisehasbecomethemainsourceofnoiseinsomebigcitiesascarsdeveloprapidlyandhighpower.Carnoisemainlyincludesenginenoise,combustionnoise,exhaustnoiseandfannoise.Chassisofbrakenoiseandmechanicalnois
3、e,tirenoise,vibrationnoiseofthetrain,thegoodsimpactnoise,hornandsteering,whilebackinghumnoise.Becausethevehiclenoisehastheabilitytotravel,theinfluenceislarge,theinterferencetimeislong,sotheharmisgreater.First,theevaluationindexof1.Thenoisesoundpressureandsoundpressurele
4、velofthenoiseofthemainphysicalparameterswithsoundpressureandsoundpressurelevelandsoundintensityandsoundintensityandpowerlevelandsoundpowerlevel.Thesoundandpressurelevelsarethemostbasicparametersforastrongvoice.Soundpressureisthevariationofpressureintheelasticmediumbecau
5、seofthepresenceofsoundwaves.Thestrengthofsounddependsonthesoundpressure,thelouderthesoundthelouderthesound.Thehumanearcanhearthesoundpressurerangeis2x10-5(auditorythresholdpressure)〜20pa(painthresholdpressure),adifferenceof1milliontimes,sousetheabsolutevalueofsoundpress
6、uresaidtheywouldfeelthestrengthofthevoiceisnotveryconvenient,sopeopleoftenusethestrengthofthesoundpressureleveltorepresentsound.Thesoundpressurelevelistheratioofthesoundpressureatapointtothebasesoundpressure(thethresholdsoundpressure)POThevalueoftheunitisdB(dB).Theaudib
7、lepressurerangeis0~120dB.Thesoundofthespectrumofnoiseisnotonly-relatedtosoundpressure,butalsotothefrequencyofsound.Thefrequencyrangeofaperson，searis20〜20000Hz.Thesoundsourceisnotthesoundofasinglefrequency,butacomplexsoundwithmanyfrequencies.Soundsmakeabigdifferencebecau
8、seoftheircomposition.Therefore,inordertofullyunderstandthecharacteristicsofasoundsource,onlyknowitunderacertai
