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Chapter 8 Sound out of place（第1页）

Chapter8Soundoutofplace

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&ureofnoise

Whatishisisohosequestioistime?’，towhiightanswer:‘Iklywhatitisuntilsomeo’sworsethanthat，for‘woquitedifierentthings.Forastist，raneousacousticiergy.Whenusedforunioiseiswhateverisnotthesignal，inotherwordsdoesnotatioheinformationisavoiawire，orastructuralelementinanultrasonihelargertheamountofhemorediffcultitbeestouhesignalfromit—heofsignaltoio.

Onoisehasbeeifled，itbefairlyeasytoremove.Noiseinacircuitthatoccursatparticularfrequenfromamaiysupply，forexample）bedealtwithbyfllters，sothatonlyfrequeerestremain.Unfortunately，ironics，averyofenoise，asignalthatflllsallfrequeerestandsoundslikeahisswhehroughaloudspeaker.Thisotbefllteredoutsoeasily，butoeadfllterallbutthefrequendsthatcarrythesigillbewhitehosebands，butthenaltoiowillimprove.

Formostofusmostofthetimethough，‘noise’isanysoundwhiwahepersooit.Atrumpetermaybeverypleasedwithhisoutputaainlynotthinkofitasaneighbhtwelldisagree，howeverteicallyextitmaybe.Andbht—oneperson’smusiother’shisdisagreemeheveryheartofwhynoiseissodiffculttoquash.Butfortunately，whilealmosteverysoundhasatleastafewpeoplewholoveit，ahosetowhomalmostanythingbutsilehema，itisalsotruethatsoundswhiyofusthinkofasendtosharethreecharacteristiness，louduoflndoutwhythisisso，weosiderwhywehearanythingatall.

&rallegacies

Wehearbecauseouraorsdid，andtheyheardbecausetheirdeafrelativesdied.Amongthemanysoundswithwhichtheywouldhavebeensurrounded，afewweremattersoflifeah.Asuddenroar，thetwangofab，thesnapoftwigsuhecraderoverheadwerealldangersigns，andwhattheyhaveinonissuddeodayouriosuddennoise.Suddehehushredathted，meantasmuchassuddensoundahefamiliardeafeningsilenaclockstopstiairerswitchesofi，orpersistentrainsuddenlyfaexpegetothesoundsaroundusannoyingnoise:everydriverkionandcausedbyanewaiflableenginenoise，athetigermayopickoutatall，howeverwellthedriverimitatesit.

Butwhyareweahosesoundswhirelatedtoaralsoundthatmightsignaldaalkioutsideatmidnight?MP3playersyoujusthearacrossatraincarriage?

Theanswerliesinakeysoofsouepower，inparticularbygownershipofspace.Weareusedtotheideathateachofushasapersonalbubbleofspacethatwed，towhiinvitedareunweleonewhoispacewiththeirsoundsbeasannoyirudingintoitphysidthemainpointinbothexamplesisi.Howmunoyingisthepersonsittioyouiftheyphoalkhaniftheyreceiveacallofreal?

&herpersardedasnoisyoroooiohemaeoriansShaneandGrahamWhite，foriheirstudiesofslaveryintheUS，foundthatthesermonsofAfriAmerigelistpreachers，reciatedbygregations，werereferredtosimplyasnoisybywhiteAmeriswhowereedbecausethesounds，aheirmessagestoo，spreadfarbeyondtheesoftheirveuralanttoo:acceptablesoundlevelsinlibraries，duriimes，andatfuneralsvarygreatlyiries.

Theseaofotherpeople’snoiseinwhieisoftensubmergedonpublisport，inpublicspaces，oropen-planoffbeadisturbingeheindividualsouheridentifledheheariaodoboth，makingthemashardtoigoeswhenonedoesmaoignoresudsonasciouslevel，thementalprogues，asdoesthestressthatsometimesresults—andthehighbloodpressurethatthisstresscause.

&heonlywaytoree’sprivatesouoflllitwithasoundfleldofone’sownmaking，byuseofanMP3playerorsmartphtoMichaelBull，ProfessorofMediaandFilmattheUyofSussex（UK）:‘iPoduseusefullybeiedasaformofpleasurabletoxicitywithinwhiediated”

worldofusersliesadreamofuedexperience—ofdirectaccesstotheworldaions’.

Therearesomesoundswhiotbeighoughtheydonotreallyexist.Theseso-calledearwormsareusuallybriefsnatusibanalones，whisistthemselvesinthemiisingjinglesareespeingtheirwayin.Thoughsowidespreadandseeminglysimple，earwormsareactuallyveryhardtoexplaiOliverSackssuggeststhattheunusualwaymusicisrememberedmaybesigniflt.Regaseoreverugit，whimeansthattheresultmaybeverydifierenti‘replays’.Inregapieusic，however，somethingmuchclosertoadirectcopyinalispreserved，an‘almostdefengravingofmusithebrain’，

asSacksputsit，overwhichwehaverelativelylittletrol.Perhapsthefactthattunes，ahis‘engraving’process，arrivedsolateiionofthemindisareasonwhysuchmemoriesarehardtotrol.

Musihaveevenmoreprofouhemind—icauseepilepticseizures，whileihaveasignifltlygefiedalleviatepainandhighbloodpressure.Itbeespeciallyefiethetreatmealproblems，andhasbeehiswaysinceWorldWarII.MusichasalsobeenshowrelieftosomewhosufierfromParkinson’sdisease.

Deafening

Theproblem—iragedy—ofnoise-induglossisthatitmayilyearsafterthedamagehasbeendone.Also，whilewereactimmediatelythtemperaturesori，ourdefeonoisearefarpoorer.

Oureyesareequippedrotectiveadaptations，mostobviouslyeyelidsaingpupil（orexpandingiris）.Whydoestheearhavehereasonforthelackofearlidsisthatwhiledeafnessmayshortenananimal’slife，itwohinglikeasmugsuccessfullycreptuponbyahungrytiger.Andwedohaveahepupil，thoughit’snotparticularlyefiective:theacousticrefflexisprovidedbytwomuseachearcalledthestapediusaympani.Whenaloudsouapediuspullstheossiclecalledthestapes（‘stirrup’，sshape）awayfromtheovalhilethetensortympanipullsonthemalleus（hammer）ossicle，whichisattachedtotheeardrumaifieer.Asaresult，soundsaremufied.Thestapediususuallytenseswheopusannoyihourowensortympahesamejobpressourownoises.

&icrefflexisoemporarythresholdshift（TTS），inwhidswhichareusuallyquietbeeiuimetherefflextakestowork（calleditslatency）isusuallyaround45milliseds，whichisfarlotakesanimpulsesound，likeagunshotorexplosion，todosiderabledamage.TherefflexisoributortoTTS;theothermeismsarestillunknown.

&heoverburdenedeardifiersfromotherabusedmeasuringis（biologidteological）isthatitisnotonlytheSPLofters:estoo.Aalevelwhichwouldorethanirritatiooforaseleadtosigniflthearinglossifituesforanhour.TheamountofTTSisproportiohmofthetimeforwhioisehasbeeis，doubliimemorethaheamount.

However，veryloudimpulsesous，willalsostantdamage，evealenergyislow.（Reputedly，atrainedaudiologisttifythepermadamagecausedbyasiflredbyapatientrote.）Reesiheamountofshift;aTTSof40dBtakeweekstoreountofTTSredusiderablyifthereisapauseinthenoise，soifexposuretonperiodsisuafootballmatch，say），thereisverysigniflefltinremovihenoisyarea，ifonlyforflfteenminutes.

Itisontheevidenanycarefulexperimesofnoisethations，nowstatutoryinworkpladelsewhereinmanytries，havebeeheyplacelimitsbothonpeaknoiselevelsandduratioospecifledlowerlevels.

Ohidentifyingholehavenoiseinduglossisthateveryoythfrequendsdeeswithage:newborn，to20kHz，bytheageofaboutfortythishasfallentoaround16kHz，

andto10kHzbyagesixty.Agedeighty，mostofusaredeaftosouheefiectiscalledpresbyacusis（literally‘oldmanhearing’）.Sinoise-induglossusuallyalsoimpactshigherfrequend，beingcumulative，beonwithage，wedon’treallyknowhowmuchlossisavoidable.

Iftherehasbeenadowheoftenlaudableprogressmadeintagerouslyhighlevelsofhasbeeiveofnoisewhily’loudenoughtoanetheirvasthe2008IpsosMORI（UK）NationalNoiseSurveyfoundthat26pertofresposwereannoyedbyneighbournoise，forexample.Thoseafiectedlosesleep，theylosetration，theylosepatiehejoyfromtheirlives（39pertsaidtheirqualityoflifewasadverselyafiected）.Suoisealsoexacerbatesmehproblems，unitytensions，andsocialisolation.

Therearefeoulddenythatthebestapproachwouldbetoremoveheeheflrstplace.Howthise，aively，dependscruthesourostinhabitantsofthedevelopedworldandmahefollowingsourcesarelikelytobethemainones:

·Airtraffc

·Industrial

·Neighbour

·Neighbourhood

·Rail

·Roadtraffc

Inaddition，shippingnoiseandwind-farmsnifltly，whilemostareasareblightedbystrutimetotime.

Ofthesegroups，neighbhbourhoodicularlydiffculttodealwith，partlybecausethemakerdoesnotclassthemashelistehisdiffcultyhasledsoundhistorianKariocludethatementisinthegripofa‘paradoxoftrol’，inwhiisesofexpertsandpolitistooiseactuallyamounttopassioneighbourstodoso，ordevelopingsuplexformulaefotherformsofnoise，suchasthatfromaircraft，thatfewderstah，orcritiquethem.