【Ingeneral,itseemsreasonabletosupposethatweshouldpreferpeaceandquiettonoise.Andyetmostofushavehadtheexperienceofhavingtoadjusttosleepinginthemountainsorthecountrysidebecauseitwasinitially“tooquiet”,a】

　　Ingeneral,itseemsreasonabletosupposethatweshouldpreferpeaceandquiettonoise.Andyetmostofushavehadtheexperienceofhavingtoadjusttosleepinginthemountainsorthecountrysidebecauseitwasinitially“tooquiet”,anexperiencethatsuggeststhathumansarecapableofadaptingtoawiderangeofnoiselevels.Researchsupportsthisview.Forexample,GlassandSinger(1972)exposedpeopletoshortburstsofveryloudnoiseandthenmeasuredtheirabilitytoworkoutproblemsandtheirphysiologicalreactionstothenoise.Thenoisewasquitedisruptiveatfirst,butafteraboutfourminutesthesubjectsweredoingjustaswellontheirtasksascontrolsubjectswhowerenotexposedtonoise.Theirphysiologicalreactionsalsodeclinedquicklytothesamelevelsasthoseofthecontrolsubjects.

　　Buttherearelimitstoadaptationandloudnoisebecomesmoretroublesomeifthepersonisrequiredtoconcentrateonmorethanonetask.Forexample,highnoiselevelsaffecttheperformanceofsubjectswhowererequiredtomonitorthreedialsatatime,atasknotunlikethatofaplanepilotoranair-trafficcontroller.Similarly,noisedidnotaffectasubject’sabilitytotrackamovinglinewithasteeringwheel,butitdidaffectthesubject’sabilitytorepeatnumberswhiletracking(FinkelmandGlass1970).

　　Probablythemostsignificantfindingfromtheresearchonnoiseisthatitspredictabilityismoreimportantthanhowlouditis.Wearemuchmoreableto“tuneout”long-lasingbackgroundnoise,evenifitisquiteloud,thantoworkundercircumstanceswithunexpecteddisturbanceofnoise.InGlassandSinger’sstudy,inwhichsubjectswereexposedtoburstsofnoiseastheyworkedonatask,somesubjectsheardloudburstsandothersheardsoftbursts.Forsomesubjects,theburstswerespacedexactlyoneminuteapart(predictablenoise);othersheardthesomeamountofnoiseoverall,buttheburstsoccurredatrandomintervals(unpredictablenoise).Subjectsreportedfindingthepredictableandunpredictablenoiseequallyannoying,andallsubjectsperformedataboutthesamelevelduringthenoiseportionoftheexperiment.Butthedifferentnoiseconditionshadquitedifferentafter-effectswhenthesubjectswererequiredtoproofreadwrittenmaterialunderconditionsofn