简介：Manypatientswithsensorineuralhearinglosshaveaprecipitoushigh-frequencylosswithrelativelygoodthresholdsinthelowfrequencies.Thispresentpaperbrieflyintroducesandcomparesthebasicprinciplesoffourtypesoffrequencyloweringalgorithmswithemphasisonnonlinearfrequencycompression(NLFC).AreviewoftheeffectsoftheNLFCalgorithmonspeechandmusicperceptionandsoundqualityappraisalisthenprovided.Forvowelperception,itseemsthatthebenefitsprovidedbyNLFCarelimited,whichareprobablyrelatedtotheparametersettingsofthecompression.Forconsonantperception,severalstudieshaveshownthatNLFCprovidesimprovedperceptionofhighfrequencyconsonantssuchas/s/and/z/.However,afewotherstudieshavedemonstratednegativeresultsinconsonantperception.Intermsofsentencerecognition,persistentuseofNLFCmightprovideimprovedperformance.Comparedtotheconventionalprocessing,NLFCdoesnotalterthespeechsoundqualityappraisalandmusicperceptionaslongasthecompressionsettingisnottooaggressive.Inthesubsequentsection,therelevantfactorswithregardtoNLFCsettings,time-courseofacclimatization,listenercharacteristics,andperceptualtasksarediscussed.AlthoughtheliteratureshowsmixedresultsontheperceptualefficacyofNLFC,thistechniqueimprovedcertainaspectsofspeechunderstandingincertainhearing-impairedlisteners.LittleresearchisavailableonspeechperceptionoutcomesinlanguagesotherthanEnglish.MoreclinicaldataareneededtoverifytheperceptualefficacyofNLFCinpatientswithprecipitoushigh-frequencyhearingloss.Suchknowledgewillhelpguideclinicalrehabilitationofthosepatients.