A theory of speech perception in normal and hearing-impaired ears

Speech perception;psychoacoustings;hearing aid fitting;cochlear dead regions;consonant confusion

Singh, Riya O. ; Allen ; Jont B.

关键词: Speech perception;    psychoacoustings;    hearing aid fitting;    cochlear dead regions;    consonant confusion;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/18447/Singh_Riya.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

This research investigates the longstanding problem of understanding humanspeech perception. We aim to study speech perception and decode perceptualcues in speech by conducting psychoacoustic experiments on several subjectsby presenting them with nonsense consonant-vowel (CV) syllables in various kinds of masking noise at di fferent signal-to-noise ratios (SNRs). Ourresearch with a large number of normal hearing (NH) listeners shows thatNH speech perception is deterministic and the error is essentially zero whenthe main perceptual feature (or event) of the utterance is audible. With theperceptual CV cues precisely known, one can predict how an average normal hearing (ANH) listener would behave in a certain type and degree ofmasking noise. The next major goal of the current research is to characterize hearing-impaired (HI) ears by using our knowledge of specific consonantspeech cues in ANH ears, thus quantifying how the HI ears di ffer from ANH ears in their use of acoustic cues. Our analysis shows that HI ears may havepoor temporal and/or frequency resolution, because of which they are unable to hear only a few consonants, yet they can hear the rest. We argue that itis necessary to measure this consonant dependence in order to design a more sensitive hearing aid fi tting technique, and no other clinical measure used currently (audiometry, average speech recognition scores, speech in noise tests) is useful in characterizing speech-loss, in HI ears. We measured 46 HI earswith our CV discrimination test using the current hearing aid amplifi cation technique NAL-R; the results show that though NAL-R improves the aver-age score, it degrades a few consonants under certain circumstances. Thisresearch also addresses the important issue of cochlear dead regions, whichare places along the basilar membrane of the cochlea where the inner haircells are degenerate. We propose a new method to diagnose dead regionsbased on comodulation masking release. This project extends our effort toachieve a fundamental insight into the nature of both ANH and HI speechperception, enabling the design of hearing aids that are functionally usefulin high ambient noise and that help make audible the sounds that the HI earcould not hear previously, without aff ecting the sounds that they can hear.