Perception of rapid spectral change in speech by listeners with mild and moderate sensorineural hearing loss.

An experimental method is described for assessing the effect of sensorineural hearing impairment on the perception of particular speech cues. Stimuli consisted of synthetic consonant-vowel syllables, varying along a continuum in the duration of initial formant transitions, such that the shorter stimuli sounded like [bepsilon], and the longer ones sounded like [Wepsilon]. Subjects with mild and moderate hearing losses were asked to identify the stimuli, and their performance was compared to that of normal-hearing listeners. Observed differences suggest that categorizing these sounds as stops versus glides is especially difficult for some impaired listeners. This difficulty is shown to be specific to the "rapid spectral change" cue, independent of frequency content or intensity level. The importance of this finding with respect to categorical perception and the implications for further tests of impairment for speech are discussed briefly.