"Say-stay" identification and psychoacoustic performance of hearing-impaired listeners

Controversy exists over the extent to which psychoacoustic abilities explain speech perception. The present study addressed this issue by assessing the contribution of psychoacoustic abilities to speech identification by hearing-impaired listeners. Speech stimuli and nonspeech analogs were presented to normal-hearing and hearing-impaired listeners with varying degrees of hearing loss. Phonemic judgments for synthetic versions of "say-stay" stimuli were evaluated as a function of first formant onset frequency and of silence duration between the /s/ noise and the vocalic portion. Three psychoacoustic measures were obtained: glide onset frequency discrimination, gap detection in noise, and gap detection in speechlike composite signals. Although the resulting difference limens increased with increasing hearing loss, the acoustic cues to the speech contrast were available to all listeners. Nonetheless, the response patterns to the speech stimuli varied among groups in a manner that was not explained by the psychoacoustic results. Thus, although hearing-impaired listeners were able to detect and discriminate essential acoustic cues for speech, the perceptual organization of speech stimuli appeared to differ with degree of loss. Alternative explanations for the findings are considered, including the possible effect of hearing loss on auditory/linguistic experience.