Perception of stress contrasts by the hearing impaired

Waveform manipulation and LPC resynthesis techniques were used to develop test stimuli in which the F0, amplitude, and durational cues for first versus second syllable stress were systematically and independently controlled. Both normal and exaggerated stress contrasts were represented in the test corpus. Twenty severely to profoundly hearing-impaired students served as subjects for a perceptual experiment and were asked to indicate whether the stress was on the first or second syllable of each two-syllable test item (data were also collected on a group of normal hearing controls). Results revealed that the hearing-impaired listeners were able to correctly identify the stressed syllable only for stimuli in which the amplitude cue was available. That is, they scored below chance on stimuli in which the durational and/or F0 cues were present but where the amplitude cue had been neutralized. Exaggerating the amplitude cue for stress resulted in higher identification scores. Exaggerating F0 and/or durational cues did not improve performance. The implications of these results will be discussed. [Work supported by PHS grant No. NS17764-05 to the Graduate Center, C.U.N.Y.]