ASA 126th Meeting Denver 1993 October 4-8

3aPP6. Modulation detection interference in subjects with a mild, high-frequency hearing loss.

Jane M. Opie Sid P. Bacon

Psychoacoust. Lab., Dept. of Speech and Hear. Sci., Arizona State Univ., Tempe, AZ 85287-1908

Modulation detection interference (MDI) was measured in three normal-hearing subjects and in three subjects with mild, high-frequency sensorineural hearing impairment. Subjects detected 10-Hz amplitude modulation of a signal carrier in quiet and in the presence of a masker carrier that was unmodulated or amplitude modulated (depth of 100%) from 2 to 40 Hz. The carrier frequencies were 984 and 3952 Hz; either could serve as the masker, while the other served as the signal. Thus, for the hearing-impaired subjects, one carrier was in the region of hearing loss. In experiment 1, both the signal and masker were presented at equal sound pressure levels (SPLs). In experiment 2, the effect of sensation level (SL) was considered. In both experiments, there was generally little difference between the two groups when the signal carrier was in a region of normal hearing. However, the hearing-impaired subjects demonstrated more MDI than did the normal-hearing subjects when the signal was presented within the region of hearing loss. This suggests that even mildly hearing-impaired subjects may have difficulty processing complex, time-varying stimuli. Further, it appears that this may not be solely attributable to audibility but may be mediated by other factors. [Work supported by NIDCD.]