Temporal characteristics of the acoustic reflex

Temporal aspects of the acoustic reflex response were estimated for normally hearing subjects, subjects with noise-induced hearing loss and children with sensorineural hearing impairment. Onset latency and rise/fall times of admittance change were measured from the averaged responses (8 presentations) to tone bursts of 250 ms durations and 10 ms rise/fall time. Tone burst frequency was varied from 500 to 4000 Hz. No differences between groups were observed for onset responses. Compared to the data from normally hearing subjects, the offset responses were slightly longer for subjects with noise-induced hearing loss and were considerably longer for hearing-impaired children. Due to the prolongation seen for noise-exposed subjects, it is difficult to interpret these data in terms of site of lesion. Still, the differences between hearing-impaired children and normal subjects suggest that acoustic reflex offset latency may be a useful screening device.