Effects of stimulus repetition rate and frequency on the auditory brainstem response in normal cochlear-impaired, and VIII nerve/brainstem-impaired subjects.

The effects of signal repetition rate and frequency on the auditory brainstem responses of normal listeners, of persons with cochlear lesions, and of persons with VIII nerve/brainstem lesions were evaluated. The normal group exhibited more waves I and II than did the cochlear and VIII/brainstem groups. The normal and cochlear groups exhibited more waves III and V than did the VIII nerve/brainstem group. The latency of wave I was not different among groups, whereas wave V was significantly later in the VIII nerve/brainstem group than in the other groups. Waves I, III, and V were later for 50/s than for 10/s. Waves I and III displayed shorter latencies for 4000 Hz than for 2000 Hz, whereas wave V displayed similar latencies for the two stimuli. In conclusion, cochlear pathology (less than or equal to 65 dB HL) does not prolong the latencies of waves I and V. A dual mechanism is discussed to explain the rate-dependent latency shift of wave V.