Auditory brainstem response to tone bursts in quiet, notch noise, highpass noise, and broadband noise

This study investigated the effects of tone bursts (1000 Hz, 2000 Hz, and 4000 Hz) in quiet, notch noise, highpass noise, and broadband noise on the identifiability, latency, and amplitude of the auditory brainstem response (wave V). Normal listeners were presented with 40 dB and 80 dB nHL tone bursts having rise-plateau-fall times of 1 msec. Wave V was observed in all subjects at 40 dB and 80 dB nHL for the quiet and noise conditions. The latency findings suggest that responses elicited by the 80 dB nHL tone bursts in quiet were, in part, mediated by regions on the basilar membrane that did not correspond to the center frequency of the tone burst. To increase frequency-specificity, high-level tone bursts (e.g., 80 dB nHL) should be mixed with notch, highpass, or broadband noise. The use of noise conditions for low intensity levels (e.g., 40 dB nHL) does not appear necessary for isolating the response because both the notch and the highpass conditions yielded latencies similar to the quiet condition. Although similar wave V amplitudes were found at all frequencies, amplitudes were smaller for the broadband noise than for the quiet, notch, and highpass conditions. Thus, the latter conditions seem preferred.