Auditory brainstem response to clicks in quiet, notch noise, and highpass noise

Auditory brainstem responses to clicks in quiet, notch noise, and highpass noise were recorded from 10 normal-hearing adults. Contrary to some reports, the latency of wave V increased as the center frequency of the notch decreased. Response identifiability and wave V amplitudes were similar for the notch and highpass noises. Thus, the additional frequencies below the notch did not contribute sufficiently to the response to alter identifiability or amplitude. Notch noise, as compared to the highpass noise, is advantageous because of the increased frequency-specificity provided by the low-frequency masking noise. Presenting clicks in highpass or notch noise centered at 500 Hz is of limited value for assessing auditory sensitivity. This is because the range of testable hearing levels is restricted by (1) a high normal ABR threshold (approximately 65 dB nHL) and (2) the high noise levels required to mask the click. This limited dynamic range for assessing hearing loss is a major limitation of click in noise testing, particularly for 500 Hz. Generating a two-point audiogram by presenting clicks in noise with notches centered around 1000 Hz and 4000 Hz may prove promising for assessing auditory sensitivity.