EFFECTS OF SIGNAL-TO-NOISE RATIO ON THE AUDITORY BRAIN-STEM RESPONSE TO TONE BURSTS IN NOTCH NOISE AND BROAD-BAND NOISE

This study investigated the effects of signal-to-noise ratio (S/N) on the latency and amplitude of the auditory brainstem response (Wave V) using 1 and 4 kHz tone bursts in notch noise and broadband noise. Normal listeners were presented with 40 dB and 80 dB nHL tone bursts in quiet and in noise at S/Ns of1O, 15, 20, and 25 dB. The latency data suggest that at low intensity levels tone bursts in quiet may be preferred to testing in noise. At moderate and high intensities, however, notch noise or broadband noise is preferred to the quiet condition because of the improved frequency specificity provided by the masking. When testing patients with hat or gradually sloping audiometric configurations at moderate to high intensities with 4 kHz, either notch noise or broadband noise with an S/N of 15 to 25 dB may be used. When presenting 1 kHz tone bursts at high intensities to patients having Bat and gradually sloping losses, a notch noise at S/Ns of 10 to 25 dB is preferred to broadband noise. The use of a notch noise at 10 dB S/N may be the stimulus of choice when testing patients with moderately to steeply sloping audiometric configurations with 1 or 4 kHz tone bursts.