Effects of signal-to-noise ratio on the auditory brainstem response to 0.5 and 2 kHz tone bursts in broadband noise and highpass noise or notch noise.

This study investigated the effects of signal-to-noise ratio (S/N) on the latency and amplitude of th3 auditory brainstem response (Wave V) using 0.5 and 2 kHz tone bursts in highpass/notch noise and broadband noise. Normal listeners were presented with 40 and 80 dB nHL tone bursts in quiet and in noise at S/Ns of 10, 15, 20, and 25 dB. The latency data suggest that, at moderate and high intensities, highpass/notch noise or broadband noise is preferred to the quiet condition because of the improved frequency specificity provided by the masking. Highpass/notch noise appears preferable to broadband noise when testing at moderate to high levels because the former produced larger Wave V amplitudes to 0.5 and 2 kHz tone bursts at 80 dB nHL. The 80 dB nHL data also suggest that S/Ns of 15-25 dB should be selected when the highpass/notch noise is mixed with moderate to high level 0.5 and 2 kHz tone bursts. In contrast to the 80 dB nHL data, Wave V amplitudes to the 40 dB nHL tone bursts suggest that testing in quiet may be preferred to testing in noise when 0.5 and 2 kHz tone bursts are presented at low levels. This is because of the simplicity of instrumentation and because larger amplitudes were observed in quiet than in noise.