Auditory masking by ambient noise in black rockfish Sebastes schlegeli

Abstract

Auditory masking was determined for the black rockfish by using white noise as masking stimuli with spectrum levels of around 70, 80 and 90 dB re 1 μPa/Hz1/2. The auditory thresholds at four frequencies from 100 to 500 Hz varied with background noise, and increased from 10 to 24 dB at the highest noise level as compared with thresholds in a quiet condition for each frequency. Values for the critical ratio, calculated in terms of the masked thresholds in relation to masking noise spectrum level, ranged from 27 dB at 100 Hz to 40 dB at 500 Hz. The noise spectrum levels that start masking are estimated to be 66-77 dB at the test frequencies suggesting that background noise larger than those values affects hearing in the black rockfish. The thresholds are 27-40 dB higher than the spectrum level of the noise.