Underwater temporary threshold shift induced by octave-band noise in three species of pinniped

David Kastak, Ronald J. Schusterman, Brandon L. Southall, Colleen J. Reichmuth
1999 Journal of the Acoustical Society of America  
Pure-tone sound detection thresholds were obtained in water for one harbor seal ͑Phoca vitulina͒, two California sea lions ͑Zalophus californianus͒, and one northern elephant seal ͑Mirounga angustirostris͒ before and immediately following exposure to octave-band noise. Additional thresholds were obtained following a 24-h recovery period. Test frequencies ranged from 100 Hz to 2000 Hz and octave-band exposure levels were approximately 60-75 dB SL ͑sensation level at center frequency͒. Each
more » ... quency͒. Each subject was trained to dive into a noise field and remain stationed underwater during a noise-exposure period that lasted a total of 20-22 min. Following exposure, three of the subjects showed threshold shifts averaging 4.8 dB ͑Phoca͒, 4.9 dB ͑Zalophus͒, and 4.6 dB ͑Mirounga͒. Recovery to baseline threshold levels was observed in test sessions conducted within 24 h of noise exposure. Control sessions in which the subjects completed a simulated noise exposure produced shifts that were significantly smaller than those observed following noise exposure. These results indicate that noise of moderate intensity and duration is sufficient to induce TTS under water in these pinniped species.
doi:10.1121/1.427122 pmid:10462817 fatcat:uwjhw63wvbdpzi6cnyd4qlwzg4