Peer Reviewed Publication
Journal of the Acoustical Society of America
Kastelein, R.A., Gransier, R., Hoek, L. and Olthuis, J.
Safety criteria for underwater sound produced during offshore pile driving are needed to protect marine mammals. A harbor porpoise was exposed to fatiguing noise at 18 sound pressure level (SPL) and duration combinations. Its temporary hearing threshold shift (TTS) and hearing recovery were quantified with a psychoacoustic technique. Octave-band white noise centered at 4 kHz was the fatiguing stimulus at three mean received SPLs (124, 136, and 148 dB re 1 μPa) and at six durations (7.5, 15, 30, 60, 120, and 240 min). Approximate received sound exposure levels (SELs) varied between 151 and 190 dB re 1 μPa2s. Hearing thresholds were determined for a narrow-band frequency-swept sine wave (3.9–4.1 kHz; 1 s) before exposure to the fatiguing noise, and at 1–4, 4–8, 8–12, 48, and 96 min after exposure. The lowest SEL (151 dB re 1 μPa2s) which caused a significant TTS1–4 was due to exposure to an SPL of 124 dB re 1 μPa for 7.5 min. The maximum TTS1–4, induced after a 240 min exposure to 148 dB re 1 μPa, was around 15 dB at a SEL of 190 dB re 1 μPa2s. Recovery time following TTS varied between 4 min and under 96 min, depending on the exposure level, duration, and the TTS induced.
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