title: Temporary threshold shifts and recovery in a harbor porpoise (Phocoena phocoena) after octave-band noise at 4 kHz.
abstract: 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 μPa(2) s. 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 μPa(2) s) which caused a significant TTS(1-4) was due to exposure to an SPL of 124 dB re 1 μPa for 7.5 min. The maximum TTS(1-4), induced after a 240 min exposure to 148 dB re 1 μPa, was around 15 dB at a SEL of 190 dB re 1 μPa(2) s. Recovery time following TTS varied between 4 min and under 96 min, depending on the exposure level, duration, and the TTS induced.
authors.affiliation: Sea Mammal Research Company (SEAMARCO), Julianalaan 46, 3843 CC Harderwijk, The Netherlands. researchteam@zonnet.nl
authors.forename: Ronald A
authors.initials: RA
authors.lastname: Kastelein
authors.forename: Robin
authors.initials: R
authors.lastname: Gransier
authors.forename: Lean
authors.initials: L
authors.lastname: Hoek
authors.forename: Juul
authors.initials: J
authors.lastname: Olthuis
mesh_terms: D000818:Animals; D001299:Audiometry; D001305:Auditory Fatigue; D008297:Male; D009622:Noise / Q000009:adverse effects*; D050741:Phocoena / Q000502:physiology*; D011312:Pressure; D011571:Psychoacoustics; D020127:Recovery of Function; D013018:Sound Spectrography; D013550:Swimming; D013997:Time Factors