title: Temporary shift in masked hearing thresholds in odontocetes after exposure to single underwater impulses from a seismic watergun.
abstract: A behavioral response paradigm was used to measure masked underwater hearing thresholds in a bottlenose dolphin (Tursiops truncatus) and a white whale (Delphinapterus leucas) before and after exposure to single underwater impulsive sounds produced from a seismic watergun. Pre- and postexposure thresholds were compared to determine if a temporary shift in masked hearing thresholds (MTTS), defined as a 6-dB or larger increase in postexposure thresholds, occurred. Hearing thresholds were measured at 0.4, 4, and 30 kHz. MTTSs of 7 and 6 dB were observed in the white whale at 0.4 and 30 kHz, respectively, approximately 2 min following exposure to single impulses with peak pressures of 160 kPa, peak-to-peak pressures of 226 dB re 1 microPa, and total energy fluxes of 186 dB re 1 microPa2 x s. Thresholds returned to within 2 dB of the preexposure value approximately 4 min after exposure. No MTTS was observed in the dolphin at the highest exposure conditions: 207 kPa peak pressure, 228 dB re 1 microPa peak-to-peak pressure, and 188 dB re 1 microPa2 x s total energy flux.
authors.affiliation: Space and Naval Warfare Systems Center, San Diego, California 92152-5000, USA.
authors.forename: James J
authors.initials: JJ
authors.lastname: Finneran
authors.forename: Carolyn E
authors.initials: CE
authors.lastname: Schlundt
authors.forename: Randall
authors.initials: R
authors.lastname: Dear
authors.forename: Donald A
authors.initials: DA
authors.lastname: Carder
authors.forename: Sam H
authors.initials: SH
authors.lastname: Ridgway
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D001305:Auditory Fatigue; D001309:Auditory Threshold; D004289:Dolphins / Q000523:psychology*; D008144:Loudness Perception; D010470:Perceptual Masking; D010897:Pitch Discrimination; D013018:Sound Spectrography; D014907:Whales / Q000523:psychology*