Underwater hearing sensitivity of harbor seals (Phoca vitulina) for narrow noise bands between 0.2 and 80 kHz

• Published in: The Journal of the Acoustical Society of America
• Main Authors: Kastelein, Ronald A., Wensveen, Paul, Hoek, Lean, Terhune, John M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2009
• Subjects: Phoca vitulina
• Online Access: https://risweb.st-andrews.ac.uk/portal/en/researchoutput/underwater-hearing-sensitivity-of-harbor-seals-phoca-vitulina-for-narrow-noise-bands-between-02-and-80-khz(f40d3225-45ff-4a5e-9d3e-07ae3948da65).html; https://doi.org/10.1121/1.3132522; http://www.scopus.com/inward/record.url?scp=68149105771&partnerID=8YFLogxK

The underwater hearing sensitivities of two 1.5-year-old female harbor seals were quantified in a quiet pool built specifically for acoustic research, by using a behavioral psychoacoustic technique. The animals were trained to respond when they detected an acoustic signal and not to respond when they did not ("go/no-go" response). Fourteen narrowband noise signals (1/3-octave bands but with some energy in adjacent bands), at 1/3-octave center frequencies of 0.2-80 kHz, and of 900 ms duration, were tested. Thresholds at each frequency were measured using the up-down staircase method and defined as the stimulus level resulting in a 50% detection rate. Between 0.5 and 40 kHz, the thresholds corresponded to a 1/3-octave band noise level of ∼60 dB re 1 μPa (SD±3.0 dB). At lower frequencies, the thresholds increased to 66 dB re 1 μPa and at 80 kHz the thresholds rose to 114 dB re 1 μPa. The 1/3-octave noise band thresholds of the two seals did not differ from each other, or from the narrowband frequency-modulated tone thresholds at the same frequencies obtained a few months before for the same animals. These hearing threshold values can be used to calculate detection ranges of underwater calls and anthropogenic noises by harbor seals.