Frequency of greatest temporary hearing threshold shift in harbor seals (Phoca vitulina) depends on fatiguing sound level

TitleFrequency of greatest temporary hearing threshold shift in harbor seals (Phoca vitulina) depends on fatiguing sound level
Publication TypeJournal Article
Year of Publication2019
AuthorsKastelein, Ronald A., Helder-Hoek Lean, and Gransier Robin
JournalThe Journal of the Acoustical Society of America
Volume145
Pagination1353-1362
ISBN Number0001-4966
EndNote Rec Number12562
Abstract

Harbor seals may suffer hearing loss due to intense sounds. After exposure for 60?min to a continuous 6.5?kHz tone at sound pressure levels of 123?159 dB re 1 µPa, resulting in sound exposure levels (SELs) of 159?195?dB re 1??Pa2s, temporary threshold shifts (TTSs) in two harbor seals were quantified at the center frequency of the fatiguing sound (6.5?kHz) and at 0.5 and 1.0 octaves above that frequency (9.2 and 13.0?kHz) by means of a psychoacoustic technique. Taking into account the different timing of post-exposure hearing tests, susceptibility to TTS was similar in both animals. The higher the SEL, the higher the TTS induced at frequencies above the fatiguing sound's center frequency. Below ?179 dB re 1??Pa2s, the maximum TTS was at the center frequency (6.5 kHz); above ?179?dB re 1??Pa2s, the maximum TTS was at half an octave above the center frequency (9.2 kHz). These results should be considered when interpreting previous TTS studies, and when estimating ecological impacts of anthropogenic sound on the hearing and ecology of harbor seals. Based on the results of the present study and previous studies, harbor seal hearing, in the frequency range 2.5?6.5?kHz, appears to be approximately equally susceptible to TTS.