Sea Mammal Research Company (SEAMARCO), Julianalaan 46, 3843 CC Harderwijk, The Netherlands.
Department of Neurosciences, KU Leuven-University of Leuven, ExpORL, Herestraat 49, Box 721, 3000 Leuven, Belgium.
J Acoust Soc Am. 2019 Mar;145(3):1353. doi: 10.1121/1.5092608.
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 μPas, 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 μPas, the maximum TTS was at the center frequency (6.5 kHz); above ∼179 dB re 1 μPas, 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.
由于强烈的声音，港海豹可能会遭受听力损失。在 123-159 dB re 1 µPa 的连续 6.5 kHz 音调下暴露 60 分钟后，导致声暴露水平（SEL）为 159-195 dB re 1 μPas，通过心理声学技术在疲劳声（6.5 kHz）的中心频率和该频率上方的 0.5 和 1.0 个倍频程（9.2 和 13.0 kHz）量化了两只港海豹的暂时阈移（TTS）。考虑到暴露后听力测试的不同时间安排，两种动物对 TTS 的敏感性相似。SEL 越高，在疲劳声中心频率以上的频率上诱导的 TTS 越高。在约 179 dB re 1 μPas 以下，最大 TTS 出现在中心频率（6.5 kHz）；在约 179 dB re 1 μPas 以上，最大 TTS 出现在中心频率上方半倍频程（9.2 kHz）。在解释以前的 TTS 研究和估计人为声音对港海豹听力和生态的生态影响时，应考虑这些结果。基于本研究和以前研究的结果，港海豹在 2.5-6.5 kHz 的频率范围内的听力似乎对 TTS 具有大致相同的敏感性。
