Low-Frequency Underwater Hearing Sensitivity in Belugas

Underwater audiograms are available for only a few odontocete cetacean species: Phocoena phocoena, Inia geoffrenis, Tursiops truncatus, Delphinapterus leucas, Orcinus orca, and Pseudorca crassidens. Only Johnson (1967) measured thresholds below 1kHz. Thresholds below 2kHz are difficult to measure accurately because testing is usually done in small, very shallow pools where problems with standing waves and interference are nearly insurmountable. Also, most underwater transducers cannot produce the high amplitudes needed with low enough distortion. To avoid this problem, we used airborne speakers to measure the underwater hearing sensitivity of three captive belugas during 1983. We report three low-frequency audiograms with new data at 125, 250, and 500 Hz and data at 1, 2, 4, and 8 kHz that agree with those measured for belugas by White et al. (1978).

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Frank T. Awbrey, Jeanette A. Thomas, and Ronald A. Kastelein. Published in the Journal of the Acoustical Society of America 84(6), December 1988.