Abstract
Conditioning techniques were developed demonstrating that pure tone frequencies under water can exert nearly perfect control over the underwater click vocalizations of the California sea lion (Zalophus californianus). Conditioned vocalizations proved to be a reliable way of obtaining underwater sound detection thresholds in Zalophus at 13 different frequencies, covering a frequency range of 250 to 64,000 Hz. The audiogram generated by these threshold measurements suggests that under water, the range of maximal sensitivity for Zalophus lies between one and 28 kHz with best sensitivity at 16 kHz. Between 28 and 36 kHz there is a loss in sensitivity of 60 dB/octave. However, with relatively intense acoustic signals (> 38 dB re 1 μb underwater), Zalophus will respond to frequencies at least as high as 192 kHz. These results are compared with the underwater hearing of other marine mammals.
Full text
PDF
Images in this article
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Corso J. F., Levine M. Pitch-discrimination at high frequencies by air- and bone-conduction. Am J Psychol. 1965 Dec;78(4):557–566. [PubMed] [Google Scholar]
- Gourevitch G., Hack M. H. Audibility in the rat. J Comp Physiol Psychol. 1966 Oct;62(2):289–291. doi: 10.1037/h0023669. [DOI] [PubMed] [Google Scholar]
- Masterton B., Heffner H., Ravizza R. The evolution of human hearing. J Acoust Soc Am. 1969 Apr;45(4):966–985. doi: 10.1121/1.1911574. [DOI] [PubMed] [Google Scholar]
- Schusterman R. J., Balliet R. F. Conditioned vocalizations as a technique for determining visual acuity thresholds in sea lions. Science. 1970 Jul 31;169(3944):498–501. doi: 10.1126/science.169.3944.498. [DOI] [PubMed] [Google Scholar]
- Terhune J. M., Ronald K. The harp seal, Pagophilus groenlandicus (Erxleben, 1777). X. The air audiogram. Can J Zool. 1971 Mar;49(3):385–390. doi: 10.1139/z71-057. [DOI] [PubMed] [Google Scholar]