Underwater hearing sensivity of a male and female Steller sea lion (Eumetopias jubatus)

R.A. Kastelein, R. van Schie, W.C. Verboom, D. de Haan

    Research output: Contribution to journalArticleAcademicpeer-review

    14 Citations (Scopus)

    Abstract

    The unmasked underwater hearing sensitivities of an 8-year-old male and a 7-year-old female Steller sea lion were measured in a pool, by using behavioral psychophysics. The animals were trained with positive reinforcement to respond when they detected an acoustic signal and not to respond when they did not. The signals were narrow-band, frequency-modulated stimuli with a duration of 600 ms and center frequencies ranging from 0.5 to 32 kHz for the male and from 4 to 32 kHz for the female. Detection thresholds at each frequency were measured by varying signal amplitude according to the up¿down staircase method. The resulting underwater audiogram (50% detection thresholds) for the male Steller sea lion showed the typical mammalian U-shape. His maximum sensitivity (77 dB re: 1 µPa, rms) occurred at 1 kHz. The range of best hearing (10 dB from the maximum sensitivity) was from 1 to 16 kHz (4 octaves). Higher hearing thresholds (indicating poorer sensitivity) were observed below 1 kHz and above 16 kHz. The maximum sensitivity of the female (73 dB re: 1 µPa, rms) occurred at 25 kHz. Higher hearing thresholds (indicating poorer sensitivity) were observed for signals below 16 kHz and above 25 kHz. At frequencies for which both subjects were tested, hearing thresholds of the male were significantly higher than those of the female. The hearing sensitivity differences between the male and female Steller sea lion in this study may be due to individual differences in sensitivity between the subjects or due to sexual dimorphism in hearing
    Original languageEnglish
    Pages (from-to)1820-1829
    JournalJournal of the Acoustical Society of America
    Volume118
    Issue number3, Pt. 1
    DOIs
    Publication statusPublished - 2005

    Keywords

    • harbor seal
    • zalophus-californianus
    • auditory-sensitivity
    • callorhinus-ursinus
    • critical ratios
    • killer whales
    • tone pulses
    • 3 pinnipeds
    • frequency
    • audiogram

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