Print Email Facebook Twitter Underwater hearing sensitivity of a male and a female Steller sea lion (Eumetopias jubatus) Title Underwater hearing sensitivity of a male and a female Steller sea lion (Eumetopias jubatus) Author Kastelein, R.A. van Schie, R. Verboom, W.C. de Haan, D. TNO Defensie en Veiligheid Publication year 2005 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. © 2005 Acoustical Society of America. Subject MarineAuditionFrequency modulationSensitivity analysisAcoustic signalsAudiogramsDetection thresholdsUnderwater acousticsAcousticsAnimal experimentAudiographyAuditory thresholdEumetopias jubatusHearing acuityMarine mammalSealVocalizationAuditory ThresholdHearingSea lions To reference this document use: http://resolver.tudelft.nl/uuid:885c9ed4-8753-45ce-8615-07ac7e027c56 DOI https://doi.org/10.1121/1.1992650 TNO identifier 238669 Source Journal of the Acoustical Society of America, 118 (3), 1820-1829 Document type article Files To receive the publication files, please send an e-mail request to TNO Library.