Psychophysical and electrophysiological aerial audiograms of a Steller sea lion (Eumetopias jubatus).
A within-subject comparison of auditory steady-state response (ASSR) and psychophysical measurements of aerial hearing sensitivity was conducted with an individual of the largest otariid species, the Steller sea lion. Psychophysical methods were used to obtain an unmasked aerial audiogram at 13 frequencies, spanning a range of 0.125-34 kHz. The subject had a hearing range (frequencies audible at 60 dB(rms) re 20 microPa) of about 0.250-30 kHz, and a region of best hearing sensitivity from 5-14.1 kHz. The psychophysical aerial audiogram of this Steller sea lion was remarkably similar to aerial audiograms previously obtained for California sea lions and northern fur seals, suggesting that the otariid pinnipeds form a functional hearing group. ASSR thresholds, measured at frequencies of 1, 2, 5, 10, 20, and 32 kHz, were elevated relative to corresponding psychophysical thresholds, ranging from +1 dB at 20 kHz, to +31 dB at 1 kHz. The ASSR audiogram accurately predicted the subject's high-frequency cutoff, and provided a reasonable estimate of hearing sensitivity at frequencies above 2 kHz. In testing situations where psychophysical methods are not possible, ASSR methods may provide an objective and efficient estimate of behavioral hearing sensitivity in otariid pinnipeds.
Mulsow
Jason
J
Department of Ocean Sciences, Long Marine Laboratory, University of California, Santa Cruz, 100 Shaffer Road, Santa Cruz, CA 95060, USA. jason.mulsow@gmail.com
Reichmuth
Colleen
C
D000161:Acoustic Stimulation; D000818:Animals; D001301:Audiometry, Pure-Tone; D001307:Auditory Perception; D001309:Auditory Threshold; D001522:Behavior, Animal; D003463:Cues; D016057:Evoked Potentials, Auditory, Brain Stem; D008297:Male; D011571:Psychoacoustics; D015203:Reproducibility of Results; D046070:Sea Lions / Q000502:physiology* / Q000523:psychology*; D013018:Sound Spectrography; D013997:Time Factors