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Volume 118, Issue 5, November 2005
- PHYSIOLOGICAL ACOUSTICS 
118(2005); http://dx.doi.org/10.1121/1.2047128View Description Hide Description
Behavioral psychophysical techniques were used to evaluate the residual effects of underwater noise on the hearing sensitivity of three pinnipeds: a California sea lion (Zalophus californianus), a harbor seal (Phoca vitulina), and a northern elephant seal (Mirounga angustirostris). Temporary threshold shift (TTS), defined as the difference between auditory thresholds obtained before and after noise exposure, was assessed. The subjects were exposed to octave-band noise centered at at two sound pressure levels: 80 and SL (re: auditory threshold at ). Noise exposure durations were 22, 25, and . Threshold shifts were assessed at 2500 and . Mean threshold shifts ranged from . Full recovery of auditory sensitivity occurred within of noise exposure. Control sequences, comprising sham noise exposures, did not result in significant mean threshold shifts for any subject. Threshold shift magnitudes increased with increasing noise sound exposure level (SEL) for two of the three subjects. The results underscore the importance of including sound exposure metrics (incorporating sound pressure level and exposure duration) in order to fully assess the effects of noise on marine mammal hearing.