Reliability of underwater hearing thresholds in pinnipeds

Repeated measures of low-frequency underwater hearing sensi- tivity in individuals of three pinniped species tested over 4-7 years are pre- sented. Despite changes in the experience of the subjects and certain testing parameters (e.g., equipment and research personnel), measured underwater hearing thresholds within subjects over relatively long periods of time were quite similar at the frequencies tested (0.2-6.4 kHz). These data address the reliability of acoustic signal detection measurements over time in pinnipeds using psychophysical techniques. They are also relevant in considering the cumulative effects of aging, experience, and noise exposure on pinniped hear- ing in certain frequency bands.