LONG-TERM GOALS

Pinnipeds (seals, sea lions, and walruses) are amphibious marine mammals that are susceptible to coastal anthropogenic noise. The long-term goals of this effort are to improve understanding of (1) the sound detection capabilities of several pinniped species, and (2) the effects of noise exposure on the sound detection capabilities of these species. The research will show how amphibious mammals receive and perceive acoustic information in background noise. OBJECTIVES Improve understanding of hearing in pinnipeds by extending psychoacoustic profiles of sound reception obtained from simplified auditory processing tasks to those describing performance under increasingly complex acoustic conditions. Relate laboratory measurements to concurrent field studies of communication in fluctuating natural noise backgrounds. Strengthen predictive models that describe how signal structure and noise environments interact to constrain auditory performance, and develop weighting functions that can be used for species-typical acoustic risk assessments. APPROACH Psychoacoustic measurements of hearing are obtained from California sea lions, harbor seals, and northern elephant seals under highly controlled laboratory conditions. Long-term captive subjects ar