Click-Evoked Potentials in a Large Marine Mammal, the Adult Male Northern Elephant Seal (Mirounga angustirostris) (L)

Auditory evoked potential (AEP) hearing studies in marine mammals should consider an expected size-dependent reduction in AEP amplitude. This study is the first to measure the click-evoked response in a large marine mammal, the adult male elephant seal (Mirounga angustirostris) . Click stimuli were presented at peak-peak equivalent sound pressure Ievels of 117-118 dB re: 20,uPa. Three positive peaks (PI-P3) and two negative peaks (N4 and N5) were observed in the AEP. Response latencies were longer than previously observed in a 1.8 yr old seal and the maximum peak-peak amplitude was comparatively reduced by more than 60%. The inverse relationship between size and AEP amplitude will likely require increased averaging with larger subjects and possibly modifications to electrode placement and design in order to increase the quality of recorded evoked responses.