Relationship between auditory evoked potential (AEP) and behavioral audiograms in odontocete cetaceans Free

Auditory evoked potentials (AEPs) offer an alternative to behavioral methods of determining auditory sensitivity in marine mammals. The technique can be performed without the need for animal training, substantially expediting the process, and has the potential for application to stranded and rehabilitating marine mammals, thus providing an opportunity to determine hearing sensitivity in animals not likely to be kept in captivity. As an emerging technology in the field of marine mammalogy, the equivalence of AEP and behavioral thresholds remains to be quantitatively assessed. Human and laboratory animal AEPs are typically −5 to +20 dB of behaviorally determined thresholds and vary by technique and frequency tested. To be an effective tool in the field of marine mammalogy, the expected variation in AEP thresholds relative to behavioral thresholds in marine mammal species needs to be determined. We compare the behavioral and AEP audiograms of several odontocetes covering a range of normal hearing to profound hearing loss and demonstrate the offsets between results obtained with the two methods. Thresholds determined by the two methods show generally good agreement and demonstrate the utility of AEPs as an emerging technology in the study of marine mammal audiometry.