Marine mammal ears: an anatomical perspective on underwater hearing

TitleMarine mammal ears: an anatomical perspective on underwater hearing
Publication TypeJournal Article
Year of Publication1998
AuthorsKetten, D. R.
JournalInternational Congress on Acoustics
Call NumberDRK6795
KeywordsABR, AEP, audiometry, auditory brainstem response, auditory evoked potentials, carnivora, cochlea, computerized tomography, ct scan, dolphins, FEM modeling, fissipedia, hearing, magnetic resonance imaging, mammalian ears, manatees, marine mammal ears, marine mammals, morphology, MRI, mysticetes, odobenids, odontocetes, otariids, phocids, pinnipeds, seals, sirenia

Recently, concerns over anthropogenic sounds in the oceans pushed us to develop a broader knowledge of marine mammal hearing. Methods ranging from conventional audiometry to FEM modeling have been employed. The resulting data suggest marine mammal ears are more diverse and complex than previously expected, with acoustic capabilities spanning infra to ultrasonic ranges. Seals are amphibious hearers but divide into air vs aquatic adapted ears. Whales have strikingly different ears adapted exclusively to hearing underwater and have specialized tissue paths to the ear, consistent with the acoustic impedance in water. Exceptional auditory nerve densities are found in all whales, and is not exclusively found in ultrasonic echolocators.