Anatomical predictions of hearing in the North Atlantic Right Whale

TitleAnatomical predictions of hearing in the North Atlantic Right Whale
Publication TypeJournal Article
Year of Publication2007
AuthorsParks, S. E., D. R. Ketten, J. A. Trehey, J. T. O' Malley, and J. J. Arruda
JournalThe Anatomical Record
Start Page734
Date Published05/2007
Type of ArticleScientific
Keywordsacoustics, audition, computerized tomography, ct scan, ear, eubalaena glacialis, ganglion cell density, hearing, hearing range, hearing sensitivity, inner ear, marine mammals, model, morphology, morphometrics, mysticetes, north atlantic right whale, sound reception, spiral ganglion cell count

Some knowledge of the hearing abilities of right whales is important for understanding their acoustic communication system and possible impacts of anthropogenic noise. Traditional behavioral or physiological techniques to test hearing are not feasible with right whales. Previous research on the hearing of marine mammals has shown that functional models are reliable estimators of hearing sensitivity in marine species. Fundamental to these models is a comprehensive analysis of inner ear anatomy. Morphometric analyses of 18 inner ears from 13 stranded North Atlantic right whales (Eubalaena glacialis) were used for development of a preliminary model of the frequency range of hearing. Computerized tomography was used to create two-dimensional (2D) and 3D images of the cochlea. Four ears were decalcified and sectioned for histologic measurements of the basilar membrane. Basilar membrane length averaged 55.7 mm (range, 50.5 mm–61.7 mm). The ganglion cell density/mm averaged 1,842 ganglion cells/mm. The thickness/width measurements of the basilar membrane from slides resulted in an estimated hearing range of 10 Hz–22 kHz based on established marine mammal models. Additional measurements from more specimens will be necessary to develop a more robust model of the right whale hearing range.