The influence of cochlear shape on low-frequency hearing

TitleThe influence of cochlear shape on low-frequency hearing
Publication TypeJournal Article
Year of Publication2008
AuthorsManoussaki, D., R. S. Chadwick, D. R. Ketten, J. J. Arruda, E. K. Dimitriadis, and J. T. O' Malley
JournalProceedings of the National Academy of Sciences
Start Page6162
Date Published02/2008
Type of ArticleScientific
Keywordscochlea, cochlear spiral, function, inner ear, low frequency hearing, mammalian evolution, spiral

The conventional theory about the snail shell shape of the mammalian cochlea is that it evolved essentially and perhaps solely to conserve space inside the skull. Recently, a theory proposed that the spiral‘s graded curvature enhances the cochlea’s mechanical response to low frequencies. This article provides a multi-species analysis of cochlear shape to test this theory and demonstrates that the ratio of the radii of curvature from the outermost and innermost turns of the cochlear spiral is a significant cochlear feature that correlates strongly with low-frequency hearing limits. The ratio, which is a measure of curvature gradient, is a reflection of the ability of cochlear curvature to focus acoustic energy at the outer wall of the cochlear canal as the wave propagates toward the apex of the cochlea.