The influence of cochlear shape on low-frequency hearing
Publication Type: |
Journal Article |
Year of Publication: |
2008 |
Authors: |
D. Manoussaki, R. S. Chadwick, D. R. Ketten, J. Arruda, E. K. Dimitriadis, J. T. O'Malley |
Publication/Journal: |
Proceedings of the National Academy of Sciences |
Keywords: |
function, inner ear, mammalian evolution, spiral |
ISBN: |
0027-8424 1091-6490 |
Abstract:
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 multispecies 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.