The influence of cochlear shape on low-frequency hearing
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.
- Publication:
-
Proceedings of the National Academy of Science
- Pub Date:
- April 2008
- DOI:
- 10.1073/pnas.0710037105
- Bibcode:
- 2008PNAS..105.6162M
- Keywords:
-
- inner ear;
- function;
- mammalian evolution;
- spiral;
- Physical Sciences:Applied Mathematics, Biological Sciences:Neuroscience