Cochlear tuning may reflect tectorial membrane resonance

Abstract

Until recently it was not possible to account accurately for the basilar‐membrane amplitude and phase data of Rhode (1971). This may be so because the basilar membrane with its attachments was treated as a simple mechanical system consisting of stiffness, mass, and resistance distributed along the cochlea. When it is assumed instead that the mass of the tectorial membrane is attached elastically to the basilar membrane so that it can resonate in the radial mode at a frequency slightly above the measured best frequency, the resulting load on the basilar membrane leads to an amplitude and phase pattern in agreement with Rhode's. The effect was demonstrated on simple mechanical and network models. The latter yielded simultaneously a shear motion between the tectorial membrane and the reticular lamina, which paralleled neural tuning curves. The shear motion is generally regarded as the adequate stimulus for the hair cells. Construction of the tuning curves included a variable damping consistent with Rhode's r...