Frequency ratios of SOAEs match the inter-cell spacing of outer hair cells: support for a SAW model of the cochlea

A new resonance theory of hearing models the cochlea as a surface acoustic wave (SAW) resonator. This SAW model calls for outer hair cells (OHCs) to respond piezoelectrically to intracochlear fluid pressure, and, via associated electomotility, to generate slowly propagating surface tension waves (ripples) on the undersurface of the overlying tectorial membrane. Because OHCs are combined sensors and effectors, the ripples continue to reverberate between the precisely aligned rows of OHCs in the same way as electromechanical ripples do between the interdigital electrodes of a SAW resonator. The distance OHC1–OHC3 is 1 wavelength (360 degrees phase delay). This mechanism is conjectured as providing the positive feedback and gain underlying the cochlear amplifier