A realizable cochlear model using feedback from motile outer hair cells

A physically realizable form of a recent cochlear model using feedback forces from motile outer hair cells [Geisler (1991) Hear. Res. 54, 105-117] has been developed. The model was computer-simulated in the frequency domain (necessarily linear). Its responses to pure tones are very realistic in terms of sharpness (Q10s of 3-5) and in terms of tip-to-tail ratios (50-60 dB). These large tips are due to the feedback forces, which act as negative resistances (energy-supplying elements) over restricted spatial ranges. Nyquist-criterion analysis indicates that the model is stable. The spatial patterns of the model's output also bear qualitative resemblances to several other phenomena observed in cochleas, both living and excised.