| Other speakers at this meeting will describe the hair bundles that act as vibration sensors in the inner ear of amphibians and the corresponding sensory organ in insects. Despite their very different physical structure, these organs share a common feature: both are active mechanical systems that appear to be poised on the verge of an oscillatory instability. What do these recent discoveries tell us about human hearing? We have proposed that 'critical oscillators' might also play a key role in the mammalian cochlea. The situation is considerably more complex in this case, because the sensory cells sit on a flexible membrane and their motion is coupled via the cochlea fluid. As a result, a sound stimulus generates an active, nonlinear travelling wave that moves along the cochlea. I will discuss how this mechanism transports sound of a given frequency to a particular place in the cochlea and show that the model accords with a variety of data from physiological and psychoacoustic experiments. |
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