The nuts and bolts of the inner ear - or how to understand high frequency hearing

Mammalian hearing mechanisms depend on an interplay between properties of the component cells the structural mechanics and the fluids of the cochlea.

It is well known that our auditory range extends at most to about 20 kHz, but the range in some species can extend to over 100 kHz. There has been significant progress recently in identifying key molecular components, but there remain issues around their physiological integration.

In particular, it is thought that the mechanics of the cochlea is largely determined by a subpopulation of sensory cells, the outer hair cells (OHCs): when they are damaged hearing sensitivity lost. The problem is that OHC “electromotility” – a fast voltage-dependent force production by the cells - may be frequency limited, a conclusion arising from both in vitro and in vivo experiments.

In this talk, I shall describe some of the background to current thinking about cochlear function and suggest that high frequency hearing, very obvious in rodents, may be understood by invoking a particular piezo-electric feature of OHCs.

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