Now hear this: Simple fluid waveguide performs spectral analysis in a manner similar to the cochlea
(Phys.org) —Within the mammalian inner ear, or cochlea, a remarkable but and long-debated phenomenon occurs: As they move from the base of the cochlea to its apex, traveling fluid waves – that is, surface waves, in which (like waves on the sea and or in a canal) water moves both longitudinally and transversally – peak in amplitude at locations that depend on the wave's frequency. (Higher frequencies are concentrated in the base, lower frequencies in the apex.) What's critical is that these peaks allow us to identify and separate sounds. While cochlear frequency selectivity is typically explained by local resonances, this idea has two problems: resonance-based models require excessive intracochlear mass, and moreover cannot accurately represent the cochlea's production of both phase and amplitude information. Recently, however, Prof. Marcel van der Heijden at Erasmus Medical Center, University Medical Center, Rotterdam, has rejected resonance, and in its place has designed and...