This study analyzes a waveguide consisting of two parallel fluidfilled chambers connected by a narrow slit that is spanned by two coupled elastic beams. A stiffness gradient exists in the longitudinal direction. This simple linear system, which contains no lumped mass, is shown to act as a spectral analyzer. Fluid waves traveling in the waveguide exhibit a distinct amplitude peak at a longitudinal location that varies systematically with frequency. The peaking is not based on resonance, but entirely on wave dispersion. When entering its peak region, the wave undergoes a sharp deceleration associated with a transition in which two propagation modes exchange roles. It is proposed that this mode shape swapping underlies the frequency analysis of the mammalian cochlea.

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doi.org/10.1073/pnas.1412412111, hdl.handle.net/1765/90398
Proceedings of the National Academy of Sciences of the United States of America
Department of Neuroscience

van der Heijden, M. (2014). Frequency selectivity without resonance in a fluid waveguide. Proceedings of the National Academy of Sciences of the United States of America, 111(40), 14548–14552. doi:10.1073/pnas.1412412111