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.

Auditory filter, Avoided crossing, Group velocity, Hydrodynamics, Tonotopy
dx.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