  The cochlea has long been the subject of investigation in various research
fields due to its intriguing spiral architecture and unique sensing
characteristics. One of its most interesting features is the ability to sense
acoustic waves at different spatial locations, based on their frequency
content. In this work, we propose a novel design for a tonotopic resonator,
based on a cochlea-inspired spiral. The resulting structure was subjected to an
optimization process to exhibit out-of-plane vibration modes with mean
out-of-plane displacement maxima distributed along its centerline spanning
nearly a two-decade frequency range. Numerical simulations are performed to
demonstrate the concept, which is also confirmed experimentally on a 3D printed
structure. The obtained frequency-dependent distribution is shown to be a
viable source of information for the discrimination of signals with various
frequency components. The harnessed tonotopic features can be used as a
fundamental principle to design structures with applications in areas such as
non-destructive testing and vibration attenuation.
