Mimicking the cochlea with an active acoustic metamaterial
Résumé
The human ear is a fascinating sensor, as it can detect sounds over three decades of frequency and twelve orders of magnitudes. However, these extraordinary properties have a cost, since the ear can distort sounds and give rise to acoustic illusions such as the phantom notes of Tartini. Here, following a proposed model [1] which has yet to be universally accepted, we mimic a living cochlea using an active acoustic metamaterial. It is implemented using a set of active acoustic resonators which function near a Hopf bifurcation, and which display an adiabatic gradient of index. We demonstrate that the designed metamaterial sensor mimics all the salient characteristics observed in the measured dynamic responses of both the dead and the living cochleae [2]. Our results offer new insights into the physiology of the mammalian?s cochlea and pave the way for the development of a new generation of highly sensitive bio-inspired acoustic sensors. [1] Duke, T. and F. J�licher, ?Active traveling wave in the cochlea,? Phys. Rev. Lett., Vol. 90, 158101, 2003 [2] M. Rupin, G. Lerosey, J. de Rosny, F. Lemoult, ?Mimicking the cochlea with an active acoustic metamaterial?, New Journal of Physics, 21 (9), 093012, 2019