Live demonstration of a physical model of the active cochlea
Tina Jovic, Curtis King, Richard D. Rabbitt · The Journal of the Acoustical Society of America · 2007
An active physical model of the cochlea was constructed to mimic the nonlinear amplification carried out by the human cochlea. The model includes hair-cell cilia-like sensors to measure the local velocity of the fluid, and electromagnetic actuators to actively feed energy back into the motion. The model is outfitted with an electromagnetic shaker (mimicking the eardrum) to deliver complex waveforms to a piston (mimicking the stapes). Since the model is much larger than the cochlea, its best response frequencies are shifted down in the spectrum. The most interesting responses are obtained when music is recorded in stereo, digitally processed, and replayed into the model. One channel is frequency shifted to match the best frequencies of the model while the other channel is played acoustically without modification. This allows the listener to observe the motion of the cochlear partition in temporal synchrony with hearing the original soundtrack. A live demonstration of the apparatus in response to pure tones, speech, and music will be presented under both passive and active conditions. [Work supported in part by NIDCD R01 DC04928.]