Figure 1.

Sagittal space-time slice through the symmetric two-dimensional box model of height H. The middle and external ears are represented by using balls and sticks. The cochlear partition is shown vibrating in response to a pure tone stimulus (P_stim) applied in the ear canal. Micromechanical irregularities (bottom panel) arising from the discrete cellular architecture of the organ of Corti appear superposed on the smooth secular variation of mechanical characteristics from base to apex. Analysis of the model equations shows that irregularities in any mechanical parameter (e.g., the effective damping) give rise to reverse-traveling waves that return to the ear canal as sound (P_SFOAE).