Figure 6.

Conditions for the elastic propagating waves in the OCC model to appear under uniformly distributed stimulation. Besides the stiffness gradient, three conditions were required for the existence of the propagating wave under uniform stimulation. Sinusoidal force (21.5 kHz) was uniformly distributed along the midline of the basilar membrane. The basilar membrane displacement (top) and the phase with respect to the stimulation (bottom) were plotted. (A) When there was no elastic longitudinal coupling (all longitudinal beams and the DCpp were removed), the propagating waves were not present. The Z-degrees of freedom were constrained (dZ = 0) to stabilize the structure. (B) When the distance between the tips of the outer hair cell and the DCpp was set to zero (s = 0), the propagating waves were not present. (C) Without outer hair cell motility, despite reduced viscous damping, there were no propagating waves.