TRAVELING WAVES ... ON THE TECTORIAL MEMBRANE

We show that isolated sections of the TNT suspended in artificial endolymph support traveling waves of radial motion that propagate longitudinally. The velocities of the TM traveling waves are remarkably similar to those of basilar membrane (BM) near the best place. A simple model shows that these waves are intrinsic to the viscoelastic structure of the TM. Analysis of models of cochlear loads suggests that TM traveling waves are little affected by the stiffness of hair bundles and the limbal attachment or by viscous damping in the subtectorial space. TM waves are inconsistent with a fundamental assumption in "classical" cochlear macromechanical models: that adjacent longitudinal sections of the cochlea are coupled through the fluid alone. Also, cochlear micromechanics, which are conventionally envisioned as local processes that depend on just neighboring structures, must be rethought as a global process extending over significant longitudinal distances.