[no subject]

[Robert Withnell <rwithnel@xxxxxxxxxxx>]

Andrew Bell continues to question the exiting notion that energy
propagation in the cochlea involves an inertially-mediated fluid flow
coupled in to the basilar membrane as a traveling wave. He cites a recent
paper by Tianying Ren in Nature Neuroscience as evidence that the reverse
propagation of energy does not involve such a traveling wave. As observed
by David Mountain, the experimental design of Ren does not exclude a
reverse traveling wave. For measurement on the basilar membrane to
elucidate a reverse traveling wave requires that the reverse traveling wave
be larger in magnitude than any forward traveling wave at the same
frequency. This is most likely at a point basal to f2 - at a stimulus
frequency ratio that results in a 2f1-f2 DP generated from the nonlinear
interaction of f1 and f2 that is larger in the reverse than the forward
direction.

Comments by Martin Braun:
> He did address the reverse traveling wave issue, and he found there is none.
> He simultaneous measured stapes vibration and found that, for DPs, it
> preceded that of BM vibration.
It is possible that Ren's phase-gradient data for stapes vibration involves
a wrapping error. Regardless of whether the reverse propagation of energy
involves a reverse traveling wave or a compressional wave, there is the
little issue of causality if the stapes vibration precedes the generation
of the source energy.

Robert Withnell