Basilar membrane tonotopicity in the hook region of the cat cochlea.

Middle-ear to basilar membrane (BM) velocity transfer functions are reported for seven locations in the hook region of a single cat cochlea. These transfer functions were recorded at high sound pressure levels in a linearized, or passive cochlea, and resemble those reported previously by Wilson and Evans (1983). They demonstrate longitudinal tonotopicity with a gradient of approximately 3.6 mm/octave. When allowances are made for the nonlinear mechanisms previously demonstrated in active hook region preparations (Cooper and Rhode, 1992), the data are also consistent with the tonotopic map derived from the intracellular dye-filling studies of Liberman (1982).