Auditory tuning curves derive from constant basilar membrane velocity rather than displacement

Evidence

The displacement of the basilar membrane is the first stage in the sequence of the different auditory levels. For constant stimulus amplitude (pure tone of constant level of 80 dB SPL) the displacement at four locations, 4, 11, 20 and 29 mm from the helicotrema, is shown schematically in the upper part of Fig. 3.7 as a function of frequency on a logarithmic scale. The first temporal derivative, the velocity, often assumed to be the effective stimulus driving the inner haircells, is shown in part (b) of Fig. 3.7. Assuming a linear system, tuning curves can be constructed from part (b). Tuning curves show the amplitude of the stimulus necessary to produce a constant response magnitude at a certain place as a function of the stimulus frequency. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 224

Categorization

• DEFINE: Defines what a tuning curve is and why velocity, not displacement, is the presumed haircell-driving stimulus.