The human cochlear mechanical nonlinearity inferred through the Schairer et al. (2003) model

Schairer et al. (2003) hypothesized that a multiplicative internal sensory noise, combined with the cochlear mechanical nonlinearity, causes a probe’s detection threshold under forward-masking to systematically determine its psychometric function’s slope. Here, psychometric functions of unprecedented precision are shown for forward-masked probe-tone detection as a function of intensity of same-frequency forward-masker at fixed masker-probe time gap. Within the Schairer et al. model, these psychometric functions imply that the cochlear nonlinearity’s rate-of-change declines as a power function of dB SPL. Rates-of-change, once integrated, give the hypothetical nonlinearity itself, as a function of a single unknown parameter for which suitable values are inferred by comparing hypothetical rates-of-change in man to actual rates-of-change in animals. The model cochlear mechanical nonlinearity in man has similar magnitude and shape to those in animals. Schairer et al. (2003) introduced a model of the hypothetical influence of the cochlear compressive mechanical nonlinearity upon the slopes of psychometric functions for probe detection under forward-masking. The present paper presents psychometric functions fo