Nonmonotic behaviour of (2f1 - f2) explained by a saturation-feedback model

A rough approximation of the saturation-feedback model is used to calculate the dependence of the (2f1 - f2) difference tone on the level L1 of the lower primary. The calculated data are in astonishingly good agreement with measured data, indicating that the cubic difference tone is a vector sum composed from many partials. These partials are derived through a nonlinear saturation characteristic with a knee point corresponding to 40 dB SPL from the excitation-time functions produced by the two primaries along the basilar membrane.