Influence of the Non-Linearity of the Hearing System on its Frequency Selectivity

Masking patterns produced by critical band wide noise, by one tone, and by complexes of two, three and five tones of close frequency are compared. The levels of difference tones, necessary for the compensation of internally produced difference tones of uneven order are measured as function of both level and frequency separation of the two primary tones. A comparison between the results of the two series of measurements indicates that the nonlinearity of the hearing system influences its frequency selectivity in such a way that sinusoidal tones reflect the largest but leveldependent selectivity; narrow band noises, however — as a consequence of the additional spectra produced by the ear — simulate a less pronounced but almost level-independent frequency selectivity.