Psychophysical measures of two-tone suppression and distortion products (2f1-f2) and (f2-f1).

Psychophysical two-tone suppression and the growth of the (2f1-f2) and (f2-f1) distortion products were measured in four normal-hearing young adults using a forward-masking paradigm. The stimulus parameters investigated were: (1) f1 = 750 and 3000 Hz; (2) f2/f1 = 1.11, 1.26, and 1.41; (3) L1 = 50, 65, 80, and 90 dB SPL; and (4) L2 - L1 varied from -20 to +20 dB in 10-dB increments. It appears that the p-law class of nonlinearity, which maintains that suppression and growth functions for the distortion products are directly related, is not supported by the data. Of existing models of aural nonlinearity, Goldstein's [J. Acoust. Soc. Am. 41, 458-479 (1967)] normalized power series appears to provide the most accurate description of the data, especially when modifications brought about by suppression are incorporated into the model.