Intermodulation product pair 2f1 +/- fh: masking and growth

To examine the question of whether the distortion product 2f1 - fh is unique--whether a special nonlinear mechanism is responsible for its production--estimates of 2f1 - fh and of 2f1 + fh amplitudes were obtained in three listeners. Threshold shifts measured with a tone-on-tone masking paradigm for each distortion product suggest that each have similar properties and are masked by other tones as if they had a physical realization in the cochlea. Their masking is not a function of stimulus fine-time structure. The 1 dB/dB growth of 2f1 - fh was not changed by rendering it inaudible as previously suggested. Possible explanations of the 1 dB/dB growth of 2f1 - fh compared with the accelerated growth of 2f1 + fh are examined.