Pitch strength of iterated rippled noise when the pitch is ambiguous.

Two versions of a cascade of delay, gain following delay, and add circuits were used to generate iterated rippled noise (IRN) stimuli. IRN stimuli produce a repetition pitch whose pitch strength relative to the noise percept can be varied by changing the type of circuit, the attenuation, or the number of iterations in the circuit. The repetition pitch of IRN is different when the delayed noise is subtracted (gain < 0) rather than added (gain > 0) to the undelayed noise. In the case of subtraction, IRN pitch is often ambiguous having two or more pitches. Listeners were asked to use pitch strength to discriminate between various pairs of IRN stimuli generated with different gains, different network circuits, and different number of iterations. For most conditions the gain was less than one. The data were described by a description based on an exponential function of the largest peak of the autocorrelation function of IRN stimuli [W. A. Yost, J. Acoust. Soc. Am. 100, 511-518 (1996)] processed such that the spectral dominance region is emphasized. These results suggest that the strength of the pitch of IRN stimuli can be described by temporal processing mechanisms as might be revealed by autocorrelation.