RESUMO
The perceptual tone/noise ratio was measured for merged iterated ripple noise stimuli (IRNs) in which one of the individual IRNs always had a delay of 16 ms. The second IRN was chosen to create merged IRNs with single octave delay ratios (e.g., 16 ms:8 ms), double octave delay ratios (e.g., 16 ms:4 ms), harmonic delay ratios (e.g., 16 ms:12 ms), and nonharmonic delay ratios (e.g., 16 ms:3.9 ms). All stimuli were high-pass filtered at 800 Hz. The tone/noise ratio was significantly enhanced for the octave ratios, and there was a strong interaction between the single and double octave delay ratios and number of iterations. But, the perceptual tone/noise ratio for nonoctave ratios was determined solely by the number of iterations. The pattern of the results can be explained in terms of the height of the largest peak in the summary autocorrelogram [Meddis and Hewitt, J. Acoust. Soc. Am. 89, 2866-2882 (1991)] provided the model is modified to improve the simulation of the loss of phase locking.
