ASA 127th Meeting M.I.T. 1994 June 6-10

3pPP1. Binaural beats of mistuned consonances.

M. Patrick Feeney

Dept. of Otolaryngol., RL-30, Univ. of Washington, Seattle, WA 98195

Edward M. Burns

G-15, Univ. of Washington, Seattle, WA

In a previous paper [M. P. Feeney and E. M. Burns, J. Acoust. Soc. Am. 93, 2346(A) (1993)] data on the detection of dichotic beats of mistuned consonances (BMCs) were presented. The results showed that subjects could detect mistuning from small-integer frequency ratios for simultaneous-dichotic pure-tones in a 2I-2AFC task. However, there was no conclusive proof that they were using ``beats'' as the cue, nor conclusive evidence that this was a ``binaural'' phenomenon, i.e., that detection involved any fusion or lateralization percept. Here, the results of two ``control experiments'' suggested by alert audience members A. J. M. Houtsma and C. Trahiotis are presented. In the first experiment, subjects were asked to adjust simultaneous-dichotic octaves, using a ``beat-minimization'' as the criterion. The subject's variability in this task was much smaller than their variability for adjustments of melodic octaves. In the second experiment, listeners were able to detect intracranial movement between ``frozen'' dichotic BMCs. Further data on the ability of subjects to detect mistuning from small-integer frequency ratios for dichotic modulation envelopes are also presented. Taken together, the results suggest that dichotic BMCs are beats, are binaural, and are an example of cross-channel processing. [Work supported by the Virginia Merrill Bloedel Hearing Research Center.]