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Vassilakis, P.N. (2002).  Dichotic sound interference products, sound localization cues, and binaural interaction at a neural level.  J. Acoust. Soc. Am., 112(5/2): 2299 (presented at the 144th meeting of the Acoustical Society of America - 1st Pan-American/Iberian Meeting on Acoustics, Cancun, Mexico).


The possibility of sound interference products arising from neural wave interaction is re-examined through five dichotic experiments. It is argued that interference percepts do not arise unless sound waves interact physically. Experiment-1 examines the possibility of beating for diotic sine stimuli. In this case, diplacusis would introduce beating if neural wave interaction could result in interference products. No beating was observed. Experiments-2a-2b &-2c examine the effect of dichotic phase changes on sine stimuli in terms of loudness, direction, and stereo-image-width. It is shown that such phase changes lead to perceptions incompatible with the interference principle and consistent with claims of binaural phase differences as sound-localization cues. Experiment-3 uses two-component dichotic stimuli. The results indicate that, when two sines with slightly different frequencies are presented dichotically, the constantly shifting phase between them effects a constantly shifting localization of the two-component complex stimulus. Depending on the frequency difference, this shift may be interpreted as a perceived rotation of the sound and/or a timbral fluctuation, often confused with loudness fluctuation. The findings do not support the claim of sound interference products arising from neural wave interaction. They are consistent with sound localization studies and indicate that the dichotic beats reported previously must have been a misidentified rotating sensation.