Perceived Trajectories of the Cyclic Movement of Sound Images

Binaural beats are a phenomenon occurring as a result of binaural integration during dichotic stimulation. This phenomenon is apparent as a cyclic movement of a sound image in subjective space when the beat frequency range is below 3 Hz. Subjects were presented with noise stimuli to create a sensation of motion due to a linear or stepwise pattern of changes in the interaural delay (ITD). The ranges of changes in ITD determined the position of the trajectories of motion in the central or lateral sectors of space. The results confirmed that both patterns of ITD created the effect of binaural beats. The effect of spatial position on perceived trajectory length is interpreted in terms of the nonlinear properties of lateralization. The effect of the ITD pattern on perceived trajectory length is presumptively mediated by the mechanisms of temporal integration operating in binaural hearing.