Influence of change in frequency on the movement of sound sources induced by interaural time differences

When a tone-burst train with a short inter-burst interval is lateralized to the left and is followed by another tone-burst train lateralized to the right, listeners report a smooth shift of tone bursts along the intracranial axis from left to right (known as auditory saltation). When a sequence of tone bursts with a changing interaural time difference is presented, listeners also report a smooth shift of tone bursts (simulated auditory motion). In this study, an investigation was carried out to determine whether the movement of sound sources, such as auditory saltation and simulated auditory motion, are influenced by changes in frequency between or across tone bursts. The results show that abrupt changes in frequency hamper the perceived smoothness of auditory saltation and simulated auditory motion. In contrast, gradual changes in frequency retain the smoothness of auditory saltation and simulated auditory motion. These results indicate that perceptual grouping based on frequency of tone bursts influences the smoothness of the movement of sound sources.