Auditory sensitivity to temporal deviations from perceptual isochrony: Comparison of the starting point and ending point of acoustic change1

Abstract

Abstract: The occurrence of a sound event in a sound stream can be perceived without difficulty even when it is difficult to define the acoustic boundary. This study was designed to investigate which acoustical feature functions as an effective cue to “mark” the occurrence of a new event. When two steady sounds are connected by a short frequency glide, at which point do we perceive the occurrence of the second sound: the starting point of the frequency glide or its ending point? To answer this question, experimental stimuli were designed to establish an isochronous structure that was conveyed exclusively by the starting or by the ending point of the glide. The frequency glide was made by modulating the carrier frequency of a sinusoid or the resonant frequency of a complex tone. In two experiments, the deviation from the isochronous structure was detected more easily under the starting‐point condition than under the ending‐point condition. The results suggest that the starting point functions as a more effective cue for marking a new event than does the ending point.