Abstract
The mechanism of disfluency was investigated from the viewpoint of voice control by feedback. Four normal adult subjects recited three melodies with the syllable /pa/, consisting of five tones and five beats per second, under 10 conditions of 0-900ms (100ms steps) delayed auditory feedback (DAF). The DAF effect was analyzed by soundspectrogram and measured by the frequency of /pa/ in each DAF condition.
All the subjects had the most disfluencies on the most complex melody, the second most on a less complex melody, and the least on the simplest. The maximum DAF effect was observed under conditions of 100-300ms delay time. Analysis of soundspectrograms revealed that disfluency was induced when the simultaneous feedback was disturbed by the delayed feedback.
It was considered that disfluency was a reaction to cognitive discrepancy between target values and those caused by feedback.
