Influence of Delayed Auditory Feedback (DAF) on Vocal Rhythm

Abstract

The purpose of the present study was to compare vocal rhythms of normal persons, including children, the young and the old, with those of persons having speech defects, including the mentally retarded, stutterers and aphasics. Each subject phonated /a/ with 4-2 rhythm under DAF condition (delay time; 50-500 msec) . The phonated sound was recorded in tape and analysed with respect to phonation time and rhythm change.
As for normal subjects, the young could phonate /a/ most rhythmically, less influenced by DAF, on the contrary the children's phonations were rremarkably affected by DAF. The old's phonation patterns were a little influenced by DAF.
The phonation patterns of aphasics were similar to those of the old, and the patterns of the mentally retarded showed those of normal children. However, the stutterers' phonations were greatly influenced by DAF.
DAF-effect was the greatest under delay time 300 msec for all subject-groups, normal and abnormal.