Variables affecting stutterer's initial reactions to delayed auditory feedback.

Twenty male stutterers (7-18 years) described pictures under delayed auditory feedback (DAF). Delay was varied from 0 to 300 msec in 50 msec steps. There was a significant interaction between delay time, age and initial disfluency in terms of disfluent words but not speech rate. Young stutterers (7-12 years) were generally more affected by DAF than older stutterers (13-18 years). Under DAF high disfluent stutterers showed reduced disfluency, whereas low disfluent stutterers either showed little or no change or became more disfluent. Delays of 50-150 msec tended to have an ameliorative effect on stuttering. Conflicting results were obtained when the same subjects repeated short sentences under DAF. The majority of stutterers were fluent when repeating the sentences under no delay, but stuttering increased under DAF. Current explanations of the DAF effect and feedback theories of stuttering do not readily account for these results.