Temporal factors in the effects of masking noise on fluency of stutterers.

Nineteen stutterers read sentences under four conditions: continuous 95-db white noise over headphones; white noise preceding speech initiation; no white noise. White noise preceding speech initiation did not improve fluency, contrary to Webster's auditory interference theory. White noise presented following speech initiation led to shorter reading times and fewer disfluent words, especially for part-word repetitions. The more severe the stutterer, as measured by an external task, the greater was the ameliorative effect of auditory masking. Results indicated that white noise may attack a pathological condition existing in stutterers, and supported Timmons and Boudreau's (1972) adaptation model, which posits that stutterers have difficulty adapting to discrepancies in delays of auditory feedback through different channels.