Effects of noise and rhythmic stimulation on the speech of stutterers.

This study was designed to investigate the effects of noise and rhythmic stimulation on stutterers' vocal fundamental frequency, vowel duration, and vocal level, and the relation these variables have to one another and to stuttering during noise and rhythmic stimulation. Measurements of speech variables were obtained from audio and graphic-level recordings and from narrow- and broad-band spectrograms. Results indicated that stuttering was significantly reduced during noise and rhythmic stimulation with the reduction during rhythmic stimulation being significantly greater than the reduction during noise. Decreases in stuttering were correlated with increases in vowel duration during both conditions for seven of nine subjects. We interpret our findings to suggest that temporal changes in speech production are related to the decrease in stuttering that occurs during noise and rhythmic stimulation.