Date of Graduation


Document Type


Degree Type



College of Education and Human Services


Communication Sciences and Disorders

Committee Chair

Kenneth O. St. Louis.


It has been commonly assumed that as people speak faster, they speak in higher vocal fundamental frequencies. Since the frequency and intensity often vary together, vocal intensity is expected to increase with speaking rate as well. The purpose of this study was to explore how speaking rate affects vocal fundamental frequency and intensity during diadochokinetic speaking tasks in normal speaking adults. Twenty-four normal young adults, 12 male and 12 female, were asked to repeat the syllables "/pLambda/, /pLambda-t[schwa]/, and /pLambda-t[schwa]-k[schwa]/" at a self-selected comfortable rate, then at a slow rate modeled about one syllable per second, and finally at their maximum rate. It was hypothesized that increasing the speaking rate from slow to comfortable, and comfortable to fast would increase fundamental frequency and intensity. All experimental speech segments were recorded to the Computerized Speech Lab (CSL) program through a head-mounted microphone. The results showed significant increases in fundamental frequency for both males and females as a function of rate increase for all three diadochokinetic tasks, as hypothesized. However, intensity did not increase as a function of rate increase but varied with syllables and sex of the participants. The results suggest that fundamental frequency increases independent of intensity as a function of rate increase in diadochokinetic tasks. It is likely that rapid speech fosters an increase in the longitudinal tension in the vocal folds, which therefore increases fundamental frequency while the vocal intensity is maintained.