Date of Award
Master of Arts
Speech, Language and Hearing Sciences
Dr. John Hanley
Dr. James Hillenbrand
Dr. Larry Oppliger
Masters Thesis-Open Access
Pitch and amplitude perturbation values were compared for nine adult stutterers and nine adult nonstutterers. Each subject produced ten sustained phonations of the vowels /a/ and /i/. An automatic pitch-synchronous autocorrelation fundamental frequency tracker was used to extract period and amplitude measures.
Findings revealed that: (a) stutterers had significantly more vocal shimmer than nonstutterers (p = .01), (b) F-ratios for percent jitter between groups approached (p = .07) but did not reach significance, and (c) the vowel /a/ was produced with higher levels of jitter and shimmer than the vowel /i/. Results support the notion that instability of the vocalization process is present in stutterers during fluent utterances. The potential usefulness of acoustic perturbation measures in understanding, diagnosing, and treating the disorder of stuttering is discussed.
Bamberg, Carmen M., "An Investigation of Pitch Perturbation and Vocal Intensity Characteristics of Stutterers and Nonstutterers" (1989). Masters Theses. 1112.