A Note on Vowel Centralization in Stuttering and Nonstuttering Individuals Inferences were made regarding vocal tract vowel space during fluently produced utterances through examination of the first two formant frequencies. Fifteen adult males served as subjects, representing separate groups of untreated and treated individuals who stutter and nonstuttering controls. The steady-state portion of formant one (F1) and formant two (F2) ... Research Note
Research Note  |   October 01, 1998
A Note on Vowel Centralization in Stuttering and Nonstuttering Individuals
 
Author Affiliations & Notes
  • Michael Blomgren
    University of Connecticut Storrs
  • Michael Robb
    University of Connecticut Storrs
  • Yang Chen
    University of Connecticut Storrs
  • Contact author: Michael Blomgren, Department of Communication Sciences, University of Connecticut, 850 Bolton Road, U-85, Storrs, CT 06269 e-mail: mib95003@uconnvm.uconn.edu
Article Information
Speech, Voice & Prosodic Disorders / Fluency Disorders / Speech, Voice & Prosody / Speech / Research Note
Research Note   |   October 01, 1998
A Note on Vowel Centralization in Stuttering and Nonstuttering Individuals
Journal of Speech, Language, and Hearing Research, October 1998, Vol. 41, 1042-1051. doi:10.1044/jslhr.4105.1042
History: Received March 13, 1998 , Accepted May 15, 1998
 
Journal of Speech, Language, and Hearing Research, October 1998, Vol. 41, 1042-1051. doi:10.1044/jslhr.4105.1042
History: Received March 13, 1998; Accepted May 15, 1998

Inferences were made regarding vocal tract vowel space during fluently produced utterances through examination of the first two formant frequencies. Fifteen adult males served as subjects, representing separate groups of untreated and treated individuals who stutter and nonstuttering controls. The steady-state portion of formant one (F1) and formant two (F2) was examined in the production of various CVC tokens containing the vowels /i/, /u/, and /α/. Vocal tract vowel space was estimated three ways. The first analysis scheme involved measurement of formant frequency spacing. The second measure involved calculating the area of the vowel space triangle. The third measure was based on calculating the average Euclidean distance from each subject's midpoint "centroid" vocal tract position to the corresponding /i/, /u/, and /α/ points on the vowel triangle. The formant frequency spacing measures proved to be most revealing of group differences, with the untreated stutterers showing significantly greater vowel centralization than the treated group and control group. Discussion focuses on the vocal tract articulation characterizing fluent speech productions and possible treatment implications for persons who stutter.

Acknowledgments
This study was completed by the first and third authors as part of a doctoral research apprenticeship directed by the second author. We wish to thank Can and Catherine Erkey who provided assistance with the vocal tract area calculations.
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