Fundamental Frequency, Intensity, and Vowel Selection: Effects on Measures of Phonatory Stability Measures of phonatory stability such as jitter, shimmer, and signal-to-noise ratio (SNR) are increasingly used in clinics and laboratories, yet questions about the effects of various aspects of voice production on these acoustic variables have received only limited attention. The purpose of the present study was to examine the effects ... Research Article
Research Article  |   December 01, 1995
Fundamental Frequency, Intensity, and Vowel Selection: Effects on Measures of Phonatory Stability
 
Author Affiliations & Notes
  • Marylou Pausewang Gelfer
    University of Wisconsin-Milwaukee
  • Contact author: Marylou Pausewang Geifer, PhD, Department of Communication Sciences and Disorders, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, Wl 53201. E-mail: gelfer@csd uwm.edu
Article Information
Speech, Voice & Prosody / Speech / Research Articles
Research Article   |   December 01, 1995
Fundamental Frequency, Intensity, and Vowel Selection: Effects on Measures of Phonatory Stability
Journal of Speech, Language, and Hearing Research, December 1995, Vol. 38, 1189-1198. doi:10.1044/jshr.3806.1189
History: Received June 28, 1994 , Accepted March 28, 1995
 
Journal of Speech, Language, and Hearing Research, December 1995, Vol. 38, 1189-1198. doi:10.1044/jshr.3806.1189
History: Received June 28, 1994; Accepted March 28, 1995

Measures of phonatory stability such as jitter, shimmer, and signal-to-noise ratio (SNR) are increasingly used in clinics and laboratories, yet questions about the effects of various aspects of voice production on these acoustic variables have received only limited attention. The purpose of the present study was to examine the effects of frequency, intensity, and vowel selection on those measures of phonatory stability. Twenty-nine young adult females were used as subjects. Each subject produced vocalizations at her speaking fundamental frequency (SFF) and one octave above SFF; at 60, 70, and 80 dB; and on the vowels /i/ and /a/, for a total of 12 vocalizations per subject. These vocalizations were then analyzed, using CSpeech acoustic analysis software, to obtain measures of jitter, shimmer, and SNR. Results revealed that frequency, intensity, and vowel selection all affected various phonatory stability measures, with the highest perturbation values almost always occurring in the low frequency-low intensity condition. Implications and physiological explanations for the results of the study were presented.

Acknowledgments
Parts of this paper were presented at the Annual Convention of the American Speech-Language-Hearing Association in San Antonio, Texas, November 1992. The author would like to thank Lorraine Olson Ramig, E. Thomas Doherty, and two anonymous reviewers, for their valuable comments and suggestions on earlier drafts of this manuscript.
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