An Acoustical Study of the Fricative /s/ in the Speech of Individuals With Dysarthria This paper reports on measurements of several acoustic attributes of the fricative consonant /s/ produced in word-initial position by normally speaking adults and by speakers with neuromotor dysfunctions. Several acoustic properties are evaluated: the spectrum shape of the fricative and its amplitude in relation to the following vowel, the presence ... Research Article
Research Article  |   December 01, 2001
An Acoustical Study of the Fricative /s/ in the Speech of Individuals With Dysarthria
 
Author Affiliations & Notes
  • Helen Chen
    Research Laboratory of Electronics Massachusetts Institute of Technology Cambridge
  • Kenneth N. Stevens
    Research Laboratory of Electronics Massachusetts Institute of Technology Cambridge
  • Corresponding author: e-mail: stevens@speech.mit.edu
  • Currently affiliated with Akamai Technologies, Cambridge, MA
    Currently affiliated with Akamai Technologies, Cambridge, MA×
Article Information
Speech, Voice & Prosodic Disorders / Dysarthria / Hearing & Speech Perception / Acoustics / Speech, Voice & Prosody / Speech / Research Articles
Research Article   |   December 01, 2001
An Acoustical Study of the Fricative /s/ in the Speech of Individuals With Dysarthria
Journal of Speech, Language, and Hearing Research, December 2001, Vol. 44, 1300-1314. doi:10.1044/1092-4388(2001/101)
History: Received April 24, 2001 , Accepted August 15, 2001
 
Journal of Speech, Language, and Hearing Research, December 2001, Vol. 44, 1300-1314. doi:10.1044/1092-4388(2001/101)
History: Received April 24, 2001; Accepted August 15, 2001
Web of Science® Times Cited: 9

This paper reports on measurements of several acoustic attributes of the fricative consonant /s/ produced in word-initial position by normally speaking adults and by speakers with neuromotor dysfunctions. Several acoustic properties are evaluated: the spectrum shape of the fricative and its amplitude in relation to the following vowel, the presence or absence of voicing, the time variation of the spectrum during the fricative and in the transition to the following vowel, and the presence of inappropriate acoustic patterns preceding the /s/. Some of these properties are based on quantitative measurements of the spectrum of the /s/, and others are based on observations of the time-varying acoustic patterns in spectrograms. For the individuals with dysarthria, deviations of each of these properties from the normal range are interpreted in terms of specific deficits in the control of the speech-production system. For the most part, these parameters are highly correlated with the speakers' overall intelligibility, with the intelligibility of words containing the fricative /s/, and with perceptual ratings of the adequacy of the fricative production. The parameters that show the best correlation with intelligibility and perceptual ratings are (a) measures of deviations from normalcy in the time variation of the acoustic pattern within the consonant and at the consonant-vowel boundary and (b) the spectrum shape of the frication noise. These acoustic parameters are related to deviations in the temporal pattern of control of the articulators in producing fricative-vowel sequences and to lack of fine control of the tongue blade in achieving an appropriate target configuration for the fricative.

Acknowledgments
This research was funded by Grant No. DC00075 from the National Institutes of Health. Our gratitude goes to HwaPing Chang, whose carefully documented doctoral research laid a solid foundation for this study. We thank Melanie Matthies for her assistance with the statistical analysis. We acknowledge with thanks AP, JW, LD, ES, and KC, who served as participants. Thanks also go to Jeff Kuo, Marilyn Chen, and Kelly Poort for their helpful critique of this work.
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