Research Note  |   October 2009
Direct Magnitude Estimation of Articulation Rate in Boys With Fragile X Syndrome
 
Author Affiliations & Notes
  • David J. Zajac
    Craniofacial Center, University of North Carolina at Chapel Hill
  • Adrianne A. Harris
    FPG Child Development Institute, University of North Carolina at Chapel Hill
  • Joanne E. Roberts
    FPG Child Development Institute, University of North Carolina at Chapel Hill
  • Gary E. Martin
    FPG Child Development Institute, University of North Carolina at Chapel Hill
  • Contact author: David J. Zajac, University of North Carolina Craniofacial Center, CB No. 7450, Chapel Hill, NC 27599. E-mail: david_zajac@dentistry.unc.edu.
Article Information
Special Populations / Genetic & Congenital Disorders / Speech, Voice & Prosody / Speech
Research Note   |   October 2009
Direct Magnitude Estimation of Articulation Rate in Boys With Fragile X Syndrome
Journal of Speech, Language, and Hearing Research, October 2009, Vol. 52, 1370-1379. doi:10.1044/1092-4388(2009/07-0208)
History: Received September 5, 2007 , Revised July 28, 2008 , Accepted January 7, 2009
 
Journal of Speech, Language, and Hearing Research, October 2009, Vol. 52, 1370-1379. doi:10.1044/1092-4388(2009/07-0208)
History: Received September 5, 2007; Revised July 28, 2008; Accepted January 7, 2009
Web of Science® Times Cited: 4

Purpose: To compare the perceived articulation rate of boys with fragile X syndrome (FXS) with that of chronologically age-matched (CA) boys and to determine segmental and/or prosodic factors that account for perceived rate.

Method: Ten listeners used direct magnitude estimation procedures to judge the articulation rates of 7 boys with FXS only, 5 boys with FXS and a diagnosis of autism spectrum disorder (ASD), and 12 CA boys during sentence repetition. Sentences had similar articulation rates in syllables per second as determined acoustically. Four segmental/prosodic factors were used to predict perceived rate: (a) percentage consonants correct, (b) overall fundamental frequency (F0) level, (c) sentence-final F0 drop, and (d) acoustically determined articulation rate with the final word of the sentence excluded.

Results: Boys with FXS and ASD were judged to talk faster than CA controls. Multiple linear regression indicated that articulation rate with the final word of the sentence excluded and sentence-final F0 drop accounted for 91% of the variance for perceived rate.

Conclusions: Descriptions of speakers with FXS as having fast and/or fluctuating articulation rates may be influenced by autism status. Also, atypical sentence-final prosody may be related to perceived rate in boys with FXS and ASD.

Acknowledgments
The work reported in this article was supported by National Institutes of Health Grants R01 HD44935 and R03 HD40640. Portions of this article were presented at the 2008 Annual Convention of the American Speech-Language-Hearing Association, Chicago.
We thank Gary Weismer for his input on a previous version of this article; Kerry Callahan-Mandulak for assistance with data collection; Jackie Assal, Sarah Brehm, and Bruno Estigarribia for assistance with acoustic data analysis; and John Sideris and Jan Misenhiemer for assistance with statistical analysis.
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