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.
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: Accepted 07 Jan 2009 , Received 05 Sep 2007 , Revised 28 Jul 2008
Journal of Speech, Language, and Hearing Research October 2009, Vol.52, 1370-1379. doi:10.1044/1092-4388(2009/07-0208)
History: Accepted 07 Jan 2009 , Received 05 Sep 2007 , Revised 28 Jul 2008

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.

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