Effects of Alphabet-Supplemented Speech on Brain Activity of Listeners: An fMRI Study Purpose The purpose of this article was to examine the neural mechanisms associated with increases in speech intelligibility brought about through alphabet supplementation. Method Neurotypical participants listened to dysarthric speech while watching an accompanying video of a hand pointing to the 1st letter spoken of each word on ... Research Article
Research Article  |   October 01, 2015
Effects of Alphabet-Supplemented Speech on Brain Activity of Listeners: An fMRI Study
 
Author Affiliations & Notes
  • Kelene Fercho
    Basic Biomedical Sciences, University of South Dakota, Vermillion
    Center for Brain and Behavior Research, University of South Dakota, Vermillion
  • Lee A. Baugh
    Basic Biomedical Sciences, University of South Dakota, Vermillion
    Center for Brain and Behavior Research, University of South Dakota, Vermillion
  • Elizabeth K. Hanson
    Center for Brain and Behavior Research, University of South Dakota, Vermillion
    University of South Dakota, Vermillion
  • Disclosure: The authors have declared that no competing interests existed at the time of publication.
    Disclosure: The authors have declared that no competing interests existed at the time of publication. ×
  • Correspondence to Elizabeth K. Hanson: elizabeth.hanson@usd.edu
  • The two senior authors, Lee A. Baugh and Elizabeth K. Hanson, contributed equally to this article.
    The two senior authors, Lee A. Baugh and Elizabeth K. Hanson, contributed equally to this article.×
  • Editor: Jody Kreiman
    Editor: Jody Kreiman×
  • Associate Editor: Julie Liss
    Associate Editor: Julie Liss×
Article Information
Speech, Voice & Prosodic Disorders / Dysarthria / Speech / Research Articles
Research Article   |   October 01, 2015
Effects of Alphabet-Supplemented Speech on Brain Activity of Listeners: An fMRI Study
Journal of Speech, Language, and Hearing Research, October 2015, Vol. 58, 1452-1463. doi:10.1044/2015_JSLHR-S-14-0038
History: Received February 11, 2014 , Revised July 23, 2014 , Accepted July 8, 2015
 
Journal of Speech, Language, and Hearing Research, October 2015, Vol. 58, 1452-1463. doi:10.1044/2015_JSLHR-S-14-0038
History: Received February 11, 2014; Revised July 23, 2014; Accepted July 8, 2015

Purpose The purpose of this article was to examine the neural mechanisms associated with increases in speech intelligibility brought about through alphabet supplementation.

Method Neurotypical participants listened to dysarthric speech while watching an accompanying video of a hand pointing to the 1st letter spoken of each word on an alphabet display (treatment condition) or a scrambled display (control condition). Their hemodynamic response was measured with functional magnetic resonance imaging, using a sparse sampling event-related paradigm. Speech intelligibility was assessed via a forced-choice auditory identification task throughout the scanning session.

Results Alphabet supplementation was associated with significant increases in speech intelligibility. Further, alphabet supplementation increased activation in brain regions known to be involved in both auditory speech and visual letter perception above that seen with the scrambled display. Significant increases in functional activity were observed within the posterior to mid superior temporal sulcus/superior temporal gyrus during alphabet supplementation, regions known to be involved in speech processing and audiovisual integration.

Conclusion Alphabet supplementation is an effective tool for increasing the intelligibility of degraded speech and is associated with changes in activity within audiovisual integration sites. Changes in activity within the superior temporal sulcus/superior temporal gyrus may be related to the behavioral increases in intelligibility brought about by this augmented communication method.

Acknowledgments
The authors gratefully acknowledge the work of the radiology staff at Avera Sacred Heart Hospital in Yankton, South Dakota, and the indispensable research assistance of Sally Wilson.
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