Vowel Acoustics in Parkinson's Disease and Multiple Sclerosis: Comparison of Clear, Loud, and Slow Speaking Conditions PurposeThe impact of clear speech, increased vocal intensity, and rate reduction on acoustic characteristics of vowels was compared in speakers with Parkinson's disease (PD), speakers with multiple sclerosis (MS), and healthy controls.MethodSpeakers read sentences in habitual, clear, loud, and slow conditions. Variations in clarity, intensity, and rate were stimulated using ... Article
Article  |   October 01, 2013
Vowel Acoustics in Parkinson's Disease and Multiple Sclerosis: Comparison of Clear, Loud, and Slow Speaking Conditions
 
Author Affiliations & Notes
  • Kris Tjaden
    University at Buffalo, New York
  • Jennifer Lam
    University at Buffalo, New York
  • Greg Wilding
    University at Buffalo, New York
  • Correspondence to Kris Tjaden: tjaden@buffalo.edu
  • Editor: Jody Kreiman
    Editor: Jody Kreiman×
  • Associate Editor: Ewa Jacewicz
    Associate Editor: Ewa Jacewicz×
Article Information
Speech, Voice & Prosody / Speech
Article   |   October 01, 2013
Vowel Acoustics in Parkinson's Disease and Multiple Sclerosis: Comparison of Clear, Loud, and Slow Speaking Conditions
Journal of Speech, Language, and Hearing Research, October 2013, Vol. 56, 1485-1502. doi:10.1044/1092-4388(2013/12-0259)
History: Received August 16, 2012 , Revised December 6, 2012 , Accepted January 24, 2013
 
Journal of Speech, Language, and Hearing Research, October 2013, Vol. 56, 1485-1502. doi:10.1044/1092-4388(2013/12-0259)
History: Received August 16, 2012; Revised December 6, 2012; Accepted January 24, 2013
Web of Science® Times Cited: 17

PurposeThe impact of clear speech, increased vocal intensity, and rate reduction on acoustic characteristics of vowels was compared in speakers with Parkinson's disease (PD), speakers with multiple sclerosis (MS), and healthy controls.

MethodSpeakers read sentences in habitual, clear, loud, and slow conditions. Variations in clarity, intensity, and rate were stimulated using magnitude production. Formant frequency values for peripheral and nonperipheral vowels were obtained at 20%, 50%, and 80% of vowel duration to derive static and dynamic acoustic measures. Intensity and duration measures were obtained.

ResultsRate was maximally reduced in the slow condition, and vocal intensity was maximized in the loud condition. The clear condition also yielded a reduced articulatory rate and increased intensity, although less than for the slow or loud conditions. Overall, the clear condition had the most consistent impact on vowel spectral characteristics. Spectral and temporal distinctiveness for peripheral–nonperipheral vowel pairs was largely similar across conditions.

ConclusionsClear speech maximized peripheral and nonperipheral vowel space areas for speakers with PD and MS while also reducing rate and increasing vocal intensity. These results suggest that a speech style focused on increasing articulatory amplitude yields the most robust changes in vowel segmental articulation.

Acknowledgments
This research was supported by National Institute on Deafness and Other Communication Disorders Grant R01DC004689. Preliminary results were presented at the 15th Biennial Conference on Motor Speech Control in Savannah, GA, in March 2010. We acknowledge Joan Sussman for contributions to the sentence intelligibility measures and scaled estimates of speech severity as well as Christina Kuo for assistance with article preparation.
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