Acoustic Differences Between Content and Function Words in Amyotrophic Lateral Sclerosis Studies describing acoustic characteristics of speech produced by individuals with dysarthria may help to explain intelligibility deficits for these speakers. One goal of the current study was to investigate the manner and extent to which nine speakers with mild to moderate dysarthria associated with amyotrophic lateral sclerosis (ALS) and nine ... Research Article
Research Article  |   June 01, 2000
Acoustic Differences Between Content and Function Words in Amyotrophic Lateral Sclerosis
 
Author Affiliations & Notes
  • Greg S. Turner
    Department of Communication Disorders Central Missouri State University Warrensburg
  • Kris Tjaden
    Department of Communicative Disorders and Sciences State University of New York at Buffalo
  • Contact author: Kris Tjaden, PhD, Department of Communicative Disorders and Sciences, SUNY at Buffalo, 122 Cary, 3435 Main Street, Buffalo, NY 14214-3005.
    Contact author: Kris Tjaden, PhD, Department of Communicative Disorders and Sciences, SUNY at Buffalo, 122 Cary, 3435 Main Street, Buffalo, NY 14214-3005.×
  • Corresponding author: Email: tjaden@acsu.buffalo.edu
Article Information
Speech, Voice & Prosodic Disorders / Hearing & Speech Perception / Acoustics / Special Populations / Speech, Voice & Prosody / Speech / Research Articles
Research Article   |   June 01, 2000
Acoustic Differences Between Content and Function Words in Amyotrophic Lateral Sclerosis
Journal of Speech, Language, and Hearing Research, June 2000, Vol. 43, 769-781. doi:10.1044/jslhr.4303.769
History: Received April 5, 1999 , Accepted November 12, 1999
 
Journal of Speech, Language, and Hearing Research, June 2000, Vol. 43, 769-781. doi:10.1044/jslhr.4303.769
History: Received April 5, 1999; Accepted November 12, 1999

Studies describing acoustic characteristics of speech produced by individuals with dysarthria may help to explain intelligibility deficits for these speakers. One goal of the current study was to investigate the manner and extent to which nine speakers with mild to moderate dysarthria associated with amyotrophic lateral sclerosis (ALS) and nine healthy speakers acoustically distinguished /i/, / æ/, /u/, and /α/ in content and function words. A further aim was to evaluate the relationship between impaired speech in ALS and the magnitude of acoustic differences for vowels in content and function words. Speakers read the Farm Passage at a comfortable or habitual rate. F1 and F2 midpoint frequencies were measured, and vowel space areas were calculated. Vowel durations also were measured. The magnitude of F1, F2, vowel space area, and duration differences for vowels in content and function words was not statistically different for speakers with ALS and healthy controls. In addition, with the exception of /i/ produced by some speakers with ALS, vowel duration tended to be shorter in function words. Average F1 and F2 values for function words also tended to be centralized relative to content words. Although vowel space area differences for the two speaker groups were not statistically significant, there was a tendency for the difference in vowel space area for content and function words to be smaller for speakers with ALS than for controls. Regression analyses further indicated that the magnitude of temporal differences for vowels in content and function words was a better predictor of impaired speech than the magnitude of spectral differences for vowels in content and function words. One clinical implication is that individuals with ALS may benefit from therapy techniques targeting temporal properties of the acoustic signal.

Acknowledgments
We would like to thank the patients and staff of the ALS Clinic at the University of Wisconsin Hospital and Clinics in Madison. We also thank Sherri Rusch for her laboratory assistance. Jan Charles-Luce, Joe Duffy, Chris Sapienza, Gary Weismer, and an anonymous reviewer made helpful comments on earlier drafts of the paper.
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