Talker Differences in Clear and Conversational Speech: Acoustic Characteristics of Vowels Purpose To determine the specific acoustic changes that underlie improved vowel intelligibility in clear speech. Method Seven acoustic metrics were measured for conversational and clear vowels produced by 12 talkers—6 who previously were found (S. H. Ferguson, 2004) to produce a large clear speech vowel intelligibility effect for ... Research Article
Research Article  |   October 01, 2007
Talker Differences in Clear and Conversational Speech: Acoustic Characteristics of Vowels
 
Author Affiliations & Notes
  • Sarah Hargus Ferguson
    Indiana University, Bloomington
  • Diane Kewley-Port
    Indiana University, Bloomington
  • Contact author: Sarah Hargus Ferguson, Department of Speech-Language-Hearing: Sciences and Disorders, University of Kansas, Dole Center, 1000 Sunnyside Avenue, Room 3001, Lawrence, KS 66045-7555. E-mail: safergus@ku.edu.
Article Information
Normal Language Processing / Speech, Voice & Prosody / Speech / Research Articles
Research Article   |   October 01, 2007
Talker Differences in Clear and Conversational Speech: Acoustic Characteristics of Vowels
Journal of Speech, Language, and Hearing Research, October 2007, Vol. 50, 1241-1255. doi:10.1044/1092-4388(2007/087)
History: Received August 28, 2006 , Accepted March 7, 2007
 
Journal of Speech, Language, and Hearing Research, October 2007, Vol. 50, 1241-1255. doi:10.1044/1092-4388(2007/087)
History: Received August 28, 2006; Accepted March 7, 2007
Web of Science® Times Cited: 57

Purpose To determine the specific acoustic changes that underlie improved vowel intelligibility in clear speech.

Method Seven acoustic metrics were measured for conversational and clear vowels produced by 12 talkers—6 who previously were found (S. H. Ferguson, 2004) to produce a large clear speech vowel intelligibility effect for listeners with normal hearing identifying vowels in background noise (the big benefit talkers), and 6 who produced no clear speech vowel intelligibility benefit (the no benefit talkers).

Results For vowel duration and for certain measures of the overall acoustic vowel space, the change from conversational to clear speech was significantly greater for big benefit talkers than for no benefit talkers. For measures of formant dynamics, in contrast, the clear speech effect was similar for the 2 groups.

Conclusion These results suggest that acoustic vowel space expansion and large vowel duration increases improve vowel intelligibility. In contrast, changing the dynamic characteristics of vowels seems not to contribute to improved clear speech vowel intelligibility. However, talker variability suggested that improved vowel intelligibility can be achieved using a variety of clear speech strategies, including some apparently not measured here.

Acknowledgments
This research was conducted as part of a doctoral dissertation completed at Indiana University and was supported by Grant NIHDCD-02229 from the National Institute on Deafness and Other Communication Disorders. We gratefully acknowledge Kenneth de Jong, Larry E. Humes, David B. Pisoni, and Charles S. Watson for their contributions to this research.
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