The Effect of Fundamental Frequency on the Intelligibility of Speech With Flattened Intonation Contours Purpose To examine the effect of fundamental frequency (F0) on the intelligibility of speech with flattened F0 contours in noise. Method Participants listened to sentences produced by 2 female talkers in white noise. The listening conditions included the unmodified original sentences and sentences with resynthesized F0 that reflected ... Research Article
Research Article  |   November 01, 2008
The Effect of Fundamental Frequency on the Intelligibility of Speech With Flattened Intonation Contours
 
Author Affiliations & Notes
  • Peter J. Watson
    University of Minnesota, Minneapolis
  • Robert S. Schlauch
    University of Minnesota, Minneapolis
  • Contact author: Peter J. Watson, Department of Speech-Language-Hearing Sciences, 164 Pillsbury Drive SE, Shevlin 115, University of Minnesota, Minneapolis, MN 55455. E-mail: pjwatson@umn.edu.
Article Information
Speech, Voice & Prosodic Disorders / Speech, Voice & Prosody / Research Articles
Research Article   |   November 01, 2008
The Effect of Fundamental Frequency on the Intelligibility of Speech With Flattened Intonation Contours
American Journal of Speech-Language Pathology, November 2008, Vol. 17, 348-355. doi:10.1044/1058-0360(2008/07-0048)
History: Received June 27, 2007 , Accepted February 7, 2008
 
American Journal of Speech-Language Pathology, November 2008, Vol. 17, 348-355. doi:10.1044/1058-0360(2008/07-0048)
History: Received June 27, 2007; Accepted February 7, 2008
Web of Science® Times Cited: 23

Purpose To examine the effect of fundamental frequency (F0) on the intelligibility of speech with flattened F0 contours in noise.

Method Participants listened to sentences produced by 2 female talkers in white noise. The listening conditions included the unmodified original sentences and sentences with resynthesized F0 that reflected the average low F0, the median F0, and the average high F0 of each talker’s productions.

Results The sentences with flattened F0 contours yielded poorer intelligibility than the unmodified ones, but the sentences with flattened F0 did not produce equivalent performance. The sentences with F0 contours flattened at the average low F0 yielded better performance than sentences at the median F0. The sentences with F0 flattened at the average high F0 yielded poorer performance than the sentences flattened at the median F0.

Conclusions F0 height accounted for only a small amount of the drop in speech understanding in speech with a flattened F0 in healthy talkers. Although this study used healthy talkers, the findings suggest that clinicians should focus on having clients produce speech with naturally varying F0; F0 height is a secondary factor in the drop in intelligibility seen in monotone speech for female talkers.

Acknowledgments
We are grateful to Edward Carney for assistance with the data analysis and interpretation and providing helpful comments on previous versions of this article. We are also grateful to Christophe Micheyl for sharing with us Matlab routines for the implementation of Glasberg and Moore’s (1990)  auditory model. We wish also to thank Lisa LaMora and Elin Roverud for their help with data collection.
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