Lip Movement Exaggerations During Infant-Directed Speech PurposeAlthough a growing body of literature has indentified the positive effects of visual speech on speech and language learning, oral movements of infant-directed speech (IDS) have rarely been studied. This investigation used 3-dimensional motion capture technology to describe how mothers modify their lip movements when talking to their infants.MethodLip movements ... Article
Article  |   December 2010
Lip Movement Exaggerations During Infant-Directed Speech
 
Author Affiliations & Notes
  • Jordan R. Green
    University of Nebraska—Lincoln
  • Ignatius S. B. Nip
    San Diego State University, San Diego, CA
  • Erin M. Wilson
    Waisman Center, University of Wisconsin—Madison
  • Antje S. Mefferd
    Wichita State University, Wichita, KS
  • Yana Yunusova
    University of Toronto, Toronto, Ontario, Canada
  • Contact author: Jordan R. Green, Department of Special Education and Communication Disorders, University of Nebraska—Lincoln, 318 Barkley Center, Lincoln, NE 68583. E-mail: jgreen4@unl.edu.
  • © 2010 American Speech-Language-Hearing Association
Article Information
Speech, Voice & Prosody / Speech
Article   |   December 2010
Lip Movement Exaggerations During Infant-Directed Speech
Journal of Speech, Language, and Hearing Research, December 2010, Vol. 53, 1529-1542. doi:10.1044/1092-4388(2010/09-0005)
History: Received January 14, 2009 , Revised September 3, 2009 , Accepted March 24, 2010
 
Journal of Speech, Language, and Hearing Research, December 2010, Vol. 53, 1529-1542. doi:10.1044/1092-4388(2010/09-0005)
History: Received January 14, 2009; Revised September 3, 2009; Accepted March 24, 2010
Web of Science® Times Cited: 20

PurposeAlthough a growing body of literature has indentified the positive effects of visual speech on speech and language learning, oral movements of infant-directed speech (IDS) have rarely been studied. This investigation used 3-dimensional motion capture technology to describe how mothers modify their lip movements when talking to their infants.

MethodLip movements were recorded from 25 mothers as they spoke to their infants and other adults. Lip shapes were analyzed for differences across speaking conditions. The maximum fundamental frequency, duration, acoustic intensity, and first and second formant frequency of each vowel also were measured.

ResultsLip movements were significantly larger during IDS than during adult-directed speech, although the exaggerations were vowel specific. All of the vowels produced during IDS were characterized by an elevated vocal pitch and a slowed speaking rate when compared with vowels produced during adult-directed speech.

ConclusionThe pattern of lip-shape exaggerations did not provide support for the hypothesis that mothers produce exemplar visual models of vowels during IDS. Future work is required to determine whether the observed increases in vertical lip aperture engender visual and acoustic enhancements that facilitate the early learning of speech.

Acknowledgments
This work was supported by the National Institute on Deafness and Other Communication Disorders Grants R03DC004643 and R01DC006463. We thank Lacey LaBarge, Cynthia Didion, Cara Ullman, Lindsey Fairchild, Paige Mueller, and Kelli Raber for their assistance with data collection and analysis.
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