Phonetic Modification of Vowel Space in Storybook Speech to Infants up to 2 Years of Age Purpose A large body of literature has indicated vowel space area expansion in infant-directed (ID) speech compared with adult-directed (AD) speech, which may promote language acquisition. The current study tested whether this expansion occurs in storybook speech read to infants at various points during their first 2 years of life. ... Research Article
Research Article  |   April 01, 2015
Phonetic Modification of Vowel Space in Storybook Speech to Infants up to 2 Years of Age
 
Author Affiliations & Notes
  • Evamarie B. Burnham
    Michigan State University, East Lansing
  • Elizabeth A. Wieland
    Michigan State University, East Lansing
  • Maria V. Kondaurova
    Indiana University School of Medicine, Indianapolis
  • J. Devin McAuley
    Michigan State University, East Lansing
  • Tonya R. Bergeson
    Indiana University School of Medicine, Indianapolis
  • Laura C. Dilley
    Michigan State University, East Lansing
  • Disclosure: The authors have declared that no competing interests existed at the time of publication.
    Disclosure: The authors have declared that no competing interests existed at the time of publication.×
  • Correspondence to Laura C. Dilley: ldilley@msu.edu
  • Editor: Jody Kreiman
    Editor: Jody Kreiman×
  • Associate Editor: Megha Sundara
    Associate Editor: Megha Sundara×
Article Information
Speech, Voice & Prosodic Disorders / Voice Disorders / Normal Language Processing / Speech, Voice & Prosody / Speech / Research Articles
Research Article   |   April 01, 2015
Phonetic Modification of Vowel Space in Storybook Speech to Infants up to 2 Years of Age
Journal of Speech, Language, and Hearing Research, April 2015, Vol. 58, 241-253. doi:10.1044/2015_JSLHR-S-13-0205
History: Received August 1, 2013 , Revised May 2, 2014 , Accepted December 27, 2014
 
Journal of Speech, Language, and Hearing Research, April 2015, Vol. 58, 241-253. doi:10.1044/2015_JSLHR-S-13-0205
History: Received August 1, 2013; Revised May 2, 2014; Accepted December 27, 2014
Web of Science® Times Cited: 2

Purpose A large body of literature has indicated vowel space area expansion in infant-directed (ID) speech compared with adult-directed (AD) speech, which may promote language acquisition. The current study tested whether this expansion occurs in storybook speech read to infants at various points during their first 2 years of life.

Method In 2 studies, mothers read a storybook containing target vowels in ID and AD speech conditions. Study 1 was longitudinal, with 11 mothers recorded when their infants were 3, 6, and 9 months old. Study 2 was cross-sectional, with 48 mothers recorded when their infants were 3, 9, 13, or 20 months old (n = 12 per group). The 1st and 2nd formants of vowels /i/, /ɑ/, and /u/ were measured, and vowel space area and dispersion were calculated.

Results Across both studies, 1st and/or 2nd formant frequencies shifted systematically for /i/ and /u/ vowels in ID compared with AD speech. No difference in vowel space area or dispersion was found.

Conclusions The results suggest that a variety of communication and situational factors may affect phonetic modifications in ID speech, but that vowel space characteristics in speech to infants stay consistent across the first 2 years of life.

Acknowledgments
This research was supported by National Institute on Deafness and Other Communication Disorders Grant R01 DC 008581, awarded to T. R. Bergeson. We thank members of the RAP Lab at Bowling Green State University and the MSU Speech-Perception Production Lab at Michigan State University for helping in the analysis of the speech tokens. We also would like to thank Shannon Aronjo, Erin Crask, Kabreea Dunn, Carrie Hansel, Heidi Neuburger, Brittnie Ostler, Crystal Spann, Julie Wescliff, Heather Winegard, and Neil Wright for their help in preparing materials and recording and analyzing mothers' speech.
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