Phonetic modification of vowel space in storybook speech to infants up to 2 years of age

Evamarie B. Burnham, Elizabeth A. Wieland, Maria V. Kondaurova, J. Devin McAuley, Tonya R. Bergeson, Laura C. Dilley

Research output: Contribution to journalArticle

12 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)241-253
Number of pages13
JournalJournal of Speech, Language, and Hearing Research
Issue number2
StatePublished - Apr 1 2015

ASJC Scopus subject areas

  • Language and Linguistics
  • Linguistics and Language
  • Speech and Hearing

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