title: The shift in infant preferences for vowel duration and pitch contour between 6 and 10 months of age.
abstract: This study investigates the influence of the acoustic properties of vowels on 6- and 10-month-old infants' speech preferences. The shape of the contour (bell or monotonic) and the duration (normal or stretched) of vowels were manipulated in words containing the vowels /i/ and /u/, and presented to infants using a two-choice preference procedure. Experiment 1 examined contour shape: infants heard either normal-duration bell-shaped and monotonic contours, or the same two contours with stretched duration. The results show that 6-month-olds preferred bell to monotonic contours, whereas 10-month-olds preferred monotonic to bell contours. In Experiment 2, infants heard either normal-duration and stretched bell contours, or normal-duration and stretched monotonic contours. As in Experiment 1, infants showed age-specific preferences, with 6-month-olds preferring stretched vowels, and 10-month-olds preferring normal-duration vowels. Infants' attention to the acoustic qualities of vowels, and to speech in general, undergoes a dramatic transformation in the final months of the first year, a transformation that aligns with the emergence of other developmental milestones in speech perception.
authors.affiliation: MARCS Auditory Laboratories, University of Western Sydney, Sydney, NSW, Australia. c.kitamura@uws.edu.au
authors.forename: Christine
authors.initials: C
authors.lastname: Kitamura
authors.forename: Anna
authors.initials: A
authors.lastname: Notley
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000704:Analysis of Variance; D001288:Attention / Q000502:physiology*; D002657:Child Development / Q000502:physiology*; D005260:Female; D006801:Humans; D007223:Infant; D007802:Language; D008297:Male; D010700:Phonetics; D013018:Sound Spectrography / Q000379:methods; D013061:Speech Acoustics; D013067:Speech Perception / Q000502:physiology*; D014705:Verbal Behavior / Q000502:physiology*