Modified Spectral Tilt Affects Older, but Not Younger, Infants' Native-Language Fricative Discrimination PurposeIt is important to ensure that hearing aid fitting strategies for infants take into account the infant’s developing speech perception system. As a way of exploring this issue, this study examined how 6- and 9-month-olds with normal hearing perceive native-language speech in which the natural spectral shape was altered to ... Article
Article  |   April 01, 2011
Modified Spectral Tilt Affects Older, but Not Younger, Infants' Native-Language Fricative Discrimination
 
Author Affiliations & Notes
  • Elizabeth Francis Beach
    MARCS Auditory Laboratories, University of Western Sydney, New South Wales, Australia
    MARCS Auditory Laboratories, University of Western Sydney, New South Wales, Australia
  • Christine Kitamura
    MARCS Auditory Laboratories, University of Western Sydney, New South Wales, Australia
    MARCS Auditory Laboratories, University of Western Sydney, New South Wales, Australia
  • Correspondence to Elizabeth Beach: elizabeth.beach@nal.gov.au
  • Editor: Robert S. Schlauch
    Editor: Robert S. Schlauch×
  • Associate Editor: Kathryn Arehart
    Associate Editor: Kathryn Arehart×
Article Information
Speech, Voice & Prosody / Hearing
Article   |   April 01, 2011
Modified Spectral Tilt Affects Older, but Not Younger, Infants' Native-Language Fricative Discrimination
Journal of Speech, Language, and Hearing Research, April 2011, Vol. 54, 658-667. doi:10.1044/1092-4388(2010/08-0177)
History: Received August 27, 2008 , Revised June 22, 2009 , Accepted August 8, 2010
 
Journal of Speech, Language, and Hearing Research, April 2011, Vol. 54, 658-667. doi:10.1044/1092-4388(2010/08-0177)
History: Received August 27, 2008; Revised June 22, 2009; Accepted August 8, 2010
Web of Science® Times Cited: 2

PurposeIt is important to ensure that hearing aid fitting strategies for infants take into account the infant’s developing speech perception system. As a way of exploring this issue, this study examined how 6- and 9-month-olds with normal hearing perceive native-language speech in which the natural spectral shape was altered to emphasize either high-frequency (positive spectral tilt) or low-frequency (negative spectral tilt) information.

MethodDiscrimination was tested using a visual habituation procedure. Forty-eight 6-month-olds and forty-eight 9-month-olds were presented with a fricative contrast, /f/–/s/, in 1 of 3 conditions: (a) as unmodified speech; (b) with a −6 dB/octave tilt; or (c) with a +6 dB/octave tilt.

ResultsSix-month-olds showed evidence of discriminating /f/–/s/ in all 3 conditions, but 9-month-olds showed such evidence only in the unmodified condition.

ConclusionsThe findings suggest that the perceptual reorganization that emerges for consonants at the end of the first year affects 9-month-olds' discrimination of native speech sounds. Perceptual reorganization is usually indexed by a decline in the ability to discriminate nonnative speech sounds. In this study, 6-month-olds demonstrated an acoustic-based sensitivity to both modified and unmodified native speech sounds, but 9-month-olds were most sensitive to the unmodified speech sounds that adhered to the native spectral profile.

Acknowledgments
This research was funded by Australian Research Council Grant DP 0559134, awarded to the second author. We thank Harvey Dillon and Teresa Ching from the National Acoustic Laboratories, who assisted with the speech stimuli; Robin Panneton and Scott Johnson, who allowed us to use their visual stimuli; and Anna Notley, Suzy Bicanic, and Cat Grimsgaard, who assisted with recruitment and testing of babies. Special thanks to all the babies and their parents who participated in our study.
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