Knowledge regarding the effects of hearing aids on speech acquisition is very limited in early-identified infants with hearing impairment (HI). The goal of this research is to improve language outcomes in infants with HI by addressing the lack of understanding of how early perception and production capacities emerge in infants with normal hearing (NH) and hearing impairment (HI). To attain this goal we will focus on understanding how the distributional properties of canonical babbling (CB) affect perceptual preferences for syllables in NH and HI infants. We will focus on CB as it is the first speech-like behavior affected by early amplification, it differentiates HI from NH infants, it forms the foundation for first words, and its delay predicts delays in vocabulary development. Our objectives are to (1) examine group differences (NH vs HI) in the development of perceptual preferences for canonical syllables at two time periods (Aim 1) and (2) examine whether infants'production of canonical syllables predicts their own perceptual preference for these syllables (Aim 2). Forty- eight infants (5- 15 months of age) with: (a) normal hearing sensitivity (n=24), and (b) mild-to-severe sensorineural hearing loss (n=24), will participate.
Aim 1 : Test the hypothesis that perceptual preference for the distributional characteristics of CB develops as a result of experience with CB. Our hypothesis predicts that compared to a pre-babbling baseline, NH infants'preferences will shift toward canonical syllables with coronal over labial onsets during the babbling period, whereas HI infants'preferences will shift towards canonical syllables with labial over coronal onsets. Our hypothesis predicts that compared to a pre-babbling baseline, both NH and HI infants'preferences will shift toward CV co-occurrences that are consistent with FCH over co-occurrences that are not consistent with FCH.
Aim 2 : Test the hypothesis that individual infants'production of canonical syllables predicts their own perceptual preference for syllable distributional properties during babbling. Our hypothesis predicts that the CV inventory of infants with NH will have a greater proportion of coronal consonants and that this will correlate with their perceptual preference. For infants with HI, we expect a greater proportion of labial consonants in their repertoire than coronals and this will correlate with a perceptual preference for labial onsets. Our hypothesis predicts that both NH and HI infants'inventories will have a greater proportion of CV co-occurrences that are consistent with FCH than that violate FCH, and this will correlate with the predicted preference for syllables that are consistent with FCH. Outcomes and Impact: When the aims of this research are achieved clinicians will be able to use CB production as an outcome measure of adequate auditory input during the pre-linguistic stage based on an evidence-based understanding of the relationship between audibility, what the infant is producing and perceiving in the earliest vocalizations impacted by amplification.
Data from this project will lead to improved understanding of the role auditory sensitivity plays in contributing to the emergence of perceptual preferences and production patterns during the canonical babbling period. This may lead to improved clinical outcome measures for infants identified early with hearing loss and will address the NIH need for evidence-based research to guide current clinical practice with infants with HI.
|Robertson, Susie; von Hapsburg, Deborah; Hay, Jessica S (2013) The effect of hearing loss on the perception of infant- and adult-directed speech. J Speech Lang Hear Res 56:1108-19|