A longitudinal study of infants' early speech production and later letter identification.

Kelly Farquharson,Lesa Hoffman,Tiffany P Hogan,Jun Wang,Jordan R Green,Kimber F Green

doi:10.1371/journal.pone.0204006

Abstract

Letter identification is an early metric of reading ability that can be reliability tested before a child can decode words. We test the hypothesis that early speech production will be associated with children’s later letter identification. We examined longitudinal growth in early speech production in 9 typically developing children across eight occasions, every 3 months from 9 months to 30 months. At each occasion, participants and their caregivers engaged in a speech sample in a research lab. This speech sample was transcribed for a variety of vocalizations, which were then transformed to calculate consonant-vowel ratio. Consonant-vowel ratio is a measure of phonetic complexity in speech production. At the age of 72 months, children’s letter knowledge was measured. A multilevel model including fixed quadratic age change and a random intercept was estimated using letter identification as a predictor of the growth in early speech production from 9–30 months, measured by the outcome of consonant-vowel ratio. Results revealed that the relation between early speech production and letter identification differed over time. For each additional letter that a child identified, their consonant-vowel ratio at the age of 9 months increased. As such, these results confirmed our hypothesis: more robust early speech production is associated with more accurate letter identification.

Highlights

Language skills such as phonological awareness [1, 2, 3, 4], vocabulary [5, 6, 7, 8], syntax [9] and letter knowledge [10, 11, 12] are predictive of reading performance
The significance of random effects was evaluated through −2LL differences between nested models, whereas the significance of fixed effects was evaluated via univariate and multivariate Wald tests using Kenward–Roger denominator degrees of freedom
The results of our study support a connection between growth in early speech production abilities and later letter identification skills, which is a strong predictor of later word reading skills [10, 11]

Summary

Introduction

Language skills such as phonological awareness [1, 2, 3, 4], vocabulary [5, 6, 7, 8], syntax [9] and letter knowledge [10, 11, 12] are predictive of reading performance. Children with weak early language skills are at risk for reading impairments. These ‘early’ language skills are not measured reliably until 3–5 years of age [13]. We hypothesize that an earlier language ability, speech production, measured in infancy and toddlerhood will be associated with later letter knowledge.

Methods

Results

Discussion

Conclusion