Acoustic-Lexical Characteristics of Child-Directed Speech Between 7 and 24 Months and Their Impact on Toddlers' Phonological Processing.

Margaret Cychosz,Rochelle S Newman,Catherine Torrington Eaton,Jan R Edwards,Nan Bernstein Ratner

doi:10.3389/fpsyg.2021.712647

Abstract

Speech-language input from adult caregivers is a strong predictor of children's developmental outcomes. But the properties of this child-directed speech are not static over the first months or years of a child's life. This study assesses a large cohort of children and caregivers (n = 84) at 7, 10, 18, and 24 months to document (1) how a battery of phonetic, phonological, and lexical characteristics of child-directed speech changes in the first 2 years of life and (2) how input at these different stages predicts toddlers' phonological processing and vocabulary size at 2 years. Results show that most measures of child-directed speech do change as children age, and certain characteristics, like hyperarticulation, actually peak at 24 months. For language outcomes, children's phonological processing benefited from exposure to longer (in phonemes) words, more diverse word types, and enhanced coarticulation in their input. It is proposed that longer words in the input may stimulate children's phonological working memory development, while heightened coarticulation simultaneously introduces important sublexical cues and exposes them to challenging, naturalistic speech, leading to overall stronger phonological processing outcomes.

Highlights

The speech and language that children hear early in life is a strong predictor of their linguistic outcomes (Hart and Risley, 1995; Rowe, 2008; Huttenlocher et al, 2010)
Child-Directed Speech and Phonological Processing their changes over development, have been documented (Liu et al, 2009; Ko, 2012; Cristia, 2013; Hartman et al, 2017; Kalashnikova and Burnham, 2018), less is known about the phonological-lexical characteristics of child-directed speech (CDS)
We evaluated the role of each potential phono-lexical parameter: Word Frequency, Word Length, Phonological Neighborhood Density, Phonotactic Probability, Number of Word Types, Number of Word Tokens, MEAN AVERAGE TYPE:TOKEN RATIO (MATTR), and Type:Token Ratio (TTR)

Summary

Introduction

The speech and language that children hear early in life is a strong predictor of their linguistic outcomes (Hart and Risley, 1995; Rowe, 2008; Huttenlocher et al, 2010). Child-Directed Speech and Phonological Processing their changes over development, have been documented (Liu et al, 2009; Ko, 2012; Cristia, 2013; Hartman et al, 2017; Kalashnikova and Burnham, 2018), less is known about the phonological-lexical characteristics of CDS. Previous observations about the effects of acoustic properties of CDS on children’s speech-language outcomes could instead be attributable to lexical properties of the input. It is essential that we understand not if input matters for children’s phonological processing, and how and when

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