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

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.

Early Phonological Predictors of Toddler Language Outcomes.

PURPOSE: Several studies have explored relationships between children's early phonological development and later language performance. This literature has included a more recent focus on the potential for early phonological profiles to predict later language outcomes. METHODS: The present study longitudinally examined the nature of phonetic inventories and syllable structure patterns of 48 typically developing children at 7, 11, and 18 months, and related them to expressive language outcomes at 2 years of age. RESULTS: Findings provide evidence that as early as 11 months, phonetic inventory and mean syllable structure level are related to 24-month expressive language outcomes, including mean length of utterance and vocabulary diversity in spontaneous language samples, and parent-reported vocabulary scores. Consonant inventories in particular differed at 11 and 18 months for 2-year-olds with lower versus higher language skills. CONCLUSION: Limited inventories and syllable repertoires may add to risk profiles for later language delays.

An exploration of the role of executive functions in preschoolers' phonological development.

There is limited yet compelling evidence that domain-general processes may contribute to speech sound change. This study explored whether executive functions contribute to the achievement of adult-like speech production. Children who are 4 to 5 years old, 42 with high-average speech production skills, 11 with low-average and nine with speech sound disorder (SSD), participated in a battery of executive function and speech production tasks. Performance accuracy was compared across groups and also correlated with speech sound accuracy from a single-word naming task. Children with SSD demonstrated poorer performance than other groups on forward digit span, whereas children with low-average speech skills underperformed their peers on the Flexible Item Selection Task (FIST). These preliminary results suggest that children with speech errors may have less mature working memory than peers who have mastered phonological targets earlier in development.

Non-word repetition in 2-year-olds: Replication of an adapted paradigm and a useful methodological extension.

Accurate non-word repetition (NWR) has been largely attributed to phonological memory, although the task involves other processes including speech production, which may confound results in toddlers with developing speech production abilities. This study is based on Hoff, Core and Bridges' adapted NWR task, which includes a real-word repetition (RWR) condition. We tested 86 typically developing 2-year-olds and found relationships between NWR and both receptive and expressive vocabulary using a novel measure that controls for speech production by comparing contextually matched targets in RWR. Post hoc analyses demonstrated the influence of lexical and sublexical factors in repetition tasks. Overall, results illustrate the importance of controlling for speech production differences in young children and support a useful methodological approach for testing NWR.

Rate and phonological variation in preschool children: effects of modeling and directed influence.

PURPOSE: To explore the effect of modeling and explicit elicitation of slow and accurately produced speech in typically developing preschool children. Optional phonological reductions (e.g., deleted final stops) and changes in speech rate were examined in response to an adult conversational speaker's speech style. METHOD: Forty 3- and 4-year-olds (20 each) were tested in 3 tasks: (a) immediate repetition of a model, (b) spontaneous speech, and (c) directed speech style (cueing to correct "sloppy" speech). In Task 1, half of each group heard fast and hypoarticulated versus slow and hyperarticulated speech for a between-group response-to-model comparison. Tasks 2 and 3 were compared within subjects. RESULTS: Task 1 demonstrated that both age groups aligned with the speaker's rate and phonological variants usage when repeating a model. Tasks 2 and 3 revealed that 4-year-olds varied phonological reduction patterns according to the task demands, whereas 3-year-olds maintained consistent patterns of usage. In addition, neither group successfully realigned with the rapid speech rate in Task 3. CONCLUSIONS: These results contribute to an evidence base supporting the practice of modeling slow and clear speech to children with various production disorders. Further research is needed to explore the cognitive-linguistic processes underlying alignment before findings are applied to clinical populations.