Modelling category goodness judgments in children with residual sound errors.

This study investigates category goodness judgments of /r/ in adults and children with and without residual speech errors (RSEs) using natural speech stimuli. Thirty adults, 38 children with RSE (ages 7-16) and 35 age-matched typically developing (TD) children provided category goodness judgments on whole words, recorded from 27 child speakers, with /r/ in various phonetic environments. The salient acoustic property of /r/ - the lowered third formant (F3) - was normalized in two ways. A logistic mixed-effect model quantified the relationships between listeners' responses and the third formant frequency, vowel context and clinical group status. Goodness judgments from the adult group showed a statistically significant interaction with the F3 parameter when compared to both child groups (p < 0.001) using both normalization methods. The RSE group did not differ significantly from the TD group in judgments of /r/. All listeners were significantly more likely to judge /r/ as correct in a front-vowel context. Our results suggest that normalized /r/ F3 is a statistically significant predictor of category goodness judgments for both adults and children, but children do not appear to make adult-like judgments. Category goodness judgments do not have a clear relationship with /r/ production abilities in children with RSE. These findings may have implications for clinical activities that include category goodness judgments in natural speech, especially for recorded productions.

Fricatives at 18 months as a measure for predicting vocabulary and grammar at 24 and 30 months.

PURPOSE: Language develops at variable rates in young children, yet markers for different developmental trajectories, have not been identified. Production of fricatives in words may be one marker because they are later developing sounds and contribute to syntactic production. We examined whether children who produced fricatives in words by 18 months had better vocabulary and grammar scores at 18, 24, and 30 months than children who did not. METHOD: The expressive language skills of 37 toddlers who did and did not produce fricatives in words by 18 months of age were compared at 18, 24 and 30 months of age. RESULTS: Expressive vocabulary scores and the use of grammatical markers were significantly better for children who produced fricatives by 18 months than for those who did not. This effect was consistent across scores at 18, 24, and 30 months. The total number of consonants and total number of fricatives produced at 18 months did not significantly predict expressive vocabulary scores. CONCLUSIONS: Because the children who produced fricatives by 18 months demonstrated better expressive language skills than their peers who did not produce fricatives by 18 months, the early production of fricatives by toddlers may be a marker of a faster expressive language developmental trajectory. LEARNING OUTCOMES: Readers will: (1) describe the relationship between early phonological development and early expressive lexical development, (2) describe the role of perceptual and motor development in speech sound the acquisition, and (3) describe the potential relationship between the production of fricatives and expressive language development.