Purpose: The speech of some children does not follow a typical normalization trajectory, and they develop speech sound disorders (SSD). This study investigated predictive correlates of speech sound normalization in children who were at risk of SSD.
Method: A prospective population cohort study of 845 Cantonese-speaking preschoolers was conducted over 2.5 years to examine (a) children who resolved nonadult realizations of consonants (normalized) and (b) those who had persisting speech sound difficulties (did not normalize). From these 845, a sample of 82 participants characterized as having SSD (1.25 SDs below the mean in a standardized speech assessment, with a delay in initial consonant acquisition or with one or more atypical errors) was followed for 2 years at 6-month intervals or until the completion of their initial consonant inventory. Data from 43 children who did not receive speech-language pathology services were analyzed with survival analysis to model time to normalization while controlling for covariates. The target event (outcome) was the completion of their initial consonant inventory.
Results: Under the no-intervention condition, the estimated median time to normalization was 6.59 years of age. Children who were more likely to normalize or normalized in a shorter time were stimulable to all errors and more intelligible as rated by caregivers using the Intelligibility in Context Scale. Those who showed atypical error patterns did not necessarily take longer to normalize. Similarly, expressive language ability was not significantly associated with speech normalization.
Conclusions: Stimulability and intelligibility were more useful prognostic factors of speech normalization when compared to (a)typicality of error patterns and expressive language ability. Children with low intelligibility and poor stimulability should be prioritized for speech-language pathology services given that their speech errors are less likely to resolve naturally.