Treatment effects on cluster development in the speech of 4-year-old children with speech disorder

Purpose: This study examined the effectiveness of two differing interventions to improve the consonant cluster production in six children aged 4-5 years with concomitant speech sound disorder and expressive language difficulty. Method: Participants were selected for the study based on a high incidence of consonant clusters errors in their speech production. All participants had at least 75% of their cluster production attempts in error in their initial speech sample. The participants were randomly assigned to receive 24 hours of either a phonological awareness intervention with integrated speech targets (Gillon & Moriarty, 2005), or a morphosyntax intervention which alternated therapy sessions for language and speech targets (Haskill, Tyler, & Tolbert, 2001) Each intervention was administered in two blocks of 6 weeks separated by a 6-week therapy break. Hour-long small group intervention sessions were attended twice weekly by all participants. Consonant cluster productions were assessed using speech probes and standardised speech assessments. These were administered pre-intervention, post-intervention, and at follow-up 3 months post-intervention. These measures were compared to identify any improvement in (a) word-initial cluster accuracy as a result of /s/ clusters being targeted in the phonological awareness intervention;(b) word-final cluster accuracy as a result of word-final morphemes being targeted in the morphosyntax intervention; and (c) cluster element accuracy as a result of improved production of the phonemes as singletons. Results: The data supported the hypotheses that targeting word-initial clusters in the phonological awareness intervention would lead to improvements in accuracy for target /s/ clusters, non-target /s/ clusters and singleton fricatives. Improvements in production of /s/ clusters, singleton fricatives, and untreated consonant + liquid clusters were significant for all participants in this intervention type. The improvement for word initial /s/ clusters was greater than for the treatment group who received morphosyntax intervention. The data was less convincing for the hypothesis that word-final cluster production would improve following intervention for word-final morphemes in the morphosyntax intervention. Although there was improvement in word-final production for two of the participants in this group, there were similar or greater improvements seen for the children who received phonological awareness intervention in which word-final clusters were not targeted. The data supported the final hypothesis that improved production of singletons following speech intervention for these phonemes would result in improved accuracy for the phonemes when attempted in the context of clusters. All participants had improved accuracy of cluster elements that had been singleton targets during intervention. Conclusion: The data showed that the Phonological Awareness intervention led to significant improvement in production of the target /s/ clusters, and generalised to increased accuracy for production of singleton fricatives, non-target /s/ clusters, and untreated consonant + liquid clusters. The Morphosyntax intervention resulted in less consistent improvement in production for target word-final clusters. In this programme, word-final clusters were implicitly treated through language intervention for word-final morphemes. The data indicates that improvement in consonant cluster production is facilitated when using explicit teaching methods to introduce and practice consonant clusters during intervention with children with speech sound disorder