Multiple oppositions intervention: effective phonological treatment of two children with cleft lip and palate and severe speech sound disorder

The purpose of this study was to investigate if multiple oppositions intervention (MOI) generated widespread change in the phonological systems of two children with cleft lip and palate (CLP) and severe speech sound disorders (SSD). We treated two children (ages 5;4 and 5;6) with CLP and severe SSD using MOI for 24 and 29 sessions. We measured the percentage consonants correct (PCC) for target consonants and untreated consonants in non-treatment single words, as well as PCC for connected speech. Data points were collected in the baseline, intervention, and maintenance phase with post-tests conducted immediately after intervention and at 1, 3, 6 and 12 months. Two speech and language therapists (SLTs) unfamiliar with the children performed phonetic transcriptions, and we calculated intra- and inter-rater agreement. We graphed the data, and used permutation tests to analyse the probability that the observed increases in PCC were due to random chance. Both children experienced considerable improvements in PCC across all measures at the first post-test, supporting the impact of MOI on their entire phonological system. The PCC continued to increase during the maintenance phase. By the final post-test, the PCC in connected speech exceeded 90% for both children, reducing their SSD classification to mild. Our findings support that a phonological, contrastive intervention approach targeting multiple consonants simultaneously can create system-wide phonological change for children with CLP and severe SSD. Further research with more participants is needed to strengthen these findings.