Vowel targeted intervention for children with persisting speech difficulties: Impact on intelligibility

Compared to the treatment of consonant segments, the treatment of vowels is infrequently described in the literature on children's speech difficulties. Vowel difficulties occur less frequently than those with consonants but may have significant impact on intelligibility. In order to evaluate the effectiveness of vowel targeted intervention (VTI) with two 10-year-old children with severe and persisting speech difficulties measures of (a) percentage vowels correct and (b) intelligibility outcomes by peer group listeners were used. Assessment of vowel production was used to design and carry out intervention for each child, the success of which was measured in two ways: comparing (a) percentage of vowels correct before and after the intervention, (b) the percentage of pre- vs. post-intervention utterances understood by a group of typical peer listeners (aged 9 to 11 years). Pre- and post-intervention speech samples (comprising single words, imitated sentences and spontaneous speech) were edited onto a CD for these listeners, who were asked to write down what had been said. The two children with speech difficulties made significant improvement in vowel production as measured by the percentage of vowels correct. The listeners perceived more productions accurately post-intervention than pre-intervention. There was also a reduction in the range of the listeners' misperceptions of target words. VTI was effective in terms of both increasing PVC and intelligibility outcomes as judged by peer group listeners. It is not more complicated to carry out VTI than consonant targeted intervention; this should be considered more often when planning therapy for children where vowels are affected.