Modifications in deaf children's vowel production: perceptual evidence

This study examined the perceived changes in vowel articulation by profoundly deaf children as a function of the method of teaching: with visual feedback provided by the Computer Vowel Trainer (CVT) vs conventional methods. The assessment carried out by experienced listeners consisted in marking the sounds heard on the vowel quadrilateral. It was found that changes in perception were feedback and age dependent: younger children taught with the CVT were perceived as displaying more mobility in articulation and they approximated more closely the target vowels than their control counterparts or older children. Progress was evident in particular for back and central vowels. Analysis of perceived discrepancies between target and judged vowels, too, suggested that visual feedback was beneficial: perception of experimental children's utterances showed a marked reduction in substitutions with central vowels, a characteristic pattern of deaf speech. Comparison of these findings with the results yielded by the judgement of the same items by naive listeners indicated broad agreement between the two categories of assessors. Results were discussed in terms of the perceptual and articulatory intervening variables with reference to the specific advantages and constraints imposed by evaluating vowel quality on the vowel plane.