Vowel systems of normally developing and phonologically disordered children.

Available literature on the acquisition of vowels in normally developing and phonologically disordered subjects is reviewed and detailed case studies of the vowel productions of two phonologically disordered subjects are presented. The findings reveal parallels between the accuracy levels for disordered subjects and order of mastery in younger normal children. In both populations, corner vowels are produced accurately before non-corner vowels. Unstressed vowels were found to be problematic for children with phonological disorders.