Differential vowel duration associated with children's word-final fricative deletion

This study assessed whether 3 children, 5 to 6 years old, who deleted word-final fricatives preserve the voicing contrast for those fricatives by producing dif ferential duration of the preceding vowel. The children's CV syllable productions were compared to their CV(C) syllable productions in which the final consonant was intended but actually deleted. Analysis indicated that all 3 children exhibited significantly longer vowel duration, in CV syllables than in CV(C) syllables. This differential duration of the preceding vowel was shown in both isolation and carrier phrase conditions. Of the 3 children 2 preserved the voicing contrast by showing significantly longer vowels preceding voiced consonants as compared to voiceless consonants. One child did this in both isolation and carrier phrase conditions and the other child did this in isolation only. All 3 children manipulated vowel duration to signify the linguis tic contrast, therefore these findings support a linguistic perspective of speech development which focuses on the acquisition and knowledge of the linguistic rules of the language. In addition, the large amount of variability in vowel duration for CV and CV(C) syllables and the marked variability in performance across children support a biological view of a developing vocal tract undergoing structural and physiological changes.