Developmental Use of Vowel Duration as a Cue to Postvocalic Stop Consonant Voicing

This developmental study investigated vowel duration as a cue to postvocalic consonant voicing. Ten trials of six test words, spoken by 10,3-year-olds, 10 6-year-olds, and 10 adults, all with normal language and articulation and hearing, were analyzed. A significant interaction between the speaker's age and the voicing feature of the postvocalic consonant was found on measures of total vowel duration. The duration of vowels preceding voiceless stops was similar across ages, but vowel duration preceding voiced stops decreased sharply with age. In addition, decreased variability of vowel duration was observed with increasing age. Consideration is given to processes of exaggerated vowel lengthening and vowel shortening to describe children's acquisition of this voicing cue. The same subjects and stimulus words used in the production experiment were used in a previous perception experiment. Qualitative comparisons between the production and perception data revealed parallel refinement in the use of vowel duration as a function of age.