Regional dialect variation in the vowel systems of typically developing children.

PURPOSE To investigate regional dialect variation in the vowel systems of typically developing 8- to 12-year-old children. METHOD Thirteen vowels in isolated h_d words were produced by 94 children and 93 adults (males and females). All participants spoke American English and were born and raised in 1 of 3 distinct dialect regions in the United States: western North Carolina (Southern dialect), central Ohio (Midland dialect), and southeastern Wisconsin (Northern Midwestern dialect). Acoustic analysis included formant frequencies (F1 and F2) measured at 5 equidistant time points in a vowel and formant movement (trajectory length). RESULTS Children's productions showed many dialect-specific features comparable to those in adult speakers, both in terms of vowel dispersion patterns and formant movement. Different features were also found, including systemic vowel changes, significant monophthongization of selected vowels, and greater formant movement in diphthongs. CONCLUSIONS The acoustic results provide evidence for regional distinctiveness in children's vowel systems. Children acquire not only the systemic relations among vowels but also their dialect-specific patterns of formant dynamics. Directing attention to the regional variation in the production of American English vowels, this work may prove helpful in better understanding and interpreting the development of vowel categories and vowel systems in children.