Durational and spectral differences in American English vowels: dialect variation within and across regions.

Spectral differences among varieties of American English have been widely studied, typically recognizing three major regionally diagnostic vowel shift patterns [Labov, Ash, and Boberg (2006). The Atlas of North American English: Phonetics, Phonology and Sound Change (De Gruyter, Berlin)]. Durational variability across dialects, on the other hand, has received relatively little attention.