The relationship between duration and spectral position in white southern US speech

Abstract

Previous research on regional differences in vowel quality and duration found that white Southern speakers make less of a distinction between high and mid tense-lax vowel pairs in both quality and duration than speakers from other regions (Kendall et al., 2014). However, the effect of duration on vowel quality in Southern speech has not been explored to the same degree. This study examines duration, vowel quality (in F1-F2 space), and their relationship. Data come from 80 h of self-recorded and interview speech from 17 white Southern natives with varying degrees of the Southern Vowel Shift (SVS). Measurements for F1 and F2 were extracted at vowel nucleus (25% duration) for the /e/-/ɛ/ and /i/-/ɪ/ pairs both implicated in the SVS. Formants were Lobanov-normalized and both duration and vowel quality were examined with mixed-effects linear regression. Results show that most speakers maintain a durational distinction between tense-lax pairs, but the effect of duration on vowel quality varies greatly from speaker to speaker. Those speakers who exhibit higher degrees of SVS shift show individual slopes for duration in the opposite direction than less-Southern counterparts. First, these results demonstrate that controlling for individual differences in duration is important for properly analyzing Southern speech corpora. Second, they suggest that duration, vowel quality, and their relationship all play a role in regional distinction.