The interaction of vowel length and speech style in an Arapaho speech corpus

Cross-linguistically, vowel length contrasts may involve changes in vowel quality. In a different but more gradient way, speech style influences vowel articulation. While both alter vowel acoustics, it remains unclear whether both are byproducts of general processes of vowel undershoot or reflect a modification of articulatory gestures independent of durational constraints. This study investigates the influence of distinctive vowel length and speech style on vowel production in an Arapaho speech corpus. We find that length contributes most strongly to differences in duration and vowel quality, where short vowels are more centralized and long vowels more peripheral. However, the effect of speech style is asymmetrical: long vowels undergo greater durational compression in narrative speech than short vowels do, but the latter undergo greater changes in quality. These findings support the view that speech style produces not only patterns of vowel undershoot, but also active changes in vowel articulation.