Articulatory adaptations to the effect of nasality on vowel formants in Xinfeng Tieshikou Hakka

Articulatory compensation for mismatches between expected and perceived formants appears to be a fundamental component of speech production. We pursue the hypothesis that this component of speech production accounts for observed differences in articulation between oral and nasal vowel pairs in natural language production. The empirical focus is Xinfeng Tieshikou Hakka (XTH). We report acoustic analyses of three oral-nasal vowel pairs, [i]-[ĩ], [e]-[ẽ], [a]-[ã], from eight speakers as well as electromagnetic articulography of two oral-nasal vowel pairs, [e]-[ẽ], [a]-[ã], from one of these speakers. Building on past work, which has successfully isolated the independent influence of velopharyngeal (VP) coupling on vowel formants, we evaluate whether there is articulatory adaptation that conspires to maintain similar formants across oral and nasal vowel pairs. Acoustic results reveal significant compensatory articulation in XTH [ẽ], whereas [ĩ] exhibits gender differences, with only female speakers adopting a compensatory strategy (tongue retraction). Articulatory findings further confirm the compensatory lowering of tongue position in [ẽ] and additionally demonstrate incomplete compensation for [ã]. Across vowels, articulatory adaptation is found primarily in the vertical dimension, operating to offset the acoustic influence of VP coupling, bringing F1 in nasal vowels closer to their oral counterparts.