Lip posture of high and high-mid vowels in Hnaring Lutuv

Abstract

Lutuv is an under-documented South Central Tibeto-Burman language which is reported to contain six high monophthongs /i, y, ɨ, ʉ, Ɯ, u/ and four diphthongal vowels with high onsets /ie̯, yə̯, uɔ̯, Ɯə̯/ (Bohnert etal., 2022). No articulatory work on Lutuv exists to date, but impressionistic observations suggest that while the contrast between /i, y/ and /u, Ɯ/ is one of rounding (as implied by their IPA transcriptions), the contrast between /ɨ, ʉ/ is instead one of lip spreading. In addition, /ʉ/ seems to involve a degree of frication from labiodental contact. To further investigate these observations, the current paper utilizes facial landmark recognition through OpenFace 2.0 (Baltrusaitis et al., 2018) to analyze the lip posture of these vowels, measuring horizontal, vertical, and lateral lip aperture over the duration of each vowel produced by one native speaker in a curated word list. These measurements are compared both within and across pairs to determine (1) the articulatory characteristics of Lutuv rounding contrasts, and (2) whether the central high vowels display these characteristics. These data complement existing acoustic analyses and provide a more detailed understanding of the articulation of a typologically rare contrast.