An ultrasound investigation of Hnaring Lutuv (high?) vowels

Lutuv (also known as Lautu) is an under-documented Chin language from the Tibeto-Burman language family spoken by 18,000 people, both in Chin State in western Burma and in diaspora communities worldwide, including approximately 1000 people in the Indianapolis Chin refugee community. Lutuv utilizes a typologically rare six-way contrast in the higher part of the vowel space (i y ɨ ʉ ɯ u, see Bohnert et al. 2022), with an additional four high diphthongized vowels (ie̯ yə̯ ɯə̯ uo̯). Previous work has also identified that the high central vowels (/ɨ ʉ/) are poorly disambiguated—acoustically, they show considerable overlap with both each other and the high back vowels, and in terms of lip posture, they do not display the characteristics of a typical rounding contrast (Bohnert & Berkson 2023). The present work utilizes 3D ultrasonography to provide detailed lingual articulatory data of Lutuv vowels with special attention paid to the high central vowels, adding a new dimension to the existing acoustic and articulatory data. Real-time images of tongue position and motion provide new insights into the complex articulatory gestures involved in the production of these sounds and constitute the first ultrasound investigation into this underdocumented language.