Ultrasound Study of Tongue Contours of Tonal Words of Manipuri

Abstract

Introduction: Manipuri is a tonal language with conflicting tonal organisation, and recent studies highlighted two distinctive tones, i.e., level and falling tones (Singh, 2019; Devi & Das, 2021). Syllabic and tonal knowledge is crucial to distinguish a spoken word in a tonal language. Studies to date have not explored tongue dynamics in Manipuri. Very few studies have explored the laryngeal and extra- laryngeal structures contributing to tone differentiation in tonal languages like Burmese and Chinese using acoustical and physiological methods (Erickson et al., 2004; Shastri & Kumar, 2015; Moisik et al., 2014). However, there is no physiological study conducted to understand the articulatory dynamics of the tongue in Manipuri. Aim and objectives: The current study aimed to understand the tongue contours of monosyllabic level and falling tonal counterparts in Manipuri. The objectives were 1) To obtain tongue contours during the production of monosyllabic level and falling tonal counterparts in Manipuri. 2) To compare the horizontal tongue dynamics across anterior r, mid and posterior tongue regions between level and falling tonal counterparts. 3) To compare the vertical tongue dynamics across anterior, mid and posterior tongue regions between level and falling tonal counterparts.4) To find any effect of gender on the horizontal and vertical tongue dynamics of the two tonal words. Method: A total of 10 healthy native speakers of Manipuri, 5 males and 5 females between the age ranges of 20-35 years were enrolled in the study. The Mindray Ultrasound 6600 and Articulate Assistant Advanced (AAA) software were used to record 20 sentences of 10 monosyllabic tonal words (V, CV and CVC) each in level and falling tone. AAA software was used to analyze the acquired tongue images based on the (x-y) coordinates of the tongue's anterior, mid, and posterior regions. Results: The findings of the study revealed significant differences in horizontal tongue dynamics between level and falling tone at tongue mid region with no significant difference in anterior and posterior tongue region. Vertical tongue dynamics were not significantly different for the tonal counterparts. There were no gender effects in tonal differentiation in Manipuri. Discussion: The present study provided insight into the involvement of articulatory dynamics for various tones in Manipuri. The finding revealed a significant mid-tongue retraction phenomenon for tone differentiation. While there was a significant change in horizontal tongue dynamics, the vertical counterpart, i.e., tongue height, did not show any significant difference. Conclusion: This is the first study to provide insights on tone differentiation using ultrasound tongue imaging techniques in Manipuri. The study provides visualizations of tongue contours that can be used for assessment and intervention of tone differentiation in native or new language learners in Manipuri.