Analyzing discourse functions with acoustic features and phone embeddings: non-lexical items in Taiwan Mandarin

Analyzing discourse functions with acoustic features and phone embeddings: non-lexical items in Taiwan Mandarin Pin-Er Chen National Taiwan University cckk2913@gmail.com Yu-Hsiang Tseng National Taiwan University seantyh@gmail.com Chi-Wei Wang National Taiwan University r09142007@ntu.edu.tw Fang-Chi Yeh National Tsing Hua University fangchiyeh2000@gmail.com Shu-Kai Hsieh National Taiwan University shukaihsieh@ntu.edu.tw Abstract Non-lexical items are expressive devices used in conversations that are not words but are nevertheless meaningful. These items play crucial roles, such as signaling turn-taking or marking stances in interac- tions. However, as the non-lexical items do not stably correspond to written or phono- logical forms, past studies tend to focus on studying their acoustic properties, such as pitches and durations. In this paper, we investigate the discourse functions of non- lexical items through their acoustic proper- ties and the phone embeddings extracted from a deep learning model. Firstly, we create a non-lexical item dataset based on the interpellation video clips from Taiwan’s Legislative Yuan. Then, we manually iden- tify the non-lexical items and their dis- course functions in the videos. Next, we an- alyze the acoustic properties of those items through statistical modeling and building classifiers based on phone embeddings ex- tracted from a phone recognition model. We show that (1) the discourse functions have significant effects on the acoustic features; and (2) the classifiers built on phone embeddings perform better than the ones on conventional acoustic properties. These results suggest that phone embed- dings may reflect the phonetic variations crucial in differentiating the discourse func- tions of non-lexical items. Keywords: non-lexical item, discourse function, acoustic property, acoustic represen- tation, pragmatics 1 Introduction People’s everyday interactions include sounds that are not verbal words in the traditional sense. These sounds, such as sighs, sniffs, and grunts, are used in indexing the turn-taking in dialogues, marking stance, showing affections, and expressing roles and meanings in conversa- tions (Dingemanse, 2020). Examples of these non-lexical items are un-huh in English as a marker showing understanding and attentive- ness, while the single syllable uh and um act as fillers and disfluency markers (Ward, 2006; Buschmeier et al., 2011). While these non-lexical items are important linguistically, they pose an interesting chal- lenge to linguistic inquiry. Non-lexical items do not belong to a major word class, and some do not conform to the language’s phonologi- cal requirements (Keevallik and Ogden, 2020). Moreover, while the phonetic properties of non-lexical items could be generally described, they are nevertheless “phonetically underspeci- fied.”(Keating, 1988) For example, in the study of “moan” in board game interactions, Hof- stetter (2020) found “moans” involve phonetic properties related to open vowels, irrespective of their frontness, backness, or roundedness. The study suggests that a non-lexical item can not be represented as a single phonetic sym- bol; instead, it may refer to the vowel space for which we do not have a general phonetic symbol. Some studies, therefore, analyze these items in terms of their acoustic properties: the components’ sound (Ward, 2006), the funda- mental frequencies, durations, and intensities. (Shan, 2021; Ballier and Chlébowski, 2021). In contrast to the conventional …

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