The development of linguistic studies has witnessed an extended research scope from sentence to discourse level. Researchers have combined discourse study to syntax, pragmatics, and other areas in linguistics, which to some extent fills in the gaps of traditional sentence-level studies. Besides, the rapid development of artificial intelligence has made it harder for sentence-level linguistic studies to meet the needs of society. Therefore, it is of both theoretical and applicational significance to conduct linguistic study on discourse level. Discourse study is featured by its close relationship to context, with several studies conducted to investigate the influence of context on discourse-level speech production and processing. Still, previous studies are more or less limited in their methodologies or theoretical scopes.
Against the background, the present study aims to offer new insights to how context influences speech production and processing on discourse level, through both production and perception experiments. Concerning speech production, the present study investigates the influence of inter-clause transition status on pause durations, and the influence of entities’ information structure and anaphora features on stress and boundary levels. Specifically, information structure is studied on both lexical and referential levels. Concerning speech processing, speech-neural entrainment is investigated to represent the level of speech processing. Neural entrainment to both context-based information and sensory information are compared, in terms of activated regions and overall entrainment levels.
In the production experiment, 14 reading texts selected from ASCCD (each read by 10 speakers) were annotated: transition status, information structure and anaphora features were annotated based on Centering Theory and RefLex annotation scheme, while stress and boundary levels were annotated based on C-ToBI. After extracting the aforementioned information using Praat, statistical analyses were conducted. In the perception experiment, EEG data of 18 participants were recorded while they were listening to 6 reading texts. Several multivariate Temporal Response Function models were trained with EEG signals as response, and context-based information and sensory information as stimuli respectively. The entrainment level was measured with the Pearson correlation coefficient between the reconstructed signal and the original signal, which was further submitted for statistical analysis.
The following conclusions are drawn from the experiment results. (1) During speech production, context information on clause level (i.e., transition status) has a significant influence on pause durations: the stronger the contexts’ effects are, the shorter the pause durations are. (2) Context information on entity level (i.e., information structure and anaphora features) has a significant influence on stress and boundary levels: the stronger the contexts’ effects are, the lower the stress and boundary levels are. (3) Accessible information are categorized as different information on lexical and referential levels, so it is important to distinguish linguistic form and reference. (4) During speech processing, both context-based information and sensory information mainly activate right temporal area, although context-based information activates a slightly larger range of brain region. (5) The overall entrainment level of context-based information is slightly higher than that of sensory information, suggesting a marginal facilitating effect of context. By placing the influence of context on both clause and entity level together, the present study reveals a consistent pattern of how context influences speech production on both levels, hence emphasizing the significance of multi-level interface studies. Besides, speech processing on discourse level was investigated with the method of cognitive neuroscience in the present study, as well as natural language processing, thus highlighting the advantages of interdisciplinary studies.
Key Words: context, reading texts, neural entrainment, stress, pause