1 Introduction

Explored the importance of interpersonal negotiation in academic English speeches and emphasized the role of symbolic resources in achieving the interpersonal function of academic discourse. The study focuses on a three minute English speech competition and explores the impact of multimodal intervention and modal synergy on speech effectiveness by analyzing the differences in audience intervention methods between winners and non winners.

2 Literature Review

Firstly, the role of intervention markers in academic English speeches was explored, pointing out that they are relatively common in written discourse research but relatively lacking in oral research. Intervention markers include questioning, reader reference, directive language, etc., aimed at enhancing persuasiveness and audience engagement. 3MT, as an emerging form of academic speech, requires contestants to introduce research to non professional audiences within a short period of time, and has high requirements for audience participation. Research has shown that the use of interlanguage in 3MT speeches is relatively frequent and there are differences between disciplines, but the synergistic effect of nonverbal modalities has not been fully considered.

3 Research Design

This study selected 30 hard subject speech videos of 3MT international finalists from 2016 to 2019, divided into an award-winning group and a non award-winning group, and constructed two corpora respectively. Intervention tagging is based on Hyland's theoretical framework, which includes five categories: audience reference, directive language, questioning, and shared knowledge, excluding additional language. Through AntConc software and manual verification, 481 speech intervention markers were ultimately obtained. Meanwhile, using ELAN software to annotate body language and exclude actions without communicative significance, it was found that the co-occurrence rate of body language and speech intervention markers in the award-winning group was lower than that in the non award-winning group. Modal synergy analysis adopts Colletta et al.'s framework, which includes five categories: reinforcement, integration, supplementation, clarification, and irrelevant or contradictory, independently completed by two annotators to ensure internal consistency.

4 Research findings and discussions

In a three minute academic English speech, there were significant differences in multimodal intervention and modality collaboration between the winning and non winning groups. The study found that there was no significant difference in the use of language intervention markers between the two groups of contestants, but the winning group performed better in the collaborative relationship between modalities. The winning group tends to use reinforced and integrated modal synergy, enhancing verbal information through body language, constructing meanings similar to speech, and promoting communication. In addition, the winning group demonstrated higher modal complexity in integrating information, skillfully utilizing body language and other modalities to enhance or integrate language content, and improve the efficiency of information transmission. In contrast, the non award winning group has a higher frequency of irrelevant modal collaborative relationships, exhibiting information inconsistency and forgetting words, reflecting a lack of multimodal communication skills. These differences indicate that the award-winning contestants pay more attention to audience awareness in their speeches and adopt audience oriented intervention strategies, thereby improving the persuasiveness and interactivity of their speeches.

5 Conclusion

This study is based on the concept of inter modal collaboration and analyzes the synergy between multimodal audience intervention methods and nonverbal and verbal interventions in 3MT. The results showed that there was no significant difference in verbal intervention methods among the award-winning group, but nonverbal intervention methods were significantly less than those of the non award-winning group, and more emphasis was placed on the synergy and complexity of verbal modalities. The research expands the study of meta discourse and suggests emphasizing the role of intervention markers in teaching, increasing students' awareness of multimodal audience intervention, and reducing the use of irrelevant body language. The interactivity of academic speeches is also reflected in aspects such as paralinguistic features, distance perception, and topic familiarity, which require further research.