How LLMs Assess Public Speaking? Methodology of Explaining LLM Judgments through Linguistic Patterns and Rhetorical Criteria

Abstract This study examines how Large Language Models, specifically GPT-4o-mini, evaluate public speaking performances based on textual transcripts. We collect a new annotation of speeches from the 3MT_French dataset and compare GPT-4o-mini annotations to those of an expert across both concrete rhetorical criteria and abstract subjective dimensions. In contrast to the expert, GPT-4o-mini exhibits limited cross-criterion integration and struggles with subjective judgments such as persuasiveness and creativity. Further, we utilise linguistic features in order to interpret provided annotations and demonstrated that GPT-4o-mini relies heavily on surface-level linguistic features and tends to prioritise structural and stylistic markers, while expert annotations reflect broader discourse-level understanding and persuasive intent. These findings highlight the limitations of using LLMs in high-level rhetorical evaluation and suggest the need for hybrid systems that combine model capabilities with theory-driven evaluation criteria. The annotated dataset and code are released to support future work in this direction: https://github.