M3-SLU: Evaluating Speaker-Attributed Reasoning in Multimodal Large Language Models
Yejin Kwon, Taewoo Kang, Hyunsoo Yoon, Changouk Kim
TL;DR
M3-SLU introduces a targeted benchmark for speaker-attributed reasoning in multimodal large language models by combining four public multi-speaker corpora into 12,873 validated segments. It defines two tasks—Speaker-Attributed QA and Utterance Matching—and deploys a four-stage data construction pipeline with both automated GPT-4o-based generation/validation and final human checks, supplemented by an LLM-as-Judge evaluation framework. Across SDR and end-to-end MLLM experiments, results show models can extract what was said but struggle to correctly identify who spoke when, highlighting a persistent gap in speaker-grounded dialogue understanding. The benchmark provides a realistic, long-form multi-speaker evaluation platform to guide future work on speaker roles, turn-taking, and dialogue grounding in multimodal systems, moving beyond transcription accuracy toward true speaker-aware reasoning.
Abstract
We present M3-SLU, a new multimodal large language model (MLLM) benchmark for evaluating multi-speaker, multi-turn spoken language understanding. While recent models show strong performance in speech and text comprehension, they still struggle with speaker-attributed reasoning, the ability to understand who said what and when in natural conversations. M3-SLU is built from four open corpora (CHiME-6, MELD, MultiDialog, and AMI) and comprises over 12,000 validated instances with paired audio, transcripts, and metadata. It includes two tasks: (1) Speaker-Attributed Question Answering and (2) Speaker Attribution via Utterance Matching. We provide baseline results for both cascaded pipelines and end-to-end MLLMs, evaluated using an LLM-as-Judge and accuracy metrics. Results show that while models can capture what was said, they often fail to identify who said it, revealing a key gap in speaker-aware dialogue understanding. M3-SLU offers as a challenging benchmark to advance research in speaker-aware multimodal understanding.
