Ran Han
Author directory2026
Dynamic routing-based Mixture of Layer-wise Tokens with Token-Difficulty for Robust Audio-Visual Speech Recognition
Changhan Oh | Yeeun Jo | Ran Han | Jeomja Kang | Woo Yong Choi | Hwa Jeon Song | Kiyoung Park
Findings of the Association for Computational Linguistics: EMNLP 2026
Changhan Oh | Yeeun Jo | Ran Han | Jeomja Kang | Woo Yong Choi | Hwa Jeon Song | Kiyoung Park
Findings of the Association for Computational Linguistics: EMNLP 2026
Audio-Visual Speech Recognition (AVSR) systems typically consume only the final-layer representation of their modality-specific encoders. In self-supervised (SSL) encoders, lower and upper layers encode acoustic and more abstract linguistic cues respectively, so the most informative layer may differ from token to token. We propose Mixture of Layer-wise Tokens (MoLT), which aggregates the per-layer outputs of the AV-HuBERT encoder per token through an MoE-style router. A sparse top-k MoLT (S-MoLT) selects the most useful layers per token, and Dynamic routing-based MoLT (D-MoLT) replaces the fixed k with a learnable per-token threshold. To align routing with recognition difficulty, we further add a token-difficulty-aware lower-upper preference that biases, rather than overrides, the learned routing: Difficulty-adaptive D-MoLT (DD-MoLT) derives the difficulty signal from one modality, while Cross-modal DD-MoLT (CDD-MoLT) uses the audio-video reliability gap. On LRS3, our models consistently improve WER over a strong MMS-LLaMA baseline across SNR conditions, with the gain widening under severe noise (e.g., 13.85 vs. 17.10% at−15 dB), at negligible overhead.
2022
Learning to Embed Multi-Modal Contexts for Situated Conversational Agents
Haeju Lee | Oh Joon Kwon | Yunseon Choi | Minho Park | Ran Han | Yoonhyung Kim | Jinhyeon Kim | Youngjune Lee | Haebin Shin | Kangwook Lee | Kee-Eung Kim
Findings of the Association for Computational Linguistics: NAACL 2022
Haeju Lee | Oh Joon Kwon | Yunseon Choi | Minho Park | Ran Han | Yoonhyung Kim | Jinhyeon Kim | Youngjune Lee | Haebin Shin | Kangwook Lee | Kee-Eung Kim
Findings of the Association for Computational Linguistics: NAACL 2022
The Situated Interactive Multi-Modal Conversations (SIMMC) 2.0 aims to create virtual shopping assistants that can accept complex multi-modal inputs, i.e. visual appearances of objects and user utterances. It consists of four subtasks, multi-modal disambiguation (MM-Disamb), multi-modal coreference resolution (MM-Coref), multi-modal dialog state tracking (MM-DST), and response retrieval and generation. While many task-oriented dialog systems usually tackle each subtask separately, we propose a jointly learned multi-modal encoder-decoder that incorporates visual inputs and performs all four subtasks at once for efficiency. This approach won the MM-Coref and response retrieval subtasks and nominated runner-up for the remaining subtasks using a single unified model at the 10th Dialog Systems Technology Challenge (DSTC10), setting a high bar for the novel task of multi-modal task-oriented dialog systems.