Recent studies have demonstrated that prompting large language models (LLM) with audio encodings enables effective speech understanding capabilities. However, most speech LLMs are trained on single-channel, single-talker data, which makes it challenging to directly apply them to multi-talker and multi-channel speech understanding task. In this work, we present a comprehensive investigation on how to enable directional multi-talker speech understanding capabilities for LLMs, specifically in smart glasses usecase. We propose two novel approaches to integrate directivity into LLMs: (1) a cascaded system that leverages a source separation front-end module, and (2) an end-to-end system that utilizes serialized output training. All of the approaches utilize a multi-microphone array embedded in smart glasses to optimize directivity interpretation and processing in a streaming manner. Experimental results demonstrate the efficacy of our proposed methods in endowing LLMs with directional speech understanding capabilities, achieving strong performance in both speech recognition and speech translation tasks.
@article{arxiv.2602.07211,
title = {Equipping LLM with Directional Multi-Talker Speech Understanding Capabilities},
author = {Ju Lin and Jing Pan and Ruizhi Li and Ming Sun and Yuzong Liu and Alaa Hassan and Jing Zheng and Florian Metze},
journal= {arXiv preprint arXiv:2602.07211},
year = {2026}
}