Speech-XL: Towards Long-Form Speech Understanding in Large Speech Language Models

Haoqin Sun, Chenyang Lyu, Shiwan Zhao, Xuanfan Ni, Xiangyu Kong, Longyue Wang, Weihua Luo, Yong Qin


Abstract
Despite the growing success of Large Speech Language Models (LSLMs) in processing short-term acoustic signals, their extension to long-form audio understanding is severely bottlenecked. This limitation stems from the limited context length and the exorbitant memory footprints required for long-form inference. In this work, we propose Speech-XL, a new model that capitalizes on the intrinsic key-value (KV) sparsification capacity of Large Language Models (LLMs) to achieve high-ratio speech input compression. Specifically, we introduce a novel special token, the Speech Summarization Token (SST), for each speech interval to encapsulate the intra-interval speech information into its associated KV pairs. The SST module is trained via instruction fine-tuning, employing a curriculum learning strategy where the SST learns to compress information in a progressive manner—advancing from low-ratio (simple) to high-ratio (challenging) compression. Despite using substantially less training data than large-scale audio foundation models, Speech-XL achieves competitive compression quality under the same backbone, maintaining a small gap to its uncompressed counterpart while substantially reducing long-form inference cost. By addressing the long-standing bottlenecks in long-form audio modeling, our approach offers a novel perspective on the condensation of extensive acoustic sequences.
Anthology ID:
2026.findings-emnlp.250
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
5255–5267
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.250/
DOI:
Bibkey:
Cite (ACL):
Haoqin Sun, Chenyang Lyu, Shiwan Zhao, Xuanfan Ni, Xiangyu Kong, Longyue Wang, Weihua Luo, and Yong Qin. 2026. Speech-XL: Towards Long-Form Speech Understanding in Large Speech Language Models. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 5255–5267, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Speech-XL: Towards Long-Form Speech Understanding in Large Speech Language Models (Sun et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.250.pdf