Speaking While Listening: A Survey and Empirical Audit of Full-Duplex Spoken Dialogue Systems

Jingyu Lu, Yuhan Wang, Jianming Luo, Yifu Chen, Tianle Liang, Shengpeng Ji, Ziyue Jiang, Xiaoda Yang, Yu Zhang, Xize Cheng, Chenyuhao Wen, Changhao Pan, Haoxiao Wang, Chen Ye, Jian Wu, Xiaoxi Jiang, Guanjun Jiang, Zhou Zhao


Abstract
More than a dozen spoken dialogue systems have recently claimed to be "full-duplex," yet the term has been used to describe substantially different capabilities. Existing surveys collapse them onto a single axis (cascaded/end-to-end, or engineered/learned) and miss the distinctions that matter most for builders. We argue that much of this ambiguity is taxonomical: current terminology does not specify where duplex decisions are made, which interaction types are supported, or how a system behaves moment by moment. This paper introduces three complementary frameworks: (i) an L,0-L,3 Architectural Hierarchy that locates where duplex decisions are made; (ii) a T x Ix R Interaction Ontology that specifies the temporal relation, user intent, and required system response for each interaction; and (i) a Decision State Machine(LDLE/LISTEN/SPEAK/WAIT/DUAL) that describes how systems move between states.Across published systems and benchmarks, our audit reveals a realization gap: although many architectures can in principle operate in full-duplex states, their observed behavior remains constrained by the interaction patterns represented in training and evaluation.We identify the open-source-versus-industrial data gap, as well as the still-unrealized goal of L3 representation-level modeling, as key frontiers for future research on full-duplex dialogue. The related material is available at https://github.com/MM-Speech/DuplexSurvey.
Anthology ID:
2026.emnlp-main.1126
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
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SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
25790–25824
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URL:
https://aclanthology.org/2026.emnlp-main.1126/
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Cite (ACL):
Jingyu Lu, Yuhan Wang, Jianming Luo, Yifu Chen, Tianle Liang, Shengpeng Ji, Ziyue Jiang, Xiaoda Yang, Yu Zhang, Xize Cheng, Chenyuhao Wen, Changhao Pan, Haoxiao Wang, Chen Ye, Jian Wu, Xiaoxi Jiang, Guanjun Jiang, and Zhou Zhao. 2026. Speaking While Listening: A Survey and Empirical Audit of Full-Duplex Spoken Dialogue Systems. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 25790–25824, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Speaking While Listening: A Survey and Empirical Audit of Full-Duplex Spoken Dialogue Systems (Lu et al., EMNLP 2026)
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https://aclanthology.org/2026.emnlp-main.1126.pdf