Chronological Thinking in Full-Duplex Spoken Dialogue Language Models
Summary
Full-duplex spoken dialogue language models (SDLMs) listen and speak at the same time. While the user talks, though, current systems just emit a stream of silence tokens. This wastes the listening period and may push an autoregressive model toward degenerate repetition. The authors propose CT-SDLM (implemented as CT-Duplex), which fills that period with Chronological Thinking: a compact chain of structured reasoning nodes produced step by step as speech arrives.
The node types draw on the ACT-R cognitive architecture. Thinking is strictly causal, using only audio heard so far, and can be cut off at any point. The agent therefore starts replying as soon as the user stops, with no added delay.
The architecture has four parts:
- a streaming speech encoder
- an LLM backbone that predicts only text tokens
- a separate Transformer decoder that produces speech tokens
- an audio codec
Thinking improves response quality, especially on reasoning-heavy task-oriented dialogue, and helps little on factual QA. Turn-taking and barge-in performance stay competitive. The work suggests idle listening time can be turned into useful computation in real-time voice agents.
Key points
- The thinking chain uses five node types mapped to ACT-R modules and replaces the <SIL> tokens. The user speech encoder runs at 12.5 Hz.
- On SpokenWOZ, thinking gives an 8.75% improvement. Gains on MtBenchEval multi-turn dialogue are modest, and on Llama Questions and Web Questions they are negligible.
- The 1.7B model beats larger full-duplex baselines such as Moshi (7B) on factual QA. GLM-4-Voice, a half-duplex 9B model, scores higher.
- On the Impatient dataset, barge-in success rises from 88.63% to 94.05% with thinking, and barge-in latency is roughly unchanged (0.53 → 0.54). Turn-taking latency increases from 0.45 to 0.68, which the authors still describe as comparable.
- In an A/B test with 10 raters on SpokenWOZ, the thinking variant was preferred for both audio fidelity and content quality, with win rates of about 55–64%.
Cite
@inproceedings{wu2026chronological,
title = {{Chronological Thinking in Full-Duplex Spoken Dialogue Language Models}},
author = {Wu, Donghang and Zhang, Haoyang and Chen, Chen and Zhang, Tianyu and Tian, Fei and Yang, Xuerui and Yu, Gang and Liu, Hexin and Hou, Nana and Hu, Yuchen and Chng, Eng Siong},
booktitle = {Proceedings of the 27th Annual Meeting of the Special Interest Group on Discourse and Dialogue},
year = {2026},
doi = {10.18653/v1/2026.sigdial-1.33},
url = {https://doi.org/10.18653/v1/2026.sigdial-1.33}
}References
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