DuplexJev-4B

📄 Paper: arXiv:2610.02638 · Code: github.com/adventists-ai/duplexjev

Built on Qwen3-4B + the Qwen3-ASR-0.6B audio encoder.

DuplexJev reads typed, closed-set decisions from speech (has the user finished? which filler fits? who is speaking, in what mood?) as a single-token distribution of a frozen LLM: zero decode steps, many questions about the same clip in parallel. This repository is the complete model (encoder + trained connector + LLM, 4.2 B parameters, bf16) and runs on vLLM with a small plugin.

Audio encoder (frozen)	Qwen3-ASR-0.6B encoder, 12.5 frames/s
Connector (trained, 12.6 M)	2 frames stacked → 6.25 audio tokens/s → SwiGLU MLP → LLM width
LLM (frozen)	Qwen3-4B, used without thinking
Training	content alignment (transcript distillation), then turn-taking + gender + emotion under the mixed objective (2026-10-01 update)
Try it online	api.adventists.cn/duplexjev (web demo and trial API, this model)

Serve with vLLM

pip install "vllm[audio]>=0.29" duplexjev-vllm
vllm serve adventists-ai/DuplexJev-4B --max-model-len 4096

duplexjev-vllm registers the model with vLLM (Qwen3-ASR encoder + connector; the LLM runs on vLLM's own Qwen3 kernels). Tested with vLLM 0.29 on one GPU; the model needs about 8 GB plus KV cache.

Each question is one chat request with max_tokens=1: list the options under letters and read the log-probabilities of the letters. Requests about the same clip share the prompt prefix (chat header + audio), which vLLM's prefix cache computes once. A ready-made client (openai + standard library only) is examples/vllm_client.py:

from vllm_client import DuplexJevClient

dj = DuplexJevClient("http://localhost:8000/v1")
dj.decide(open("call.wav", "rb").read(), {
    "turn":    ("Has the user finished speaking?", ["finished", "not finished"]),
    "gender":  ("What is the perceived gender of the speaker?", ["female", "male"]),
    "emotion": ("What is the speaker's emotional state?", ["neutral", "happy", "angry", "sad"]),
})
# {'turn': {'answer': 'finished', 'confidence': 0.88, 'probs': {...}}, 'gender': {...}, 'emotion': {...}}

The prompt it sends, which is the format the connector was trained on:

The user said: <|audio|>

Question: What is the perceived gender of the speaker?

Options:
A. female
B. male

Answer with only the letter of the correct option.

For Chinese speech ask in Chinese: 用户说：<|audio|>, 问题：…, 选项：, 请只回答正确选项的字母。 Send the audio as an input_audio part next to that text; restrict the answer with allowed_token_ids (the letter tokens) and set logprobs=True. The chat template turns thinking off by default.

Results

Paper protocol (single-token readout; % correct):

version	qa100	ZJU-ML	Easy-Turn	gender (800)	emotion (800, 4-way)	total
current (2026-10-01)	74	50	78.1*	88.6	91.2	78.6
first release (2026-09-28, in the repo history)	72	51	60.2	89.4	91.9	75.9

* The current version's decision stage includes the Easy-Turn training split (disjoint from the 800-item test set, different wording), so Easy-Turn is in-domain for it. Total = mean of main language (qa100, ZJU-ML, Easy-Turn) and paralinguistics (gender, emotion).

Served by vLLM 0.29 with duplexjev-vllm, questions in the wording of the client above: qa100 74, ZJU-ML 52, Easy-Turn 77.9, gender 87.8, emotion 86.0. One decision event (8 questions about one clip) takes about 80 ms on a shared H100.

qa100: 100 bilingual spoken multiple-choice questions (adventists-ai/qa100). ZJU-ML: main-language part of the ZJU audio benchmark v2.0.0. Easy-Turn: 800-item four-way turn-state test set (see the GitHub README for the reference). Gender: 800 real utterances (AISHELL-1, LibriSpeech). Emotion: 800 utterances (ESD, CREMA-D).

Limitations

• Evaluated on short read or acted speech; not on streaming input.
• Spoken factual QA is much weaker than in DuplexJev-32B.
• Emotion labels come from acted corpora; do not use the outputs to make decisions about individuals.

License

CC BY-NC 4.0, research use only. The connector was trained on the ESD emotional speech corpus, which is licensed for research purposes only, and on CREMA-D (ODbL). The base models keep their own licences: Qwen3-4B and Qwen3-ASR-0.6B are Apache-2.0 (Copyright Alibaba Cloud); this repository redistributes their weights unchanged.

Citation

@misc{jin2026duplexjev,
  title         = {Batched Speech Decisions Without Decoding: Single-Token Supervision Lets a Frozen {LLM} Hear Beyond the Transcript},
  author        = {Jin, Jie and Ma, Ziyin and Yin, Min and Chen, Jinyu and Song, Haigang and Pang, Zhikun and Zhang, Xiaowen},
  year          = {2026},
  eprint        = {2610.02638},
  archivePrefix = {arXiv},
  note          = {Submitted to IEEE ICASSP 2027}
}

Built by Adventists.ai. Claude (Anthropic) assisted with code.