将大模型语义先验融入编码器,实现快速多说话人语音识别
Distilling LLM Semantic Priors into Encoder-Only Multi-Talker ASR with Talker-Count Routing
- 用大模型做教师指导,将语义先验蒸馏到编码器中
- 三说话人场景下性能显著提升,实时因子(RTF)大幅降低
- 支持可变说话人数,动态路由选择解码分支
大型语言模型(LLM)具备强大的语义先验,可提升多说话人自动语音识别(MT-ASR)性能,但将其作为自回归解码器计算开销大且在严重重叠下表现脆弱。本文提出一种编码器仅结构的MT-ASR框架,将LLM适配为多说话人条件,并在训练中将其语义指导蒸馏至编码器,推理时保留快速的CTC式解码。模型采用后编码器分离器与序列化CTC生成有序转录,利用改进的基于LLM的SOT目标作为多说话人感知的教师信号,显式正则化混合语音表示。为进一步支持可变说话人数,引入说话人数量头(Talker-Count Head),预测说话人数并动态选择解码分支。在LibriMix数据集上的实验表明,该模型在双说话人条件下达到与基于LLM系统相当的性能,而在三说话人条件下有显著提升,且实时因子(RTF)明显减小。
原文摘要 · Abstract (English)
Large language models (LLMs) provide strong semantic priors that can improve multi-talker automatic speech recognition (MT-ASR), but using an LLM as an autoregressive decoder is computationally expensive and remains fragile under heavy overlap. In this paper, we propose an encoder-only MT-ASR framework that adapts an LLM to multi-talker conditioning and distills its semantic guidance into the encoder during training, while retaining fast CTC-style decoding at inference. Our model employs a post-encoder separator with serialized CTC to produce talker-ordered transcripts, and leverages an adapted LLM-based SOT objective as a multi-talker-aware teacher signal to explicitly regularize mixed-speech representations. To further support variable numbers of talkers, we introduce a Talker-Count Head that predicts the talker count and dynamically selects the appropriate decoding branch. Experiments on LibriMix show that the proposed encoder-only model achieves comparable performance to LLM-based systems in the two-talker condition, while delivering significant improvements in the three-talker condition with significant small RTF.
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