实时流式语音识别中,用关键词检测提升罕见词识别准确率。
Contextual Biasing for Streaming ASR via CTC-based Word Spotting

- 通过状态传递算法跟踪跨音频块的关键词路径。
- 延迟低、输出稳定,关键词识别F值显著提升。
- 无需修改模型或训练,适合实际部署。
上下文偏置对提升自动语音识别(ASR)系统中罕见词和领域特定词的识别至关重要。尽管近年来已有多种方法提出,但多数集中在离线场景,未明确解决流式ASR的挑战。例如,基于CTC的关键词检测(CTC-WS)可通过直接从CTC对数概率中检测关键词实现优异性能,但仅适用于离线处理,需完整语音片段。本文提出一种面向实时上下文偏置的流式扩展方法。该方法利用状态保持的标记传递算法,在音频块间维持活跃关键词路径,实现跨块关键词检测。为确保低延迟与输出稳定性,引入增量承诺机制,仅输出确定不会受未来音频影响的片段,而推迟不确定区域。该方法可自然集成至流式ASR流水线,无需修改底层声学模型或额外训练,具备实际部署可行性。实验表明,该方法在降低整体字错误率(WER)的同时,有效提升了关键词识别的F-score,验证了其在实时ASR应用中的有效性。
原文摘要 · Abstract (English)
Contextual biasing is essential to improving the recognition of rare and domain-specific words in an automatic speech recognition (ASR) system. While numerous methods have been proposed in recent years, most of them focus on offline settings and do not explicitly address the challenges of streaming ASR. For example, CTC-based word spotting (CTC-WS) have demonstrated strong performance by directly detecting keywords from CTC log-probabilities, but they are limited to offline processing and require access to the full utterance. In This work, we present a streaming extension of CTC-WS for real-time contextual biasing. Our method maintains active keyword paths across audio chunks using a stateful token passing algorithm, enabling the detection of keywords that span multiple chunks. To ensure low latency and stable output, we introduce an incremental commitment mechanism that only emits segments guaranteed not to be affected by future audio, while deferring uncertain regions. This method naturally integrates with streaming ASR pipelines and does not require modifications to the underlying acoustic model or additional training, making it practical for real-world deployment. Experimental results show that our method reduces overall WER and effectively improves keyword F-score, demonstrating its effectiveness for real-time ASR applications.
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