The streaming automatic speech recognition (ASR) models are more popular and suitable for voice-based applications. However, non-streaming models provide better performance as they look at the entire audio context. To leverage the benefits of the non-streaming model in streaming applications like voice search, it is commonly used in second pass re-scoring mode. The candidate hypothesis generated using steaming models is re-scored using a non-streaming model. In this work, we evaluate the non-streaming attention-based end-to-end ASR models on the Flipkart voice search task in both standalone and re-scoring modes. These models are based on Listen-Attend-Spell (LAS) encoder-decoder architecture. We experiment with different encoder variations based on LSTM, Transformer, and Conformer. We compare the latency requirements of these models along with their performance. Overall we show that the Transformer model offers acceptable WER with the lowest latency requirements. We report a relative WER improvement of around 16% with the second pass LAS re-scoring with latency overhead under 5ms. We also highlight the importance of CNN front-end with Transformer architecture to achieve comparable word error rates (WER). Moreover, we observe that in the second pass re-scoring mode all the encoders provide similar benefits whereas the difference in performance is prominent in standalone text generation mode.

本文研究了基于注意力机制的端到端语音识别模型在Flipkart语音搜索任务的应用，使用编码器-解码器LAS架构实现非流式和流式模型并比较它们的性能和延迟要求，结果表明变压器模型具有可接受的词错误率和最低延迟要求，在第二次LAS二次得分中相对WER以5ms以内的延迟开销提高16％左右，此外，观察到在第二次得分模式下，所有编码器提供的好处相似，而性能的差异则在独立文本生成模式下更为突出。

基于关注机制端到端语音识别的编码器比较：独立识别模式与重打分模式