MTLM: an Innovative Language Model Training Paradigm for ASR

Pre-training Transformer-based language models (LMs) on a large amount of text has proven crucial for improving automatic speech recognition (ASR) performance. Generally, traditional LMs are unidirectional and unable to access the context on the right. This paper proposes a method for training LMs that enable traditional unidirectional LMs to fully utilize left and right contexts. Compared with the unidirectional LMs, our LM facilitates ASR to transcribe hypotheses more consistently and in a more semantically unambiguous way, as it incorporates richer contextual representations. Finally, our experimental results on the LibriSpeech corpus demonstrate that our model outperforms traditional unidirectional LMs, whether n-best rescoring or shallow fusion is used as the decoding algorithm.