  Masked Language Models (MLMs) have proven to be effective for second-pass
rescoring in Automatic Speech Recognition (ASR) systems. In this work, we
propose Masked Audio Text Encoder (MATE), a multi-modal masked language model
rescorer which incorporates acoustic representations into the input space of
MLM. We adopt contrastive learning for effectively aligning the modalities by
learning shared representations. We show that using a multi-modal rescorer is
beneficial for domain generalization of the ASR system when target domain data
is unavailable. MATE reduces word error rate (WER) by 4%-16% on in-domain, and
3%-7% on out-of-domain datasets, over the text-only baseline. Additionally,
with very limited amount of training data (0.8 hours), MATE achieves a WER
reduction of 8%-23% over the first-pass baseline.
