How to use language model in ASR Nemo

[wuchaowei2012]

I find out that little support from Nemo to use language model. If we have no LM model, the cer ratio might be quite high.

[okuchaiev]

This notebook demonstrates how you can use n-gram LM with QuartzNet and Jasper models
https://github.com/NVIDIA/NeMo/blob/main/tutorials/asr/Offline_ASR.ipynb

[jprobichaud]

I was indeed able to make this ( BeamSearchDecoderWithLM) work with CTC models that are character-based only. If I try to use it with a BPE model, like stt_en_citrinet_1024 for example, the results are very wrong.

Is it supposed to work with BPE models and I made a mistake? Where should I look if that's the case? Otherwise, is there a plan to have this work with BPE models?

Thanks!

[titu1994]

I discussed a little about LM support for Citrinet (any BPE model in general) here. We'll try to get it done soon.

#2039