How can I add new words or vocabulary into kaldi platform?

Question

I am trying to create a ASR system with existing pre-trained models available as a sample. I got stuck in a place where how to add new words into that trained model, so that next time it will correctly return the word; Some sort of machine learning concept. Any ideas will be helpful.

Answer 1

There are two things you might need:

1. Lexicon: Try to find something like lexicon.txt in your data folder, add your words and corresponding phone sequences in it, like:

   speech s p iy ch
   the dh ax
   the dh iy
   

2. Language Model: Find something like XXX.lm in your data folder, add your word in 1-gram with a probabiliy, like:

   \data\
   ngram 1=200
   ngram 2=4000
   ...
   
   \1-grams
   -7.3241 the
   ...
   

After this, make the decoder HCLG.fst again based on these 2 new files.

Note: Numbers in language will make the results of speech recognition different, you need to choose a proper number, or use toolkit srilm to generate it by the text of your corpus.