This is the simplest ASR recipe in icefall.
It can be run on CPU and takes less than 30 seconds to get the following WER:
[test_set] %WER 0.42% [1 / 240, 0 ins, 1 del, 0 sub ]
Please refer to https://icefall.readthedocs.io/en/latest/recipes/yesno/index.html for detailed instructions.