Mm - hmm.
like a second maybe. And the reason for that is RASTA 's time window is too short to , um include the whole , um , reverberation  um , I don't know what you call it the reverberation response. I if you see wh if you see what I mean. The reverberation filter from my mouth to that mike is like  it 's t got it 's too long in the  in the time domain for the um  for the RASTA filtering to take care of it. And , um , then there are a couple of other speech enhancement approaches which haven't been tried for speech recognition yet but have just been tried for enhancement , which , um , have the assumption that um , you can do LPC um analysis of th of the signal you get at the far microphone and the , um , all pole filter that you get out of that should be good. It 's just the , um , excitation signal  that is going to be distorted by the reverberation and so you can try and reconstruct a better excitation signal and , um , feed that through the i um , all pole filter and get enhanced speech with reverberation reduced.
Mm - hmm. Mm - hmm.
There 's also this , uh , um , uh , echo cancellation stuff that we 've sort of been chasing , so , uh we have , uh  and when we 're saying these digits now we do have a close microphone signal and then there 's the distant microphone signal. And you could as a kind of baseline say , " OK , given that we have both of these , uh , we should be able to do , uh , a cancellation. " So that , uh , um , we  we , uh , essentially identify the system in between  the linear time invariant system between the microphones and  and  and  and re and invert it , uh , or  or cancel it out to  to some  some reasonable approximation