Mm - hmm.
because people move around , and uh , if  if it 's  if it 's uh not a simple echo , like a cross - talk kind of echo , but it 's actually room acoustics , it 's  it 's  it 's  you can't really do inversion ,
Mm - hmm.
and even echo cancellation is going to uh be something  It may  you  Someone may be moving enough that you are not able to adapt quickly and so the tack that we 've taken is more " lets come up with feature approaches and multi - stream approaches and so forth , that will be robust to it for the recognizer and not try to create a clean signal ".