The restriction has been removed completely and AECM now supports any number of higher bands. But this has been achieved by always zeroing out the higher bands, instead of applying a constant gain which is the average over half of the lower band (like it is done for the AEC), because that would be non-trivial to implement and we don't want to spend too much time on AECM, since we want to get rid of it in the long term anyway. R=peah@webrtc.org, solenberg@webrtc.org, tina.legrand@webrtc.org Review URL: https://codereview.webrtc.org/1774553002 . Cr-Commit-Position: refs/heads/master@{#11931}