Comment 51 for bug 190754

This bug still exists for me.

I am on a completely updated system (as of 5 minutes ago), and I also did

sudo apt-get purge pulseaudio && sudo apt-get install pulseaudio

as recommended above. This has led to no improvement.

Note: It does appear that the bug sometimes 'vanishes' for periods of time. E.g. right after booting up, I might be able to alt-tab between a few apps before sound crackling occurs. Once the crackling occurs, it generally will continue to persist for all further alt-tabs (at least between apps that need to redraw themselves in a non-trivial way, which includes Firefox, Nautilus, gedit, etc., assuming open documents in all of them).