After a long hassle with varying sound libraries over the years, I’ve been relatively happy with how pulseaudio turned out for a while now. It still has its quirks, but it’s been mostly working fine for the last few versions of Ubuntu, and some of the configuration features are really useful. I’m using my onboard sound card for system sounds and an SB Live! for music and video, and pavucontrol makes it easy to permanently redirect different applications to specific cards.
Or at least, I’d been relatively happy until I updated to Ubuntu 12.10 a few weeks ago. Suddenly, sounds played through KDE’s Phonon would sound garbled for at least several seconds. mplayer and other tools that don’t go through Phonon sounded fine, but KDE system sounds and Amarok’s music output would be horribly distorted. Jumping around in the audio stream a few times would fix Amarok’s output (until playback stopped and I hit the play button again), but that didn’t really make me happy.
This bug report provided the solution (reply #23 to be exact).
Turns out the current version of pulseaudio seems to have scheduling issues with some broken Alsa drivers, and those drivers apparently include those for the SB Live!. A pulseaudio module parameter fixes the issue.
load-module module-udev-detect tsched=0
This switches pulseaudio to the older scheduling mode and gets rid of the glitches.