Comment 36 for bug 252335

Okay, I have to edit my last statement. Suddenly I am now getting crackling and pops with two audio streams playing at once. In this case rhythmbox and pidgin playing sound at the same time. Reverting to Intrepid's current pulseaudio resolved that issue.

The only thing relevant (I think) I changed between working perfectly and the crackling was editing my asound.conf to read:
pcm.pulse {
    type pulse
}
ctl.pulse {
    type pulse
}
pcm.!default {
    type pulse
}
ctl.!default {
    type pulse
}

This was required to get audio working with flashplugin-nonfree.