Comment 26 for bug 550100

note: I have this issue in 4 computers; default settings of mythtv on ubuntu 12.04 and pulseaudio cause 'random' noise. And random means it can start at any action you do; after a pause, switching to program guide, it can happen (about 15% chance).
Another pause can fix it.
My solution to stay with Pulse audio without changing pulseaudio default settings:
in go to 'Advanced Audio Settings' on the audio Config Page.
Here activate 'Override SRC audio quality Sample rate conversion' and select 'Disabled'
Also activate 'Force audio device output to 48kHz".
The other option I kepped on the default settings.

This worked on my 4 computers, all with different hardware.

Walter