I rebooted, then closed every program I could think of and I still hear repeating after around 15 seconds:
Here's what it sounds like. (Minus the static, that's just the recording)
Is there any way of knowing which program is doing which sounds, or any sound at all? How do I start debugging this?
It is hard to tell over the static but for me it sounds like one of the default pidgin sounds.
It could also be the systembell.
To Further debug you sound you could kill the existing pulseaudio server, with
pulseaudio -k
. And launchpulseaudio -vvvvv
It could be that you have any kind of IM running in background? Is there anything visible running in your messagetray?