I've followed this :
Howto - Resolve no sound problem on Ubuntu 12.10, 12.04 and Older
In addition, I've disabled auto-mute in alsamixer. If I play a sound under VLC, I can see in pavu, that there's something playing - that the volume is registered - yet I hear nothing.
I recall my sound working prior to about a week ago, but it seems to have abruptly stopped on its own.