Comment 67 for bug 178442

@paul: make sure you don't leave changes from one solution when you try another; I had a bit of a problem transitioning between two solutions precisely because of this. Your comment:

>I was still getting sound out of Audacity [...] After numerous attempts to reconfigure I now get no sound anywhere :(

suggests that you've done something which has broken ALSA, so any fiddling with pulseaudio won't help until you undo whatever it is you did there -- most likely you need to remove /etc/asound.conf and/or ~/.asoundrc, and forcing a reinstallation of ALSA and pulseaudio may help to clear things up.