Comment 1 for bug 147682

If you want a temporary workaround, then run this command:

sudo echo "options snd-hda-intel model=5stack" >> /etc/modprobe.d/alsa-base

Make sure your speakers and microphone are not muted. I think the best mixer for that is gnome-alsamixer.

I am implementing a fix in Gutsy l-u-m that detects this particular codec and initializes it correctly.