Comment 0 for bug 279478

Binary package hint: alsa-base

Sound works fine from the speakers, but when headphones are plugged in, sound gradually diminishes until it is silent. Unplugging the headphones leaves it silent on the speakers. Reboot resets the position and sound is fine until 'phones plugged in.

My card is a "Sigmatel STAC9227" in a Dell Dimension e520 desktop but it seems to affect similar cards.

More info of the problem: http://ubuntuforums.org/showthread.php?t=913328&page=3

To address this, you can restart alsa and pulseaudio:

 sudo alsa force-reload
 pulseaudio

Presumably, this can be fixed by adding an option to /etc/modprobe.d/alsa-base but I haven't tested it yet:

 options snd-hda-intel model=dell-3stack