Comment 18 for bug 970009

After searching a bit further, I found the following instructions to create the correct String:

* Open "Sound Settings" (Alt+F2 and type: pavucontrol).
* Select the "Output Devices" Tab.
* Annotate the device's name, leaving out spaces and all characters from this list: ()[]-/
* Now add "Playback" to the beginning and "PulseAudioMixer" to the end of name annotated in the previous step. For me the correct value is: PlaybackBuiltinAudioAnalogStereoPulseAudioMixer

The instructions were taken from here:
  http://xubuntugeek.blogspot.ch/2012/05/fix-adjust-sound-with-multimedia-keys.html

So it did work finally work for me, by following the instructions.