GNOME Bugzilla – Bug 697964
If speakers are playing a sound, then plugging the headphone does not stop the speaker
Last modified: 2013-04-15 07:25:02 UTC
If speakers are playing a sound and a headphone is plugged, the speaker does not automatically transfer sound output to the headphone. Both speaker and headphone play the sound together.
This is unlikely to be a gnome-control-center problem. It is hardware related, and as such, this would be more related to ALSA or possibly PulseAudio.
If I attach the headphone and reboot, the sound output always plays on the headphone even if I pull them out. Both speakers and headphone play sound output if I boot without attaching the headphone.
This is a problem with PulseAudio or ALSA's routing. You should bring this up with your distribution's kernel tracker.