I was playing music with my headphones plugged in. The music was coming out of the headphones, but I also noticed that my speakers were playing the same music.
Why is this, and how can I fix it?
This is probably an alsa issue. I had the same problem, but it got reported as a bug and fixed.
I had the same issue. It appears that the new kernel did not correctly detect the sound card model that you have. You will have to edit the
/etc/modprobe.d/alsa-base.conf file and set the model manually with
options snd-hda-intel model=<model>
Unfortunately, finding the correct sound card model can take a little guess work. I took me several tries to find the sound card model that would detect the headphones correctly.
This link gives a list of sound card model: http://ubuntuforums.org/showthread.php?t=1043568
More information can be found on the Ubuntu Wiki.