You could find your answer there :
http://ubuntuforums.org/showthread.php?t=789578
Appendix C
** Changed in: ubuntu
Status: New = Invalid
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no sound in games and youtube
https://bugs.launchpad.net/bugs/459189
You received this bug notification because you are a member of Ubuntu
Bugs,
Oh, sound is working after I raised PCM volume in KMix. However, I
wonder why for some apps I have to use PCM slider and for some other
another one?
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no sound in games and youtube
https://bugs.launchpad.net/bugs/459189
You received this bug notification because you are a member of Ubuntu
Bugs,
