I'm having a hard time figuring out if you're talking about the phone itself, or you're using headphones.
If you're talking abut the phone itself, then I don't really know...
Maybe you can see a audio out partial wakelocks in bbs? I'm guessing it's something that hasn't shut the speaker off and is still running in the background.
My phone doesn't have this problem lol I hear nothing and I'm on AT&T version as well.
Sent from my LG-D800 using Tapatalk