Sound after iOs8 Upgrade
I have the same issue... sound only coming from left ear bud... in car (using Blue Tooth)... sound only coming out of right speaker... only started after iOs8 upgrade.
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I finally found the cause... Under Settings, General, Accessibility, Phone Noise Cancellation... was set all the way to the L. I put it back to the middle and all sound back

I've never changed that setting... not sure why it got changed after the upgrade.