Ear Force X2 - FAQs
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Setup - Players can hear me, I can hear them, BUT I cannot hear MYSELF 
Q:  I've set up an Ear Force X2 headphone/mic for my XBOX360 wireless and game
    audio and chat from other players is fine in the headphones. I cannot hear
    my own voice however through the headphones even though other XBOX Live 
    COD2 players can hear my comments.

A:  The stock xBox360 mono headphone is not supposed to carry your own voice
    either. This is how the xBox was designed to work.
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