If I remember it correctly, you can set your audio-options in-game to play from first-person or third-person direction.
Let's see if I can elaborate on that...
If you're using third-person view (as probably 99% of the playerbase except me does) every sound-effect would be played in your headphones as if you were really where your "avatar" is in the game world.
OR!
If your audio-settings are set the other way around the sounds would play as if your headphones are placed where the "camera" is.
Easiest way to find out is to zoom out all the way you can and start running.
Listen to your own steps.
Now zoom in into first-person view.
If the sounds of your steps increased in volume you have set your audio-options wrong and should select or deselect (whichever is appropriate) this setting in the in-game audio options tab.
I don't remember which setting is used by default but I'm personally using the one which enables me to hear everything up loud in 3rd-person view (which I use in combat).
I hope you understand what the he*k I'm talking about and that you find the above helpful