You have hearing problems then my friend. I wear ASTRO A40's and can hear the sound of the other player switching weapons, foot steps, shoulder charge (sound plays either through left or right) same goes for shadestep, when someones going invis, I could even hear people shooting out their bullets to final round in trials all the way in their spawn. I love inferno for that reason, listening to all the sounds and using your eyes, you're more focused too.