When you turn on the Force Feedback function, the headphones catch the low frequency signals. Then, via transducers in the actual earpieces somewhere, they turn those signals into vibrations. It is like strapping subwoofers to your head. The bass makes the things shake. Now, lets look at the force feedback for a second.
Lets use a wheel, or a joystick for comparison.
When you are driving, you feel the road conditions in your controller. Slick, cobblestone, power slide, you feel all that. I used these headphones for a couple things. It gives me the impression of a winamp plugin, kinda. That is what it feels like.