What you have to do?
In this demonstration, you will have to pay close attention to whether the sounds come from, the left or the right. The demonstration works best on headphones with the left and right channels in place (usually marked with an L and an R at the headset). You can also use stereo loudspeakers that are at least at a 45 degree angle left and right of your head. If you experience the illusion, you will perceive the sounds as coming from different places depending on whether or not you watch the screen.