The funny thing about these is that they don't really make you constantly aware of where north is. To answer that question you would have to concentrate on the vibration. What acutally happens is way cooler: You become subconsciously aware of the structure of the space surrounding you. This is something that everyone has to a leser extent i.e. you could point at the direction of various objects around you and tell me roughly how far away they are even without looking. When you have been wearing the belt for a few weeks you are able to do this even for objects that are not in you immediate vicinity. You get an actual feeling for the location of all kinds of things. Imagine having an accurate intuition for the location of your home town or the next highway exit! Another example: you could visit a city where you have never been before, wander around the streets without caring for where you go and then immediately find the shortest route back to where you started. And it would be about as hard for you as finding the way to the door of the room you're in right now.