I've seen something like that on BBC Horizon. The idea was to give this to a blind person to help with navigation. BTW, I'd like to know if a single buzzer is

I've seen something like that on BBC Horizon. The idea was to give this to a blind person to help with navigation. BTW, I'd like to know if a single buzzer is enough for this purpose - vibrate stronger as the angle north gets smaller. I'm quite sure human would be able to quickly learn this. Or maybe a combination of two buzzers. BTW', I don't need to mention that I had similar idea to Indoor Atlas http://www.indooratlas.com/technology.html http://www.indooratlas.com/technology.html (but of course, ideas don't matter only execution)