Now that is old HOAX ! Color on the map is combination of depth and 3d shading. It has nothing to do with sound propagation. I really wonder where this idea came from.
As for the second wave, it should not work like this, since the reciever can't tell bottom bounce from direct reflection. Bottom bounces should just create false contact little far away from the real contacts.
Anyway I have never seen anything like 'second way'
