I guess I am guilty of taking this topic off tangent. But I wanted to make a point that there are certain risks that you take on when enjoying fruits of modern science. And you may not know what you are exposed to until many years later. And even then, it is awfully hard to give up certain things. It doesn't hurt to think about those things once a while. By the way, BT signal is narrow but it can be quite strong. Those neurosurgeons should use wired headphones.