Do they really work as advertised in this video?
http://www.youtube.com/watch?v=qDWvW6iGWWE
Because if so, that's pretty incredible. Another thing I've wondered - what happens when these things run out of batteries? Do they just revert to a regular passive earmuff? Do they maintain their maximum sound reduction level in that state?
They're quite pricey, but they seem kind of miraculous.