LOL!! ~ I think this device sounds kinda funny. But as mentioned above, it seems it would also pick up the background noises and drive the listener insane.
Honestly I have never been much interested in eavesdropping but then again have said a few times, "wish I could be a fly on the wall to hear what's said".
Ok, if I ever have one of these devices to give me "super powers" then I want xray vision glasses and a flying cape to go along with it!! Can you all say "SUPERMAN".