The Wall of Sound Meets its Match - Sono - An Acoustical Wall Filter Idea

Austrian industrial designer Rudolf Stefanich has created a concept device that is capable of filtering outside noise from entering your room.

Called ‘Sono’, it transforms any window into an “active noise canceling system”, allowing users to eliminate and filter the sounds that pass through their windows.

By turning a knob, the device filters out disruptive noises like car horns and construction works, but allows pleasant sounds like birds chirping or the sound of the wind through.
“In our loud and busy world, a moment of silence has become a scarce and almost luxurious experience,” said Stefanich. “Sono lets you reclaim that silence for your home.” (more)

FutureWatch - The same concept could be used to prevent eavesdropping via acoustical leakage from rooms.