Sound Invisibility

Fantastically-interesting project detailed at Physics WorldMartin Wegener, Nicolas Stenger, and Manfred Wilhelm of the Karlsruhe Institute of Technology in Germany built the device above which can cloak objects from sound waves.  The rings around the center are filled with soft plastic and an object to be cloaked is placed in the center hole.  Because of the design of the rings, sound waves approaching the object are bent and re-emerge on the other side exactly as they came in.  There are no acoustic reflections off the object whatsoever.

Via: Physics World (thanks Stephen Shingler)