Offices and tiny apartments could be transformed by the work of Boston University researchers, who recently unveiled an "acoustic metamaterial" that blocks all sound.

A team of Boston University researchers recently stuck a loudspeaker into one end of a PVC pipe. They cranked it up loud. What did they hear? Nothing.

How was this possible? Did they block the other end of the pipe with noise canceling foams or a chunk of concrete? No, nothing of the sort. The pipe was actually left open save for a small, 3D-printed ring placed around the rim. That ring cut 94% of the sound blasting from the speaker, enough to make it inaudible to the human ear.

The mathematically designed, 3D-printed acoustic metamaterial is shaped in such a way that it sends incoming sounds back to where they came from. [Photo: Cydney Scott/Boston University]

Dubbed an "acoustic meta-material," the ring was printed from a mathematically modeled design, shaped in such a way that it can catch certain frequencies passing through the air and reflect them back toward their source. Typical acoustic paneling works differently, absorbing sound and turning the vibrations into heat. But what's particularly trippy is that this muffler is completely open. Air and light can travel through it–just sound cannot.