It's called an anechoic chamber. Sound diffuses by hitting the walls so much that no echo is perceived. There is no floor also to prevent further sound distribution, so you actually float in mid air. It is made by Orfield Labs, and has a -9 decibels less room tone than the average so called "quiet" room, which is about 30 decibels of sound pressure loudness. An amplitude of 6 decibels raises or lowers the sounds by a double. It is made up of 3.3-foot-thick fiberglass acoustic wedges, double walls of insulated steel and foot-thick concrete.
