Orfield Laboratories’ ‘anechoic chamber’ in the U.S is 99.99% sound absorbent. The longest that anyone has survived here is just 45 minutes.
The room holds the Guinness World Record for the world’s quietest place, but stay there too long and you may start hallucinating. It achieves its ultra-quietness by virtue of 3.3-foot-thick fiberglass acoustic wedges, double walls of insulated steel and foot-thick concrete. The chamber is used by a multitude of manufacturers, which test how loud their products are.