An anechoic chamber is a room designed to stop reflections of either sound or electromagnetic waves. They are also often isolated from energy entering from their surroundings. This combination means that a person or detector exclusively hears direct sounds, such as their heartbeat or the cracking of bones. The chambers give the effect of being in a free field devoid of gravity.
Microsoft developed an anechoic chamber of its own. The specially constructed chamber is hidden in the depths of Building 87 at Microsoft’s headquarters in Redmond, Washington, where the firm’s hardware laboratories are based. The chamber currently holds the Guinness World Record for the world's quietest place. When the background noise level inside was measured at an ear-straining -20.6 decibels. Nobody on record has managed to stand in the world’s quietest room for a whole hour.