Microsoft's Redmond, Washington campus is the home of what the Guinness World Record organization has named as the quietest room on Earth. The company has put the spotlight on that anechoic chamber in Building 87 in an interactive feature story and video.
The chamber contains wedges in the walls that are designed to absorb sound. The room has been recorded to have a sound as low as -20dB, For comparison's sake, that is just above what scientists consider to be the quietest anything can reach with Brownian motion, which is the sound that is made by the movement of particles in a gas or liquid at -23dB.
So what are these super-quiet chambers used for at Microsoft? Hardware like the Surface tablets are tested inside the room to make sure that sounds that are generated by things as simple as its display are as quiet as possible.