Guinness World Records has officially ruled: an audio lab at Microsoft's headquarters in Redmond, Wash., is the quietest place in the world. Though Building 87 on the Microsoft campus is home to three anechoic, or "free from echo," chambers the company uses to test audio technology, the largest is "unimaginably quiet," testers say, per Science Alert. It helps that the room is covered in "wedges" made of sound-proofed material and built on springs to cut down on vibrations. But how exactly do you decide which is the quietest place on the planet? It comes down to a sound measurement. The silence inside the chamber measures -20.6 dbA (decibels A-weighted), compared to -13 recorded at the Anechoic Test Chamber at Orfield Laboratories in Minneapolis back in 2012.
A second test in the chamber—which Microsoft calls the place "where sound goes to die," per Fortune—returned a slightly less impressive -20.1 reading, but both results surpassed even the expectations of Microsoft, which had expected about -16, according to Guinness. So what does -20.6 dbA sound like? Humans can't actually hear anything below zero decibels, but "to give you a rough idea, the Brownian motion—that is, a random air particle in space—is around -23 dBA. You can't get any quieter because that's just the air particles moving," an Microsoft engineer explains in a video. "We are on the edge of what [are] the limits of physics." Thinking Building 87 would be a great place to take a nap? Sadly, you're probably out of luck. Engineers are busy using its anechoic chambers to train the Cortana digital assistant to better handle audio inputs and outputs. (Listen closely, and you can hear California's drought.)