In Building 87 on Microsoft’s Redmond campus, you’ll find an anechoic chamber—a space designed to absorb and isolate sound—built by Eckel Industries and certified by the Guinness Book of World Records as the quietest place on Earth in 2015. The chamber is so effective that the ambient level of noise inside is actually -20.6 decibels. To put that in perspective, the ambient sound level of a person in a very quiet room breathing as a resting rate is around 10 decibels.