The quietest place in the world is a chamber at Microsoft's headquarters.
A desert landscape or deep forest may seem like a good candidate for the quietest place on Earth. But to experience true quiet — thunderous-thump-of-your-heartbeat quiet — requires a lot more technology than you’ll find in nature, so it makes sense that one of the world’s largest tech companies is host to the ultimate quiet room. Tucked inside Building 87 in Microsoft’s Redmond, Washington, campus is an anechoic (“free from echo”) chamber specifically designed to eliminate outside noise in all its forms. Microsoft didn’t build the room to earn a Guinness record for the world’s quietest place, of course; the chamber is used in part to test how much ambient noise the company’s devices emit (think the subtle hum of a monitor or buzz of a charging cable).
The anechoic chamber in Building 87 was constructed with six layers of concrete and steel, which all rest on damping springs in the floor to eliminate nearby vibrations. Fiberglass wedges cover the walls and ceiling, designed so that sound waves get trapped in their purposeful geometry and dissipate. The result is a room that is -20.35 decibels. Yes, negative. Any sound pressure that dips below the threshold for human hearing is represented as negative decibels. For comparison, the sound of breathing has been measured at 10 decibels, while the sound of air molecules colliding in a gas or liquid (known as Brownian motion) is -23 decibels. (At the other end of the extreme, a rock concert may be 110 decibels.) In Microsoft’s chamber, the subtle sounds of the human body — breath, circulation, digestion, heartbeat, joint movement — become undeniably audible, and the rustle of clothes sounds like the roar of the ocean. In other words, inside this anechoic chamber, your body creates its own soundtrack.
On October 14, 1947, Chuck Yeager, then piloting the experimental X-1 rocket plane, became the first human to travel at the speed of sound (defined as around 767 miles per hour at 68°F). But Yeager wasn’t the first human to break the sound barrier at all. Humans have been breaking it since at least Roman times. Every crack of a whip is actually a sonic boom, a shockwave that’s created as a part of the whip travels faster than the speed of sound. Researchers long thought the tip of the whip produced the sonic boom, but 2002 research showed that it’s actually produced by a loop that travels along the whip as it's cracked, moving faster and faster until it breaks the sound barrier. (For the record, cotton bed sheets have also been shown to create a sonic boom when snapped — although we don’t suggest trying this at home.)
