Imagine a place so quiet you can hear your heart beating or your eyes blinking. That place exists at Orfield Laboratories in Minneapolis, Minnesota. It’s what’s known as an anechoic chamber, a room designed to silence any echoes—and this particular one holds the record for the quietest place on Earth. The room is in a steel box suspended by springs inside another steel box, surrounded by concrete walls. Inside the chamber, brown fiberglass wedges cover every surface to absorb sound waves. It’s so silent that noise is measured in negative decibels, meaning it’s below the threshold of human hearing. Companies use the chamber to test product noise levels—from refrigerators to Harley-Davidson motorcycles—and NASA uses it to train astronauts. Visitors can book sessions starting at $75, but be forewarned: The experience can be disorienting. People often struggle with balance because we rely on ambient sound to orient ourselves. And you might start hearing the blood pumping through your veins. “In the anechoic chamber,” Steven Orfield, the lab’s founder, told the Daily Mail, “you become the sound.”