Orfield Laboratories in South Minneapolis is the home of a space that was once dubbed “the quietest place on earth” by Guinness World Records. (As of 2015, that title now belongs to a quiet room developed by Microsoft in Washington state). The lab is called an anechoic chamber, meaning there is no echo as the room absorbs 99.99 percent of sound. It is used by various manufacturers to test product volume and sound quality—and it can also drive a person mad.

A typical quiet bedroom at night measures about 30 decibels; this chamber measures at -9 decibels. It is made of 3.3-foot-thick fiberglass acoustic wedges and double walls of insulated steel and foot-thick concrete.

Manufacturers use the lab for product testing and development. Companies like Harley Davidson use the lab to create quieter bikes that still sound like a Harley, for instance. Other products like LED displays are tested to make sure their volume is not too loud. NASA, in fact, uses a similar lab to test its astronauts, given that space is like one giant anechoic chamber, explains Steven Orfield, president of Orfield Labs.

Members of the public must book a tour to visit the room, and are only allowed in for a short, supervised stay. According to the lab’s website, only members of the media are permitted to stay in the chamber alone for prolonged periods of time. One reporter lasted up to 45 minutes, and most people leave after half that time, tortured by the eerie sounds of their own body. “In the anechoic chamber, you become the sound,” says Orfield.

In the absence of outside noise, it is the presence of maddening silence to which the ears adapt. As ears adapt to silence, the sounds of your heartbeat, stomach, and lungs are your only reference, and it can be a disorienting experience.

Orfield explains that the only way to stay in the room for an extended period of time is to sit down. A person’s orientation is largely secured by the sounds made when walking or standing, and as those sound cues are taken away, perception becomes skewed, and balance and movement become almost impossible feats.