Sometimes, one just needs a bit of peace and quiet. Not for serenity (well, that too), but for scientific research. If you want to measure how loud a consumer product is — say, that of a cell phone’s ring or the hum of a dishwasher — you are better off doing so in an environment with little to no ambient noise. So many organizations — Apple, Microsoft, and the U.S. military to name a few — have built special rooms , called anechoic (read as “an-echoic,” as in “echo free”) chambers, to create such conditions.

Minneapolis, Minnesota-based Orfield Laboratories has one, too. And they rent it out so that others can test their products, much like Apple and others do in their own chambers. But Orfield does something additional: they let visitors sit in the room, alone and in the dark, to see how long they can last without going mad.

According to Minnesota Public Radio, the typical quiet room — such as your bedroom late at night — has an ambient noise level of about 30 decibels, caused by the rustling of sheets, the hum of the air conditioner, and similar sources of white noise. Orfield’s anechoic chamber has a noise level of -9 decibels — yes, negative nine. According to Guinness World Records, it is the world’s quietest room. The silence-producing design, according to the Deccan Chronicle and seen above, features a “trampoline”-like mesh floor, which prevents sounds from reflecting off of it; and walls with one meter-long pieces of soundproofing protruding outward, which absorb sound.

A trip inside may seem like a get-away from the tribulations of the rest of the world, but as Orfield Laboratories President Steve Orfield notes, nothing could be further from the truth. He explained why to Minnesota Public Radio: “When you sit in any rooms a person normally sits in, you hear the sound and all its reflections. When you go into an anechoic chamber, there are zero reflections. So if you listen to me talk and hear my voice, you’re hearing my voice exactly. And if I turn around and talk, the only thing you’ll hear is the sound bending around my head.” The body adapts to the massive sensory deprivation by finding whatever it can latch onto — even its own noises. Quite literally, the mind starts focusing on the sounds of one’s own heart beating and lungs expanding. It is enough to drive almost all people to hallucinate.

Orfield himself can only last about 30 minutes in the room before listening to his body parts (including, and especially, an artificial heart valve); it’s more than he can handle. But perhaps the word “only” there is improperly used. As reported by the Daily Mail, the longest anyone has lasted is 45 minutes.

Bonus fact : Want to make someone feel terrible? Say nothing for four seconds. According to researchers in Holland (per TIME), that’s how long it takes for the listener’s brain to take your silence as a rejection of his or her last statement.

From the Archives: Small, Hot, and Loud: It’s small enough to fit in your hand, and can make noises which are louder than a sonic boom.

Related: The Relaxman Relaxation Capsule, which, per the product description, is “completely heat, light, and sound proof, providing total isolation.” At nearly $50,000, you probably won’t be buying it. Five reviews, all obviously fake (but worth reading).