Inside the world's quietest room

Anechoic chambers are pretty damn awesome. Basically, they're rooms designed to be sound-proofed against outside noise, while, inside, sound is prevented from bouncing off the walls. There's no echo. There's a number of ways you can build this, but one system at the University of Salford in England, is actually a room within a room, with the innermost chamber actually mounted on springs, rather than the floor of the outer room.

Anechoic chambers are often used to test out audio equipment or to get accurate audio measurements on systems that are supposed to operate very quietly.

Minnesota Public Radio recently went inside the room that holds the title for world's quietest—an anechoic chamber at Orfield Laboratories in Minneapolis.

To get into the anechoic chamber, you go through two bank vault-like doors. The floor in the room is mesh like a trampoline so there's nothing on the floor for the sound to bounce off of. The walls are lined with sound-proofing wedges that are a meter long so they absorb the sound.

...A typical quiet room you sleep in at night measures about 30 decibels. A normal conversation is about 60 decibels. This room has been measured at -9 decibels.

Listen to the rest of the story at Minnesota Public Radio's website.

Read about the history of anechoic chambers.

Image: Photo of an anechoic chamber taken at the Kyushu Institute of Design's anechoic chamber by Alexis Glass. Free to use under GDFL.


  1. -9 decibels you say? Would that Orfield Laboratories had hosted the Republican Primary debates. 

  2. That room should be rentable. I would really like to just scream at the top of my lungs sometimes.

  3. After the 1974 energy crisis, my forward-thinking father started a branch of his construction company dedicated to insulation installation. Our primary material was blown-in loose cellulose, but for industrial spaces that didn’t have wall cavities, we mixed the cellulose with a glue and pressure-sprayed it onto the walls.

    Around that time, we moved into a house that had a interior powder room located right between the kitchen and family rooms. To gain a little sound privacy, my dad sprayed the walls and ceiling with the the cellulose. Worked better than expected; it was like walking into a dim, grey, fuzzy womb, silent and calm. It was the most popular room in our house.

  4. I’ve been in the movie theater at the Dolby Labs in San Francisco.  It has a similar setup (on springs, massive counter-weighted doors, etc).  These guys know sound so the experience is pretty awesome.  Alone in the room with the doors closed you hear the blood rushing through your ears (at least I do). 

    I’ve had the same experience being alone and still in a dry cave deep underground.  Combined with having the lights off, it is definitely some serious sensory deprivation. 

  5. In 2009 Stephen Fry visited the NPL, the National Physical Laboratory, which has an anechoic chamber and its opposite, a parabolic chamber that’s perfectly echoy, reflecting all sound waves back to the same point. He popped a balloon in them both and recorded how it sounded.

    A fantastic demonstration of just how awesome anechoic chambers are.

  6. I remember being taken to the anechoic chamber at the university where my dad worked when I was a kid. It totally freaked me out and spooked me!

  7. Could someone explain the “-9 decibels” figure? I wasn’t aware that the decibel scale could be negative. Is there any chance it’s supposed to be “~9 decibels”?

    1. Sure.

      Zero decibels is the quietest sound that can be heard, referred to as the “threshold of hearing”. It is anchored to human perception.

      The scale is logarithmic.

      Every 10dB change represents a factor of 2 in the loudness of the sound.

      So a negative 9 (-9) dB sound pressure level would mean that the sound level is just a bit more than 1/2 the loudness of the quietest thing humans can hear.

      1. I munged up loudness vs power. 

        10dB change = 10x in power

        10dB change = 2x in “loudness”

        (Thanks for the correction. I edited my original to loudness.)

  8. Oh, man, trying to sleep in a room that quiet would drive me batty!  I need a fan going, at least, to quiet the rushing blood in my ears, and racing thoughts.

  9. Another note on the Dolby location. The degree of isolation is even more amazing when you consider they’re right next to a major freeway artery and its attendant noise.

  10. I once went to a talk at the Bristol University Institute for Nanotech and Quantum Information, which is also billed as ‘the quietest room in the world’, but sort of in a different way. Because any very small vibration in the air or ground can utterly mess up a nanotech experiment, they’ve gone to extraordinary lengths to make sure their facilities are the quietest in terms of outside vibration getting in. 

    Take a look at their site. It’s pretty great.

    So… do we need to get Guinness involved here? In the immortal words of Harry Hill: “Fight!”

  11. When I worked for Eastman Kodak, I went into a soundproof room used to test Ektaprint photocopiers a few times.  It’s very hard to describe total silence; it’s disconcerting and a little creepy to hear nothing but perhaps your own heartbeat.

  12.  Visited the anechoic chamber at Notre Dame once, can corroborate the weirdness of the experience. Conversation required pointing my head in the right direction to hear the other person, otherwise all I could hear was the blood in my own ears. I’m not one to go for claustrophobia but that chamber did it for me.

  13. Here’s a thought experiment for ya…
    Let’s say that you live in Taos, New Mexico, and the Taos Hum is driving you crazy, also (for the sake of argument) let’s say that the Taos Hum is REAL, low frequency noise, not a mental abberation. Most people cannot hear it, but it is real, recordable infrasonic noise. And you can’t sleep BECAUSE of the noise/rumble. Also, for some reason, the noise is quieter OUTSIDE your house than inside, probably the fact that the building acts like a speaker as the sound travels through the air.

    How could you design an anechoic chamber to block low frequency sound with its long wavelengths? And is the anechoic chamber in the picture REALLY quiet, or are low frequencies not considered when describing something as “quiet”?

    I’m really curious how to build one of these for very low frequencies, or is it even possible? You know, for my “thought” experiment.

    1. I don’t know how to build a room that effectively blocks low frequencies, but noise cancellation devices are most effective for these kind of slow-changing, lower frequency sound.

  14. When I was a grad student in the UCLA physics department, I sometimes TA’d the acoustics class for undergraduates. This task garnered me to key to the formerly glorious UCLA acoustics labs, now in complete disrepair and disuse. Sad to see what shape it was in. But it was neat to be able to get into the old anechoic chamber. This one was a little different, it was one very large room, with acoustic dampening on all sides. The “floor” was actually a layer of chicken wire about 12 feet above the real floor. Definitely disconcerting the first time you walked out onto it. Unfortunately, the large ceiling lights are going out, one by one, and no one ever replaces them. The only contents are, for whatever reason, are two guitars and a small amp that have been there as long as anyone can remember.

  15. That photo looked so familiar. It took me a minute to realize it was mine, though :)  I miss time spent in the anechoic chamber. Being in there, you could see how experiences like that might inspire people to go much further (thinking Altered States, I guess) in exploring sensory deprivation. It’s just sound – you might that losing the early reflections reverberations of one’s environment would be a simple matter – but the disconnection feels quite physical and a lot more complete than (I, anyway) expected. Unfortunately you get used to it after a while.

  16. I got to go inside the anechoic chamber at GE’s labs in Fort Wayne several years ago. I could hear the blood flowing through my head. I have a little minor case of tinnitus, not enough to notice most of the time. Inside the chamber, it literally became painful. I couldn’t stay inside very long. The coolest part of the tour was when the engineer showing us around was talking to us inside the chamber, then kept talking while he turned his back to us. We couldn’t hear him anymore, even though he was still talking. Very cool.

  17. Reading the history article is like time-traveling back to the 1950’s: “computers used to require a large building and cost millions, but the new ENIAC fits in a mere large room and costs only 300K!!!!” 

    Given that home sound disturbance is a big problem and so a big potential market, is there some inherent physics-related reason why we don’t already have nano-scale anechoic wallpaper, or noise-cancelling loudspeakers that do the whole room and not just your head?

    I’d really like to know…

    1. I’d think that a good reason for not doing active noise on whole rooms (other than it being difficult and expensive for multiple users in large 3d spaces) is that the electricity bills would be high, and like an aircon that lowers the temperature in the room while warming up the outside, ubiquitous open-air ANC would aggravate the problem of noise pollution outside of the small oases in which the ANC was being applied.

      1. So much for that… thanks.  

        Silencio, the hugely popular noise-suppression band. In concert they’re awesome…

  18. It is rentable!  One year during the Seward art fair my husband did a reading at Orfield in one of their recording studios, with the single best microphone I have ever heard.  He didn’t sound amplified at all, just loud enough.  They brought a group of us into the chamber and I couldn’t believe how loud my body was, I could hear my hair creaking.

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