Photo: Steven Orfield/Orfield Labs
If you think that loud noises drive you mad, try this quiet room for a change.
The anechoic chamber at Orfield Laboratories in South Minneapolis, certified as the quietest place on Earth by the Guinness World Records, is so quiet that the longest anyone has survived being in there is just 45 minutes:
‘When it’s quiet, ears will adapt. The quieter the room, the more things you hear. You'll hear your heart beating, sometimes you can hear your lungs, hear your stomach gurgling loudly.
‘In the anechoic chamber, you become the sound.’
And this is a very disorientating experience. Mr Orfield explained that it’s so disconcerting that sitting down is a must.
He said: ‘How you orient yourself is through sounds you hear when you walk. In the anechnoic chamber, you don't have any cues. You take away the perceptual cues that allow you to balance and manoeuvre. If you're in there for half an hour, you have to be in a chair.’
That's right Ray, the wedges will measure out to being 1/4 of the wavelength of the lowest frequency they can absorb. Bellow that, the sound will reflect (which is why you can start to hear your own heartbeat, breathing etc.).
I can't stand it when it's too quiet when I'm trying to get to sleep b/c I hate hearing my heart beat in my ears.
The chamber was in a huge brick cube mounted on rubber blocks. Pretty neat.
Yikes.
For starters, I don't see any figures here. And what those figure would reveal is not how quiet something is, but at what frequencies and at what times it is quiet.
The efficiency of an anechoic chamber is expressed by the lowest frequency at a given T-60 (T-Sub-60) measurement. That is, T-60 is the (T)time it takes for a given frequency to drop by 60 dB .
Example, if you put a blast of 120 dB white noise through a speaker in the middle of a basketball gym, and cut the signal, how long will the 1K frequency reverberate and echo before it's strength is 60 dB lower than when you turned off the sound source?
It's fairly easy to cut the reverberations (i.e. make something anechoic) of, say, a 10K Hz or 5K Hz tone. Making something anechoic at 175 Hz or less becomes MUCH more problematic.
I've worked in anechoic chambers that are, in the parlance of the industry, "dead" down to ~90 Hz. Actually, I've spent hours in them, and I don't know what all this stuff about "ooo-aaa, you can only spend 25 minutes in there, scary!!' is.
That said, I got a fan on now in my apt and love the white noise.