Step inside the quietest room in the world

Microsoft has created the quietest room on the planet.

No, really — the company just won the Guinness World Record for it

So how do you make a super-silent room, and why bother?

Step inside to find out…

Microsoft built its 'anechoic chambers' in its hardware lab, Building 87, on its campus in Redmond, Washington.

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Anechoic means 'echo-free.' The company actually has three chambers, each designed to completely absorb sound.

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Microsoft's Audio Lab team uses them to test its Surface tablets and digital personal assistant Cortana.

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To create an 'acoustically-controlled environment,' Microsoft specifically designed the walls, ceiling, and floor of the room with sound-absorbent wedges.

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Underneath the largest chamber, there's an entirely separate foundation from the rest of Building 87: The room sits atop springs.

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To keep outside noise out, there's an 'air gap' between the chamber and the rest of the building.

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That means that researchers have to step across a bridge to get into the chamber.

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Here's a peek at the wedged ceiling.

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A Gizmodo reporter who went into one of the chambers wrote that voices sounded clipped, because they lacked the barely perceptible echoes that normally accompany speech. 'My own voice sounded like it was having trouble coming out of my head,' Wilson Rothman wrote. 'For a moment, I felt genuine disorientation, like the light-headedness you can get with low blood sugar.'

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This is not the Gizmodo reporter in question.

Source.

To get a better idea of how quiet Microsoft's anechoic chamber is, here's the world's loudest sound:

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Theoretically, the *absolute* quietest sound is called 'Brownian motion':

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Microsoft's chamber is almost as silent as simply the sounds of air particles moving. 'We're at the edge of the limits of physics,' Microsoft says.

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For reference, normal conversation is about 60 decibels, compared to the anechoic chamber's -20 dB and the volcano's 170 dB.

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Besides just studying the 'sound of silence,' Microsoft will do things like measure the noise that comes out of an at-rest Surface tablet.

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Here's a researcher demonstrating how Microsoft also tested various noises associated with its tablets, like the sound of closing the stand on the back. 'We wanted to make sure we're making a product that *sounds* robust,' he says.

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The team also uses the chambers to test the Surface speakers and the Surface microphone. It has a mannequin that rapid-fires questions to Cortana while engineers play a variety of background noises meant to trip the personal assistant up.

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Who are these engineers? They range from psycho-acousticians to fibre optics experts.

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The team knew their anechoic chambers were state of the art, so they decided to try to prove how quiet they were.

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When Microsoft realised they had completely blown the previous world-record (-13 dB) for quietest room out of the water...

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They celebrated with some brewskies.

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