Microsoft scientists hold up a sign documenting their world record in the anechoic chamber

Quietest space on earth record broken by Microsoft

Microsoft’s anechoic chamber has broken the world record for the quietest place on earth.

The standing record of minus 13 dB(A) was recently broken by staff at the company’s Redmond campus in Washington after the chamber proved to have an ambient background noise level as low as minus 20 dB(A).

The room is used by Microsoft as an acoustic testing lab for a number of its products including speakers, microphones and its voice assistant Cortana.

When testing its voice assistant, the team will rapidly fire questions at Cortana while sound engineers introduce canned, real world background noises into the room to stress the vocal recognition software.

The research space actually consists of a series of anechoic chambers, the largest of which has its own foundations and sits atop springs to minimise any outside noise.

To break the record, tests were carried out with assistance from measurement expert, Brüel & Kjær, which provided Microsoft with instrumentation and analysis software to assess the room.

Brüel & Kjær used a special, two-microphone coherent power measurement technique to achieve the extremely low ambient noise level measurement.

A speech and hearing scientist at Microsoft, Dr Hundraj Gopal, said: “Anechoic chambers are special rooms containing sound-absorbing and sound attenuating material in the walls, ceiling and floor that are designed to absorb 99.99 per cent of the sound, ensuring the space is free from echoes.

“Microsoft uses these super-quiet acoustically-controlled chambers to test products such as Surface tablets, HoloLens, etc., to make sure that sounds generated by the devices themselves during use, are as quiet as possible.”

The ‘Brownian motion’, which is the movement of particles in a liquid or gas, is thought by mathematicians to be the quietest sound and measures minus 23 dB(A), just three decibels lower than Microsoft’s chamber. Total silence is achieved in a vacuum such as space.

In March, it was reported that Microsoft was developing an advanced version of Cortana with a new artificial intelligence engine know as Einstein.

The company included the voice assistant in its latest version of its operating system, Windows 10.

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