Recently, Matt was given the opportunity to tour the anechoic chamber in Building 87 on Microsoft’s campus in nearby Redmond, WA, deemed the quietest place on earth by Guinness World records in October 2015. The tour, led by Gopal Gopal, Principal Human Factors Engineer at Microsoft’s Audio Lab, left quite the impression on Matt, both literally and figuratively.
The Building 87 anechoic chamber is used to measure noise associated with products under development at Microsoft. As such, a quiet environment is imperative to obtaining accurate data on which to base engineering decisions. To frame the discussion around ‘quiet’, it’s important to understand that the typical threshold of hearing is approximately 0 dBA. The noise of random motion of air particles, or Brownian motion, comes in at -23 dBA, the quietest theoretical noise level. Before Microsoft set the record, the quietest place on earth was in a similar facility at Orfield Laboratories in Minneapolis, MN, which had a noise level of -13 dBA. Microsoft bested this record considerably, inching quite close to the Brownian motion minimum, and achieved an exciting -20.6 dBA.
Matt learned that our vestibular system, the system based on our inner ears that regulates balance, can be significantly impacted by visiting quiet environments such as this. Our ears are typically exposed to noise levels of between 30-70 dBA constantly throughout the day. We hardly think of many of the noise sources we’re exposed to – ambient noise due to HVAC, background music in the coffee shop or conversations in an adjacent cubicle or office all play a role – but it’s rare that these levels get much quieter. Walking into a space that has a background noise level of -20 dBA is in stark contrast to the typical noise environment, and imparts significantly less pressure on the edge of our vestibular system, the ear drum. In this type of hyper-quiet environment, the recalibration of the vestibular system can cause disorientation or loss of balance.
When the lights were switched off in the space, Matt got dizzy and had trouble standing. Amazing! Acoustics directly affecting the inner workings of our body!
If you’d like to learn more, join Gopal Gopal on a tour of the anechoic chamber via YouTube here (https://www.youtube.com/watch?v=Cyqc_4ixV80).