STUFF MENTIONED IN Yoooge Book One

Noise Cancellation Headphones

From Yoooge Book One - "You can experience a similar phenomena when using noise cancellation headphones. If you wear noise cancellation headphones on an aircraft, the electronics in the headphones record the outside jet aircraft noise (+ve aspect) and then instantly plays that noise back to you upside down (-ve aspect) in the headset earpieces. When the noise of the aircraft combines with the equal and opposite noise in your headset the two opposing soundwaves cancel each other out to nothingness and the end result is complete silence in your headphones"