White noise is what you get when you combine the complete audible spectrum into one incorporate sound. The name derives from white light, made of all the different colours (frequencies) of the visual spectrum. In the same way that a prism or a rainbow separates white light back into its component colours, white noise is a combination of all the different frequencies of sound. You can think of white noise as 20,000 tones all playing at the same time.

White noise is used extensively in electronic and synthesized music. It can be used directly or as an input for a filter to create other types of noise signals. Direct applications include synthesis of instruments such as cymbals which have a high noise ratio in their frequency band.

It is used to generate test tones for concert and performance venues. Short bursts of white noise are sent through a PA system which are then monitored with microphones and spectral analysis so an engineer can tell if the acoustics of the building naturally boost or cut any frequencies. It’s also used for frequency response testing of amplifiers and signal processors. The genre of noise metal also benefits extensively from copious amounts of white noise – a type of music you can only love like you would an abusive husband. Hella, a band hard to get into but harder to get out of.

It’s said that white noise can help aid both rest and concentration, as it can mask irritating noises such as tinnitus. It can sound like a rushing waterfall or wind blowing through trees. Devices known as sleep aids do not produce actual white noise, which has a harsh sound, but pink noise in which power rolls off at higher frequencies. White noise is frequently used to mask other sounds since the brain can not differentiate between the thousands of frequencies and the “voice next door”. Masking devices are often used to protect privacy by screening distant conversations, for example, in a psychiatrists waiting room.