Sounds of Silence


29 January 2018

In our third instalment to promote relaxation, along with tools and techniques that may aid sleep, we explore the power of different sound frequencies. By frequency, we mean the rainbow that is the colour of noise, referring to the spectral density of a noise signal. All the colours of noise have significantly different properties and as audio signals they will sound different to human ears. These are defined using different colour names, commonly known as white, pink, brown, blue, violet and grey noise*.

For the purposes of these sleep and relaxation aids, we have focused on white, pink and brown noise.

White noise has been proven to help us sleep by making us less conscious of our immediate environment, which allows our mind to relax in a similar way to meditation. In fact, Ancient Jewish texts have described a dripping water white noise machine to aid sleep as a means to aid sleep*.

Pink noise can be likened to the sound frequency of white noise , but with added bass.

And finally, brown noise is a frequency which is even deeper than pink noise. So deep in fact, that it can often be missed completely.

You may already know or notice which colours of noise aid your relaxation, which if that is the case head straight to sound you know, otherwise give all three a try and find out for yourself.

To help you along, ambient recordings have been taken of natural surroundings that have similar frequencies to white, pink and brown noise. Just use the slider moving from right to left and vice versa and this will guide your preference.

For example, if pink noise, then you can move the sound slider between raw, London traffic noise or a pure, pink noise sound or a mixture of both.


White-noise works by reducing the difference between background sounds and a 'peak' sound, like a door slamming, giving you a better chance to sleep through it undisturbed. We have associated it with the sounds heard on Trwyn Llanbedrog beach in North Wales. Typically, white-noise is a constant ‘shhh’ sound, which is a bright noisy stew of frequencies, produced by combining sounds of all frequencies together. These frequencies are likened to waves hissing against the shore on the beach – a sound very often associated with restfulness.



A busy London overpass has been matched with pink noise frequencies which is like white noise but with the bass cranked up. As well as the rumble of traffic, rainstorms can also have a pink noise frequency. The 24-hour activity of modern cities feels at odds with our need to sleep – but what if we could take that hustle and bustle and use it to help us relax?



Kielder Forest, being the quietest place in the UK, doesn’t at first seem to have many sounds. But, the sound of wind blowing through the trees can be likened to the frequency of brown noise. Brown noise is an even deeper version of pink noise; a deep, rolling rumble that can often go unnoticed.


Once you have identified your perfect sound, listen with headphones in and the sound turned up for the best effect.



Further Reading: Auditory Closed-Loop Stimulation of the Sleep Slow Oscillation Enhances Memory