June 26, 2018

As a parent, you’ve probably come across the term ‘white noise’ when desperately seeking answers on how to get your baby to sleep. There are a plethora of ‘white noise’ producing devices available, marketed for their ability to create soothing sounds which are suppose to induce sleep. But what is this ‘white noise’ and is it really the best option for getting a baby to sleep?

What is White Noise?

Did you know that the gentle hum of a fan or air conditioner is commonly thought of as white noise but in actual fact, is pink, green, brown or blue noise? Audio technicians will tell you that these colours of noise contribute to the creation of relaxation music, mimicking sounds of nature and the noises around us (including human breathing or heart beats).

If I can get technical with you for a moment, this is how it is broken down. If you stay with me here, you’ll be amazed at how it all works.

Frequency (a sound wave's speed per second) and amplitude (size of the soundwave) combine to create the variety of sound colours we experience. For example, white noise operates at audible frequencies as does white (the colour) show with visible frequencies. Still with me?

Everyday noises are created by random sound waves (frequency and amplitude) and aren’t necessarily pleasant to the ear. Music, however is created by intervaled frequencies that are spaced in such a way to be pleasant to listen to.

The out of range radio noise is a well known white noise and is made up of equally powered frequencies firing all at once and mixed uniquely together that change all the time.

Other noise colours are created when more energy is concentrated at the high or the low end of the sound “spectrum” which changes the nature of the signal. When you turn up the bass on white noise, it becomes pink noise.

You may be aware that humans don’t hear all frequencies. We hear in octaves (removing everything in between). The octave doubles the frequency (and power). So with pink noise, the remaining frequencies found in white noise are removed so it doesn’t sound so harsh to our ears.

white and pink noise
Spectral analysis of white and pink noise, with frequency on the horizontal axis and power on the vertical axis (The Physics Hypertextbook)

In recent years, more awareness has arisen around pink noise and I am also starting to wonder if parents can utilise this knowledge to achieve an even deeper sleep as some health blogs are proposing. This one has a whale noise that sounds as pink as I have found thus far.

I've personally found success in branching away from a 'white noise' device on the occassion and experimenting with pink noise.

Here's a quick run down of other 'colour noises' which you can experiment with yourself to see which produces the best result for you and your baby. A quick search on YouTube and you'll find plenty of examples of what each of these sound like.

Brown noise - Is a ‘mature’ version of pink noise. It’s deeper, has more bass and its grumblier than pink.

Blue noise - Has energy at the top end of the spectrum. It’s the opposite to pink noise and to achieve it, frequency and power are increased at the same rate (ie. each octave has as much energy as the two octaves below it combined).

Grey noise - Sounds exactly the same at every frequency and is a lot like pink noise, calibrated to be sound balanced but there is no single example because every human perceives sound differently.

Other noises, although not officially recognised are Green, Orange and Violet
Green Noise where more energy is focused in the middle of the sound spectrum.

Orange Noise - Unpleasant array of disjointed noise like an “out of tune orchestra”

Violet - More intense than blue noise, with even more energy focused at the highest frequencies

Black - Silence

Oh yes, silence. How I miss you...