The colours of noise explained: white, pink, brown, green and more
The colours of noise describe where the energy sits: white is even, pink falls 3 dB per octave, brown 6 dB. Here is what each sounds like and when to use it.
- What the colours mean: the colour of a noise describes how its energy is spread from low to high pitches, the same way colours of light describe a spread of wavelengths.
- The three exact ones: white noise has equal energy at every frequency, pink noise loses 3 dB per octave and brown noise loses 6 dB per octave.
- Blue, violet and grey: blue and violet noise tilt the other way, gaining 3 and 6 dB per octave, and grey noise is shaped to sound equally loud at every pitch to the human ear.
- Green and orange are informal: neither has a standard definition, and green noise usually means noise centred on the middle frequencies, around 500 Hz.
- For sleep, no colour is proven: a 2021 systematic review of 38 studies rated the evidence that steady noise improves sleep as very low quality.
Shimmr Binaural beats for meditation, sleep and focus Get Shimmr What are the colours of noise?
The colours of noise (in American spelling, the colors of noise) are names for how a sound’s energy is spread from low pitches to high ones. The idea is borrowed from light: white light mixes every colour equally, so noise that mixes every frequency equally is called white. Tilt the energy towards the low end and the noise gets “warmer”, like red light. Tilt it towards the high end and it gets “bluer”.
Every colour is still random noise with no melody or rhythm. What changes is the balance. That balance is measured in decibels (dB) per octave, where an octave is a doubling of pitch, for example from 500 Hz to 1,000 Hz. This guide gives you the whole map in one place. For the colours people use most, we link to a deeper article on each.
How many noise colours are there?
Six noise colours have exact technical definitions, and a few more are informal names. Here they are side by side:
| Colour | How the energy is spread | Sounds like |
|---|---|---|
| White | Equal at every frequency | Hiss, fan, radio static |
| Pink | Falls 3 dB per octave | Steady rain, wind in trees |
| Brown (or red) | Falls 6 dB per octave | Low rumble, distant waterfall |
| Blue | Rises 3 dB per octave | Thin, bright hiss |
| Violet | Rises 6 dB per octave | Very sharp, high hiss |
| Grey | Shaped to the ear’s loudness curve | Even at every pitch, to your ears |
| Green | Informal: centred around 500 Hz | Soft, “natural” whoosh |
| Orange | Informal: no standard definition | Varies by source |
Brown noise is not named after the colour. It comes from Brownian motion, the random drift of tiny particles described by the botanist Robert Brown. Blue and violet are used more by audio engineers than by sleepers, because their bright top end is tiring to listen to for long.
What does each noise colour sound like?
The lower the energy sits, the deeper and softer the noise sounds. White noise is the brightest of the common ones, because your ears are most sensitive to the higher middle frequencies where it has plenty of energy. Pink noise takes the edge off and sounds like rain. Brown noise sounds like a rumble heard through a wall.
If you want the difference between the two most popular colours in detail, read brown noise vs white noise. Green noise is the newest name and the least defined; we explain where it comes from in what is green noise.
Which noise colour is best for sleep?
No noise colour has been proven best for sleep, so choose the one you find easiest to ignore. A 2021 systematic review of 38 studies rated the evidence that steady noise improves sleep as very low quality. Results ranged from better sleep to worse sleep, and the authors noted that noise may also harm sleep and hearing.
What noise does well is mask. A door or a cough wakes you because it stands out against silence, and steady noise makes it stand out less. Deep sounds like traffic are masked best by brown noise. Higher sounds like voices are masked best by white or pink. Pink noise has its own research story, including lab studies with short pulses timed to brain waves, which we cover in pink noise for sleep.
Keep any noise well below normal conversation, which is about 60 dB, and let a timer fade it out once you are asleep.
Which noise colour is best for focus?
There is no proven best colour for focus, but brown noise is a popular choice. Its deep sound covers office hum without the brightness of white noise, which some people find tiring after an hour or two. If you need to block voices, white or pink usually works better.
People with ADHD often say brown noise helps them concentrate. The research behind that is small and mixed, and we go through it in brown noise for ADHD. A simple test: try one colour at low volume for 20 minutes, then switch and compare.
How do you choose a noise colour?
Pick by the job and by what feels comfortable. A quick guide:
- To cover voices or a TV: white or pink.
- To cover traffic or a low hum: brown.
- For a soft background while you fall asleep: pink or brown.
- For something closer to nature: green or pink.
- Avoid for long listening: blue and violet, which are sharp.
In Shimmr, white, pink, brown, green and orange noise are in the library. You can play one on its own or layer it quietly under a binaural session in the mixer, then let the sleep timer fade everything out.
Common questions
What are the colours of noise?
They are names for how a noise spreads its energy across pitches. The common ones are white (even), pink (softer highs), brown (deep), blue and violet (bright), grey (equal loudness to the ear), plus the informal green and orange.
How many colours of noise are there?
Six have exact technical definitions: white, pink, brown, blue, violet and grey. Green, orange and black are informal names that different sources use in different ways.
Which noise colour is best for sleep?
No colour has been shown to be best for sleep. Many people prefer pink or brown because they sound softer than white, and the right one is the one you notice least at a low volume.
Which noise colour is best for focus or studying?
There is no proven winner. Brown noise is popular for focus because it is easy to tune out, and white or pink cover voices better.
What colour of noise is rain?
Steady rain is closest to pink noise, because it has a broad, soft hiss with less harsh high end than white noise. Heavy rain and distant surf lean towards brown.
From Gareth, who makes Shimmr This article is for general information and is not medical advice. Binaural beats are not a treatment for insomnia or any other condition.