Noise colors, explained
Every colour of noise is the same random hiss with a different tilt. Drag the slider to tilt it and listen: the sound slides from a deep rumble to a thin fizz while the bars show where the energy goes.
The trick is that our hearing works in octaves. From 10 to 20 kHz is one octave, but it holds 10,000 frequencies; from 20 to 40 Hz is also one octave, holding just 20. Spread power evenly across every hertz (white noise) and the top octave ends up with about half of all the energy. That is why white noise sounds so bright.
Tilt it down by 3 dB per octave and each octave gets an equal share: pink noise. Tilt it by 6 dB and the bass dominates: brown noise.
All the noise colours at a glance
| Colour | Slope per octave | Where the energy is | Sounds like |
|---|---|---|---|
| White | 0 dB | Equal per Hz | Bright hiss, TV static |
| Pink | −3 dB | Equal per octave | Steady rain, rustling leaves |
| Brown / red | −6 dB | Mostly bass | Waterfall, aeroplane cabin |
| Blue | +3 dB | Mostly treble | Water spray |
| Violet | +6 dB | Almost all treble | Thin, high hiss |
| Grey | Follows the ear | Equal loudness | Even, slightly bassy |
| Green | Band around 500 Hz | Mid-range | Distant waterfall, wind |
| Black | Near-silent | Faint sub-bass | A quiet room |
The less formal colours
Grey noise is shaped to the ear's equal-loudness curve so every pitch sounds equally loud. Green noise is a popular name for mid-range noise centred near 500 Hz. Black noise usually means silence. None has a single agreed standard, so different apps can sound quite different.
This is one of those ideas that clicks the moment you can hear and see it change together. That's the thinking behind ahaboo, a free site where you steer visual explainers to see how something actually works.
Listen to each colour
- White noise – Flat hiss, equal power per Hz
- Pink noise – Softer, equal power per octave
- Brown noise – Deep rumble, −6 dB per octave
- Green noise – Mid-band, centred near 500 Hz
- Grey noise – Sounds equally loud at every pitch
- Blue noise – Bright, +3 dB per octave
- Violet noise – Very bright, +6 dB per octave
- Black noise – Near-silence, a faint sub-bass hum
Questions
How many colours of noise are there?
The well-defined ones are white, pink, brown (red), blue and violet, each a straight slope on a log-log plot. Grey, green and black are popular labels with looser definitions.
Which noise colour is best for sleep?
Pink and brown are the most common choices because they are soft at high frequencies. White masks more but sounds harsher.
Why are noises named after colours?
By analogy with light. White light contains all visible colours equally; pink light is tilted toward red, the low-frequency end, just as pink noise is tilted toward the bass.