White noise basics
The colors of noise explained
Noise has colors, named by analogy with light. Each one spreads sound energy across pitches differently.
The colors of noise describe how a sound's power is spread across pitch. White is flat, pink falls 3 dB per octave, brown falls 6 dB, blue rises 3 dB, violet rises 6 dB, grey is adjusted to equal perceived loudness, green is centered on mid frequencies and black is near silence.
Noise generator: White
Start with a low volume and keep the device away from your baby.
The idea
Light is a mix of colors with different wavelengths. Noise is a mix of pitches with different frequencies. If you boost lows, you get something like "red" light, and noise people name them by loose analogy. The names are conventions, not strict physics.
The main types
| Color | Spectrum | Sounds like | Typical use |
|---|---|---|---|
| White | Flat: equal power per frequency | Bright hiss, static | Masking, sleep, babies |
| Pink | Falls 3 dB per octave | Steady rain, soft hiss | Sleep, focus, babies |
| Brown (red) | Falls 6 dB per octave | Deep rumble, strong wind | Sleep, focus, newborns |
| Blue | Rises 3 dB per octave | Very bright hiss | Audio dithering, rarely for listening |
| Violet | Rises 6 dB per octave | Extremely sharp hiss | Mostly technical |
| Grey | Adjusted to equal perceived loudness | Even across pitches | Hearing tests, some tinnitus therapy |
| Green | Centered on the middle (about 500 Hz) | Natural, wooded | Relaxation |
| Black | Near silence | Almost nothing | Mostly a concept |
White noise
Equal power at all frequencies. Our ears are more sensitive to higher pitches, so it sounds bright. Read what is white noise.
Pink noise
Equal power in each octave, which sounds more balanced to the ear. Close to rain and wind. Read pink noise.
Brown noise
Stronger lows still. Smooth and rumbling. Read brown noise.
Blue and violet noise
The mirror images of pink and brown: more highs, less lows. They sound sharp and are tiring to listen to for long, which is why they are rarely used for sleep. They appear in audio engineering.
Grey noise
Adjusted so that all pitches seem equally loud to the human ear, based on how our hearing varies with frequency. It is used in some hearing and tinnitus applications.
Green noise
A name used for noise centered on the middle of the audible spectrum, around the pitch of nature sounds. It is less standardized than the others.
Which should you use?
For babies, white, pink or brown at a low volume. For adults, whichever sounds comfortable. Try them side by side in the free generator. See also white vs pink vs brown.
Frequently asked questions
How many colors of noise are there?
The common ones are white, pink, brown, blue, violet, grey, green and black. There is no single official list.
Which color of noise is best for sleep?
There is no proven best. White, pink and brown are most used. Personal preference matters.
What color noise is best for babies?
White, pink and brown noise at low volume are most used. Deeper sounds are often popular with newborns.
This page is general information, not medical advice. Talk to your pediatrician about your baby's sleep and hearing, and follow current safe sleep guidance.