White, pink or brown noise: what is the difference?
All three are steady, random sounds. What changes is how their energy is spread between low and high pitches, which is why white noise hisses, pink noise sounds like rain and brown noise rumbles.
Short answer: white noise has equal energy at every frequency and sounds bright, like a hiss or TV static. Pink noise loses energy as pitch rises (about 3 dB per octave) and sounds softer, like steady rain. Brown noise drops off twice as fast (about 6 dB per octave) and sounds deep, like a low rumble or distant waterfall.
The three at a glance
| White noise | Pink noise | Brown noise | |
|---|---|---|---|
| Sounds like | Hiss, static, a fan up close | Steady rain, rustling leaves | Low rumble, waterfall, strong wind |
| Energy | Equal at every frequency | Falls about 3 dB per octave (1/f) | Falls about 6 dB per octave (1/f²) |
| Feels | Bright, crisp | Balanced, soft | Deep, warm |
| Often used for | Babies, masking voices | Sleep, reading, studying | Adult sleep, snoring, traffic, long focus |
White noise
White noise is defined as a random signal with a flat spectrum: every frequency band of the same width carries the same power. Because our ears hear many more high-frequency bands than low ones, it sounds bright and hissy. It is very good at covering speech and sudden household sounds, which is why it is the classic choice for baby sleep machines. In HushNest, White Noise plays over a painted garden scene and is free on every device.
Pink noise
Pink noise has equal power in every octave, so its power per frequency falls as 1/f, about 3 dB per octave. To most ears it sounds more even and natural than white noise, closer to rain or wind in the trees. In sleep labs, researchers have used short bursts of pink noise timed to brain waves to boost deep sleep, but that is a precise lab technique, not the same as listening to a continuous track.
Brown noise
Brown, or Brownian, noise falls off as 1/f², about 6 dB per octave, so most of its energy sits in the bass. It sounds like a distant waterfall or the inside of an aeroplane. Many adults find it the most comfortable to listen to for hours, and its low end covers snoring, traffic and building hum well.
Which should you choose?
- For a baby: start with white noise, womb or heartbeat. See white noise for babies.
- For your own sleep: try brown noise or pink noise first, then rain or fan. See white noise for adult sleep.
- For a snoring partner or traffic: brown noise, fan or air conditioner.
- For focus: brown noise for long sessions, pink noise or rain for reading. See white noise for focus.
- For tinnitus at bedtime: some people find a soft background sound makes tinnitus less noticeable; the NHS and the American Tinnitus Association describe this as sound therapy. Ask a doctor or audiologist for advice.
Not sure? HushNest lets you layer up to four sounds, so you can put soft rain over brown noise and adjust each volume until it sounds right, then save the mix.
Sources
- Colors of noise, Wikipedia: definitions of white (flat), pink (1/f) and Brownian (1/f²) spectra.
- Ngo HV, Martinetz T, Born J, Mölle M. Auditory closed-loop stimulation of the sleep slow oscillation enhances memory. Neuron. 2013;78(3):545-553. doi:10.1016/j.neuron.2013.03.006
- Riedy SM, Smith MG, Rocha S, Basner M. Noise as a sleep aid: a systematic review. Sleep Med Rev. 2021;55:101385. doi:10.1016/j.smrv.2020.101385
- NHS. Tinnitus: treatment. American Tinnitus Association. Sound therapy.
Questions people ask
Which noise colour is best for sleep?
There is no proven winner. Many adults prefer brown or pink noise at night because they sound softer and deeper; white noise is a classic choice for babies and for masking voices. Choose the one you find most comfortable.
Is brown noise the same as red noise?
Usually, yes. Brown noise is named after Brownian motion, not the colour, and is also called red noise. Its energy falls by about 6 dB for every octave you go up in pitch.
Why is pink noise called pink?
By analogy with light: white light has all colours equally, and light weighted toward lower frequencies looks pink or red. Pink noise likewise has more energy in the lower frequencies than white noise.
What does green noise mean?
Green noise is an informal name for sound concentrated in the middle frequencies, often described as sounding like nature. It is not a standard technical term. Rain, stream and forest sounds give a similar feel.
Does HushNest have all three?
Yes. White noise is free on Android and iPhone. Pink and brown noise are free on Android and part of HushNest Plus on iPhone.
Try HushNest tonight
Free on Android and iPhone, with no account needed. On the App Store it is listed as HushBaby: Baby Sleep Sounds.
