What Is Brown Noise?

Brown noise is deep, soft noise with most of its energy in the low frequencies. It’s named after a scientist, not a color. Press play to hear it as you read.

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The short answer

Brown noise1 is random sound whose power falls by 6 decibels for every octave you go up. In practice that means a lot of bass and very little treble: a deep, smooth roar like a distant waterfall, heavy surf heard indoors, or the inside of an airplane. It’s also called red noise or Brownian noise.

Named after Robert Brown

In 1827 the botanist Robert Brown watched tiny particles released from pollen grains jiggle about at random in water. That motion, explained by Einstein in 1905 as molecules bumping into the particles, is called Brownian motion2. If a signal wanders the same way, each step a small random nudge from the last, it has exactly the spectrum of brown noise. That’s how MoodNoise makes it: a random walk, gently pulled back toward the middle so it never drifts away.

NoisePower per hertzPower per octaveSounds like
WhiteFlat+3 dB each octave upTV static, air from a vent
Pink−3 dB per octave (1/f)Equal in every octaveSteady rain, wind in trees
Brown−6 dB per octave (1/f²)−3 dB each octave upDistant waterfall, heavy surf
Blue+3 dB per octave+6 dB each octave upA fine, high hiss
Violet+6 dB per octave+9 dB each octave upA sharp, airy hiss

Why it became so popular

Brown noise went viral a few years ago, with millions of people, many with ADHD, describing it as calming their thoughts. The science specific to brown noise is thin: a 2024 meta-analysis of noise and attention found 13 studies of white and pink noise and none of brown 3, and sleep research has used white or pink noise too. What we can say with confidence:

  • It’s comfortable. With little high-frequency energy, it doesn’t tire your ears.
  • It masks low sounds well: traffic, rumbling appliances, bass from a neighbor.
  • It’s weaker at masking voices than white or pink noise, because speech sits higher. Add a little pink if voices get through.

Using brown noise

For sleep, see brown noise for sleep. For work, see brown noise for studying. The brown noise generator lets you mix it with rain, a fan, the ocean and more.

One tip: small phone speakers can’t play deep bass, so brown noise can sound faint or tinny on them. Earbuds or a speaker make a big difference.

Hear the difference

Sources

  1. Wikipedia. Brownian noise. en.wikipedia.org.
  2. Wikipedia. Brownian motion. en.wikipedia.org.
  3. Nigg JT, Bruton A, Kozlowski MB, Johnstone JM, Karalunas SL (2024). Systematic review and meta-analysis: Do white noise or pink noise help with task performance in youth with ADHD or with elevated attention problems?. Journal of the American Academy of Child and Adolescent Psychiatry 63(8):778–788.

Questions

Why is it called brown noise?

After Robert Brown, who described Brownian motion. A signal that moves like a particle in Brownian motion has the brown noise spectrum. It has nothing to do with the color.

Is brown noise the same as red noise?

Yes. Red noise and Brownian noise are other names for it.

Is brown noise good for ADHD?

Many people with ADHD find it helpful. Research specific to brown noise is limited; some studies with white noise found benefits for people who are easily distracted.

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