Brown Noise Generator
The generator below is set to brown noise, the deepest of the three colors it offers. Press play and you get a continuous low rumble with very little hiss in it, closer to distant surf or a waterfall than to radio static. There is a volume slider and a sleep timer that fades out rather than cutting off.
Everything runs in your browser. No audio is ever uploaded.
Settings
Audio starts on your first tap on Play, as required by your browser. Press Space to start or stop.
Brown, pink and white compared
| Color | Spectrum | How it sounds | Usually chosen for |
|---|---|---|---|
| Brown | Falls 6 dB per octave | Deep rumble, almost no hiss | Sleep, tinnitus, masking traffic |
| Pink | Falls 3 dB per octave | Balanced, like steady rain | Focus, general masking, speaker checks |
| White | Flat across the spectrum | Bright and hissy, like static | Masking speech, testing equipment |
What makes noise brown
Brown noise is not named after the color. It comes from Robert Brown and the random walk known as Brownian motion: each sample is the previous sample plus a small random step, rather than an independent random value. Integrating a random signal that way tilts its spectrum, and the result is a power density that falls by 6 dB for every octave you go up, twice as steep as pink noise.
The consequence is that almost all of the energy sits at the bottom. Between 20 and 40 Hz there is as much power as in the entire range above 1 kHz, which is why the sound reads as a rumble with the top end filed off. It is sometimes called red noise, by analogy with the low frequency end of the visible spectrum, and the two names mean the same thing.
Why it reads as a rumble
Human hearing is least sensitive at the extremes and most sensitive around 2 to 5 kHz, the range that carries the consonants of speech. White noise puts equal power at every frequency, and because there are far more octaves above 1 kHz than below it, white noise lands squarely in that sensitive region and sounds bright and fatiguing. Brown noise starves the same region, so what is left is felt more than heard.
That is also why brown noise seems louder on good hardware than on a laptop. Small speakers roll off sharply below about 150 Hz, and on a phone the effect is stronger still, so most of what makes brown noise brown never gets reproduced and it can end up sounding like quiet pink noise. Headphones, or a speaker with real low end, change the experience completely.
Sleep, focus and tinnitus
For sleep, brown noise works by masking: a steady background raises the noise floor so that a door closing or a car passing no longer stands out against silence. Low frequency energy suits that job because traffic and building noise are themselves low, and it adds none of the hiss that keeps some people awake. Set the sleep timer so it fades out after you are likely to be asleep.
For focus and tinnitus the picture is less settled. Some people concentrate better with a steady low background and others are distracted by any sound at all, and there is no strong evidence favouring one color over another. Tinnitus masking is a recognised technique and brown noise is a common choice, but the useful pitch depends on what you hear, so the tinnitus frequency matcher is a better starting point than a guess.
Setting the level, and when to stop
Broadband noise is easy to run too loud because it has no peaks to warn you. Set it just loud enough to blur the sounds you are masking and no louder: if it covers them completely, it is louder than it needs to be. All night exposure at a high level is the pattern worth avoiding, particularly with headphones on a child's device, where a fixed volume limit is a sensible precaution.
Two practical limits. Browser audio has no calibration, so the slider here is relative to your system output and gives you no dB figure; use the decibel meter with a phone if you want a rough number. And the sound is generated live in this tab, so it ends when you close it. Leaving the tab open with the sleep timer set is the reliable way to run it overnight.