Free online brown noise generator
This brown noise generator plays deep, rumbling Brownian noise straight from your browser — no app, no account, and nothing to install. Press play, set the level, and, if you are using it to fall asleep, choose a sleep timer so playback fades out on its own. The sound is synthesised live by the Web Audio API on your own device, so it never buffers, never loops, and uses no data while it runs.
Brown noise is the darkest of the everyday noise colours. Where white noise hisses and pink noise sounds like rain, brown noise sits low and heavy, with most of its energy in the bass. That makes it the colour people tend to reach for when white noise feels too sharp to live with for hours.
What brown noise is
Brown noise is random noise whose power falls by 6 dB for every octave you go up — its power spectrum is proportional to 1/f². Each doubling of frequency carries a quarter of the power of the octave below it, so the low end dominates and the high end is almost absent.
Mathematically, brown noise is what you get when you integrate white noise, or equivalently when you take a random walk: every new sample is the previous sample plus a small random step. That is where the name comes from. It has nothing to do with the colour brown; it honours the botanist Robert Brown, who in 1827 described the jittery random movement of pollen particles in water now known as Brownian motion. Brown noise is also called Brownian noise or red noise — "red" being the colour-based name, by analogy with light that is weighted towards long wavelengths.
What brown noise sounds like
Most people describe brown noise as a deep, steady roar: a waterfall heard from a short distance, heavy surf, strong wind, distant rolling thunder, or the low drone inside an airplane cabin at cruising altitude. There is very little hiss. Compared with white noise it sounds muffled, as if heard through a wall, and many listeners find that softness is exactly what makes it easy to leave on for a long time.
On small phone or laptop speakers brown noise can sound thinner than expected, because those speakers cannot reproduce much of the bass where brown noise keeps its energy. Headphones or a speaker with a proper woofer give a much fuller result.
What people use brown noise for
- Sleep: a steady, low sound floor that covers the small noises of a house at night without the hiss some people find irritating in white noise. Pair it with the sleep timer above if you only want it while you drift off.
- Masking low-frequency noise: brown noise is particularly good at covering rumbly sounds — road traffic, a neighbour's bass or footsteps, an HVAC unit, an engine — because its energy sits in the same range as those sounds.
- Focus and concentration: brown noise has become popular online, especially among people with ADHD, many of whom say it helps them settle into work. Those reports are anecdotal: there is some research suggesting background noise helps certain people concentrate, but no solid evidence that brown noise in particular treats ADHD. It is simply worth trying.
- Relaxation and tinnitus comfort: some people with tinnitus find a gentle, low-pitched background sound more comfortable than a bright one. Tinnitus that is high-pitched may be masked better by white or grey noise, so it is worth comparing.
- Sound design: brown noise is a useful raw material for wind, rumble, ocean and engine effects, usually shaped further with filters.
Brown noise vs pink noise vs white noise
All noise colours are random; they differ only in how the energy is tilted across the spectrum. Every one of them is available in the Harmonoise noise generator.
| Colour | Spectral slope | Character | Typically used for |
|---|---|---|---|
| White | Flat (0 dB/octave) | Bright, hissy, like radio static | Masking, broadband testing, dithering |
| Pink | −3 dB/octave | Balanced, like steady rain | Room and speaker calibration, long listening |
| Brown | −6 dB/octave | Deep, like a waterfall or distant thunder | Sleep, masking low rumble, focus |
| Grey | Equal-loudness weighted | Perceptually even | Hearing tests, tinnitus therapy |
A practical rule of thumb: if white noise feels harsh, try pink; if pink still feels too bright, try brown. If brown feels muffled or boomy, pink or grey sit in between. The full breakdown, including blue and violet noise, is in the guide to the colors of noise.
What is "deep brown noise"?
"Deep brown noise" is not a technical standard — it is the name playlists and apps give to brown noise with even less treble, usually made by adding an extra low-pass filter so that only the rumble remains. It sounds closer to the inside of an airplane or a distant storm than to a waterfall. You can get most of the way there with this generator by playing it through headphones or a speaker with good bass and keeping the volume low, which makes the ear even less sensitive to the remaining high frequencies. For a darker file to keep, export a WAV and apply a low-pass filter (around 200–500 Hz) in any audio editor.
How to download brown noise as a WAV file
- Open the noise generator with brown selected.
- Set the duration you need, down to the millisecond — a short clip for sound design or an hour for an overnight loop.
- Choose a sample rate (44.1 kHz for general use, 48 kHz for video, 96 kHz for measurement work) and a bit depth.
- Pick mono or stereo. Stereo generates two independent noise streams, which sounds wider and more enveloping over headphones.
- Click Export WAV File. The file is rendered locally and downloaded straight to your device.
The result is an uncompressed WAV that imports cleanly into any DAW, video editor or media player, and you can load it onto a phone or white-noise machine for offline use.
Choosing a safe listening volume
Brown noise is deceptively easy to play too loud. Because it has so little high-frequency content, it feels gentle even at levels that carry a lot of acoustic energy, and on headphones that energy goes straight to your ears. Start quiet, raise the level only until it just covers what you want to mask, and for all-night listening keep it at a level you could comfortably talk over. Speakers across the room are a safer choice for sleep than headphones, and for infants keep the source well away from the cot and the level low.
How this generator makes brown noise
Each channel starts from independent white noise — uniform random samples between −1
and +1 — which is fed through a leaky integrator:
brown = (brown + 0.02 × white) / 1.02, with the result multiplied by 3.5 to
bring it up to a usable level. A pure integrator would wander off without limit, so the small
"leak" (the division by 1.02) gently pulls the signal back towards zero. In practice that
gives the characteristic −6 dB-per-octave slope above roughly 140–150 Hz and a
flat shelf below it, which keeps the output free of DC drift and clipping. Everything runs locally
through the Web Audio API — no audio is recorded, uploaded, or sent anywhere.
Frequently asked questions
Why is it called brown noise if it has nothing to do with the colour?
The name comes from Brownian motion, described by the botanist Robert Brown in 1827. A brown noise signal behaves like a Brownian random walk: each sample is the previous one plus a small random step. It is also called Brownian or red noise; red is the colour-based name, by analogy with light whose energy is weighted towards the long wavelengths.
Is brown noise better than white noise for sleep?
Many people prefer it, because it has far less high-frequency hiss and masks low sounds such as traffic rumble well. There is no strong evidence that one colour is universally better for sleep, though; the best choice is the one you find comfortable at a moderate volume. Try each for a few nights and keep the one you stop noticing.
Does brown noise help with ADHD or focus?
Brown noise became popular online among people with ADHD who report that it helps them focus. Those reports are anecdotal. Some research suggests background noise can help certain listeners concentrate, but there is no solid evidence that brown noise specifically treats ADHD. It is a low-risk thing to try at a moderate volume, and not a substitute for professional advice.
Can I download brown noise as a file?
Yes. The full noise generator exports brown noise as an uncompressed WAV at 22.05, 44.1, 48 or 96 kHz, in 16-bit, 24-bit or 32-bit float, mono or stereo, with the duration set to the millisecond. Everything is rendered in your browser and nothing is uploaded.