How to use the brown noise generator
- Press Play (or the Space bar). The rumble fades in over about a second.
- Set the Volume. Brown noise can feel quieter than it is because most of its energy is in the bass, so raise it slowly.
- Choose a Sleep timer, or leave it off to play until you stop it. With a timer, the sound fades out over the last 45 seconds.
- Use Softness to make it even deeper. Brown noise is already dark, so the effect is subtle until the slider is well to the right.
- Turn on Gentle variation for a slow, wave-like drift in tone and level.
Your settings are remembered in this browser. On a phone, leave the tab open and lock the screen: on most phones the sound keeps playing. Small phone speakers reproduce very little deep bass, so brown noise sounds fuller through headphones or a larger speaker.
What is brown noise?
Brown noise, also called Brownian noise or red noise, is random noise whose power spectral density is proportional to 1/f². Its power falls by about 6 dB per octave, twice as steeply as pink noise, so the bass dominates and there is very little hiss. The name has nothing to do with the colour: it comes from Brownian motion, the random jiggling of particles described by the botanist Robert Brown. Add up white noise step by step, a random walk, and the result is brown noise.
The result is a deep, smooth rumble: a strong waterfall heard from a distance, heavy surf, the steady roar inside an aircraft cabin or far-off thunder. Many people find it the most soothing noise colour because it lacks the bright "shhh" of white and pink noise.
This generator builds brown noise the same way, by integrating random samples, with a slight leak below about 25 Hz so the signal cannot wander off into inaudible sub-bass. Above that, it follows the −6 dB per octave slope across the audible range. Two long buffers with different loop lengths play together and the left and right channels are independent, so the rumble never repeats audibly and feels wide on headphones.
Brown noise vs pink and white noise
| Colour | Power spectral density | Slope | Sounds like |
|---|---|---|---|
| White | Flat | 0 dB/octave | Static, bright hiss |
| Pink | 1/f | −3 dB/octave | Steady rain, wind |
| Brown (red) | 1/f² | −6 dB/octave | Waterfall, distant thunder, cabin roar |
Because it is so bass-heavy, brown noise covers low, rumbling sounds such as traffic, a washing machine or a neighbour's music well, and sharp, high sounds such as voices less well. If you need to mask speech, white or pink noise may work better; for something in between, try green noise or a fan sound. The guide white, pink and brown noise: what's the difference? compares them in more detail.
When people use brown noise
- Sleep: its low, steady roar is a popular alternative to white noise for people who find hiss irritating.
- Focus: brown noise became popular online as a "focus sound", including among people with ADHD. Many say it helps quiet their surroundings or their thoughts, but this is mostly personal experience.
- Blocking low-frequency noise: traffic rumble, plumbing, air-conditioning units or bass from next door.
- Travel and relaxation: the cabin-like roar can be calming on its own or layered with rain in the sleep sounds mixer.
What does the research say?
There is very little research on brown noise specifically. Most studies of noise and sleep used white or pink noise, and their results are mixed: steady sound can mask disturbing noises and help some people fall asleep, while reviews have rated the evidence as low quality overall. Studies of background noise and attention, including in children with attention difficulties, suggest it helps some people and hinders others.
So the honest summary is: brown noise is a pleasant, low-risk way to mask the sounds around you, and if it helps you relax or concentrate, that is a good enough reason to use it. It is not a treatment for insomnia, ADHD, anxiety or tinnitus, and persistent problems deserve a conversation with a doctor.
Listening safely
Bass is felt as much as heard, so it is easy to turn brown noise up louder than you realise. Keep it at a moderate level, quieter than normal conversation for sleep, and be especially careful with earphones and long listening; take breaks and keep the level low overnight. The volume control is capped, but your device volume adds to it. For a quick check of your ears, use the online hearing test.
Privacy: the brown noise is generated in your browser on your device. Nothing is downloaded or uploaded, and only your settings are stored, locally in this browser. Find rain, ocean waves, lullabies and more on the sleep and relaxation sounds page, or time a focus block with the online timer.
Frequently asked questions
What is the difference between brown noise and white noise?
White noise has equal power at every frequency and sounds like a bright hiss. Brown noise loses about 6 dB of power per octave, so it is dominated by low frequencies and sounds like a deep rumble.
Is brown noise the same as red noise?
Yes. Brown, Brownian and red noise all describe noise with a 1/f² spectrum. "Brown" refers to Brownian motion, not the colour.
Does brown noise help with ADHD or focus?
Many people say it helps them concentrate, but there is little research on brown noise specifically, and studies of background noise and attention show mixed results. It is worth trying, but it is not a treatment for ADHD.
Why does brown noise sound quiet on my phone?
Phone speakers reproduce very little deep bass, which is where most of brown noise's energy is. Headphones or a larger speaker give a much fuller sound. Do not compensate by turning the volume up very high.
Can I fall asleep with brown noise playing all night?
At a low volume this is generally considered fine for adults. Use the sleep timer if you only need it while falling asleep, and avoid loud overnight listening through earphones.
Does brown noise ever loop or repeat?
Not audibly. Two long random buffers of different lengths play together, so the combined pattern only repeats after about 95 minutes, and the joins are cross-faded.
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