Free online brown noise generator

What is brown noise?

Brown noise is a random sound signal whose energy falls away steeply as pitch rises: roughly 6 decibels per octave, twice the slope of pink noise and far steeper than white noise, which holds equal energy at every frequency. Nearly all of its power therefore sits at the bottom of the spectrum, which is why the ear reads it as a deep, enveloping rumble instead of a hiss.

The name has nothing to do with the color. It comes from Brownian motion, the random walk that describes a particle jostled by its neighbors, and which is literally the process used to generate the signal. It is also called Brownian noise or red noise, red being the low-frequency end of the visible spectrum by analogy.

What brown noise may help mask

The mechanism is masking, and it is better established than any claim about one color beating another. A quiet room is not a calm room: it is a room with a low noise floor, where every door, car and shifting partner arrives as a sharp contrast against near silence. Those contrasts are what pull you out of sleep, not the absolute loudness.

Steady broadband sound raises the floor so those events no longer stand out against it. Brown noise does that job while keeping its energy low in the spectrum. Some listeners find that balance less sharp than white noise, but there is no strong evidence that brown is the best color for sleep.

Be skeptical of stronger claims. Brown noise went viral on the back of anecdotes about ADHD and racing thoughts, but it is not an established ADHD treatment and research on this color is thin. We went through what the evidence actually supports, including where it runs out.

How loud should you set it?

Most people set it too high and never find out. The target is the minimum volume that still masks, not a volume that drowns the room.

1. Start from silence, with the real noise present. Set it up at night, in your actual room, with whatever is bothering you actually happening. A sample judged in a quiet afternoon tells you very little.
2. Raise it until the disturbance stops registering. Not until it disappears from the room, which is a different and much louder thing. You want the point where your attention stops being pulled toward it.
3. Then come back down. Ease it lower until masking just starts to fail, and settle a little above that. This is usually well below where step two left you.

A rough test: if you would have to raise your voice to talk over it, it is louder than the job requires. Sitting at the minimum that works is easier on your ears across a night, and it is the reason the volume control here is a continuous slider rather than ten coarse steps.

How this generator actually works

Most sites that offer brown noise are playing you an audio file on a loop. This one is not. Every sample you hear is computed in your browser, in real time, by a port of the same generator that runs inside the Veil app.

The signal is a leaky-integrator random walk with a corner near 65 Hz, which produces the 1/f² spectrum that defines brown noise: minus 6 decibels per octave. A live low-pass filter at 4 kHz then runs continuously over the output, so its state never resets.

Brown noise depends on the speaker. Phone and laptop speakers may not reproduce its deepest frequencies, so a thin result can be a hardware limit rather than a problem with the generator.

Two independent walks are mixed together. The first buffer is 30 seconds. The second starts at 37 seconds and is extended by the smallest offset needed to make the sample counts coprime, which is one sample at common rates such as 44.1 kHz. Whole-second 30- and 37-second buffers would line up again after 18.5 minutes; the extra sample moves the combined cycle to about 1.55 years at 44.1 kHz. Each loop boundary is crossfaded against continuation samples rather than fading to silence, which is designed to soften the individual boundaries and avoid a short repeated pattern.

It runs entirely on your device. No account, no signup, no ad, and nothing sent anywhere.

Brown, white or pink: which should you use?

There is no single answer, and anyone who gives you one is guessing on your behalf. The differences are real but the right choice is personal, so the only reliable method is to hear them next to each other at your real sleeping volume.

• Brown for a busy mind, or when white noise feels sharp.
• White when the room is genuinely loud and you need maximum coverage, since it puts energy where voices and traffic sit.
• Pink as the researched all-rounder and the usual starting point, sitting between the two.

Hear all six colors side by side, including green, grey and blue, or read the longer comparison of white noise vs pink noise vs brown noise. If noise is not the right texture, there are also seven fan sounds.