Brown Noise: Free Online Generator

Brown noise is the deepest of the three classic noise colors: a rolling, bass-heavy sound that masks low-frequency disturbances and feels closer to ocean surf or a distant freight train than to static. NoiseMoon generates it procedurally in your browser. No file loop. No upsell. Works offline once installed.

What is brown noise?

Brown noise is a random signal whose power spectrum decreases by 6 decibels per octave as frequency rises. The name comes from Brownian motion (the same random-walk process the noise resembles), not from the color brown. Compared to the more familiar white noise (flat across all frequencies) and pink noise (−3 dB/oct), brown noise puts most of its energy at the bottom end. It sounds darker, smoother, and more like a sustained low rumble than a hiss. Headphone listeners often describe it as “filling the room from underneath.”

What brown noise does

Brown noise tends to mask low-frequency environmental sounds: HVAC rumble, distant traffic, partner snoring, footsteps from the floor above. It’s especially effective when the disturbance you’re trying to ignore lives in the bottom two octaves of human hearing, which is exactly where most household and street noise concentrates. Brown noise is not a treatment. Some people prefer its low-frequency balance for focus; others do not. The same goes for sleep: some listeners find the smoother spectrum more comfortable than the brighter hiss of white noise, and some don’t. Choose whatever feels right to your ears.

How to use it

Start at a low, comfortable volume. Use the Tone slider (Warm to Bright) to taste; full Warm gives you the deepest, most rumble-like tone. If you like the extra-dark sound of many popular brown noise videos (in our survey, 21 of them had a mean slope of −12.05 dB/oct, darker than textbook brown), try the Spaceship sound: brown noise with the highs rolled off, darker than plain Brown. If you want pure mathematical brown noise, use Brown (selected by default on this page) and set the Tone slider to Balanced. Headphones or a speaker both work; pick whichever is more comfortable for the session.

Try it in NoiseMoon

Brown noise is not a treatment. Some people prefer its low-frequency balance for focus; others do not. Response is individual. In NoiseMoon you can hear the difference for yourself: the Spaceship sound gives you a darker shape with the highs rolled off, other sounds sit closer to textbook brown, the Tone slider tilts the spectrum in real time, and the timer fades the sound out on your schedule. NoiseMoon is not medical advice; consult a clinician for clinical questions.