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.
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free · offline · never repeats
Audio is analyzed on-device only and discarded immediately. Nothing is recorded, stored, or transmitted.
If silent, check iPhone mute switch (side toggle).
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." [citation needed: source for the −6 dB/octave definition; e.g. a standard DSP textbook reference]
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. Anecdotally, many listeners with ADHD report that brown noise reduces auditory restlessness and helps them settle into focused work; recent research has begun to formalize this effect. For sleep, brown noise's smoother spectrum is often preferred over the harsher hiss of white noise, particularly for side-sleepers and people with mild tinnitus. [citation needed: sleep-masking and ADHD effect references — see e.g. JAACAP 2024 meta-analysis]
How to use it
Start at low volume — around 50 dB SPL is the commonly recommended ceiling for overnight use. Use the warm ↔ bright slider to taste; full warm gives you the deepest, most rumble-like tone. The Spaceship preset (selected by default on this page) is calibrated to match the spectral shape of the most popular brown noise tracks online — about −12 dB/octave, which is darker than textbook brown but is what most modern listeners actually mean when they search for "brown noise." If you want pure mathematical brown noise, switch to the Cabin or another preset and dial the warm slider toward bright. Headphones are optional but improve isolation; for sleep, an external speaker placed several feet from your head is gentler.
Research and evidence
Peer-reviewed work on brown noise specifically is sparse compared to white noise, but the broader literature on broadband acoustic masking and "stochastic resonance" provides relevant evidence. Sleep studies have repeatedly found that continuous low-frequency masking sounds reduce wakefulness during the night, particularly in noisy environments [citation needed]. For ADHD, a 2024 meta-analysis published in the Journal of the American Academy of Child & Adolescent Psychiatry reviewed acoustic-noise interventions and found small-to-moderate effects on attention and task performance, with brown and pink noise showing the strongest signal among the colors tested [citation needed]. For tinnitus, audiology guidance generally favors broadband notched or matched-spectrum stimuli; brown noise is sometimes used as a starting point. None of this is medical advice — consult a clinician for clinical questions.
Frequently asked
Is brown noise safe to listen to all night?
At moderate volume (below ~60 dB SPL), brown noise is considered safe for overnight listening. NoiseMoon's procedural generation has no loop seam, so the brain isn't pattern-matching repeated audio — a quiet but real advantage over file-based loops. [citation needed]
What's the difference between brown noise and pink noise?
Brown noise rolls off at −6 dB per octave (twice as steep as pink), making it noticeably darker and bass-heavy. Pink noise rolls off at −3 dB/oct and sounds more like steady rainfall. Brown is closer to low rumble or distant traffic; pink is closer to a fountain.
Does brown noise really help with ADHD?
Some research suggests broadband noise (including brown) may improve attention in people with ADHD via a phenomenon called stochastic resonance. Effects are individual; some people find it useful, others don't. [citation needed]
Can I use brown noise for a baby's sleep?
Pediatric guidance generally favors lower-volume continuous sound for infants. If you use it, keep volume low, place the device several feet away from the crib, and consult your pediatrician for newborns.
Why does NoiseMoon's brown noise sound different from YouTube videos?
Most popular YouTube "brown noise" tracks are looped audio with extra low-pass filtering applied — closer to −12 dB/oct than textbook −6. NoiseMoon offers both: the Spaceship preset matches that popular dark-brown sound, while you can dial down to pure mathematical brown via the warm/bright slider.
Does NoiseMoon work offline?
Yes. Add NoiseMoon to your home screen (PWA install) and the entire app runs offline — no streaming, no buffering. The noise is generated mathematically on your device, sample by sample.