White, Pink & Brown Noise Generator

About the White, Pink & Brown Noise Generator

Press Play for steady noise to sleep, focus or mask distracting sounds. Choose white, pink, brown (red), blue, violet or grey noise — or mix several — and shape it with a low-pass and high-pass filter until it sounds like a fan, rain or a waterfall; a slow swell makes it rise and fall like waves. A sleep timer fades the sound out gently and stops it.

The noise is generated on your device from scratch — nothing is downloaded or streamed, so it costs no data and works offline once the page has loaded. You can also save the sound as a WAV file that repeats seamlessly in any music player.

Common uses

• Falling asleep in a noisy home, hotel or hostel.
• Masking office chatter or traffic while you study or work.
• Soothing sound in a nursery, at a safe distance and volume.
• Testing speakers, headphones or room acoustics with pink or white noise.

The colours of noise

Noise colours describe how the sound’s power is spread over pitch:

• White — equal power at every frequency: a bright hiss.
• Pink — power falls by 3 dB per octave (equal power in every octave): softer and fuller, like rain.
• Brown (also called red, after Brownian motion) — power falls by 6 dB per octave: a deep rumble like surf.
• Blue and violet — the reverse: power rises by 3 and 6 dB per octave, giving thin, high hisses.
• Grey — white noise shaped by the inverse of the A-weighting curve used in sound level meters (IEC 61672-1), so that it sounds roughly equally loud at all pitches; the boost of the bass is limited to 20 dB.

Because pink and brown noise have less high-frequency energy, many people find them less harsh than white noise at the same volume.

How the sound is made

For each colour the page builds a 22–24-second stretch of noise (2²⁰ samples at the usual 44.1 or 48 kHz; on devices that run at other sample rates, the power of two that lasts at least 20 seconds) in the frequency domain: every frequency gets a random amplitude and phase with exactly the right average power for that colour, and an inverse fast Fourier transform turns it into sound. The result repeats seamlessly (there is no click or jump at the loop point), the left and right channels play different parts of it, and every colour is limited to 20 Hz–20 kHz and set to the same average level before mixing. The low-pass and high-pass filters are standard 12 dB-per-octave (second-order Butterworth) filters, and a limiter keeps a loud mix from distorting.

Safe listening

This page cannot tell how loud your speakers or headphones are, so judge by ear and start quietly. The World Health Organization’s safe-listening standard for personal audio devices (WHO–ITU, 2019; ITU-T H.870, 2022) uses a reference exposure of 80 dB for 40 hours a week for adults and 75 dB for 40 hours a week for children. WHO also notes that sound levels below 80 dB are unlikely to damage hearing, and that at 90 dB the safe time drops to about four hours a week (WHO: safe listening).

For sleep, noise only needs to be loud enough to blend with the sounds you want to cover. If you cannot hear someone talking at a normal level over it, it is louder than it needs to be. Prefer a speaker across the room to headphones for all-night listening, and use the timer so it does not play all night.

Noise for babies

A study of 14 infant sleep machines (Hugh S.C. et al., Infant sleep machines and hazardous sound pressure levels, Pediatrics 2014;133(4):677–681) measured them at full volume: all of them exceeded 50 dBA at 30 cm, the recommended noise limit for infants in hospital nurseries, and three exceeded 85 dBA, a level that would exceed adult workplace limits if played for more than 8 hours. The practical lessons, which apply to a phone or speaker playing this page too:

• Put the speaker well away from the cot — never in it. In open space, sound drops by about 6 dB each time the distance doubles (a little less in a room).
• Keep the volume low: it should sound soft from where the baby lies.
• Use the sleep timer instead of playing the sound all night.

If you want to know the actual level, measure it at the baby’s position with a sound level meter. Ask your child’s doctor if you have concerns about hearing or sleep.

Sleep timer, background play and phones

The timer’s fade-out is scheduled inside the audio system, so it finishes on time even if the browser slows down a background tab. The sound keeps playing when you switch tabs or minimise the browser on a computer. Phones differ: some keep playing with the screen off, others pause web audio when the screen locks or the browser goes to the background. If yours stops, download a WAV file and play it in your music app set to repeat, together with the phone’s own sleep timer.

Limitations

• The page has no way to measure the volume in decibels; it depends on your device, speakers and system volume.
• Some phones pause browser audio when the screen is locked; the WAV download is the fallback.
• Each colour is a loop of about 22–24 seconds (at least 20 seconds on any device). The loop point is seamless, but very attentive listeners may notice the repetition in some mixes.
• The slow swell is not included in WAV downloads (the rest of the mix is). This is a sound tool, not a medical device, and makes no health claims.

Privacy

Everything happens in your browser. What you enter or open here is not uploaded or stored by MySmartCoPilot.