A free noise generator for sleep, focus and masking
The Noise Generator plays six colours of noise — white, pink, brown, blue, violet and grey — straight from your browser, for as long as you like. Mix colours together to taste, set the volume, and use the sleep timer to fade the sound out gently after anything from 10 minutes to 8 hours. You can also download a seamless-looping WAV to use in any music app.
Steady broadband noise is one of the oldest tricks for falling asleep in a noisy flat, concentrating in an open-plan office, calming a baby, or taking the edge off tinnitus. It works by masking: a constant, featureless sound raises the background level so that sudden noises — a door, traffic, a neighbour’s TV — stand out less and are less likely to pull your attention or wake you.
The noise is synthesised locally with the Web Audio API — nothing is streamed, so it keeps playing without using data or buffering.
How to use the Noise Generator
- Tick one or more noise colours. Brown noise is a good starting point for sleep; pink for focus.
- Set each colour’s level with its slider to shape the mix, and the master volume to a comfortable, low level.
- Choose a Sleep timer if you want the noise to stop by itself, and how long the fade-out should take.
- Press Play. The spectrum display shows what is playing; the countdown shows when it will stop.
- To use the sound elsewhere, set a length and press Download WAV; the file is made to loop without a click.
Noise Generator features
Six noise colours
White, pink (Paul Kellet’s filter), brown, blue, violet and a grey approximation shaped toward the ear’s equal-loudness curve.
Layer mixer
Combine colours at independent levels — a little white over brown adds “air” without the harshness of pure white noise.
Sleep timer with gentle fade
Stop after 10 minutes to 8 hours, with a fade-out of 30 seconds to 5 minutes so the silence does not wake you.
Seamless loops
Each colour is a 10-second buffer with a crossfaded join, looped sample-accurately, so there are no clicks or repeating patterns.
Live spectrum
A log-frequency bar display shows the balance of bass and treble in the current mix.
WAV download
Export 5 seconds to 10 minutes of your mix as a 16-bit, 44.1 kHz mono WAV that loops cleanly.
What the colours of noise mean
Noise “colours” describe how energy is spread across frequencies, by analogy with light. The slopes below are measured per octave (each doubling of frequency).
| Colour | Spectral slope | Sounds like | Often used for |
|---|---|---|---|
| White | 0 dB/octave (flat) | Hissing static, TV snow | Masking high-pitched sounds, baby sleep machines |
| Pink | −3 dB/octave | Steady rain, wind in trees | Focus, studying, speaker testing |
| Brown (red) | −6 dB/octave | Surf, waterfall, aircraft cabin | Sleep, relaxation, masking traffic rumble |
| Blue | +3 dB/octave | Fine spray, hiss | Dithering in audio engineering |
| Violet | +6 dB/octave | Very sharp hiss | Tinnitus pitch-matching |
| Grey | Equal-loudness shaped | Balanced, “neutral” noise | Masking that sounds even across pitches |
Choosing a noise for sleep, work or tinnitus
- Sleep: most people prefer brown or pink. Set the volume just loud enough to blur the sounds that disturb you — typically about as loud as a quiet conversation in the next room — and use the timer with a long fade.
- Focus: pink noise or a pink-and-brown mix masks office chatter without being fatiguing. Speech is the hardest sound to ignore, and steady noise around 300–3,000 Hz is what covers it.
- Babies: keep the sound source well away from the cot and the level low — paediatric guidance generally suggests staying under about 50 dB at the child’s ear and not running it all night at high volume.
- Tinnitus: many people find that low-level broadband noise makes their tinnitus less noticeable, particularly at bedtime. Try pink or white first, or violet if your tinnitus is very high-pitched. This is comfort, not treatment — see an audiologist about persistent tinnitus.
- Pair it with the Pomodoro Timer for work sessions, or the Sleep Calculator to plan a bedtime around sleep cycles.
How the noise is generated
White noise is simply a stream of random samples. Pink noise is made by passing white noise through the seven-pole filter published by Paul Kellet, which approximates the −3 dB per octave slope to within about ±0.05 dB across the audible band. Brown noise is a leaky integration (a running sum that slowly decays) of white noise, giving −6 dB per octave — the same spectrum as Brownian motion, hence the name. Blue and violet noise are the first differences of pink and white noise respectively, which tilts their spectra upward. Grey noise blends the others to approximate the inverse of the ear’s equal-loudness curve. Every buffer is normalised to the same peak level and crossfaded at the loop point. For a single pure frequency rather than noise, use the Tone Generator.
Noise Generator FAQ
Is the noise generator free and does it play offline?
It is free with no account. The sound is generated on your device, so once the page has loaded it needs no further data; it keeps playing as long as the tab stays open.
Will it keep playing when my phone screen turns off?
In most mobile browsers, yes — audio started by a tap keeps playing with the screen off, like a music app, and the sleep timer continues. Some battery-saver modes do pause background tabs; if that happens, keep the screen on at low brightness or download the WAV and play it in your music app.
What is the difference between white noise and brown noise?
White noise has equal energy at every frequency and sounds like bright hiss. Brown noise rolls off by 6 dB every octave, so it is dominated by low rumble, like surf or a plane cabin. Most adults find brown noise more comfortable for sleep.
Is white noise safe to sleep with every night?
At moderate volume, there is no evidence of harm for adults, and a steady sound can make waking from sudden noises less likely. Keep the level comfortably low, and for babies keep the device at a distance and the volume down.
Can noise help with tinnitus?
Many people find that low-level noise makes tinnitus less intrusive, especially when trying to sleep; it is a common component of sound therapy. It does not cure tinnitus, so consult an audiologist or doctor about ongoing symptoms.
Why does the downloaded file sound slightly different from the live player?
The live player mixes freshly generated noise in real time; the WAV is a mono render normalised to a safe peak level. The spectral balance is the same, so any difference is in loudness rather than tone.