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About this tool
Play white, pink, brown, blue, violet and grey noise plus rain, fan and ocean sounds, mix them and fall asleep with a fading sleep timer.
This white noise generator synthesises every sound in your browser with the Web Audio API — there are no audio files to download. White noise is random samples; pink noise passes them through a −3 dB/octave filter; brown noise integrates them for a deep −6 dB/octave rumble; blue and violet tilt the spectrum upwards; grey is equalised to sound evenly loud. Rain, fan, ocean waves, wind and stream are filtered noise shaped by slow oscillators, so waves really swell and recede. Mix any combination at its own level, watch the live spectrum, save your favourite mixes, and set a sleep timer that fades out gently.
Open White Noise Generator on AltFTool — it loads instantly in your browser.
Press Play, or tap a sound tile such as White, Pink, Brown, Rain, Fan or Ocean waves — each tile switches its layer on or off, and number keys 1–9 do the same.
Drag each layer's volume slider and the Master volume (↑ and ↓ change it by 5%) until the mix sits just loud enough to mask background noise.
Under Sleep timer pick 15 min to 8 h and choose Fade out over 10 seconds to 5 minutes; the remaining time shows next to the Play button and in the tab title.
Type a name and press Save mix to keep the current layers and levels, or load a preset like Deep sleep, Focus or Baby sleep from the Mixes panel.
White, pink, brown (red), blue, violet and grey are generated with their own spectral slopes — the live spectrum shows the difference — and each channel is independent for a wide stereo sound.
Rain, fan, ocean waves, wind and stream can be stacked on top of any noise colour, each with its own volume slider, and toggled with the number keys.
Choose 15 minutes to 8 hours and a fade of 10 seconds to 5 minutes; the volume lowers smoothly to silence instead of cutting off and waking you.
Six preset mixes to start from, and up to 50 of your own mixes kept in this browser's local storage, along with your last levels.
| Colour | Spectrum slope | Sounds like | Often used for |
|---|---|---|---|
| White | Flat (0 dB/octave) | Bright hiss, untuned radio | Masking speech, baby sleep |
| Pink | −3 dB/octave | Steady rain, wind | Sleep, focus, audio testing |
| Brown (red) | −6 dB/octave | Deep rumble, distant surf | Deep sleep, relaxation |
| Blue | +3 dB/octave | Airy, sharp hiss | Masking high-pitched sounds |
| Violet | +6 dB/octave | Very high hiss | High-frequency tinnitus masking |
| Grey | Equal-loudness curve | Even across all pitches | Tinnitus relief, comfort listening |
Slopes describe power per octave relative to white noise. Grey noise in this tool is an approximation made with shelf and peak filters.
White noise is a random signal with equal energy at every frequency across the audible range, which is why it sounds like a bright, steady hiss — similar to an untuned radio. Because it covers all frequencies at once, it masks other sounds such as voices, traffic or a snoring partner by making them less noticeable against the background.
White noise has equal power per hertz, so it sounds bright. Pink noise falls by 3 dB per octave, giving equal energy per octave, and sounds softer, like steady rain. Brown (or red) noise falls by 6 dB per octave and sounds like a deep rumble or distant surf. Many people find pink or brown more comfortable than white for long listening.
Many people sleep better with steady background sound because it reduces the contrast between silence and sudden noises like doors or traffic. Studies are mixed and the effect varies between people. Keep the volume moderate — quieter than normal conversation — and use the sleep timer if you prefer it not to play all night.
At a low volume it is generally considered fine for adults. The concern is loudness: long exposure to sound above about 70 to 85 decibels can harm hearing. Keep the source away from your head, set the volume only as loud as needed to mask disturbances, and consider the fading sleep timer so it stops once you are asleep.
Paediatric guidance suggests keeping sound machines well away from the cot and at a low level — around 50 decibels, about as loud as a quiet shower — because infant ears are more sensitive. Do not place a phone or speaker inside the cot. A timer that fades out after the baby falls asleep reduces total exposure.
Blue noise rises by 3 dB per octave and violet noise by 6 dB per octave, so both are dominated by high, hissy frequencies; violet is sometimes used to mask high-pitched tinnitus. Grey noise is shaped to roughly follow how the ear perceives loudness, so it sounds equally loud from low to high pitch. The grey noise here is an approximation built from filters.
Sound therapy is a common way to make tinnitus less noticeable: a gentle background sound reduces the contrast between the ringing and silence. Some people prefer broadband noise, others a sound pitched near their tinnitus. Try grey, pink or violet noise at a level just below the tinnitus. It is not a cure — speak to an audiologist for persistent tinnitus.
On desktop it keeps playing in a background tab or a minimised window, and the time left on the sleep timer is shown in the tab title. On phones, some browsers suspend web audio when the screen locks or you switch apps, so keep the page open in the foreground if you rely on it overnight.
No. Every sound is generated mathematically on your device, so after the page has loaded no audio is streamed and no data is used while it plays. There are no loops of recorded audio, which also means there is no repeating pattern to notice. Your mixes and levels are stored only in this browser.
Some research suggests moderate background noise can help certain people — including some with ADHD — concentrate, while others find it distracting. Pink or brown noise is often preferred for work because it is less harsh than white. Try a low level for a session or two and see whether it helps you.