← Free toolsiOS App Guide
Generated live in your browser · sleep timer

White, pink and brown noise

Three genuinely different noise colours, synthesised on the spot rather than looped from a short clip, with a timer that fades out over the last 30 seconds.

White · pink · brownSleep timer with fade-outNo downloadWorks offline after load

Pick a colour of noise and press play

Sound is synthesised on your device — nothing is streamed.

Status—
Time left—
What you are hearing—

Start at a low volume. Sustained sound above roughly 70 dB through headphones is not safe for overnight use.

How it works

  1. The Web Audio API builds a ten-second noise buffer in memory and loops it, so nothing is streamed or downloaded.
  2. White noise is uniform random samples. Pink noise runs those samples through a Voss–McCartney filter bank so energy falls about 3 dB per octave. Brown noise integrates them, falling about 6 dB per octave — deeper still.
  3. The volume slider is squared before it reaches the gain node, so the middle of the slider sounds like the middle to your ears.
  4. When the timer has 30 seconds left the gain ramps to silence, so you are not woken by an abrupt stop.

What it will never do

  • It makes no health claims. Noise is not a treatment for insomnia, tinnitus or ADHD, and this page will not pretend otherwise.
  • It does not record, listen to, or analyse anything — the microphone is never touched.
  • Nothing is uploaded and nothing is stored; closing the tab ends it completely.

Questions

What is the actual difference between white, pink and brown noise?

It is the slope of the energy across frequency. White is flat and sounds hissy. Pink drops about 3 dB per octave and sounds like steady rain. Brown drops about 6 dB per octave and sounds like a low waterfall. Switch between them on this page and the difference is immediate.

Will it keep playing when my screen locks?

On a phone, a browser tab usually stops or is suspended when the screen locks or you switch apps. That is an OS rule, not a setting on this page — an installed app is the only way around it.

Does it use data while playing?

No. The sound is generated on your device. After the page has loaded you can go offline entirely.

Want noise that keeps playing with the screen off?

Sereno is optional — this free tool runs entirely in your browser and works without it. Check the app’s current App Store listing for exact features, pricing and availability before downloading.

View Sereno on the App Store