White, pink and brown noise generator with WAV export

How to use the noise generator

1. Turn your device volume down first.
2. Under Noise, choose White, Pink or Brown. Pink is selected at first.
3. Press Play. Move the Volume slider (1–100%, default 30%) to a comfortable level; it changes smoothly while the sound plays. Press Stop to end.
4. To keep a copy, set Export length in seconds (1 to 3,600) and press Export WAV. A player and a download button appear under the controls.

What it does and when to use it

Steady noise covers up sounds that come and go, such as talking in the next room or traffic, which is why people play it for focus or sleep. It is also a test signal. Pink noise is the usual choice for checking whether a speaker or a pair of headphones sounds even from bass to treble, because each octave carries the same energy.

Use the tone generator when you need a single pitch instead of a spread of frequencies, and the audio playback tester to check that left and right channels are wired correctly. To watch the spectrum of the noise while it plays through a microphone, try the audio spectrum analyzer.

How it works

Everything is calculated in your browser. White noise is a stream of random sample values. Pink noise passes that stream through Paul Kellet’s refined filter, a set of seven simple filters that tilt the spectrum down by about 3 dB per octave. Brown noise uses a leaky integrator, where each sample is mostly the previous one plus a little new randomness, which tilts the spectrum down by about 6 dB per octave.

For live playback the page makes four seconds of noise and loops it with the Web Audio API. For the export, the tool makes the full length in one go, scales it so the loudest sample sits at your Volume setting, adds a 50 ms fade at each end so it does not click, and writes a 16-bit WAV.

Worked examples

These come from the tool’s own export function.

• Default settings. Pink noise, volume 30%, 30 seconds gives pink-noise-30s.wav, about 2.5 MB.
• A long masking track. Brown noise for 600 seconds gives brown-noise-600s.wav, about 50.5 MB.
• A short test burst. White noise at 20% for 90 seconds gives white-noise-90s.wav.

Limits and tips

• Mono only. The export has one channel; players send it to both speakers.
• Long exports use memory. An hour of audio is built in the tab before it is saved, which can be slow on older phones. A shorter file looped in your media player works just as well.
• Keep the level low for sleep or long sessions, and take breaks when you use headphones.
• To shorten or soften a file, use the audio fade in/out tool, or turn the WAV into MP3 or M4A with the audio converter.