White Noise Generator (Pink & Brown Noise)

This generator plays three kinds of steady noise and lets you set the volume and a sleep timer. White noise has equal power at every frequency, so it sounds bright, like a hiss or radio static. Pink noise loses 3 dB of power per octave, which gives every octave the same energy; to most ears it sounds softer and more natural, closer to rain or wind. Brown noise loses 6 dB per octave and is mostly low rumble, like a distant waterfall or the inside of an aeroplane.

The sound is generated in your browser: each colour is a 12-second buffer per ear, with the two ears independent so it sounds wide rather than coming from one point, and the loop is cross-faded so there is no click where it repeats. Pink noise uses a well-known filter that stays within a fraction of a decibel of the ideal slope across the audible range, and brown noise is white noise passed through a very low one-pole filter. All three are set to the same average level, so switching colour does not jump in loudness.

People use steady noise to mask distracting sounds, help with falling asleep, settle babies or keep focus in a noisy room; it is also handy for checking speakers and headphones. Keep the volume modest: long exposure to loud sound can damage hearing, and for infants guidance suggests keeping a noise machine well away from the cot and at a low level. The sleep timer fades the sound out over its last 10 seconds. Playback can stop when a phone locks or the browser puts the tab to sleep, which is a limit of browsers rather than of the noise. A download writes a stereo WAV of 10, 30 or 60 seconds at the full common level, for use in other players.