Pink noise is random sound with equal power in every octave, which means its energy falls by 3 dB each time the frequency doubles. It sounds like steady rain, a waterfall, or wind moving through trees. Because human hearing is roughly logarithmic, pink noise is the color that sounds most evenly balanced from bass to treble, neither hissy like white noise nor muffled like brown.
The generator on this page makes pink noise live in your browser using the Web Audio API. It is free and open source, with no ads, no signup and no tracking. Since the audio is computed rather than played back from a file, it never loops. Use the sleep timer to fade it out overnight, or export a WAV if you need a file.
Free, no ads, no signup. Runs entirely in your browser.
The closest everyday comparison is rain on a roof, heard from indoors: there is bass in it, there is midrange, and there is a soft hiss on top, all in roughly equal measure. A waterfall at close range and a large ventilation system are also pink-ish. If you play white noise and pink noise back to back, white sounds thin and sharp, while pink sounds fuller and lower, though still clearly a hiss rather than a rumble.
Pink noise has enough energy in the speech range to cover conversations well, and enough low end that it does not become grating over long periods. That combination is why it is the default color on this site and on most sound machines. If you have ever fallen asleep to the sound of rain or a running shower, you already know what continuous pink noise does; the generator simply removes the drips and the variation and leaves the steady wash.
Pink noise has a power spectral density proportional to 1/f. Each octave, from 100 to 200 Hz or from 4 to 8 kHz, carries the same total power, so on a spectrum analyzer with logarithmic frequency bins pink noise draws a flat line. On a linear plot it slopes down by 3 dB per octave, or 10 dB per decade. It is sometimes called 1/f noise or flicker noise.
1/f behavior turns up all over nature: the timing of heartbeats, the flicker of a candle, river discharge, and the loudness fluctuations of most music. This is part of why pink noise sounds natural to us. It is also the standard test signal for tuning loudspeaker systems in rooms, because a flat pink response on a log analyzer means the system is balanced per octave. More on the physics page.
There is no simple filter that produces an exact 3 dB per octave slope, so this site uses the Paul Kellett method, which is the standard approach in audio software. White noise is passed through several first-order low-pass filters in parallel, each with a different time constant, and their outputs are weighted and summed. The stair-step of the individual filters averages out to a slope that stays within a fraction of a decibel of ideal 1/f across the audible range.
The filter runs inside an audio worklet on every sample, so the noise is continuous for as long as the page is open. There is no loop point, no compression artifact, and no repeated pattern to notice at three in the morning. This matters more for pink noise than for most sounds, because its midrange content makes a loop seam or an encoding artifact relatively easy to pick out once you have noticed it.
Pink noise is one of the two most popular colors for sleep, alongside brown. It works mainly by masking: a steady sound raises the floor so that a car door or a barking dog stands out less. A few small laboratory studies have gone further and played brief pink noise pulses timed to slow-wave sleep, reporting deeper slow waves and modest memory improvements in the following morning. Those studies used precise timing and small groups, so they do not show that continuous pink noise all night has the same effect.
What can be said with confidence is that many people fall asleep faster with a steady sound in the room, and that pink noise is a comfortable choice for it. If you find it slightly bright at night, move the color slider toward 3.5 to lean toward brown, or try the sleep presets.
The play button above loads Standard Pink, which is unmodified pink noise. The color slider sits at 3 for pink; values between 2 and 3 blend toward white, values between 3 and 4 blend toward brown. The grey toggle applies a perceptual EQ that lifts the extremes so the sound feels even at low volume. A slow pulse rate adds a gentle swell, which turns flat pink noise into something closer to waves.
Keyboard shortcuts cover the basics: space to play or pause, arrow keys for volume, number keys for the first nine presets. The sleep timer fades out rather than stopping abruptly. You can install the page as an app for offline use and copy the URL to keep your exact settings.
Most people prefer it. White noise puts half its energy above 10 kHz where it sounds sharp; pink noise spreads energy evenly across octaves and sounds like rain. There is no strong evidence that one color produces measurably better sleep than another, so the honest answer is to pick whichever you can ignore most easily.
Steady noise is commonly used in nurseries and is considered safe when kept quiet and placed away from the crib. Pediatric guidance generally suggests staying under about 50 dB at the child's ear, roughly the level of a quiet conversation. This site is not a substitute for advice from your pediatrician.
By analogy with light. White light contains all wavelengths equally. If you tilt the mix toward the long, red end of the spectrum you get pinkish light. Pink noise tilts the audio spectrum toward the low, bass end in the same way, but only halfway; tilting it further gives red or brown noise.
Quieter than you probably think. The aim is to raise the background so that sudden sounds are less noticeable, not to drown everything out. If you have to raise your voice to talk over it, turn it down. For overnight use, most people settle at a level where they forget it is on within a minute or two.
No. It is generated fresh on every sample by a filter running in your browser, so there is no file to loop and no seam. If you export a WAV, that file will loop wherever your player restarts it, but the sound from the generator itself is continuous for as long as you leave it running.