Noise Colors

Blue noise for sleep:
the bright mirror of pink

By Colin Shepard Hanson · September 2026 · 7 min read

Blue noise is broadband noise whose energy rises with frequency, by about 3 decibels per octave. It is the exact mirror of pink noise: pink loses 3 decibels per octave as pitch rises, blue gains them. The result is a fine, bright hiss with almost no bass underneath it.

It is the least common noise color in sleep apps, and for a reasonable cause: it puts its energy right where human hearing is most sensitive. But it has a specific job that no other color does, and it is the only answer for a small group of people that the usual colors leave cold. This guide covers what blue noise is, what it sounds like, how it compares with white, pink, brown, green and grey noise, and when it is actually worth using at night.

What is blue noise?

The colors of noise are named by how their energy is spread across frequency. White noise holds equal power at every frequency, like white light. Pink noise loses about 3 decibels per octave, brown about 6. Blue noise goes the other way: its power is proportional to frequency, so it gains about 3 decibels with every doubling of pitch.

Reading about it only goes so far: hear all six noise colors side by side, generated live in your browser.

That is a formal definition, the same kind of specification white, pink and brown have, rather than a loose description like green. The name follows the light analogy: light weighted toward high frequencies looks blue. Some references call the same sound azure noise. Violet noise, one step further, rises at 6 decibels per octave and is the derivative of white; blue is the derivative of pink.

Where blue noise actually gets used

Outside of sleep, blue noise is a well-known tool. Printers and screens use blue-noise patterns for dithering, because scattering error into fine, high-frequency detail is far less visible to the eye than letting it clump. Computer graphics uses blue-noise sampling for the same reason: points spread evenly, with no clusters and no gaps. The property that matters in both cases is the one you hear. Energy is pushed up to the fine end of the scale, with nothing coarse left behind.

What does blue noise sound like?

Blue noise has a recognizable character even though, like every noise color, it is random. Common descriptions include:

• A spray bottle or an aerosol can
• Steam escaping from a valve
• The fine hiss of a shower head, without the splash
• White noise with the body taken out and the air turned up

It should not sound like a tone. It is still broadband noise, just tilted. The most useful comparison is with white: if white noise is static, blue is the top half of that static on its own.

Blue noise vs white, pink, brown, green, and grey noise

Blue noise vs white noise

White is flat by measurement, and it already sounds bright to a person because the ear is most sensitive between roughly 2 and 5 kHz. Blue tilts further in the same direction. In practice it sounds like white with less body: the same hiss, more exposed. If white is too harsh for you, blue will be more so. If white sounds dull or muddy, which is the rarer complaint, blue is the correction.

Blue noise vs pink noise

They are opposites by definition. Pink is the color most people settle on for sleep, partly because its downward slope roughly follows the way hearing sensitivity falls away toward the treble, so it sounds balanced rather than bright. Blue is that slope reversed, and everything that makes pink comfortable over a night makes blue demanding.

Blue noise vs brown noise

Brown is all bass and blue is all treble, and they overlap almost nowhere. That makes them good at masking completely different things. Brown covers traffic, a boiler, footsteps through the ceiling. Blue covers a hissing pipe, a whining charger, birdsong. Neither one does the other's job.

Blue noise vs green and grey noise

Green concentrates its energy in the middle and rolls both ends off, so it has nothing in the range blue lives in. Grey is shaped to sound level at every pitch, which means it deliberately pulls back the region blue pushes forward. Of the six, grey is the natural fallback if blue turns out too sharp: it keeps some of the air without the tilt.

Is blue noise good for sleep?

For most people, blue noise is not the first color to try. Its energy sits where hearing is most sensitive, so at equal volume it feels louder and fatigues faster than pink or brown, and it does very little against low rumble.

There is no direct research on blue noise and sleep. The research on continuous noise in general is mixed: a 2021 systematic review rated the evidence that noise improves sleep as very low quality, and a 2022 review of auditory stimulation in adults found no strong overall effect, with a few individual studies reporting benefits. Nothing in that literature singles out blue noise, in either direction.

So the practical case is about masking, not sleep physiology. A noise color only covers what it overlaps. If what wakes you is high-pitched, blue can cover it at a lower total volume than white would need, because it spends none of its energy on frequencies the problem does not occupy.

Who may prefer blue noise?

Blue noise is worth testing if:

• The sound that disturbs you is itself high-pitched: a hissing radiator or pipe, a keyboard in the next room, the whine of a charger or a fridge, birdsong at dawn
• White noise sounds dull or muddy to you rather than harsh
• You are using noise to cover a high-pitched tinnitus tone, and darker colors leave it exposed
• You want a spray or steam texture without the rumble that comes with a fan or a shower

One note on tinnitus. Sound therapy for tinnitus is a real clinical practice, but a 2018 Cochrane review found the evidence that sound generators improve tinnitus to be of low quality, and nothing in it is specific to blue noise. If a brighter color is more comfortable than a darker one against a high-pitched tone, that is a comfort observation and worth acting on. Persistent tinnitus is worth taking to an audiologist.

How to use blue noise for sleep

Set it lower than any other color

Blue is at its most impressive in the first minute and its most wearing in the eighth hour. Start well below where you would set white, and raise it only until the specific sound you are covering stops registering.

Use a fade in and a timer

A bright hiss that seemed modest at bedtime can feel loud at 3am once the room has gone quiet around it. A slow fade in lets your ears settle before it reaches full level, and a sleep timer with a fade out avoids the 3am discovery altogether.

Cap the top

Textbook blue keeps rising to the edge of hearing, and almost nobody wants that last octave at sleeping volume. Lowering the cutoff keeps the character of the color while removing the part that fatigues. If it still feels thin, a little flat noise underneath gives it body without changing what it is.

How Veil generates blue noise

Veil does not play a recording of blue noise. It starts from the same filter cascade that produces its pink noise and takes the difference between each sample and the one before it. That operation is a differentiator, which rises at 6 decibels per octave, so applied to pink's 3 decibel fall it leaves a clean 3 decibel per octave rise: blue, by definition.

Two adjustments make it liveable overnight. A small amount of flat white noise is mixed underneath the tilt, which gives it body without changing its identity, since blue on its own has almost no low end. And a low-pass at 6 kHz caps the top octave, where the fatigue lives. Both are adjustable in real time, so if the default is too bright or too thin you can move it rather than switch colors.

Because the signal is synthesized on the device, those controls reshape the source itself. That is the difference between shaping a sound and picking a different file.

Frequently asked questions

What is blue noise?

Blue noise is broadband noise whose power rises with frequency at about 3 decibels per octave, the mirror image of pink noise. It sounds like a fine, bright hiss with very little bass.

Is blue noise good for sleep?

For most people it is not the first color to try, because its energy sits where hearing is most sensitive and it fatigues faster than pink or brown at the same volume. It can help when the sound disturbing you is itself high-pitched, since a color only masks what it overlaps. There is no direct research on blue noise and sleep.

What is the difference between blue noise and white noise?

White noise has equal energy at every frequency. Blue noise tilts upward by 3 decibels per octave, so it has less body and more air. Both sound bright, but blue is brighter and thinner.

Is blue noise the same as violet noise?

No. Both rise with frequency, but violet noise rises twice as steeply, at 6 decibels per octave, and is the derivative of white noise. Blue is the derivative of pink. Violet is mostly a test signal; blue is the gentler of the two and the one worth listening to.