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What is green noise, and does it help you sleep?

Green noise has no standard definition: explainers place it anywhere from 500 Hz to 5 kHz. What it usually sounds like, what the research says, and who might like it.

By Michal Piják9 min readHow we write these guides

Illustration: a bedroom at night with an empty made bed and a small amber lamp, beside an open window onto a misty moonlit meadow and a dark forest edge
Illustration: Nightwool (AI-assisted)
On this page
  1. What green noise is
  2. Does green noise help you sleep?
  3. Where a midrange sound makes sense
  4. Where it won’t help much
  5. How to try green noise
  6. Questions
  7. Sources

This article is general information, not medical advice. If sleep, hearing or a health problem worries you, talk to a doctor or audiologist.

Green noise is noise with most of its energy in the middle of the range we hear, with the deep bass and the high hiss turned down. That is about as far as anyone agrees. Unlike white or pink noise, green noise has no standard technical definition, popular explainers place its center anywhere from 500 Hz to around 3 kHz, and no published study has tested it for sleep.

That doesn’t make it useless. Plenty of people find it easier to listen to than white noise, and a steady midrange sound has some sensible uses at night. This article explains what green noise is, where the name comes from, what the research can and can’t tell you, and how to decide if it’s for you.

What green noise is

Noise colors describe how a sound’s energy is spread across frequencies, from low (bass) to high (treble). A few of them have formal definitions. The ATIS Telecom Glossary, which carries on the old US federal telecommunications standard, defines white noise as having “equal power per hertz”, pink noise as “equal power per octave”, and blue noise as power that rises with frequency. That’s why white noise sounds bright and hissy, pink softer, and brown noise, which drops off faster still, deep and rumbly. Our guide to white, pink and brown noise explains those three in detail.

Green noise isn’t in that glossary at all. It’s an informal name for a band in the middle: think of white noise with the lowest and highest parts filtered out. The name plays on the idea that green sits in the middle of the visible light spectrum, just as this noise sits in the middle of the audible one.

Nobody agrees on where the middle is

Look up green noise and you’ll find quite different numbers:

  • The Sleep Foundation describes it as noise that “amplifies mid-range frequencies with uniform intensity” without giving a frequency.
  • A blog from the sleep app Relax Melodies says green noise has “frequencies around 500Hz”, and later on the same page describes a window between 500 and 5,000 Hz.
  • Another explainer gives 500 to 5,000 Hz as the range.
  • The mathematician John D. Cook, mapping the light spectrum onto a scale of hearing, put green noise “in the range of 1612 to 2919 Hz.”

Those are not small differences. A band around 500 Hz sounds warm and close to pink noise; a band around 2 to 3 kHz sounds much brighter. Two tracks both called “green noise” can sound like different sounds, which may explain why people disagree so much about whether they like it.

Green noise in Nightwool

Since there’s no standard, here is exactly what ours is. In Nightwool, green noise is white noise generated on your phone and passed through a gentle band-pass filter centered at 1 kHz. Most of its energy falls roughly between 500 and 2,000 Hz, with the edges sloping off rather than cutting out, so there is still some low and high sound in it. That puts it in the middle of the definitions above: brighter than the “around 500 Hz” versions, darker than the 2 to 3 kHz ones.

White, green and pink noise, generated in your browser the same way the app makes them. Green is white noise filtered to a band around 1 kHz. Start with your volume low.

How it compares with the other colors

Here is how the noise colors line up, using the versions in the app as the example. The descriptions of how they sound are general impressions, not measurements, and other apps and videos may tune theirs differently.

Color Where the energy sits How it tends to sound
White Equal across the whole range Bright, hissy, like radio static
Pink Turned down gradually toward the highs Softer, often compared to steady rain
Brown Mostly low A deep, rounded rumble with little hiss
Deep brown Brown with almost everything above about 200 Hz removed A low hum you feel as much as hear
Green A band in the middle, around 1 kHz A steady whoosh, thin at both ends
Blue and violet Only the highs, above about 4 and 6 kHz Airy, fine hiss

The point of the table is that green is the only one of these that removes both ends at once. Every other color keeps either the bass or the treble. That is what makes it sound “lighter” than brown and “rounder” than white, and it’s also its main limitation, covered below.

What to listen for when you compare them: whether a sound gets tiring after ten minutes (often the highs), whether it feels like pressure (often the lows), and whether you can still hear the thing you’re trying to cover.

The other green noise

The term also has a technical meaning in a completely different field. In 1998, engineers working on printing described “green-noise” halftoning: a way of arranging ink dots in small clusters so that prints hold up better on imperfect printers. It has nothing to do with sound or sleep, but it’s why a search for green noise in scientific databases turns up mostly papers about printers.

Does green noise help you sleep?

There is no direct evidence either way. A search of PubMed, the main database of medical research, for “green noise” turns up a dozen papers about printing, physics and electronics, and none about sleep. A 2022 review of sound-based sleep aids that covered white, pink and other colored noise doesn’t mention green noise once. The Sleep Foundation, which has a page promoting it, also says “there is limited research that shows green noise benefitting sleep.”

So anything said about green noise and sleep is borrowed from research on steady noise in general. That research is weaker than most people expect:

  • A 2021 systematic review of 38 studies rated the evidence that continuous noise improves sleep as very low quality.
  • A 2022 review of 34 studies found no strong evidence either way, and no reported harm from short-term use.
  • A careful 2026 sleep lab study found that pink noise at 50 dBA reduced brief wake-ups from aircraft noise, but also reduced REM sleep by about 19 minutes in people who don’t normally sleep with noise.

What noise of any color can do is masking: a steady sound makes sudden ones stand out less, so they’re less likely to wake you. Whether green noise does that better or worse than other colors depends on what you’re trying to cover, which is the more useful question.

Where a midrange sound makes sense

Voices and TV through the wall

Speech has most of its raw energy fairly low, peaking around 480 Hz in one study of long-term speech recordings. But the parts that let you understand words sit higher: studies of which frequency bands matter most for speech typically find a peak around 1 to 3 kHz. And what keeps people awake when they hear voices is often not the volume but the brain trying to follow the words.

A band around 1 kHz has energy right where that matters, without the sharp top end of white noise. That makes green noise a reasonable thing to try against a TV in the next room or voices from the hallway. White and pink noise also cover this range, so it’s a matter of which sound you’d rather listen to.

When white noise is too harsh

Our ears are most sensitive between about 2 and 5 kHz. White noise has a lot of energy up there, which is why many people find it harsh after a while. Green noise turns that region down, and many people describe it as calmer. If you like the idea of white noise but not the hiss, green or pink noise are both worth trying.

When brown noise is too heavy

Brown noise puts most of its energy in the bass. Some people love that; others find it boomy or feel it as pressure. Green noise leaves the bass thin, which some people prefer, especially at low volume on a small speaker.

Where it won’t help much

Green noise is a poor choice against low sounds. Hearing has a lopsided rule here, called the upward spread of masking: low sounds mask higher ones well, but high sounds mask low ones poorly. A band centered around 1 kHz has little energy in the bass, so it does little against:

  • footsteps from upstairs, bass through the wall or a slammed door
  • traffic rumble, trucks and buses
  • a partner’s deep snoring

For those, brown or deep brown noise, earplugs or changes to the room usually do more. Our article on noisy neighbors at night goes through the options.

Is it really the sound of nature?

You’ll often read that green noise is “the background noise of the world” or sounds like nature. No study supports that. Natural sounds vary a lot: a 2022 review of sound-based sleep aids describes most natural sounds, such as wind, rain and flowing water, as part of the white noise family, and its analysis of a rain recording looked like pink noise, not a midrange band. If you want nature, a recording of rain, a river or the sea will sound more like nature than any filtered noise. Some people like green noise precisely because it is simpler than a recording: nothing changes in it.

How to try green noise

If you want to see whether it suits you:

  1. Compare at the same volume. Listen to white, green and pink noise one after another, at a low level, from where you lie. Louder sounds seem better at first, so match them by ear.
  2. Keep it quiet. A level about that of a quiet conversation, or lower, is enough for most people. Put the speaker across the room, not by your pillow. Our article on whether white noise is safe every night covers volume in more detail.
  3. Give it a few nights. A new sound can feel odd on the first night simply because it’s new.
  4. Mix if one sound isn’t enough. Green noise with a low sound under it, like brown noise or a fan, covers more of the range than either alone.
  5. Use a timer if you only need help falling asleep. A slow fade-out is less noticeable than a sudden stop.

If you have tinnitus, a midrange band may help or may not, depending on the pitch of your tinnitus. Our guide to sounds for tinnitus explains how to choose, and why it’s worth seeing an audiologist.

Questions

What does green noise sound like?

Like a steady whoosh without the sharp hiss of white noise or the deep rumble of brown noise. Explainers often compare it to a distant waterfall or wind, though it depends a lot on how a particular track was made.

Is green noise better than pink or brown noise for sleep?

Nobody knows, because no study has compared them for sleep. Pink and brown noise reach further into the bass; green noise leaves both ends of the range thinner. Choose by ear, at a low volume, and give a new sound a few nights.

Is green noise the same as nature sounds?

No. It is a marketing description, not a scientific one. Recordings of rain or wind have their own uneven, changing spectrum, and a 2022 review found rain closer to pink noise than to any midrange band.

Is green noise safe for babies?

The same rules apply as for any sound machine: keep it quiet, keep the speaker well away from the crib and check the level at the crib (researchers use 50 dBA, the hospital nursery limit, as a reference). There is no research on green noise for babies specifically. More in our guide to white noise for babies.

Sources

Michal Piják, Founder of Nightwool

Michal is an independent developer in Bratislava, Slovakia, and builds Nightwool on his own. He writes these guides from published research and official health guidance, and links every source so you can check it.

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