Free Tool
Press play. Mid-frequency pink noise centered around 500 Hz \u2014 the same range as wind, rain, and rustling leaves. Runs in your browser. Free forever.
Green noise
500 Hz
Web Audio API not available in this browser.
Sleep timer
Runs entirely in your browser. No sign-up, no download, no tracking.
Center frequency
500 Hz
Natural ambient range
Signal source
Pink
Bandpass filtered
Runs on
Device
100% local, no tracking
Here's the honest answer: there is no formal acoustic definition of green noise. Unlike white noise, pink noise, or brown noise \u2014 which are precise mathematical descriptions of power spectral density \u2014 green noise is a term that emerged from the sleep and wellness community, not from audio engineering.
What people generally mean by "green noise" is pink noise with its energy concentrated in the middle of the audible spectrum, roughly around 500 Hz. That mid-frequency range happens to match where most natural ambient sounds sit: wind through trees, rain on a soft surface, rustling leaves, distant water. You can think of green noise as "pink noise that sounds like the outdoors."
The generator on this page implements exactly that: we generate pink noise using Paul Kellet's algorithm, then apply a broad bandpass filter centered at 500 Hz with a Q of 0.7. The result is softer than white noise (which includes harsh high frequencies) and more textured than brown noise (which can sound like a distant waterfall).
Which color of noise is best for you depends on what you're trying to mask, what you find pleasant, and what your sleep environment sounds like.
| Type | Character | Best for |
|---|---|---|
| White | Hissy, bright, full-spectrum | Masking sharp sounds (keyboards, office noise) |
| Pink | Balanced, softened highs | General background, reading, focus |
| Green | Natural, mid-focused, outdoorsy | Sleep, meditation, masking mid-range noise (voices, thin walls) |
| Brown | Deep, rumbly, waterfall-like | Deep sleep, anxiety relief, low-frequency masking |
Try each one for a few nights before committing to a favorite. The "best" is highly personal and depends on your specific room acoustics.
Start it 5\u201310 minutes before you want to be asleep, at a low-to-medium volume. Use the sleep timer to fade it out after 30\u201360 minutes \u2014 once you're asleep, continuous sound can actually disrupt deeper stages.
Lower volume, no timer. Green noise is less distracting than white noise for deep work because the mid-frequency focus doesn't compete with speech and music cognition.
Voices travel in the 300\u20133000 Hz range \u2014 right where green noise peaks. It's particularly good at blurring muffled conversation through walls without needing the volume of a white noise machine.
Green noise's natural character pairs well with guided breathing. Lower volume than sleep use. Some people find it reduces mind-wandering without being as heavy as brown noise.
Green noise can help you fall asleep faster. But if you're then blasted awake by a standard buzzer 8 hours later, you undo most of the benefit in the first 30 seconds of your day.
That's why we built WakeMind. It pairs gentle evening audio with a four-stage morning wake sequence \u2014 gradual sound, voice greeting, affirmation, briefing \u2014 designed to transition you out of sleep instead of startle you out of it. The green noise generator above is free and will stay free. WakeMind is the paid product we make, and it's where the full bedtime-to-morning workflow lives.
Green noise is pink noise with its energy concentrated in the middle of the audible spectrum, around 500 Hz — the same frequency range where most natural ambient sounds like wind, rain, and rustling leaves sit. It's not a formally defined acoustic category (unlike white, pink, or brown noise) but the term has become popular in the sleep and focus community because the mid-frequency focus feels softer than white noise without being as low and rumbly as brown noise.
Many people find it more effective for sleep than white noise because it masks sudden noises in the mid-frequency range (voices, doors, thin-wall neighbors) without the harshness of the full white noise spectrum. There's no formal clinical research on green noise specifically, but the underlying research on broadband ambient sound for sleep onset is solid. If you find white noise abrasive or brown noise too dull, green is worth trying.
White noise is flat across all frequencies — hissy and bright, like an untuned TV. Pink noise rolls off the highs — softer and more balanced. Brown noise rolls off even further, emphasizing the low end — deep, rumbly, waterfall-like. Green noise sits between pink and brown with a bump around 500 Hz, mimicking natural ambient sound. Rule of thumb: white for masking keyboards, pink for balanced background, brown for deep sleep, green for natural-feeling ambience.
Yes, on any modern mobile browser — iOS Safari, Android Chrome, Firefox Mobile. Because of mobile browser autoplay policies, you'll need to tap the play button to start (we can't auto-start sound on a page load). Volume is controlled by your device's system volume plus the on-page slider.
Browsers aggressively throttle audio in background tabs to save battery. If you need continuous playback, keep the tab in the foreground, or use the WakeMind iOS app where audio runs as a proper background session.
No. The entire generator runs locally in your browser via the Web Audio API. No audio data is transmitted anywhere. No analytics are captured on play events. The only requests the page makes are the initial page load and standard site analytics (for pageviews — aggregated, anonymous). Your volume and timer preferences aren't stored.