Noise generator.
White, pink, brown, green and violet noise, generated live on your device rather than streamed — so it starts instantly, costs no data, and never buffers in the middle of the night. Pick a colour, set a volume you could talk over, and give it an auto-stop if you are using it to fall asleep.
No headphones needed — noise is not a binaural effect, so speakers are fine and often better for masking a room. Keep it at conversation level or below; the point is to cover a distraction, not to replace it with a louder one. Nothing is streamed: the audio is a four-second loop generated in your browser, so it works on a bad connection and costs no data. If you want a brainwave beat instead, or a noise bed underneath one, that is the main generator.
Which colour should I use?
Match the noise to the sound you are trying to cover. Masking works by spectral overlap: a noise only hides a distraction if it has energy in the same frequency range. That single idea decides almost every choice on this page.
| Colour | Spectrum | Sounds like | Best at masking |
|---|---|---|---|
| White | Flat — equal energy per hertz | Untuned radio static, a harsh hiss | Broadband distraction; the most common default and the most fatiguing |
| Pink | −3 dB per octave | Steady rain, wind in trees | General-purpose masking. Sounds “flat” to human ears because our hearing is not flat |
| Brown | −6 dB per octave | A waterfall, distant surf, a jet cabin | Low-frequency intrusion — snoring, traffic, a neighbour’s bass |
| Green | Mid-focused, centred near 500 Hz | A river, a moving stream | Nothing in particular; chosen because people find it pleasant rather than for coverage |
| Violet | +6 dB per octave | A sharp, airy hiss | High-frequency material; sometimes used in tinnitus masking, where the tone is often high |
Three practical consequences. For a snoring partner, use brown, not white — snoring is low-frequency and white noise puts most of its perceived energy above it. For an office or a café, pink is usually the better default, because white’s brightness becomes tiring over hours. For sleep, use the least noise that works, and consider the auto-stop rather than running it all night. The noise colours guide goes through each one properly, and there are individual pages for white, pink, brown and green.
How the colours are made.
Every colour here starts as white noise and is filtered. Nothing is a recording, which is why the file size is zero and the sound never loops audibly in a way you can pick out.
White noise is the raw material: a stream of random values with, on average, equal energy at every frequency. Everything else is a transformation of it. Pink comes from a filter that rolls the spectrum off at 3 dB per octave — the implementation here is Paul Kellet’s refined filter, a standard in audio software. Brown is white noise integrated over time with a small leak, which produces the 6 dB-per-octave slope and the deep, rounded character. Violet is the mirror image: the difference between consecutive samples, which lifts the top end by 6 dB per octave. Green is white noise pushed through a state-variable bandpass centred near 500 Hz, which is what gives it the moving-water quality.
The player builds a four-second buffer once, then loops it. Four seconds is long enough that the repeat is not perceptible in noise — there is no melody or transient for your ear to latch onto — and short enough to generate instantly. Switching colours rebuilds the buffer and swaps it without stopping the audio.
On the evidence: acoustic masking is uncontroversial — covering a sound with another sound demonstrably makes the first harder to hear. The claims that go beyond that are weaker. Reviews of noise for sleep generally find the trials small, short and inconsistent, and continuous overnight exposure is not risk-free at higher volumes. Treat noise as a tool for a specific problem rather than a nightly habit, and keep the volume down.
Volume, timers and headphones.
Set it just loud enough to blunt the distraction, not to erase it. The instinct is to turn noise up until the intrusion disappears completely, which usually means the noise itself is now the loudest thing in the room.
- Volume. A useful test: you should still be able to hold a conversation over it without raising your voice much. If the noise is the loudest thing you can hear, it is too loud — and continuous exposure at high levels over a whole night is a real consideration, not a theoretical one.
- Auto-stop. If you are using this to fall asleep, the timer is usually the better choice: it covers the part of the night when you are trying to drop off and then leaves you alone. Set it to 30 or 60 minutes.
- Speakers over headphones for sleep. Noise needs no stereo separation, so a speaker across the room is both more comfortable and safer than sleeping in earbuds. This is the opposite of the advice for binaural beats, where headphones are mandatory.
- Placement. Between you and the noise you are masking, if you can. A speaker on the wall nearest the source works better than one by your head at the same volume.
- Children. Infant sleep machines have been measured at levels high enough to be a concern at close range. If one is in a nursery, keep it well away from the cot and well below maximum.
Nothing here is stored or streamed. The audio is generated in your browser, so it works offline once the page has loaded, uses no bandwidth, and no account is involved.
Things people reasonably ask.
What is the best noise colour for sleep?
Brown or pink for most people. Brown has the most low-frequency energy, which is what masks traffic and snoring; pink is gentler than white over a long stretch. White works but many people find it harsh after an hour. There is no colour that is best for everyone — try one, and change it if it irritates you.
What noise blocks out snoring?
Brown, in most cases. Snoring is a low-frequency sound, and brown noise has by far the most energy down there, so it overlaps and masks it. White noise puts most of its perceived energy above the snore and covers it less well at the same volume.
What is violet noise for?
Violet is white noise tilted upward by 6 dB per octave, so it is very bright and thin. It is sometimes used in tinnitus masking, because tinnitus is often perceived as a high tone and violet has energy up there. It is not a treatment, and for most masking jobs it is the wrong choice — see binaural beats and tinnitus for what the evidence does and does not show.
Is it safe to run noise all night?
The volume matters more than the duration. Continuous sound at high levels through a whole night is worth avoiding, and infant sleep machines in particular have been measured at levels that give audiologists pause at close range. Keep it quiet, keep the speaker away from your head, and use the auto-stop if you only need help falling asleep.
Do I need headphones for noise?
No. Noise is not a binaural effect, so there is nothing that needs to reach each ear separately. Speakers are usually better, especially for sleep, because they are more comfortable and let the sound fill the room you are trying to mask.
Is this streaming audio?
No. The noise is generated by your browser from a four-second buffer, so it starts instantly, uses no data, and keeps working if your connection drops. Nothing is uploaded and there is no account.
Can I play noise and a binaural beat together?
Yes, in the main generator, which layers a white, pink or brown bed under the tone. The mobile app adds 34 ambient beds across seven categories.
What is the difference between white and pink noise?
White noise has equal energy at every frequency, which our hearing perceives as bright and hissy because we are more sensitive to high frequencies. Pink rolls off at 3 dB per octave, which compensates for that and is why pink sounds “flat” and more like rain. Same randomness, different spectral tilt.