Decibel Shield
Decibel meter › White noise generator
White noise generator
Six noise colours, generated in your browser rather than streamed, so nothing downloads and it keeps playing offline. Pick white, pink, brown, grey, blue or violet, set a sleep timer up to eight hours, and dim the screen to black. Then measure how loud it actually is in the room, which no slider can tell you.
Equal power at every frequency. The bright, even hiss of an untuned radio.
How loud is this actually?
The slider sets digital volume, which is not a decibel level — what reaches your ear depends on your device and speakers, so no website can know it. This one can measure it, because measuring is what the rest of this site does.
Decibel Shield for iPhone keeps a history of what it measures.
Last updated:
What the colours mean
A colour is the slope of the sound across pitch, in decibels per octave. It is the same idea as the decibel chart: a number describing sound, not a mood. Brown is the deepest and violet the brightest.
| Colour | Slope | What it sounds like |
|---|---|---|
| White | 0 dB/octave | Equal power at every frequency. The bright, even hiss of an untuned radio. |
| Pink | −3 dB/octave | Equal power per octave, so it sounds balanced rather than bright. Steady rain. |
| Brown | −6 dB/octave | Weighted to the low end. A waterfall, or a jet heard from inside the cabin. |
| Grey | loudness-shaped | Shaped so it sounds about equally loud across pitch rather than measuring equal. Often preferred for tinnitus masking. |
| Blue | +3 dB/octave | The mirror of pink, tilted upward. Thinner and airier. |
| Violet | +6 dB/octave | The mirror of brown. Almost all treble, close to tape hiss. |
Grey is the odd one out and deliberately carries no slope. It is shaped so it sounds about equally loud across pitch rather than measuring equal, which is an approximation of a loudness curve, not a power law.
Volume is not a decibel level
Every generator on the web gives you a slider. None of them can tell you what it produces at your ear, because that depends on your phone, your speaker and how far away it is. The only honest way to know is to measure the room, which is what the button above does, using the same maths as the decibel meter on this site.
It matters because masking noise runs for hours. NIOSH sets its occupational limit at 85 dB averaged over eight hours, and every 3 dB above that halves the safe time; the safe decibel levels page has the full table. A masking level should sit far below any of that. If you have pushed the volume up to cover a genuinely loud neighbour, the useful next step is not more noise but a record of theirs.
When the noise next door is the problem
Masking helps you sleep tonight. It does not fix a neighbour, a venue or a building site, and it is worth keeping the two separate.
- Log the noise for a complaint — dated readings with times, which is what a landlord or a city asks for first.
- Your city's noise ordinance — the quiet hours and the enforcement test, quoted from the code.
- Quiet hours in an apartment — where the building's rules and the city's differ.
Questions
Does this download anything or use data while it plays?
No. The noise is generated in your browser from a random source rather than streamed, so nothing is downloaded while it plays and it keeps working if your connection drops. That is also why it starts instantly and why there is no advertising break in the middle of the night.
What is the difference between white, pink and brown noise?
It is the slope of the sound across pitch. White noise has equal power at every frequency and sounds bright, like an untuned radio. Pink drops 3 dB per octave, so it has equal power in each octave and sounds balanced, closest to steady rain. Brown drops 6 dB per octave and is weighted to the low end, like a waterfall. Most people who say white noise and mean something soothing are describing pink or brown.
Which colour is best for sleeping?
There is no single answer, and anyone claiming one is guessing. Pink and brown are the usual preferences because the low end masks thumps and traffic without the hiss that keeps some people awake, while white masks a wider range including speech from a neighbouring room. Grey is often preferred for tinnitus. The useful test is which one you stop noticing.
How loud should white noise be?
Quieter than most people set it. The level that matters is the one at your ear over a whole night, and a website cannot know it, because the same slider produces very different levels on different devices and speakers. Measure it with the button on this page, then keep it low enough to mask the disturbance rather than drown it. NIOSH puts the occupational limit at 85 dB averaged over 8 hours, and a masking level should be far below that.
Is it safe to run white noise all night?
At a low level it is common practice. The risk is not the noise being continuous but the noise being loud: a level chosen to cover a shouting neighbour can sit high enough to matter across eight hours, which is precisely what the measurement on this page is for. Advice for infant sleep machines generally stresses keeping them well away from the cot and at a low volume, and this is not medical guidance.
Why are there no rain or ocean sounds?
Because those cannot be generated, only recorded, and recordings mean licensed audio files to download. Every colour here is computed in your browser, which is what keeps the page instant, offline-capable and free of any upload. Six colours done properly seemed more useful than a thin copy of a sample library.