Decibel Shield
White noise generator › Brown noise
Brown noise generator
Brown noise is noise weighted to the low end: its power falls 6 dB per octave, so it sounds like a waterfall or heavy rain rather than the hiss of white noise. Press play to generate it in your browser, with nothing downloaded and no account, set a sleep timer up to eight hours, and measure how loud it really is in the room.
Weighted to the low end. A waterfall, or a jet heard from inside the cabin.
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.
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Brown, pink and white noise compared
A noise colour is the slope of the sound across pitch, in decibels per octave. Brown is the deepest of the common three; the white noise generator has all six, including grey, blue and violet.
| Colour | Slope | What it sounds like |
|---|---|---|
| Brown | −6 dB/octave | Weighted to the low end. A waterfall, or a jet heard from inside the cabin. |
| Pink | −3 dB/octave | Equal power per octave, so it sounds balanced rather than bright. Steady rain. |
| White | 0 dB/octave | Equal power at every frequency. The bright, even hiss of an untuned radio. |
Volume is not a decibel level
The slider sets digital volume. What reaches your ear depends on your phone, your speaker and how far away it is, so no website can know it. The measure button reads the room with the same maths as the decibel meter on this site. 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.
Questions
What is brown noise?
Random noise whose power falls 6 dB with every octave you go up, so most of its energy sits in the low frequencies. It sounds like a waterfall, heavy rain or the inside of an aircraft cabin rather than the bright hiss of white noise. The name comes from Brownian motion, the random drift of particles, not from the colour.
Is brown noise the same as red noise?
Yes. Red noise is another name for the same 6 dB per octave slope, used mostly in physics and signal processing. Brown noise is the usual name in audio and sleep apps.
Brown, pink or white noise: which is better for sleep?
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. The useful test is which one you stop noticing.
Does this download anything 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.
How loud should brown noise be?
Quieter than most people set it. A website cannot know the level at your ear, because the same slider produces very different levels on different devices and speakers, so measure it with the button on this page. NIOSH puts the occupational limit at 85 dB averaged over 8 hours, and a masking level should be far below that.