White Noise Machine
Play white, pink and brown noise plus rain sounds to focus, relax or sleep — with what actually distinguishes the colours.
White noise puts half its energy in the top octave
White noise is defined as equal power in every hertz. That sounds neutral, and to a human ear it is the opposite of neutral — because hearing works in octaves, and each octave up is twice as wide in hertz as the one below it. 20–40 Hz spans 20 Hz; 10,240–20,000 spans nearly ten thousand.
So each octave carries double the power of the one beneath. Splitting the audible range into octave bands:
| Octave band | White noise | Pink noise |
|---|---|---|
| 20 – 40 Hz | 0.10% | 10.03% |
| 40 – 80 Hz | 0.20% | 10.03% |
| 80 – 160 Hz | 0.40% | 10.03% |
| 160 – 320 Hz | 0.80% | 10.03% |
| 320 – 640 Hz | 1.60% | 10.03% |
| 640 – 1,280 Hz | 3.20% | 10.03% |
| 1,280 – 2,560 Hz | 6.41% | 10.03% |
| 2,560 – 5,120 Hz | 12.81% | 10.03% |
| 5,120 – 10,240 Hz | 25.63% | 10.03% |
| 10,240 – 20,000 Hz | 48.85% | 9.69% |
48.8% of white noise lives in the top octave and 74.5% in the top two — roughly 5 kHz upward, which is exactly the range an ear reads as hiss. The bottom five octaves together hold 3.1%. White noise is not bright by accident or by bad tuning. It is bright by definition.
Pink noise is the one most people actually mean
Pink noise has power falling as 1/f, which works out to equal power in every octave — the second column above, flat to within 0.34 of a percentage point across every full band. That is the noise that sounds even rather than hissy, the noise engineers use to tune sound systems, and almost always what someone means when they ask for white noise to sleep to.
The gap between them is largest at the extremes. In the lowest octave pink carries about a hundred times what white does; in the highest, white carries five times what pink does. Same total power, distributed by two different definitions of "flat".
Neither is more correct. White is flat if you measure in hertz; pink is flat if you measure the way ears do. The reason it is worth knowing is that "white noise machine" is a category name rather than a specification — the commercial ones people find restful are usually producing something closer to pink or brown, whatever the box says.
If you are choosing between the settings above by ear rather than by name, that is the right way round. And if white sounds harsh to you, that is not a fault in your hearing or in the generator — you are correctly noticing that half of it is in the top octave.
How to use
- Pick a noise colour or sound.
- Set a volume low enough to be unobtrusive.
- Use a timer if it is for falling asleep.
- Try pink or brown if white noise feels harsh.
Frequently asked questions
What is the difference between white, pink and brown noise?
How energy is distributed across frequencies. White noise has equal energy at every frequency and sounds hissy and bright. Pink noise falls off as frequency rises and sounds balanced, like steady rain. Brown noise falls off faster still and sounds deep, like a distant waterfall.
Which one should I use?
Most people find pink or brown more comfortable for sleep, since white noise emphasises the high frequencies our ears are most sensitive to and can be fatiguing. There is no correct answer — trying each for a few nights is more informative than any recommendation.
Does it actually help with sleep?
The evidence is mixed rather than conclusive. It plausibly helps by masking sudden noises that would otherwise wake you, which is a real mechanism. Claims about improving sleep quality in a quiet room are on much weaker ground.
Is it safe to play all night?
At a low volume, for adults, generally yes. The caution worth knowing concerns infants: research has found some sound machines can produce levels high enough to be a hearing risk if placed close to a cot at high volume. Distance and low volume address it.
Why does it help me concentrate?
By masking irregular sounds — conversation particularly. Speech is unusually distracting because we process it involuntarily, and steady broadband noise makes it less intelligible and therefore easier to ignore. That is a well-supported effect, unlike broader productivity claims.
Does the audio get downloaded?
The noise is generated in your browser rather than streamed, so it uses no bandwidth once loaded and works offline. Nothing is transmitted and no account is needed.
🔒 This tool runs entirely in your browser. Nothing you enter is uploaded, logged, or stored.