White noise, pink noise, brown noise: which one for sleep?
All three are named after colours and look alike on paper. To the ear they are three very different sensations — and they are not for the same job at night.
White noise
equal energy at every frequencyThe hissiest of the three: a steady rush close to an untuned radio. Because it holds as much energy in the highs as in the lows, it covers sounds that carry — voices, a television through a wall, a dog.
The one to reach for against neighbours and street noise.
Pink noise
−3 dB per octaveEnergy falls off steadily towards the highs, which makes it fuller and less aggressive than white noise — close to steady rain, or wind in dense foliage. It is the most versatile, and the easiest to bear over several hours.
The right first try if you do not know what to pick.
Brown noise
−6 dB per octaveAlmost all the energy sits in the low frequencies: a dull rumble, like a distant waterfall or the airflow in a cruising aircraft. No hiss, so no listening fatigue, but weaker masking of high-pitched sounds.
The most restful for long, quiet listening.
How to choose in one night
If what wakes you is high-pitched — voices, a television, a bark, a creaking floor — white noise covers it best, because it holds as much energy as those sounds in the high frequencies. If it is the silence itself that leaves your thoughts looping, brown noise is gentler over long stretches: it sounds like distant airflow, without white noise's hiss. Pink noise is the sensible middle, the one you come back to when the other two tire you.
A simple test: set the volume just above the noise you want to mask, no higher. If you have to turn it up loud to hear it over your own thoughts, the problem is not the sound but the level — a steady noise at a low level works better than a loud one that becomes the nuisance itself.
Layering them under a natural sound
A steady noise on its own can feel mechanical. Many sleepers put it underneath, at low volume, below something with more texture: light rain, wind in the trees, a wood fire. The steady noise masks the outside world, and the natural sound gives you something to listen to. In Sleep.fm that mix takes two taps, and it saves so you can start it again the next evening.
Should the sound stop during the night?
Nothing says it has to play for eight hours. Most people fall asleep within the first twenty minutes; a 30-minute to 1-hour timer is enough, and a fade-out avoids the abrupt silence that wakes you. If you often wake in the night, continuous playback at low volume makes sense — that is the one case where “endless” is the right setting.
All three noises are in Sleep.fm
White, pink and brown noise, with seventeen other ambient sounds to layer. iPhone and Android, no account, no subscription — white noise is one of the four free sounds.
See the app