Brown noise
Most of the energy sits low. A deep, rounded rumble with almost no hiss.
Timer
Generated in your browser with the same code as the app, nothing to download. Start with your volume low. Keep this tab open.
About this sound
Brown noise (also called red or Brownian noise) falls by about 6 dB per octave, so most of its energy sits in the low end. It sounds like a deep, rounded rumble, closer to distant surf or a jet engine heard from inside than to static.
It is generated in the browser with the same code as the app, as a random walk: each sample takes a small random step from the last one and leaks 2 percent back toward zero, so it never drifts off. That simple integrator is what pushes the energy down into the bass. The result plays from a 30-second buffer with a crossfaded seam, level-matched to the recordings.
How people use it
Brown noise is the usual pick for low rumble: traffic, trucks, a neighbor's bass, or the lower range of a partner's snoring. People also use it for focus, and some people with ADHD say it helps them; that has not been studied for brown noise specifically.
Because it is soft, it is easy to turn up too far. Keep it low and let it sit under the room. It is a good base for a mix: in the app's ready-made Rainy Night mix it sits quietly under rain, and Deep Focus pairs it with a fan.
Questions
Is brown noise good for sleep?
There is no good evidence that one noise color beats another for sleep. Brown noise is better than white at covering low rumble, and many people find it the calmest of the three.
Does brown noise help with ADHD?
It has not been studied. The research is on white noise and one study of pink noise, with small effects. If you want to try it, compare work blocks with and without it.
What is the difference between brown and deep brown noise?
Deep brown is the same noise with everything above about 200 Hz filtered away, so it loses the last bit of hiss and becomes mostly a low hum.
Get brown noise on your phone
Nightwool is coming to iPhone and Android. One e-mail when it launches, then we delete the list.