Blue noise
Only the highs, above about 4 kHz. Airy and crisp, best at a low volume or in a mix.
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
Blue noise is noise weighted toward the treble. What you hear is an airy, crisp hiss, like steam or a light spray, with no body underneath.
Strictly, blue noise rises by 3 dB per octave. Ours is a simpler, practical version: white noise with everything below about 4 kHz removed by a high-pass filter. It is generated live in your browser with the app's code, from a 30-second buffer with a crossfaded seam, and turned down to play as loud as the other sounds.
How people use it
Few people sleep to blue noise on its own. It is more useful in small doses: a quiet layer over brown noise or rain adds air and covers small, sharp sounds without making the whole mix bright.
High frequencies are tiring at volume, so keep it low. If it starts to feel shrill, switch to pink noise or turn the blue layer down further rather than turning everything up.
Questions
What is blue noise used for?
In audio and image processing it is used where you want randomness without low-frequency clumping. As a listening sound it is mostly a light, airy layer in a mix.
Is this true blue noise?
Not in the strict sense. True blue noise rises 3 dB per octave; this is white noise high-passed at about 4 kHz, which sounds similar and is simpler to generate.
Mix it with
Get blue noise on your phone
Nightwool is coming to iPhone and Android. One e-mail when it launches, then we delete the list.