I was aware of white noise, but I didn’t realize there is a range of noises associated with colour:
Both pink and white noise are members of an entire color family of sound including black and brown noise. Sounds are assigned these colors based on how energy is distributed over several frequencies, according to Healthline.com. White noise, for example, is comprised of energy that is equally distributed across all audible frequencies. Brown noise, sometimes called red noise, consists of higher energies at lower frequencies—think thunder and deep, roaring sounds.
Pink noise, on the other hand, is a shade deeper than white noise. It’s similar to white noise in that it includes all audible frequencies; however, unlike white noise, energy is not distributed equally among them.
I have found that the rain sounds I listen to are more pink noise than white noise, and I prefer it for sleeping. If you are having trouble sleeping or relaxing, try listening to some pink noise.
For more on it, see: Pink Noise Sleep Benefits | Apartment Therapy