What is your favorite color of noise: white, pink, brown, blue, violet, gray, or black?

You're probably familiar with white noise generators, which insomniacs often find useful as a sleep aid. White noise is a blend of random frequencies with a flat spectrum — any frequency band has the same amount of power as any other. I find white noise to be sharp and harsh.

Here's an example of white noise (warning — it's loud!)

Most white noise generators don't actually play white noise — they play a "colored noise" that's more soothing. Colored noises have a blend of random frequencies, but some frequencies play at a higher volume than other frequencies. This gives the noise a "color" or distinctive tone. Here are samples of some common colored sounds:

  • Pink noise differs from white noise — every octave contains the same amount of energy, rather than every frequency band like in white noise. It's not as sharp as white noise. It's richer, deeper. It sounds like a rushing river.
  • Brown noise's power drops as the frequency increases. It sounds like pink noise off in the distance. It's lush and chocolately. I find it to be the most pleasant of all colored noises.
  • Blue noise's signal power increases with higher frequencies. It sounds like air escaping from an inflated tire. It's startling rather than soothing.
  • Violet noise is like blue noise but the power increases more sharply as the frequency increases. It sounds like a thinner version of blue noise.
  • Grey noise is designed to fit a psychoacoustic equal loudness curve "giving the listener the perception that it is equally loud at all frequencies." I could probably fall asleep to grey noise, but it's not as velvety as brown noise.
  • Black noise is silence. Here's 10 hours of it.

Wikipedia has a good article about the colors of noise with examples for each one. 

This originally appeared in my newsletter, The Magnet.