Pink noise

Colors of noise
For the album by Laura Mvula, see Pink Noise (album).
This article is about 1/f noise. For quantum 1/f noise, see quantum 1/f noise.
"Fractal noise" redirects here. For the novel, see Fractal Noise.
A two-dimensional pink noise grayscale image, generated with a computer program; some fields observed in nature are characterized by a similar power spectrum[1]
A 3D pink noise image, generated with a computer program, viewed as an animation in which each frame is a 2D slice

Pink noise, 1⁄f noise, fractional noise or fractal noise is a signal or process with a frequency spectrum such that the power spectral density (power per frequency interval) is inversely proportional to the frequency of the signal. In pink noise, each octave interval (halving or doubling in frequency) carries an equal amount of noise energy.

Pink noise sounds like a waterfall.[2] It is often used to tune loudspeaker systems in professional audio.[3] Pink noise is one of the most commonly observed signals in biological systems.[4]

The name arises from the pink appearance of visible light with this power spectrum.[5] This is in contrast with white noise which has equal intensity per frequency interval.

  1. ^ Cite error: The named reference Field-1987 was invoked but never defined (see the help page).
  2. ^ "Glossary: Pink Noise". Sound on Sound. Retrieved November 22, 2022.
  3. ^ Davis, Gary; Jones, Ralph (1987). The Sound Reinforcement Handbook. Hal Leonard. p. 107. ISBN 0-88188-900-8.
  4. ^ Szendro, P (2001). "Pink-Noise Behaviour of Biosystems". European Biophysics Journal. 30 (3): 227–231. doi:10.1007/s002490100143. PMID 11508842. S2CID 24505215.
  5. ^ Downey, Allen (2012). Think Complexity. O'Reilly Media. p. 79. ISBN 978-1-4493-1463-7. Visible light with this power spectrum looks pink, hence the name.