1/f noise
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1/f noise is a signal or process with a frequency spectrum such that the spectral energy density is proportional to the reciprocal of the frequency. 1/f noise, sometimes pronounced as one over f noise, is also called pink noise or flicker noise.
In particular, there is equal energy in all octaves. In terms of power at a constant bandwidth, 1/f noise falls off at 3 dB per octave.
The human auditory system, which uses a roughly logarithmic concept of frequency approximated by the Bark scale, does not perceive with equal sensitivity all audible frequencies. However, humans may still differentiate between white noise and pink noise with ease.
Graphic equalizers also divide signals into bands logarithmically and report power by octaves; audio engineers put pink noise through a system to test whether it has a flat frequency response in the useful spectrum.
Pink noise is a variant of white noise. Pink noise is white noise that has been filtered to reduce the volume at each octave. This is done to compensate for the increase in the number of frequencies per octave. Each octave is reduced by 3 decibels, resulting in a noise sound wave that has equal energy at every octave.
See also
- White noise
- Noise (physics)
- Brown noise
- Statistics
- Audio signal processing
- Self-organised criticality
- Fractal
- Colors of noise
External links
- A Bibliography on 1/f Noise (http://www.nslij-genetics.org/wli/1fnoise/)
- DSP Generation of Pink (1/f) Noise (http://www.firstpr.com.au/dsp/pink-noise/) - Detailed discussion of various algorithms, with code samplesde:1/f-Rauschen