View source for Grey noise

{{Short description|Random noise whose frequency spectrum follows a psychoacoustic equal loudness curve}}
{{distinguish|Internet background noise}}
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{{Listen|filename=Gray noise.ogg|title=10 seconds of grey noise|description=}}
{{Listen|filename=Inverse ITU-R 468 weighted "grey noise".ogg|title=Inverse ITU-R 468 weighted "grey noise"|description=}}
[[Image:Gray noise spectrum.svg|thumb|Grey noise spectrum]]
{{Colors of noise}}

'''Grey noise''' is random noise whose [[frequency spectrum]] follows an [[equal-loudness contour]] (such as an ''inverted'' [[A-weighting]] curve).

The result is that grey noise contains all frequencies with equal [[loudness]], as opposed to [[white noise]], which contains all frequencies with equal ''energy''. The difference between the two is the result of [[psychoacoustics]], more specifically the fact that the human hearing is more sensitive to some frequencies than others.

Since equal-loudness curves depend not only on the individual but also on the volume at which the noise is played back, there is no one true grey noise. A mathematically simpler and clearly defined approximation of an equal-loudness noise is [[pink noise]] which creates an equal amount of energy per octave, not per hertz (i.e. a logarithmic instead of a linear behavior), so pink noise is closer to "equally loud at all frequencies" than white noise is.<ref>{{cite web|url=http://www.acousticfields.com/white-noise-definition-vs-pink-noise/|title=White Noise Definition Vs. Pink Noise – Acoustic Fields|date=12 February 2014|publisher=}}</ref>  

== See also ==
* [[Colors of noise]]

==References==
{{Reflist}}
{{Noise}}

{{DEFAULTSORT:Grey Noise}}


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[[Category:Noise (electronics)]]