Handy Charts

Definition of Noise Colors

Noise Color	Noise Energy
White Noise	Equal amount of energy in all frequency bands
Grey Noise	White noise weighted to sound equally loud to the human ear at all frequencies
Purple Noise	Energy increases at 6 dB per octave Has the most energy in the higher frequencies
Blue Noise	Energy increases at 3 dB per octave
Green Noise (Unofficial)	The mid-frequencies of white noise “The background noise of the world”
Orange Noise (Unofficial)	Noise stripped of harmonious frequencies
Pink Noise	Energy decreases at 3 dB per octave Contains the same SPL in each octave band
Red Noise	Energy decreases at 6 dB per octave Ambient underwater noise from distant sources (oceanographic term) The same as brown noise
Brown Noise	The kind of the signal noise produced by brownian motion The same as red noise
Black Noise	Silence or silence with an occasional spike