October 1, 2013 @ Wikipedia
Different “colors” of noise have significantly different properties: for example, as audio signals they will sound differently to human ears, and as images they will have a visibly different texture. Therefore, each application typically requires noise of a specific “color”.
This sense of “color” for noise signals is similar to the concept of timbre in music (which is also called “tone color”); however the latter is almost always used for sound, and may consider very detailed features of the spectrum.
The practice of naming kinds of noise after colors started with “white noise”, a signal whose spectrum has equal power within any equal interval of frequencies. That name was given by analogy with “white light”, which was (incorrectly) assumed to have such a “flat” power spectrum over the visible range. Other color names, like “pink”, “red”, and “blue” were then given to noise with other spectral profiles; often (but not always) in reference to the color of light with similar spectra. Some of those names have standard definitions in certain disciplines, while others are very informal and poorly defined.
Find out more about and listen samples of the Colors of Noise @ Wikipedia