Green Noise, like the extreme point known as silence, is an extreme edge in the musical space. It is characterised only by its frequency spectrum ( colour ), and the rest is random noise.
Examples of green noise occur wherever many sources of sound are mixed together - hundreds of wheels on tarmac, thousands of leaves blown by wind, waves of water crashing.
Here are some simulations of green noise, obtained by mixing two identical copies of a sound recording, with one copy randomly offset by a few seconds. By "folding" the recording many times, information is quickly smoothed away leaving green noise. The noise retains the frequency spectrum of the source recording.This one was originally a music recording by Tom Waits
This one was originally an interview on the radio with two male voices