Pink Noise - The "1/f" structure of spectral brain dynamics
1/f noise, also known as flicker noise or pink noise, is a type of noise where the power spectral density is inversely proportional to the frequency. This means the noise power decreases as the frequency increases. 1/f noise is observed in various fields, including electronics, music, biology, and economics
James Keeler and Farmer demonstrated that a system of coupled logistic maps could produce fluctuations with a 1/f power spectrum. They showed that this occurred because the system continually tunes itself to stay near a critical point, a property that was later dubbed self-organized criticality by Per Bak. - Source