White Noise   

Random noise or audio rate voltage which has equal energy per Hertz in the 20 - 20,000 Hertz range.
Rain, a shower, a waterfall, etc. are natural examples which resemble white noise. WHite noise tends to have a distinct high frequency colour to humans as half the energy is in the highest octave which we can perceive: 10,000-20,000 Hertz.
white noise