White Noise

What you get after a TV station is blown up.

Mathematically speaking, white noise is about as simple as it gets. It is a random signal with a constant power spectral density. With a finite sample rate, it can be approximated using random amplitudes over a uniform distribution. Sonically, it is best described as a hiss. Loud or long-duration white noise can be obnoxious and slightly painful, which isn't a bad thing depending on the artistic context.