There are different approaches to noise in electronic music. Technically, noise is described as an equal amount of output in all present frequencies ('White Noise') and sounds pretty boring. People tend to mix their original signals with fragments of noise to get a more individual, maybe more haptical sound; on the other hand, a lot of strictly experimental music uses noise as the main source of audio, shifted in frequency and amplitude, fed back to the machines or distorted and delayed. Read more on Last.fm