A person can have a specific idea, or emotion, that they want to try to convey auditorally. This involves lots of time and creative thought working with an experimental medium, exploring its possibilities, learning along the way about the ties and effects of sound on emotion. Often, compositions are recorded over and over again to achieve a final piece that best expresses the impression the person was trying to convey. Here are some of the characteristics i have found in certain types of experimental music. Recordings can be simple and plain, or layered and looped or manipulated.
Inorganic compositions make use of audio feedback, or other machine sounds.
The normal sense of rhythm can be, but is not very common. Increasing rhythm in the harsh compositions starts to lead toward Machine and Industrial musics. Noise compositons that can have steady, or abstract beats. Lots of feedback, noise machines. Vocals are sometimes used, but are more common in industrial.