I'm just right now hearing a song on youtube, actually it is the full album of Psychic TV - Sugarmorphoses, but this particular song is already in several minutes and it is just some haunting sounds with dogs/wolves making their beastly sounds and it does not change too much. Somehow I find it interesting, but I think it is the intention of artists that do stuff like that to interact with different interpretations of sound than regular music, including the formation of images. Not that the formation of mental images and other types of creative imagination do not appear on music like classical, quite the contrary, but a classical piece almost never tries to convey images directly like experimental music does. The faculty of formation of images is always present, but experimental sounds do it more in your face. For example in this beastly sounds I can come up with several good atmospheres/images/dreams etc. that give a whole new experience to listening music. Again, it is a different proposal than classical.
So what I'm saying is this kind of music, and other experimental kinds too like noise, are to be taken as a different experience altogether.