I think that timbre is probably one of the most interesting parts of the sound spectrum. It is hard to describe because it is subjective. What does an oboe really sound like compared to a clarinet? What makes them distinguishable from one another? Timbre is so interesting because the range of sound is so large and varied.
Synethesia is something I think definetly exists because when I closed my eyes while listening to some of the Stockhausen music, I could see different pictures. For example, he made these sounds that were like droplets of water while he changed the intensity of the noise. I closed my eyes and was able to see water dropping into a puddle in rythm with what I heard. It was quite unusual to experience this, though it definitely let me see the originality and intrigue of this music. Though there was not a particular form, the music acheived its goal.