If we are to consider translating music to image, it is perhaps useful to first examine what makes music "Music". Is music inherently tied to the act of hearing, or it is a more universal property which is most commonly experienced through hearing?
Music is not about hearing any more than language is.
This statement by Ruth Montgomery is representative of a movement within the deaf community to challenge the conventional assumption that music has no role or place in the life of one who does not hear. She argues that music plays an important role in cognitive development, and that the simplistic assumption that music is irrelevant to the deaf puts deaf children at an unconscionable cognitive disadvantage.
At some other extreme of the notion of music, Steven Pinker famously announced that music is "cheesecake for the mind"
"Compared with language, vision, social reasoning, and physical know-how, music could vanish from our species and the rest of our lifestyle would be virtually unchanged. Music appears to be a pure pleasure technology, a cocktail of recreational drugs that we ingest through the ear to stimulate a mass of pleasure circuits at once"
Not only is Pinker denigrating music, in an arbitrary manner that seems unique to certain kinds of academics, he is also implicitly stating that music is of a completely different nature than visual experience; that it does not participate in a shared cognitive space with language, vision, etc. I disagree strongly on all counts.
I once had a very strong cognitive experience of music. I was reading Russell Hoban's novel "The Medusa Frequency". In one passage, a kind of musical soundscape is briefly described. On reading it, I had an immediate sense of this music, although I found that I had no way to transcribe the sense of it into an actual piece of music. Certainly the idea of this music played upon my memory of various musical experiences, but not strongly enough to suggest a way of realizing it; it had tied into my sense of music without tying into any particular example.
In fact, it attached itself more strongly to a visual experience I had previously had watching cellular automata systems on my computer. Cellular automata are simulations of large groups of identical simple organisms who respond to their local environment with patterns whose complexity belies the simplicity of their behavioural rules. On seeing these automata systems play themselves out, I was immediate seized with the notion that these forms would translate very nicely into sound or music. But all my attempts to take what felt like very musical visual patterns into sound were deeply unsatisfying. The passage in Hoban's novel seemed to point to the same kind of music that the patterns of the automata suggested to me.
These experiences suggest to me that there is a quality of musicality which transcends any particular sensory modality, and that there may indeed be musics that are more successfully expressed visually than sonically. I am not making conclusions here, just opening questions that will be relevant to this exploration.
On the other hand, it is hard to ignore the powerful visceral and emotional impact that the experience of hearing music can have. This aspect of hearing music does not seem based in cognition, at least not in the sense I have discussed it above. It is not surprising that many attempts to visualize music have tended towards the psychedelic as a way of reflecting the state of intoxication that music can induce. Spiritual, uplifting, dionysian, euphoric... A process of translating music must also attempt to include these dimensions of musical experience.