Writing in The New Yorker, Adam Gopnik notes, "Of all the amazing things the mind does, the most amazing may be that it can take sound and turn it into meaning. The rest of the double leaps the mind makes looks almost easy by comparison: we like pictures of babies at picnics in sunlight because, after all, in the world we like sunny days and chubby babies. The stories we tell in literature are like the lies we tell in life. But music is simply a set of physical vibrations that reach our eardrums; from those vibrations we make the emotional map of our lives" (Music To Your Ears, January 28, 2013).
The sound of music against the vibrating membrane of the eardrum is instantly organized by the brain not just into a stream of passing information but into an "auditory scene," a kind of dimensional space in which sounds are instantly separated, streamed, and regimented. As it turns out, Gopnik notes, the ear is a lot like what the Gestalt psychologists had found out years before about the eye - that it is a piece of the mind. The ear creates aural figures and aural backgrounds the way the eye makes figures and ground.
We store musical information in our head and manipulate it and play around with it. There seems to be two "systems" in the brain that respond to music. One is called veridical and responds to the pleasant sounds of the songs we already know. The other has been labeled sequential and anticipates the next note or harmonic move in an unfamiliar phrase of music. The sequential system is stimulated when music follows the logic of the notes or surprises us in some way that isn't merely arbitrary.
This has two interesting implications to me. First, that music that we experience is not really created by the performer so much as by the listener, who decodes all of the aural information entering the ears, synthesizes it, and reconstructs it as something called "music." Two person's experience of the same musical passage may be completely different, depending on how their individual minds process it. This is why some people can, say, love metal but hate opera, and vice versa.
Second, this ability to create music in our mind is obviously based on our own individual experiences, which is why some foreign musics can sound so unfamiliar and, well, non-musical at first. But as we start to develop some familiarity with new musics, we develop sets of mental templates of where notes should go, where they stop and start, and how the various lines are supposed to fit together. This helps explain some of the camaraderie among devotees of particular genres of music - people who's minds can create enjoyable music out of the complexity of orchestral proceedings or the simplicity of a strummed guitar have similar templates and likely similar past experiences, and are probably more likely to be compatible on a social or personal level than those with different sets of templates.
These mental templates, acquired during our lifetime of experience, are of course samskara, our mental formations, the "mental maps" of Erich Fromm. The Buddha recognized samskara as one of the aggregates that constituted the ego-self, as well as the necessary condition for the arising of ego-consciousness. As it turns out, they also are why we humans can hear and appreciate music while all other animals seem to regard our precious and beloved music as mere noise, with the possible exception of whales, whose music sounds so strange and foreign to our human ear-minds, as human and cetacean samskara must be quite different (if the latter even exists at all).
I have often asserted that all music, without exception, is a direct expression of the buddha-dharma. With this new understanding, this statement now seems more true than ever.