I have Winamp set to load a new skin every time a new song plays—and it used to suck: I didn’t have a high enough cool skin / OK skin ratio. But now that I’ve downloaded cooler skins and deleted some I didn’t like, the visual vibe is much better, and at times can have a sort of symbiosis with the music. Listening to a bunch of tunes I hadn’t played in awhile, and Slava ended and the first notes of Chet Baker’s version of Autumn Leaves were accompanied by a beautiful blue skin. Perfect. Perfect. Perfect.
Despite all the changes in thought pattern over the centuries and across the continents, there have been a few constants. One of them is the fact of emotion being drawn through music and dance. Go wherever and whenever you want — New York in 1955, Vienna in 1780, Sydney in 589 B.C., and you’ll find, at the very least, singing and dancing of some kind. (In fact, some scientists have speculated that music may actually predate speech.)
There are non-universal but independently-popping-up patterns, as well: music is often used, for example, for spiritual purposes, from the Cathedrals of medieval Europe to the ceremonies of North American natives to Hendrix’s Church of the Electric Lady and Coltraine’s transcendant Love Supreme; often, as well, a song will tell a story, be it Homer’s Odyssey, Beethoven’s Symphonie Pastoral or Gangsta's Paradise (though that’s really more of a haiku).
It’s things like this that lead to the conclusion that music is somehow wired sidelong into our neural structure, like Asimov’s 3 Laws, that the patterns of chords and rhythms are created in ways that are parallel to the patterns in the way we think about ideas and experience emotions.
Of course, there’s a lot of elasticity in the way concepts are mapped into sounds — in fact, a tremendous amount, so much that it begs the question "how in the world did music then get started in the first place, with no environmental connection between, say, minor chords and sadness?" It’s important to remember that there is some underlying non-relative physicality — the shape of sound waves, for example, is not something purely in-the-mind but something definite: play two notes an octave apart and the sound wave that produces the higher note has a frequency exactly twice as great as the one that produces the lower note, which means that the even peaks of the high sound wave (every other peak, that is) line up with the peaks of the low sound wave, and the odd peaks (the remaining ones) line up with the troughs of the low sound wave — and to our ears, it’s easy to see why both notes are called C (or A, or E, etc., depending on which were played). A note with a frequency about 1.5 times that of the first (or 3-divided-by-2 times) is half an octave (or a fifth) higher, and one with a frequency 1.75 times that of the first (or 5-divided-by-four times) is three-quarters of an octave (or a minor seventh) higher. There are mathematical relations between other pairs of notes as well, and generally the more complex or distant the relation, the more dissonant the sound.
One thing common to almost all music is the buildup and release of tension — this often comprises a good portion of, if you will, the information content of the music. But not all music has the information stored in the same place: in traditional western music, it’s stored in the type of chord (and the changes between varying degrees of consonance and dissonance), which is the type of mathematical relationship between a few notes; in Latin music, it’s often the type of counterhythm placed against the main ongoing rhythm, which is the mathematical relationship between a few beats (which, come to think of it, can be thought of as notes scattered out in time — rhythms 1.5 times as fast are analogous to notes 1.5 times as high, and three beats per measure put against four is analogous to one sound wave put against another with a frequency 1.25 times higher). Other types of music store information in other locations still, and if you grow up hearing the information stored in one way, it’s often difficult to extract information stored in a different way, and the music sounds like noise (in the case of bebop to 1950s traditionalists) — or sounds satanic (in the case of punk rock to Christian fundamentalists). (In the case of misinterpretations like these, I suspect that the information content of the used-to music and the now-heard music may be different, but the interpretation is generally flawed as well. For example, speaking of differences in information content, Charlie Parker once said that "music is finding the beautiful notes," which is immediately reflected in his playing, and also is probably not how, say, Stravinsky would have defined it.)
Don’t ask me how a minor chord came to indicate sadness; I suspect, however, that the chord’s mathematical structure has some relation to the mathematical structure of the neural construct used to access that emotion. People who due to their lives develop different neural constructs will therefore create music with different mathematical structure (and, perhaps, the brains of people who listen to music during childhood — and, to a lesser extent, adulthood — will be nudged into forming the neural constructs parallel to that music).
To put it in cyberpunky terms that make me sound smart: music is encrypted thought and emotion that our brains learn how to decrypt (perhaps using some of the same processes used to decrypt language, which is, of course, encrypted thought and emotion of a different kind).