Once upon a time, a
song was an
amorphous thing. Before
recording technology could
capture any one
performance, a
song was an
idea of how it should sound. You had a
melody and maybe some
harmony, possibly some
lyrics.
A song traveled from ear to ear as it was performed. It would change deliberately and also inevitably as each person heard it. New verses were invented, new flourishes were added; with each hearing, the song changed.
Even when written as sheet music, a song would be captured only partially, as an arrangement that represented one version. These could be authoritative, as with a score for an opera, or simply a record of what a tune sounded like in one place, at one time.
Recording technology, beginning with wax cylinders, altered the way human beings understand music. Never before could one afternoon's work set such an exact standard for the way a song should sound. Musicians began once more to improvise, using different instruments, developing themes sometimes beyond recognition. With the gramophone and the radio, however, came a musical monoculture with many identical copies of the same recording. All over the world, recorded songs sounded the same. Listeners became a sort of performer by tuning in or dropping a needle, a single act which produced a single repeatable sequence of sounds. One could adapt and improve that version, of course, but it would be different and somehow incorrect. Everyone knew what it was supposed to sound like.
As electronic music dawned, the song became an artifact for a very different reason. Synthesizers had to be tweaked for hours or even days to produce one particular sound. These sounds would then be spliced to produce, say, a Wendy Carlos album. This music could not be performed live. It was an artifact created by painstakingly assembling bloops and bleeps onto one unique object, the master tape, which could only be copied. The tune itself might be very old, as with Switched On Bach, but you couldn't tweak the decay of a particular note the way you could sustain a fermata.
Improvisation reacted with sampling. By isolating a sample of a musical artifact, musicians could quote each other, often out of context. As electronic instruments improved, live versions became possible again. Music became a little more fluid, and remixes flourished. One catchy song like Suzanne Vega's "Tom's Diner" could be altered, first in the famous remix by DNA, and then in an entire album of versions and translations.
With peer-to-peer sharing of compressed music in Ogg Vorbis, MP3, and similar formats, the song is again becoming more an artifact, more a trading card to collect than a legend to retell. Fortunately, editing and recording software is also within the reach of the amateur. The days of song as artifact may yet be limited.