This has been discussed before, but I'll summarise (use search for the full thread).
When music is mixed to form a track, the combination of sound frequencies are all mashed together such that they become inseparable. Thus for you to look at the sound wave and say, "that's a guitar" or "that's a flute" would be next to impossible if you didn't know the instruments or their frequency ranges to start off with. With games like RB and GH, the tracks are manually developed by hand, often with studio mixes and scores provided by the record label. When you play the consumer version of a track you get just a single sound wave (per channel, so for stereo, two in total). The way AS works, is by looking for the intensity and frequency peaks within this sound wave. Separating out single instruments is not possible. I can explain more about how the music looks to a computer, PM me. If you want to know how the tracks are mixed to form consumer level music, then Passerby who's pretty clued up on this would be your best bet.
