It doesn't seem to represent the spectrum; lows at the left, highs on the right. Instead, each bar seems random. I've always guessed it represents the raw MP3 data in some way.

It's probably FAQ'ed. I should search instead of trying to start conversation. I've RTFM'ed myself.
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FireFox31
110gig MKIIa (30+80), Eutronix lights, 32 meg stacked RAM, Filener orange gel lens, Greenlights Lit Buttons green set