I asked about this in the past, but never received a straight response. I noticed a new "whine" at both low and high RPM within what are the usual supercharger sounds. It was the supercharger belt and pulley (belt was notably slack on manual inspection...I could even slide it off its mount with finger pressure). The issue resolved when these parts were replaced. Hopefully this helps someone else with a similar problem.
2003 STR, 52K.