nash

http://www.airwindows.com/analysis/Dynamics.html

That's an analysis of records with continued 'selling power' (e.g., Led Zeppelin, The Eagles, Fleetwood Mac, The Beatles) using sonograms. The author points out the differences between these platinum+ records and the music of today. I don't know much about audio mastering, but according to the author, there are some pretty easy to follow rules for almost-guaranteering a successful album. It's an interesting but long read.