One thing that confuses me sometimes, is with the "play" action. Sometimes when I see it say "stop volume", I think of the when the audio is actually "stopped" (not playing at all), perhaps it could be renamed to "End volume" or "Final volume"? Also placing it after the "Start volume" would also help make it more logical!
(Also maybe the "fade-in" could say "fade-in time", just so it's even easier to read? Though this isn't as important.)
http://i.imgur.com/XqUkLE5.png
I think you did a good job with the ordering here though!