Ok, after doing some experimentation, I had set my mp3s to be
spec1 = "mp3/05 - MOTOR HEAD -Tager-.mp3"; //Hell's Arena <-- each of these labels was based off of the assumption that this is the order that you would normally experience each special level
spec2 = "mp3/11 - Marionette Purple -Carl-.mp3"; //Chained Court
spec3 = "mp3/14 - Imperial Code -Jin vs Noel-.mp3"; //The Wall
spec4 = "mp3/04 - Bullet Dance -Noel-.mp3"; //Hell's Armory
spec5 = "mp3/21 - Blood Pain -Mirror-.mp3"; //Halls of Carnage
spec6 = "mp3/13 - Under Heaven Destruction -Ragna vs Jin-.mp3"; //Unholy Cathedral
spec7 = "mp3/06 - Catus Carnival -Taokaka-.mp3"; //The City of Skulls
spec8 = "mp3/05_riches_in_me.mp3"; //The Vaults
spec9 = "mp3/08 - Thin RED Line -Arakune-.mp3"; //The Spider's Lair
spec10 = "mp3/18 - Open The Gate -V13 Appears-.mp3"; //The Lava Pits
spec11 = "mp3/15 - White Requiem -Ragna vs Rachel-.mp3"; //The Mortuary
However, what happened was far, far different.
Since I was doing a Berserker Game (as Ragna The Bloodedge, hurr.), I made my first stop at the Chained Court, expecting to hear Marionette Purple. However, I heard Motor Head, which is labelled as Spec1 (Hell's Arena) instead of Marionette. I thought it was weird, but figured maybe spec1 was Chained Court and spec2 was Hell's Arena. I continued as normal anywayand made it down to floor 10, where I went to Hell's Armory to pick up the 4 blue armors. This time, Bullet Dance played (spec4, which I predicted correctly)
To test my theory about chained court and hell's arena, I decided to do a quick run to Hell's Arena as fast as possible, and when I got there, Bullet Dance played again, which makes no sense following my current logic.
So how exactly do the spec#s work?
EDIT: Worse yet, I went back to Hell's Armory, and this time it played Imperial Code! Does DoomRL just pick spec map BGMs at random?