User blog comment:Deathstalker666/The Sound of Shotguns/@comment-1496755-20170308215935/@comment-1496755-20170309193311

It's an inherited thing - E12N took 4 (I think) maps from an entire episode designed by someone else and the music/sounds came with them. For some reason, though, E1M7 and M8 don't have custom music... but the tally screen does (sounds a little like Superman's theme).