The Cause:
I suspect the cause to be the battle scenarios over Whiterun and the other cities in the civil war questline. These scenarios are scripted so that battle music plays without interruption for the entirety of the battle. Something about this script causes the game to go wonky, however. After the Battle of Solitude, when Ulfic gave his speech of my proud Nord, I could barely hear him over the still continuing battle music (this is a bug that I've been able to google many instances of). After leaving Solitude, however, this seems to be when combat music stopped playing for many encounters. Dragons are guaranteed to have working music, as do mammoths, giants, and city guards, but otherwise it seems whether music plays is entirely random. As I kept playing more and more of the audio bugs showed up, and it seems today it has only gotten worse with this new magic bug. I retracted the bug when I had the game installed, I had uninstalled it with no effect, and I've reinstalled it again. I've taken all the saves off my Xbox before, as well as deleting the updates. I know that there is other information carried with skyrim that I can delete using a cache wipe, but for some reason when pressing Y on the HDD and saying yes to the prompt, the window simply closes without going through the process.
I really want to enjoy this game, I simply can't believe I've put up with this for so long, it's no way to play.