Interesting.
If all the floors are made with enchantment spells and Vim cam enchant other people with permission...
What if there's a Dungeon Master of a god of sorts running the dungeons and by messing with his brain thanks to puppet master, Vim is slowly tuning in to the same frequency as the being thay cast the enchantments on the dungeon, hence the weird voice only je is able to hear?
Or if you wanna be more cliche, maybe Vim is a piece of the being controlling the dungeon or the guy/god that made the dungeon so he's hearing echoes of his own magic?