The height of the vault, the solid stone of the pillars and walls, took up the sound of Brother Anselm’s voice, and made of it a disembodied magic, high in the air.
Take this effect and make it into an actual magic effect in a dungeon. In a vaulting chamber, a disembodied male voice is singing in an unknown language. What could be causing this effect?
It could be that the chamber is the crypt of a holy paladin. The voice is that of an angel, sent by a god to mourn at the paladin’s tomb for 1000 years.
Or it could be the ringing of a magical bell that tolls with a human tongue. If the PCs investigate, they will find that the song of the bell can be imbued in their weapons and implements. The weapons will sing in harmony until the song fades in 5 minutes. During this time, all attacks do extra sonic damage.
The fact that it’s a male voice is, I think, important towards keeping the PCs investigating with an open mind. There are so many female “gotcha” monsters in D&D that any woman, or woman’s voice, encountered in the dungeon will make PCs certain that they’re about to be charmed, or petrified, or bodyswapped, or vargouilled, or bansheed, or consumed by spiders, or something.