The Three Murmurs?
Relevant text in song:
". . .Three murmurs stood before my door, dressed in garments thin and poor. They prayed me by saint charity, to grant them kindly courtesy. I gave them bread, I gave them wine, for mary's sake, that maid divine. And who should be those murmurs three? But Joseph and his fair lady, and eke the christ child who entered in my humble door. . ."
Obviously the latter half answers my question in a literal sense, but why are they called murmurs, what is the context for them being called "murmurs"? Or am I wrong, and that murmurs refers to something else in this religion?