You're thinking of Pope Gregory, he's the one associated with Gregorian Chant:
Pope St. Gregory I ("the Great")
Doctor of the Church; born at Rome about 540; died 12 March 604. Gregory
Ah yes, thats right. I remember now, he was a Pope! Arg, my head is not big enough to hold 2000 years worth of stuff, and my 2 focuses are theology of the body and abortion/contraception apologetics, as well as Catholic practices apologetics (as a former baptist, these are thoroughly engrained in my psyche)
thanks for the clarification for me!