Calliope was a Greek goddess, I think. (Pardon me for not looking it up.) It’s also a musical instrument. I’ve always heard it pronounced “ca-LI-o-pee”. But there is a Calliope St. in New Orleans and the locals pronounce it “CALLY-ope”. Why is that?
(There’s also a street called Burgundy that they pronounce “bur-GUN-dee”. I assume the accent on the second syllable is from the French influence; but in that case, wouldn’t it be “bur-gun-DEE”?.)
Probably the namer of the instrument was influenced by the literal translation of the name of the Greek muse: “Calliope” means “beautiful voice.” That the the instrument does not in fact have a beautiful voice is immaterial.
The pronounciation depends on where it’s located. The location of the calliope determined the pronounciation. A land based one, or a river boat one, each had a different pronounciation. I have to research, because I can’t remember which was which, and I don’t want to WAG.