Guest,
There are many ways to go it seems to me. The academic route is one of them. Usually, there are two approaches. Monographic. Ethnographic. First is a study in-depth of a specific music and it's culture where measurements are taken and examples analyzed. Second, an overview of the world's music in the way that Lomax attempted. Whether his "cantrometrics" really works is not for us to say right now. Over time, we'll know.

Selective reading by Kremenliev, Meriam, Kurt Sachs, Charles Seeger (Pete's dad, an excellent ethnomusicologist)...A.L. Lloyd,Bela Bartok and Kodaly, Mantle Hood, and others in the field would give you some perspective.

I believe that much can be learned by independent study if you have a specific cultural orientation. I would trust what Joe Heaney, Mick Maloney or Willie Clancy had to say about Irish music.   I would trust what Jean Ritchie had to say about Appalachian music or Ewan McColl and Jeannie Robertson about the Scottish ballad. A lot has to do with what music you want to study.

Frank Hamilton