First off, I can't read stuff written in Greek, and second, I am lousy at reading medieval Greek mss copies of patristic works, even those freely available in digitized form. So I don't know anything more than what this article says.

In the newly discovered (or newly re-catalogued last June) copy of Origen's homilies on the Psalms, Perrone notes that Origen mentions several things about music in his "Second Homily on Psalm 67." (Ps. 67:5/68:4 is quoted.) He talks about the distinction between unaccompanied and accompanied singing, but also uses a hapax legomenon (a word known from only one use in the whole of Greek lit) for vocal training. (I think the word transcribes as "phonaleptike," which he defines as a "tekne phonaskike.") He apparently also refers to both musical theory and performance concepts.

This is on page 13 of this article:
on page 13 of Perrone's description paper.

The homily with the word on it is on folio 99v of the mss, according to the article's footnotes. (That's the back (verso) of page 99; on the digitized version it's Bildnr. 204.) I don't know if it's one of the homilies previously translated by Rufinus or Jerome.

Here's the digitized page if you want to play the home game.