vowels
From LSJ
ὁποία δ' ἦν αὕτη ἡ παίδευσις δύναταί τις γιγνώσκειν διάλογόν τινα τοῦ Πλάτωνος σκοπῶν → It's possible to find out what kind of education that was by examining one of Plato's dialogues
P. τὰ φωνηέντα (Plato), V. φωνοῦντα, τά (Euripides, Fragment).