We need to be very careful with the transcription of mr. Karakatsanis. He makes some important mistakes (ex. "τερκικότερον" in later spot, etc), I am sure, not in purpose (we owe him a lot for publishing these books).
Karakatsanis version: "Ἡ φωνὴ ἕως οὗ εὕροι ἄλλης φωνῆς ἶσον, ἤτοι μεταξὺ δύο περδέδων, τερκικώτερον γεννῶνται ἄλλαι δύο φωναὶ κατὰ τὴν διδασκαλίαν τοῦ κὺρ Μανούλ, πρώτον φωνῆς, δεύτερον φωνῆς καὶ τρίτον, εἰ καὶ ἐφθαρμέναι, ἤτοι φθορικαί."
He gives an awkward meaning in this word "τερκικώτερον" using the context of the entire sentence (he suggests these possible explanations: "μαλακότερον", "λεπτότερον", "τρυφερότερον" etc). But it is obvious that the original word is τουρκικώτερον as found in other mss (Karakatsanis sais that in the Preface) and is placed there to justify the term "περδέδων" which is a Turkish word (περδές, perde). It's exactly the equivalent of the phrase "επί το ελληνικότερον"