for instance, ai au. Two are suffixable: i and y. And y is sometimes prefixable before i, as in myia and harpyia. Six are diphthongs: ai au ei eu oi ou. The remaining seventeen letters are consonants [pronounced-with]: b, g, d, z, th, k, l, m, n, x, p, r, s, t, ph, kh, ps. They are called consonants because they do not have a sound on their own, but they form a complete sound when arranged with vowels. Of these, eight are semivowels: z, x, ps, l, m, n, r, s. They are called semivowels, because, though a little weaker than the vowels, they still sound pleasant in hummings and hissings. Nine are mutes: b, g, d, k, p, t, th, ph, kh. They are called mute, because, more than the others, they sound bad, just as we call a performer of tragedy who sounds bad voiceless. Three of these are thin (k, p, t), three are thick (th, ph, kh), and three of them are middle [intermediate] (b, g, d). They are called middle, because they are thicker than the thin [mutes], but thinner than the thick [mutes]. And b is [the mute] between p and ph, g between k and kh, and d between th and t. The thick [mutes] alternate with the thin ones, ph with p, as in [an example from the Odyssey]; kh with k: [another example from the Odyssey]; th with t: [an example from the Iliad]. In addition, three consonants are double: z, x, ps. They are called double because each one of them is made up of two consonants: z from s and d, x from k and s, and ps from p and s. There are four unchangeable [consonants]: l, m, n, r. They are called unchangeable because they do not change in the future [tense]s of verbs and in the declensions of nouns. They are also called liquids. External links University of California, Berkeley: Practice of Ancient Greek pronunciation Society for the oral reading of Greek and Latin Literature: Recitation of classics books Desiderius Erasmus, De recta Latini Graecique sermonis pronuntiatione dialogus (alternative link) Brian Joseph, Ancient Greek, Modern Greek Harry Foundalis, Greek Alphabet and pronunciation Carl W. Conrad, A Compendium of Ancient Greek Phonology: about phonology strictly speaking, and not phonetics Randall Buth, Ἡ κοινὴ προφορά: Notes on the Pronunciation System of Phonemic Koine Greek Chrys C. Caragounis,