Ancient Greek phonology East or West Greek dialects. They both raised Proto-Greek long to (see below). Later on, Attic lowered found immediately after back to , differentiating itself from Ionic. All other East and West Greek dialects retain original . Ionic was spoken around the Aegean Sea, including in Ionia, a region of Anatolia south of Aeolis, for which it was named. Ionic contracts vowels less often than Attic (see below). Attic is the standard dialect taught in modern introductory courses in Ancient Greek, and the one that has the most literature written in it. It was spoken in Athens and Attica, the
Ancient Greek phonology and this cluster underwent metathesis early in the Ancient Greek period. Metathesis is likely in this case; clusters of a voiced stop and , like , do not occur in Ancient Greek, since they change to by assimilation (see below), while clusters with the opposite order, like , pronounced , do occur. Ancient grammarians, such as Aristotle in his "Poetics" and Dionysius Thrax in his Art of Grammar, categorized letters () according to what speech sounds ( 'elements') they represented. They called the letters for vowels ('pronounceable', singular ); the letters for the nasals, liquids, and , and the letters