by George Valsamis
Diphthongs (two sounds/letters united)
There are eleven pairs of letters, that we call diphthongs (δίφθογγοι = δύο φθόγγοι, two sounds). They sound like one letter. For the moment it suffices to know that generally diphthongs are long.
The main diphthongs are 8: αι, ει, οι, υι - αυ, ευ, ηυ, ου
There are also three improper diphthongs: ᾳ, ῃ, ῳ - the subscript line is the second vowel of the diphthongs and is an ι (called iota subscript)
Note how the diphthongs are pronounced:
αι is pronounced like a long ε
ει, οι and υι are pronounced like η
αυ is pronounced like αβ or αφ *
ευ is pronounced like εβ or εφ *
ηυ is pronounced like ηβ or ηφ *
ου is pronounced like 'oo' in the English 'too'
* By forcing air between the lower lip as it rests against the upper teeth (as in English).
When you see a diphthong with a diaeresis on the second vowel (like the German umlaut: αϊ, etc., you pronounce two distinct vowels.
Improper diphthongs sound like there was not a second vowel (the iota subscript):
ᾳ, sounds like α / ῃ like η / ῳ like ω
Note: When the first letter of the diphthong is accented (with a circumflex, grave or accute accent, independently of breathing marks) then the diphthong is read as two distinct letters, and diaeresis ( ¨ , diaeresis means "division") may or may not be written in the second letter. When the second letter is accented, or when none of the letters is accented, then, if the letters are to be read separately, diaeresis has to be written. E.g.:
- "Μωϋσῆς" - none accented, they are read separately, diaeresis is written.
- "ἔνδεια" - none accented, they are read as one vowel (a somehow longer i), diaeresis is not written.
- "βαρεῖα", or "πλείστοις" - second accented, they are read as a single vowel (a somehow longer i), no diaeresis of course.
- "ἄυλος" or "ἄϋλος" - first accented, they are read separately, diaeresis can be written or not.
- "ἀΰλῳ" - second accented, they are read separately, diaeresis has to be written.
Reference address : https://www.ellopos.net/elpenor/lessons/lesson1.asp?pg=7