Aspirated diptongs' pronounciation

[Swth\r]

In Greece, we read ancient Greek texts in terms of modern Greek pronounciation, as the alphabet is exactly the same in both languages.

So, my question is about aspirated dipthongs. What exactly was their pronounciation in classic attic dialect? Was the aspiration blown at the beginning of the dipthong or between, as the orthography indicates? E.g.:

οἷς -> [ho^is] or [o^his]

If I remember correctly in the pre-Eukleidian alphabet the spelling was ΗΟΙΣ... Is it correct? What Allen sais? I luck "Vox Graeca"...

[annis]

The aspiration is initial, as the earlier spelling ΗΟΙΣ indicates. It's just a convention of orthography that breathings and accent marks go on the second element of a diphthong.

The only word I can think of that has a written aspiration mid-word, between vowels is εἶἑν (the interjection, not the optative of εἰμί), but that's not really in a diphthong.

[Swth\r]

Χάριν σοι ἔχω, "annis".

Another issue came across my mind... Simple consonants become aspirated before aspirated vowels, and that indicates the presence of aspiration in compound words. Nevertheless, in compounds with certain prefixes the aspiration is kept out of orthography; but in pronounciation? E.g.:

κατά + ὁρῶ = καθ-ορῶ [kat-h-or^oo]
ἀπό + αἱρῶ = ἀφ-αιρῶ [ap-h-air^oo]

but:

πρό +ὁρῶ = προορῶ; was it said [pro-h-or^oo] or [pro-or^oo], as the spelling shows? The same with:

ἀνά + αἱρῶ = ἀναιρῶ; [an-air^oo] or [an-h-air^oo] or perhaps what else...?
πρός + ἕξω = προσέξω; [pros-e/xoo] or [pros-h-e/xoo] or what...?

Thanks!

[annis]

Nevertheless, in compounds with certain prefixes the aspiration is kept out of orthography; but in pronounciation?

This is a gap in the orthography. I pronounce the aspiration in compounds, even if it isn't written. Not only is it consistent with the behavior of καθ-ορῶ, but from time to time we get Latin records of certain words in which they do write the aspiration. For some reason the example I always think of for this is Εὐήμερος, Euhemerus.

[Swth\r]

This is what I suspected. Thanks!

[modus.irrealis]

I'm always reminded of the Hebrew word sanhedrin which comes from συνέδριον, which suggests that at least some people preserved the aspiration in such compounds even in post-classical times.