oe & eo

This is all IPA(International Phonetic Alphabet) vowel sounds.

There are three properties for determine the vowel in international phonetic classification:

-HEIGHT means height of rise top of tongue on the mouth.

We can determine six types of vowels due to this property: close, near-close, mid, open-mid, near-open, open.

Compare this sounds:

English vowel sounds:

Russian vowel sound:

http://dmiter.blogspot.com/2012/06/russian-language-lesson-vowels-vowel.html

上面是所有的语言的发音集合   oe 和 eo只是其中的子集。具体发音参考

eo

https://en.wikipedia.org/wiki/Close-mid_central_rounded_vowel

oe

https://en.wikipedia.org/wiki/Open-mid_front_rounded_vowel