These are standard morae characters, so they have equal length in duration as other characters. But I can't really seem to get what is going on. Other similar characters like 'bya','pya' are really easy, but these three take on a new level. Moreover, its really hard to detect it in listening.
I learned how to pronounce my 'r''s. Now I need to know what is going on with these rya, ryo ryu