It is very helpful knowing these details. I should have spent more time digging out similar facts with English pronunciation. I am feeling Lucky to have friends like you here on the forum whose diligence made it up a little for me.
Your research reminded me of the idiom "learn by ear". I am the one who have been learning purely by ear -- a very inefficient way.
After reaching the current stage, I started to understand the reason behind the "exagerated mimicking" you did last year.