What's correct? Well, as far as English is concerned, it used to be the King's English (that is, the English spoken by the king of England on the odd occasion when one of them happened to speak English as his native language) but now people quite happily claim American and Australian pronunciations as examples of orthoepy, and there are plenty of passionate advocates for the legitimacy of a thousand other dialects.
Basically the whole idea of orthoepy has gone right out of fashion.
Amusingly, though, people are still arguing about the orthoepy of the word orthoepy.
Which just goes to show how ridiculous the whole idea was to start with.
Word To Say Correctly Today (ha!): orthoepy. This word comes from the Greek ortho- straight and epos word. You can say the word ORthohEEpee, ORthohEPPee, ORthohIPPi, ORthohUHpee...or however you like, really. I would probably stick with four syllables, though.