>>678
It is not pronounced EXACTLY like "I earn", but something very close to that. ("I earn" would be stressed in the second syllable: i EARN /aɪˈɚn/, while "iron" would be stressed in the first syllable: I-earn (= EYE-urn) /ˈaɪɚn/.)
Actually, EYE-urn would be a much better way to describe what it sounds like.