There’s a long list of common words that are often mispronounced (“Arctic” not “Artic”; “athlete” not “athelete”; “cornet” not “coronet”). While every self respecting online dictionary includes audio pronunciation these days, here are eight more that are dedicated to teaching correct pronunciation with the help of audio.
http://www.makeuseof.com/tag/8-online-audio-pronunciation-guides-speak-words-correctly/