If English is not your native language you might have encountered some words that you did not know how to pronounce correctly. How would you pronounce zealously or eligibility for instance if you never heard the words before ? Even in the English language family words are pronounced differently depending on the region of the speaker. A Scott pronounces word different than someone from San Francisco.
If you want to get a impression how a speaker from the United States would pronounce a word you should visit the How J Say website. The site has a list of over 50000 English words and phrases that have been recorded and can be listened to right on the website. You can either type in a word that you want pronounced or browse the complete list of words and phrases available.