"En gutt" can be any random boy, but when saying "gutten" you are talking about a specific boy.
OK, so why two different constructions? Are they interchangeable in any sentence, or are there times when one is proper and the other not? (Takk!)
In Norwegian you put the definite article after the noun, not in front like in English, Spanish and French. The definite article here is "-en" which is placed after "gutt", but with neuter nouns it would be "-et". With feminine nouns it would be "-a". Sometimes, when there is an adjective before the noun, you will put "den" or "det" in front of the adjective as well.
Just i hear it, or the voice really said "guttn" ? Is it the correct prononcuation?
You can say both, but it will often be pronounced differently depending on where in Norway you are.