If one said, for example, "I will not hear evil" with the intention of not listening to offensive music, what has he forbidden himself from?

Can such a general statement go into effect?
If so, what if the statement was as general as, "I will not sin?"

Is it possible that it does not go into effect because his intention does not match the implication of his words -- that he will not hear any evil?

If it does go into effect, has he only forbidden himself from music as he intended, or has he also forbidden himself from things such as lashon hara as implied by his verbal statement?