Listening and Memorizing

I’ve been working hard to learn all the words to three songs. Over and over and over. Amazingly enough, I’m not sick of them… yet.
Been trying to keep an eye out for an easy book on CD (so I can listen to it at work and in the car) because I don’t have time to sit down with a book and follow the words. So it has to be something where I know some of the words and can practice figuring out the rest, like pieces of a puzzle.
The thing is… I’m memorizing these songs and recognizing the words based on music cues. How is that going to help me hear unfamiliar words? I can’t make out the lines I don’t know from a song period.