I noticed that when this procedure was done, students relax more and feel more comfortable during the test. I prepare a text, very imaginative, something that can take many different points of view, and read it out loud while the song's being played. Students have their eyes closed and I ask them to imagine exactly what I'm reading and let their imagination flows along with the song. If anyone needs some more suggestions, let me know. Simple, repetitive songs often contain a resurrent gramatical pattern.
More difficult songs contain interesting vocabulary and idioms.
Look for homophones, homographs and homonyms, as well as typical fast speech pronunciation. Look for conversation and writing topics. What a coincidence. I just did a similar thing with my student here in Japan recently. I was searching for a meaningful, fun lesson plan when I remembered she told me she wanted to learn English in order to understand American songs, movies, etc.