On The Magic Nook Forum in the Mentalist's secret section, there is a description of a Christmas effect, that could easily be adapted for an any-time-of-year-musical-effect.
I originally designed this for use at an adult party in a room with a large Christmas Tree. I offered a spectator a choice of several Christmas music books, had them leaf through the book to locate the title of any Christmas Carol they could sing, and while the audience sang or hummed the carol in the background, I led the spectator to the tree and pointed out a clear glass ornament that was hanging high up on the tree. I gave her a hand getting up on a little portable step ladder so she could remove the ornament. Inside the clear glass ornament was a piece of paper with appropriate Christmas colors and decorations on the outside and on the inside was my prediction, but personalized to the spectator: "Susan will choose Joy to the World."
Any popular music books could be used, and instead of locating the prediction in a glass Christmas tree ornament, it could be found anywhere at all.
Using a programmable digital voice recorder, you could even have a person select a song from the book, and then hand them the recorder to press the button and the song immediately begins playing, but only the accompaniment- you get to fill in by singing the chosen song yourself. Keep that talent of yours in the forefront. It makes your act unique.