Alvin, Simon and Theodore are taking voice lessons from Prof. Pitch before their big concert.; Dave and the Chipmunks try to get disc jockey Hy Platter to play their new record.; Annoyed when Alvin's early morning harmonica playing wakes him up, Simon throws the harmonica into an old haunted house.; Dave gets the Chipmunks jobs singing "Happy Birthday" to various people; but the trio manage to ruin the birthday parties they're hired for.; Alvin is sentenced to "clean up the town" when he is arrested for littering.; Dave gets the Chipmunks a job in the concert hall, but it isn't the one they had in mind.; Alvin wants to stay home from school to practice his harmonica, but Simon has a plan that gets him to school anyway.; The Chipmunks take several records into the listening booth at a record store, but stack them like playing cards rather than listen to them.