Some songs are sung by cover artists, and not the original artists, while others are sung by the original artists.
Songs
Songs have to be unlocked to progress through the levels and players can choose which one to play through the jukebox, which will then permanently be playing until the player change the song. You can start off with either, "You Are the Music in Me" or "You Are the Music in Me (Sharpay Version)".
The songs can be heard even if the Nintendo DS is closed.