Multiple realities(covers information from several alternate timelines)
Sheet music was a paper document containing musical notes. By reading the notes, one could play the piece.
In 2372, Harry Kim played "Jazz Impromptu" on his clarinet with the aid of a piece of sheet music. (VOY: "The Thaw")
Harry Kim also had sheet music on display in his San Francisco appartment, in an alternate timeline inadvertently created by the officer in the same year. (VOY: "Non Sequitur")