The Musical Score (also known as the Music Notes) is found on a shelf in the 1F west lounge of the Spencer Mansion.
The score is used to play the Moonlight Sonata on the piano in the bar. Jill Valentine will be able to play the piece by herself once she finds it, but Chris Redfield will only succeed with the help of Rebecca Chambers. Rebecca needs time to practice playing the song, prompting Chris to explore the rest of the mansion in the meantime (returning to the mansion's entrance is all that is required to trigger Rebecca to finish practicing). Once the piece is successfully played, a secret passage overlooking the Greenhouse opens that contains the Gold Emblem.
The remake expands upon puzzle by breaking the score into two parts. When examined, it's noted that the item has had its middle section torn out and is then referred to as the Missing Music. Until the missing section is restored, the item is unable to be used. Upon entering the small dining room later, the lighter can be used to light a candle on the table which allows the player to discover (moving the shelf) the remaining section of music in the secret room behind the moveable display cabinet. Once examined, the middle section of music is then renamed Music, mid-pages. When this item is combined with the beginning and last sections of music, the Moonlight Sonata is completed and can be used with the bar's piano.
In the original game, Rebecca plays three different attempts of the song (one ending with her slamming the keys in frustration) before finally learning the piece. Her trouble with the piano is referenced again in Resident Evil 0.
In the remake, the cover of the score actually reads, "Moon light Sonate".