An often overlooked aspect of film adaptation is the inclusion of sound and music. In a literary text, a specific sound effect can often be implied or specified by an event, but in the process of adaptation, filmmakers must determine specific the sound characteristics that subliminally affects narrative interpretation. In some cases of adaptation, music may have been specified in the original material (usually diegetic music). In Stephenie Meyer's 2005 "Twilight" novel, the characters Edward Cullen and Bella Swan both listen to Debussy's "Clair de lune" and Edward composes the piece "Bella's Lullaby" for Bella. While "Clair de lune" was a pre-existing piece of music, "Bella's Lullaby" was not and required original music to be composed for the 2008 movie adaptation.