Compare and contrast the use of diegetic and non-diegetic music in film, explaining their respective functions and how they contribute to the overall narrative.

Diegetic and non-diegetic music are two distinct types of sound employed in film, each serving different narrative and emotional functions. The fundamental distinction lies in their source within the film's world: diegetic music originates from a source within the film’s story world, while non-diegetic music comes from outside that world, typically added in post-production. Understanding this difference is crucial for analyzing how music contributes to the narrative and emotional experience of a film.

Diegetic music, also known as source music, is music that the characters within the film can hear. It is part of the film’s fictional reality and can be heard by both the characters on-screen and the audience. The source of diegetic music can be visually seen on-screen, for example, a character playing a radio, a band performing live, or music playing in a club or concert. In other cases, the source may not be seen but is still implied to exist within the film's story world. Examples include the song playing from a car radio as the characters are driving or music from a party happening off-screen. Diegetic music can serve several purposes within a film. It can establish the setting, for example, the music at a specific period-themed club or the type of music playing in a coffee shop. It can provide characterization, for example, a rebellious character may play punk music, while a more cultured character may play classical music. It can be a tool for emotional expression by reflecting and influencing the characters’ states of mind, or it can be a part of the plot, where the lyrics and the music can enhance the narrative in different ways.

Diegetic music is also used to create realism, because these sounds are something characters would realistically encounter in their daily lives. Additionally, because the characters can hear the music, it creates an interaction between the characters and the music which makes the music an active component of the scene. For instance, in "Pulp Fiction," the use of diegetic music in the diner scene or the dance scene at the bar not only underscores the settings but also reflects the personalities of the characters and adds to the vibrant feel of the film. In "Almost Famous," the numerous uses of classic rock as source music create both a sense of period and a feeling of the lifestyle that the characters are a part of, directly tying music to their personalities and environment.

Non-diegetic music, conversely, is music that the characters in the film cannot hear; it is solely for the audience’s benefit. Often referred to as the film score or soundtrack, this music is added during post-production to enhance the narrative, evoke emotions, and create atmosphere. It is a separate layer added to the film’s audio, providing an emotional subtext that the characters do not experience themselves. Non-diegetic music can be used to foreshadow events, add tension, or amplify the emotional tone of a scene. It is more flexible than diegetic music, as it is not bound by the limitations of the story’s world. It can shift, evolve, and follow the emotional flow of the narrative without the need for a physical source. Composers use non-diegetic music to guide the audience’s feelings and reactions, manipulating tempo, harmony, and instrumentation to elicit specific emotional responses.

For example, in "The Lord of the Rings," the non-diegetic music powerfully enhances the epic scope of the story and underscores the emotional journey of the characters. The soaring melodies, heroic themes, and ominous underscoring are all designed to evoke specific emotions in the viewer and are not part of the Middle Earth narrative. The use of specific motifs related to characters and places allows the music to underscore the drama and enhance emotional impact. In "Jaws," the simple, repetitive theme for the shark builds tension and dread throughout the film, effectively setting the tone even before the shark is visually present. This kind of suspense-building, and mood-setting, is unique to non-diegetic music.

The contrasting functions of diegetic and non-diegetic music allow filmmakers to layer sound in complex and meaningful ways. Diegetic music provides a sense of realism, grounding the film in a believable world, while non-diegetic music adds an emotional and thematic depth that extends beyond the bounds of that world. Both types of music are valuable tools, and the way filmmakers combine and contrast them allows for a more nuanced and immersive cinematic experience. A film can also combine both in the same scene for instance, a song may start as diegetic, playing in a bar that the characters are in, then the non diegetic score may mix into the song and carry it to its conclusion.

In conclusion, while diegetic music is sourced within the film's world and contributes to realism and character development, non-diegetic music exists outside the story, serving to amplify emotions, enhance the narrative, and guide the viewer's experience. The interplay between these two types of music is fundamental to film scoring, each contributing to a richer and more complete cinematic narrative.