Here’s a word that no one uses unless they want to sound smarter than you: diegesis, that is the type of story that’s told by a narrator. Which means what, exactly? Well, in The Princess Bride the Grandfather is performing an act of diegesis when he tells the Grandson the story. The interactions he has with the Grandson are thus non-diegetic. Of course, it’s all a narrative being told to us, the audience, by the filmmakers in turn carrying out diegesis. In film criticism it gets a little more specific, referring to what happens in the film in and of itself.
Diegetic music is when music is played in the narrative itself. The band playing when Han and Obi Wan walk into the cantina in Star Wars is an example of diegetic music. The characters hear it, and so do we. As a bonus it adds texture to the world. It helps that it’s iconic enough that you’ve probably got it going in your head now.
It doesn’t have to be that big, though. (500) Days of Summer uses diegetic music as plot points; it’s Tom listening to The Smiths that helps strike up a conversation with Summer. No, it’s not a grand epic sequence (compare the Fairy Godmother singing “Holding Out For a Hero” during the climax of Shrek 2), but it serves the plot’s development and also provides an important touchstone of Tom and Summer’s relationship. We, the audience, are allowed to share in what brings Tom and Summer together. The film is not just telling us but showing us too, making the whole thing more immersive and more intimate.
And now I’m going to talk about Guardians of the Galaxy.
Diegetic music plays a huge role in Guardians, but not in the way it does in Star Wars. We’re not treated to a band playing local alien music as one would expect from a piece of fantastic science fiction. Instead, well, it’s pop music from the late ‘60s and early ‘70s. As in Earth’s ‘60s and ‘70s. And it makes perfect sense.
Peter Quill, the protagonist of the film, was taken from earth in ’88, his only belongings what he had in his backpack, the most important of which is a mixtape of songs his mom made him before she passed away. It’s very much Quill’s only physical and emotional tie to Earth as he gallivants around the galaxy under the name of Star-Lord. There’s a good reason for the parachronistic anatopism that is his music. Furthermore, the placement of some of these songs is often key. Hearing a prison guard manhandle his Walkman and listen to “Hooked One a Feeling” provokes him into a fight, for example. The songs are personal for Quill.
They can be personal for the audience too. Guardians of the Galaxy is outlandish on a Star Wars level, which is odd for any movie, let alone one that shares its world with Tony Stark and Steve Rogers. Having Star-Lord listen to “Come And Get Your Love” while exploring a ruin on Morag immediately clues the audience in that, yes, we’re still in the same world of the 1988-set prologue.Having the characters listen to it also gives us a connection to them. Look at the spectators stomping and chanting “We Will Rock You” during the opening joust of A Knight’s Tale. Like inGuardians, it gives the audience something in common with the characters. We’re all listening to the same music.
Diegetic music can be used to great effect. Film critics love to cite the infamous patricidal mambo from Douglas Sirk’s Written on the Wind as a prime example, but I’m gonna throw in Guardians of the Galaxy too. Diegetic music done right can do wonders to a film, be it through adding texture, granting intimacy to the audience, or serving as a character’s emotional touchstone. That and it’s pure fun to see Star Lord fly through space to “The Piña Colada Song.”
And yes, a lot of the music in The Sound of Music is diegetic, what with it being a musical and all.