Some examples of non diegetic music

And here are some more examples of non diegetic music in films. 

The shower scene in Psycho, directed by Alfred Hitchcock in 1960, is one of the most famous in scary movies. You can see the difference between the use of music here as opposed to the use of diegetic music that we saw in the previous examples: here the characters cannot hear the music, the source is not part of the story (we can't see anyone singing or playing an instrument or putting on a record): it does not form part of the world they are living in. But for us viewers, it is fantastic! The use of repeated very high notes makes it very scary!

Movieclips. The shower scene in Psycho. Licencia YouTube

I bet you've seen Jurassic Park. In this scene we hear John Williams' music but the characters and creatures certainly don't! There is no orchestra there! The use of the non diegetic music here inspires awe and amazement on this first occasion when we see the dinosaurs.

BestClips. Jurassic Park. Licencia YouTube

There is powerful use of non diegetic music in the opening scene of the 1988 film Mississippi Burning about racial hatred against the African American community in the United States. The image shows a house burning down (after being presumably set on fire by the American white supremacist hate group Ku Klux Klan), while we hear the beautiful negro spiritual "Precious Lord, take my hand". We therefore know this is going to be a moving, socially committed film. 

Jennifer Corleone Wu. Mississippi Burning. Licencia YouTube

The James Bond films have always used music well and the series has a famous theme tune. In this clip from Moonraker, in which Bond (a spy also famously known as 007) and the "baddie" Jaws are skydiving, we first of all hear the theme tune which of course adds excitement to the scene, and then there is a dramatic change in the use of the non diegetic music when a circus tune is heard, reflecting the comic end of the action. 

Ronald Brown. James Bond. Licencia YouTube