Music is one of the elements of a film’s sound design. It is different from dialogue and sound effects in that usually it does not have its source as part of the filmic space. Gunshots and door slamming, for instance, are heard when they happen on the screen (diegetic sound).
When Should You Not Use Music?
Too much music can be overwhelming. Sometimes it is preferred to let the audience hear the dietetic noises and sounds of the film world. In the documentary The Cutting Edge – The Magic of Movie Editing, it is discussed how music implemented over a specific scene of Dante’s Peak made the scene less effective because the music disguised the eerie sound of settling dirt in a mine shaft about to collapse. In this scene, music was a distraction that minimized the audience’s reaction.
Remember: as a filmmaker, your goal is to immerse the audience in your film. Music usually does just that. But if the sounds of the film world can achieve a similar effect, then you should ask yourself if you need music at all. As a general rule, you should never replace a visceral sound, like a woman screaming or a building exploding, with music. Maybe you can use music to augment the emotional beat, yes, but don’t let it overwhelm your sound.
And then there’s contrapuntal music, which goes to other extreme, countering exciting, sometimes even explosive scenes with mellow music.