When does a film not need music? Sometimes, the lack of music explicitly helps the story.The Office’s pretend-documentary format is more convincing without music. And the humor depends on rapid dialogue punctuated by awkward pauses. Music fits concept and style.
No Country for Old Men is practically without music (very light music creeps in only occasionally). Anton is evil and remorseless. He doesn’t feel anything, so why would we need music to underscore his feelings? Meanwhile, the Sheriff is so humble he thinks his dreams are boring to hear about. He’d be embarrassed to have an orchestra soundtrack his emotions.
Here’s one example – “Bleach” is a short film by Brand Tangonen which won a peer review award on filmmaka.com. We talked about possibly adding music on his story, but he decided against it.
You could argue that the flashback scene could have used some dreamy guitar, or some punk rock on the credits.
But the lack of music supports the story. It complements the scene’s dry humor. And the hero is clearly holding a grudge and doesn’t want to talk about it. We look at him differently if there is no music in his memory.