Robert Bresson wrote, "the soundtrack invented silence." With the advent of dialogue, suddenly silence became scarce, and scarcity brought meaning. This video essay from Fandor Keyframe shows moments from 15 different films where "characters talk without [the audience] understanding or even hearing them." From comedy to tragedy, suspense to sadness, this video demonstrates the power of silence. 

Watching these clips should make anyone—especially a filmmaker—realize the truth behind the idiom (and I paraphrase) that the clever person always knows what to say, but only the wise one knows when to say it.

Sometimes, silence is an integral part of the plot, as in 2001: A Space Odyssey. This moment of murderous lip-reading by a supercomputer presents us with an image of great beauty while it also advances the plot and visually expresses the film's theme of human obsolescence; HAL 9000 understands language, but he doesn't needit. Throughout the film, almost none of the dialogue communicates anything beyond pleasantries and intentionally extraneous exposition.  

In this famous clip from the end of Lost in Translation, the mystery of the whisper (which some are eager to solve) is only a mystery because audiences are conditioned to look for secrets. By withholding what is said but showing the emotion in all its human ambiguity, Sofia Coppola subverts convention and turns what could have been a banal scene into a moment that people have been talking about for more than a decade. 

Source: Fandor