Vertov's The Man with the Movie Camera, stills
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montage theory

The radio ear:

Vertov had an interested in recorded sound and conducted experiments in realistic sound recording that paralleled his work in nonfiction film. The Man with the Movie Camera includes a section that seeks to present sound visually.

The film audience within the film watches sound waves on the screen. Ironically, this film was released in 1929, when sound was taking over cinema worldwide.
Man with the Movie Camera stills:
page 1 - page 2 - page 3
montage theory