Watched M by Fritz Lang last night. Embarrassed to say that I'd never seen it before. It was Lang's first talkie, and in it he makes a character out of speech itself. The killer is introduced by newsprint, and referenced in various newspaper "extras," plots, proclamations, edicts and so on. We only know him through his whistle. We hear him speak only a handful of times. Until the end of the film, when he reveals his truth in a brilliant performance by Peter Lorre. The whole film seems to test the veracity and the authenticity of speech. Can we trust it to use it in films? Can not sound, like image, be manipulated for effect?
Silent films used intertitles to "narrate," this textual form of speech being third person, and indirect. Talkies introduce first person, direct speech. What's spoken is now spoken by an actor to another actor. What had been written in intertitles was written by the "film" to its audience (sometimes quoting what actors were saying to one another).
It does seem that Lang was aware of the possibilities as well as ambiguities of the Talkie, and that M is as much a study of speech and truth in media (film) as it is a detective thriller.