Hear Dziga Vertov’s Revolutionary Experiments in Sound: From His Radio Broadcasts to His First Sound Film
In that website there is a Dziga Vertov´s film Enthusiasm - very first experimental sound film. It is a propaganda, but very creative one. I recommend not so often heard radio experiments, you can find them under the film.
Click http://www.openculture.com/2015/04/hear-dziga-vertovs-revolutionary-experiments-in-sound.html link to open resource.