Beck, Jay. “Citing the Sound.” Journal of Popular Film and Television Winter 2002.
    http://www.findarticles.com/p/articles/mi_m0412/is_4_29/ai_82779441/pg_4

The sound in The Conversation was nominated for Best Sound at the 1975 Academy Awards. While most of the sound production in the 1960s was remnant of the studio systems original sound technology, this film pushed sound production into a new era by exploring new ways to integrate sound into film. Since the central character’s job is to manipulate film, sound plays an important role. The soundtrack is a driving factor of the plot in its case, and it required the viewers to integrate their viewing experience with their listening experience. Films in the 1970s embraced “anti-realistic” tactics such as grainy film stock and lens flares, and this trend continued into sound in Coppola’s film. He used the sound to drive the narrative, which was a relatively new concept, only preceded by Antonioni’s film Blow Up. Influential sound producers defied the typical Hollywood hierarchy by running the production team democratically and allowing free experimentation in sound techniques. The problem with the technique of driving the movie with sound was that audiences were not used to integrating sound into a visual field. Harry not only provides a narrative for his films through the recorded conversation, he basically mixes the soundtrack throughout the film, acting as a sound mixer. A powerful aspect of the sound production is the “audio-zoom”, where the sound increases as the camera zooms into a crowd. The sound echoes what an eavesdropper would hear, it picks up on important conversations throughout the crowd. The sound relays Harry’s mental state to the viewer, and is heard from his perspective. The sound is not a redundancy of the actions on the screen; it is a complement to the action. The deconstruction of sound production in the 1970s was a result of the rebellion of directors to the studio system, but soon Dolby would standardize sound and mixing techniques and end the period of experimentation.