A friend asked me to comment on a proposed curriculum for film school students regarding Post-Production audio. This made me refer to some old Walter Murch articles which still astonish me as to how accurately he describes the film sound experience. (Murch is the original holder of the title sound designer and has won several Academy Awards for sound editing, film editing and sound design.)
“This reassociation of image and sound is the fundamental pillar upon which the creative use of sound rests, and without which it would collapse…
film seems to be “all there” (it isn’t, but it seems to be), and thus the responsibility of filmmakers is to find ways within that completeness to refrain from achieving it. To that end, the metaphoric use of sound is one of the most fruitful, flexible and inexpensive means: by choosing carefully what to eliminate, and then adding back sounds that seem at first hearing to be somewhat at odds with the accompanying image, the filmmaker can open up a perceptual vacuum into which the mind of the audience must inevitably rush…
The rumbling and piercing metallic scream just before Michael Corleone kills Solozzo and McCluskey in a restaurant in “The Godfather” is not linked directly to anything seen on screen, and so the audience is made to wonder at least momentarily, if perhaps only subconsciously, “What is this?” The screech is from an elevated train rounding a sharp turn, so it is presumably coming from somewhere in the neighborhood (the scene takes place in the Bronx).
But precisely because it is so detached from the image, the metallic scream works as a clue to the state of Michael’s mind at the moment — the critical moment before he commits his first murder and his life turns an irrevocable corner. It is all the more effective because Michael’s face appears so calm and the sound is played so abnormally loud. This broadening tension between what we see and what we hear is brought to an abrupt end with the pistol shots that kill Solozzo and McCluskey: the distance between what we see and what we hear is suddenly collapsed at the moment that Michael’s destiny is fixed.”
This “sound-stretching” is the same thing composers do when working on a film. By stretching the distance between what is portrayed on screen and what is heard… the mind of the viewer perceives a vacuum into which they pour their own associations and emotion. The music is the sub-text to the screen action.