Staying In Shape - The Human Touch in the Mixing of a Soundtrack

There is a lot of talk in the sound world about the ‘shape’ of a soundtrack. I’d like to examine and demystify this metaphor. Firstly, the word ‘shape’ is generally taken to mean the physical form of something. We often borrow these physical terms to describe sound: high, low, deep, piercing, soft. Often we use the shape of a waveform depicted on a graph: sinusoidal, square, sawtooth, flat, rounded, spiky, smooth.

To me this proves that we have developed such a lexicon in describing the invisible concept of ‘sound’ that we can understand a soundtrack as having shape. Just as a revered piece of music has shape (the oft-cited example is Beethoven’s 5th). The shape is provided by the contrasts of timbre, volume, harmony, harmonic timing; giving rise to contrasts between tension and release, expectation and subversion of it, predictability and convention vs the subversion of that.

Therefore, we tend to use words like ‘flat’ and ‘full’ and ‘dynamic’. Flat has metaphoric and practical understandings. A flat soundtrack is one that makes you feel just that. There is nothing unexpected or surprising. Interest wanes rapidly. It might be a perfectly technically acceptable mix, but too much has been made of making it fit into a mould; not too startling, safe. Boring. Naturally, for some shows this is exactly what is required. I like to watch physics or philosophy lectures. The last thing I want is the annoying whizz-bang of massive sound effects and music. When I see too much of that in the wrong video, I get suspicious. Is the content so uninteresting they have to try to distract me with all those bells and whistles? Conversely, if I’m watching an action drama, where movement and excitement is part of the storytelling, I need what we call a dynamic mix.

Dynamics are the technical term for the difference between volume levels (loud and quiet). The term broadens when we use it to describe intensity, because intensity is not just volume. It is a bit more of an elusive term, encompassing busy-ness vs simplicity, harshness vs smoothness of timbre, varying balance between the bassier and the more trebley frequency content. Even the choices of sonic material influence intensity. The term starts to stray into the more artistic than technical side of language, and as such becomes more nebulous and subjective. I would argue that an increase in intensity can only be discovered through a mutual exploration by the director and the sound team: there is no ‘intensity’ button. Hence, an AI algorithm would never be able to ‘dial up’ intensity by command, because by definition AI lacks the ability to engage in this exploration with the other artists. It can copy what has gone before, often very astutely, but it can’t collaboratively forge a new path.

‘Quirky’, for instance, is another term that pushes the understanding of how soundtracks might be described. The term is so subjective that it might be true that no two people agree on the meaning. I think of quirky as meaning somewhat unexpected, brow-furrowingly comical but loveable. Will automatons ever be able to dial in quirk?

Augoyard and Torgue have produced a book called Sonic Experience, containing a whole dictionary of new technical terms to describe sounds. Invaluable though this volume is, the one thing it will never be able to instruct on is human intuition. An agreement we come to together, through a shared experience. We can’t progamme it, but we ‘know it when we hear it’.

The shape of a soundtrack has an overall impact on how we react to it. We want to hear the human hand in it. It is often most satisfying when the ‘shape’ evolves from the start to the end.

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