By description, mixing sound is very simple: It’s manipulating the balance of one sound to another in a way that’s aesthetically pleasing (moving knobs and buttons, basically). Over the years, I’ve come to see it as more than that. It’s still as simple, but a different philosophy.
I see mixing (of all types) as telling a story. It’s still deciding how the sounds need to balance one another but for the purpose of sharing a story. Sometimes there’s words to that story and sometimes there’s not. But, it’s asking at any given moment what the most important sound element is (or isn’t) and weaving a story together. Hans Zimmer used a great analogy in his Masterclass course: He’s like a chef who’s picking ingredients and putting them together in a pot for the guests coming for a party. Depending how it’s prepared, different flavors or ingredients could be featured.
A simple analogy is watching a movie where different characters are on-screen having a conversation. With dialog, it is usually easy to tell who should be featured in a given moment – it’s the person speaking, or who’s dialog is most important to understanding the story. But, mixing dialog in a scene is a bit like watching soccer and trying to follow the person with the ball, but at the some time seeing the big picture, and trying to anticipate what could happen next.
In musical theater, the style of mixing used is called “line by line mixing” where they literally drop (or mute) and raise mics based on who is speaking in any given moment. In post-production for film or tv, we often don’t work that dramatically (especially if there is natural room tone/background noise that would be noticeable quickly rising and falling). We do tend to remove (or mute) mics of people who aren’t talking, especially for long periods of time.
In an orchestra recording, the story could told by one person, like a soloist who is in the forefront of the mix for most of the performance. Or, in a symphony, those lead lines rotate through players just like lines of dialog alternate between characters in conversation. An important musical line could start with the violin and move to the oboe then to the trumpet. In classical music recording (and mixing), the approach is often naturalistic, letting the performers balance between themselves (like asking the cellos to play quieter so a melody line could be heard). In film scoring (which can have the same instrumentation), the approach tends to be more hands-on – having a mic on every section or unique player, and sometimes making these balance adjustments through microphones in a mix.
No matter what is being mixed, it’s a matter of defining who should be telling the story at any given moment, and asking, “What do I need to do to support that?”
When mixing trailers, promos and advertising/marketing pieces, we might be telling a 30 minute story in 30 seconds (or a 2 hour story in 2 minutes). The picture edit will often dictate what element of sound should be telling the story at any moment. Sound FX are used to draw attention to important picture moments or to help create shifts in the story or the mood. There will be moments where music and sound fx drive the story (think of a trailer for a big action movie), and other times when the dialog leads the story (this is often the case with comedy trailers/spots).
As a mixer, you learn this by practice, and also by analyzing the work of others. In a television show, when is the music loud and telling the story? What is going on around it – is there still dialog, and if so, is it a montage or emotional moment? What are the characters doing and what emotions might they be feeling?
Occasionally you’ll look at a spot or a scene and be stuck what the story is meant to be. In those cases it can help to ask the editor, producer or director to walk through it. What are the characters feeling or what’s happening in this scene? Is the viewer supposed to be present and focused on the characters’ dialog, or is there something more going on? Is there missing music or sound design that is supposed to be telling the story in this moment? It could be a missing visual effect or explosion that’s supposed to tell the story, or a character could be hearing voices in their head but those voices haven’t been designed yet. It’s impossible for a mixer (or editor or sound designer) to know how to tell the story in these moments without the input of the person with the creative vision for it.
With a music score or a song mix, it may take talking to the artist or composer to find out what their intentions are. Sometimes in film scores you’ll get lots of simultaneous musical ideas – melodies and countermelodies, melody and rhythm, etc. Are solo lines supposed to be featured (telling the story) or just a texture within? Sometimes who is supposed to tell the story is not completely obvious. I worked on a project about horses and it didn’t even cross my mind til talking to the director that the rhythmic parts were more important than the melodies (to imitate the movement/momentum of horses). That completely changed the storytelling within the mix. Sometimes things like that we (as mixers) would never know unless we ask – or until we do a mix and it’s brought up as a mix note after the fact.
If you think if mixing as telling a story, it makes it easier to not take feedback personally. It’s not about you making mistakes or doing something a client didn’t like – it’s about enabling someone to tell the story they want to tell. Sometimes this story is obvious – like a documentary filmmaker or podcaster using sound to literally tell a story. In music, it can seem more subtle, but even a rock song or a country song is about moments of communication between players (similar to alternating jazz solos). The mixer’s job is to help find those moments and bring them out tell the story.