Production Sound Mixer

What they do

Reads the script for sound problems before anyone books a location: the scene in the rain, the two-hander beside a motorway, the crowd. Walks recces and listens for HVAC, refrigeration, generators and flight paths, then asks locations and electric to deal with them while there is still time. Specs and supplies the kit: a multitrack field recorder such as a Sound Devices Scorpio or an Aaton Cantar, a fader control surface, wireless from Lectrosonics, Wisycom or Zaxcom, boom mics, lavaliers, IFB headsets, timecode boxes, RF distribution and remote antennas. Books and coordinates radio frequencies, runs a scan at each new location and checks for intermodulation. Hires the boom operator and utility. On the day they route an isolated track for every microphone plus safety tracks, record a mix on top of them, ride faders through the take, and ask the first AD for another one when a plane goes over. They feed IFB to the director, script supervisor and video village, and record wild tracks and room tone. Files are named to match the slate and the continuity log, and the sound report the dialogue editor will navigate rushes with carries scene, take, file, track layout, timecode, sample rate, bit depth and roll. Audio rushes go to the DIT daily, with a personal backup kept as well.

What they decide

The calls that belong to this role and no other.

• Which microphone covers each line, and whether it is carried by boom, radio mic or plant mic
• The track layout: what lands on each isolated track and what the mix track contains
• Whether to ask for another take for sound, though the director decides whether to grant it
• Which radio frequencies the production uses and how the RF is coordinated across departments
• What the sound package is, what is rented and what the mixer supplies
• How files are named and what goes in the sound report

Principles of the craft

• Clean beats loud: noise you record cannot be un-recorded. A slightly quiet, clean line survives the dialogue edit; a hot line with a fridge behind it does not. Level is adjustable later, separation and noise floor are not.
• The isolated tracks are the deliverable, the mix is a courtesy: post rebuilds from the ISOs, and the mix exists so dailies and video village make sense. Design the track layout for a dialogue editor you will never meet.
• Sound problems are cheapest before the camera rolls: HVAC switched off, generator moved behind a building, a prop softened with moleskin, a lockup on foot traffic. 'Fix it in post' means paying an actor to re-perform the line in ADR.
• Pattern follows the room, not the format: a shotgun's interference tube rejects the outdoors, but in a small reverberant room it introduces phasing and comb filtering, where a supercardioid sits better. Choose for the acoustics in front of you.
• Room tone is a deliverable: half a minute of the actual noise floor lets the dialogue editor bridge edits and gives a de-noiser a profile to work from. It costs a minute on the day and saves a session in post.

Common mistakes

• Chasing level instead of separation, so transients clip and a shouted line has no headroom left
• Recording only a mix, or putting two actors on one track, leaving post no way to separate them
• Wiring everybody and abandoning the boom, then delivering thin dialogue full of clothing rustle
• Skipping room tone and wild tracks because the day overran
• File and roll naming that does not match the slate or the continuity log, which costs the assistant editor hours
• The competent mixer's mistake: quietly absorbing every problem and never telling the director a take is unusable, so it surfaces months later as an ADR line

How to learn it

Exercises and routes in, not a reading list.

• Record the same 60-second dialogue scene four ways in one room: shotgun from above, shotgun from below, supercardioid from above, and a lavalier under a cotton shirt. Same performance, same gain. Listen on headphones and describe the room in each. Then repeat outdoors and note which choice flips.
• Record a scene with an air-conditioning unit running, then again with it off, then try to de-noise the first to match the second. Note what the process does to sibilance and to the actor's breath.
• Set a recorder to capture isolated tracks plus a mix, then hand only the mix to a friend and ask them to make one actor quieter. Watch it fail, and you will never deliver mix-only again.
• Write a full sound report for a day you actually shot: scene, take, file name, track layout, timecode, sample rate, bit depth, roll. Give it to whoever is cutting and ask them what was missing.
• Sit at video village on someone else's shoot with headphones on the mixer's feed and write down every noise you hear that will be a problem. Compare your list with the mixer's afterwards.