About Production Sound

Mixing console

Soundcraft 8 Channel Mixer

Introduction to Production Sound

My students receive an introduction to the technology and tools of contemporary sound recording for motion pictures. The emphasis is on how good Production Sound supports and enhances the Director’s vision. Students will be able to apply this knowledge to the sound requirements of student or independent film work.

In my lectures, labs and guilds students learn about:

  • How the Sound Department integrates and interfaces with all other departments including post production. While not discussing the details of post production audio, I do present an overview of everything that comes up on the set in relation to Sound.

  • The best and most practical ways to capture production audio.

  • The realities of production today and how these affect the Sound department – the value of passion and a strong work ethic, including bringing you’re A game to work.

  • Supporting the story telling process via recording performances

  • Supporting the script with audio

  • Introduction to most of the equipment used in production sound including

1. the set up of 744T recorder
2. demonstrate use of wireless and plant mics
3. how equipment interfaces with electric department and camera

  • Basic Boom Operation

1.Dynamics of production from booming perspective including capturing performance – perfect mic placement
2. Understanding lenses
3. Understanding actor’s perspective; relating to actors
4. Perspective audio; listening
5. The finesse of boom operation – dancing with the actors, camera, and lights are all things which we experience and work on while working on a set sound department.

  • Utility Sound work –

1. all students learn how to wrap cable and
2. cable placement
3.cabling safety
4.Other duties

  • Set safety.

  • The creation of sound reports.

  • Meta Data basics – sound formats and the delivery of audio formats.

  • Time code basics in reference to during production.

Production Sound Mixer Set Up

Sound Equipment set up on two carts on a sound stage

In addition students learn valuable skills that will help them in their quest to be working filmmakers:

  • Learning to listen – students will learn how to listen through headphones, and to recorded sound and to notice and evaluate quality.

  • Teamwork – students will learn how to work effectively as part of a team, close to the camera. Your will come to understand the dynamics of the set.

  • Set Etiquette – Working or waiting quietly, focusing on the dialogue and performance.

  • Knowing what the camera is seeing.


On the Set at LAFS

On Set at Los Angeles Film School. Photo Credit: Paul Torres

Sound department overview

 Sound department work is exciting, extremely important, and very rewarding. We work closely around the camera with every department and are central to production.

*Sound Mixer – The sound mixer is the head of the department and is in charge recording the dialogue and recording consistent levels and the smooth operation of the department. Ultimately the mixer is responsible for the quality of the work produced by the department.

The mixer’s work can only be as good as his boom operator’s work.

*Boom Operator – Boom Operators are responsible for placing the microphone in the best position, without impeding camera operation, or hampering actors’ freedom to perform. Clear dialogue is expected by cinema audiences, and this is usually achieved by placing microphones suitably close to the actors saying their lines. This is part of the Boom Operator’s responsibility, and is a physically difficult enterprise. Boom work requires a great deal of skill and experience, which you will gain while working in the sound department of the Production One set.

*Cable Wrangler/Utility Person – This person is responsible for keeping the cables in order and maintaining signal flow to the camera and the sound cart, as well as handling cables during moving dolly shots. The cable person works the shot every time the dolly moves while shooting. He or she is responsible for department paperwork, repairs, making sure that rental gear is where it needs to be when it needs to be there. The Utility also acts as a second Boom operator when necessary.

XLR Cables

XLR Cables properly wrapped

The Physics of Sound

The two components of sound are frequency and loudness.

Frequency is:

  • the number of occurrences of a repeating event per unit of time.

  • the tone of a sung or played note on a musical instrument -a key on a Piano or the strike of a Tuning fork.

A Wave is a disturbance that travels through space and time, usually accompanied by the transfer of energy.

The period is the duration of one cycle in a repeating event (wave), so the period is the reciprocal of the frequency.

Loudness as perceived by the human ear

Loudness, a subjective measure, is often confused with objective measures of sound strength such as sound pressure, sound pressure level (in decibels), or sound intensity or sound power. Filters attempt to adjust sound measurements to correspond to loudness as perceived by the typical human. However, loudness perception is a much more complex process.


A harmonic of a wave is a component frequency of the signal that is an integer multiple of the fundamental frequency.

      • If the fundamental frequency is f, the harmonics have frequencies 2f, 3f, 4f, . . . etc.
      • The harmonics have the property that they are all periodic at the fundamental frequency, therefore the sum of harmonics is also periodic at that frequency.
      • Harmonic frequencies are equally spaced by the width of the fundamental frequency and can be found by repeatedly adding that frequency. For example, if the fundamental frequency is 25 Hz, the frequencies of the harmonics are: 50 Hz, 75 Hz, 100 Hz etc.
      • Harmonics are related to waves of all types not just things we hear. From waves at the beach to radio waves they all have harmonics.

Different musical instruments sound unique due to some degree to the differing harmonic content of the sounds they make. A Piano, a Violin or a guitar all playing the same note sound different.

Human Voices also sound different due to differing harmonics. Compare a single voice to a chorus singing the same note. Generally the chorus has a richer sound due to the large harmonic content of all the different voices singing together.

The Human Voice

The human voice consists of sound made by a human being using the vocal folds for talking, singing, laughing, crying, screaming, etc. Its frequency ranges from 200 to 7000 Hz. The human voice is specifically that part of human sound production in which the vocal folds (vocal cords) are the primary sound source. Generally speaking, the mechanism for generating the human voice can be subdivided into three parts; the lungs, the vocal folds within the larynx, and the articulators.

Vintage facial nerve image

Details of facial nerves

The lung (the pump) must produce adequate airflow and air pressure to vibrate vocal folds (this air pressure is the fuel of the voice). The vocal folds (vocal cords) are a vibrating valve that chops up the airflow from the lungs into audible pulses that form the laryngeal sound source. The muscles of the larynx adjust the length and tension of the vocal folds to ‘fine tune’ pitch and tone. The articulators (the parts of the vocal tract above the larynx consisting of tongue, palate, cheek, lips, etc.) articulate and filter the sound emanating from the larynx and to some degree can interact with the laryngeal airflow to strengthen it or weaken it as a sound source.

Understanding Decibels

DB is a measurement unit that compares one (power, voltage, perceived Loudness) level against another.

The decibel (dB) is a logarithmic unit that indicates the ratio of a physical quantity (usually power or intensity) relative to a specified or implied reference level. A ratio in decibels is ten times the logarithm to base 10 of the ratio of two power quantities. A decibel is one tenth of a bel, a seldom-used unit.

What is “Good Production Sound”?

Good production audio is dialogue recorded at consistent levels that is clear and contains all of the “details” of an actor’s performance – a very simple idea.

Obstacles to recording good sound:

  • Poor mic placement.

  • Noise of all types – camera noise, traffic, buzzing lights, generator, inadequate lock up (other people in proximity to set), other electronics on location (eg. refrigerators), noisy costumes or set pieces (eg. creaking floors or furniture)

  • Footsteps (usually added later) on dialogue.

  • Overlapping dialogue.

  • Inconsistent performance or surprises (eg. actors shouting in one take and whispering in the next without warning or rehearsal.)

  • Poor shot design.

744T and Lectrosonics

744T Recorder and wireless receivers


Basic Booming Techniques

The Boom Operator’s most important task is to place the microphone where it needs to be when (exactly) it needs to be there.

As a general rule, until a boom person gains experience their total focus needs to be on ON CAMERA dialogue. If dialogue is NOT shot on camera ask for wild tracks. These wild tracks can save lots of time and energy in post.

  • Work with Camera to understand the framing.

  • Work with lighting and grip to deal lighting and shadow issues. KNOW what lights are affecting your shot. Work around them if possible.

  • Know the dialogue in the scene. This can make the difference between good sound and bad. This knowledge will let you anticipate the dialogue being spoken by an actor. In coverage shots this is less important unless the lines are very dynamic.

  • Rehearse. Take every opportunity to rehearse the scene and the boom mic placement. This rehearsal is very important for the mixer as well.

  • Anticipation. In scenes where there are multiple actors in a scene speaking and seen ON CAMERA, anticipation is more difficult and important.

  • “Mixing with the Boom”: This is one technique for recording very dynamic dialogue. The basic technique here is simple. Anticipate the higher level dialogue by moving the boom AWAY from the actor along the axis of the microphone. Increasing the distance of the mic from the actor effectively lowers the levels reaching the mixer.

  • Always wear headphones. Never work without them. They are your only connection to the audio quality, without listening you will not be able to make the subtle microphone adjustments needed to capture the all important details that make the difference between good dialogue tracks and great ones.

Listen! Listen! Listen! Both boom operator and mixer must hone their listening skills. Pay close attention during rehearsal and during the take.


Headphones for boom operator

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