Dialog Editing Part 2: The Elements of Dialog and Voiceover

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Post-production sound can be split into 5 categories: Voice-over, Dialog, Sound FX, Foley, Music.


Voiceover, or VO, is audio that is typically recorded in the studio. In a show (or film), it’s the featured voice that is explaining something to the viewer but you don’t see on screen. A good example of voice-over is commercials – where the voice leads the scene but it’s not necessary to know who is speaking to you. Here’s an example of a voice-over artist and the variety of work he does:

Voiceover can be recorded with a large-diaphragm condenser microphone but a lot of studios just use a boom mic at close distance. Occasionally, VO can be recorded during production with a boom or a lav. This is less than ideal, but sometimes it’s necessary due to location of talent, access, etc.

The “Dialog” category

Dialog (as a category) is made up of production dialog, ADR, and walla. 

Production Dialog

Production dialog is dialog recorded on-set (or when the camera is rolling). We generally just refer to it as “dialog”. Occasionally you’ll hear production dialog called “SOT,” which stands for sound on tape.

ADR stands for automated (or automatic) dialog replacement. ADR is studio-recorded dialog that is meant to replace (or add to) production dialog. In the US, we generally call it ADR but occasionally you will hear someone call it looping or dubbing. The terminology in other countries may differ. 

Here’s a couple short examples of how ADR is done:

Wikipedia says the ADR process may be used to:

  • remove extraneous sounds such as production equipment noise, traffic, wind, or other undesirable sounds from the environment;
  • change the original lines recorded on set to clarify context;
  • improve diction or correct an accent;
  • improve comedic timing or dramatic timing;
  • correct technical issues with synchronization;
  • use a studio-quality singing performance or provide a voice-double for actors who are poor vocalists;
  • add or remove content for legal purposes (such as removing an unauthorized trademarked name);
  • add or remove a product placement;
  • correct a misspoken line not caught during filming.
  • replace foul language for TV broadcasts of the movie. – Wikipedia


Walla goes by a few different names such as Group ADR or Loop Group. It’s when a group of people are in an ADR studio to record background voices for a scene (like other people at a restaurant). It’s sometimes just referred to as “group.” It’s unusual to see walla unless it’s a big budget movie or show (low budget tends to use library sound fx to cover walla).

The difference between ADR and Voiceover

The main difference between ADR and voiceover is how it’s recorded and used. Voiceover is meant to be pristine; it’s recorded on-mic at a close distance. Since ADR is replacing (or supplementing) what was recorded on set, it should match the sound of the original mics (as much as possible). Boom mics are recorded at more of a distance for ADR than voiceover.

The difference between ADR and Dubbing

If we’re taking an entire show (or film) and re-recording it in another language, in the US that’s called dubbing, not ADR. Dubbing is recorded similarly to voiceover where it’s in a studio, close-miked, and trying for the best audio quality possible. We won’t get into dubbing in this course but many of the editing and mixing techniques would apply to it. Wikipedia also has a fantastic article about dubbing that looks at how it’s done in over 30 countries.

Here’s some clips of a show that was mixed in English then overdubbed in Japanese. Notice how they kept all the non-English elements – music, sound fx and Foley – to use for the Japanese version. (this video has some violence from 1:30 on.)

Production FX

There is one loophole when talking about production dialog. Production FX (or pfx) are sound fx that are captured with the production dialog. For example, if a character says a few lines then closes a door, the door close would be considered pfx. PFX are generally removed from the dialog track and moved to sound fx tracks (labeled “pfx”).

The reason this is important is if you’re working on something with a foreign version (like the above video). In a foreign mix (“M&E”, or music and effects), all the dialog is stripped from the mix so you may have to recreate many sounds that were missing. If there’s sounds that already exist in production and sound good, this can save you time needing to add it to the foreign version later.

PFX sounds could be footsteps, kissing, a chair creak or something breaking – basically any specific sound that doesn’t have audible dialog. If it’s noisy or the quality isn’t great then there’s no reason to separate it. It’ll probably need to be covered by sound fx, regardless.

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