Post Scripts
Dialog Replacement in Films and Television
By Dane Davis

One of the primary goals of film is to create the illusion of consistent time and space onscreen. As with the visual aspects of the film, the sound — including dialog — must support this illusion. When a production recording of dialog is unusable due to intelligibility or noise problems, it is replaced by a clean recording that precisely fits the existing picture. The process of recording this replacement dialog is called Automated (or Automatic) Dialog Replacement (ADR), or looping.

In ADR, the original actor or actress recreates his or her character’s vocal performance, one line at a time, in a sonically controlled environment. This technique, though often necessary, makes it considerably more complex for sound editors to maintain the overall illusion of consistency.

Making It Clear
ADR is most commonly used when noise in the production environment makes it impossible to understand the dialog that was initially recorded. Despite the best efforts of the production mixer on location, sometimes the level and timbre of other sounds mask the actor’s voice, making the dialog unintelligible. A key function of the ADR supervisor is assessing this threshold of intelligibility, and then persuading an often-reluctant director and picture editor that ADR is needed in a particular scene.

When an audience fails
to comprehend what the
character is saying, the
power of any performance
can be lost completely.
Understandably, directors are usually not enthusiastic about tossing out a performance captured on the set in favor of an ADR reading made in a sterile, out-of-context recording studio. But when an audience fails to comprehend what the character is saying, the power of any performance can be lost completely. When we watch a movie, we want to understand the dialog — and sometimes ADR is the only way to make this possible.

A very noisy line of production dialog in sync with
a cleanly recorded ADR replacement.
In contrast, there are times when the director actually wants to replace the performance of a line. If the right reading was never quite achieved on the set — or more commonly, if the reading doesn’t feel right in the flow of the edited scene — the ADR supervisor will “cue” that line for looping. Sometimes story changes require the dialog to be altered. “She” needs to be “they,” or “going to shoot him” must be changed to “already shot him.” Again, ADR makes this type of change possible. Entirely new lines are often added offscreen or over characters’ backs, usually for expositional clarity or reinforcement.

Matching Voices to Action
Sometimes a director believes that an actor isn’t capable of delivering the vocal performance needed for a character. When the actor you see onscreen has had his or her voice replaced by a different actor, it’s called “revoicing.” A casting call is sent out to actors with strong loop-stage experience. When the revoicing actor has been cast, the ADR proceeds normally. Fortunately for everyone, this is rare. It is more common for “voice-alike” actors to be brought in to record temp lines for audience previews, to save the lead (busy and expensive) actors from having to perform lines of dialog in ADR that may not make it into the final cut.

Entirely new lines are
often added offscreen or
over characters’ backs.
When actors overlap each other on camera, or when one is on camera and the other is offscreen and the picture edit doesn’t support this superimposition, then both the outgoing and the incoming words need to be replaced in ADR. Assuming that the dialog editor can’t spin some magic with alternate takes or audio surgery, both entire lines from both actors — and possibly the surrounding lines as well — are cued for replacement. With skillful editing and mixing, most of the production dialog might be saved — but it is always best to record extra dialog around the problem area, to make the ultimate transition between production and ADR as transparent and unnoticeable as possible. This applies to all ADR, not just overlap problems. An editor can always use Pro Tools to shorten the part of the loop line that is actually in use, if the transition allows it, but cannot lengthen it if the material does not exist.

Breaths are also often the victims of actors jumping right in on each other, even if the words themselves are intact and separate. Again, if the dialog editor doesn’t have the material to reconstruct the natural breathing patterns of the people in close-up, each actor (or a vocal impostor) must recreate that rhythm on the stage. In scenes where the characters are exhibiting exertion, their huffs, puffs, gasps, and other respiratory actions — called “efforts” — often need to be recorded cleanly to project their dramatic power to the audience.

Walla Sound
When the lead actor does not have the time or inclination to provide utterances like breaths, a vocal stand-in may be brought in. These specialized “heard-but-not-seen” performers are generally part of a “loop group.”

Actors in the "Loop Group" performing in sync to projected
Also known collectively as a “walla group,” these “groupers” are brought in to provide voices for everything but the primary bodies on screen. On the set, secondary actors and extras are usually asked to mouth their words without actually uttering audible sounds. This helps keep the set quiet to isolate and capture the performances from the principal characters in each scene. Baseball fans, diners and waiters, kids in the classroom, detectives at the crime scene, families picnicking, strip-joint customers — the sounds of all these people in the final movie are typically recorded later, in ADR. This vocal ambience is generally called “walla,” as in “wallawallawallawalla.” The audience does not really need to understand anything these people are saying, but the flavor and tone need to be convincing. Everyone needs to believe that they are in a real classroom, crime scene, or ball game, and the loop group actors provide that illusion. It becomes especially important when scenes take place in geographically specific or “foreign” places.

The group leader (who usually acts with the group onstage) finds actors that can speak, if not actually converse, in a particular language and a particular regional accent. The actors then write or improvise suitable dialog within the setting of each scene. A single movie may include such settings as a Parisian café full of academics, a factory in Sao Paulo, a corporate board meeting in Manhattan, a party in Beirut, a Jamaican political meeting, and a beach in Malibu. Once the ADR supervisor has determined the film’s needs, the walla group leader assembles the smallest possible group (usually between eight and sixteen actors) that can still provide all the linguistic and socioeconomic flavors for the recording session. Requirements for later international distribution also must be considered when mixing various languages and accents together.

Spotting Cues
In the beginning of the post sound process, the ADR supervisor looks at the entire movie with the director and picture editor in what is called an “ADR spotting session.” Usually the editor already has a list of new lines and replacement lines that have been discussed during the editing process. During the spotting session, all these cues are discussed, and the ADR Supervisor usually has lots of suggestions for loop lines after listening to the editor’s track for anything unclear. Other vocal elements for TV sets, radios, phone conversations, etc. are also added to the cue list, even if they are “to be written” (TBW) later. These TBW lines are placeholders for the casting and scheduling of actors. At the end of the spotting session, the supervisor takes all this information and compiles a master ADR cue list, with exact start and stop frames for each line, which is printed out for approval and reference by the director, editor, and producers.

About ten lines per hour
are usually accomplished
on the ADR stage.
At this point, the post production supervisor or a producer calls all the actors’ managers or agents and tries to schedule them in an efficient series of ADR sessions. This is a challenge, given the schedules of busy actors and their ever-changing geographic locations. Sometimes the director and ADR supervisor have to fly to another city to record an actor on location shooting a new project.

In a looping session, the actor and the ADR mixer get printouts of the lines that the actor must record. About ten lines per hour are usually accomplished on the ADR stage, depending on how many takes the actor and director require. Some actors have a natural gift for this awkward process, while others find it excruciatingly difficult.

Pro Tools Saves the ADR
Technically, the ADR process has become somewhat simpler than it used to be, thanks to applications such as Pro Tools. Not that long ago, a physical loop of film had to be cut for each line to be replaced. These have now been replaced by virtual loops played on a computer screen. As with the original method, the actor watches the picture and synchronizes his or her voice to the action as the mixer records it.

ADR Supervisor’s programming notes
or “Cue Sheets” for principal character
and ADR Group lines.
To help the performer get into a rhythm leading into the “first mod,” or initial sound modulation of their line, a short sequence of beeps has become standard on the ADR stage. The actor hears “beep...beep...beep...” and expects to start the line on the (silent) fourth beep. Session mixers will vary the timing of the beeps relative to the line to find the most comfortable lag time for each actor. The actor then rehearses with the beeps and the production reading until he or she is ready to record a synchronized take. Some ADR stages also have visual “streamers” that move across the screen in anticipation of each cue.

As each take is recorded, the ADR supervisor notes the performance, the sync accuracy, and the actor or director’s preferences. Some supervisors will record a few sync takes, then let the actor keep performing the line “wild” until he or she achieves the original on-set character nuance. This method can be a lot more time-consuming for the ADR editor, but with “sub-frame” editing in Pro Tools, miraculous synchronization can be achieved. Takes that feel perfect in emotional tone and inflection, but look “rubbery” unedited against the picture, can be reshaped to perfection with editing tools like the Synchro Arts VocALign plug-in.

Some vocal actions, like the mouth shapes for the sounds “p,” ”b,” “v,” and “m,” require very exact synchronization or they look completely wrong, even to a layman’s eye. Other consonant and vowel sounds allow a bit more flexibility — it’s often possible to “cheat” a different rhythm, or even different words, onto the actor’s lips and mouth. Sometimes a line looks more natural with a looser synchronization than with an over-edited tight fit. Maintaining the balance between natural performance and lip-sync is the primary challenge of the ADR editor. With experience, the editor masters this threshold of believability.

Keeping It Subliminal
Besides keeping the ADR session running as efficiently as possible, the ADR mixer’s job is to match the acoustic quality of the production recording as much as possible, to make it easier for the re-recording mixer to merge production dialog and ADR. The mixer needs to keep many variables in mind, including what type of microphone was originally used, the room acoustics, the axis angle of the mic, and the distance from the mic to the actor’s mouth. If the original production mixer used a lavalier, a shotgun, or a less directional mic on a boom, then the ADR loop must be recorded with a similar mic.

The most critical consideration
is microphone distance.
The most critical consideration is microphone distance. Placing a microphone too close to the actor creates the “proximity effect,” increasing low-frequency response. The resulting sound can be so different from the on-set recording that it can’t be matched in a natural way. Some ADR mixers have a gift for emulating the original sonic quality of the production dialog. That similarity can make a huge difference for the audience. Ideally, an ADR line shouldn’t even be noticed by the audience. When the illusion of aural consistency is broken, it can take several more lines for the viewer to fall back into the make-believe world on the screen.

Once all the necessary ADR gets recorded and edited, the dialog re-recording mixer matches each loop line to its surrounding production, paying special attention to sound level, equalization, and room acoustics. This is where the illusion of continuous time and space is ultimately achieved — or not. When it is achieved, all the dialog in a film — whether originating in production or ADR — will be accepted without question as happening in a continuous sequence, right where the camera is pointing. A lot of work goes into that aural magic act.