Audio post-production is an intrinsic part of the filmmaking process and gives a movie its signature flair


If you’ve ever watched the credits after a movie ends, you must have seen hundreds of names scrolling up the screen. Filmmaking is perhaps the most collaborative art form, and the greatest films are a result of a dedicated team of skilled artists working at the top of their game. In these, many belong to the audio department of a film. Over 40 people are credited in the sound department alone for the 2018 Oscar-winner for Best Sound Mixing and Editing, Dunkirk. This doesn’t even include the many technicians, engineers and musicians who worked on the score written by Hans Zimmer.

Audio post production is a sprawling universe, and includes the creation and manipulation of audio synchronised with video. The production audio, which is the audio recorded as filming/shooting occurs, is edited and finished as required, to create the desired effect and feel of the scene. Most aspects of audio for moving picture occur during the post-production phase—it includes sound design and addition of sound effects, amongst a long list of other touches. This applies to TV, cinema, and commercials.

One major aspect of audio post production is the use of ADR, or automatic dialogue replacement. Sometimes the original, or production audio, lacks in performance or quality, and the actor or actors are brought into a sound studio to record some or all of their dialogue from the project. Cleaning up dialogue that was recorded on set, often takes time if the recording environment wasn’t quiet/suitable or acoustically treated. Noise elements are normalised and other elements such as Foley, music, and voiceover, are also added during post-production.
Reworking and enhancing voice-based media is prevalent in the form of noise reduction and volume normalisation. Sound recording devices with different characteristics and capabilities such as dynamic range, has led to increased demand for consistent sound. With many techniques being adjusted specifically for vocal audio, the field is becoming more understood as unique to music production. The automation of post-production vocals is demonstrated by tools which use a combination of machine learning, analysis and reactive mixing. All these sonic elements come together in the post-production audio studio.

Transformers is a great example of creative sound design. The inhuman alien machines had a hundred thousand sound effects in the movie, all achieved by a combination of hundreds of smaller sounds that created distinctive sounds in each scene. These smaller sounds were either real recorded sounds of pots, metal bins, or cutlery. These sounds were then digitally manipulated and synthesised by use of oscillators, filters, and lots of other digital tools.
The above example is that of something that doesn’t exist in the world, but even real-world sounds need to be edited and designed so as to seem appropriate for a given shot. Walking footsteps, the rustle of leaves, doors being opened, ambient sound—all are examples of real sounds.
Spot effects are intended to cover obvious sounds on screen such as doors, vehicles, fist punches etc. Background effects are used to widen the stereo image of your film, and surround the viewer in the mix. They are often long, consistent and looping sounds that can give the audience a different perception of what is on screen. For example, if a scene has howling resonant wind it may feel empty or scary, but if it has tweeting birds it may feel more peaceful.
Once the sound design is complete, dialogues, music and voiceover has to be paid attention to. The background score, for example, should be appropriately softened under any dialogue and voiceover so that there is a fine balance between the sound effect, music, voiceover, and dialogue elements. This is known as mixing.
It is important for a sound designer to be sensitive to sound in his environment. For instance, footsteps in an empty parking lot will carry a level of echo, while footsteps on a carpeted floor would sound muffled and soft. Sounds have to be believable. Enter: acoustics. Every action has a different impact when performed in different rooms/locations. And if these small but important considerations are missed, the scene would sound off.

Foley is the reproduction of everyday sound effects that are added to video to enhance audio quality. These reproduced sounds, named after sound-effects artist, Jack Foley, can be anything from the swishing of clothing and footsteps to squeaky doors and breaking glass. Foley sounds are used to enhance the auditory experience of the movie. Foley can also be used to cover up unwanted sounds captured on the set of a movie during filming, such as overflying airplanes or passing traffic.
Foley artists recreate the realistic ambient sounds that the film portrays. The props and sets of a film often do not react the same way acoustically as their real life counterparts. Footsteps, movements, and even the more seemingly insignificant sound effects are meticulously performed and recorded—sometimes with props other than the one causing the sound—to mimic the required effect.

The sound captured by the sound crew, on set, may not necessarily be crisp and noise-free. Once recorded, the dialogues need to be meticulously cleaned up of any unwanted distortions or noise, and have to be ‘filled’ so as to prevent any unwanted drops in the ambient tone. Dialogue editing involves trimming and extending clips, adding fades, copy and pasting, swapping out takes and rendering audio repair effects onto clips. Removing any inconsistent and uncomfortable sounds allows the re-recording mixer to perform the mix with smooth and clean dialogue tracks. This is a crucial step in any sound post-production environment. ADR

Automatic dialogue replacement, also known as ADR, is a process by which dialogues are re-recorded in a studio by the actors reciting their lines alongside the original performance. It is a method of superimposing dialogue that has been recorded in a controlled, acoustically treated space. Location dialogue oftentimes becomes problematic when the ambient noise of the environment is too high, the equipment malfunctions, or when the talent is just not projecting over what should be background noise. This eliminates background noise or any other external noise that may have interrupted the sound. Sometimes, dubbing is required for certain language hiccups. In other cases, ADR is used to replace an actor’s vocal performance, which is especially done in musicals where a professional singer replaces an actor’s voice.
Using the same mics, the same mic placement, and recreating the environmental conditions of a scene in their digital audio workstations, enables audio professionals to use partial ADR, which ultimately allows them to achieve a much better take of a particular scene that maybe wasn’t as good as it should have been given a number of aspects the production was not able to control during the filming process.


Mixing is the process of taking all of the elements within the soundtrack and balancing and assembling them into a cohesive tapestry of sound. The re-recording mixer, also called dubbing mixer, will use a combination of software tools to sculpt the mix, ensuring that dialogue is consistent, the Foley is realistic, sound effects have an interesting surround field, the music blends well and there is a pleasant tonal balance overall.

The final mix must achieve a desired sonic balance between its various elements, and must match the director’s or sound designer’s original vision for the project. For material intended for broadcast, the final mix must also comply with all applicable laws governing sound mixing. The first part of the traditional re-recording process is called the ‘premix.’ In the dialog premix the re-recording mixer does preliminary processing, including making initial loudness adjustments, cross-fading, and reducing environmental noise or spill that the on-set microphone picked up. In most instances, audio restoration software may be employed. For film or television productions, they may add a temporary/permanent music soundtrack that will have been prepared by the music editor, then the resulting work will be previewed by test audiences, and then the film or television program is re-cut and the soundtrack must be mixed again. Re-recording mixer may also augments or minimises audience reactions for television programs recorded in front of a studio audience. In some cases, a laugh track may augment these reactions.

During the ‘final mix,’ the re-recording/dubbing mixers, guided by the director or producer, must make creative decisions from moment to moment in each scene about how loud each major sound element should be relative to each other. They also modify individual sounds when desired by adjusting their loudness and spectral content and by adding artificial reverberation. They can insert sounds into a three-dimensional space of the listening environment for a variety of venues and release formats. Today, films may be mixed in ‘object-based’ audio formats such as Dolby Atmos, which introduces a heightened atmosphere within the sound field with the introduction of ceiling speakers and the elimination of audio channels. Mixing sound for picture involves a lot of artistic performance.
Another crucial element to mixing is the distance perception of sounds. Dialogue is usually situated at the centre of a mix, but will have effects added to push it further from the viewer when characters are further away visually. The remaining track will fill and take advantage of whatever ‘percieved space’ the given speaker system and delivery specification provides.

Imagine a Rajnikanth-starrer movie, in which he performs a stunt scene on a busy street—think: car sirens wailing at a distance and indistinguishable voices being heard across the street. He jumps across the roof of a bungalow, and we hear his leather jacket snapping as it cuts through the air. Then comes the fight—the punches, grunts, thumps and slams punctuated by blaring horns and sharp percussion from the soundtrack. All this drama that audiences yearn for, is essentially contributed to—by sound effects and post-production. Without these sounds, the mere video would carry no suspense or excitement. Sound amplifies the emotion in a given scene, and helps evoke the actual feel of the movie or ad film. In addition to video, the audio needs to be given equal importance. That is how prominent the role of audio post-production is!

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