Research: Wild track, ambient sound and room tone A wild track is audio recorded separately from visuals, intended to be used in case other microphones fail or don't pick up dialogue well enough. This will record the entire way through filming and will be synced up with the visuals later in post-production. Ambient sound is used to set a scene, and involves recording the sounds that can be heard in that location (e.g. people chatting at a cafe, cars driving past, plates clattering, etc.). Room tone can be a type of ambience, which is much more technical, and is achieved by recording a silent room. By including this room tone as a 'base tone', any additional sound tracks added on top will sound seamless and natural. If a room tone is done well it shouldn't be noticeable.
Ambient sound is crucial to a successful product because it provides audio continuity between shots, prevents an unnatural silence when no other sound is present, and establishes/reinforces a mood. These tracks are recorded on set, using an external microphone like the Zoom H4n Handy Recorder or the Rode NT4. It is recommended to use stereo audio (2-4 separate audio tracks) as this will create variation between the right and left speaker/headphone ear. Ambience doesn't need to be recorded at the high level of other audio recordings, and no one particular sound should stand out, they should all blend together. However, "close-up" audio recordings can be used to highlight particular parts of ambient sound (e.g. birdsong, insect buzzing). (from: www.mediacollege.com/audio/ambient/record.html)
Room tone is used as a sound bed to accompany any additional sounds added in post-production, for example re-recorded dialogue. If the new dialogue is recorded after filming in a separate studio, the difference in background noise would be enough to ruin the continuity, which is where room tone is needed to bring everything to the same level. It is recommended that room tone (inside) and air tone (outside) are recorded from every microphone and perspective used, as it is always better to record more than you need than to not have enough. Below is a recommended method for recording room tone, via www.creativefieldrecording.com/2015/05/13/how-recording-room-tone-improves-your-field-recordings/
Research: Foley artists
An essential role for the production of a successful film is a foley artist. They create most of the sounds we hear in a production aside from dialogue. Anything from weather to footsteps to punching can be created by foley artists and a mixer, with incredible attention to detail. The artists must consider every item a character comes into contact with, the type of shoes a character wears, and what exact surface rain falls onto, amongst many other considerations.
Below are some examples of how foley sounds are created, for example: glass for water freezing, sand for walking in snow, celery for bones breaking, and a demonstration of how the human voice can be used to enhance sound effects.
Research: Theme and incidental music
Theme music originated from opera, as they were performed in Italian and Latin, so the audience could only understand what was going on from the music. The purpose of theme music is to create brand familiarity and to make a product more memorable with a catchy theme tune that will get stuck in the viewers' head and relates to the show. This way, the audience is thinking about the product and so are more likely to watch it again. Theme music is composed specifically for one media product, and a lot of thought is put into the kind of emotions the piece wants to create, what themes of the show could be represented in the music and how different instruments can be used together. Theme music can be used for the product as a whole, and also for individual characters, so the audience can anticipate when they will appear on screen from the music. A famous example of this is the Star Wars theme tune and Darth Vader's theme.
Incidental music has a similar purpose to ambient sound, it sets the scene and adds to the immersive experience of the media product. For example, the creators of Black Panther learned a lot about African drum music and were able to incorporate this into the film to provide cultural context, to set the scene and to create atmosphere. Often, the visuals are edited together first and then a piece of music can be composed to fit with this and reflect the content of the scene, and it will also be perfectly in time to fit around any important dialogue.
Research: ADR
ADR stands for Automated Dialogue Replacement. It can be used for a variety of reasons, and is the process of dubbing over audio and syncing it up with a scene involving dialogue. Dialogue can be re-recorded because a microphone failed, didn't pick up the speech clearly, or if a microphone couldn't be easily hidden in an actor's clothes to pick up the sound. Sometimes if the team can anticipate bad audio, e.g. if there is a scene in a car or in a windy place, they will book studio time in advance to re-record the lines. But often, ADR is a last resort when the original lines cannot possibly be used.
Research: Voice over and scripted speech
Voice over is often used as a form of narration, in products like adverts, films, TV shows, and was very commonly used in trailers in the 2000s, but has become more of a cliche now. The purpose is to give the audience context to a scene, to tell them backstory or what a character is thinking. It is also very common in documentaries, a famous example being Blue Planet with David Attenborough. Voice over dates back to when a theatre production would have a narrator to do the same job, to set the scene and give context. Scripted speech is used for animated pieces, where actors don't necessarily need a full script, they just need to know what lines to say.