One of the biggest issues in post-production sound, and truthfully any kind of audio work, is actually not anything to do with the sound itself; it's the communication between creatives. In this article, I want to clear up a few of those potential communication issues by going over five terms that are integral to the workflows in sound for picture.

While they might seem basic to some, understanding these concepts thoroughly will allow for better communication (and therefore better work) throughout the entirety of the creative process, from recording through the final mix.

I. On-Axis vs Off-Axis

The first term is all about getting the best sounding recordings as they’re being captured. Recording a sound “on-axis” means you’ve got a microphone pointed in the optimal direction to pick that sound up...assuming you want it picked up well in the first place. The concept goes beyond just pointing a mic in the “right” direction; by accounting for a mic’s pickup pattern and placement, along with its sonic character, you can drastically shape the way a listener will perceive those sounds from the start.

The pickup pattern of a mic will dictate where a sound transitions from on-axis to off-axis. For example, omnidirectional microphones are designed to pick up sound well in every direction, so technically any recording that you make with it is going to be on-axis and will therefore sound the “best” the mic is capable of. Using more focused polar patterns like cardioid shapes (standard, super, hyper), sounds that occur outside of that “optimal” pickup space will noticeably decrease in fullness, frequency representation, loudness, and perceived distance from the mic. This is of course most pronounced with shotgun mics, which are highly directional in the front of the mic while rejecting as much sound as possible from the sides and rear.

With that concept in mind, you can make decisions about how you're going to record something depending on your environment. An obvious example of this might be angling a shotgun mic away from roads or generators when recording dialog on set, but it’s been highly useful for more complex recording situations like making a car drive-by sound more aggressive simply by turning a mic slightly in the “away” direction of the vehicle’s trajectory. This simple change will reject more of the incoming sound and favour the actual pass to seem more sudden, punchier, faster...maybe even a little furious...as is necessitated by many films.

It can also be really helpful in troubleshooting issues with sounds; simply knowing what off-axis or on-axis recordings sound like in case a microphone is accidentally pointed in the wrong direction will help narrow down potential problems in a hurry. Or, if a sound is supposed to sound distant or off-stage, deliberately angling the mic away from the source can help achieve that without changing physical distance or relying on processing.

2. Foley

The next term to know is foley...and again, that might seem basic, but I've heard plenty of working professionals refer to the entire soundtrack of a film as “foley”, when it only applies to a particular layer of that soundtrack. In post sound, foley is the re-performance and recording of very specific and often mundane, everyday movements that don't get captured on a set. In most cases, it is substantially more time-efficient and natural sounding to re-record performances of certain sounds rather than rely on cutting them from a library (footsteps, cloth movement, chair sits/ups, drink/utensil handling, etc) because of how surprisingly nuanced these actions can be. Most sound library material is difficult to make work at best.

Now I might be biased here, but I would say that between sound and visuals, the sound is the more important component in creating a captivating experience. A professional sound edit/mix can bring a lacklustre picture to life, while poor sound can absolutely ruin even the most perfect visual experience. While a lot of different elements are combined to make audio immersive, it’s my personal opinion that foley is one of the single biggest differentiating factors between cinematic experiences. It can breathe life into an otherwise empty soundtrack, or make scenes feel totally empty and uncomfortable when it’s not done well or done at all.

Horror films are generally great examples of this. When you next watch one, turn the sound off for a few of the creepiest moments. Suddenly, those moments impart almost zero fear or meaning. It doesn't seem scary at all, it's just...maybe gross, or possibly a bit unsettling...and that’s really it. As soon as you layer in really good sound, these same moments spring to life and can be outright terrifying - especially all those little details of the floorboards creaking overhead, or when everything gets really quiet and you can hear the cloth shift as someone turns their head to look over their shoulder. All because of sound well-done. And if horror isn’t your preference, imagine how lifeless all the nature footage in Blue Planet or National Geographic films would be without any animal foley.

Obviously, it’s only a portion of the work that goes into the creation of a professional soundscape, and it takes the right balance of many moving parts to make a piece of content sound great, but foley is a really important thing to be attentive to because it can very easily make or break a viewer’s experience.

3. Sound Editing vs Design

A lot of people get these two terms mixed up...and to be honest, it's really hard to find a definitive line between the two. I hear many creatives referring to one as the other, or to the entire soundtrack of a piece as “sound design”. While there are many points of overlap, editorial and design are unique and different parts of the post sound process and knowing which one to ask for or reference can be helpful in communicating needs, problems, and creative decisions. There are a few different opinions on where to draw this line depending on who you ask.

My general principle (and that of many of my peers) is that when it comes to sound editing versus sound design: sound editing applies to cutting and syncing sounds from a collection of existing material. The fundamentals of guns, explosions, or cars are generally going to fall into the category of sound editing where you're choosing elements from a library of sounds and syncing them with video. Layering recordings of a trigger dry fire, low/mid/high explosion elements, metal movement sweeteners, and a shell casing drop to create a gunshot is sound editing.

Sound design generally applies to creating new sounds that don't really exist in the “real world”, either through recording and creative processing or through synthesis. This can range from layers and textures in ambience, to stingers or slams for cinematic emphasis, all the way to extraterrestrial vocalizations and space ships. However, it can apply just as well to layering and manipulating sounds that fundamentally change how they are perceived - layering aggressive animal vocals under-car engines to add intensity, for example.

The differences between the two can be subtle, and the dividing line can entirely depend on the individual or crew working on a given project, but it is important to note the nuances in skills, techniques, and creative ideas behind the two disciplines.

4. Sound Mixing vs Re-recording Mixing

The fourth term to know is one that a lot of independent filmmakers - and especially companies or corporations that are not film/TV production houses - mix up all the time. That's the difference between sound mixing and re-recording mixing.

Sound mixing in the professional world specifically applies to recording and mixing sound on set. It’s the physical act of actually capturing all that audio from on location during the filming process to get the best possible representation of any performance taking place. Many people also refer to this as “location sound mixing”, which might be an even better way to avoid any unnecessary confusion.

Re-recording mixing, on the other hand, is specific to post-production sound mixing, when all the different sounds that have been recorded, edited, designed, and synced with video are brought together and blended into a mix that viewers will hear.

5. Room Tone

The final term is extremely important in production sound, dialog editing, and re-recording mixing; that is room tone. Room tone is...just that - a recording of silence in a room that’s being filmed in - and it’s used in post sound to fill gaps or smooth cuts in production dialog to give the seamless, smooth, “all in one take” feel that every film or TV episode aims for.

It should be recorded for every location being used, and ideally should be captured in the same conditions as the actual filming so that the noise floor of the recordings will sound as identical to the rest of the production dialog as possible. That means using the same microphone and recorder in the same rooms, with anyone who was in the room during filming present, matching, which lights or generators may have been turned on, etc. The big difference of course: absolutely no movement or talking.

This is one of those nuances of sound that everyone, no matter their role in a production, should be familiar with. Clean, pristine room tone is absolutely crucial to editing dialog, because there will always be cuts between different mics, takes, characters, perspectives, and/ or scenes that need to be smoothed out to sound like a single recording rather than many pieced together. It is far easier to use authentic recordings of silence from on set to do this than it is to recreate room tone from production dailies...and while there are some tools out there that can sort of “generate” room tone to some extent, they never sound quite as organic or as good as the real thing. Plus, even if you're not using it to cut in between different pieces of audio, room tone can be used as a learning source to train denoising plug-ins on what might need to be removed from recordings later on.

Again, these terms may seem a little basic to some, but the fundamentals of sound are truly important; they’re what all of the other complicated ideas are based on. The highly generalized roles in many independent projects (and the exact inverse on major studio productions) bring all kinds of knowledge gaps and communication challenges between creatives and departments, so having an understanding of what these concepts are and why they’re important can make all the difference.