Is there anything worse than hauling your audio capture back to the editing bay, only to find every inch of it is plagued by the hum of a nearby air conditioning unit?

It's a tale as old as time itself. Room tone is the bane of DIY filmmakers everywhere, but that's just because they don't yet know how to tame the beast.

In this article, we'll dive into the basics of room tone, explaining what it is, what it's for, and how to record it.

What Is Room Tone in Filmmaking?

Filmmakers preparing to roll.
Image Credit: Author Unknown/Wikimedia Commons

Room tone, also known as ambient sound, is the natural miasma of sound that exists in any space—enclosed, outdoors, or otherwise. Envision the difference between an empty room and one that's fully furnished; reverberation will be one obvious difference, but that will rarely be all that you're contending with.

Room tone also refers to a recorded sound clip, taken ideally at the beginning of each camera set-up. Any time the camera changes its position, even only by a few feet, a new specimen of room tone should be recorded to reflect the change.

Why You Need Room Tone

No matter how quiet the scene, there is no dead air in professional filmmaking. It's jarring and abrupt, something that your audience will perceive and cringe at, especially if left in your project by mistake.

Room tone is like a band-aid that you can patch over any weird accidents that need to be removed from your production sound—like dropping a wrench, or somebody's phone going off in the middle of the shot, for example. It's both a safety net and a resource when editing your project's sound bed.

For filmmaking that involves dialogue or interviews of any kind, room tone is non-negotiable.

What Is Room Tone Good For?

One man captures the wild.

One common problem that makes room tone a lifesaver includes masking the sound of airplanes flying overhead and other subtle, insidious sounds that the untrained ear might not notice until they're already reviewing the footage.

Let's look at a few more examples. Any of the following are easily taken care of with solid room tone backing up every clip. All you need is the underlying bed to heal over any lapses in your production audio.

Large Appliances and AC Units

A run-in with this classic DIY filmmaking nightmare will not be one that you soon forget. Little is more frustrating than realizing you forgot to unplug something droning on in the background. Identifying and disabling or muffling sources of sound like this is a must the second you step on-location.

Cell Phones and People Talking On-Set

Actors are professionals; when somebody yammers all over their moment, they can usually keep their composure and give you some type of performance to work with.

If your shot has been interrupted by an A and B conversation, room tone makes it easy to C your way out; it lets you capitalize on every last frame.

Wind and Other Weather Conditions

When shooting outdoors, a random gale of wind may blow right through your actor's performance. Room tone will save this performance, and perhaps the scene, as well. If it's raining outside, you'll want to double down.

Lots of extra, generic rainy day room tone to choose from will ensure that you're never editing yourself into a corner and will always be able to salvage the best takes.

Airplanes and Other Commercial Vehicles

Cars, large trucks, ambulances, and even cyclists gunning it nearby may all punctuate your shot. The problem with airplanes, in particular, is that the sound that they make changes as they get closer and further away at a distance—it can be really difficult to ramp off an effect or equalizer as this happens.

Removing the issue entirely and filling the gap with pitch-perfect room tone is usually the best solution for those who do not specialize in sound engineering.

Editing Dialogue in General

When editing interviews or narrative scenes, you'll likely be slicing and dicing, even if you're shooting a project with lots of oners, or one-shot sequences.

Room tone is indispensable here for the same reason as it is when simply cleaning up your footage and ridding it of unwanted artifacts. For every gap between clips of media, you'll need room tone to ease the transition.

Wild Lines, ADR, and SFX

These techniques sound a lot more realistic when you include real room tone from the day that you shot the footage.

his applies to anything that you add to your project's sound bed that didn't happen on set—sound effects, voiceovers, all of these melt into one homogenous-sounding soundtrack with the appropriate room tone backing.

The "Silent" Portions of a Project

A pensive reverie? A tranquil morning? A moment of hair-raising suspense before the big scare? As we mentioned before, silence is never absolutely zero in filmmaking. You'll need room tone to act as a stent that takes the audience from here to there seamlessly.

Related: The Best Shotgun Mics for DSLR and Mirrorless Cameras

How to Record Room Tone

An AC about to slate a shot.

You usually won't be able to get away with only recording room tone once over the course of your film shoot. Which is fine, because recording room tone doesn't take long and requires very little labor.

It's best to refresh your room tone for each shot and set-up for a few reasons, the primary one being the fact that rearranging your lights (and any other flats or furniture) will cause the ambient sound in the room to change.

To record room tone, you need to wait until you're just about to shoot your first shot of the day. Without reshuffling the room, make an announcement for everybody to simmer down.

Put your mic or mics into position, similar to how they will be configured for the shot itself; you or your sound person may want to take this time to listen to what they're picking up. If anything sounds suspicious, now is the time to turn off that fan in the other room, before you start shooting the scene.

Related: How to Make Your Project More Cinematic

When everything is ready to go, hit record. 30 seconds of room tone should have you pretty much covered. You can then proceed to shoot the shot as usual.

When moving on to another location, even within the same house or building, the need to grab new room tone will be obvious. If you're simply flipping the world and grabbing an opposing over-the-shoulder shot, the change in room tone will probably not be as significant. Still, better safe than sorry.

Honestly, the most difficult part will usually be keeping everybody quiet. It really is that simple—room tone is just a sample of the ambient audio conditions on set to keep for when it's time to cut the project. No more, no less.

Make It Sound Like Hollywood, Baby

Room tone is like keeping a little piece of your production day with you in your back pocket. It makes repurposing shots a very simple matter; you can author new parts of your scene entirely with the right creative footwork.

Don't forget to grab some room tone for your next project—thank us later, and watch your work shine.