Hack 55. Cover Missing Audio with Room Tone

Sometimes, such as when a crewmember sneezes, you need to eliminate audio completely, but missing audio is immediately noticeable, even to those who have an untrained ear. Capturing "room tone" helps remedy this problem.

When you're editing, sooner or later you will discover an edit that must eliminate audio in your timeline. Trying to avoid a certain word that someone said, using footage that was recorded after a scene ended, or hearing a car horn honking in the background are just a few examples of how this can occur. When you remove audio from a scene in these circumstances, you wind up removing audio from the scene completely.

A complete absence of audio is both noticeable and disturbing to your audience. In order to fix the problem, you need to fill the hole with nondescript audio. This nondescript audio is often called room tone, because it is simply audio that has been recorded in a silent room. Even though the room might be "silent," there is audio to be captured, no matter how quiet it seems to be.

Ed Golya, a multiple Emmy award winning audio editor, likes to joke that he is going to use "the sound of clouds passing by" when he adds room tone to a scene.

5.6.1. Recording Room Tone at the Right Time

To anticipate potential problems while editing, the best approach to recording room tone is to record it while shooting a scene. The most common technique is to have everyone on the set stand silently for 30 to 60 seconds after completing a scene. During this time, record your surroundings to tape.

While doing this, you should be clear to everyone that you are recording room tone, possibly by holding up a slate or sign in front of the camera. If you do not make it easy for yourself or your editor to locate sections of room tone, it will be very frustrating. To use the section of room tone, simply locate it and use the necessary amount of audio to fill in where there is silence.

5.6.2. Stealing Room Tone from the Scene

If you do not have an intentional recording of room tone available, you might be able to steal some from elsewhere in your scene. To do so, play the raw, unedited footage for your scene and listen for sections where there is no movement, talking, or distinguishing characteristics (such as music lyrics).

Once you've located a section that is usable, copy the audio to your timeline. This solution can work well if you need to cover only a brief section of silence.

However, the longer the period of silence, the more difficult it becomes to locate an equal length of room tone.

If you need to, you might be able to place the same short section back-to-back several times on your timeline. Doing so essentially provides a longer fill. You will probably notice, however, that you can repeat the process only so many times before you notice the room tone repeating. It might sound odd, but you can hear room tone repeating, and when you hear it, you know it.

5.6.3. Recording Room Tone After the Fact

If you don't have room tone that was recorded while on set and you can't locate a decent section of audio to substitute, you can try recording room tone when you require it.

The best option in this circumstance is to return to the location where the scene was shot and record audio while there. Your hope is that the audio you record will be close enough to the original that it will be nearly indistinguishable from what was originally recorded. If you don't have access to the original location, you can try recording in an empty room and hope for the best outcome.

5.6.4. Covering Your Tracks

In order to not draw attention to the fact you've altered the audio, use small audio dissolves between the room tone you edit into the sequence and natural audio that already exists. These dissolves should be short; usually a few frames will suffice. It might take a little bit more work to smooth out your audio, but if you can keep your audience engaged in the scene, and not distracted by technical difficulties, you'll have a much better chance at keeping their interest.