Sometimes, despite your best efforts to create the optimal environment for filming each time you make a video, you’ll discover unforeseen problems. These issues can crop up just as often in your audio recordings as they do in your video. In fact, even in a completely isolated area that is free from noise, while reviewing your footage you may discover the occurrence of certain anomalies in your sound recordings.

Whether you’ve recorded audio track(s) together with the video or using an entirely separate system, it’s impossible to account for every error you’ll encounter. Things such as white noise produced by fans or the air rushing through ventilation ducts can go unnoticed while you’re in the middle of a set, only to show up in your production audio later on. Interference from electronic devices can often be inaudible, but may somehow disturb your camera’s operation. Wind noise from an outdoor shoot can make its way to even protected microphones, causing drop-outs and annoying crackles and pops.

Thus, you may need to resort to a process called overdubbing, which involves inserting sounds during post-production to replace the corrupted or unintentionally altered sounds captured on set. When you overdub an actor’s dialogue, the recorded result is called a voice-over. The term is also sometimes used to describe narration from someone ‘outside’ the scene, but in this case we’re speaking specifically about voice overdubbing of an actor who appears physically within the scene.

Techniques For Recording Voice-overs

I approach recording vocal overdubs for a film or video in almost the same way I would go about grabbing vocals from a singer. The main difference is in the pacing and sensory input you’re providing to your actor; after all, the most favorable conditions for overdubs would involve the actor being in the same mood or ‘state’ that he/she was in when the original scene was shot. My recording setup for overdubbing is described below.

Recording Studio

I have two separate rooms – a control room and a ‘sound booth.’ The sound booth is really just any space that can be closed off with a door. In my old apartment, it was a walk-in closet. Now I use a spare bedroom. The control room is where my DAW is located, and thus where I am located during the recording.

Microphones

I place my studio vocal mic in the sound booth on a stand to match the actor’s height as closely as possible. Use whatever microphone you have available to you – even a cheap lavalier mic from radio shack can work. I then have another vocal mic in the control room with me; this is called a ‘talk-back’ mic, and it allows me to communicate with my actor without having to yell through two closed doors and a hallway and interrupt the flow of the session (or the quality of the recording, for that matter).

Other Equipment

The actor and I both wear “earmuff-style” headphones, the type with full bass response that covers and makes a seal around your ears. These headphones are both connected to the same audio source, and I use a splitter to send signal to both at the same time.

Placement

Actors should be standing at all times, even if they are overdubbing a scene in which they were sitting, slouching, or even lying in bed. This promotes anatomically correct use of the diaphragm and allows the actor to employ a larger range of movements to enhance their performance.

A windscreen placed between the mic and the actor can help cut down on unwanted pops and clicks from some of the sharper hits, such as “p”, “t”, and “s” sounds. Whether using a windscreen or not, it may sometimes help to place the actor at an off-angle to the microphone to prevent direct airflow onto the mic while speaking. As a quick test, have the actor start talking and place your hand in front of their mouth, cupped slightly but not touching their face. Over a few seconds you will start to feel whether they tend to project air in certain directions more than others in their normal way of speaking. Use this to determine their angle and placement in relation to the microphone.

Sensory Input

In order to insure the most accurate performance, the actor should at least be able to hear him or herself during the scene, if not also having the added benefit of seeing the edited footage. I find that it’s easy enough to just let the actor listen to each line one at a time, without providing a video feed from a secondary monitor and a long cable connected to my workstation at the other end. As long as you can let the actor hear what they’re saying and use your talk-back mic to coach them into state, you should be able to get a decent performance that is similar in pitch, speed, and tone to their original.

Pacing

This varies from actor to actor. Some actors prefer to have repeated playback in their headphones so they can hear the line over and over and practice speaking it again directly over top of it. This way they are sure to get a result that rhythmically matches the original. Other actors just like hearing the line a few times and then repeating it on their own, without any background noise to distract them from their current performance. Work with your actor to figure out what makes them most comfortable.

Example

Coming sometime hopefully soon is a video example of a scene’s original recording, followed by the same scene using vocal overdubs recorded in-studio. You’ll be able to hear that the dialogue stands out much more and gives you greater control over your background noise and sound effects.