In contrast to an actual character with dialogue, the voice-over is a production technique that uses an off-screen voice that is not part of a story. Whereas, the use of verbal commentary of the actual story to the audience is known as narration. This will be provided by one of the main characters or a disembodied third-person voice.
Difference in Process
Because you want different sorts of sounds for different expressions, the biggest difference in approach with voice-over vs narration will be visible in your mic location.
To take advantage of the proximity effect in a voice-over for a radio commercial, for example, the actor will need to be close to the mic. In this situation, the voice-role over’s is more like to that of an announcer, thus you’ll want to generate a sense of strength or God-like sound. You’ll also want to employ ducking software, which reduces all sounds save the speech. As a result, the voice will stick out and become a strong focal point.
In contrast, you want the voices in an 3D or animated film to seem truer and more lifelike so that the conversation sounds more natural. The audience must believe that the characters are real and conversing with one another, thus any effect that detracts from that illusion or sticks out in any way should be avoided. The voice and visuals must blend together as much as feasible. To get this look, you’ll need a few mic placements, which will be decided by the environment in which you’re working.
When recording the natural-sounding conversation for a film, a decent quality mic on a stand about half a metre above the actor with a boom microphone facing them at a 45-degree angle towards their chest would be used. This will undoubtedly help in the creation of a more natural sound. This eliminates the desired proximity effect while recording voice-overs, and the radiation pattern of the voice will not be captured as clearly as when the mic is immediately in front of the actor’s mouth. This will also add some early reflections and distance, so be sure the room you choose to record in produces the sound you want.
More on Microphone placement
You want a little space between the motion and the character voice to make it sound more realistic. This necessitates the use of a great room. To avoid plosives, I like a fairly acute angle. I hate having to redo a take for technical reasons. However, if the actor/actress is inexperienced or does not have a good ear in general, they will frequently have their entire head shifted down at the stand rather than just gazing down or using clips to shift their paper up.
If we’re talking about a radio commercial, I’ll often move closer and lower the angle. That proximity is required for movie trailer voice of God and loud radio announcer stuff. However, if the radio spot has actual characters rather than just an announcer, I’ll give it some more animation-like distance.
For safety considerations, I always use a compressor when doing voiceover. I’m not afraid to turn up the ratio on the radio because it’ll just get broken afterwards.