Recording dialogue stereo?
by reel2reel
on
Oct 28, 2007 at 8:27:21 pm
Hi,
Just wondering if anyone can offer an explanation of why it's best to record dialogue in mono as opposed to stereo? I've hunted high and low on the forum and can't find any reasons for why.
I'm guessing it's because you want to isolate the dialogue and keep it dead center?
Re: Recording dialogue stereo? by Carroll11 on Oct 31, 2007 at 5:49:25 am
James:
I am a 30 year, retired audio engineer.
Recording dialogue in stereo may sound like a cool idea, but unless the talent never moves an inch, the apparent "middle" of the sound image will move to the right and the left. Although this doesn't really violate any rules of recording, it's distracting to have the image of the main performer (or voice-over) moving around. But the real reason is that many times any recording, no matter what you want from it, will become mono for some reason. When it does, then you may have issues with apparent levels of the voice... seeming to fade in and out a bit. When it's exactly in both channels equally, it is rock steady in level, because it already is a mono portion of a stereo signal (if it has music with it). But if it's stereo and then becomes mono, then it can dissappear into the track, or worse... seemingly come and go as the performer moves around (as heard in mono). Part of this is phase shift, but mostly it's due to the "3db center rule" ... just an electrical thing that says that anything that is exactly in the center is 3db higher than if it were not... and when it moves off center, you risk having it go bye-bye in loudness for a second.
Listen to almost any pop music and you will hear that the underpinning instruments such as bass and kick drum are in the middle. It's for the same reason. The engineer doesn't want them to go up and down in level by themselves. it's kind of a promise that they will stay in the "sweet spot" of the core image. Lead vocals are often treated the same way for the same reasons.
In ads and documentaries, the dialogue is often backed up with stereo music, so it's "couched" in a track and important to remain at the same level. Recording it in mono will assure that. Recording in stereo risks that it won't stay the same. Add to that, sometimes compressors just don't know what to do with it, and will "pump" unevenly because of it. Then you will hear it move left and right disproportionately.
Now... after all that... try it anyway! Mono it and play with it. The real answer is to ignore all us tech guys and do what you like. Who knows, you might start a new pop trend!
Respectfully submitted,
LEE CARROLL - AES
PS: I retired 4 years ago. My last movie score was "The Usual Suspects" recorded at Studio West in San Diego. I'm on the crawl... somewhere... if you have good eyes.
Re: Recording dialogue stereo? by reel2reel on Oct 31, 2007 at 3:43:55 pm
Lee, thanks so much for that! I appreciate the excellent explanation. Although I've been familiar with the rule for a long time, it's nice to understand they 'why' of it.
I'm going to watch The Usual Suspects again just for the score and to see your name.
Re: Recording dialogue stereo? by Ty Ford on Oct 31, 2007 at 3:57:09 pm
Keeping audio mono lets you pan it in post if necessary.
Stereo dialog locks you in to a specific perspective unless you record in M/S (mid/side) and choose your spread in post.
Also, in XY stereo, you're not really pointing the mic at the talent. So you get a lot more ambient sound.
If the talent is still and the camera moves (with the mic attached) the listener can get a bit seasick from the perspective shift.
Regards,
Ty Ford
Ty Ford's "Audio Bootcamp Field Guide" was written for video people who want better audio. More at: http://home.comcast.net/~tyreeford/AudioBootcamp.html
or http://www.tyford.com
