Tuesday, September 13, 2011

Can You Hang a Lav Mic?



I'm a little late on this one (Dave posted it last week), but it's still a good video and worth noting. This time Knoptop takes Quick FX in an audio direction, testing the theory that you can hang an inexpensive lav mic and get better sound than the normal position on clothing. He gets this from the stage, where actors typically get the ol' "mic on the forehead" trick which Dave sort of replicates here.

It's an interesting experiment, but I think this proves that below the mouth is still the best position for a lav. Actually, I think it sounds better mostly because it's closer to the mouth than the hung version. Even when hidden under the hairline, the mic has less distance to the mouth then when suspended just above the frame. That's one "secret" of good audio. Get the mic as close to the speaker's mouth as possible, no matter where the mic may be.

3 comments:

Harpo said...

A few observations on your video:
When I'm explaining how to do sound to someone who has no experience, I explain 3 things. The most important factors in sound are (in order): how close the microphone is to the subject, what type of microphone you use (lav, shotgun, dynamic, condenser, etc) and quality of that microphone. For the sake of brevity, I'll just go into details about the first one, since it's by far the most important.

In film, it's often a major goal to not see the mic in the shot. As such, it generally gets pushed behind everything else on the priority list, especially since it's very difficult to check until you get back to the editing room. Pictures can be seen instantly on the screen and cheap headphones tell you "Yes, I can hear it," but "I can hear it" does not mean the sound is good.

As you mentioned, professional theater sound engineers usually place the mic directly below the wig on the forehead because very close to the mouth and allows them to turn their heads freely without changing that fundamental relationship (also, the quick costume changes that are frequent in theater mean clothing placement would be impractical).

Notice in your video whenever you turn your head the sound changes and gets weaker; that's a simple demonstration of this principal, and it's something filmmakers have been struggling with since the dawn of sound. http://www.youtube.com/watch?v=OTFCctdiS04

Placing a lav on someone's chest gets a pretty good sound with minimal effort, especially if movement of the subject is required. This frequently wins over having an expensive shotgun mic with a dedicated operator (and preferably a dedicated mixer as well) even though it would sound much better.

Your observation that chest-placement delivers more bass tones is entirely correct. Your chest is a giant resonating chamber for the voice and a microphone near there will certainly pick it up.

As an audio professional, sound is a big pet peeve for me. Very few low/no-budget productions treat it with the proper respect I believe it deserves. Obviously, it's not as important as the pictures or storytelling, but that's the technical battle of making films: finding the right balance between good and good enough.

-Harpo
http://dellarteproductions.com/

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DIYFilmSchool.net said...

I think it's pretty apparent that clipping a lapel mic to a lapel will yield the best results, for the various reasons Harp mentioned.

Obviously, the test wasn't necessarily to see that hanging a lapel mic is a better option but rather to see how it would perform AS an option.

As soon as Knoptop hung the lapel, I was turned off. All the dynamics were basically removed. It was still clear, but the sound itself was rather hollow.

Thanks for posting this though; it satisfied my curiosity.

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