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How to Select the Right Audio Mics

I’ve been listening to the Digital Production Buzz for a good part of the last year. It’s a weekly podcast hosted by Larry Jordan, a Final Cut Pro guru of sorts. One of the more useful segments I heard was broadcast on December 3rd as part of his Government Video Expo special report. It was an interview with Steve Savanyu, Director of Educational Services for Audio Tecnica. Steve was able to explain very succinctly the process of picking the best microphone, and how to position it. It’s basic stuff, but sound not being one of my personal strengths, I jotted down some notes for myself, to reinforce what I heard. All the tips are based on a simple mic’ing scenario of recording people standing in front of a camera.

Listen to the podcast here. Select “2nd Guest” from the bottom right, labeled “What’s the Buzz”.

Overview

  • Based on the fundamental hierarchy of microphone technique, the first choice is always a shotgun mic, on a boom pole, with a good boom operator:
    • Boom from above first
    • Boom from  below second
    • If booming is not possible (due to distance or logistics of the shot), a lav mic would be your third choice
  • Mounting mics on the camera might make sense for a run & gun shoot, or in cases where all you want to do is record the ambient voices filling a room. But in general, they will pick up a lot more than what you want and likely won’t get you as close to the talker as possible.

Lavalier Mics

Omni-Directional Lavalier (Condensers)

  • Pros
    • Good for mic’ing talent that isn’t well versed with talking into a mic, which is usually the case. It can pick up sound despite talent turning their head side to side on camera.
  • Cons
    • Tend to pick up a lot of ambient sound in the room
    • Have a very limited bass response, so it’s difficult to make the voice sound really warm, although this can be improved by lav placement.

Directional Lavaliers (Cardioids)

  • Pros
    • Good in cases where talent understands how to use a mic
    • Minimizes pick-up of undesired background sounds
    • Proximity effect, which means the closer you are to the mic, the more low end response it will give you. It picks up more chest resonance, which is why radio hosts get up real close to their mics, in order to get that big, deep sound to their voice.
  • Cons
    • You do have to instruct the talker that if they move their head, they have to move their head and chest in the same plane, in order to keep the head aligned with the mic.

Positioning

  • To avoid rustling on the talent’s clothes, tricks of the trade professional audio guys use are mole skin, tape triangles, and using fabric softener or water.
  • For big dangly jewelry or long hair, you can put the lav high up on a person’s collar and instruct the talent not to move their head much.

Shotgun Mics

General Info

  • Short shotguns are 6-8″ long and picks up about a 5 degree pattern in front of the mic.
  • A long shotgun is up to 18-24″ long and has a very narrow pattern – about a 1 degree pickup.

Pros

  • Delivers less room noise, tighter talent sound, and better sound overall relative to a lavalier

Cons

  • Requires a good boom operator paying attention to where the mic is pointing.

Booming

Positioning

  • You want the mic as close to the sound source as possible. If you’re a budding camera guy, the thing to remember is a shotgun mic is not like a zoom lens. It can’t bring the sound closer to you, so if it’s positioned 10′ away, it’s going to sound 10′ away.
  • Always use, as a minimum, a foam windscreen, even indoors. The foam windscreen outdoors is not always effective, but indoors, it’s going to minimize the pick up of slight air movement from air handling systems, breezes coming in from an open window, etc.
  • To position, take a little strip of first aid tape, maybe a quarter inch wide, and put it around the tip of the windscreen. During rehearsal, dip the mic well into the shot to get an in/out mark from the cameraman, then use something in the room as a reference point for keeping the mic out of the frame, and as close to the subject as possible.

Directionality

  • Booming from above is the first choice because your voice travels up your face. That’s why in theatre, the best place to hide a lav mic is at the forehead of the hairline. Also, since the talent is usually standing on carpet or grass, and you’re booming from above, you’re less likely to pick up undesired background sounds. Lastly, booming from above is the most comfortable position to hold the boom pole.
  • Booming from below is the 2nd position. It will pick more low end response because it’s going to pick up more chest sound. This is what you should do if you can’t get in from above due to a low ceiling, lighting in the way, boom shadows, etc.

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