1. Overhead boom.
  2. Boom from underneath.
  3. Boom mics as plant mics.
  4. Lavalier mics as plant mics.
  5. Lavalier mics as body mics.
  6. Lavalier mics, as wireless or radio mics.

3) If the overhead microphone does not have to move, does it make any acoustical difference whether the mic is held up by human hands with a fishpole or rigged to a C-stand or clamp?

The definition of a plant mic is any mic fixed in place on a set. It can be a boom mic secured by any imaginative or convenient means over a dialogue mark. Or it can be a boom mic secured in an "underneath" position, such as behind a table or potted tree. Or it can be a miniature lavalier strategically attached or hidden anywhere in the set.

Which type of plant mic you choose depends on the situation you are faced with.

Let's say you are covering dialogue of two actors in a room and a third actor pokes his head into a doorway and delivers a line. Your two key actors are probably being covered by a handheld fishpole. The doorway could be easily miked either by a boom mic positioned above the door arch with a clamp or C-stand. 4) Another choice could be a lavalier as a plant mic, taped to the inside of the door frame.

A telephone booth can be readily miked by hiding a lavalier onto the surface where the caller will be facing.

A desktop can be miked by hiding a lavalier on a pen set or a rollidex. A restaurant table can be miked by sticking a mic into the floral centerpiece. (Okay, cue the "plant" mic puns.)

To mic an automobile, merely attach a lavalier to the sun visor. Determine to which side the actor/driver will be speaking, and cheat the position of the plant mic to accommodate that.

A microphone on the visor is preferable to using a mic on the actor's body. A body mic would give you lots of clothing rustle, seat belt rubbing, and other noise. On the visor, it is completely clean. Being high up in the vehicle, the mic is distant from road noise (gravel striking the underbelly of the car), as well as less susceptible to engine rumble. The padded ceiling of the vehicle reduces sound reflections and echo, and the padding of the visor provides additional isolation.

To cover driver and passenger, put the mic on the visor near the center of the car. If the passenger has a much weaker voice than the driver, place the mic on the center-facing edge of the passenger's visor. Or, if the driver faces forward most of the time, but also has a line or two directed out of his window, cheat the position of the mic to the far left of this visor. If necessary, use two plant mics to cover driver's window, driver front, passenger front, and passenger window. A second or third mic can be used to cover dialogue from the rear seat.

Be imaginative in your mic placement, but don't overdo it. Let one mic do as much work as possible; multiple mics in close proximity to each other will interfere with each other, creating echo and a tinny sound.

One caution about planting mics around on the set. They will only be effective if the dialogue is directed in their general direction. A plant mic that is behind someone's head won't be much good. Also, their range is limited; don't expect miracles. This is filmmaking, not surveillance. What works fine for a stake-out may not be acceptable in a professional sound mix.