Microphone types and when to use which

An audience forgives a bad image; it does not forgive bad sound. A soft shot can be called style; a line you cannot understand is simply a mistake. Even so, sound gets the smallest share of the budget. Choosing the right microphone makes far more difference than buying expensive gear.

Distance matters more than anything

Whichever microphone you use the first rule is the same: get close to the source. As the mic moves away room reverb and ambient noise increase and the voice disappears into the room. Double the distance and the proportion of room sound grows noticeably.

A cheap microphone held near the mouth gives a better result than an expensive one three metres away.

Boom (shotgun) — natural, with a sense of place

A supercardioid shotgun is given from just outside the frame and above, on a boom pole. Aimed at the mouth it captures a sound that is both clear and natural; the actor's body and the room are audible, and the scene feels as though it takes place somewhere real.

Its weakness is that it demands control. It needs a boom operator, it has to follow the frame, and it is sensitive to wind and ceiling reflections. In enclosed, reverberant rooms the mic has to be angled slightly downward so it does not pick up the ceiling.

Lavalier — safe and consistent

Because a lavalier is fixed to the source the distance never changes; whether the actor turns or walks the level stays put. For interviews, corporate films and dialogue-heavy scenes it is the safest choice.

The cost is a sound with little character: the room is not heard and every line arrives at the same closeness. Clothing rustle and jewellery are the most frequent problems. Tape the cable to the body, have the actor take a few steps before you roll, and listen.

Use both at once

On professional sets boom and lavalier are recorded at the same time on separate channels. In the edit whichever is cleaner is used, and the two are blended when needed. This is not a luxury, it is insurance: when a problem you did not hear on set turns up in the edit, you have a second option.

The forgotten recording: room tone

In every location, once the shoot is over, record at least thirty seconds of silence with nobody speaking. This is called room tone. It is used in the edit to fill between lines, to clean noise and to hide cuts.

If you forget to give those thirty seconds on set, you will spend hours in the edit trying to fake them.