Three basic types of microphones useful in a theatrical production are: lapel, hand-held, and area microphones.

The lapel (lavalier) and hand-held microphones provide the most freedom of movement and the least visual distraction when they are wireless. These microphones are very useful for individual reinforcement which is discussed later in this article.

Boundary microphones are a very good choice for area microphones because they have a low profile. Only unidirectional (favoring one direction) boundary micro­phones should be considered for purposes of theatrical reinforcement.

Depending on the width of the stage, two to four boundary microphones can be placed across the front of the stage. The best method for determining how many to use for a particular production is as follows:

2. Adjust the two microphones so that they split the stage in thirds (Figure 2).

Figure 2
Two Boundary Microphones

3. Increase the distance between the microphones until extreme stage left and right are adequately reinforced.

4. Now check to see if dialogue from front center stage is noticeably lower in level compared to dialogue from someone centered in front of one of the two microphones (make certain that both microphones are on). If the center stage is weak in level, then add a third microphone.

5. The third microphone should be placed at front center stage (Figure 3). The other two outside microphones should be moved away from the center microphone until you start to notice a weak spot in dialogue reinforcement.

Figure 3
Three Boundary Microphones

Place the microphones on the front lip of the stage. Determine which half of the microphone is least sensitive to sound. We'll refer to this as the back of the microphone. Make certain the back of the microphone is pointed toward any nearby sound sources you do not want reinforced such as audience noise or excess sound from the orchestra. Avoid pointing the front of any two boundary microphones toward each other. This will minimize the interaction of the two microphones (see Figure 4).

Figure 4
Microphone Interaction

Now that you have determined the quantity and location of the front stage area microphones, check to see how far upstage (toward the rear of the stage) you can move before the dialogue starts to fade. If the blocking requires any areas upstage beyond which the front area microphones "cover," additional area microphones will be needed. This may create a problem. Area microphones should not be located on the floor in traffic. A microphone that is inadvertently stepped on or bumped will make an annoying sound or may be damaged.

The lapel microphone's position must be thought through and placed carefully. You want the sound to be natural and to stay at a consistent level when the head is turned. This usually requires the lapel microphone to be positioned in the center of the chest. If the microphone is to be hidden, extreme care must be taken to minimize the "clothing" noise (which can result from the cloth rubbing on the microphone or even the cable).

Wireless maintenance is also important. Fresh, tested alkaline batteries should be used. Don't try to push the limit before they die. Many people use a new battery for every performance. Don't assume a newly purchased battery is good. It may be defective or have been on some shelf for years. In other words, test it!

As with any sound system, the gain or volume of microphones which are not in use should be turned down. This method of operation will give you more volume on the active microphones before feedback occurs. If you need all the gain you can get (which is usually the case), the sound person will need to be constantly riding the volume controls by adjusting up the active microphones and turning down the unused ones.