When possible, use only one microphone
to record dialogue.
When two or more microphones are
used, they should be approximately 10 feet
apart.
Alertness and proper respect for the sensi-
tivity of the microphone are essential when you
are recording interviews and presentations.
When recording presentations of participants
who are seated around a table, you may place
the microphone on the table near the center of
the group. If all those present have an oppor-
tunity to enter into the discussion, be sure that
you select an omnidirectional microphone to
pick up speech waves from all directions. If a
directional microphone is used, it must be
handed around or the voices of some of the par-
ticipants will not be recorded.
When confronted with a microphone, some
people become nervous and begin tapping the
table or making some other noise, which will be
recorded. If the noise takes place when someone
is speaking, it cannot be edited out. Therefore,
individuals present should be reminded that they
must keep unnecessary noises to a minimum.
To record the narration of one person, a
lavaliere-type microphone attached with a cord
around the person’s neck provides excellent
results. This permits the individual to forget
about the microphone, talk freely, and move
about.
In placing microphones, you will at first have
to depend upon your own hearing. But you must
realize that the sound heard by your ears is dif-
ferent from that “heard” by a microphone.
People possess the ability to concentrate their
attention on a person who is speaking; though
the room is filled with other people, they
disregard extraneous sound. The microphone,
on the other hand, has but one ear and that ear
does not have the ability to reject unwanted
sounds. Every sound that reaches the micro-
phone is picked up. In placing the microphone,
move it around to various locations and listen
with one ear. In this way you will hear much the
same as the microphone does. Thus, you will be
able to judge what the microphone will “hear”
and place it in the best position.
Amplifiers
After the microphone, the next link in the
chain that makes up an audio system is the
amplifier. After the sound is received by the
microphone, it is fed into the amplifier. The
amplifier receives this weak signal and boosts it
until it can be heard with the aid of a
loudspeaker. However, amplifiers are not
necessarily separate units nor do they need a
microphone. A motion picture projector has a
built-in amplifier for its sound system. A tape
recorder may also have a built-in amplifier.
Usually, separate amplifiers are found in a
public address system or in a recording studio
where multiple microphones are used.
After sound is converted into electrical
energy and amplified, a device must be used to
convert this energy back into sound. This device
is the loudspeaker.
Loudspeakers
The loudspeaker, or speaker, converts elec-
trical current variations into sound. Although
various types of speakers have been developed
and used at different times, the majority of
those currently in use are permanent magnet
dynamic speakers with impedance values be-
tween 3.2 and 16 ohms. They require only a two-
wire connection to the amplifier.
The placement of the loudspeakers is largely
determined by the type of presentation to be
given. For example, when used with a motion
picture projector, the speaker should be placed
near the screen so that the sound and picture will
come from the same direction. The placement of
the loudspeaker in other situations should be
given as much consideration as the placement of
the microphone. The loudspeaker should face
away from the reflecting surfaces, such as large
tabletops and bare walls. Also, speakers should
not be placed facing each other, facing large flat
surfaces, or facing the microphone, because
acoustic interference is certain to result. Single
speakers or small groups of speakers should be
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