Specifications

Balanced low-impedance output is preferred as usual.
Sensitivity can be moderate, due to the relatively close
placement of the microphone. The physical design is
optimized for body-worn use. This may be done by means
of a clip, a pin, or a neck cord. Small size is very desirable.
For a condenser, the necessary electronics are often
housed in a separate small pack, also capable of being
worn or placed in a pocket. Some condensers incorporate
the electronics directly into the microphone connector.
Provision must also be made for attaching or routing the
cable to minimize interference with movement. Wireless
versions simplify this task.
Placement of lavalier microphones should be as close
to the mouth as is practical, usually a few inches below the
neckline on a lapel, a tie, or a lanyard, or at the neckline in
the case of a woman’s dress. Omnidirectional types may be
oriented in any convenient way, but a unidirectional type
must be aimed in the direction of the mouth.
Avoid placing the microphone underneath layers
of clothing or in a location where clothing or other objects
may touch or rub against it. This is especially critical
with unidirectional types. Locate and attach the cable to
minimize pull on the microphone and to allow walking
without stepping or tripping on it. A wireless lavalier system
eliminates this problem and provides complete freedom
of movement. Again, use only high quality cables, and
provide phantom power if required.
Audience
The desired sound
source is a group of talkers.
Undesired sound sources
may include loudspeakers
and various ambient
sounds.
The use of audience
microphones is governed,
to some extent, by the
intended destination of the
sound. In general, high
level sound reinforcement
of the audience in a
meeting facility is not
recommended. In fact, it is
impossible in most cases,
unless the audience itself
is acoustically isolated
from the sound system
loudspeakers. Use of audience microphones to cover the
same acoustic space as the sound system loudspeakers
results in severe limitations on gain before feedback.
The absolute best that can be done in this circumstance
is very low level reinforcement in the immediate audience
area, and medium level reinforcement to distant areas,
such as balconies or foyers. Destinations such as isolated
listening areas, recording equipment, or broadcast
audiences, can receive higher levels because feedback is
not a factor in these locations.
A condenser is the type of microphone most often
used for audience applications. They are generally more
capable of flat, wide-range frequency response. The most
appropriate directional type is a unidirectional pattern,
usually a cardioid. A supercardioid or a hypercardioid
may be used for slightly greater ambient sound
rejection. Balanced low-impedance output must be used
exclusively and the sensitivity should be high because of
the greater distance between the source and the
microphone. This higher sensitivity is also easier to obtain
with a condenser design.
The physical design of a microphone for audience
pickup should lend itself to some form of overhead
mounting, typically hanging. It may be supported by its
own cable or by some other mounting method. Finally,
it may be a full size microphone, or a miniature type for
unobtrusive placement.
32
MEETING FACILITIES
Audio Systems Guide for
Good technique for use of lavalier
microphones includes:
• Do observe proper placement and
orientation.
• Do use pop filter if needed, especially
with unidirectional.
• Don’t breathe on or touch microphone
or its cable.
• Don’t turn head away from microphone.
• Do mute lavalier mic when using
lectern or table microphone.
• Do speak in a clear and distinct voice.
Audience mic