Specifications

Omnidirectional pattern
Unidirectional pattern
The selection of a flat or shaped response microphone
involves consideration of both the sound source and the
sound destination. The frequency range of the microphone
must be wide enough to pick up the desired range of the
sound source. This range must also be appropriate to the
intended destination of the sound: that is, wider range for high
quality sound systems or recording/broadcast systems,
narrower range for speech-only public address systems.
Within its range the microphone should respond in
such a way that the sound is reproduced either with no
change (flat response) or with changes that enhance the
sound in some desirable manner (shaped response).
Normally, microphones with flat, wide range response are
most useful for music applications.
For speech use, the most common response is
shaped. Typically, this consists of limiting the range to that
of the human voice and adding an upper midrange
response rise. Such a presence rise, coupled with
controlled low and high frequency response can provide a
sound with improved vocal clarity. This is especially true for
lapel or lavalier microphones.
Finally, the frequency response of some microphones
is switch adjustable to tailor the microphone to different
applications. The most common are a low frequency rolloff
switch, which can help prevent “rumble”, and a presence
rise switch to enhance intelligibility.
3) Directionality: How does the microphone
respond to sound from different directions?
The directional characteristic of a microphone is
defined as the variation of its output when it is oriented
at different angles to the direction of the sound source. It
determines how best to place the microphone, relative to
the sound source(s), to enhance pickup of desired sound,
and to minimize pickup of undesired sound. The polar
pattern of a microphone is the graphical representation of
its directionality. The two most common directional types
are omnidirectional and unidirectional.
A microphone that exhibits the same output
regardless of its orientation to the sound source will show
on a polar graph as a smooth circle and is said to have an
omnidirectional pattern. This indicates that the microphone
is equally sensitive to sound coming from all directions.
An omnidirectional microphone can therefore respond to
sound from a wide area, but cannot be “aimed” to favor
one sound over another.
A unidirectional microphone, on the other hand, is
most sensitive to sound coming from only one direction.
On a polar graph, this will appear as a rounded but non-
circular figure. The most common type of unidirectional
microphone is called a cardioid (like cardiac), because of
its heart-shaped polar pattern.
11
MEETING FACILITIES
Audio Systems Guide for