Samson CM15P - Manual (Page 8)

CM15P and CM20P Polar Pattern
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Every microphone has a characteristic polar pattern that determines how well it accepts or rejects signal coming from
various areas around the microphone. For example, omnidirectional mics accept all signals regardless of where those
signals originate (in front of the mic, behind it, to the side, etc.).
In contrast, directional cardioid mics are specifically designed to accept mostly signal coming from directly in front,
and to reject signal coming from behind or from the side. The cardioid pattern is utilized by the CM15P and CM20P (as
shown in the illustration below). For this reason, the CM15P and CM20P excel in envi-
ronments where there is a good deal of unwanted ambient sound—it delivers those
signals originating directly in front of the mic capsule itself while rejecting those that
originate from behind.
The polar pattern also determines how prone a particular mic is to inducing feedback.
Feedback is that characteristic nasty howling sound that occurs when a mic is placed
too close to a loudspeaker—the signal from the loudspeaker is fed into the mic, then
into the loudspeaker, then into the mic, over and over again until an oscillating tone
is generated. Because the cardioid pattern utilized by the CM15P and CM20P is so
good at rejecting signal coming from the rear of the mic, you’ll find that use of the
CM15P and CM20P greatly minimizes feedback problems.