What are Cardioid Microphones?
Cardioid Microphones are microphones that pick up sounds with high gain from the front and sides but poorly from the rear. Cardioid microphones are named for the fact that their directional sound pick-up is roughly heart-shaped in nature.
The image to the right shows a typical polar plot response of a cardioid microphone. Polar plots show the gain of a microphone for all the various directions that it points to in relation a fixed sound source. The sound source stays in the same position but the microphone is rotated around from 0° to 360°. By doing this test, we can know what gain the microphone records at all of the various directions that it points. A cardioid microphone basically has a polar plot response that is heart-shaped in nature. It picks up sound with high gain, or sensitivity, from the front and sides, but steeply lower when sounds are from the rear.
Cardioid microphones are used in applications where sound needs to be picked up from the front and sides but not the rear. An example of this may be musical performance where a singer may be singing in the front, a band playing instruments on the sides, with an audience of viewers in the back. In a scenario, it may be desired only to record the music, the singer in front and band on the sides, but not the audience in the rear. For this type of scenario, cardioid microphones have great use and applicaton.