A microphone that picks up sound from the front of the unit. Also called a "unidirectional" mic, the term cardiod comes from "kardia," which means heart in Greek. The cardoid mic pattern loosely resembles the shape of a heart.
Bidirectional, Omnidirectional and Stereo
"Bidirectional" mics pick up sound from both front and rear. "Omnidirectional" pick up in a 360 degree circle. "Stereo" mics pick up from the front but cover a wider area when two or more people are speaking side-by-side. See microphone
Cardiod Sensitivity and Selection
Cardiod mics are the best when one person is speaking as sounds from the side and rear are mostly ignored. The Gain control on this Yeti mic (bottom) can be switched starting from left to right from stereo, omnidirectional, cardiod and bidirectional.