Any microphone has a so-called polar pattern. This describes the change of the microphone output (electric voltage) when a sound source of constant loudness mover around the
microphone. This is a measure for the ability of the microphone to "hear" sound from various directions. An omnidirectional microphone pick up sound equally from any direction. The
polar patter is like a ball around the microphone meaning that is makes no difference in electric output from which direction the sound reaches the mic. The most common directional
microphone is the cardioid mic.

The pattern is somewhat shaped like a heart or kidney. Such a microphone has full sensitivity - or highest output - when sound reaches the front of the mic. From the sides (- or + 90
degrees) the mic has about half of the output and in the 180 degree direction it has a point of minimum output. That means that from the rear (usually the connector side) the mic is
almost deaf with an output of only about 1/10 to 1/30 of the front output. Such a microphone is used if suppression of environmental sound is required in respect to direct sound.

The hypercardioide has a slightly different pattern from the cardioide. It has a lower output at + or - 90 degrees and therefore has a more narrow angle of main sensitivity compared to
the cardioide. It does not have one point of minimum sensitivity but two at about + and - 140 degrees. Therefore the hypercardioid mic suppresses sound coming from both sides of
the rear direction. For this reason such microphones are preferred by singers on a stage because its usual to have monitor speakers at the sides of the singer.