Omnidirectional microphones have an omnidirectional polar pattern and pick up sound pressure from all directions with equal sensitivity. They are therefore omnidirectional, in contrast to directional microphones, which have a lobe-shaped polar pattern.
Omnidirectional microphones are concerned only with directionality, not with microphone technology. Omnidirectional microphones receive scanning pressure from all directions with equal sensitivity. The degree of focusing is 1. The omnidirectional pattern is used for recording larger sound sources such as choirs and orchestras.
Omnidirectional microphones are condenser microphones or electret microphones that are primarily clip-on microphones used in studios or on stages. Since omnidirectional microphones pick up sound from all directions, there is a risk of acoustic feedback, which causes an unpleasant whistling sound. An advantage is that omnidirectional microphones have no proximity effect.