A cardioid microphone is designed to have the most sensitivity in front and the least sensitivity at the back. A cardioid microphone is very efficient in isolating unwanted ambient sound and focus on the main source – this is suitable for loud stages.
Unlike the cardioid microphone, however, the supercardioid is able to pick up some sound directly at the back. With supercardioids, monitor speakers must be placed correctly to avoid collecting feedback.
An omnidirectional microphone or ‘Omni’ is able to capture sound from any angle – this is because Omnis have equal sensitivity at every angle.
A microphone with omnidirectional polar pattern does not have to be positioned or directed a certain way to capture sound because it is designed to capture both the direct feed and the ambient sound thus making it very helpful especially in the case of lavalier microphones.