Microphone Polar Patterns: Cardioid, Figure-8 & Omni Acoustic Rejection

A microphone's polar pattern describes its sensitivity to acoustic sound waves arriving from different directional angles around its capsule.

The Primary Polar Patterns

• Omnidirectional: Pure pressure transducer. Equally sensitive to sound from all 360 degrees. Exhibits zero proximity effect and resists wind noise.
• Figure-8 (Bidirectional): Pure pressure-gradient transducer. Highly sensitive to sound from front (\(0^\circ\)) and rear (\(180^\circ\)), with absolute acoustic null cancellation at the sides (\(90^\circ\) and \(270^\circ\)).
• Cardioid: Created by combining equal parts omnidirectional and figure-8 response. Maximum sensitivity at \(0^\circ\), with a deep rejection null at the dead rear (\(180^\circ\)).
• Supercardioid & Hypercardioid: Narrower frontal pickup with maximum rejection null angles around \(126^\circ\) and \(110^\circ\), paired with a small rear sensitivity lobe.

The Acoustic Proximity Effect

Any directional microphone utilizing pressure-gradient capsules exhibits the proximity effect: a dramatic acoustic boost in low frequencies as the sound source moves closer than 30 cm to the diaphragm.