Patti Smith singing into a Shure SM58

A microphone’s directionality or polar pattern indicates how sensitive it is to sounds arriving at different angles about its central axis. The polar patterns illustrated below represent the area around the microphone that produces the same signal level output if a given sound pressure level (SPL) is generated from that point. How the physical body of the microphone is oriented relative to the diagrams depends on the microphone design. For large-membrane microphones such as the Audio Technica AT4040, the upward direction in the polar diagram is usually perpendicular to the microphone body, commonly known as “side fire” or “side address”. For small diaphragm microphones such as the Shure SM58, it usually extends from the axis of the microphone commonly known as “end fire” or “top/end address”.

Some microphone designs combine several principles in creating the desired polar pattern. This ranges from shielding (meaning diffraction/dissipation/absorption) by the housing itself to electronically combining dual membranes.

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