Microphone Polar Pattern Diagrams: How to Read Them Properly

Every microphone responds differently to sound arriving from various directions around its capsule. The polar pattern diagram maps this directional sensitivity as a visual chart showing where the mic picks up audio clearly and where it naturally rejects sound. Understanding these diagrams transforms how you position mics and solve acoustic problems in any recording environment.

This guide breaks down the three main polar patterns found in professional microphones, explains how to interpret the technical diagrams correctly, and demonstrates practical applications using real microphones from Audio-Technica, Shure, Rode, and other manufacturers. We cover frequency response variations across different angles, off-axis rejection characteristics, and common placement mistakes that compromise recordings.

Understanding Basic Polar Pattern Shapes

The most fundamental polar pattern is cardioid, named for its heart-like shape when viewed from above. A Shure SM58 exemplifies this pattern perfectly, with maximum sensitivity directly in front of the capsule at zero degrees and significant rejection at 180 degrees behind the mic. The diagram shows this as a rounded bulge facing forward and a sharp indent at the rear. This design makes cardioid mics ideal for isolating individual sound sources while minimising background noise and feedback in live situations.

Omnidirectional patterns appear as perfect circles in polar diagrams, indicating equal sensitivity in all horizontal directions around the microphone. The Audio-Technica AT4049b demonstrates this pattern beautifully, capturing sound with consistent frequency response whether the source sits directly in front, to either side, or behind the capsule. These mics excel in controlled acoustic environments where you want to capture the natural ambience of a room or record multiple performers arranged around a single microphone.

Figure-8 or bidirectional patterns create two opposing lobes of sensitivity with complete nulls at 90 and 270 degrees on either side. The Royer R-121 ribbon microphone showcases this pattern distinctively, picking up sound equally from front and rear while rejecting audio from the sides entirely. This makes figure-8 mics invaluable for mid-side stereo recording techniques or isolating two performers facing each other across the microphone.

Reading Frequency Response Variations

Professional microphone specifications include multiple polar pattern diagrams showing how directional characteristics change across different frequency ranges. The Neumann U87Ai documentation provides excellent examples of this, with separate diagrams for 125Hz, 500Hz, 1kHz, 4kHz, and 8kHz. At lower frequencies around 125Hz, the cardioid pattern becomes less directional and approaches omnidirectional behaviour. This explains why bass frequencies from nearby sources can bleed into your recording even when positioned behind the microphone.

Higher frequencies above 4kHz typically show tighter, more focused patterns with sharper rejection angles. The Rode Procaster demonstrates this clearly in its specifications, where the cardioid pattern becomes increasingly narrow as frequency rises. This frequency-dependent directionality affects how you position mics relative to cymbals, sibilant vocals, or other high-frequency sources that might create harsh off-axis coloration.

Some manufacturers provide three-dimensional polar plots that show both horizontal and vertical directional characteristics. The Electro-Voice RE20 includes these comprehensive diagrams, revealing how the microphone responds to sound sources positioned above or below the capsule axis. Understanding these vertical patterns prevents common mistakes like positioning a boom mic too high above a vocalist, where frequency response changes can create thin or nasal tonality.

Proximity Effect and Pattern Interaction

Directional microphones exhibit proximity effect, where bass frequencies increase dramatically as sound sources move closer to the capsule. This phenomenon does not appear in polar pattern diagrams but interacts significantly with directional characteristics. A Shure Beta 57 shows strong proximity effect when vocals are within six inches, but this bass boost only occurs for sounds arriving from within the cardioid pickup pattern. Sources positioned in the rejection zones do not trigger proximity effect even at close distances.

The interaction between polar patterns and proximity effect becomes crucial for recording techniques like close-miking drum toms or guitar amplifiers. An Audio-Technica AT4040 positioned three inches from a guitar speaker will emphasise low frequencies significantly, but rotating the mic 45 degrees off-axis reduces both the desired signal and the proximity effect proportionally. Understanding this relationship helps balance tone shaping with proper microphone placement.

Omnidirectional microphones like the DPA 4006A do not exhibit proximity effect regardless of source distance, making them more predictable for consistent tonal balance. However, this also means you cannot use proximity effect creatively to enhance bass response for thin-sounding sources. The polar pattern choice directly impacts your available tone-shaping options during recording.

Practical Applications and Microphone Selection

Recording acoustic guitar requires understanding how polar patterns capture both direct sound from the instrument and reflected sound from surrounding surfaces. A cardioid pattern like the Neumann KM184 focuses on the guitar body while rejecting reflections from the rear wall, creating an intimate, controlled sound. Switching to an omnidirectional pattern with the same microphone capsule system captures more room ambience and natural reverb, suitable for spacious, atmospheric recordings.

Drum recording demonstrates polar pattern selection clearly through overhead microphone choices. Cardioid overheads like a matched pair of AKG C414s focus primarily on cymbals and drum attacks while minimising bleed from nearby instruments. Omnidirectional overheads such as Schoeps CMC6 systems capture the complete drum kit with natural balance but require excellent room acoustics and careful isolation from other instruments.

Vocal recording in untreated rooms benefits from tight cardioid patterns that reject wall reflections and air conditioning noise. The Shure SM7B provides exceptional rear rejection, allowing vocalists to perform in less-than-ideal acoustic environments. Conversely, vocal recording in professionally designed vocal booths can utilise wider patterns or even omnidirectional mics like the Neumann TLM103 set to omni mode for more natural, open vocal tones.

Conclusion

Microphone polar pattern diagrams provide the roadmap for achieving professional recordings through intelligent microphone placement. Master these visual guides to control what your microphones hear and reject, transforming challenging acoustic situations into opportunities for creative sound capture. The difference between amateur and professional recordings often comes down to understanding these fundamental directional characteristics.