Polar patterns define what a microphone hears from different directions, and they're the most underutilized tool in most engineers' recording arsenals. I've watched engineers spend hours EQing bleed out of a drum overhead recording when simply switching from omnidirectional to cardioid on the microphone would have eliminated the problem at the source. Polar pattern selection is the first stage of signal processing, and it happens before any electronics get involved.

A microphone's polar pattern is determined by how the diaphragm is exposed to sound pressure. Pressure microphones expose only the front of the diaphragm and produce an omnidirectional pattern. Pressure-gradient microphones expose both front and back, and the acoustic path length difference between the two sides creates directionality. The specific pattern -- cardioid, supercardioid, figure-8, or anything in between -- depends on the acoustic design and, in multi-pattern microphones, on how the signals from multiple capsules are combined electronically.

Omnidirectional: The Most Natural but Least Practical

An omnidirectional microphone picks up sound equally from all directions. The polar pattern is a perfect circle (in theory), and because it's a pressure microphone with no rear ports, it has no proximity effect -- bass doesn't increase as you get closer to the source. The frequency response remains consistent regardless of distance or angle.

The trade-off is obvious: no rear rejection. In a room with any audible reflection or competing sound source, the omni microphone captures all of it. This makes omnidirectional microphones impractical for most home studio recording, where room acoustics are rarely good enough to sound natural when captured without directional filtering.

Where omnidirectional microphones excel is in acoustic environments that are genuinely good -- concert halls, live rooms with proper treatment, and outdoor recordings. The DPA 4006 at approximately $2,300 is the standard for classical recording because its omni pattern captures the room's natural reverberation without the coloration that directional patterns introduce. In a well-designed recording space, the omni microphone produces the most realistic sound of any pattern.

The Proximity Effect Advantage

Wait -- omnidirectional microphones have no proximity effect. That's actually an advantage in situations where the performer moves relative to the microphone. A vocalist who leans in and pulls back will maintain consistent tonal balance with an omni mic, whereas a cardioid mic will shift between thin (far) and bass-heavy (close). For documentary-style interviews, field recording, and any situation where the subject isn't trained to maintain a constant distance, the omni pattern is more forgiving.

Cardioid: The Workhorse Pattern

Cardioid microphones reject sound from the rear (180 degrees) and are most sensitive at the front (0 degrees). The pattern is shaped like a heart -- hence the name. Real-world rear rejection is typically 15-25dB at frequencies below 1kHz, decreasing to 5-10dB above 5kHz where the wavelength becomes small enough to diffract around the microphone body.

The proximity effect on a cardioid microphone boosts low frequencies by 6-12dB when the source is within 15cm of the diaphragm. On vocals, this boost adds warmth and presence. On acoustic guitar, it can make the instrument sound muddy if the microphone is too close. Understanding and controlling proximity effect is the difference between a cardioid microphone sounding great and sounding boomy.

The cardioid pattern is created in dual-diaphragm condensers by combining the signals from front-facing and rear-facing capsule halves. In the Neumann U87, the cardioid pattern uses 50% of the front capsule signal and 50% of the rear capsule signal (inverted). This combination produces the classic heart-shaped pattern with approximately 20dB of rear rejection at 1kHz.

Supercardioid and Hypercardioid: Narrower Pickup, Side Lobes

Supercardioid and hypercardioid patterns offer progressively narrower front pickup angles and greater rear rejection, but at a cost: they develop sensitivity lobes at the sides. A supercardioid microphone has null points (minimum sensitivity) at approximately 127 degrees off-axis, with side lobes at 110 degrees where sensitivity is about -10dB relative to the front. A hypercardioid microphone pushes the null points to 110 degrees and increases the side lobe to about -6dB.

This matters in live sound and multi-mic drum recording. A hypercardioid snare microphone rejects the hi-hat (positioned to the side) better than a cardioid mic would, but it picks up the floor tom if that's positioned in the side lobe. Understanding where the null points and side lobes are -- and positioning other sound sources accordingly -- is the practical skill that separates an experienced engineer from someone who just points mics at things.

The Electro-Voice RE20, a hypercardioid dynamic microphone, became the broadcast industry standard partly because its Variable-D technology maintains consistent frequency response regardless of distance, and its hypercardioid pattern rejects studio noise from behind and the sides while capturing the announcer's voice cleanly from the front.

"I can solve more problems with polar pattern selection than with EQ. If the room sounds bad, I go tighter. If the room sounds good, I go wider. It's that simple." -- Sylvia Massy, Recording Engineer, 2019

Figure-8 (Bidirectional): The Ribbon Microphone Pattern

Figure-8 microphones pick up sound equally from the front and back, with null points at the sides (90 and 270 degrees). All true ribbon microphones are naturally figure-8 because the ribbon element is exposed on both sides and responds to the pressure gradient between them. Figure-8 patterns are also available on some dual-diaphragm condensers by combining the front and rear capsule signals with the same polarity.

The figure-8 pattern is the foundation of Blumlein stereo recording (two figure-8 microphones at 90 degrees to each other) and Mid-Side recording (one cardioid facing forward plus one figure-8 facing sideways). Both techniques produce stereo images with excellent mono compatibility and accurate spatial reproduction.

The null points at 90 degrees are where the figure-8 pattern becomes powerful. In a drum overhead configuration with two figure-8 microphones in Blumlein, the snare drum (centered between the mics) hits the null points and is captured at equal level in both channels, creating a solid center image. The cymbals, positioned to the sides, fall into the pickup lobes and create a wide stereo spread.

Multi-Pattern Microphones: Flexibility vs Consistency

Multi-pattern condensers like the AKG C414 (9 patterns) and the Neumann U87 (3 patterns) use a dual-diaphragm capsule and switch the electrical connection between the front and rear diaphragm halves to produce different patterns. The patterns available typically include omni, cardioid, hypercardioid, and figure-8, with several intermediate settings.

There's a caveat: the frequency response changes with each pattern. The U87's omnidirectional response is flatter than its cardioid response, which has a deliberate presence peak. The figure-8 pattern on most multi-pattern microphones shows reduced low-frequency response compared to cardioid, because the rear capsule contribution cancels some of the front capsule's bass output.

For most recording situations, you'll use cardioid 80% of the time. The other patterns are useful tools -- omni for room ambience, figure-8 for Mid-Side stereo, hypercardioid for isolating a source in a noisy environment -- but they should be selected intentionally, not left on "whatever was on last time."

Pattern Consistency Across Frequency

A polar pattern specified at 1kHz is only part of the story. Most microphones show pattern variation across frequency. On cardioid microphones, the pattern narrows at high frequencies (becoming more directional) and widens at low frequencies (becoming more omnidirectional). This is a physical reality of acoustic wave behavior relative to the microphone's dimensions.

The Neumann KM184, a small-diaphragm condenser, maintains its cardioid pattern within +/- 10 degrees from 200Hz to 10kHz. The AKG C414, a large-diaphragm multi-pattern, shows pattern widening of up to 30 degrees at 100Hz and narrowing of 15 degrees at 8kHz. This means that at 100Hz, the C414 is picking up more off-axis sound than the specification suggests, which affects how it handles room ambience and multi-source recording.

For critical stereo recording, this frequency-dependent pattern shift causes stereo image width to vary with frequency. The low frequencies sound wider than the high frequencies, which is unnatural. Small-diaphragm condensers with consistent polar patterns produce more accurate stereo images for this reason.

References: Eargle, J. "The Microphone Book" (2019) | AES Papers on "Multi-Pattern Microphone Consistency" (2020) | Neumann Technical Documentation, "Polar Pattern Variation Across Frequency" (2021) | Streicher, R. "Microphone Polar Patterns" Sound on Sound series (2018)