Microphone Polar Patterns Explained: Cardioid, Omni, and Figure-8

A microphone polar pattern describes how sensitive the microphone is to sound arriving from different directions around its axis. A polar plot is therefore a map of directional sensitivity: the front is normally shown at 0 degrees, the rear at 180 degrees, and the sides at 90 and 270 degrees. It is not a score for sound quality, frequency response, sensitivity, self-noise, or maximum sound-pressure level.

For a PC setup, directionality matters because the microphone may share a room with a keyboard, speakers, fans, another person, or reflective walls. The pattern helps determine which directions are emphasized or attenuated, but placement and the room still matter. Shure explicitly notes that the acoustic environment and microphone placement strongly affect the captured sound.

Cardioid is the familiar heart-shaped directional pattern. Shure describes it as most sensitive on-axis at the front and least sensitive at the rear. That makes orientation important: speaking into the correct side or end of the microphone and pointing its rear toward an unwanted source can matter more than simply moving a software input slider.

Cardioid does not mean that side and rear sounds disappear. Rejection varies with angle and frequency on real microphones, and reflected room sound can still reach the front of the capsule. Directional microphones can also exhibit proximity effect, where low frequencies increase as a source moves very close to the microphone. That is an acoustic behavior, not a USB, XLR, driver, or software feature.

An omnidirectional pattern is intended to maintain sensitivity around the microphone rather than create a front-facing rejection zone. Shure describes omni microphones as picking up ambient or room sound along with the intended source. That can be useful when the goal is to capture a room, several nearby participants, or a source whose position changes relative to the microphone.

Omnidirectional does not mean placement is irrelevant. Moving the microphone closer to one person still increases that source relative to more distant room sound, and nearby surfaces can change reflections. An omni pattern also does not tell you whether the microphone is a condenser, dynamic, USB, XLR, lavalier, headset, or studio microphone; those are separate design and connection properties.

Bidirectional and figure-8 describe the same basic directional idea: strong response at the front and rear with much lower sensitivity toward the sides. Shure documents full response at 0 and 180 degrees and least sensitivity at the sides. This is fundamentally different from cardioid, which is designed around a front lobe and rear rejection.

The geometry enables techniques that deliberately use both lobes or the side nulls. RØDE documents figure-8 microphones in Blumlein and mid-side stereo arrangements, while multi-pattern microphones such as the NT2-A expose cardioid, omnidirectional, and figure-8 modes on the same microphone. The selectable pattern changes directionality; it does not turn XLR into USB or independently define frequency response, sensitivity, or self-noise.

Supercardioid and hypercardioid are more directional relatives of cardioid. Shure documents narrower front pickup than cardioid, but also a key placement tradeoff: their least-sensitive angles move away from 180 degrees and they retain some pickup directly behind the microphone. Pointing the exact rear of one of these microphones at a noise source is therefore not equivalent to doing the same with cardioid.

This is why the pattern name should guide physical placement rather than be reduced to a simple “more directional is better” ranking. A tighter front region can help separate sources in one geometry and be less convenient in another, especially when the speaker moves off-axis or an unwanted source sits in the rear lobe.

A generic cardioid or figure-8 drawing is an idealized summary. Manufacturer polar plots show the response of a particular microphone at specified frequencies, and the shape can change with frequency. RØDE explains the plot as a top-down directional view with sensitivity falling inward from the outer reference rings. When placement matters, the exact product plot is more informative than the pattern name alone.

Also check which side is actually the acoustic front. Side-address studio microphones and end-address broadcast microphones are physically aimed differently even when both are cardioid. RØDE, for example, specifies its side-address NT1 and end-address Procaster as cardioid microphones. Pattern and address type are separate properties.

There is no universal polar-pattern winner for a PC desk. Start with the geometry: where is your mouth relative to the microphone, which sounds are unwanted, where do they come from, how reflective is the room, and will the speaker remain on-axis? A cardioid microphone can be convenient for one-person desk use because it offers rear rejection, while an omni can make sense when several directions intentionally need to be captured. Figure-8 can be useful when front-and-rear pickup or strong side rejection matches the setup.

Software noise suppression, gating, echo cancellation, gain, and level controls operate on the signal after or alongside the microphone capture path; they do not change the capsule’s underlying acoustic polar pattern. Likewise, USB versus XLR describes transport and interfacing, not directionality. Evaluate those layers separately instead of assuming a connector or software feature implies a particular pickup pattern.