Microphone Polar Patterns

What is a microphone polar pattern?

A polar pattern (also called a pickup pattern) is a circular graph of a microphone's sensitivity. The mic sits in the center, facing 0°. The line shows how loud a sound of equal strength would register if it arrived from any other angle. Where the line bulges out, the mic hears well. Where it pinches in, the mic rejects sound. The deepest dips are called nulls.

• On-axis: the direction the mic points, where it is most sensitive and sounds most natural.
• Off-axis: everything else. Sound here is quieter and, on most directional mics, duller in tone.
• Rejection: how many decibels quieter an off-axis sound is compared with the same sound on-axis.

Polar patterns also change with frequency. A mic can be tight at 8 kHz and almost omni at 200 Hz, which is why generator or HVAC rumble gets onto a track even when the mic is aimed away from it. For location sound, the pattern is a practical question: how much of the set do you want to hear?

Types of microphone polar patterns

• Omnidirectional: equal sensitivity in every direction. It has no proximity effect (bass boost up close), handles wind and handling noise best and sounds the most natural, but it records the most room. This is the standard for lavalier microphones: a lav sits a few inches from the mouth, and the angle to the mouth changes every time the actor turns their head.
• Cardioid: a heart-shaped pickup, strong in front, about 6 dB down at the sides, with a null directly behind. It's forgiving and warm, common on voice-over mics, but a bit wide for a boom on a noisy location.
• Supercardioid: narrower in front, about 9 dB down at the sides, with nulls at roughly 125° and a small rear lobe.
• Hypercardioid: narrower still, about 12 dB down at the sides, with nulls near 110° and a larger rear lobe. Short hypercardioid pencil condensers are the standard interior boom mic.
• Figure-8 (bidirectional): equally sensitive front and back, with deep nulls at both sides. It's rare on set but used in mid-side stereo recording.
• Shotgun (lobar): a supercardioid or hypercardioid capsule behind a long slotted interference tube that narrows the front pickup further at high frequencies. It's the classic exterior boom mic.

Tighter patterns give you reach. Compared with an omni, a cardioid can sit about 1.7 times farther from the actor with the same ratio of voice to room sound, a supercardioid about 1.9 times and a hypercardioid about 2 times. On a wide shot, where the frame line pushes the boom up, that distance matters.

Cardioid vs. supercardioid: which one for dialogue?

The practical difference is where the nulls are and how much side noise gets through. A cardioid's single null sits directly behind the mic. On a boom aimed down at the actor, it points at the ceiling, which is rarely where the noise comes from. A supercardioid's nulls sit at about 125°, angled up and outward, closer to where a camera, a window or the crew usually is, and its side rejection is noticeably stronger.

The price is the small rear lobe: a reflective ceiling or a lighting ballast directly behind the mic comes back in. A good boom operator tilts the mic until the noise falls into a null instead. For most film dialogue, the supercardioid or hypercardioid wins. The cardioid suits quiet, treated spaces where a wider, warmer pickup helps, like a voice-over booth or an interview in a dead room.

Shotgun mic pickup pattern

A shotgun's pickup is usually drawn as a long, narrow lobe, but that shape is accurate only at high frequencies. The interference tube cancels side sound by letting it reach the capsule through the slots at slightly different times. That works for short wavelengths and barely at all for long ones. The result is a mic that is very directional for consonants, fairly wide for low frequencies and colored off-axis: voices drift thin and phasey as the actor leaves the lobe.

Outdoors, with no walls to reflect sound, the trade is worth it: more reach, more traffic rejection and a boom that can stay above a wide frame line. Indoors it backfires. In a small room with hard walls, the voice bounces off every surface and arrives from the side, and the tube adds a hollow, boxy color that no EQ fully removes. That's why many mixers use a short hypercardioid for interiors and save the shotgun for exteriors and big spaces. Whatever the pattern, aim at the mouth, not the chest.

How to choose a polar pattern on set

Start from the space and the shot, not from the mic cabinet:

1. Listen to the location. Find the noise — a road, a fridge, a generator — and plan the boom angle so the loudest source falls into a null. Better still, turn it off.
2. Match the pattern to the room. Use a hypercardioid in reflective interiors, a shotgun outside and in large halls, and an omni lav on the body.
3. Mind the frame line. Tight patterns buy distance, but they don't replace getting as close as the frame allows.
4. Stay consistent. Record room tone with the same mic, pattern and position as the dialogue so the editor can fill gaps invisibly.

If the production track is still unusable, the line goes to ADR. Clean on-axis dialogue lets the mixer place the voice during sound mixing rather than repair it. For how dialogue fits the rest of the soundtrack, see sound in film.

Planning mic choices on a FlashBoards board

Mic choice depends on what the picture team decides: how wide the frame is, how hard the walls are, where the windows and the road are. On a FlashBoards board, a sound mixer can keep location photos, storyboard frames and notes like "hard kitchen, hypercardioid, null toward the fridge" next to each scene, so mic decisions are made during the recce instead of on the shoot day.

Further reading

John Eargle, The Microphone Book (Focal Press). Tomlinson Holman, Sound for Film and Television (Focal Press).