Microphones & polar patterns
Dynamic vs. condenser, where each pattern picks up, and mics for meeting rooms.
In a conferencing room the microphone has one job: capture the people talking, and as little of everything else as possible — the HVAC, the projector fan, the room's reflections, and above all the loudspeakers playing the far end. Two choices decide how well it does that: how it converts sound (its transducer type) and where it listens (its polar pattern).
Dynamic and condenser
| Dynamic | Condenser | |
|---|---|---|
| How it works | A coil attached to the diaphragm moves in a magnetic field | The diaphragm is one plate of a capacitor; built-in electronics read the change |
| Power | None needed | Phantom power (usually +48 V) or a battery |
| Sensitivity | Lower — needs more preamp gain | Higher — picks up quieter, more distant sound |
| Detail | Smoother; less sensitive to fine detail | More detailed, especially at high frequencies |
| Typical home | Handheld vocal mics, lecterns, loud stages | Gooseneck, boundary, lavalier and ceiling mics |
- How it works
- DynamicA coil attached to the diaphragm moves in a magnetic field
- CondenserThe diaphragm is one plate of a capacitor; built-in electronics read the change
- Power
- DynamicNone needed
- CondenserPhantom power (usually +48 V) or a battery
- Sensitivity
- DynamicLower — needs more preamp gain
- CondenserHigher — picks up quieter, more distant sound
- Detail
- DynamicSmoother; less sensitive to fine detail
- CondenserMore detailed, especially at high frequencies
- Typical home
- DynamicHandheld vocal mics, lecterns, loud stages
- CondenserGooseneck, boundary, lavalier and ceiling mics
Almost every microphone in a conference room is a condenser: they are small, sensitive and can sit some distance from the talker. Dynamics shine where sound is loud and close — a presenter's handheld at an all-hands, say.
Polar patterns
A polar pattern shows how sensitive a microphone is to sound from each direction around it. Straight ahead is on axis (0°). Most patterns are a blend of two ingredients — an omnidirectional part that hears everything equally, and a figure-8 part that hears front and back but nothing from the sides. Change the mix and you get the familiar family:
- Omni — equal in all directions. Natural sound, no aiming, but it hears the whole room.
- Cardioid — heart-shaped, with a null directly behind. The default directional mic.
- Super- and hypercardioid — tighter at the front, with nulls moved to the rear sides and a small lobe of pickup directly behind.
- Figure-8 — front and back equally, with deep nulls at the sides.
Null
Relative to the talker straight on axis.
180°
Aim the null at the loudspeaker or the noise.
3.0× · 4.8 dB
How much less diffuse room sound it picks up than an omni.
1.73×
How much farther away it can be than an omni for the same direct-to-room balance.
Idealised first-order patterns (sensitivity = A + (1 − A)·cos θ). Real microphones narrow at high frequencies and widen at low ones; check the manufacturer's polar plots.
Rejection and reach
A directional mic picks up less diffuse sound — the reverberant wash that arrives from every direction at once. The directivity factor measures this: a cardioid hears about a third as much room sound as an omni (a factor of 3), a hypercardioid about a quarter (4). Its square root, the distance factor, says how much farther from the talker the mic can be and keep the same balance of voice to room. That is why a cardioid gooseneck can sit further away than an omni without sounding distant.
Proximity effect
Directional microphones boost low frequencies when the source is very close — the proximity effect. It makes a close-talked handheld sound warm, and it makes a talker leaning into a gooseneck sound boomy. Omnis don't have it. A high-pass filter in the DSP is the usual cure.
Microphones in meeting rooms
| Type | Where it goes | Trade-offs |
|---|---|---|
| Gooseneck | On a table or lectern, pointed at the talker | Close and clear; clutters the table, depends on talker discipline |
| Boundary | Flat on the table | Unobtrusive; picks up table noise — typing, cups, paper |
| Lavalier | Clipped to clothing | Consistent distance; needs a wireless system and batteries |
| Ceiling array | In or on the ceiling | Clear table and flexible seating; furthest from talkers, so room acoustics matter most |
- Gooseneck
- Where it goesOn a table or lectern, pointed at the talker
- Trade-offsClose and clear; clutters the table, depends on talker discipline
- Boundary
- Where it goesFlat on the table
- Trade-offsUnobtrusive; picks up table noise — typing, cups, paper
- Lavalier
- Where it goesClipped to clothing
- Trade-offsConsistent distance; needs a wireless system and batteries
- Ceiling array
- Where it goesIn or on the ceiling
- Trade-offsClear table and flexible seating; furthest from talkers, so room acoustics matter most
Beamforming ceiling arrays combine many small capsules and use DSP to form steerable pickup lobes, so the array can follow talkers or cover defined zones of the table. They depend heavily on a well-treated room — even the best array is several times further from the talker than a gooseneck.
Key takeaways
- 01Dynamic mics need no power and handle loud close sound; condensers are more sensitive and need phantom power.
- 02Polar patterns blend omni and figure-8 pickup: omni, cardioid, super- and hypercardioid, figure-8.
- 03A cardioid's null is directly behind; tighter patterns move the nulls to the rear sides and add a small rear lobe.
- 04Directional mics reject diffuse room sound and can work further away — but moving closer helps more.
- 05Point nulls at loudspeakers and noise sources; beamforming ceiling arrays rely heavily on room acoustics.
Check your understanding
Q1A loudspeaker sits directly behind a table microphone. Which pattern rejects it best?
Q2Which statement about condenser microphones is true?
Q3A talker leaning in close to a cardioid gooseneck sounds boomy. What's happening?