What Is a Cardioid Microphone? Pickup Pattern, Operation, and Uses

A cardioid microphone is a unidirectional microphone. It picks up sound mainly from the front, less from the sides, and least from directly behind. The name comes from the shape of its polar pattern. When sensitivity is plotted in a circle around the capsule, the outline looks roughly like a heart.

In practice, a cardioid mic favors the voice or instrument it is pointed at and plays down sound arriving from behind it. That makes it a common choice for podcasts, streaming, video calls, vocals and stage use, where you want one main source and less room sound.

How a cardioid microphone works

Most cardioid capsules let sound reach the diaphragm from the front and also, through openings or an acoustic delay path, from the rear. Sound from the front pushes mainly on the front of the diaphragm, so it produces a strong signal. Sound from directly behind reaches both sides of the diaphragm at nearly the same time, so most of it cancels out. That cancellation creates the area of lowest sensitivity at the back, often called the null. Sounds from the sides fall in between.

Two side effects follow from this design. Moving very close to a directional mic boosts low frequencies, which is called the proximity effect. And the pattern is rarely identical at every frequency, so off-axis sound can be both quieter and different in tone. The exact behavior depends on the model, so check its published polar plot and frequency response if you have them.

A cardioid is not the same as a supercardioid or hypercardioid. Those patterns are narrower at the front but have a small pickup lobe directly behind, with their quietest points angled toward the rear sides. An omnidirectional mic picks up roughly equally from all directions. A figure-8 (bidirectional) mic picks up front and back but rejects the sides.

Before you start

Using a cardioid mic is a local, physical setup. It does not need an online service. Recording or call software you use with it may process or store audio in its own way, so check where that app saves files and whether it uploads anything, rather than assuming.

• Find out which part of the mic is the front. End-address mics are spoken into from the top or end. Side-address mics, common with large-diaphragm studio and many USB models, are spoken into from the side marked with a logo, grille marking or arrow.
• If the mic has a pattern switch, confirm it is set to cardioid. Multi-pattern mics often also offer omni, figure-8 or stereo modes.
• Know how it connects: USB, a 3.5 mm jack, or XLR through an audio interface or mixer. XLR condenser mics usually need phantom power from the interface. Dynamic mics generally do not.
• Have headphones ready, so speaker sound does not feed back into the mic during checks.

Step-by-step instructions

The steps below apply to any computer or device. Menu names differ between operating systems and apps, so look for the sound, audio or microphone settings section in each.

• 1. Connect the microphone, or connect the interface it plugs into, and wait for the system to recognize it.
• 2. In your operating system's sound settings, select the microphone or interface as the input device. Select your headphones as the output device if you want to monitor.
• 3. In the app you will use, such as a call, streaming or recording program, select the same input device. Many apps keep their own device choice separate from the system default.
• 4. Place the mic so its front faces your mouth or the instrument. Point the rear toward the noise you most want to reduce, such as a keyboard, fan, open window or stage monitor.
• 5. Choose a working distance. Moving closer increases your voice relative to the room and adds bass from the proximity effect. Moving back sounds more natural but includes more room. A pop filter or foam windscreen helps with plosives when you are close.
• 6. Set the input level, using hardware gain on the mic or interface if available, or the system input slider otherwise. Speak at your normal loudest level and adjust until the meter moves well but never reaches its maximum or clip indicator.
• 7. If your app lets you set the sample rate, match it to the device's configured rate. A mismatch can cause clicks, distortion or pitch problems on some setups.
• 8. Decide on app processing. Noise suppression, automatic gain and echo cancellation in call apps can help or can make speech sound unnatural. Change one setting at a time so you can undo it.

Check the output

Make a short test recording, or use your app's microphone test, and listen back on headphones. Speak from the front, then from one side, then from behind the mic at the same distance and volume. The front take should be the loudest and clearest, the side take quieter, and the rear take the quietest. If all three sound about the same, the mic may be in an omni mode or you may be addressing the wrong side.

Also listen for background noise during pauses, distortion on loud words, and excess boominess. Keep the limits in mind: a cardioid mic reduces sound from behind, but it does not remove it. It also does not stop reflections from walls in front of you returning into the mic. The final quality also depends on the app's processing and on the file format or call codec, which may compress the audio.

Common problems and next steps

• Sound is thin, distant or dull: you may be speaking into the side or back. Recheck whether the mic is end-address or side-address.
• Voice is too boomy: move slightly farther away or turn on the mic's low-cut filter if it has one, to reduce the proximity effect.
• Keyboard or fan noise is still loud: turn the mic so that noise sits directly behind it, and move the noise source farther away if you can. A cardioid's rejection is strongest at the rear, not the sides.
• Room echo remains: get closer to the mic, lower the gain, and add soft furnishings. Directional pickup alone cannot fix a reflective room.
• Others hear themselves echoed in calls: use headphones instead of speakers, or enable the app's echo cancellation.
• No signal: confirm the correct input device in both the system and the app, check app and system microphone permissions, and check phantom power for XLR condenser mics.
• Crackles or dropouts: check that the sample rate matches across the device and app, then try a different cable or USB port.

If a cardioid pattern does not suit the job, consider another pattern. Omni works better for picking up a whole table or room. A supercardioid or hypercardioid gives tighter front pickup, but you then need to place noise sources at its angled nulls rather than directly behind.