Microphone Directionality

Microphone directionality refers to the variation in sensitivity across 360 degrees around a microphones head. Explore how this characteristic influences sound capture and recording quality.

There are a variety of polar patterns found in microphone design including:

• Omni-directional
• Bi-directional
• Cardioid/uni
• Hyper-cardioid
• Super-cardioid

Polar Descriptions

Omni Directional

Omni microphones pick up sounds equally in all directions. They are great for recording room ambiance and capturing group vocals.

On the downside, they lack background noise rejection and are prone to monitor feedback, which makes them unsuitable for loud and noisy venues.

Bi-Directional (Figure-Eight)

Bi-directional microphones pick up sound in two directions; in front of and behind the microphone, with rejection from both sides.

The front and back sensitivity make them idea for stereo recording and for capturing two or more instruments.

Cardioid/Uni Directional

Cardioid microphones pick up sound from the front and offer maximum rejection at the rear. They are useful for reducing bleed and leakage between sound sources, making them ideal for live performances and situations where feedback suppression is needed.

Cardioid microphones are extremely common and can be found in most studio cupboards.

Hyper Cardioid Directional

Hyper cardioid microphones have a narrown pickup pattern, but also have some rear pickup.

Hyper cardioid mics have better isolation and higher resistance to feedback than cardioids. They are ideal for loud sound situations.

On the downside, as there is some bleed at the rear, you will have to position unwanted sounds on the dead spot sides.

Super Cardioid Directional

Super cardioid microphones have a narrow pickup pattern like a hyper-cardioid, but with a tighter rear pickup.

Directionality Considerations

• Unidirectional Microphones
  • Sensitivity: Less sensitive to off-axis sound compared to omnidirectional microphones, resulting in reduced ambient noise capture.
  • Use Cases: Ideal for cleaner, less reverberant sound in recordings.
  • Distance Capability: Can be used effectively at greater distances while maintaining a high level of direct sound.
  • Proximity Effect: Experience an increase in bass response as they get closer to the sound source.
• Omnidirectional Microphones
  • Room Ambiance: Capture more room ambiance than unidirectional microphones, requiring closer placement to the sound source for direct recordings.
  • Distance Impact: Ambient sound becomes more prominent as the microphone moves further away from the direct sound source. Beyond a certain distance, known as the critical distance, ambient sound may dominate the recording.
• Feedback Sensitivity
  • Unidirectional Advantage: Less prone to feedback, which is the undesirable sound loop caused by audio leaking from loudspeakers back into the microphone, often resulting in a loud squeal or howling.