Using Directivity to Cut Unwanted Sound

What directivity means

Directivity is how much a mic favors sound from one direction over others. Higher directivity means more rejection of off axis sound and a better signal to noise ratio for a fixed source.

This is a physical property. It cannot be added after recording, so choosing the right mic and angle at capture saves editing time.

Common patterns and reach

Cardioid gives solid front pickup with rear rejection. It works well for one person in a typical room with mixed noise.

Supercardioid and hypercardioid have narrower front pickup and more side rejection, but also a small rear lobe. They trade rear safety for side control.

Shotgun mics have very high directivity along a narrow axis. They help when source and noise are far apart, but need careful aiming and stable mounting.

Use angle to your advantage

Point the most sensitive axis at the speaker and aim the null toward the main noise. Small angle changes can move a noise source into a null with no gain change.

For fixed setups, mark positions. For mobile setups, check a test take after each big move to be sure rejection holds.

Angle to nulls gives rejection without touching volume.

Limits of directivity

Very tight directivity increases sensitivity to small movements and wind. It can also color sound more off axis if the source shifts.

Rejection only works for sounds coming from the right direction. Reflections that bounce into the pickup axis still reach the mic, so room treatment still helps.

Key takeaways

• Pick directivity to match distance between source and noise.
• Aim the null at the main noise source for free rejection.
• Use tighter patterns only when placement can stay stable.
• Expect more movement sensitivity with high directivity mics.
• Keep room reflections in mind, as they limit real rejection.