Microphone Patterns
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There are several microphone patterns that determine the directionality of sound pickup. Omni-directional microphones pick up sound equally from all directions, making them good for interviews where mic angle is variable. Cardioid microphones are most sensitive to sound from the front and pick up less from the sides and back, reducing feedback and ambient noise. Bi-directional microphones pick up sound equally from the two sides but not the front or back. Mid-side stereo techniques use a bi-directional mic together with a cardioid mic to allow control over the left-right stereo image during mixing. Hypercardioid and shotgun microphones have a tight, directional pickup pattern that focuses on sound from directly in front
Microphone Patterns
- 1. Microphone Patterns Mics are defined by their pattern vs their sensitivity.
- 3. Omni-directional 360 degree spherical pattern Sounds the same from any angle Good for handheld interviewing since mic angle is not critical Good for lavs worn under clothing since mic angles can shift due to clothing & physical pose
- 4. Cardioid
- 5. Cardioid Aka Uni-directional Heart shaped? Frontal facing Sound diminishes as we move around the mic Most sensitive in the front, reduced at the side, and almost gone in the back
- 6. Cardioid Good for reducing feedback & background noise Okay for trained reporters Cardioid lavs often used for live presentations to reduce feedback Cardioid condenser boom mics used to reduce echo in tight interiors
- 8. Bi-directional Figure 8 shaped Picks up from sides, but not front nor back The sides are merged as MONAURAL, not stereo Left/Right. Cannot control the gain of the two sides independently. Would require 2 cardioid mics to do that!
- 9. M-S Stereo Mid-Side stereo Allows adjustment of left/right width Achieved by varying mix of a bi-directional mic overlapped by a cardioid mic Bi-directional mic is + on one side and – on the other… Cardioid is + on both sides M+S and M—S yield Left/Right
- 10. M-S Stereo Stereo effect is created by matrixing the signals from the two mics Very dependent on correct phase relationships. Big trouble if phase is not maintained throughout xfer and mixdown. Requires headphone matrix box to hear stereo in the field. Great tool if you have control over recording, transfer, edit, and final mix. If not, better to use X-Y stereo technique.
- 11. Hypercardioid
- 12. Hypercardioid Aka “short shotgun” Very directional Slight pickup at tail 180 degrees Least sensitive 120 degrees Compresses foreground/background, just like a telephoto lens Best when deployed above talent. Talent is on-axis, and background noise is off-axis.
- 13. Ultra-directional aka “long shotgun” Extremely directional Slight tail
- 14. About Shotgun Mics Very directional on-axis Less directional as we work around to the sides Least directional 120 degrees off-axis Slight increase in sensitivity at tail May not be flat response off-axis: some freq’s are rejected more than others. Distant, hollow sound Flat off-axis = lower volume, no loss in quality
- 15. About Shotgun Mics When used horizontally (like a rifle), they pick up talent as well as everything behind talent Horizontal may be okay for sound effects, but rarely for dialogue Generally, tighter pattern = more echo Wider pattern = less echo