Unidirectional vs. Omnidirectional Microphones
Omnidirectional microphones are most often used in surround sound environments, and are commonly used for television shows and in concerts. As we earlier mentioned, an omnidirectional mic receives signals from all over.
As a working estimate, a unidirectional mic will pick up less than half as much sound from the sides as from the front, and less than a tenth as much sound from the rear. This provides you more quality sound and less unsought sound.
In a multi microphone configuration, omnidirectional microphones may not be the ideal choice due to leakage. A cardioid mic may be the perfect choice for a multi microphone setup; however, an Omni mic usually provides a superior performance.
In this case, omnidirectional microphones are considered a better choice because they feature: less wind noise, less popping, no bass buildup that is usually caused by proximity effect, less vibration noise and handling, and they can be used right side up or upside down.
Channel separation is usually less precise with an omnidirectional mic compared to a directional microphone. This is so since Omni microphones pick up sound from all over. So, if channel separation is desired, then the ratio between indirect and direct sound may be disappointing with omnidirectional microphones.
Unidirectional microphones do normally feedback at considerably high frequencies. On the other hand, most omnidirectional microphones feedback at bass or lower mid-range frequencies.
What Occasion Should They Be Used?
An unidirectional microphone is mostly ideal as a recording microphone for vocal applications and live recordings. It is the perfect choice when the acoustics of the recording environment are good. A cardioid mic will discard audio from behind, ensuring that there is minimal effect from unpleasant audio.
Basically, cardioids are ideal for:
- Picking up sound in untreated rooms
- Live performances
- Miking up a drum kit
The major drawbacks for using directional microphones are:
- Off-axis coloration
- Sensitive to pop-noises and wind
- Proximity effect
Omnidirectional microphones are widely used in broadcast and other professional applications. They are the best for on-camera interviews because you do not have to worry about pointing the microphone.
Many of the microphones used by television and radio reporters are omnidirectional because it is usually desirable to pick up some ambient sounds in the field to add to the broadcast’s sense of aliveness.
Basically, omnidirectional mics are ideal for:
- Recording in stereo
- Recording a moving target
- Recording a wide sound source
- Recording the sound of the room
When comparing unidirectional vs. omnidirectional microphone, you should be able to identify as well as highlight the operational differences each is best suited for. You can easily achieve this by understanding their inbuilt polar pattern design.
A few things to remember about the omnidirectional mics are: all-round pickup, no proximity effect, low handling noise, low sensitivity to explosive audio, not much isolation, and pickup of room reverberation.
A few things to remember about the unidirectional mics are: selective pickup pattern, coincident stereo miking, superior gain-before-feedback, bigger proximity effect, good isolation, and reflection of leakage and background noise,
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