Microphones – Omnidirectional Verses Unidirectional Microphones

If you are having difficulty in choosing between an Omnidirectional microphone and a Unidirectional microphone for your project, take some comfort in that you are not alone. How do you choose what mic to use for any given purpose? Until now, many do not know the answer to this question simply because they are unaware of how microphones are designed to work.

Some people are pro omnidirection microphones because they believe these will meet most needs and therefor are the default mic for most types of projects. However, this article will clarify the differences and possible confusion between omni and unidirectional microphones, provide understanding in how they work and what situations they might best be used in.

Omnidirectional microphones

Omnidirectional microphones are most often used in situations where you want to capture all of the surround sound in a setting or environment. As the name suggests, omnidirectional microphones receive signals from all directions. Therefore, unlike a unidirectional microphone which captures sound from a more specific direction while filtering out unwanted surround sound noise, the omnidirectional mic is used quite differently.

The polar pattern of an omni microphone is spherical and enables the device to capture sound equally from a 360-degree circumference. This functionality is ideal for example in a situation such as a forest if one wanted to pick up the surround sounds of birds chirping, trees rustling, and the wind howling. The omnidirectional microphone is also often used in concerts where it is important to capture the singer’s voice and the sound of the orchestral instruments through the one microphone.

Now let us take a closer look at a unidirectional microphone:

Unidirectional microphones

Once again, as the name suggests, unidirectional microphones are used for the purpose of receiving or transmitting sound from predominately one direction. The unidirectional function of the microphone however is the very reason why some people criticize using this type without fully understanding what this really means. A unidirectional microphone by design is noise cancelling. As a working estimate this type of 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. It effectively negates unwanted sound and provides better desired sound.

It is the very reason why this type of microphone is a better choice to use for conducting interviews, hosting a live show or presenting to camera for example.

By design it gives the speaker greater focus and therefore greater clarity of message almost by default.

This mic enables you to hear a speaker more clearly even if in a room full of people with a lot of background noise. This clarity is not technically possible with a omnidirectional microphone simply because of its polar pick up design.

A unidirectional microphone is also better when it is needed to be tucked away from view without the fear of muffled noise coming from the body or clothing at the back of the microphone. This direction sensitivity known as the unidirectional polar pattern is a highly useful design feature of unidirectional microphones and is in stark contrast to the polar pattern of the omnidirectional microphone.

This greater understanding between the two types of mics identifies and highlights some of the operational differences each is best suited to due to their inbuilt polar pattern designs and therefore should make it far easier to decide on the best type of mic to use for your recording or broadcast needs.

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