Every microphone has some sort of directionality. Directionality refers to the sensitivity microphone to sound from different directions. Microphones pick up sound from one direction, all directions, or a particular combination of directions. We can classify these directional properties into 3 primary categories: unidirectional, bi-directional, and omnidirectional.
A microphone’s directionality can be laid out on a graph called a polar pattern.
• Omnidirectional Pickup Pattern
This is the most naturally sounding polar pattern. Microphones exhibiting this pattern have a capsule with only one side of its diaphragm exposed to sound vibrations. They pick up sound equally from all directions because they have equal sensitivity at all angles. You do not need to aim an omni in a certain direction to record sound.
The downside to this type of mic is that you cannot point it to an undesired sound source as it will pick up background noises.
• Unidirectional Pickup Pattern
Unidirectional microphones pick up sound predominantly from a particular area, which is usually the direction that the barrel of the mic is pointing. They offer a great frequency range and reject unwanted background noise.
No microphone is 100% unidirectional.
• Bidirectional Pickup Pattern
Bidirectional mics only pick up the sound coming from their front and rear areas. They are ideal for podcasting and radio interview recordings. Sometimes they are used as backup microphones for talk show hosts.
Aside from these three basic patterns, we also have super-cardioid and hyper-cardioid microphone pick-up patterns. Hypercardioids are slightly unidirectional. They have a more exaggerated front-end pickup pattern than most regular unidirectional mics. What’s more, they eliminate almost any sound coming from their rear and sides.
Super-cardioids offer high rejection of ambient sound. They have a narrower sensitivity focus than most cardioid mics. They’re designed to pick up sound coming from the rear; and are resistant to audio feedback.
From the information we have here, you can already tell that the best way to pick up sound equally from all directions is to utilize an omnidirectional pick-up pattern. Let’s talk a little bit more about omnidirectional microphones.
Whether you choose to speak from the side, front, right, or left side of an omnidirectional mic, the microphone will record your voice with equal gain.
Omnis have a circular polar pattern that allows them to pick up sound equally from all directions. Unlike their unidirectional counterparts, they have a wide range of applications because they offer users great flexibility in how they pick up sound. Musical bands, for example, use omnidirectional mics to record the sounds of instruments and the voices of backup singers.
In some instances, however, picking up sound from all directions is undesirable. A good example would be an artist recording their music at home. He/she would avoid using an omnidirectional mic as it would pick up unwanted background noises. Instead, he/she would go for a unidirectional mic with a thin diaphragm.
Other applications for the omnidirectional pick-up pattern include recording audio for live music performances, interviews, press conferences, podcasts, and orchestras.
Side-note: Omnidirectional mics become more directional at higher frequencies. High-frequency sound waves reach microphone diaphragms faster than low-frequency sounds because they have shorter wavelengths.
My recommendations for a good omnidirectional microphone would include the Movo HM-M2 and the RØde Reporter Omnidirectional Microphone.
This dynamic omnidirectional handheld mic is perfect for – but not limited to – Youtube audio recordings, multi-personal podcasts, and interviews. It is made of long-lasting aluminum alloy with a finish of a crisp black matte, which makes it blend well into shots.
The microphone comes with an isolated omnidirectional microphone capsule that allows you to record clear audio. You can use it with a pop filter to handle unwanted noises. It has a frequency range of between 70Hz and 15kHZ.
It maximizes audio clarity by reducing plosives, which makes it a favorite among interviewers.
Weighing in at about 6 ounces, this mic from Movo is easy to handle when performing lengthy representations and conducting interviews. It doesn’t require external phantom power – making it the perfect mic to use with any smartphone.
If you plan to buy and use this microphone with a camera, be sure to get an adapter cord because it doesn’t come with one.
This is a reliable, high-quality mic with an omnidirectional pattern. It has a long, sleek design that makes it an elegant mic to use for audiovisual applications like television interviews. Although I prefer something more discrete for presentations, the Rode Reporter can make a great presentation microphone.
The mic comes with a windscreen that enables you to capture sound clearly in almost any environment. It features a multi-layered mesh that helps maintain good vocal clarity as it minimizes unwanted background noises. Its frequency response allows for maximal intelligibility and crisp, clear voice reproduction.
I wouldn’t use this microphone at a busy, loud event as it will pick up a lot of background noise. It is also prone to audio feedback, which would be more frequent at an event with loudspeakers.
Tips for Buying an Omnidirectional Microphone
First, analyze what you need in a mic. Do you want to record a song? Do you want to conduct interviews in public? Understanding your needs will enable you to find an omni with essential features.
Second, you need a budget. If you’re going to go for high-end microphones like Rode, AKG, Sennheiser, and Movo, you need $700 to $2000. Don’t focus too much on prices and forget to check the durability and usability of the mic you want to buy.
Lastly, buy from a trusted source. A good vendor will sell you the original product and ensure it gets to your doorstep in tiptop condition. They can also advise you on the best item to buy to achieve desirable results.
Although omnidirectional pick-up patterns aren’t perfect, they have proven their worth in some applications. If you’re looking to record Youtube videos, TV interviews, or a podcast, you should go for high-quality omnidirectional mics with features that minimize background noise.