By: Mark Yoshimoto Nemcoff, WordSushi.tv
Last year, when I was working on this odd little syndicated television show, we were shooting at CES with a stripped-down mobile crew. Usually on a gig like this you would have a cameraman (shooter) and a separate sound guy to handle all the audio and possibly hold the boom mike. Since we were a low budget production and were geared up to be fast on our feet from setup to setup, we just used a very experienced cameraman who had to reluctantly pull double duty shooting and recording audio. Now, this was a guy who has shot countless hours of unscripted action on dozens of network reality shows - a shooter who really knows how to capture the moment. So given my background and my degree in audio engineering and production, I thought it would be a natural question to ask whether the lavalier mic he was pinning to my chest was, in fact, a cardioid or an omnidirectional.
To my surprise, it turned out that not only did my extremely experienced shooter friend not know the answer, but he didn't even know the difference.
And it occurred to me that even though the difference between the two types of microphones is great, even those who have hundreds and thousands of hours of video production under their belts may not know what is truly an essential bit of audio recording knowledge, especially if you are shooting in the field.
Microphone elements have different pickup patterns for different purposes. An omnidirectional mic is built to pick up audio, as you may guess, from all around the microphone - front, back, sides, etc. If you were to illustrate the audio pickup pattern of an omnidirectional microphone, it would look something like a giant balloon arching out in a spherical radius. In short, an omnidirectional microphone tries to pick up everything it can in the environment is placed into.
In contrast, a cardioid microphone is built for the purpose of isolating the audio it picks up so that it is only capturing sound occurring in front of it, and to a lesser extent, from the sides as well. Cardioid microphones are sometimes referred to as directional microphones for just this very reason. One of the primary reasons to select a cardioid microphone over an omnidirectional microphone is to reduce the amount of ambient noise picked up in your recording.
Omnidirectional microphones are great when you have a fixed microphone position and a moving sound source, however as you can imagine along with your source, your omnidirectional mic is liable to pick up a lot of noise that you may not want. Omnidirectional lavalier microphones are helpful when two people in close proximity to each other are both speaking, such as a situation where one person is interviewing another face-to-face, or in a pinch when you have two people on camera and only one microphone.
However, in most cases when the on-camera talent is flying solo in front of the lens, your best audio results by far will come from using a cardioid microphone that will predominantly pick up their voice while rejecting most ambient noise. Most handheld microphones utilize directional/cardioid pickup patterns. What I have noticed though is that not every lavalier mic falls into this category.
When choosing any microphone for your video set up, don't be afraid to ask what kind of pickup pattern it has. I have noticed a vast majority of inexpensive lavelier microphones are of the omnidirectional variety. This may work for certain situations (say you are shooting a wedding and can only put one microphone on one participant), however that same omnidirectional microphone may not give you the professional audio clarity you desire if you are doing a solo standup directly to camera. In short, if you are looking to achieve the type of audio results one would expect from a newscast or any television show host, you need a cardioid mic to sound like a pro.