Case Study: The importance of mic positioning

You’ve probably seen it often enough. You’ve probably even done it yourself. When recording video, many people rely solely on their camera’s built-in microphone for audio. The result often ends up being of poor quality due to a few reasons. One can only expect so much from the camera’s tiny microphone. Coloration and noise becomes unavoidable. But perhaps just as importantly, with the subject and presumably the intended source of the sound being at a distance, other ambient and possibly unwanted sounds will also be picked up by the microphone.

Consider the following video clips – same footage, but different microphones. The first one is entirely from my Nikon D7000 DSLR, nearly two meters away in front of me and the guitar.

And now, watch the same video, but this time with the audio coming from the Zoom H2, part of which you can see at the corner of the frame, near the guitar’s soundhole.

Do you hear any improvements? (With the sound, not the playing!)

The first and obvious problem with a camera’s built-in microphone is recording quality. One can only expect so much from it and leads to inherent issues with noise and coloration. But just as importantly, with the camera at a fair distance from the subject and source of sound, the microphone has to be able to compensate with increased coverage. Unfortunately, it cannot be selective with the sound it picks up. Therefore, everything else audible between the camera and the subject will be caught by the built-in microphone.

d7000only
Coverage of the camera’s built-in microphone

The figure above serves to illustrate that second point. With the camera’s built-in microphone having to cover that two-meter gap between the guitar and itself, a lot of room is left open for other sounds to sneak in, so to speak. I was lucky that there weren’t any animals or vehicles making noise in that span of 82 seconds. Unfortunately, I moved too much and made my chair creak right at the end of the performance, and you clearly hear it as the guitar rings at the outro. Not cool.

 

Off-camera microphone coverage
Off-camera microphone coverage

The next figure shows how an off-camera microphone can improve matters. With my Zoom H2 up close, I can set it in such a way that it will only pick up from a short distance (this can also be done from a mixing board). Now, with a cardioid pattern covering only a small area, you leave much less room for extraneous sounds. Together with the Zoom H2 being a superior microphone, its placement will presumably result in a cleaner recording.

I hope everyone can keep this important point in mind, especially when getting into video-related projects.