Recording Meetings At An Oddly Shaped Table

My good friend Adam knows quite a bit about a great many things. He is excellent at directing his staff to fix workstations and roll-out machine images. Like most people who grew up in the internet age, he’s fairly comfortable with searching Google, leveraging his supreme meta-knowledge, and finding pretty great answers.

[Very smart, accomplished people search for things you might assume they should already know. It’s ok. That knowledge exists on the internet for a reason. You shouldn’t have to store all of it in your brain along with the filmography of that weird character actor, all the notes in F# major scale, and the name of that kid who fell backward out of their chair in high school geography.]

As a part of his job, he was tasked with recording regular board meetings. The table they met at was in a wide U shape, and he found it impossible to get a clean recording (for transcription and recordkeeping) on his Zoom H4n with the two onboard stereo-pattern microphones. Speakers would be too low to be heard and the recording had too much echo to be easily understood.

I can think of multiple solutions to this problem. They all depend on how much money you want to spend and how much time you want to invest in making it work. The simple solution I offered him added marginal expense and works perfectly.

Boundary Microphones

Let’s talk about Boundary (or PZM) microphones.

Think of microphones as having a position relative to surfaces around them and are subject to reflections from each of those surfaces. This might be 3 feet from the ceiling, 5 feet from the right wall, and so on. The range of distances between each reflective surface means that sounds bouncing from each surface and the sound source will all arrive at the microphone at different times.

This means they start to interact in negative ways as they are minimally delayed in different amounts, then get picked up together at once by the microphone pickup. Some of each sound source gets canceled out. Depending on the type of microphone, the size of your room, and what it’s made of, this could result in much worse sound. If you can find a way to minimize the amount of reflection and pick the right microphone, your sound becomes much more direct and cleaner.

Boundary microphones solve this by putting the microphone as close as possible to a reflective surface. This is ideal in a meeting because you can place microphones on the table surface, which extends the boundary below the microphone to essentially the entire table.


The solution to Adam’s problem was to add in two boundary microphones, similar to the Audio Technica I included a picture of earlier. They both connected over XLR (professional) connections, allowing him to place one boundary microphone midway down each arm of the U-shaped table and point the H4n’s onboard microphones at the base of the U for the remaining speakers, easily covering all three sections of the table. Ideally for mixing, I would like to only use the same type of microphone for a setup like this. This was for record-keeping though, an ideal situation for good-enough but not perfect.

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