Why I Hate Pre-Fab Vocal Booths

Let's start with what's right about pre-fab vocal booths. Everyone knows what I mean by this term, right? I won't mention any trade names. Basically it's a box. Usually a black box, about the size, shape and comfort-level of a telephone booth. Its purpose is to isolate you and your microphone from outside noise.

And that's what's right about these boxes. The owner has correctly identified a problem - noise incursion - and has invested in a solution. Bravo! Best of all, the solution often works, to a large extent. It gets lawnmower roar, dog barks and traffic hum out of your voiceover.

But, as often happens on our planet, this solution creates a new set of problems.

I can always identify a track recorded in one of these boxes by the telltale resonance peaks. Often the high end is overly damped, too, so it sounds like your mic's high-frequency response is being lopped off. But it's those darned resonances that've caused me to dub these booths "audio coffins."

All rooms have modes - the stereophiles used to call them "standing waves." Every sound-frequency has an actual physical size, even though you can't see it. When that size corresponds to one measurement of your room (or half that measurement, or a quarter), the sound doesn't fade quickly into the ambience, as it should. It hangs around like a bad odor because it's being reinforced by the room.

Maybe you remember playing in the bathtub when you were little. If you pushed the water rhythmically at just at the right time, the waves got bigger. If you pushed the water in a different rhythm, there were just random splashes. Those water waves, like sound waves, are amplified when the frequency (how often you push) corresponds to the dimensions of the enclosure (the tub).

In a recording studio, the room dimensions have been calculated to spread out those resonances, and move them down in the spectrum, where they're harder to hear. And there are no parallel walls. In an Audio Coffin, the walls are not only parallel but close together, so the resonant frequencies are pronounced, and well up in the audible range.

One voice actor sent me files from his black box recently, and I was able to reveal with EQ where the resonant points were. Three of them were very easy to hear. One midrange note actually hung around for half a second after he had spoken it. That's a lot of interference with whatever you're saying next.

This creates a problem downstream because the weird sonic imprint makes your voice track hard to mix.

Here's an objection that comes up: "None of my clients has complained." Let me rephrase that and see whether it still sounds convincing. All of the people who find my work acceptable, find my work acceptable. A bit of circular thinking, I think. Obviously the people who use your product find your product usable - but what about the vast universe of potential clients? What about your v/o competitors whose tracks are somehow easier to mix, though the client may not understand why?

OK, so what is the solution to the problem created by this solution? In my view it's to get off the pre-fab boxwagon altogether. You can build your own booth out of standard materials without parallel walls. You or your contractor will have to learn a little bit about studio construction, but the information is available. The downsides are that your custom booth will necessarily take up more space, and it won't be portable.

But at least you won't be trading noise for bad sound.

© Dan Popp 2017


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