You Probably Don’t Need a Vocal Booth
Sound isolation, sound quality, sound treatment, & mic choice
First, I’m sorry for the arrogant-sounding title, and I’m also sorry if you’ve already built a vocal booth that you didn’t need. I’m not trying to chastise anyone or tell anyone they’re wrong; I’m just trying to make your life as a home recording person a lot easier.
Yes, you sometimes see vocal booths in TV and movies, but it’s a vestigial part of older studios that were designed to record live bands together with live vocalists; they were doing it to prevent the band bleeding into the vocals, not for the quality of sound you get from a booth.
And yes, you sometimes see other people doing it today, but ask them why. I bet you won’t get a good answer. They probably just saw it on TV or at a friend’s studio.
Quick note for the uninitiated:
Sound proofing = keeping unwanted sound out.
Sound treatment = making your room sound good.
For example, foam is not sound-proofing, because it does nothing to prevent sound from entering the room; it is, however, sound treatment. Sound proofing is usually far more involved (isolated studs/slabs, mass-loaded walls, hat/z-channel, flanking paths, resonant frequencies, etc.).
If you need something to handle sound proofing (i.e. keeping noise out), you could do worse than a booth, but it’s still a non-trivial uphill battle (which I’m not going into today, but I will if you request it). If you want a booth to get better sound quality, you should rethink that.
“Room modes” cause those weird resonances that you experience when, say, singing in the bathroom; you hit that one glorious note and everything rattles like it’s cheering you on. Those room modes also cause terrible sounding recordings. They cause peaks and valleys in the frequency response in a way that may be impossible to correct with EQ.
Small rooms in particular suffer from room modes. Imagine trying to play pool on a 2 foot long table, with the same size/number of balls and the same amount of energy used on a 9 foot table. It becomes messy, unpredictable, chaotic. The same goes for the interaction of sound as it’s reflected off each surface of a small room.
Room Size
Generally speaking, bigger rooms have longer reverberance. You probably knew that already. But, what you may not know is that if you take a reverb, and shorten it (like the reverb in a small room), it will start to sound like a mess of comb filters.
That’s not wrong. In fact, the first algorithmic reverb made use of several comb filters running in parallel.
If you know what comb filtering is, you also know that you probably don’t want it in a raw recording. So what about a sound treatment material like foam to remove the reverberance? Well, first, foam sucks.
In small spaces, the low frequencies become troublesome; they bounce around the room forever, basically just hanging out and causing problems. And that grey foam you see in the studio section of an unnamed big box music store does not handle low frequencies well. The absorption coefficients in the low end are disappointing at best.
Even with better (and cheaper) solutions, like a 2" thick 8 pound / cubic foot mineral wool mounted directly on a wall, the absorption in the low end is not fantastic. When you add an air gap behind the panel so it’s not directly fastened to the wall, the results get better; they get even better when increasing the size of that air gap.
But now your hypothetical vocal booth is starting to get too big to call a booth…
How can you reduce the effect of these objectionable room modes without wasting your time plastering it with ineffective sound treatment? Make the room even larger, treat it with effective materials, and make the air gaps between walls and sound treatment larger.
This hypothetical sound booth is beginning to sound more like a normal room. Maybe even a medium or large room.
Now what do you do without a booth? Your bedroom was probably a better option all along. So, instead of worrying about emulating that “awesome” booth you saw in a poorly researched music video, treat your room and use what you know about your microphones to get decent results.
Bedroom Recordings
I did a literal bedroom recording with a friend of mine recently. The room was not treated at all, so we were forced to make due with whatever we had; the results were 85% as good as tracking in an actual studio.
I picked up some 2'x4' mineral wool panels from an insulation place for about $15 altogether, quickly wrapped them in a breathable fabric (muslin will work if you don’t mind a plain look) to avoid getting all itchy, and I brought them along.
The mic I chose for this situation was an Audio-Technica AT4050; it’s not the most glamorous microphone, but it’s a solid workhorse with a variety of pickup patterns. The pickup patterns are the important part in this type of situation.
We set the 4050 to its bidirectional (aka figure-8) pattern, because the off-axis rejection of a mic with a bidirectional pattern is typically superb. We then pointed the off-axis sides towards the most likely sources of noise; in this case, it was towards the bedroom door (you know, roommates).
From there we used chairs to set the panels in front of and behind the mic, with only enough room for the vocalist. That was it.
The results still had a tiny bit of room reverb, but even with heavy compression, that reverb was not a problem, and it definitely wasn’t causing any noticeable comb filtering. You may not even hear it if you weren’t paying attention.
Update!
For those asking for proof of getting decent sound quality in an untreated room:
TL;DR
- Don’t spend your time on a vocal booth for sound quality; instead use a bigger room
- Use a mic with a bidirectional pattern to reduce unwanted noise from the sides of the mic (including room reverb)
- Call your local insulation place to see what they have in rigid fiberglass/mineral wool panels; aim for 2"+ depth, at least 3 pounds / cubic foot; try 3m 77 spray adhesive to attach the fabric quickly.
- Use strategically positioned sound treatment to reduce the room reverb entering the mic; the room can still be live so long as the early reflections / bulk of the room reverb aren’t getting to the mic.
If you have any questions or hate speech, please leave a comment or send me a message on twitter @quietcreep.
