poor man’s vocal booth

A Poor Man’s Vocal Booth?

by Paul Strikwerda in Articles, Studio 13 Comments

Sometimes I come across a certain product and wonder:

It looks promising, but is it any good?

The CAD Audio Acousti-Shield 32 is one of those things.

Designed to “substantially reduce unwanted reflections, echo flutter and environmental unwanted acoustic interference,” does it deliver as promised?

At about $85, could it be the poor man’s vocal booth, or is it a waste of space, and money?


Before I tell you what I think, let’s briefly discuss the whole concept of soundproofing and room treatment. As I wrote in my booklet Building a Vocal Booth on a Budget:

“In this noisy world, soundproofing has become big business. I just Googled the word and got almost two million results. Buyer beware, because the same search will take you into the realm of grotesque claims and pseudo-scientific truths:

“These Soundproof windows will totally eliminate your noise problems.”

“This soundproof foam absorbs up to 66% of sound waves.”

“Our soundproof curtains offer the highest STC performance.”

Do the makers of these products assume we’re that stupid? Think about it for a moment. What does “soundproof” really mean? Most dictionaries describe it as:

impervious to, or not penetrable by sound

Going by the aforementioned claims one could argue that the minds of the makers of these products seem impervious to, or not penetrable by logic. Then again, advertising is all about making noise and not about offering sound proof.”

Gluing some acoustic panels to your wall or on to a “shield” will do nothing to block outside noise from coming in. Auralex foam and its many clones will change the characteristic of the sound inside your recording space, diminishing reflection and reverberation. It absorbs the sound but it does not reduce it.

Yet, CAD claims that their shield can substantially reduce “environmental unwanted acoustic interference.” What does that mean? Would this shield be able to diminish ambient noise? Why not find out? For the test, I purposely chose one of the worst acoustic locations in my house: my basement.


Let’s say you want to use your laptop for a quick recording and you place your microphone in the same room. Before you know it, the computer fan kicks in and starts making noise. Could CAD’s Acousti-Shield magically neutralize the noise? 

I’ll let you listen to the same script twice. You might want to put your headphones on. First you’ll hear my voice without the shield in place. The second time I read the script, the Acousti-Shield cradles the microphone. Just notice if this device is able to get rid of the noise the laptop fan makes.


That’s pretty clear, isn’t it? It confirmed my suspicion. The shield does very little to keep unwanted noise out of the recording. As expected, this thing is no substitute for a properly isolated room. But will it deliver on the second promise? Could it make a room sound more dry? 

Before I play the second soundbite, you should know that I recorded the audio with an AKG C 3000 B microphone, plugged into a Grace Design m101 preamplifier. The 16 bit, 48,000 Hz WAVE recording was converted to MP3 format for this blog.

For the next track I removed the laptop from the room. Once again, you’ll first hear me without the shield. Then I’ll read the same text with the Acousti-Shield 32 in place.


Did you hear a significant difference? A difference worth over one hundred dollars? To be honest with you, I was disappointed. The room didn’t sound dry to me at all. How could a company with such a good reputation bring such a poor product to market? It just didn’t make sense.


The next day I woke up with an idea. What if the product wasn’t the problem? Perhaps I was not using it properly.

I went on a few online forums to find out what others thought of the Acousti-Shield, and I found my answer. The recordings you just heard were made at 9 inches from the microphone. What would happen if I would come closer? 

Once again you’ll hear me read the script twice. First I’ll read it at 5 inches from the mic. Then I’ll add the shield, and keep the same distance.


Now, this is more like it! Distance makes a huge difference.

Thanks to a clever design, you can also move the microphone closer or further away from the 53mm high density micro cell foam. This obviously changes the acoustic result.

The question remains, would I recommend using such a shield for voice-over recordings? Let’s first look at the positives.


The Acousti-Shield 32 is well-made and easy to assemble. For its size it is very light, and unless you have a  cheap mic stand on which to mount it, it won’t tip over. Compared to a product like Harlan Hogan’s Porta-Booth Plus ($189), it is affordable. As long as you stay close to the mic, it manages to tame unwanted reflections.

Here’s what I like less. CAD’s Acousti-Shield is not a unique product. sE Electronics was one of the first companies to come out with such a solution. They called it the Reflexion Filter X. Although I haven’t tested it, it looks very similar.

Unlike Harlan’s porta-booths, the CAD shield isn’t very compact. It’s meant for the studio, not for the road. Even though the shield accommodates a variety of microphones, a popular voice-over shotgun such as the Sennheiser MKH 416 does not fit.

Here’s the big one: where to put the voice-over script? 

I’m usually reading my copy from the monitor in front of me. The CAD shield would block my field of vision. Even if I were to read it from a tablet or smart phone, there is no place to put them as long as the shield is mounted on a mic stand.

In the end I came up with a simple solution. I put the shield on a flat surface that was resting on an old loudspeaker stand. With the microphone on a table stand, there was room for my Nook or iPhone. 


So, is this shield a good investment?

In the end it’s all about expectations. If you get the Acousti-Shield 32 because you need a portable studio, you’re not going to be happy. If you need something to keep ambient noise out of your recordings, this is useless. 

However, if you cannot acoustically treat the room you’re in, and you’d like your recordings to sound more dry, this is an affordable solution, as long as you know how to use it. 

Paul Strikwerda ©nethervoice

PS CAD Audio kindly donated an evaluation model to the author of this blog. Though very much appreciated, this did not influence his opinion.

PS Read more on taming unwanted reflections in “Get the boom out of the room.”