One day I found myself in Staples in the Poster board aisle so…
I bought a standard Foam Staples brand poster board. I cut it down to 15 inches in height. The standard poster board is tri-fold. I wanted four folds so I carefully scored the central panel in the middle, being careful not to cut all the way through.
There’s lots of acoustic foam out there, all of it seems overpriced. I purchased the Sonic Homework Acoustic Sound Foam Kit from Amazon. It’s 8 sq ft of foam and you can see I had enough for all four panels. with two left over pieces the size of what you see draped across the top in the picture. In the bottom I just fold it in half and put it underneath the microphone. My “kit” did not come with any adhesive like it was supposed to, so I just used some household glue (sorry but I can’t remember exactly which type but I think it was just Gorilla glue). I also aligned all the foam wedges vertically because that allowed the least resistance when closing the booth around the microphone and I didn’t have to leave any gaps at the seams.
I then put some Velcro strips on the front sides and I just use a Velcro strap to tighten up the opening so there is very little wood on the bottom exposed while recording. The image below shows the booth with the strap not attached. This idea came from several sources on the internet where people built this kind of booth in a box. I just needed a version with the top open so that my adjustable boom could be lowered inside and removed at will.
The difference is not huge but it is noticeable. Like all things audio, how much this may or may not benefit you, depends on many factors including your voice and the acoustics of your room. I was recording in a room with hard walls and floors. I do light noise removal and then compression and EQ adjustment. Adding the foam didn’t allow me to eliminate those steps but the end result is a warmer more appealing sound. Plus it’s a heck of a lot cheaper and takes up less room than a full sound isolation booth. Once my new Pluralsight course on the Qt C++ Framework is published (May 2014 or earlier) you’ll be able to hear the difference for yourself.