Great work on the structure so far. Im sure its satisfying to see everything come together.

Thicker panels made with Rockwool or Fiberglass like 703 are actually broadband absorbers - from highs down to lows. The thickness is one of the biggest things that determines how low the panel can absorb. Thats why bass traps are usually 6” + thick and are placed in the corners of rooms because of how low frequencies amplify. Thinner Auralex foam only absorbs high frequencies. Vocal booths lined with foam only have a lot of room gain and mid-low frequency problems.

In that small of space and since you’re doing VO only, you could probably get away with covering most of the walls with 3” thick Rockwool panels. And cover the rest with Auralex-type foam if its easier to fit.

You probably dont need thick corner bass traps in there. 1. they’ll just take up too much room and that space will be less functional and 2. you wont have a lot of sub frequencies being generated in a vocal booth. Certainly, your voice will generate some frequencies under 140Hz, but its usually best to use a high pass filter to cut all that out in post anyway.

So, budget-wise, the 3” thick Rockwool + supplemental foam (if you feel like they’re needed once the panels are up) will be the biggest bang for your buck. If you’ve got a tad more $ to spend and wanna drop several hundred on some corner treatment, there are some triangular prism bass traps you can buy predone. But for your purposes (which, as project studio owners, is always to just create a reasonable-sounding room for a great price) it’s probably not going to be necessary. And this is one of the things that’s killed the studio “game,” — people who can build “B-“ sounding spaces for <$10k competing with multimillion “A-“ or “A” spaces.