[You Need a Thneed]

It sounds like you want the whole thing transportable, which means panels should be a maximum of 4’ wide, to have any kind of size, you need a lot of panels, which means a lot of gaps between panels that will all need gaskets.

To contain sound at that level, you are going to need soundproofing on all six sides of the box, and you can’t have any hard surface to hard surface connections from the inside to the outside of the box.

You would have to have a raised floor, set on rigid insulation, or something to that effect. Double studded walls, thick sound batt insulation. The roof would require joists, insulation etc as well.

How big do you want this modular booth to be? An 8’x8’x8’ cube already requires 12 4x8’ panels. Each of which is going to be structural, and then also have sound deadening built in. You need an access to get in, likely two insulated doors back to back.

This is WAY over $2000 already.