Go to first new post new booth...new studio. Cement question

[Wordstrom]

well i've got afew questions for heads that wanna lend a thought. As you can see in the pics i'm just getting started. I'd like to build and proof a 5 foot by 6 foot sound booth. Now as you can see there's a 3 foot cement wall, i'd like to build it in the corner using the cement, but...should I
a) frame the cement wall
b) dry wall the cement wall

Now if you have any suggestions that'd be appreciative...

I'm on a tight budget so I was just gonna sound proof it with ply, insulation, drywall and then acoustic treat it with just matress bedfoam...seems logical.

I'll post before and after pics...should be done by this Saturday morning.