Small vocal booth in a project studio

Hi Everyone. I'm planning to build a small isolation booth for recording vocals in my project studio. This is on the 3rd floor of a residential condo, neighbors above and below, one party wall, one interior partition, and two exterior walls with windows. The floor is concrete slab, the partition wall is plasterboard / rockwool / double plasterboard, and the party wall... unknown crappy problem. I suspect it is 5/8 gypsum / light batting / 5/8, with back-to-back outlets, and perhaps a couple of nice open flanking paths, but it is poor at sound attenuation for almost all frequencies. Seems that'll be a construction project for the day we & other owners take legal action! My budget is $500, with room to inflate a few hundred if the result is compelling (dramatically better attenuation or internal acoustics, easier construction.) I hope to achieve good isolation from the rest of the room for tracking sessions, and reasonable isolation from the neighboring units when doing vocal exercises & rehearsing. "Good ... Reasonable?" Lets just say I would love to be able to sing out loud at 3 AM without the neighbors knowing. I usually monitor very low or on headphones, and the music is generally electronic or electric, tracked direct. I haven't drawn the ventilation baffles yet, and there is a problem where the booth meets the wall near the egress door at a wall switch. Might have to angle that wall in. Thanks, everyone for this tremendous site! On to the questions: 1. Transmission thru the rear wall is not as big a concern as thru the party wall, but I would like to do the best I can with it. Should I frame in a rear wall for the booth, adjacent to the rear wall, or just attach the booth construction to it, adding a layer of drywall? This comes down to the choice of adding a 3rd and 4th leaf to the system by framing, or just adding a layer of drywall to a 2-leaf wall, even though I won't be able to interleave the edges of the existing layers with the new ones. I would assume keeping it to a 2-leaf, but since we're not worried about low frequencies, I have to ask. 2. Space is really tight in here, and I will never use this thing for bass amps or drums. Am I wrong in thinking that good single-wall construction (3-4 sheets & rockwool) can perform adequately in the voice range? 3. Is this thing going to sound like hell inside shaped this way, at this size? That is, will I be able to fit enough absorption inside to make it sound OK, while still accommodating an occupant? 4. Is the exterior shape bad for the outer room? I designed it to maximize the booth's volume while leaving enough space to maneuver around it when entering and exiting the studio. I'd go for any details I could add to the outside that would be obvious benefits to the listening environment, while I'm at it. The sketchup file is too big to post here. It can be grabbed from http://razielpanic.com/zero.zip

i would have the booth detached from the walls, and decoupled from the floor. for vox the 2x drywall layers and insulation should be enough. i'd make the booth bigger if you can - 4.25'wx5.3'dx7.5'h

gullfo wrote:

i would have the booth detached from the walls, and decoupled from the floor. for vox the 2x drywall layers and insulation should be enough. i'd make the booth bigger if you can - 4.25'wx5.3'dx7.5'h

Thanks so much for the reply. I'd love to make it bigger, but it is already 5.5' wide 4.5' deep & 8' tall. Are you saying it would be OK for the outer room acoustics to make the booth rectangular with those dimensions? I attached a couple of additional pictures to better show where things are situated & how tight space is so you can see how the shape leaves room to get out of the studio. Rectangular would block the passage more, but there might be a way to move the keyboard racks a little.

if anything, i'd fit the pentagon shape into a corner so i have more usable floor space and the front of it will be still be angled @ 45 degrees...