Small studio soundproofing project - feedback wanted!

Hello! I would like your help with the planning of my 1st soundproofing project. I plan to convert a storage unit into a studio/practice space at my home near Seattle, WA USA. USAGE: This will be a personal recording/practice studio. I am a songwriter wanting to record demos of my music, as well as have a quiet place to be creative where I can't hear others and they can't hear me. I will mix rock and dance demos using near-field monitors and no subwoofer. I will also sing and play piano (with a keyboard through the monitors). This is a personal project - I will be doing most of the construction, with the help of my dad. REQUIREMENTS: I am NOT looking for perfection. I hope to not be able to hear the loudest singing/shouting beyond of this room, and reduce other sound transmission so that neighbors and passersby cannot notice me over outside environmental noise. ATM I don't have an SPL meter but shouting can be heard from about 35ft, and loud music from about a 60ft radius outside (mostly bass). I will not attempt to significantly reduce bass. THE SPACE: The room is on ground level, and connected to the end of the house on one side with another 6ft wide storage space between them. Above the room is an unoccupied third storage unit. The house is cinder block construction (the storage units, including this room are not). The other three walls of the space are exterior, including the door, which faces into an alley opposite the rest of the building. The remaining two sides closely face neighbors. The room is small: 7.5' x 12', and about 7'6" tall. Its concrete foundation is raised 10” above the plywood floor and juts in ½” from the wall facing the house and 2.5” from the other 3 walls. The 2x4 wall studs are mostly 16” OC, but unevenly spaced in places. There is DW on the outside of the 3 exterior walls and plywood on the outside of the wall separating the rooms. Aside from the door, there are no windows. The ceiling joists, which sit on top of a 4 x 10 support beam above the door and cantilever beyond that wall were completely exposed to the outside (protected by thin, unsealed exterior panels). These joists were also shared by the adjacent storage space. In both cases I installed insulation and compression fit 2 x 10 boards between the joists, which I may seal if necessary. The floor is plywood, and judging from the nail patterns, most likely sitting on top of joists that are mounted to the concrete bed below. The current door is solid core. It is framed askew with gaps between it, the frame, and the jamb. THE PLAN: I have a budget of 1000$ (with some wiggle room if necessary) I plan to use mostly DD + GG because it seems the best option considering spacial and budgetary constraints. Unfortunately this was one of the last things I researched, but before I post the rest of my tentative plan, I would like feedback regarding an issue that the project is contingent upon, which is how to soundproof the walls given the concrete foundation. I have read that the best way to soundproof concrete is to decouple with a large air cavity. This is not possible considering size constraints. Are there any viable alternatives that would meet my requirements? Attached are pictures of the studio. Please let me know if you would like any other details and I will try to provide them Looking forward to seeing your thoughts!

" I have read that the best way to soundproof concrete is to decouple with a large air cavity. " Well, that is correct. But not like you think and not like whomever made the post you read was thinking. The simple thing is a mass/air/mass assembly. This is a body of mass...and air space or decoupling method and another body of mass. Now this applies to everything everywhere in the world of acoustics in the attempt to create high levels of isolation with light weight materials. But direct to your statement, exactly how would you decouple concrete? Kinda silly isn't it, when you try to decouple something that is 100 pounds per cubic foot with light weight wood or other lightweight materials. When you have a concrete base or slab that is damped by the earth(depending on the Earth below it) this is often the best TL you are going to get in your build. "The floor is plywood, and judging from the nail patterns, most likely sitting on top of joists that are mounted to the concrete bed below. " I would look into getting rid of this wooden floor. REASON: This is a coupled, meaning not a decoupled aspect of the mass/air/ mass assembly. An Earth damped concrete slab is going to, all things considered, be the better part of the isolation. Your existing situation with this floor is currently the weak place and the removal of this wood floor will gain you head room and volume, two important things.

Hi there "pacifiesta", and Welcome to the Forum! :) Unfortunately, the hosting service for the forum screwed up when they moved us to a new server last week, and they somehow managed to lose all photos that were uploaded between the 15th and 21st of December... including yours! So if possible, please could you upload those again. Just edit your post and re-insert the photos in the correct place. That should fix it! Sorry about the problem!!! :oops: - Stuart -

Soundman - Ok. Thanks for the heads up. I've reposted the photos xspace - My source is: http://www.soundproofingcompany.com/sou ... af-effect/ near the bottom of the page. The graph shows improvements above 100hz for concrete walls: "For concrete walls and ceilings, bigger air cavities are better, but decoupling the mass is the real key. While lower frequencies still suffer, the great majority of the frequency spectrum is improved. As long as the system is coupled, performance will be seriously compromised in the low frequencies". However, what you are saying makes sense, and for my purposes may be enough. It would be great to remove the plywood floor, too. So if I don't treat the slab, will that create flanking paths upwards through the base of the wall assembly, reducing the efficacy of the wall treatment? HERES THE REST OF MY PLAN... WALLS: I plan to use DD + GG on the interior walls. Will the beam and 2 x 4’s surrounding the door reduce the effectiveness of DD + GG, because there is no air gap in the wall assembly? DOOR: I plan to install and seal a solid core door based upon Rod’s Gervais’ book. Because of the gaps in the frame, pictured, I plan to replace the current one with another used pre-hung. If there is room and extra $, I might actually install it in such a way that I could install another communicating door later down the road if I choose to. What can I do about the gaps surrounding the door jamb? (See pictures. Ideas I have are using spray foam, a layer of MLV, or acoustical sealant) This is something I haven't found online: aren't there flanking paths through door into the wall and ceiling? CEILING: The space above is unused, so impact noise isn't an issue. I prefer to use DD+GG if this works (although I have not seen many examples of this online), Also, will the 2x10s I fit between the joists above the door help because they create a better seal, or hurt because they create possible resonating air cavities (about 1 cubic foot per cavity)... but maybe not if the room is treated properly? See the picture labeled "Ceiling with door." Here is a diagram of the situation, perspective is along the length of the ceiling joist: EDIT: the diagram's formatting wasn't retained after posting. I took a screenshot of it. See the attached image. ELECTRICAL: Super basic. I would like to have four total plugins, either as two single gang or one double-gang outlet. It seems that surface mounted electrical boxes would be the easiest and most effective barring feedback suggesting otherwise I will connect the home's main internet router to one inside the studio, via internet cabling run through the walls and threaded between stud cavities. This is something I haven't seen an answer for online: When electrical fixtures are installed, is there a significant flanking path created by the wires themselves? If so, can anything be done to reduce transmission? I am serious about this project, but it is also a brand new venture for me. The amount of variables are overwhelming. I am willing to do the work necessary, but will need help because I don't know what I don't know. If you don’t think this plan will meet my needs, could be slightly modified with great improvements please let me know. If there is something I am forgetting please let me know. I look forward to your thoughts!

"xspace - My source is: http://www.soundproofingcompany.com/sou ... af-effect/ near the bottom of the page. The graph shows improvements above 100hz for concrete walls: "For concrete walls and ceilings, bigger air cavities are better, but decoupling the mass is the real key. While lower frequencies still suffer, the great majority of the frequency spectrum is improved. As long as the system is coupled, performance will be seriously compromised in the low frequencies"." Sounds right. I would re-write it and say that "decoupling is the most important effect you can do to achieve higher isolation especially in the lower frequency area, but the bigger air cavity you can achieve the better you are in the quest for higher transmission loss." I have no idea why "While lower frequencies still suffer, the great majority of the frequency spectrum is improved." is even in there. When you decouple, and this is the BEST thing you can do to achieve higher isolation, the entire overall TL is improved. I have to think that it is because they are talking about introducing small air cavities into the assembly since this is about walls...not floors. There is no reason that you cannot mass a block wall without creating an air mass, if the TL was required. But I ain't no acoustician.

xSpace wrote:

Sounds right. I would re-write it and say that "decoupling is the most important effect you can do to achieve higher isolation especially in the lower frequency area, but the bigger air cavity you can achieve the better you are in the quest for higher transmission loss." I have no idea why "While lower frequencies still suffer, the great majority of the frequency spectrum is improved." is even in there. When you decouple, and this is the BEST thing you can do to achieve higher isolation, the entire overall TL is improved. I have to think that it is because they are talking about introducing small air cavities into the assembly since this is about walls...not floors. There is no reason that you cannot mass a block wall without creating an air mass, if the TL was required. But I ain't no acoustician.

I see your points. I don't know why lower frequencies suffered in this example, but that's the case according to their data. Before you suggested removing the plywood, I was considering treating the floor. What would be left over is the exposed 10" vertical (wall) portion of the concrete bed which connects to the stud walls' base plates, and which I wanted to treat as well. I understand that as is the concrete may provide good TL. My question is: if I leave any portion of the concrete bed untreated, will there be significant flanking transmission from the concrete up through the base of the walls' frames, bypassing their treatment (DD + GG)?