Vibration Issue

We are in the testing phase of the Voice Over studio we just built. Our design consisted of a room within a room... the control room is approx 96"x96" and the vox is approx 48"x96" the 2 rooms are built separately and are encased within another room. The floors are on neoprene pads, sitting on a wood floating floor. we have 2 pieces of 3/8 glass. We can scream in one room and hear nothing in the other, but when we tap on the floor, or knock on an un padded section of the wall... the mic picks up quite a bit....when we play low end, it picks up to....so what can we do to stop this vibration.. I was told over and over the room within a room would do that. any suggestions? Thanks!! Pete p.s. Location: Sarasota, Florida

welcome! please update your profile with your location. what you have is either a short circuit in the isolation walls - that is something is making contact between the assemblies and transferring it, or your isolation on the walls and ceiling are good but the floor is your flanking source - likely your walls are coupled to the floor and the airborne sound from your voice (which isn't necessarily a very high energy source compared to a PA speaker driving 110db) isn't enough to trigger the transfer but the actual mechanical contact clearly is. one option would be to test very carefully and determine the actual path the sound is taking. if its a short circuit somewhere (wood or metal, or tightly packed insulation) then you''ll have to break that. if it's flanking through the floor, you might have the option to put in a damped floor in the booth and/or CR to isolate the mic etc from the floor.

phansen1 wrote:

We are in the testing phase of the Voice Over studio we just built. Our design consisted of a room within a room... the control room is approx 96"x96" and the vox is approx 48"x96" the 2 rooms are built separately and are encased within another room. The floors are on neoprene pads, sitting on a wood floating floor. we have 2 pieces of 3/8 glass. We can scream in one room and hear nothing in the other, but when we tap on the floor, or knock on an un padded section of the wall... the mic picks up quite a bit....when we play low end, it picks up to....so what can we do to stop this vibration.. I was told over and over the room within a room would do that. any suggestions?

Your issues only get worse from here since you have a control room that is square to look at and most likely cubed...with an 8 foot height...your isolation booth is multiples of each other....it's a wooden structure...your asking at the wrong end of the build....you should have asked before it was done because the easy answer is tear it down an d start over.

Also what calculations were made when "floating" the floor? Is the neoprene a store bought product or something you have cut down? What is the total weight of the room sitting on these pads. Under the studio flooring is it concrete? Did you use any sway braces or ceiling braces? ...and what weight insulation wool has been used between the seperate rooms and is it overly compressed Can you post the plan and some photos? ta lil

Hi Pete. Welcome!

I was told over and over the room within a room would do that. any suggestions?

It will, if you do it right! So maybe you didn't actually build it right? It's hard to tell without seeing your plans, or photos of the build in progress. Or both. Please post those, so we can take a close look and try to figure out where your problem is. From your description there are several major issues that stand out, as others have already mentioned. First, as Brien said: your control room is square since both dimensions are 96", and probably even a cube if the height is also 96". That is about the worst possible shape for a control room. All of your modes, in all three axes, are piled up on top of each other. You have pretty much the same situation with our booth: 96" is exactly twice 48", and once again if you have 8 foot ceilings, then you have multiple harmonics of modes piling up. It might be the case that the rooms are tuned to each other due to the major coincidence of dimensions, and are resonating sympathetically. I can't see how it will be possible to treat such rooms in order to make the usable, even if you can resolve the flanking problem. If I were you, I'd tear down the dividing wall and move it a few inches , plus raise or lower the ceilings in one or both rooms, to get close to one of the know good ratios. Next, as Lilith said, you say you have floated your floors, but you probably did not do so correctly, so they are not actually floating at all, which would explain the flanking problem that you have. If you do not float exactly right, then you did not float at all, and therefore your floors have direct flanking paths to each other. This would be my guess as to where your problem is. Floating a floor successfully requires a huge amount of mass and careful calculations to get it right. Take a look here to find out more about this subject, then let us know if you did all of that: viewtopic.php?f=2&t=8173 http://www.nrc-cnrc.gc.ca/obj/irc/doc/p ... /ir802.pdf Finally, you didn't mention anything about the construction techniques that you used, such as they type and thickness of materials on each leaf, the depth of the air gap, the amount of insulation, the way you did your HVAC ducting, how you sealed your doors and windows, etc. It might just be that you don't have enough mass in your walls, or that your air gaps are too narrow, or there isn't enough insulation in the cavities. All if those will raise the MSM resonance to a point where low frequencies are transmitted well while higher frequencies (such as screaming voices) are still isolated well. What frequency did you tune your walls to? And what frequency did you tune your floors to? If you can provide all of the details of how you built it then it shouldn't be too hard to figure out where your problem is, and how to fix it. So to start, please post your plans, photos of the build in progress, the calculations for your MSM resonance, the calculations for your floated floors, and the construction details (materials, dimensions, etc.), plus all the details that Lilith mentioned. My bet is on the floors not being floated right, but we'll need all of the data to figure it out for sure. - Stuart -