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Dino99 05-22-2020 02:35 PM

100 mm Isover glass wool absorption panel or 50mm Isover+ 50mm air gap?
100 mm Isover/Rockboard 60 + air and sealed or? Problem is that the discussions on another forum was quite unclear and undetailed, as if one knew things in advance. So I have now specified the topic and my questions in detail.

Edit: See my shorter phrasing of the question at 10:14 am same day, although the details are here.

Which is optimal if I want to isolate and sound treat the living room where we sing and play, at the ground floor: TO not be heard by the neighbours (walls are concrete and seem good)? Already studied these links plus many other websites: Rockwool panel's distance from wall for best low freq. absorption . SO I think either 95 mm solid and no sealing or 45/45 sealed (dimensions of the Isover). Read my details and questions in the following suggestions:

1) 70 mm Isover/rockwool and 70 mm air gap? Someone wrote that it has to be sealed, so does it mean the frame contains both the airgap and the material? SO if 70 mm then 140 mm in total as th thickness of the frame. What does sealed mean and why do many hang them in the air floating without sealing them at the back as someone claimed, in order to get any effect? SOmeone said there would little to no effect if unsealed. I need to clarify what sealed means and if the wall is that seal?

2) 70 mm and 140 (or even 280) mm air gap behind like someone sugggested (can not post the curves yet). In my opinion the curve seems to be more flat when having the same measure of the material and the air gap. I would want a flatter curve but just no echo/flutter or bass that penetrates into the neighbour. The isolation is my first priority. In my opinion absorbing sound and converting sound into energy is similar to isolating the sound, just that then I hear less myself. SO well I prefer isolation and less dampening of the sound since then perhaps the equalisation needs to be adjusted if the dampening is unevenly distributed. Just my intuition.

I understand that some sound is preferable which is why I don't consider carpets. I mainly will cover the RFZ and other places in the ceiling with foam plates 50x 50 cm and 8 short 24 cm bass traps of foam: Apart from the 5 m wide floor to ceiling curtain (500g/m2), covering the entrance to the kitchen (adjacent to which are the neigbours bedrooms, beside and above), the kitchen door being behind me where I sing, and a big leather sofa in a 4x6 m room), little book shelf, tables, a door plus a glass door and a 120x120 cm window, just beside where I sing: HAve to stand and sing at one end of a rectangle and sing towards one of the long walls with the glass just left of me but with thin curtains and the glass door (plus kitchen door) covered by the heavy sound curtain). The curtain goes around in a corner: Bends.

Anyway how to hang them floating if the air matters? Or should I seal it and how: With what? If sealed then of course the frame ought to be just close to the wall. I thought: WHy not seal it with some double sided adhesive tape? SO the frame sticks to the wall. THe wall in itself is a hard material allowing for the pression absorption discussed.

3) 100 mm in a 100 mm frame and then 100 mm air gap behind (floating frame) OR one sealed frame of 200 mm (adjacent to the wall): Which however is heavy if I want to attach it with velcro that I already bought. Anyway if using velcro I would need to extend the frame to the wall at some point if floating. But it all comes down to this sealed issue.

In the other thread (another forum) someone said that unless sealed then the airgap would not matter. SO in that case why not just make it all solid material /Isover? That would be better right, instead of all that questionable air thing? Or seal it with the wall. Well I know air is good between two materials so ...

The wood dimensions I have at hand include untreated planks of ....

19x100 mm
47x200 mm
22x100 mm

I am considering 47x200 wood (with 100 mm Isover and 100 air inside and sealed by taping it to the wall or with velcro) OR 47x200 wood with 200 mm isover adjacent to the wall (attached with velcro /double sided tape) OR 22x100 wood (100 mm Isover unsealsed floating) OR 22x100 wood 45 mm Isover and 55 mm air sealed; OR 22x100 wood with 70 mm isover and 30 mm air, sealed by attaching it to the wall (or floating so the distance between the material to the wall gets 70 mm but then not sealed) OR 47x150 wood and as above (either solid 150 mm sealed (to the wall)or free floating with air (150 perhaps) or 70 Isover with 70 mm air inside sealed.

I remember to have heard that if open behind instead of placed close to the wall, then sound can also enter the frame from behind, thus contributing to the dampening of the sound. HOwever I think that that sound hits the wall and thus might disturb the neighbours anyway?
I know it is about isolation versus absorption. I have read too much. Now I need some clarity.

Txs for reading and hoping for some clarity, for which I will be grateful and help others.

Edit: See my shorter phrasing of the question at 10:14 am same day.

mhutchins 05-23-2020 09:59 AM

I had trouble deciphering what you are trying to accomplish. If you are asking what is the best configuration for a porous absorber, here is a link to a Porous Absorber Calculator that should be helpful in answering some of your questions. These are beneficial in addressing specific acoustical problems inside a room but do little to prevent sound transmission outside the room. To know which configuration you need, you really need to consider measuring the acoustic properties of your room with something like Room EQ Wizard.

If you are trying to quiet a single room in your home or office with the goal of your neighbors not hearing your activities, it will require that all of the walls, doors, ceiling and floors to be treated. Low hanging fruit are things such as air gaps beneath doors and air leaks around switches, electrical outlets and fixtures. Other things that readily contribute to sound transmission are communicating air ducts between rooms, air gaps between the wall and floor, light weight wall board with no insulation for partition walls, suspended ceilings with shared air spaces above. A good place to start is with a thorough understanding of the 4 key elements of soundproofing: Decoupling, Mass, Absorption and Damping.


Dino99 05-23-2020 10:37 AM

Hi Mike, sorry to hear you did not understand my detailed examples. I mentioned several examples to be sure it would be understood.

Tell me what you don't understand and we'll take it from there. It it the word seal you don't understand? DO you know what I mean with floating? DO you understand the principle of absorption due to an air gap? Tell me instead of telling me you could not decrypt.

I made a lot of examples to make sure it would be understood. SO you need to tell me exactly why not.

I always make my research profoundly before I ask, so I don't have a need to study all those things. I already did of course.

I need to see if someone can answer those simple questions I asked. Perhaps people are afraid from long posts but really it is simple and the examples explain this in details over and over again since repeating something improves the understanding, usually.

Dino99 05-23-2020 11:14 AM

Short version of the question:

There are no ducts, just in the bathroom. HOwever I am wondering whether the radiator won't transmit some sound.
I know that the bass is primarily dealt with by placing some bass traps in the corners between walls, plus using some absorption panels with a depth of at least 100 mm solid glass wool, stone wool or paper wool (if any of you ever heard about that): the new black, superior to the before mentioned materials when talking about sound isolation/absorption.

THe concrete ceiling and walls would be the primary medium for transferring sound. SO logically shielding the walls as much as possible would minimize that conduction/transmission of sound. The open doorway to my kitchen I talked about, I already covered with foam plus a sound curtain.

Furthermore I might hang up some traps out there or foam plates which I already ordered, although just 5 mm thick and 50x50 cm.

The ceiling I have covered with beforementioned foam plates of which I ordered 24.

SO we are down to the walls which is why I asked specifically about the absorption plates.

So to make the question short since evidently the long text did not help:

Say I need to make some absorption panels of 100 mm in thickness. SHould I buy frames that are 200 mm and then attach them close the the wall so they are sealed that way, and then have 100 mm of an air gap between the wall and the glass wool?

Or should I just buy frames of 100 mm thickness and hang them at a distance from the wall? I guess if the weight of the frames is not an issue then the easiest solution would be the frames of 200 mm.

As said, someone said that hanging them free floating away from the wall would not be a useful air gap. HOwever I have seen many do just that.

THose same people talked about sealing the frame at the back so there would be some air pressure absorption. They also said the membrane ought to be solid. Hence I figured to use the wall as the membrane.

SO 100 mm is my target (I have them at 95 mm from the store) and then I guess I should use 200 mm frames and seal them to the wall.

Or should it be open at the back and in that case I might as well use 100 mm frames and hang them 100 mm away from the wall, floating.


BIGmouthinDC 05-23-2020 12:30 PM

In the years I've been on this forum (now 17) I've never seen an answer to the questions you asked posted or even a link to another site where the answers might reside. The prevailing wisdom of this group is that there isn't an insulation product made that you can hang on a wall and successfully contain the sound from reaching your neighbor. Maybe you can find NRC data for the products and design you mention but that is for % of reflected sound, STC data is lacking.

Dino99 05-23-2020 12:45 PM

Actually when looking at these curves I might choose just 95 mm solid with 55 mm air gap, using a frame of 150 mm deepness. 200 mm is too much for our living room and probably not necessary.


Note Isover (green 95 mm solid) compared to the OC703 (blue 95 mm solid), which has been traditionally used. I use a resistivity of 10Kpa*s/m2= 10000 Pa*s/m2 for Isover and 23600 for OC703.

HOwever I might settle with 95 solid and a frame of 100 mm and perhaps hang it somewhat from the wall.

I tried to see 70 mm solid with 30 mm air with a frame of 100 mm, just hanging adjacent to the wall:


Note the green (70+80air) and the Blue (70+ 30air)! Big difference in absorption at the low frequencies while the blue curve absorbs more at higher frequencies and flattens more.

ALso compare the Isover Lamda 37, 70 mm + 30 mm air (BLUE) and the 95 solid (green) with Isover Lamda 37, 95mm + 55 air (RED). Much higher absorption of the lower frequencies for the Red, but see how the blue and green absorb better from 450 HZ to 1200 HZ.

If you compare Isover Lamda 37, 95mm Solid (green) with the Isover Lamda 37, 70 mm + 30 mm air (BLUE) they are quite identical but the green (solid) is a tat better absorbing for the lower frequencies and in the range 1000 -2000 Hz.

The reason for my chosen thicknesses is the dimensions of the frames at disposition.

This will have to do since I don't intend to build a room inside the room: I would buy a small metal cabinet for that if I chose to, then cover it with blankets. Then it would be isolated due to being completely covered. If we talk about covering the walls and ceiling instead, I believe I can minimise how much will travel through the walls by covering as much as possible of them. THis way I will also minimize the echo and hence resonance. Well I do believe that due to say the glass and deflection of the sound in the Isover we also have some insulation of the sound, as opposed to the case when using foam which in my opinion doesn't do much but treats the sound a bit.


Addition: I decided to zoom in on the 95 mm Isover option with various air gaps.

BIGmouthinDC 05-23-2020 03:14 PM

from Wikipedia "The voiced speech of a typical adult male will have a fundamental frequency from 85 to 180 Hz, and that of a typical adult female from 165 to 255 Hz. Thus, the fundamental frequency of most speech falls below the bottom of the voice frequency band as defined above."

Look at your graphs at that range.

Dino99 05-23-2020 03:24 PM

I think you just posted. I in fact have just added another set of curves since we had the same idea :-) I found this

The voiced speech of a typical adult male will have a fundamental frequency from 85 to 180 Hz, and that of a typical adult female from 165 to 255 Hz. Thus, the fundamental frequency of most speech falls below the bottom of the voice frequency band as defined above.

Here is that new set again: http://www.acousticmodelling.com/mli...&s42=1&d42=105

So I'd choose the 95 mm + 55 mm air which fits with the plank at hand (150 deep). I might even tilt it: SOme idea I saw someone mention somewhere. If one tilts the panel away from the wall at the bottom while being fixated to the wall at the top, this will both increase the air gap but also increase the distance through which the sound waves travel inside the material (glass wool) so this will lower the speed of the sound even more, meaning the air gaps needs to be even less to absorb as well (with the peak at a lower frequency). But I am speaking about sound waves arriving perpendicularly, 90 % at the panels.

THese are details.

And yes you are right, it is exactly the vocals that my neighbour could hear one day too late (forgot the hour) from their bedroom. He said he doesn't hear the music and I always try to turn the music as much down as possible to hear the nuances of my voice when singing. SO I think I don't need to break down the walls to rebuild them.

BIGmouthinDC 05-23-2020 03:37 PM

please come back and report your results.

Dino99 05-24-2020 12:24 AM

I will.

I tried to find the nrc for Isover and got one of 1.0 for 80 mm as well as 100 mm thickness at a resistivity of 12.3 kPa. at 60 mm thickness it read 0.95. https://www.e-isover.cz/data/files/i...-tl-en-731.pdf

TO compare I found some values for Roxul Rigid Rockwool here: https://www.bobgolds.com/AbsorptionCoefficients.htm
The NRC reads 1.05-1.10 at 100 mm of thickness depending on the density.

The STC values I haven't found (like I think you mentioned there are none since it is considered an absorption material right).

I looked the definitions up:
NRC is only the average of the mid-frequency sound absorption coefficients (250, 500, 1000 and 2,000 hertz) rounded to the nearest 5%. The Sound Transmission Class (STC) measures the sound transmission between spaces. ... A higher STC rating blocks more noise from transmitting through a partition.

Another: The NRC or Noise Reduction Coefficient of a surface represents its ability to absorb versus reflect sound. ... For example, if the NRC is 0.70 this means that 70% of the sound waves entering into the material will be captured and converted, while 30% will reflect back out of the material into the room.

How to interpret density values (Some info about resistivity in relation to density) found here https://www.gearslutz.com/board/bass...er-sweden.html:

There is a relationship between density and air flow resistivity, but it is loose, very non-linear. Generally, denser products means higher air flow resistivity, but with the same density, glass wool products will typically have higher air flow resistivity than stone wool products, and there are large variations in the density/flow resistivity correlation within these two main product groups, generated by other factors. A very rough understanding of the relationship between density and air flow resistivity can be derived from density/flow resistivity correlation graphs provided by the manufacturers. I have these numbers from Rockwool, Isover, and from an independent Norwegian construction research institution (Byggforsk):

Air flow resistivity -------------------- : 5 kPa*s/m2 - 10 kPa*s/m2 - 20 kPa*s/m2 - 30 kPa*s/m2 - 40 kPa*s/m2 - 50 kPa*s/m2
Rockwool stone wool products: ------------- : 9-31 kg/m3 ----- 24-49 kg/m3 ----- 36-75 kg/m3 ---- 47-98 kg/m3 ------ 56-120 kg/m3 --- 64 -130 kg/m3
Isover stone wool products: ---------------- : 27-40 kg/m3 --- >50 kg/m3 ---------------------------------------------------------------------------------------
Unspecified Nordic stone wool products --- : ------------------- 32-37 kg/m3 ----- 38-52 kg/m3 ---- 53-65 kg/m3 ----- 70-80 kg/m3 ----- 80-90 kg/m3
Isover glass wool products: ---------------- : 9-18 kg/m3 ----- 15-30 kg/m3 ----- 27-45 kg/m3 ---------------------------------------------------------------
Unspecified Nordic glass wool products --- : ------------------- 13-27 kg/m3 ----- 33-45 kg/m3 ---- 47-58 kg/m3 ----- 65-75 kg/m3 ----- 75-85 kg/m3

Note: The graphs are hard too read with any accuracy, so don't take the numbers too seriously. But if you are interested in this, there are more information in the graphs than in the numbers displayed here. Be aware that when a manufacturer estimates the performance of competing products, it will be portrayed as "bad" as reasonably possible.


In this link there are some links to graphs as well.

Dino99 06-03-2020 04:35 AM

Update: I decided to go with the 4,5 cm thick frames /planks and just use some towels I have already since cotton absorbs well and since I will use the base traps mainly for the lower frequencies.
I have learned that first one ought to experiment with dampening the lower frequencies by using base traps. Then one can add a sufficient amount of panels for the higher tones and thus they need not be that thick which is more practical.

ALso one can tilt those thinner panels according to taste and test the curve of the sound over a broad spectrum. If tilted or removed somewhat from the wall their will be more absorption of the low frequencies.

Hope this inspired some anyway.

BIGmouthinDC 06-03-2020 05:05 AM

Just an observation, my training suggests that planning the room, placement of subwoofers and seating is the first step of managing bass response at the listening positions. Not building absorbers. Tell us about your room.

Dino99 06-11-2020 11:55 PM

Hello Jeff,
Unfortunately it is rather bothersome to optimize where I stand and sing or play the piano, since THe rectangular room has a giant sofa and there is no easy way to place the loudspeakers oriented along the long side of the room. If doing so I would have to place the piano in the middle of the room and the loudspeakers in front of the windows and the dining/working table would be kind of blocking things.

As things are now, I have the piano and the loudspeakers placed at one of the long walls (5,75 m approximately whereas the short wall/window + glassdoor is 3,5 m) with the window to the left 40 cm back from the corner. I then stand at the other end of the long wall with an open kitchen door behind me covered 4 cm think foam curtain (to be replaced with a noise cancellation mat for isolating cars etc. just 0,5 cm think), plus there is the mentioned 500 g/m2 stairville curtain in front of the kitchen door behind where I stand and sing, which is 5 m long and covers the glass door to the left as well (going around in the corner). I then control my pc on the table placed in front of me in front of the piano.

As I remember then one should optimally be singing along the lengtitude , the loudspeakers being placed somewhat (a feet at least) away from the wall and one ought to stand in the spotlight of the soundwaves. When I chose loudspeakers I chose some without the base located in the back, in order to avoid the problem with the base going directly into the wall. ALready this is a big advantage. BEsides I chose not to have a subwoofer, partwise for the before mentioned reason since then the base comes right in your face anyway) and also to avoid problems with the neighbours plus the hazzle of carrying such big block around.

THis is one of the many sites I found throughout my research about the topic. DOesn't it look interesting?


I discovered after 1 month that the 24 foampanels from WISH had not even been sent and was not in store, so I required a refund of the money. Instead I tend to focus on THE PLACEMENT THAT YOU TALK ABOUT PLUS Base traps and the 5 Panels that I will make myself. Just ordered the prints for the walls. THey are up to one meter wide and 75 cm high. THe material is towels and the thickness 4,5 mm and I will just settle with putting some nail at the bottom in the frame to make it float and get some airgap.

I also am awaiting some door sealer and door sweep for the entrance door from the livingroom/studio to the hallway, which is connected to the bedroom and the main entrance.

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