Acoustic stretched ceiling : Worth it ?

[A Surfer]

What exactly is your thing?

 

[A Surfer]

I think I recall you being very intractable in another thread despite substantial evidence and well reasoned arguments being used to refute your very concrete position to the contrary.

 

[FrankW]

What exactly is your thing?

Valid, scientific evidence

 

[FrankW]

I think I recall you being very intractable in another thread despite substantial evidence

Fallibility of memory on your part and of course no link

 

[Adi777]

So, you want to tell, that acoustic treatment is BS? Or what?

 

[vicenzo_del_paris]

Let's not deviate from the orignal subject
The initial point was not not about double blind listening tests not about the look / quantity of absorber panels.
I should have been more precise in my request
I am interested about the impact, from a measurement standpoint, of an acoustics stretched ceiling (with damping or not) versus a regular stretched ceiling.
I am going to replace my current one anyway and I am wondering if the cost of the acoustic one will bring any enhancement, from a measurement standpoint.
If there is some, I will do it, otherwise I prefer not waste money. Then will it make make a listening experience change, that's an another point.

I was proposed this type of acoustic stretched ceiling.

Here are some absorption specs from concurrent solutions :

Regards,

Vincent

 

[vicenzo_del_paris]

I think most of us simply don't know. If it has a better absorption coefficient it probably has to help. Beyond that many of us probably don't have the knowledge to help out.

Sorry, if my post seems of no help. I didn't want you to think no one was paying attention to you.

In REW you can do the room simulation where you input the coefficients of absorption. Perhaps you can look up likely values for your materials and do one with and without the stretched acoustic ceiling. Some will be guesses, and you have what sounds like a not rectangular room. Even with this changing the ceiling from a low coefficient to a larger one would give you an idea how it effect things.

Arf, it seems that the room correction limits to 300hz ....

 

[Blumlein 88]

Arf, it seems that the room correction limits to 300hz ....

Yes, forgot about that. If you are replacing the ceiling anyway, I don't see how you can go wrong considering the structure you described. It will be a step in the right direction at least in my opinion.

 

[Vuki]

Do it. With glass/rockwool layer above. RT will drop significantly.

 

[Philbo King]

Let's not deviate from the orignal subject
The initial point was not not about double blind listening tests not about the look / quantity of absorber panels.
I should have been more precise in my request
I am interested about the impact, from a measurement standpoint, of an acoustics stretched ceiling (with damping or not) versus a regular stretched ceiling.
I am going to replace my current one anyway and I am wondering if the cost of the acoustic one will bring any enhancement, from a measurement standpoint.
If there is some, I will do it, otherwise I prefer not waste money. Then will it make make a listening experience change, that's an another point.

I was proposed this type of acoustic stretched ceiling.

View attachment 285827


Here are some absorption specs from concurrent solutions :

View attachment 285825

Regards,

Vincent

Fleece - make sure it is treated with borax (flammability concerns). A few cm would help, thicker would be better (depending on the frequencies you need to absorb). 2.5 cm would affect midrange ~1Khz and above. 5 cm would get down to ~500Hz and above. (Rule of thumb: halve the freq, double the thickness)
Although it might be more expensive, rock wool or fiberglass (rigid or roll) would be as effective and nonflammable. A decent 30 dB target decay time for a listening room is 400 mSec. (As shown in REW waterfall graph)

Your idea will really help if you have hard reflective floors.

 

[Tom C]

This seems to my inexpert eye similar to the drop panel type ceilings that had some popularity in the 1970’s. I think some called them acoustic panel. They consisted of a metal frame, and the square panels would drop into the frame to form the ceiling. Those were really effective at quieting a room, but probably had more mass than what is proposed here.

 

[DVDdoug]

The people who advocate for so called acoustic treatments in domestic living rooms will never ever offer the gold standard of perceptual science - double blind listening tests, to support any such belief. For obvious reasons. However, no one (except the actual blind) listen blind at home. So if one believes in such things, the sight of, for example, this type ceiling, could have an effect, most likely positive. "Worth" it is a separate question, probably only answerable by the user after the fact.

The most obvious reason is that it's impractical, if not impossible, to switch blindly between the two. And there probably be a WOULD be a difference in a blind test anyway and you'd probably know which is which.

However, no one (except the actual blind) listen blind at home.

That's not the point... The test should be blind to eliminate the effects of bias or expectation, and then after you've determined that you can or can't hear a difference and/or have a preference when you don't know what you're listening to. Your everyday listening doesn't have to be blind after that.

 

[Andrej]

For what it's worth, I once started building a "media" room, with 6" studs and only the outside (double walled + green glue in between) sheet rock walls. Then I started adding 5 1/2 inch thick rock wool to the walls and ceiling, first at the first reflection points, and then in other locations. With no furniture or people except for one chair and myself. Room was about 21 x 28 x 10 ft to the outside sheet rock layers. And I listened in the meantime, as more and more rock wool was added. It took well over a month. Initially, the sound was horrible. As I added more absorption, the sound improved drastically. At some point it was hard to perceive changes. At no point did I notice an often reported degradation with "too much" absorption.
Absorption can help with speakers which do not have consistent off-axis response, but most importantly (to me) it can drastically improve decay of resonances, in addition to the frequency response annomalies caused by those resonances. I found it much more significant to my enjoyment than any equipment change I did in my whole life. The only other thing that came close was changing speakers. YMMV

 

[Bjorn]

Hi all,

I am seeking some advice for my current listening room which is our living room (about 30 m2 – 7.5x4 and 2.5m height).
One side is mostly bay windows, and the back left corner is opened on the kitchen and the hall. Other sides are concrete walls.
We are going to replace our current stretched ceiling (old lacquered PVC one).
I was wondering if using an acoustic stretched ceiling (micro perforated, absorption coeff of 0.3) on its own or coupled with a 5cm layer of acoustic fleece between the concrete ceiling and the stretched ceiling (would probably end up with an absorption coeff around 0.6 or 0.7) would enhance the acoustics, reducing a bit reverbs on medium / highs or would not change anything.
Acoustic stretched ceiling is twice more expensive than regular one and adding the acoustic fleece layer is additional work/cost.
Given,the attached REW measurements (current measurement is the ‘kanta+sub+dirac’ in the mdat file), would you think it would worth it ? or useless ?

Thanks

It's going to reduce flutter echo and give some needed absorption. However, it's important to understand that a absorption coefficient of products is based on reverberation measurements, meaning it's only valid for very large rooms (concert hall size). The result will be different in a small acoustical space. The treatment wil be very bandlimited (altering the tonality) and will not attenuate apecular reflections well.

So certainly better than nothing, but not great treatment.

 

[SuicideSquid]

The most obvious reason is that it's impractical, if not impossible, to switch blindly between the two. And there probably be a WOULD be a difference in a blind test anyway and you'd probably know which is which.


That's not the point... The test should be blind to eliminate the effects of bias or expectation, and then after you've determined that you can or can't hear a difference and/or have a preference when you don't know what you're listening to. Your everyday listening doesn't have to be blind after that.

Frank is also misunderstanding/misrepresenting when it is necessary to blind test. Blind testing is necessary to tease out preferences between small differences, or to determine if a person who claims to hear something immeasurable actually can do this. If you have a clearly measured difference well above the threshold of hearing, it's generally not necessary to do a blind test to make sure that difference is "really" there. For example, if you have a room mode that's boosting 100Hz by 10dB and you're able to address it with EQ and room treatment and bring it down to flat, and you can demonstrate both with measurement, you don't need a double-blind test to "prove" anything. To say you need a double blind test to prove that someone can hear when a 100Hz signal is twice as loud isn't a commitment to scientific accuracy, it's just being obstinate.

As to the OP's original question, all things being equal, do the acoustic ceiling treatment. But the difference will probably not be dramatic, so if it's pricey, it might be worth spending that money elsewhere.

 

[Vuki]

It's going to reduce flutter echo and give some needed absorption. However, it's important to understand that a absorption coefficient of products is based on reverberation measurements, meaning it's only valid for very large rooms (concert hall size). The result will be different in a small acoustical space. The treatment wil be very bandlimited (altering the tonality) and will not attenuate apecular reflections well.

So certainly better than nothing, but not great treatment.

Exactly. Wall treatment, speakers&listening position optimisation still needed, but since it would be almost invisible - great

 

[vicenzo_del_paris]

It's going to reduce flutter echo and give some needed absorption. However, it's important to understand that a absorption coefficient of products is based on reverberation measurements, meaning it's only valid for very large rooms (concert hall size). The result will be different in a small acoustical space. The treatment wil be very bandlimited (altering the tonality) and will not attenuate apecular reflections well.

So certainly better than nothing, but not great treatment.

I am aware of that
The aim is not to build a a highly optimized treated room !
I will build a dedicated listening room with the next couple of years and I will take care of acoustics, especially in decay time

For the moment, we have to replace the stretched ceiling in our living room that I use as listing room and thus I am evaluating the ROI of a micro perforated one, trying to balance the supplementary cost vs potential benefit.

 

[Oristo]

I was proposed this type of acoustic stretched ceiling.

1. I am unfamiliar with that product; I do have experience mitigating noise leakage from e.g. offices repurposed for robotic testing to nearby occupied offices.
2. My best guess, based on seemingly thin material and peak effect at or below 500Hz is that primary effect is by acting as a lossy diaphragm.
3. In which case, adding a few cm of foam or fiber batting above it may only help spread that peak a little lower, depend on gap to concrete above (more gap is better).
4. Supposing intent is to improve some sound system, much depends on loudpeakers' vertical dispersion, which is often low.
5. Depending on crossover and driver arrangement, interference between tweeter and adjacent driver may cancel energy at first reflection point
   for frequencies at which treatment may be most wanted.
6. This wants measurements near first reflection point(s) to determine which frequencies there are prominent.
7. Such measurements want a so-called pressure zone or boundary microphone

 

[Philbo King]

If you want to go further down the rabbit hole, there is a page in this excel spreadsheet for working with panel perforation values.

Porous Absorber Calculator V1.60

This page also contains an online calculator for perforated panels

Porous Absorber Calculator

Note that a perforated panel in front of an absorber can make it become resonant (rather than wideband) depending on hole spacing, hole diameter, panel thickness, etc. You might try entering the values for the product you arr considering to see what its sound absorption spectrum will look like.

It's based on data from this book

Amazon.com

 

[Mr. Widget]

I have worked with a few different acoustics consultants on projects, but am not one myself. Part of what they offer in their design process is to generate reports showing the effects of the different treatments, but these reports also cost. From my experience with live rooms, adding a stretched fabric acoustic ceiling with 2" (~50mm) of absorptive sheeting behind it will definitely help, especially if you have a reflective floor.