Does sound-absorbing material placed behind the ceiling gypsum board have the effect of absorbing low frequencies?

[ww1]

Because there is no independent audio-visual room, a home theater is built in the bedroom. Because of the need to consider daily life, too much acoustic decoration cannot be done on the surface. Is it useful to put sound-absorbing materials in the ceiling gypsum board, or must the sound-absorbing materials be made on the surface?

 

[rdenney]

It depends on the objective. If the object is to soundproof the room to avoid annoying those in adjacent rooms, then there is value in doing stuff behind the drywall. But it's less about absorption and more about decoupling. I don't see my opportunity to add what what you already have--concrete walls are already massive enough to block transmission well enough. The ceiling is already hanging by wire, which doesn't decouple it fully, but does help.

For reducing interior reflections, no, adding stuff behind the drywall will have no effect. Reflections are about surface shapes, and drywall is smooth and hard. Treatments work by providing traps that reflect acoustic energy into dead-ends where they can be attenuated with soft materials, and the shapes of those traps govern the frequencies they damp. I would focus on furniture items that break up the reflections of interest, but the ceiling will be difficult to deal with in that regard.

By the way, I can't make the photo and the plan correlate.

Rick "reverberation isn't bad; echo is" Denney

 

[Bjorn]

Gypsum isn't a very good material in front of porous when the goal is bass absorption. But it's not like it's not going to work either.

 

[Vladimir Filevski]

With gypsum panels It will have some effect on low frequencies, but nothing in mid and high frequencies.
There are other panels with excellent absorption down to 100 Hz:
https://knauf.com/en-MY/p/product/heradesign-r-superfine-a2-25mm-27156_0240

It is important not to overdo the absorption,. There area some internet on-line calculators for calculating optimal reverberation vs absorption, but this is really job for an expert.

 

[DVDdoug]

I'd expect it to do very little. It's only going to help with whatever goes-through the wallboard and is reflected back.

But it can't hurt and it should help to reduce the sound getting-through to the room above.

 

[NTK]

Below is from Dr Toole's Designing a Home Theater Part 1 (you can download the files following the links at the top of the web page). Ceiling gypsum boards that are allowed to vibrate (not rigidly attached to the concrete) will be able to absorb low frequency. A large area will help a lot. Damping materials behind the boards probably don't do much. The idea of damping materials behind membrane absorbers is to help dissipate the vibrational energy, which I don't think would be necessary here with the relatively heavy gypsum boards.

Sound Reproduction

A Routledge Companion Website

routledgetextbooks.com

 

[dedobot]

Gypsum board on metal construction is the the worst of everything for sound.
My back wall literally rattled until I put (with glue and screws) very thick and density rubber (3.4kg per sq.m) at the gypsum.
It wasnt easy and wasn't cheap. About the ceiling- I dont know ,sure you will need a reinforced construction to cope with the rubbers weight.

 

[Timcognito]

Spring-Loaded Screw Turns Drywall Into Sound-Absorbing Panels

I was going through bookmarks and found this. It may be help for people with speakers (I just do headphones, have neighbors on both sides with a townhouse). If you're use these with Quietrock, which absorbs 7 times more sound than regular drywall you might get some good results. I've hung...

www.audiosciencereview.com

 

[CINERAMAX]

You could use sound absorbing plaster on your ceiling and it helps a lot. Baswaphon.

 

[dedobot]

You americans usually use wooden supporting structure in domestic applications , its magnitude better and not comparable with this thin metal profiles at OPs photo (and in my home).

 

[kyuu]

If you want a gypsum wall surface to absorb bass frequencies, the best thing to do would be constrained layer damping: use two layers of the gypsum with some green glue or mass-loaded-vinyl sandwiched between it. I believe Dr. Earl Geddes touted this construction method, if I recall one of his presentations correctly. You'd need to ensure the supporting structure on the ceiling could handle the weight, of course.

 

[Thomas Savage]

If nothing else , when they screw the board up in that room have them screw it to code but also glue it along all contact areas. Stronger, less shake rattle and roll .

After that see how you feel , it would be trival DIY to add some acoustic board later or light acoustic treatment. https://www.british-gypsum.com/products/acoustic-ceilings/gyptone-quattro-41#characteristic

Absorbing bass , I'd measure the room first then see what you actually need but yes might as well put some rock wool behind the boards , won't hurt , again cheap as chips so why not . Doubt it will be absorbing much bass , possibly add delay , not my wheelhouse.

 

[bigguyca]

Because there is no independent audio-visual room, a home theater is built in the bedroom. Because of the need to consider daily life, too much acoustic decoration cannot be done on the surface. Is it useful to put sound-absorbing materials in the ceiling gypsum board, or must the sound-absorbing materials be made on the surface?

- Pictures deleted -

Suggested installation:

1) One layer of drywall on the ceiling.

2) Fill the space between the drywall and the concrete ceiling with fiberglass insulation

Sound will travel upward through the drywall and be partly absorbed broad spectrum by the approximately 12-inch (30cm) thick fiberglass layer. The broad-spectrum sound absorption is a very nice feature of this system. Some sound will of course be reflected from the ceiling drywall back into the room.

Some sound will then travel upward through the concrete, much of the sound will be reflected downward by the concrete.

Broad spectrum sound will be absorbed on its way back down toward the ceiling drywall, some sound will be reflected by the drywall back into the fiberglass to be absorbed. A very reduced level of sound will move downward through the drywall back into the room.

3) The room appears to be part of a large concrete structure. The structure will absorb and transfer vibrations from impinging sound, direct vibration transfers from equipment such as refrigerators, HVAC, washers and dryers, exercise equipment, and impacts mostly on floors, from all parts of the entire structure. Some of these vibrations will be transferred to the air below the concrete ceiling as sound and proceed downward. The fiberglass layer will absorb much of this likely low frequency sound.

4) Much of the sound that enters the room from the walls and windows will hit the ceiling where a portion of this sound will be absorbed by the insulation in the ceiling. The concrete box that is the room will encourage sound to build up at various frequencies. The ceiling absorption should significantly reduce these buildups.

 

[Audio Science Pal]

Does sound-absorbing material placed behind the ceiling gypsum board have the effect of absorbing low frequencies?​

Yes. I would install Rockwool.

 

[theREALdotnet]

Plasterboard (a.k.a. gyprock, etc.) becomes quite transparent to very low frequencies. Whether there is any point in putting absorption on the other side depends on what's beyond the plasterboard. If it's just another plasterboard wall then from the point of view of room treatment you're set. Just let whatever makes it through leak out into other rooms and you won't have to deal with it in-room. From the point of view of noise (and thermal) insulation it would be wise to fill the gap with absorption material.

Given that only very low frequencies will readily go through plasterboard (depending on thickness, spacing between joists, fastening method, etc.) you may need some in-room absorption anyway.