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Discussion Starter #1 (Edited)
During the installation of my home theater Ceiling (Drywall), with no soundproofing materials above it, since it is in the third floor with nothing above my HT, I tried to test it by pounding the ceiling with my fist everywhere, and i did notice some sound coming from the suspension in some areas. so i got worried that i might hear the same thing during some heavy action movies!

The contractor (obviously) says that there is no way I could hear that during the movies because pounding has different affects than what big Subwoofer or LF, and there is nothing else to be done for the ceiling as they are properly installed with nothing loose or something. but i dont really want to take that risk as i have OCD with things that rattle in my room during movies!

So I need to test that because removing the drywall and re-doing things again now will be much easier than later.

What would you advise me to do, should i bring my laptop and try to run sine wave to test it first, but keep in mind i have to bring my laptop "loaded with REW", AVR, & Subwoofer, connect them in unfinished and empty room to test the rattling because pounding test gives you a good indication of any rattle issue? or what my contractor says is correct?

to give you an idea, check the photos below which show you how the drywalls are hanged (which i believe were properly installed) and the second photo shows at what stage is my drywall now.


Thanks and appreciate feedback to sort out this issue
 

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Discussion Starter #4
I have zero experience with that suspension method, is that single or double layer of drywall that you have on the ceiling. I think you are going to need to test it to be sure.
BIGmouthingDC

is it easy to remove the drywalls now at this stage to fix the rattling issue by just unscrewing the joints? or some cutting and breaking required?
 

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my best guess looking at the picture of how the drywall was hung, the fact that it is a low mass structure, the fact that it is wide open above with no sound proofing measures is that the ceiling will vibrate if the room is sealed air tight and if you have sufficient subwoofer power, Will it cause rattling noise from the structure above? - can't be predicted. Will it leak sound through the surrounding walls? - absolutely. Sound doesn't travel only in straight lines in this case just up. The drywall is probably screwed in place so you could demo the room and start over $$$. You would need to replace the drywall. it would be too messy to reuse. I would have done double layers of 5/8 drywall with Green Glue dampening agent between layers.

I'd say bring in your gear and test it.

Looking at the suspension system I'm not sure how you would even FIX any rattling issues.
 

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Discussion Starter #6
my best guess looking at the picture of how the drywall was hung, the fact that it is a low mass structure, the fact that it is wide open above with no sound proofing measures is that the ceiling will vibrate if the room is sealed air tight and if you have sufficient subwoofer power, Will it cause rattling noise from the structure above? - can't be predicted. Will it leak sound through the surrounding walls? - absolutely. Sound doesn't travel only in straight lines in this case just up. The drywall is probably screwed in place so you could demo the room and start over $$$. You would need to replace the drywall. it would be too messy to reuse. I would have done double layers of 5/8 drywall with Green Glue dampening agent between layers.

I'd say bring in your gear and test it.

Looking at the suspension system I'm not sure how you would even FIX any rattling issues.
I will then test it today and see if things get rattled. and will report back here.

As for sound leakage, I did put RC & Drywalls along with fiberglass .etc on the walls except the ceiling, and above the drywalls there is concrete which i guess would help to soundproof the room a bit. in addition, the room is fully surrounded by bricks & plastering with a total width of 13 inch (19 inch with drywall & RC .etc)

note that the HT surrounded by store room, living room & streets (it is located in the corner of my house). and my target was to stop the sound coming into the room which it looks good so far.
 

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If you have neighbors, you may also want to worry a little about the sound that gets OUT.
;)
Might be a good idea to "treat" the ceiling, anyway.
Michael
 

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Discussion Starter #8
If you have neighbors, you may also want to worry a little about the sound that gets OUT.
;)
Might be a good idea to "treat" the ceiling, anyway.
Michael
the nearest neighbor is approx. 45-50 ft away, and the ceiling is solid and heavy concrete.

but if putting insulation can resolve the rattling issue, i will defiantly do that!

anyway i found the issue, and will post it now to see if you guys can help in such case.
 

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Discussion Starter #9
I'd say bring in your gear and test it.

Looking at the suspension system I'm not sure how you would even FIX any rattling issues.
I did the test test using Sine Wave generator and 200w subwoofer.

at specifically 58hz (with spl reads 80db), the ceiling did vibrate and there was some sound or buzz noise coming, and if i push the ceiling, the vibration/rattling goes away! And i noticed the rattling comes only when i place the subwoofer in the left corner!

check out the video i did while doing the testing: https://www.dropbox.com/s/4o4l46m41h4emik/test.MOV?dl=0

I will defiantly remove the drywalls now, so any suggestion would be really appreciated on what's next
 

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Discussion Starter #11
my best guess looking at the picture of how the drywall was hung, the fact that it is a low mass structure, the fact that it is wide open above with no sound proofing measures is that the ceiling will vibrate if the room is sealed air tight and if you have sufficient subwoofer power, Will it cause rattling noise from the structure above? - can't be predicted. Will it leak sound through the surrounding walls? - absolutely. Sound doesn't travel only in straight lines in this case just up. The drywall is probably screwed in place so you could demo the room and start over $$$. You would need to replace the drywall. it would be too messy to reuse. I would have done double layers of 5/8 drywall with Green Glue dampening agent between layers.

I'd say bring in your gear and test it.

Looking at the suspension system I'm not sure how you would even FIX any rattling issues.
Thanks for your advice, as i have tested the room and found the ceiling is the weakest point in my room.

I will start removing the complete ceiling, and do it all over again in a proper way (DD, GG .etc.), because i felt the ceiling was like a huge drum above my head!

there will be some challenges doing the proper ceiling especially with the ducts going through in some areas, but we will manage it hopefully.

to summarize:

1- mass is required by having DD & GG
2- insulation is required to stop the resonating and preventing drum issue.
3- wooden framing structure


will start that tomorrow as i could finally find GG near my area :)
 
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