Sound absortion/deadening

[racerxnet]

I am remodeling the basement and have to work with the existing structure (to a point). What can I do to control the sound traveling to the other parts of the home. One wall has access to the studs from the drop ceiling and I can fill with blow in insulation (or other material). The other has no sheetrock on the back side and can be filled with what may work best. I thought that tire crumbs might be a good choice as well as insulation, foam, or other products. I cannot build a room in a room to isolate, so I am limited. The wall is on 16 inch centers with 5/8th sheetrock.

This room will serve as my 2 channel audio and home theater. Can some of you recommend some ideas to help isolate my room.

Thanks,

Mark

 

[Al M.]

Perhaps this material is useful:

http://www.acousticsciences.com/products/wall-damp

I don't have experience with it in walls, but it is part of my ASC Window Plugs that do a phenomenal job in sound insulation and acoustic improvement of my room.

 

[amirm]

Filling the cavity while a good idea, will not do anything to absorb sound. The biggest problem is low frequencies. If you can't build a room within a room the next solution is to put in "hat channels" and isolation grommets. Unfortunately most builders don't know how to do this and all it takes is a single screw to mess up the mechanical isolation. You will also have to seal every opening. Even small gap around outlets can let through a ton of sound energy.

 

[JackD201]

For airborne sound transmission I recommend magnetic fridge gaskets on your doors. Vinyl industrial barriers is the standard go to in cases where room within a room construction isn't possible. Al's suggestion looks very cool. This is the first I've seen it. It's basically what I've mentioned earlier but is modular and easy to install. Not cool, way cool. The Low frequencies will travel through the densest materials and try to find their own paths so "breaking the circuit" is a wise move. Instead of the typical rubber feet, you can rest the subs on absorptive mats or sprung stands. I believe Auralex makes pads for subs.

If you are redoing your floors with engineered wood, some companies provide a damping substrate to go with their planks. Some even incorporate them in the design. Use these instead of ply or sheetrock to interface with your slab. If you have a turntable, don't use these under that area.

Hope this helps. Enjoy the build Mark!

 

[Al M.]

Filling the cavity while a good idea, will not do anything to absorb sound. The biggest problem is low frequencies.

The WallDamp material that I referred to addresses this. It absorbs low frequencies.

 

[amirm]

The WallDamp material that I referred to addresses this. It absorbs low frequencies.

That's what it says but it has no technical measurements to show the level of absorption. The material is viscoelastic which is the same as green glue. Putting that between two sheer walls does provide that absorption but its application between the stud and wall is news to me. If there is measurement that shows it to work, I will sign up. Until then, I will wait .

Here is an example of what I am talking about:

Addition of hat/resilient channels improves low frequency absorption. Even then note how little absorption exists compared to above 500 Hz. It is very hard to block low frequencies.

 

[JackD201]

Given the particular situation

a. basement
b. avoid sound getting out as opposed to sound getting in

a. midbass and above is not much of a problem and seals will do unless the floor above that is also your ceiling slab is not concrete slab. If that is the case, that makes for a strong case for both mass and energy transfer absorption (a lot of rockwool + barriers).

b. Only room within a room will deal with bass transmission directly. Thanks for showing the chart as this illustrates it nicely. Now, there are indirect ways to deal with amplitude. For example use of such damping materials tame the wall flexure and resonances that later feed/release the vibrations through the studs. Increasing the number of contact points to the wall material also effectively stiffens the wall structure itself and raises the resonant frequency of transmission. In this scenario, pads like this and products like green glue become even more effective. Every little bit helps and it isn't meant to be a replacement for the channel clips. It's just additional help. Since the most offensive range for other family members or even the neighbors is typically between 50Hz and 30Hz, the dreaded drone, this is where I would start. Look for points of direct contact like the subs and the main speaker to the floor and deal with that first.

 

[Al M.]

That's what it says but it has no technical measurements to show the level of absorption. The material is viscoelastic which is the same as green glue.

A call to the factory should settle the issue to the potential customer.

 

[racerxnet]

Thanks to all who have replied. Unfortunately, I have a wall that is already sheetrocked on both sides. I am looking for some way to dampen the wall without replacing the existing sheetrock by adding fill between the studs. Access is through the drop ceiling panels. That would be my main focus right now. Have a Merry Christmas!

MAK