Soundproofing Storage Room (concrete box) to Convert to Home Theater

[orenharel]

Sorry, I just wasn't sure if anyone saw my reply so I was checking just in case.

I think that I am learning a lot thanks to you and others so far, so I am feeling closer to the confidence level I need to begin the project.

So to summarize and make sure that I understand correctly (sorry for the length!), please tell me if you agree with the following conclusions:

1) Walls - Although certain materials improve STC ratings when inserted into a cavity of a wall, some of these materials actually have a high NRC rating when exposed (i.e. when not behind a solid reflective material). Regular 2.5" fiberglass insulation batts for example don't have an STC rating but have an NRC rating of 0.9-1.0, making it more effective than the typical foam-based sound absorbing material, not to mention a much a cheaper alternative. In my situation, as the fiberglass batts (or cotton-based ones you mentioned) will be located between the concrete wall and the heavy curtains (which are absorptive rather than reflective), the combined NRC values of the curtains and fiberglass batts should suffice for my sound absorption purposes. This coupled with the sound blocking properties of the brick/concrete walls should probably cover my total soundproofing needs.

2) Doors – Two solid core doors on the same door frame with wether stripping around the inner part of the frame to seal them properly is the best way to go rather than dealing with hollow core doors. The faces of the solid core doors are reflective, therefore two things needs to be done: i) the surface of the door facing the inside of the room needs to be covered with sound absorbing material to avoid sound waves reflecting back into the room and; ii) if the two doors are less than 2” apart (or even 2.5” as in my case) a resonance chamber will be created, and therefore sound absorbing material will be needed to fill in this space.

Did I get it right? 

By the way, regarding the process I discuss in point 1 above, do I still need to worry about an excessively “dead sounding” room or would this still be O.K.?

[Randy S]

1) Agreed, as long as you do not exceed certain db, sp levels and lets not forget frequencies under 125hz.
I would like to explain this to you in further detail, so that you can have a true understanding on how acoustical conditioning is addressed.


2) yes, and you can use SSP foam mat for this.
 
Give me a call when you get some time, here is my contact info.

Randy S.
760-752-3030 ext 104

[orenharel]

Hi Randy,
Sorry, just a quick follow-up question to our discussion. Regardless of whether I use cotton-fibre or fibreglass batts as my sound absorption material on the walls, would 2.5" thick material be sufficient (especially since the curtains in front of it will do part of the work) or is it still recommended to go at least 3" thick?

Also, I have read online in a few places that dense styrofoam (i.e. or basically any generic polystyrene foamin sheet form) has even greater sound absorption ability (i.e. higher NRC rating) that cotton-fiber or fiberglass - is there any truth to this or is it just a myth? If true, is it therefore an even cheaper and more effective alternative? Yes, my questions are always complicated, sorry...

Thanks again for all your help!

[Randy S]

2.5"-3" shouldnt be a noticable difference, remember placement.

Im not buying in on the styrofoam myth...sorry...thermo sure...