Home theaters and recording studios are sound isolation projects that have to deal with alot of low frequency noise. Because of this high low frequency content, the STC rating (which ignores low frequencies) is not a good barometer of performance.
To gain an idea of how far typical theater applications and deviate from the assumption inherent to the STC system, we view the response measured in an actual theater compared to the assumed noise source for STC.
A typical home theater, playing a scene from an action movie very loudly. The enormous low frequency content is apparent. Sound levels peak at 40Hz, and remain strong to 20Hz (the lower limit of this measurement).
Now, this is a loud theater, with a healthy pair of subwoofers, and may be viewed as falling on the higher extreme, but the strong low frequency content is typical of modern theater situations - low frequency noise must be dealt with.
Well, as we have to deal with low frequency noise, we may as well get started.
The Green Glue Company has measured the full-range performance of a wide variety of walls at Orfield Laboratories. By measuring all the walls in the same laboratory, in the same conditions, installed in the same manner, a good assessment of comparative low frequency performance can be made. The results of this work - and the lessons that it teaches - can be found in our document "Understanding the low frequency performance of walls".
Low Frequencies are Green Glue's specialty
This work outlines very clearly the considerable low frequency advantages that Green Glue can offer in many types of walls - the reduction of resonance problems due to the damping effects of Green Glue allow stud walls with low frequency performance higher than ever before. Green Glue can also turn the lowly conventional 2x4 wall into a very good wall indeed.
Particularly of interest is sound quality within a room or as least as important as sound isolation for many situations, we offer perhaps the largest formal study on the sound absorption of walls to date. We hope you enjoy it, and find it helpful to your situation.
These documents may also be of aid:
1. Understanding Sound Isolation - Steps you through the basics of soundproofing
2. Sound Isolation of Doors - Takes a look at how to attain good performance from the entrance to your rooms,
3. Sound Isolation and Windows - Particularly relevant to studios
4. The Sound Absorption Properties of Walls
5. Understanding STC - An exploration of what STC is, and what it isn't.w
6. Sound Isolation and Windows - Particularly Relevant to Studios
7. Weakest Link - Dealing with The Weakest Link in a Sound Isolation Chain
8. Lab Testing and Results - Independent Third Party Transmission Loss Reports.