STC Principals Explained

The Truth About STC
The best place to start is with a discussion of the ever-present STC system. If you've done some looking into sound isolation, you have probably seen STC ratings for different walls. If you click the Understanding STC link, you will get some discussion of STC - what it is, and more importantly, what it isn't. STC has one huge problem - it completely ignores low frequency performance. As a result, for most applications, STC is not a good indicator of performance, and you shouldn't rely on it. Understanding STC. But before you get started reading about STC, make sure to check out this short page about “Transmission Loss”, and how to read the graphs you see.
The Basic Principals Involved in Sound Isolation / Soundproofing
Rather than looking blindly at STC ratings, this section of our site will look at overall wall performance. And, what better place to start than with some discussion of the Five Basic Principals of Soundproofing / Sound Isolation - the 5 things that can help your walls stop more sound. From there we'll look at the Four Basic Ways to Improve the Performance of a Wall.
Resonance and the Low Frequency Performance of Walls
Often low frequency performance of walls is lost in the shuffle of discussions revolving around STC. We take the most thorough look at the low frequency performance of most common wall types in a careful and systematic way. We believe that the data contained herein is the fruit of the single largest full-range (31.5hz) study on walls to date.Read: Effect of Insulation in the Common Walls
New Construction
If you want to just cut to the chase, and see how different walls perform, or if you want to see those Principals in action, check out this page, which steps you through the performances of different walls that you can opt for in new construction, complete with lab data.
Remodeling and Upgrading an Existing Room
If you have a situation where you want to soundproof an existing wall or ceiling, we will take you through the options available to you in upgrading what already exists, complete (again) with lab data. Working with what you have can save a lot of money that would otherwise be spent tearing down, and replacing, what you already haveRead: Updating Existing Walls SoundproofingRead: Upgrading Existing Floors Soundproofing
No Partition is Better than its Weakest Link
For some situations, the choice of main wall (or floor/ceiling) construction + consideration of flanking noise is enough. However, for partitions that are to include windows or doors, the performance of those items must also be considered. We'll take a look at the impact of these kind of things on overall performance, and step you through how to get the most bang for your buck (or to reach the absolute performance you desire).Read: Tend to the Weakest Link in your Soundproofing Chain
Flanking Noise
While choosing a wall is very important, it’s only part of the process. You also have to deal with noise that, for example, reaches an upstairs room via a path other than the floor/ceiling. Examples of such noise paths would be into the walls and up the structure, through ductwork, etc. Our flanking noise page will let you plan for all of these potential problems.Read: Understanding Flanking Noise
Impact Noise/Footstep Noise
Those ever-annoying upstairs neighbors. Here we take a look at the basic possibilities that exist with respect to taming impact noise.Read: Understanding Impact Noise
That Should Cover it!
We’ve covered the Principals that affect isolation, how they interact in real walls, how to choose a construction to meet your needs, upgrading existing walls, dealing with flanking noise, and how to deal with typical “weak links” like doors and windows. And we’ve taken a one-of-a-kind look at the low frequency performance of walls in a way that has never been done before.
Good luck, and don’t hesitate to write with feedback or specific applications.

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