Thinking building your own studio lately?

While in VN the most interest bunch of folks I met were the Vietnamese architects. Most of these guys came out of school all had knowledges about sound and the reaction of building materials associated with their design works. I often get asked by them of the applications and how it may applied in the real world situations.
It is an interesting topics to get into for me, I also do want to learn a thing or two regarding architect designs and how it may help me in studio design situations.

Ok, I will start to submit things I found to be associate with sound and architect designs for studio or home studio in the future.

so far here is the start....

With most architect text I found in VN, all mentioned STC as way to determine material transmission value of building material...it is cool but wait, it's 2007 now, so let's clear this issues up.

The STC - or Sound Transmission Class - is a recognized standard and is, by far, the common sound isolation standard in use in North America today. Virtually every commentary that one reads focuses on STC, yet STC is not without significant limitations, and for a great many applications it is not a good measure of sound isolation at all. Before we talk about the limitations of STC as a rating, let’s take a look at what STC is.

What is STC?

Is STC a measure of how many decibels of sound a wall can stop? - No, it is not.

Is STC a ranking of how good a wall is? - No, for most applications it is not.

So what the heck is it? - It is a very old (1961) method for ranking walls over the frequency range of 125 - 4000 Hz, assuming that the noise the wall is trying to stop is generally even across the frequency spectrum.

The problems with the STC system

The three basic limitations of STC are apparent from the description of the system above.

1. It only considers frequencies down to 125 Hz.
The first, and most severe, problem with the STC system is that it only considers frequencies down to 125 Hz. What noise exists below 125 Hz?

• Most of the sonic energy generated by the average home theater
• A large percentage of the sonic energy generated by traffic, your neighbors in VN, and music
• Much of machinery noise

If you have sound isolation problems, there is a very good chance that it is low frequency noise you are having trouble with, so one could say that the STC calculation completely ignores the frequencies that are most problematic. That’s not good.

2. It assumes even energy dispersion. It is accurate within its frequency range only for noise sources that have approximately even energy levels across the frequency band. Most noise sources do not meet this criterion and some (like the average home theater) are worlds away from this criterion.

3. Its calculation system is archaic. STC dates back to 1961; a time before computers made complex calculations easy, and the method of determining STC reflects this. In today’s world more complex, vastly superior calculations can easily be done. OK, that’s great, but do any real problems actually occur?

So why is the STC system used at all?

Well, there are some very good reasons why the STC system is in use.

• It’s been around for so long that essentially every law, regulation, and piece of legislation relating to sound control is based on it. Old habits are hard to break.
• As frequency falls, the ability of the different labs to get consistent results also falters. +/- 3 STC points from lab to lab is typical, but if the STC system were extended down to, say, 40 Hz, this might increase to +/- 10 STC points or more, making the results basically meaningless.
• Its easier for companies marketing commercial products to attain a huge STC increase than it is to attain a huge increase across the full frequency range. This leads to a lot of focus on STC, and less discussion of critical things like low frequency performance.

Are there better rating systems?

Yes, the best standardized rating system in North America is called OITC, and is typically used for exterior wall elements. OITC features a modern calculation system and considers frequencies down to 80 Hz.

In Europe at times full-range standards are applied. An assessment of existing standards is given in the appendices of this document.

until next time....

Tran Duy