SRI figures

marello · Post by **marello** » Thu Jan 05, 2006 11:18 pm

I'm desperately searching to find some SRI figures for simple construction materials such as plasterboard and mineral wool. I don't suppose anyone could be kind enough to link me to somewhere (if there is anywhere?). I've tried googling but I'm not having any luck!

AVare · Post by **AVare** » Fri Jan 06, 2006 12:43 am

What is an SRI figure? Something like an STC or OITC? The latter two are widely available. Bear in mind that STC is not suitable for studio isolation design due the lack of low frequency data in the calculation.

Andre

marello · Post by **marello** » Fri Jan 06, 2006 12:44 am

Sound Reductio Index, yes I think it is similar to STC, I've tried searching for that but had no luck either. I understand there's not much help with the low frequency when you're given an average number but this is for an estimate so it'd still be very useful.

AVare · Post by **AVare** » Fri Jan 06, 2006 1:01 am

STC? For a start here is a report with 351 wall constructions, their STC numbers and TL data down to 50 Hz. IR-761. It is sort a bible for gypsum construction walls. There are lots of additional test results available from the NRC. Use their search function. This link has many such reports linked in it.

A bit more detail would help us direct you in the direction of finding the inforamtion you are looking for. For example BBC RD1991-09 covers wood frames partitions evaluated by the BBC. The summary numbers are Rw (roughly european version of STC with some differences).

Andre

Post by **kendale** » Fri Jan 06, 2006 5:53 am

Aloha Marello,

Could you also:

Edit your profile to include your location. This is very important, because this is a worldwide resource, and as such, material costs and availability vary widely. For example, masonry is cheaper than gypsum in some parts of the globe, whereas it's the exact opposite in other regions.

Thanks!

(forum guidelines)

Perhaps this might be useful as well?

Aloha

knightfly · Post by **knightfly** » Fri Jan 06, 2006 6:35 am

Try searching for NRC figures; never heard of SRI... Steve

marello · Post by **marello** » Sat Jan 07, 2006 3:12 am

Profile changed, sorry!

SRI seems to be the UK term for STC I think? I definitely don't want NRC figures as I think they range from 0-1. As far as I know the SRI is the average figure that a material will reduce a sound by in dB when it passes through. I know it's not accurate when you average over the frequency band but it just helps to give me a rough idea.

I'll confess this is for a final year University project (designing a recording studio with relevent calculations). My lecturer wants an estimate of the SRI (STC) of our structures, unfortunately none of our books seem to list these figures and google isn't particularly helpful.

I'm looking for figures for:
Mineral wool (various densities)
Deadsheets (3.5kg/m2 and 5kg/m2)
Cotton Waste Fibre

I've managed to find structural type ones now, thanks for the links

Unfortunately most of them seem to be broken, but any help is appreciated!

bert Stoltenborg · Post by **bert Stoltenborg** » Sat Jan 07, 2006 9:36 pm

In a recording studio you deal with music. Music has a spectral composition making transmission loss calculations according to STC a joke.
You have to use a weighting like the dutch Tennekes to get usefull results, if you want one number values. You can also just calculate TL in 1/3 or 1 octave bands and look at them to get an idea.
Your lecturer should know that.

Never heard of SRI.

marello · Post by **marello** » Sat Jan 07, 2006 9:54 pm

Thanks Bert for the reply. Naturally I was hoping to find figures per octave band. However this is for an estimate of the efficiency of our constructions. From the few figures I've found so far I understand that the materials are not as effective at lower frequencies, however looking at minimum audible field graphs it also shows that you can afford to have a higher level of bass being transmitted through the structure.

SRI when it is given as Rw is a weighted measurement from what I can gather.

Jedanor · Post by **Jedanor** » Mon Jan 09, 2006 1:55 am

bert Stoltenborg wrote:In a recording studio you deal with music. Music has a spectral composition making transmission loss calculations according to STC a joke.
You have to use a weighting like the dutch Tennekes to get usefull results, if you want one number values. You can also just calculate TL in 1/3 or 1 octave bands and look at them to get an idea.
Your lecturer should know that.

Never heard of SRI.

There used to be an MTC rating for Music Transmission Class that was available to rate a partition below 125 Hz. I believe the origins were from ASTM (same as E-90 for STC) but I'd have to do a little research to confirm. I have a disk somewhere filled with various tests by Riverbank, Twin Cities and USG where partitions are rated for both MTC and STC. I think NRC also had some of their data in there.

AVare · Post by **AVare** » Mon Jan 09, 2006 4:57 am

marello wrote:. Naturally I was hoping to find figures per octave band.

SRI when it is given as Rw is a weighted measurement from what I can gather.

Now you are starting to communicate effectively! All modern test data on TL that I am aware of based on 1/3 octave tests. Reporting may for every third band, but it is still 1/3 octave data.

The two links I gave you initialy have the actual TL data and the BBC has Rw, exactly what you asking for. The BBC has many reports on TL for various partition systems, as does the NRC.

Have fun!
Andre