John Sayers' Recording Studio Design Forum Archive

I work at Lowes, and all of our bathroom/Lavatory fans have a sound/loudness rating that's measured in Sones. 0 is the quietest and they go up to 7 or 8. Is there any sort of similar rating for HVAC systems?

Have you seen this?

Quite an interesting site overall actually.

One of the better explanations I've seen -

http://www.phys.unsw.edu.au/~jw/dB.html

In particular, check out the equal loudness curve chart, followed by the sone/phon comparison... Steve

I'm an HVAC half-wit, so can't say how they even rate systems; but this should let you convert whatever is stated...

If you want to find your OWN PERSONAL equal loudness curves,

http://www.phys.unsw.edu.au/~jw/hearing.html

Hi Steve,

Just some info:
The curves on that Univ link you gave are wrongly identified:
Curves of equal loudness determined experimentally by Fletcher, H. and Munson, W.A. (1933) J.Acoust.Soc.Am. 6:59.

This are NOT the Fletcher and Munson curves.
The original Munson Curves yoiu can find here:
http://www.mcs.csuhayward.edu/~tebo/Cla ... ption.html


Source: http://www.mcs.csuhayward.edu/~tebo/Cla ... Munson.gif

What you're looking at on that page you linked:
http://www.phys.unsw.edu.au/~jw/dB.html
are the equal loudness curves derived from the original
D.W. Robinson and R.S. Dadson curves:
A re-determination of the equal-loudness relations for pure tones.
British Journal Applied Physics 1956 v7 pp. 166-181.

I find it rather questionable that a University makes such kind of error, meaning they didn't bother to check the original papers. More: I found a name, I found a graph, lets combine them, who knows .....

The latter were integrated in ISO 226: 1987 and are the ones you find in lots of books and papers related to equal loudness curves.

Problem:
While the Dadson curves were designed as improvement of the original Fletcher curves, the Dadson curves proved to deviate significantly from studies done in the last 10 to 15 years.

This resulted in NEW equal loudness curves integrated in ISO 226: 2003.
The differences are significant (up to ca 14 dB).
Those curves you will find nowhere on the net yet (or in books yet for that matter).

The dB(A) correction was based on the 40 line of the ORIGINAL 1933 Fletcher curves and in fact existed already before the first loudness curves were integrated in ISO.

I expect the ASTM world to take over those recent end 2003 curves, which are based on much more extensive studies (including many countries + all earlier studies) than the former ones.

This is yet another of those net copy things.
You can't believe what a mix you find on the net; Fletcher curves are called ISO or Dadson loudness curves and mainly vice versa Iso curves get the name of Fletcher even with exact described (BUT COMPLETE WRONGLY USED) reference to an article in JASA.

Eric, as usual every time you post I learn something; thank you.

Question: Since the newer equal loudness curves aren't available yet, which (if any) of the OLD curves are closer to the newer findings?

Again, thanks for the clarification... Steve

Hello Steve,

I'll check.
I was busy programming them all 3, but got stuck (time).
When I have a better overview I'll come back on this.

Just VERY superficially.

The new ones look superficially more as the Dadson curves, but when compared in numbers (not looks) it's possible the Fletcher ones will be closer.

So give me some time.

Due to the extreme strict Copyright issues on those recent standards, I can't put them on the net.
(that relates to the quality versus quantity copyright rules - those curves are the hart of the standard).
When ordering an ISO standard on ANY individual page a strict Copyright notice is integrated with one's personal name and co-ordinates, prohibiting copying and networking.

When ordering an ISO standard on ANY individual page a strict Copyright notice is integrated with one's personal name and co-ordinates, prohibiting copying and networking.

When the check clears the bank Eric, what do you have? Can you write it in your own words? And who writes the standard? Do they work for companys that USE the standard? Thanks for any info. Just trying to learn. Hell, 6 months ago I thought standards were available freely to consumers so when you read your PRODUCT manual, you would KNOW what they mean. Otherwise, why would they write "this product built to such and such standard", which now I see means NOTHING to the consumer, cause he can't read the damn thing. Kinda like "coefficients". Show me a consumer that would even know how or why coefficients are even used.
fitZ

PS. The next time I see an ISO or ASTM standard listed in a product, I think I
m going to tell them........PROVE IT