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Highlights from
ISO 226 Equal-Loudness-Level Contour Signal

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ISO 226 Equal-Loudness-Level Contour Signal

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01 Mar 2005 (Updated )

Generates a psychoacoustic equal loudness contour (curve) as described in ISO 226.

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Description

This function will return a 29-point equal loudness contour for your desired phon level. The frequencies evaulated in this function only span from 20Hz - 12.5kHz, and only 29 selective
frequencies are covered. This is the limitation of the ISO standard.

In addition the valid phon range should be 0 - 90 dB SPL. Values outside this range do not have experimental values and their contours should be treated as inaccurate.(Limitation due to standard)

If more samples are required you should be able to easily interpolate these values using spline().

*For more information regarding this method refer to ISO 226.

------------------------------------------------------------
Usage: [SPL FREQ] = ISO226(PHON);
 
        PHON is the phon value in dB SPL that you want the equal
          loudness curve to represent. (1phon = 1dB @ 1kHz)
        SPL is the Sound Pressure Level amplitude returned for
          each of the 29 frequencies evaluated by ISO226.
        FREQ is the returned vector of frequencies that ISO226
          evaluates to generate the contour.
------------------------------------------------------------

MATLAB release MATLAB 7.0.1 (R14SP1)
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Comments and Ratings (29)
07 Mar 2013 VPG  
01 Jan 2013 Jeff Tackett

Hi Olivier, in order to understand the symbols you must purchase the publication of ISO226. This MATLAB function only implements the mathematics described there. But to summarize, dozens of loudness tests have been performed over the last ~80 years and this function fits a curve to all of these tables. If you read the paper many of your questions will be answered.

28 Nov 2012 Olivier Baudry

It's not precised in this script what is it ?about af, Lu, Tf, and Ln, , what are the symbol represented by af, Lu, Tf, and Ln? Where the vales come from (arbitrary or not) Tf af, Lu, Tf, and Ln : what is it ?

07 Nov 2012 Radek

I've upgraded a bit your function, now it accepts expressions like surf(iso226(20:10:80)) https://www.box.com/s/g1cdj6q30ho5w3gvt80j producing beautiful 2D map

21 Dec 2011 harsh

can anybody here tell me wat information we get from equal loudness curve?plz tell me. my Btech project is related to this?
i am also lookin to generate Masking Curves

21 Dec 2011 harsh  
21 Dec 2011 harsh  
21 Dec 2011 harsh  
21 Dec 2011 harsh  
21 Dec 2011 harsh

can anybody here tell me wat information we get from equal loudness curve?plz tell me. my Btech project is related to this?
i am also lookin to generate Masking Curves

05 Aug 2011 Alex  
15 Mar 2011 oddo

here is a free excel file for loudness calculation:
www.noisestructure.com/products/Loudness.php

18 Oct 2010 Alex Nieva  
04 Aug 2010 Francois-Xavier Brajot

So helpful. thx!

17 Apr 2010 Prawinath Aponso

Hey guys, I tried running this script but it returns with an error message at line60. Could any of you guys give me some feedback on the problem.

For example i tried iso226 [52 63], and it returned that error message

Thanks

16 Oct 2009 Germ  
01 Oct 2009 Pradeep

It is not clear whether it is ISO 226 : 2003 or 1987 standard ?

15 Aug 2008 Abbas Khudair Abbas

good job Jeff

04 Dec 2007 Vincenzo Gambino  
18 Oct 2007 bo qin

a thousand thanks!

02 Oct 2007 enrico cignoni  
11 Jul 2007 Pablo Henriquez

Great and usefull application. Thanks Jeff

12 Jan 2007 Julien Riquelme

Very usefull to improve my audio mastering to improve the loudness of the CD... Thanks a lot !

27 Apr 2006 Laurent SIMON

Very useful to me too... I lacked of something like this...

18 Feb 2006 MarC .

Thank you. It was really useful for me.

26 Jan 2006 Johannes Buechler

Neat implementation of the formula from ISO standart 226. Thanks a lot!

23 Jan 2006 William Hooper

I agree with the earlier comments, that this is a welcome addition to the acoustic data information available on the internet.

28 Dec 2005 . .

This code contains the only fee-free "nearly closed form" expression for the ISO curves I've been able to find online. Nice.

06 Mar 2005 Christian Schultes

No running without the Communication Toolbox

Updates
04 Mar 2005

Added Screenshot image.

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