ISO 226 Equal-Loudness-Level Contour Signal

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

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.

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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.
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• MATLAB release: MATLAB 7.0.1 (R14SP1)

[Christian Schultes]

No running without the Communication Toolbox

[. .]

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

[William Hooper]

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

[Johannes Buechler]

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

[MarC .]

Thank you. It was really useful for me.

[Laurent SIMON]

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

[Julien Riquelme]

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

[Pablo Henriquez]

Great and usefull application. Thanks Jeff

[enrico cignoni]

 

[bo qin]

a thousand thanks!

[Vincenzo Gambino]

 

[Abbas Khudair Abbas]

good job Jeff

[Pradeep]

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

[Germ]