[PD] isosonic curves : level the perceptual loudness of different pitches

Alexandre Porres porres at gmail.com
Wed Mar 24 23:16:13 CET 2010

Hi, I found an acient thread that really interests me a lot!

In Fact, I just compiled 2 ways of doing the phons curves, by
Robinson-Dadson, and the ISO226:2003.

I will look now for this iem_matrix object and see what it does. In
the meantime, I'm wondering what else more related to the subject
there is.

For example, I know now that in Super Colider you can analyze a sound
via FFT and it will give you the loudness in sones.

I think I believe I saw something about a MAX object named [loudness]
on the net, and I assume it might do something similar.

Do we have something for that in Pd?



ps. Oh yeah, I attached my stuff, the objects are inside my roughness library.

Alexandre Quessy wrote:
>* Hi all,*>* *>* I would like to create an abstraction to adjust the amplitude of*>* synthetic sounds according to the ear sensitivity. At a given*>* amplitude, we hear the notes in the middle range louder than the high*>* and low notes. This perceptual property of the audition can be*>* somewhat undesired in a musical work. (in my opinion at least)*>* *>* The equal lines of actual amplitude of notes that seem to have the*>* same loudness are called "isosonic curves". Here are 2 different*>* graphics of these curves :*>* *>* http://www.multimedia.uqam.ca/cours/audio/images/diag/sonpsy_isoson.gif*>* http://www.comm.uqam.ca/GRAM/illu/mus/nature/CourbeDIsosonie.GIF*>* *>* A few links that might give you a few hint for the calculations :*>* *>* http://en.wikipedia.org/wiki/DB%28A%29*>* http://en.wikipedia.org/wiki/Weighting_filter*>* http://en.wikipedia.org/wiki/Stevens%27_power_law*>* *>* Anyone would have a formula or a table containing data that could help*>* me to calculate this ? For instance, we would be able to generate sine*>* waves of any frequencies that would be perceived as having the same*>* intensity for all of them, by changing their amplitude according to*>* this leveling formula . This way, we could hear our low freq notes as*>* much as the middle ones. Very valuable. :)*
btw, there is an object in iemmatrix called [mtx_phon_curve] which
should give you what you want.

since it is an abstraction, you can even see how the curves are created.


>* *>* Thanks !*
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