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.
mfga.sdr IOhannes
Thanks !