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In the Forum: Audio Discussions
In the Thread: Measuring reality: empirical mode decomposition
Post Subject: Measuring reality: empirical mode decompositionPosted by decoud on: 3/2/2008
It seems there is broad agreement here with what I take to be Romy's position, which is that one cannot have a sophisticated understanding of music reproduction if one does not have a sophisticated knowledge of music. Indeed, it ought to be obvious that for the person whose only exposure to live music is pop concerts - where everything is crudely amplified - "realism" will be only a matter of loudness. But knowledge of live music is not sufficient: one also needs to have a deep understanding of the possibilities of reproduction, which - as this site illustrates - is hard to achieve without long and arduous exploration.
Now all of this would be easier if one had some better measures by which the fidelity of reproduction could be gauged - not as a substitute for listening but as an adjunct. The various functions of frequency commonly quoted are not very useful because they assume that the sound is stationary, which of course it is not. The only non-stationary test one tends to see - the response to a step function - is of course a very artifical thing.
So, what we need is a method for analysing non-stationary, non-linear, time-varying signals. The best of these is probably empirical mode decomposition. Romy, would you be persuaded to give it a try? (there is a version for MATLAB here http://perso.ens-lyon.fr/patrick.flandrin/emd.html) I do not for a minute believe it would be as good as a human ear, but it may be interesting to show that it can capture aspects of "reality" missed by crude things such as bandwidth and distortion values.Rerurn to Romy the Cat's Site