http://freedesktop.org/software/pulseaudio/doxygen/async.html#overv_sec

http://www.developpez.net/forums/d467150/autres-langages/algorithmes/fft-role/

http://code.google.com/p/jivemodular/source/browse/trunk/apps/jive/src/model/plugins/meters/AudioSpecMeterEditor.cpp?r=67
http://en.wikipedia.org/wiki/Frequency_weighting

http://en.wikipedia.org/wiki/Root_mean_square#RMS_in_frequency_domain