For more than two weeks I have been trying to understand how to implement an A-Weighted filter for psychology experiments.  Currently I have developed a program that will calculate an unweighted average of an audio file, with and without silence.  Silence is defined as a decibel value of 44db or less in a .05 second window.  Its been a very frustrating two weeks.  I've come across other sites that explain A-Weighting but I have not figured out how the digital filter is implemented.

http://www.beis.de/Elektronik/AudioMeasure/WeightingFilters.html#A-Weighting
http://www.ptpart.co.uk/show.php?contentid=70#FrequencyWeighting
http://en.wikipedia.org/wiki/A-weighting

Does anyone understand this and mind giving me direction on how to implement an A-Weighted filter. 

Thank you kindly,


W.