Maya formula for a sound spectrum

Basically recreate the sound specturm formula in this paper: http://www.cs.columbia.edu/cg/lego/acoustic-voxels-siggraph-2016-li-et-al.pdf

I have already designed a sample filter (.obj) which can be imported into Maya. I want to know what the sound spectrum looks like after i feed some sound (a physical tap at the open end) into the filter. The formula needs to be inputted into Maya. I want this formula that works in Maya and can be used for any more filters that i create. An explanation of how the formula works is needed too.