Low pass filtering in WFS rendering

[KChablas]

Hello,
I am using the sfs toolbox to render some audio files to be played in a real WFS array of 16 loudspeakers in a project for my diploma thesis. When we played back the audio fileswe noticed that they sounded like a low pass filter had been applied to the signals. At first we thought that maybe this happened due to colouration or aliasing. So we used signals with low frequency contentinn order to avoid any frequency above the aliasing frequency. However the issue persisted.

I use the sfs.td.wfs.point_25d to place the point source and then the sfs.td.wfs.driving_signals to get the driving signals and save them in a wav file

The weird thing is that when I placed the point source far away from the array this problem did not exist or it was not so noiticeable. It is when I put a source close to the array that this happens