In many applications plates or impervious screen layers are perforated. That means there is a fraction of motion given by the flow through the
perforation of the plate. This is done by using the perforation keyword in the definition of the related infiniteLayers class.
Usually, a plate or mass layer is described by a transfer impedance 
. When the layer is in addition perforated and this perforation is described by the transferimpedance 
this can by implemented by assuming that both transfer impedances are working in parallel.
Z_{p,perf}=\left(\frac{1}{Z_p}+\frac{1}{Z_{perf}}\right)^{-1}=\frac{Z_p Z_{perf}}{Z_{p} + Z_{perf}}A limp mass layer with 
and a purely resistive perforation 
reads as:
Z_t =\frac{j\omega m' R_s}{j\omega m'+R_s}Details of implementation and examples can be found in the pyva documentation.
Installation update from the github page or with:
pip install pyva-toolbox