I'm trying to implement "accurate" C-weighting filter for range 20Hz-20kHz by using other than bi-linear transformation method.
What I've achieved so far is 10th order filter by using Magnitude Invariance Method (MIM):
but, as the method has an issue with HPF --> this is the lowest order implementation I can accept the result of.
I know it does not need to be that high order filter to get accurate response but, so far I have not found a solution to mix HPF (BLT) filter and matched LPF (non-BLT).
Is it possible to combine a BLT type filter with non-BLT filter (using Matlab/Octave) or, is it the only way to go by trying to improve BLT type filter response ?