Creating a flat spectrum filterbank I'm trying to create a filterbank whose frequency response is generally flat when summed in parallel. Are there any tips to choosing center frequencies and bandwidths for a filterbank of overlapping bandpass filters? Does a gammatone filterbank sum up to a flat response?
There exist perfect reconstruction filter banks that do what you suggest.



One example of the choice of $H_i(z)$ for $i= 0 \ldots N-1$ is the FFT filters (followed by the IFFT filters $F_i(z)$).