The basic idea is to partition FFT bins into the desired nonuniform bands, and perform smaller inverse FFTs on each subband to synthesize downsampled time-domain signals in each band. A simple example for a length 8 FFT octave filter bank is shown in Fig.10.30. We'll next extend this example to a practically useful level via a series of tutorially oriented matlab examples.
Summing STFT Bins
Audio Filter Banks