To provide a filter apparatus and a method for filtering a time domain input signal, and a filter generator and a method for generating an intermediate filter definition signal.

The filter apparatus comprises a complex analysis filter bank for generating a plurality of complex subband signals from the time domain input signals, and a plurality of intermediate filters. At least one of the plurality of the intermediate filters has non-uniform amplitude/frequency characteristics, and the plurality of intermediate filters have a shorter impulse response compared to an impulse response of a filter having filter characteristics. Thus, the non-uniform amplitude/frequency characteristics of the plurality of intermediate filters attain the non-uniform filter characteristics, and a complex synthesis filter bank for synthesizing the output of the intermediate filters to obtain the time domain output signal.