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

The filter apparatus for filtering a time domain input signal filtered using a filter characteristic having an non-uniform amplitude/frequency characteristic so as to obtain a time domain output signal comprises a complex analysis filter bank 101 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 the non-uniform amplitude/frequency characteristics, and the plurality of intermediate filters have a shorter impulse response compared with an impulse response of a filter having the filter characteristics. The non-uniform amplitude/frequency characteristics of the plurality of intermediate filters represent the non-uniform filter characteristics, and a complex synthesis filter bank 103 for synthesizing the output of the intermediate filters so as to obtain the time domain output signal.