An apparatus, and related method, relates generally to viable bandwidth filtering. In such an apparatus, an analysis filter bank has path filters associated with different bandwidths and is configured for filtering and transforming an input signal having a first bandwidth into a first interleaved output. A mask is coupled to the analysis filter bank and configured for masking at least one narrowband time signal of the first interleaved output. A synthesis filter bank is coupled to the mask. The synthesis filter bank is configured for transforming and filtering the masked first interleaved output to generate a second interleaved output for constructing an output signal having a second bandwidth. The second bandwidth is different than the first bandwidth for the variable bandwidth filtering.