Warped, Kautz, and Fixed-Pole Parallel Filters: A Review

In audio signal processing, the aim is the best possible sound quality for a given computational complexity. For this, taking into account the logarithmic frequency resolution of hearing is a good starting point. The present paper provides an overview on warped, Kautz, and fixed-pole parallel filters and demonstrates that they are all capable of achieving logarithmiclike frequency resolution, providing much more efficient filtering or equalization compared to straightforward finite impulse response (FIR) or infinite impulse response (IIR) filters. Besides presenting the historical development of the three methods, the paper discusses their relations and provides a comparison in terms of accuracy, computational requirements, and design complexity. The comparison includes loudspeaker–room response modeling and equalization examples.