Frequency warping in the design and implementation of fixed-point audio equalizers

This paper discusses the use of frequency warping for designing and implementing a class of discrete-time filters. This technique is particularly useful for audio filters because specifications are often given on a logarithmic frequency scale. It is shown that frequency warping allows a class of recursive filters to be designed using standard FIR techniques, and naturally leads to a structure for implementing the filters. The fixed-point behavior of this filter structure is analyzed and is shown to be relatively insensitive to coefficient quantization and round-off noise.