Logarithmic Frequency Scale Parallel Filter Design With Complex and Magnitude-Only Specifications

Recently, the fixed-pole design of second-order parallel filters has been introduced to accomplish arbitrary (e.g., logarithmic) frequency resolution for transfer function modeling and equalization. The frequency resolution is set by the pole frequencies, and the resulting filter response corresponds to the smoothed (moving-average filtered) version of the target frequency response. This letter presents the frequency-domain version of the design algorithm for complex and real filter coefficients. The proposed frequency-domain design, besides its computational benefits, allows the use of frequency weighting. In addition, a magnitude-only variation of the algorithm is proposed. Examples of loudspeaker-room modeling and equalization are presented.