Marques A., Freitas D.

In a previous paper [1] the authors have proposed a novel approach for the equalization of non-minimum phase loudspeaker systems based on the design of IIR inverse filters. This approach allow inverse filter based equalization solutions with lower computational requirements and with lower delay of the equalized loudspeaker system than the most used one, the FIR filter, nevertheless with some more effort in the design process due to nonlinear nature of the problem. The advantage of the proposed method has been demonstrated with examples with off-line simulated data. In this paper further developments and new results are presented concerning the proposed equalization method. An experimental set-up has been developed for loudspeaker response measurement and equalization that uses as excitation signals Maximum Length Sequences (MLS). With this set-up, a 2–way loudspeaker system was equalized using the FIR inverse filters and the proposed IIR inverse filter. An objective comparison between the real results of these two solutions was done using as criterion the time domain and the frequency domain equalization errors and the delay of the equalized loudspeaker; the results of this comparison are presented and discussed. Also, listening tests results with the equalized loudspeaker system are outlined and discussed. [1] Marques, A, Freitas, D, Infinite Impulse Response (IIR) Inverse Filter Design for the Equalization of Non-minimum Phase Loudspeaker Systems, ICSV12, 2005