Comparison of digital loudspeaker - equalization techniques

An overview of digital equalization techniques for
loudspeaker systems is presented. The known algorithms are systematized and
modified. Equalization is effected by a single digital filter for the on-axis
loudspeaker response. Besides classical FIR and IIR digital filter structures,
their warped versions (WFIR and WIIR) are used to build equalization systems.
Equalizers of different types are compared with regard to efficiency. Also
information about objective and listening-test assessments of the quality of
equalization obtained by the different equalizers is provided. Besides the
equalizer quality assessment techniques know from the literature, new
techniques, which better represent the properties of the human auditory system,
are proposed. For the new techniques better agreement between the objective
results and the listening-test ratings was obtained. On the basis of objective
assessments of 32 equalization systems carried out for two stereophonic pairs of
loudspeaker systems algorithms yielding the best results for each of the tested
filter structures (FIR, IIR, WFIR and WIIR) were selected and evaluated by
listening tests. Key words: equalizer, digital filter, loudspeaker system.