A Parametric Equalizer with Interactive Poles and Zeros Control for Digital Signal Processing Education
This article presents ZePolA, a digital audio equalizer designed
as an educational resource for understanding digital filter design.
Unlike conventional equalization plug-ins, which define the frequency response first and then derive the filter coefficients, this
software adopts an inverse approach: users directly manipulate the
placement of poles and zeros on the complex plane, with the corresponding frequency response visualized in real time. This methodology provides an intuitive link between theoretical filter concepts
and their practical application. The plug-in features three main
panels: a filter parameter panel, a frequency response panel, and a
filter design panel. It allows users to configure a cascade of firstor second-order filter elements, each parameterized by the location of its poles or zeros. The GUI supports interaction through
drag-and-drop gestures, enabling immediate visual and auditory
feedback. This hands-on approach is intended to enhance learning
by bridging the gap between theoretical knowledge and practical
application. To assess the educational value and usability of the
plug-in, a preliminary evaluation was conducted with focus groups
of students and lecturers. Future developments will include support for additional filter types and increased architectural flexibility. Moreover, a systematic validation study involving students
and educators is proposed to quantitatively evaluate the plug-in’s
impact on learning outcomes. This work contributes to the field
of digital signal processing education by offering an innovative
tool that merges the hands-on approach of music production with
a deeper theoretical understanding of digital filters, fostering an
interactive and engaging educational experience.