Design of digital parametric equalizer based on second-order function

Equalizer consists of multiple peaking filters or cutting filters. A good sound quality will be produced through independently varying the bandwidth, center frequency and gain of each filter of equalizers. The design of parametric equalizer has its peculiarity because of its particular amplitude to frequency feature and its parameters adjustment way. In this paper, we firstly define three user parameters which are related to audio effect, and then the user parameters are translated into the digital filter´s coefficient according to mathematical criteria. Therefore the coefficients in our digital parametric equalizer are not only directly related to the audio effect, but also make those center frequency points independent after their series. The quality factor Q of filters doesn´t vary with frequency, and thus they have high practical value. A practical structure without circular buffer is presented finally.