EQUALIZATION FILTER

An equalization (EQ) filter is a filter, usually adjustable, designed to compensate for the unequal frequency response of some other signal processing circuit or system. In audio engineering, the EQ filter is more often used creatively to alter the frequency response characteristics of a musical source or a sound mix.

An EQ filter typically allows the user to adjust one or more parameters that determine the overall shape of the filter's transfer function. It is generally used to improve the fidelity of sound, to emphasize certain instruments, to remove undesired noises, or to create completely new and different timbres.

Equalizers may be designed with peaking filters, shelving filters, bandpass filters, or high-pass and low-pass filters. Dynamic range circuitry can be linked with an EQ filter to make timbre changes only after a signal passes an amplitude threshold, or to dynamically increase or reduce amplitude based on the level of a frequency band. Such circuitry is involved in de-essing and in pop-filtering.[1]

 

References:

[1]. http://en.wikipedia.org/wiki/Equalization_filter