Parametric Equalizer
Type of equalizer that allows the user to adjust a signal's frequency response
with complete choice over how to break up the signal and adjust it using
amplitude, center frequency and bandwidth.
Equalizers adjust frequency response by changing the amplitude of a signal at
a certain point thus changing the loudness of the signal at that point. This
can be used to boost a signal that sags or loses output over a certain frequency
band or bring down a signal that is too powerful over a certain frequency band
with the end result being a flat (or flatter) frequency response (a flat
frequency response being a desirable trait meaning the audio system is not
attenuating or boosting the signal where it should not). When a signal is
equalized, its amplitude is changed at some center frequency and over some
range or band of frequencies on either side of the center.
In a graphic equalizer the center frequencies and associated bands are fixed
with only the amplitude adjustable. A parametric equalizer allows the user to
select the center frequency and bandwidth to be affected by an amplitude
adjustment. In this way, the parametric equalizer offers the maximum amount of
flexibility and customizability versus a graphic equalizer. Generally, a graphic
equalizer is adjustable at a large number of frequencies (as many as 30 center
frequencies) to allow fairly precise control over the frequency response while
a parametric equalizer only adjusts a few areas of the frequency, which are
carefully chosen.