To equalize is to obtain a desired overall frequency response through the use of a graphic equalizer.

Frequency is the number of vibrations or oscillations in units per second, which is measured in cycles or Hertz per seconds. It is said that the human ear can perceive a range of sound frequencies from 20 Hertz (twenty cycles per second) to 20 kiloHertz (twenty thousand cycles per second), but of course, that does not apply to all of us. Audio equalizers allow you to adjust levels at points in a range of frequencies.

Each point is called a band and the more bands available for adjustment within a frequency range, the more precise the audible adjustments become. Many digital audio playing programs include an equalizer with anything from two (2) bands; as treble and bass sliders, up to over 100 bands each adjusting a certain frequency and surrounding frequencies. The gain of a frequency can be boosted (an increase in gain of a frequency or band of frequencies) or cut (reduction in gain or attenuation of a frequency or band of frequencies) by decibels (dB), increasing or decreasing the volume, noise or intensity of that frequency.

In this way it is possible to target certain frequencies in a range to improve (or distort) the sound. Bass boost buttons or dials on hi-fi systems increase or 'boost' in decibels the frequencies at the low end of the audible range, while treble adjustments increase in decibels the frequencies at the high end. Bass, treble and mid-range frequency adjustments differ depending on the type of music you are listening to. To create the best sound for techno and dance tunes, higher bass and treble frequencies are advisable, but the same frequency settings would not usually suit listening to classical or metal. This is because different musical instruments (including the human voice) create frequencies located in specific areas within the audible range.

Winamp equalizer presets for;

TECHNO:	POP:	CLASSICAL: