What does EQ (equalization) change in audio?

EQ (equalization) changes the frequency content, or the tonal balance, of audio. It allows you to adjust the relative levels of different frequencies in a sound, boosting or cutting specific frequency ranges to shape its sonic character. EQ is used to correct tonal imbalances, enhance desirable frequencies, and reduce unwanted frequencies, such as noise or muddiness. It works by applying filters that attenuate or amplify specific frequency bands. For example, you might use EQ to boost the high frequencies of a vocal track to add clarity and presence, or to cut the low frequencies of a guitar track to reduce muddiness. EQ is typically implemented using a graphic equalizer, which provides sliders for adjusting multiple frequency bands simultaneously, or a parametric equalizer, which allows for more precise control over the frequency, bandwidth (the range of frequencies affected), and gain (the amount of boost or cut) of each band. By selectively adjusting the frequency content of audio, EQ can dramatically alter its sound, making it brighter, warmer, clearer, or more impactful.