Cut off the frequencies below 60 Hz to get rid of unnecessary bass frequencies picked up by the vocal microphone. Cutting the frequencies below 60 Hz will rarely affect the tone of the vocal, but can get rid of low-end rumble transmitted through the microphone stand and picked up by the microphone.
Decrease the volume of frequencies anywhere from 60 Hz to 200 Hz to thin out a vocal that is too heavy and thick sounding. This will help add clarity to a vocal with too much bass.
Increase the volume of the frequencies around 150 Hz to add thickness to a thin sounding vocal.
Increase the volume of the frequencies around 3 KHz to add extra clarity and intelligibility to a vocal.
Increase the volume of the frequencies around 5 KHz to add extra presence to a vocal, which will allow it to cut through the mix.
Decrease the volume of the frequencies around 7 KHz if the vocal is too sibilant, or has too much emphasis on the “ess” sounds.
Increase the volume of the frequencies from 10 to 15 KHz and above to give the vocals a bright and airy sound.