Choose a frequency band to adjust on your parametric equalizer, such as the high frequency band, which is often labeled "HF." Each parametric equalizer is made differently. Some have 10 or more frequency bands you can adjust, while others have as few as 3. Regardless of how many bands your parametric equalizer has, each frequency band will have "Frequency," "Bandwidth" and "Gain" controls.
Choose the "Notch" or "Shelf" button within this frequency band (some parametric equalizers will have fixed "Notch" or "Shelf" settings). Selecting the "Notch" button will allow you to cut or boost a set range of frequencies, making a "Notch" in the parametric equalizer. Selecting the "Shelf" button will allow you to cut or boost all frequencies above or below the frequency range you select, making a "Shelf" in the parametric equalizer.
Adjust the "Frequency" control, often labeled "Hz," to select the desired frequency range you would like to cut or boost.
Set the "Bandwidth" control, also called the "Q," to adjust how wide or narrow the equalizer band is. For example, a bandwidth of 1 will be much wider than a bandwidth of 10. If you wish to make subtle equalization adjustments, choose a wide bandwidth. If you wish to make more precise equalization adjustments, choose a narrow bandwidth.
Adjust the "Gain" to cut or boost the frequency range you have selected. To de-emphasize the frequency range you have selected, reduce the gain (this is called subtractive equalization). To emphasize the frequency range you have selected, increase the gain (this is called additive equalization).