Open your preferred digital audio workstation, for example Pro Tools or GarageBand. Depending on how your program is configured, either the last-saved session or a blank session automatically opens. To call up a work-in-progress, open the file menu and select the session from the drop-down menu underneath the "Recent," or "Open Recent" options, depending on the program.
Select a sound or instrument to equalize. You typically apply post-production equalization to a single audio channel, to enhance or tweak the sound of the recording on that channel. Mix eq applies to an entire mix, but comes after individual tracks are balanced and equalized. It's a matter of preference, but it is typical to begin by equalizing the lowest frequency sounds first, such as drums. This sets a foundation and reference for the remaining sounds.
Click on the selected audio channel. This assigns subsequent commands to that channel specifically, rather than to the entire mix.
Open the equalizer. The specific command varies according to which program you are using, but you typically open it from the "Effects" menu. For example, in Logic, click "Effects, "Eq" and then select an equalizer tool from the menu. This opens a separate window, featuring an array of slider dials and a grid with a super-imposed curve. The dials control the level of individual frequencies. The "Gain" dial controls the level of the highlighted frequency.
Press "Play" so you can hear your frequency adjustments in real-time.
Click on the frequency curve. The curve sits on a grid. The horizontal axis represents frequency and the vertical axis represents amplitude. The frequency make-up for the sound determines the shape of the curve. Move the curve around the grid to alter the frequency. This is the standard technique for identifying rogue frequencies. For example, if there is an unwanted hiss on a recording, you'd manipulate the frequency curve on screen until that hiss became the loudest feature of the playback.
Release the mouse to highlight the frequency. Adjust the gain to determine the level of the highlighted frequency relative to the remaining frequencies. If it's a good sound, increase the gain to enhance it. If it's an unwanted sound, drag the gain to zero. Repeat this process for each channel to be equalized.
Click "Save" and quit the equalizer.