The reason equalizer is created is to equalize speaker response throughout the human hearing frequency range 20Hz to 20KHz. As you know the speakers are not created the same.

However, human ears also are not flat in response either Listening to high volume sound too much, I became deaf to high frequency and need to compensate with equalizer

Here you can read and easily understand what you need to do to get more voice or what ever. Just play around and you will understand.

https://www.addictivetips.com/windows-tips/...yers-explained/