Voices, environments, microphones, all create bad frequencies.
Certain ranges that sound bad or grating to the ear.
This can be very fatiguing to listen to, especially for long periods of time. You might not even realize it until after you're done listening to it.
This is where the "notch filter" comes into play.
There's several ways to perform this task, but basically it's the practice of removing a small band of frequencies within your audio.
It's important to remember not to go overboard with this, it can quickly cause more harm than good!
For more information about notching frequencies, message me anytime for a consultation!