Parametric Equalization: The Easiest Way To Remove Unwanted Noise From Your Audio Tracks

People always seem to be fascinated with the ability of a sound engineer to take an audio track filled with hisses, hums, or pops and seamlessly isolate the sound they want, successfully eliminating all unwanted noised. While this isn't a skill that most amateur recording hobbyists tend to have mastered, I'm here to tell you that it's not as hard as it sounds...                                                                                                                                 

The key to eliminating unwanted noises from your mixes is a process known as "Parametric EQ Sweeping." 

Don't let the big words scare you, the actual process is much easier to perform than it is to pronounce! In order to explain what parametric EQ sweeping is, you must first learn what is meant by "parametric EQ." Parametric EQ is a type of equalizer plugin that displays the frequencies of sound in a graph-like format, as shown in the picture above. The low frequencies are on the left side of the x-axis, and the high frequencies are on the right. To put this in perspective, think of it like this:

Imagine the setting knobs on any particular guitar amplifier. Most guitar amps have individual knobs labeled "bass," "mid," and "treble." If you are familiar with how a guitar amp works, then you understand that when you turn up the bass knob, the sound of your guitar becomes, well, "bassier." The same thing applies to the mid and treble knobs on the amp as well, am I right?
Well, a parametric EQ plugin works the same exact way! Except, as you can probably see in the picture, a parametric equalizer gives you MANY more options as to which frequency you want to adjust. All you have to do is simply click and drag either upward or downward anywhere on the graph, and the corresponding frequency will be either boosted or cut, respectively.   

So now that you understand what parametric equalization is, let's learn how to use it to remove unwanted noises!

We will do these using a technique known as "Parametric EQ Sweeping," as I mentioned earlier. First thing's first, we have to go over what the different settings mean. Notice the box with the red arrow pointing to it in the picture above. In this box are the only settings that there are when it comes to using a parametric equalizer. Told you it's not as bad as it sounds! 

I'll start at the top, where you see the number "12.2" - 

This setting is as the "EQ Gain Level." What this does, is adjusts the decibel level at which you are boosting the chosen frequency. In other words, it's the value of the y-coordinate on the graph.

Next is the setting right under the gain level, which is simply the "EQ Band Frequency" - 

This adjusts the actual frequency that you're boosting. Lower numbers on this setting represent bass frequencies, and higher numbers represent treble frequencies. It can also be looked at the value of the x-coordinate - put two and two together and you'll find out that the highlighted point on the parametric EQ graph can be represented by the x, y coordinate (Frequency, Gain Level).

Lastly is the setting known as the "Quality Factory," which is normally referred to in the industry as the "Q Setting." In the picture above, it is the one that is currently set at 12.0 - 

The quality factor is the setting that adjusts the width of the area underneath the highlighted point in the eq graph. The larger the number, the skinnier the area is underneath the point. Twelve is the largest value that the Q setting can be adjusted to, and as you can see the area underneath the point is very skinny. Increasing the Q value with widen the area underneath your highlighted point, which in turn will slightly boost all of the other frequencies immediate surrounding the one you have selected. As you can see in the picture to the right, I've decreased the Q value to .5, which in turn made the area underneath the selected point much larger.

Now that you finally understand how to use a parametric equalizer, it will be very simple to explain parametric EQ sweeping to you!

1. First, set the gain level to a relatively high value, somewhere between 12-15 decibels. 
2. Next, set the Q value to 12, which is the highest it can go.
3. Your parametric EQ graph should look very similar to the original picture I used to explain the settings with.
4. Then, set the frequency band setting as low as it can go.
5. Now, play the audio track that you are trying to edit.
6. As the track plays, gradually increase the value of the frequency band setting. Notice how the skinny arch is "sweeping" across the graph.
7. As you do this, listen very closely for the spot where the unwanted noise is the loudest.
8. Once you have found that spot, leave the frequency band setting right on it and decrease the gain level to about negative 10-12 decibels.

Nice job, you just finished performing your first parametric EQ sweep! It does take lost of practice to be able to listen for the frequency spots where the unwanted noise is loudest, but over time you will develop this skill until you are just as good as any professional! If you have any questions about this process, or questions about parametric equalization in general, feel free to leave them in the comments section and I will get back to you!

As always, thanks for tuning in

- Trey