When you are working on improving the audio quality of your podcast, you will most likely want to use a Noise Gate to improve the sound of your podcast. But what exactly is this odd-sounding filter, and how does it work? In this article, we will cover what a noise gate is and how to use it.
Noise in General
As a podcaster, you want your audience to be immersed in your content without being distracted by background noise or unwanted sound artifacts. You will inevitably have some type of noise that you want to filter out during your recording session. Probably the most obvious one that people often overlook, is noise bleeding in from the person across from you when they talk! Well the good news, is that you can almost completely remove that low-volume noise in the background and other things like air conditioners, and so on, with a noise gate filter.
How A Noise Gate Filter Works
In essence, a noise gate filter will help remove sounds at or below a certain threshold that you set. You can adjust various settings such as the attack, hold, and so on. If when your speaker is silent on the track you are filtering, the noise level is -48db for example, you will set your noise gate around -45db. The effect that this has is in essence muting the track, unless the volume suddenly pierces this threshold. And that would usually only occur if you suddenly spoke into the microphone.
By using the noise gate filter in this fashion, you will remove all background sounds when the speaker is not speaking into the microphone. This will help to control the bleed of the other voice in the room.
How to Correctly Setup a Noise Gate
Now that you understand what a noise gate does, let’s look at some caveats that you must be aware of so that the noise gate works exactly as you intend it to.
In the world of audio mixing and mastering, there is a general sequence you should follow in applying your audio effects and filters. There are, of course, personal preferences and not everyone will follow this exact same sequence, but it is a very good guide that will ensure the best possible quality of your audio mix.
Try to apply your audio effects and filters in this sequence:
- Denoise
- Noise Gate
- Compressor
- EQ filtering
- Limiting
One of the biggest rules you must follow to get a noise gate filter to work properly is to NEVER apply the noise gate AFTER compression. To do so, will render the noise gate completely useless, as you are first boosting the audio signal and then it simply will not work without cutting into the actual audio you want to keep in your mix. So make sure you add the noise gate after any denoise filter and BEFORE adding compression to your track.
Another important point you must remember is that your microphones MUST be set up correctly. This includes your input gain settings. If you are using a mic that uses phantom power, you must ensure your input gain is not set too high. If it is, you will also have trouble with the noise fate filter as you will be boosting the volume of everything in the room, including unwanted noise.
A better approach to boosting an audio signal in a podcast if the levels are too low is to have your speakers move their microphones closer to their mouths and lower the input gain. On a Rodecaster Pro mixer, this ends up being an input gain setting around 11-14, with the microphones about 2 inches from the speakers’ mouths. Conversely, if you had their mouths 5-8 inches from the mics and the input gain set to 25-33, you would hear an “unsightly” amount of room tone and would be picking up the other person’s voice so loudly, that the noise gate becomes pointless to use. Another benefit of lowering the input gain is that you can now afford to have the mics very close to the speaker’s mouth without excessive plosive noises (Ps and Bs) being overwhelmingly loud in the lower frequencies.
You can play around with the input gain settings and find what you feel works best for you.
How to Adjust the Noise Gate
So you’ve set your noise gate up but are noticing words are getting chopped at the start or cut off at the end. What to do? This is where you will need to tweak the noise gate filter settings until you find the right mix of threshold, attack, release, and hold. If your noise gate is too aggressive, your attack may be working too fast. Try increasing the attack time from 1 ms to 5 or 8 ms. Similarly, if the ends of words are getting clipped, you can increase the release time. Small increment changes tend to work better than huge adjustments.
It is important to sample various parts of your recording as well to ensure your threshold is not set too low or too high. If the threshold is excessively high, words will become choppy and distorted. If it is too low, it will be as if the noise gate is not even on; you will hear the background noise you are trying to remove.
You will now find that after a noise gate has been applied, your compressor will work much more effectively, as it does not magnify the unwanted noises in your recording; only the speaker’s voice will be raised to a point of clarity that will sound better to the ears!
