18. Defining, Identifying, and Maintaining Resonant Frequencies in the Voice
No matter what instrument you are recording, how it was recorded, or what hardware it was recorded with, you will always capture unwanted frequencies. That's what this entire series on frequency has lead to, identifying and properly removing unpleasant sounds. While there's more to it than this, one type of very unpleasant sound is a resonant frequency, which is simply defined as a build up on energy in a located area on the frequency spectrum. There can be several of these resonant frequencies in a recording, and once we know they're there and have the tools and abilities to properly identify them, we can transparently remove them, leaving behind a more pleasing arrangement of sounds.
In this episode we define in greater detail resonant frequencies, why they're bad, how to identify them, and how to remove them.
What are resonant frequencies?
Resonant frequencies can be simply defined as a build up of frequencies in a localized area in your spectrum. There's a lot to resonance of a physical object which you can learn more about here, but for the purposes of this article and episode, we'll be talking about the overwhelming boosts in certain frequency ranges in the human voice.
Why are resonant frequencies bad?
Resonant frequencies tend to be overwhelming and pretty loud. They have a tendency to mask other frequencies that may attribute to clarity, presence, and intelligibility. Another adverse effect is it can impact the overall loudness of your podcast. Your meter might read -16LUFS but your podcast can still sound quieter than others. The reason is many resonant frequencies tend to live in the lower end of the spectrum, and this can mask midrange and intelligibility. Your may be responding to all the low end power while your presence frequencies are actually quite low. That will give the impression that your podcast isn't very loud and just being drowned out by lower range frequencies.
How to identify resonant frequencies
There are many ways we can identify resonant frequencies starting with our ears. This can be quite hard for some new folks, and there are several tools that can help with visual cues. A cheap and easy way is any affordable spectral analyzer. I used to use the PAZ Analyzer by Waves before I went full force into Fabfilter ProQ3 as my main equalizer. ProQ3 has a built in analyzer that shows much finer details. Another feature of the equalizer is it will offer suggestions on problem frequencies, which are also shown by the peaks in the frequencies themselves.
A tried and true method of finding harsh and overwhelming frequencies is a method called "sweeping". With a high Q, crank the gain on that narrow band and move it up and down the spectrum. None of this will sound good, but you'll come across some ranges that REALLY shoot out and are aggressively louder than others. Odds are, these are your resonant frequencies.
How to fix resonant frequencies
This is the easy part! Once we've identified the problem frequencies, just start attenuation that junk! Use your equalizer to reduce those ranges, but make sure to not overdo it! While those lower frequencies have a tendency to become overwhelming, they're also very important so don't remove too much. Use your ears!
Last thing! I've been demoing a tool called Soothe 2 by eoksound that identifies and suppresses resonant frequencies dynamically in real time. It's easy to overdo it with this plugin, but when set up properly, it's super powerful and does a ton of the heavy lifting for you. You can demo the full plugin for 20 days here.
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My Signal Chain
Audio Interface: Apogee Ensemble
Microphone: Shure SM7b
Headphones: Audio-Technia ATH-M50x
Earbuds: Klipsch R6i II
Studio Monitors: Yamaha HS7
Mic Stand: Rode PS1A Boom Arm
IzoTope RX6 Mouth De-Click
IzoTope RX6 Voice De-Noise
Waves Vocal Rider
Rider Waves CLA-2A
Waves L2 Limiter
Waves WLM Meter
Waves Durrough Meter
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Midroll Song: Road Trip by Joakim Karud
Closing Song: Clouds by Joakim Karud