You’re about to learn how to keep those sounds from sneaking into your recording takes and how to deal with the few that still make it in, so save that perfect take! It might still be salvageable by the end of this tutorial…
“How come every time I say word that features a ‘B’ or ‘P’ syllable, it sounds like I’m hitting a kick drum with my voice? And then every time I use a word with an ‘S’ or a ‘T’ it sounds like a snake is hissing through a football coach’s whistle?”
Knowing why this happens is just as horrible as trying to explain the problem to someone without sounding crazy. You can move from looking like a lunatic to being an insightful, confident recording engineer just by knowing the words that represent these sounds.
And these words are sibilance for the hissing and plosives for the booming sounds.
Don’t drop those terms on anyone without knowing more about it though, because the next natural set of questions is going to be what they are, what causes them, how to fix them before recording them, and how to fix them in the mix.
The answers have a lot of angles to them but fortunately they aren’t complicated. Let’s just right into it. One read through this article and you’ll never encounter sibilance and plosives you can’t handle ever again.
Please pay attention, though. The overall solution requires the combination of all of these individual solutions. Not only do you need them all, but you can’t skip any of them if you want to record crystal clear vocals.
Any quality discussion concerning this topic should start with the question, “What is sibilance in audio?” and directly lead into “How to get rid of sibilance,” and the same goes for plosives. Let’s cover both.
What is Sibilance in Audio? And Plosives?
We already talked about the laymen’s version which is the booms and hisses that sneak into recordings due to certain syllables being spoken. Let’s dig into the technical side of this question now.
High Frequency Hiss & Low Frequency Booms
Both plosives and sibilance in audio are the result of an increased amount of air being pushed out of the lungs, vocal cords, and mouth at a stronger amplitude. This happens due to the shape the mouth has to take before speaking these syllables. Try it out yourself.
The main culprits are:
- For Plosives: syllables that start with B and P.
- For Sibilance: syllables that include S and T.
Of course, based on the speech pattern and style of each individual, there may be more or less letters that cause these issues.
So play with B and P. Any syllable starting with those letters demands that your lips be squeezed together slightly to allow a build up of air pressure behind them before releasing them in a pop. That’s precisely where the pop filter gets its name from.
Try the same with any syllables that include S and T and pay attention to how your tongue is pressed against the back of your teeth and front portion of the roof of your mouth. This creates a small canal for air to slide through to create a higher frequency sound, just like what occurs when you whistle.
Why is it Only a Problem in Audio and Not in Real Life?
As people begin to think about this situation, they realize that while it’s a common problem in audio recordings, plosives and sibilance are rarely a problem in real life. Why is this the case?
The answer is that it’s not the case. Everyone records vocals by close miking for the most part. That means the microphone’s diaphragm is very close to the source of the sound where it originates with the most strength.
If you let someone place their mouth right up to your ear and speak quietly, even that’s too strong for comfort. And if they start popping off any plosives or sibilance, you’ll realize quickly that it’s the distance between the source and the recording device that captures these sounds.
In the Waveform & Frequency Spectrum
As you sit down to the mixing desk and start looking at these wave forms, you’ll find that sibilance and plosives are both isolated to a certain range of the frequency spectrum. Rough guides are as follows:
- Sibilance: 6 kHz – 8 kHz and sometimes higher
- Plosives: 150 Hz and lower, but sometimes as high as 200 Hz
This should give you plenty of hints on how to deal with these sounds after they have been recorded. We’ll get to that, but first we’ll talk about how to avoid them altogether.
How to Get Rid of Sibilance
The goal is always going to be to not record these nuisance sounds in the first place. But even the most skilled recording engineer will let them slip in, and it’s not always their fault! The vocalist might be the kind who likes to rock back and forth, move closer and further away from the microphone, etc.
There are tricks to stop that behavior too when needed that we’ll share. But if you can’t solve it at the source, the mixing engineer will get a few tricks here as well to combat this plague that sickens our vocal tracks.
Let’s deal with each problem one at a time, but first a general tip for combatting both:
If you find that your vocalist has extraordinarily strong sibilance or plosives, instead of destructively interfering with the take before or after recording, try switching microphones. Large diaphragm condensers are highly sensitive. Try switching to a high quality dynamic microphone such as the Electro Voice RE-20.
Remember, what you don’t record can’t be a problem later. So let’s start during the tracking process.
Facing Off-Axis From Microphone
There’s not a lot that can be done before recording to reduce sibilance in a vocalist. Some have it worse than others. One common method that actually works for plosives as well is to set up the microphone so that the vocalist is facing off-axis from the diaphragm.
Imagine, as the vocalist, that this microphone was facing straight at you. Then the recording engineer walked into the booth and turned it to the left and then tilted it back slightly. You are now facing off-axis from the pickup pattern of the microphone, which is probably cardioid.
This makes it so the strength of your pops and hisses will be reduced because they are coming in at an angle instead of a full on front-facing collision. This is your first weapon against sibilance.
Using a De-Esser in Sibiliance Frequency Range
A De-Esser does exactly what it sounds like it does. It removes the “S” sound (the hiss). The way it pulls off this sorcery is by being a compressor with an equalizer side-chained to it.
This means that it functions just like a compressor would but only does it to the specific range of frequencies you’ve chosen. You can learn more about sidechain compression here.
You can buy a hardware de-esser but your DAW likely has a built in plugin that’ll get the job done. Just like a compressor, set the threshold at the proper point somewhere below what is considered “just right.” It will have a default range of frequencies somewhere between 6 kHz and 8 kHz that you can change if you want to match your vocalist.
So when the hiss of sibilance spikes in that frequency range and goes above your threshold, it will be reduced by the ratio you’ve chosen. It’s a compressor that acts on a specific frequency range. If you set this up on your track for one instance of sibilance, it should solve all of them on that take.
If you use a de-esser, it’s best to apply the effect before other equalization, compression, or spatial effects. You always remove the unwanted first before applying effects to what you want to keep!
Heads up. You’ll know you’ve gone too far with the de-esser if your vocalist develops a lisp that wasn’t previously there. Listen closely for this!
Now we shift the conversation over to…
How to Reduce Plosives
Your first weapon against plosives is the same as with sibilance. Try turning the microphone off-axis to reduce the power behind these pops. After that, follow these next steps in order and see which solve the problem.
Add each on as you go until it’s fixed. There’s no need to overdo it, as that will negatively impact your recording.
Buy a Plosive Pop Filter
If you don’t have a pop filter, you need one. It’s one of those non-negotiable items that should be hanging off of your vocal microphone’s mic stand. You’ll see a lot of do-it-yourself information on the web about using a wire hanger and creating a circle then wrapping it in panty hose.
This will work but it’s not something to do with professional recordings. It’s akin to using foam acoustic treatment instead of high density insulation. You’ll fix some issues and create a lot of others using materials not designed for acoustic purposes.
I personally have two pop filters on my mic stand and will pull up the second one depending on the vocalist. Rappers will often require a little more defense against plosives than will a softer singer. I use the kind that look like this:
These pop filters are designed to remove the booming sounds coming from plosives, unlike panty hose which are meant to keep your legs warm or hide your unshaven leg hair. I don’t know why they are worn actually, but don’t use them for pop filters! The cloth here is woven with the right material at the right density to only affect the lower registers of the human voice.
If you want to get fancy about it, I also like this pop filter, the WindTech PopGard:
Again, it really doesn’t matter which you use. If you want to visually impress clients, go for the sleeker looking ones like the WindTech. Both get the job done though.
Some of the best microphones for recording vocals come with custom built windscreens and even pop filters built into the shockmounts that are designed to not effect the frequency response of the mic. Adding another pop filter if necessary will be fine. Better that than pops!
Apply An Equalization Low Roll-Off
You’re going to be doing some amount of equalization anyways. Of course, the amount and type of EQ you’ll apply will depend on the mix and the vocal’s place in the song. As you make those decisions, see if the following plan fits into the overall picture.
When EQing out plosives, you’ll want to use either a low roll-off or just go ahead and slap on a high-pass filter, again depending on the mix. But the goal is the same, which is to reduce very low frequency sounds out of the vocals that don’t belong there or muddy up the mix.
Knowing that plosives generally exist around 150 Hz or lower, but occasionally reaching a tad higher to 200 Hz, figure out where you want to place your filter or roll-off.
A roll-off will need to start higher to effectively reduce the power of plosives. In this case you might want to aim for just taming the plosives before fixing it entirely in the next step.
But if you’re using a high-pass filter, you’re probably involved in a fairly thick or crowded mix anyways. You can likely get rid of plosives entirely in this way.
Check the back of your condenser mic. It may even feature a low roll-off switch that can help tame plosives for you.
Use Automation to Drop Plosive Volume
The final tip, and fortunately the last one to come in the sequence of attempts, is to use automation. It sucks because you’ll have to either ride the fader or listen and draw the automation paths on the screen using your mouse.
It’s not difficult, but just time consuming. It’s also your chance to get in there with scalpel-like precision and fix your vocal take up to perfection.
Explaining volume automation is beyond the scope of this article. The picture above should explain entirely what it is you’re going to do, which is go in and drop the amplitude of the pop to make it sit in the mix without annoying the listener.
That’s How to Get Rid of Sibilance & Plosives
You now are the master of the plosive pops and sibilance hisses. You know how to avoid them by not recording them at all, and when they do sneak in, you know how to get rid of sibilance and plosives with equalization and volume automation.
That’s it! Fear these dreaded problems no longer. Your own songs will come out better and your clients aren’t going to talk smack about you after they receive their final mixes! Knowing how to mix vocals beyond this one technique will help drastically too.
This article literally just made your life better and possibly made you a few million dollars over time. To thank me, share this with your homies using the buttons below! It’s all I ask and crave. Catch you during the next studio recording column post!