How To Reduce and Eliminate Sibilance From Vocals

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How To Reduce and Eliminate Sibilance From Vocals

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It happens to nearly everyone — you’re listening to a vocal track and you notice harsh, hissing “S” sounds that you didn’t catch during the recording.

That sound, known as sibilance, can detract from an otherwise great vocal performance. Let’s look at how to reduce sibilance from vocals.

The best way to reduce sibilance from an already recorded vocal track is to use a de-esser, which cuts the frequencies that cause the sibilant “S” sound. You can also work with a vocalist to reduce sibilance during a performance and can use mic placement to minimize it, as well.

Let’s examine what sibilance is, what causes it, how to prevent it, and how to reduce or eliminate it from already recorded tracks.

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What Is Sibilance On A Vocal Track?

The word comes from the name of the sounds that produce it. Known as sibilant fricatives, these sounds — s, z, sh, and zh — create turbulence in the vocal tract, and that causes a distinctive hiss-like sound.

Some sibilance is normal, and it can even help us understand speech, but too much sibilance can create a harsh, unpleasant tone.

In terms of what sibilance overload — when the sibilant sounds overwhelm the other parts of the track — will show up as on your track, it will be harsh sounds in the upper parts of the audible frequency of 20 Hz to 20 kHz — particularly above 5 kHz.

It’s worth noting that sibilance is a particular kind of harshness, and needs to be treated differently than other kinds. The same is true for prevention: Different vocal techniques are needed than used to prevent other pronunciation and articulation issues.

One thing to consider is that no two vocalists or microphones are the same and because one EQ, compression, and de-essing approach worked with one vocalist, doesn’t mean it will work again in the same way for someone else.

Each performer’s voice is a unique project of its own. Don’t assume past practices will work with this new vocalist, but do let your experience guide you.

Also remember that sibilance and harsh vocals do not always go hand in hand.

Sibilance is created with strongly spoken consonants that produce air from the lips and tongue.

Harsh vocals can be created without sibilance and can be associated with the pitch of a vocalist, the timbre they chose or a host of other issues.

How To Get Rid Of Sibilance

Like we saw above, some sibilance is normal and even good. You need strong constants to be understood.

But just like with the plosive “pop” caused by P sounds, too much sibilance can sound harsh and even detract from the listening experience. There are ways to avoid this sibilance overload, though.

You can use post-processing tools to get the right sound during the mixing process, or you can spend some time and effort during recording to make sure you avoid sibilance overload in the first place.

It should be pretty obvious why it’s better to fix as much as possible while recording — or even before! — as opposed to when mixing. That isn’t always possible, so we’ll look at some ways to prevent it and some ways to fix it when it happens.

How To Reduce Sibilance When Recording Vocals

There are a few techniques you can try to reduce sibilance when you’re recording a vocal track. Some have to do with how the track is recorded, while others require the vocalist to make some changes.

Microphone Techniques To Reduce Sibilance

Your microphone choice is going to have a big effect on the amount of sibilance in a vocal track.

Sibilance is also in the upper frequency range, so microphones that emphasize that range can tend to produce a more sibilance on vocal tracks that others. That is part of the reason one common piece of advice is to choose “darker” sounding microphones.

Microphones that emphasize higher frequencies have a bright, clear sound that can be great — until it sounds like you enlisted a chorus of snakes for backup vocals.

Dynamic and ribbon microphones, both of which are commonly used for vocals, are good choices, because both have more response to lower frequencies than higher ones — hence their “darker” sound.

Large diameter condenser microphones, which tend to emphasize lower frequencies, can also be a good choice. The airy tones you get from a small diameter condenser microphone can really bring out sibilance, as well, so you might want to avoid those.

Microphone placement also has a huge effect on sibilance.

Part of that has to do with the interaction of how sibilant sounds travel and the way microphones pick up sound. Sibilance is most pronounced close to the mouth and in a direct line with the path of the breath when singing.

If you back a microphone away from the vocalist and move the capsule either above or below the line of the mouth, you can drastically reduce sibilance. A reasonable starting point is to have your source 6 to 10 inches from the mic.

Distance itself, as well as the exact placement of the microphone capsule can also be dramatically effective at reducing or almost entirely eliminating sibilance with a well-trained vocalist. That’s because higher sounds travel less far than lower ones.

Sibilance is at the upper range of frequencies, usually between 3 kHz and 9 kHz, though it can hit even higher frequencies.

You can also tilt the microphone off axis, meaning move the capsule so it faces the vocalist at an angle instead of straight on. This will color and darken the sound, again, helping to cut back on sibilance.

Your microphone choice should be dictated by what you have available and the room you’re using. A ribbon microphone, for example, is both very sensitive and often very expensive.

It requires higher gain than other microphones and that can pick up hiss or other ambient noise, and trading sibilance for a noisy, crackly vocal track, or one contaminated by sound bleed, doesn’t make a lot of sense.

The same is true of some condenser microphones. Because they require a higher gain, they can be noisier than dynamic microphones.

Whether the off-axis microphone trick will work also depends on the polar pattern of the microphone, or the shape of the area the microphone picks up sound from. Cardioid pattern microphones, which are the most commonly used for vocal recordings, offer a big change between on and off axis sound.

Omnidirectional pattern microphones, on the other hand, have very little change because they are equally sensitive in all directions.

Vocal Techniques To Reduce Sibilance When Recording

Start out with realistic expectations in this realm. How much effect basic vocal technique changes will have depends a lot on the experience and ability of the singer.

No matter how much or little experience your vocalist has, though, there are some things to try to make sure the performance starts out with as little sibilance as possible.

First, make sure they understand the proper distance to stand from the microphone. The best starting point is 6 to 10 inches.

One good way to show the singer where to stand is to have them hold up their fists and use those as spacers.

There should be one fist’s space between the microphone and the pop filter and another fist’s space between the singer’s mouth and the pop filter.

There are a lot of videos out there like this one, which explains vocal sibilance and how to reduce it as a singer.

If you’re running into a lot of sibilance and microphone choice and placement aren’t solving it, consider showing them some videos like that, which offer explanations of techniques to cut back on the sibilance produced.

A more experienced singer will be able to put the things the videos talk about into practice more quickly than a less experienced one, but singers of all levels can definitely benefit from the techniques.

But, again, don’t expect vocal technique alone to solve the problem, especially if you’re working with a less experienced or untrained vocalist.

Use The Pencil Trick To Reduce Sibilance

In a pinch, a trick that is often used in studios to cut back on plosives can also help reduce sibilance, at least somewhat.

The “pencil trick” involves holding a pencil, pen, straw, or any other round object to your lips when singing. Because sibilance is caused by the particular disturbances in airflow caused when making certain sounds, interrupting that airflow can limit their impact.

This can be finicky, and it can definitely be distracting. Don’t expect the get the best vocal take the first time you suggest using this trick.

You might want to suggest the vocalist practice with that technique, if you have the the time, so they can get used to it.

How To Use EQ To Reduce Sibilance In A Vocal Track

You can’t always get rid of sibilance when laying down the track, whether you didn’t hear it during the recording or maybe you weren’t involved in the recording in the first place.

EQ is everything to reduce sibilance and harshness. In fact, before you take the last steps to remove sibilance, you should always apply your EQ settings.

With the right EQ settings, you can create a narrow bandwidth and sweep across the EQ to find the harsh places in the vocals. Make the bandwidth as narrow as you can.

Be careful while doing this, as it gets loud and can be very hard on your ears. There are some DAWs that have an inverse frequency EQ, where you can invert the other frequencies to be nonexistent and work with the desired frequency without turning it up.

With Protools on PC, if you press SHIFT + WINDOWS KEY while adjusting any knob, it will solo the frequency. While sweeping, you’ll hear the frequencies that are unpleasant and they’ll become even more unpleasant.

Some say these frequencies sound like feedback and bite the ear. In these frequencies, keep your bandwidth tight and turn them down.

Here is an example of sweeping with the fifth band in the screenshot below. Remember, while sweeping across the EQ, the track must be playing so you can hear the frequencies that need adjusting.

Make sure the whole mix is playing because frequencies that may sound harsh soloed may fit just fine in the full mix. The sixth band is an example of where we isolated a frequency that needed to be turned down.

Now, you can do this with several bands. Sweep, find the harsh spots, tones, frequencies and reduce. Remember, all vocalists and microphones are different and adjust accordingly.

If your main goal is to reduce sibilance, concentrate your EQ sweeps above 5 kHz. Be very careful about how much adjustment you make.

Too much of a reduction in that area can make it sound dull and lifeless, without any sparkle, but a small roll off in the right place can have a similar effect to choosing a darker microphone in the first place. That can go a long way toward reducing sibilance.

Now that you’ve taken care of the other harsh sounds and eliminated some sibilance, let’s look at the last steps to take.

How To Remove Sibilance From A Vocal Track By De-Essing

De-essing is the final step in our fight against sibilance and is exactly what it sounds like — reducing the sibilant ess sounds in a track.

It can be done in a few ways. The first is to go through a vocal track, listen along for sibilance, and look at the waveform until you find the characteristic “football” shape that sibilance can cause.

In each instance, highlight that part of the waveform and reduce the gain.

If you have enough experience, it would be quite effective, but it is clearly going to be very time-consuming.

You can achieve something similar by using the automation features on your DAW to adjust the gain at certain points. This is less time-consuming, but still not a quick process.

A much more common solution is to use a de-esser plugin, which uses a combination of EQ and compression to cut back on sibilance in the track.

A de-esser can help you isolate the high frequencies where those consonants are striking and compresses those frequencies so they become less harsh. The de-esser is a great automated tool to help with sibilance issues.

De-essers typically have the following functions:

  • Detection/Suppressor
  • Sensitivity
  • Strength
  • Smoothing

Start out by finding the worst sibilance overload in your vocal track and use that to target your de-esser.

You’ll need to find the frequencies that are causing the most trouble, often ranging from 3 kHz to 9 kHz. Let’s say the frequency being affected the most in this instance is 7.5 kHz.

Now you can begin adjusting sensitivity. The sensitivity is the threshold you’d find in any compressor.

You’ll want to find the sweet spot in between compressing too much and not compressing enough. With a de-esser, you can make your consonants disappear entirely, so you must use with caution.

When using a de-esser more than you should, the singer will begin to sound slurred or begin to sound as if they had a lisp.

The strength then adjusts how much of the chosen frequency you would like attenuated or reduced. Last but not least is smoothing. Smoothing is the attack time you would like the de-esser to perform its compression.

Don’t forget EQ can help a lot with sibilance issues. Make sure you EQ first, and try to eliminate the harsh frequencies before running an automated compressor like a de-esser.

In fact, you should run any other compression before a de-esser, as well. Think of it as the last step in your EQ and compression process.

When using a de-esser, consider making several small adjustments to the track, applying each in turn, as opposed to making a big change at one time. This can help reduce artificial sounding noise artifacts that can arise.

Your process should look like this:

  • Start with EQ and Compression
  • Isolate harsh frequencies
  • Adjust threshold of de-esser
  • Adjust strength; apply too much and back off gently until natural sounding
  • Adjust smoothing or attack time; quicker attack will reduce harsh sibilance sooner

Conclusion

We already looked at why it might be important to do what you can to reduce sibilance during the recording, as opposed to having to fix it when mixing.

As you can see, even using automated de-essers can actually be quite time consuming, because of the small changes needed to balance between removing sibilance and making the vocal track sound unnatural.

But while you’ll definitely save time by trying to reduce sibilance during the recording, don’t be surprised if you have to do some adjustment in the mix, as well. But the fact you’ll be able to make smaller changes will end up producing a better overall track.