Vocal De-Essing During Mastering: Using Frequency Measurement

Although the English language has its fair share of pleasantly harmonious phrases and sounds, the ‘ess’ sound isn’t one of them.

When properly balanced and mixed, the very common ‘ess’ sound (also referred to as sibilance) doesn’t present many problems.

If left unattended to, it can wreak havoc on your mix and master, leaving you with a finished product that’s unpleasant, shrill, and perhaps even unsuitable for a commercial release.

Fortunately there are many ways to identify the frequencies that need to be attenuated, and a slew of tools designed specifically for this purpose.

The techniques discussed here will offer the best and quickest way to identify the frequencies at fault, as well as establish a way to measure sibilance as it relates to instrumentation within the same frequency bandwidth, using professional and unprofessional examples as reference.

Furthermore, it will be demonstrated how you can test your mixes using frequency analyzation.

Although the tools used for the purpose of de-essing were mentioned above, their functionality will not be delved into, as this information is readily available in their user manuals and in notable online articles - instead the primary focus will be on measurement.

Vocal Showing Ess

The first step to quickly determining the frequency range of the ‘ess’ sound you’ve recorded is by using a frequency analyzer. The results will be best if you use the highest detail setting for the analyzer.

In the picture above, an individual vocal take is being measured, in which the ‘ess’ sound can clearly be seen at roughly 5200 Hertz.

On the left side of the image, notice the scale measuring the amplitude of the signal - this will be important when comparing the sibilance signal strength to the instrumentation signal strength of the same or similar frequencies.

For the time being, it can be noted that this particular ‘ess’ is relatively strong, as its signal nearly matches that of the vocal mid-range. In addition, note that this vocal take has not been processed in any manner.

Instrument with Ess

In this photo, the stereo master file is being measured, in which the unprocessed vocal is having a negative effect on the overall balance.

The ‘ess’ is peaking at nearly 0dB on the scale; however, the surrounding instrumentation is averaging -20dB. This demonstrates an increase of nearly 20dB when the sibilance is present.

This begs the question, is the ‘ess’ sound more important than the instrumentation, or the harmonious sounds of a vocal performance? In truth, it isn’t. Considering that sibilance is more or less a matter of pronunciation, and doesn’t serve much of a purpose musically, its prevalence in a mix should certainly be limited.

With that in mind let’s take a look at professionally recorded, mixed and mastered tracks, to get a good sense of the usage of sibilance, and the restraint with which it is typically administered in a mix.

Kacey Musgraves Ess

Kendrick Lamar Ess

In the top photo of the two shown above, we have a measurement of Kacey Musgraves’ track ‘Merry Go Round,’ showing just the instrumentation.

Notice the amplitude of the higher frequencies, particularly that of 5k Hertz to 8k Hertz. It’s amplitude ranges from -20dB to -25dB respectively on this particular scale.

Now take a look at those same frequencies in the second measurement in which her vocal is present during a moment where the ‘ess’ sound is being sung.

There is a slight increase at roughly 8k Hertz, from -25 dB, to approximately -17dB.

This demonstrates an increase of 8dB - significantly less than the previous example and immeasurably more enjoyable when listened to.

Now let’s take a look at one more example to demonstrate how sibilance is controlled in a professional recording, and how this control is administered across various genres.

Instrumental - Kendrick Lamar

The track ‘Sing About Me’ offers Kendrick Lamar plenty of opportunities to deliver an overbearing ‘ess’ sound - the repetition of the word ‘sing’ throughout the chorus could certainly have resulting in multiple unpleasant moments; however, the sibilance is blended tastefully, allowing the high end to retain an incredibly smooth characteristic.

Take a look at the measured instrumental above, then the measured track with vocals at the precise moment Kendrick utters sing:

Ess - Kendrick Lamar

Clearly, the difference is miniscule - the primary change being a 5dB gain increase at 10k Hertz.

This goes to show that even in Hip-hop, a genre in which the production is known for a notably prevalent low-end and high-end, the ‘ess’ sound is recognized as a part of vocal pronunciation and treated as such.

Now that you understand how frequency analyzation can be used to identify the bandwidth of the ‘ess’ sound, and have seen how professional recordings limit the presence of superfluous sibilance, you can test your mixes and see how they compare.

To test the sibilance of your mixes, first add a frequency analyzer to your master output, preferably with the highest measurement detail possible.

Then solo your vocal track, and observe the frequency of the sibilance when it occurs. Next mute your vocal track while the instrumental plays, and observe the bandwidth that your sibilance occupied previously.

Lastly, play the entire song, and compare the amplitude of your vocal sibilance with frequencies of the instrumental.

If the ‘ess’ sound in your mix has an amplitude significantly greater than that of your instrumental, reassess your mix, and take the necessary steps to de-ess your vocal. This is a process that can easily be implemented whenever you feel unsure about how the ‘ess’ sound is affecting you mix.

Conclusion

Using these vocal de-essing techniques can take you closer to a finalized mix that’s ready for mastering.

What techniques do you use for vocal de-essing?