Although Ableton Live doesn’t have a dedicated De-Esser plug-in, it has a serviceable De-Esser preset that uses Lives Compressor. Simply go to the list of presets for Compressor and load the Ableton Deesser Preset onto a track.
In this preset the sidechain EQ is activated. Enabling this section causes the compressor to be triggered by a specific band of vocal frequencies, instead of a complete signal. I personally prefer the EQ filter type to be changed band pass as seen in the screen shot above. You can then use the Freq dial to zero in on the sibilant frequencies. The Sidechain Listen (headphones button) between the external and EQ sections allows you to listen to the sibilant frequencies to make this adjustment easier.
It is then simply a case of adjusting your Threshold until the required amount of De-Essing is reached.
Deesser
The human voice exhibits prominence to different degrees in the high mid region (4-10KHz). This is referred to as sibilants. This over-emphasis can cause audible distortion in some devices, even though it may not appear that prominent.
Sibilance – def. – A sound with an exaggerated “s” and “shh” caused by a rise in the frequency response around 4-7kHz. Most noticeable on vocals and cymbals.
A de-esser is a device based on a compressor, but it is frequency dependent.
Using De-essing Effectively
To use de-essing most effectively, insert the De- Esser after compressor or limiter plug-ins. The Frequency control should be set to remove sibilants (typically the 4–10 kHz range) and not other parts of the signal. This helps prevent de-essing from changing the original character of the audio material in an undesired manner.
Similarly, the Range control should be set to a dB level low enough so that de-essing is triggered only by sibilants. If the Range is set too high, a loud, non-sibilant section of audio material could cause unwanted gain reduction or cause sibilants to be over-attenuated. To improve de-essing of material that has both very loud and very soft passages, automate the Range control so that it is lower on soft sections.