Is there a free plug-in de-esser compatible with audacity?
There’s two. There’s the classic, legacy, senior DeEsser.
And the newer DeSibilator.
Under some conditions of severe Essing (SSister SSuzy SsimulateSS) DeEsser would turn Essing into “Effing.” (FFister FFuzy) Not quite as bad, but not natural, either.
DeSibilator changes settings to avoid that.
I use a tool nobody likes: Analyze > Plot Spectrum. Louder is up. Pitch increases left to right. Bass notes on the left. Essing produces a “haystack” in the display in the wrong place. That’s the bump on the right. The beginning and ending of that bump are the two frequency settings in both tools.
The object of successful DeEssing is to smooth out that hump.
No more ice pick in the ear sounds.
I made up a “before” illustration.
The two yellow dots are the extremes of the hump and those are the values (from the bottom scale) you put in the DeEsser “between” frequencies.
Each microphone that produces Essing does it a slightly different way and produces a different hump. The advertisements all promote this is sounding more “professional.” It makes my ears bleed and it affects many other people the same way.