Using a De-Esser…
It can be useful to use a de-esser or high-EQ focused side-chained compressor or similar alternative on close mic’ed vocals, bright acoustic guitars, sharp cymbal crashes, and synths that have sharp high frequency transients.
It’s best if you address the high frequencies of vocals and other instruments at the mix stage if they sound harsh or clash with other notes/chords/timbres.
A mastering engineer has specialized reduction tools to deal with overly sibilant mixes. The trouble is that in the mastering stage, all the instruments are blended together and we have less control over the sibilance of single instruments. If we reduce sibilance from a particular offender, there can be unavoidable touches to the other instruments in the same frequency range.
If you don’t feel comfortable doing it yourself, consider talking with your mastering engineer about stem mastering. This will allow your mix to hold its integrity while giving the mastering engineer far more options to tame these wild horses.
I specialize in stem mastering!
Please let me know if you need help.
This is a female vocalist singing the word “us”.
This part is the “sss”. You can usually tell the higher frequency sections of sound waves by how dense the part looks. More highs means more up and down motion that the wave quickly makes, so it looks denser.
Examples of DeEssers:
This one is from Waves.
These can be set to trigger on frequencies in the high range where these “sss”/harsh guitar string bite/cymbal crashes, etc… sounds reside.
It’s focus filter was set around 3kHz.
The DeEsser will turn down all sounds that get louder than the threshold.
Don’t over do it. More than 6-10dB reduction, in some cases, can make people sound like they have a lisp!!!
Here’s another version from FabFilter.
It has a way of focusing on things that are particular to vocals, instruments, or full mixes. It also lets you specify a range of operation, and a choice of split band or wide band gain reduction.