TAP DeEsser is a plugin for attenuating higher pitched frequencies in vocals such as those found in ‘ess’, ‘shh’ and ‘chh’ sounds.
Almost any vocal recording will contain ‘ess’ sounds, whether a strong vocal delivery, from bad recording, speech impediments or simply many ‘ess’ words spoken together.
Wind instruments and other musical instruments can also create shrill high-pitched noises. Audio engineers need to control these harsh ‘ess’ sounds in most recordings.

Credit: Tom Szilagyi