De-esser

A de-esser is a frequency-targeted compressor that clamps down on sibilance, the harsh hiss of S, T, and SH sounds that can spike unpleasantly in a vocal or dialogue track. It listens to a narrow high band, usually somewhere between 5 and 9 kHz, and reduces gain only when sibilance crosses a threshold, leaving the rest of the voice untouched. In dialogue editing and music mixing it smooths recordings that sound spitty, often a side effect of bright microphones or close mic placement. A mixer tunes the frequency to where the offending esses live and sets the threshold so the processing engages on harsh peaks but not on every word. Overdone, it gives a lispy, dulled vocal, so the goal is removing the sting while keeping speech crisp and natural.