The Deesser tool is used to filter out unpleasant hissing sounds (sibilants) from recorded speech and song.   
The following sliders are available in the Deesser area:
Threshold

Specifies the level after which hiss is to be suppressed as a dB value. If this value is very low, even very quiet hiss is suppressed.

Attenuation

Specifies the extent to which hiss is to be damped if it is not filtered out completely.

The following sliders are available in the Response Time area: 
Attack Time

Specifies how long the hiss has to be in order to be detected.

Release Time

Specifies for how long the hiss is to be filtered.

 


Deesser