Upgrade Manual

Appendix A: "Audio Plugins"90
This plugin works like a high-frequency limiter— limiting loudness of high
frequencies without affecting low frequencies.
Frequency:
Adjust the crossover point for the De-Ess function. Frequencies
below this setting are not limited, and freqencies above are limited.
Threshold:
The high frequency limit threshold. Zero dB would offer no
limiting, and –96 dB would cut almost all high frequencies out of the signal.
Loud sibilance can be rather quiet compared to the lower frequencies.
Threshold may need to be set pretty low to get the desired result.
Release:
The time required for the high-frequency limiter to recover. A short
release time may "bounce back" too fast after a fricative. A long release time
may "pump" the highs too much.