DeEsser is a frequency-specific compressor, designed to compress a particular frequency band within a complex audio signal. It is used to eliminate hiss (also called sibilance) from the signal. The advantage of using DeEsser rather than an EQ to cut high frequencies is that it compresses the signal dynamically, rather than statically. This prevents the sound from becoming darker when no sibilance is present in the signal. DeEsser has extremely fast attack and release times.
When using DeEsser, you can set the frequency range being compressed (the Suppressor frequency) independently of the frequency range being analyzed (the Detector frequency). The two ranges can be compared in the DeEsser Detector and Suppressor frequency range displays. The Suppressor frequency range is reduced in level for as long as the Detector frequency threshold is exceeded.
DeEsser does not use a frequency-dividing network—a crossover utilizing lowpass and highpass filters. Rather, it isolates and subtracts the frequency band, resulting in no alteration of the phase curve.
The Detector parameters are on the left and the Suppressor parameters are on the right. The center section includes the Detector and Suppressor displays and the Smoothing slider.
DeEsser Detector parameters
Detector Frequency knob and field: Set the frequency range for analysis.
Detector Sensitivity knob and field: Set the degree of responsiveness to the input signal.
Monitor pop-up menu: Choose the signal type that you want to monitor. Choose Det(ector) to monitor the isolated Detector signal, Sup(pressor) to monitor the filtered Suppressor signal, Sens(itivity) to remove the sound from the input signal in response to the Sensitivity parameter, or Off to hear the DeEsser output.
DeEsser Suppressor parameters
Suppressor Frequency knob and field: Set the frequency band that is reduced when the Detector sensitivity threshold is exceeded.
Suppressor Strength knob and field: Set the amount of gain reduction for signals that surround the Suppressor frequency.
Activity LED: Indicates active suppression in real time.
DeEsser common parameters
Detector and Suppressor frequency displays: The upper display shows the Detector frequency range. The lower display shows the Suppressor frequency range (in hertz).
Smoothing slider and field: Set the reaction speed for the gain reduction start and end phases. Smoothing controls both the attack and release times, as they are used by compressors.