From Audacity Manual
Hard Limiter can also sometimes be used to remove stubborn clicks that peak well above the general level of the waveform. See the tutorial Sample workflow for LP digitization for tips on using Hard Limiter to remove clicks.
- Accessed by:
The amplitude level above which the input signal is processed. If the Wet level and Residue level settings are left at default, the peak level of the result will be clipped down to this level.
The amount of the clipped signal that is fed to the output. It thus acts as a volume control for audio below the dB limit. If left at default level of 1.0, all sounds below the dB limit are fed to the output. At settings below 1.0, the volume of the result will be reduced.
This allows a proportion of the signal that has been removed by clipping to be added back to the output. By default the value is 0.0 and so all of the clipped signal is discarded. By raising this level, some of the clipped signal will be restored, making the limit softer. More peaks and troughs of the original waveform will be retained, and the resultant volume level will be higher than that set in the dB limit.
This effect supports Real-time preview - effect settings can be changed while playing and listening to the result in real-time. Text-based button controls are provided as in the image above. The Enable checkbox acts like a live "Bypass" control. Uncheck the checkbox to hear the audio without the effect applied, and recheck the box to hear the effect applied at its current settings.
Thebutton accesses choices to add, delete, import or export presets for this effect and to set options for this effect.