From Audacity Development Manual
- Accessed by:
The balance between the RMS and peak envelope followers. The followers use the amplitude variation information in the waveform to affect the gain applied by the compressor. The RMS follower is generally better for subtle, musical compression and the peak follower is better for heavier, fast compression and percussion.
Attack time (ms)
How soon the compressor starts to compress the dynamics after the threshold is exceeded, in milliseconds.
Release time (ms)
How soon the compressor starts to release the volume level back to normal after the level drops below the threshold, in milliseconds.
Threshold level (dB)
The level at which the compressor will start to apply.
The gain reduction ratio used when the signal level exceeds the threshold level. Higher ratios reduce the gain more.
You must move this control from the default ratio of 1:1 for the effect to apply.
Knee radius (dB)
The distance from the threshold where the knee curve starts.
Makeup gain (dB)
The amount of gain added to the processed result.
After applying the effect, this displays what was the original RMS (dB) level of the selection before compression.
Gain reduction (dB)
Displays the degree of gain reduction that the effect applied to the original selection, in dB.
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.
The Manage presets.button accesses choices to add, delete, import or export presets for this effect and to set options for this effect. For details see