Processing
Threshold is the level at which a dynamics processor, such as a compressor, limiter, expander, or noise gate, begins to act on an audio signal. It defines the point where the processor detects that the input has become loud or quiet enough to trigger gain reduction or expansion.
In a compressor or limiter, the threshold sets the signal level above which compression begins. When the input signal exceeds this level, the processor reduces its gain according to the selected ratio and timing settings. Signals below the threshold remain unaffected. Setting a lower threshold increases the amount of compression applied, while a higher threshold limits processing to only the loudest peaks.
For example, if a compressor’s threshold is set to –10 dB, only portions of the signal louder than –10 dB will be reduced in level. The amount of gain reduction depends on the ratio, while the attack and release times control how quickly the processor responds to and recovers from these changes.
In limiters, the threshold is typically set just below the system’s maximum output level to prevent clipping. In expanders and noise gates, the threshold operates in the opposite direction — when the signal falls below the threshold, the gain is reduced or the gate closes, effectively attenuating unwanted noise or background sounds.
Correct threshold adjustment is crucial for transparent and effective dynamics control. A threshold set too low can lead to over-compression and loss of dynamics, while one set too high may fail to tame peaks or inconsistencies. Engineers often monitor gain reduction meters while adjusting the threshold to achieve the desired balance between control and natural sound.
