Dynamic Processors

This is an assignment for the Coursera course Introduction to Music Production


Hi, I’m Sungwon. I grew up in the United States, have been in South Korea the past 9 years and am now living in France for the time being. In this post, I’ll be describing dynamic processors and their common parameters:  threshold, ratio, attack and release.

Dynamic Processing

Dynamic processing acts on the amplitude of an audio signal. There are two main types of dynamic processing: dynamic compression and dynamic extension. Dynamic compression decreases the dynamic range, essentially decreasing the amplitude of the “loudest” parts and decreasing the “quietest” parts. Dynamic compression increases the dynamic range, essentially increasing the amplitude of the “loudest” parts and decreasing the “quietest”.

dynamic processing

Conceptually, dynamic extension increases dynamic range (left arrows), dynamic compression reduces it (right arrows)

Dynamic processors act on amplitude according to certain algorithmic rules. Common dynamic processors include Compressors, Limiters, and Gates. Most of these dynamic processors can be configured using threshold, ratio, attack and release parameters.

a3 gate

A Gate plugin in the Ardour DAW displaying threshold and attack parameters among others.


threshold and ratio

Conceptual diagram of threshold and ratio in a compressor as they relate to input (x-axis) and output (y-axis) levels (source)

The threshold is the amplitude level at which the dynamic processor is activated.  For example, in a compressor, all input above that level is subject to compression and all below is not.


The input:output ratio is the degree to which the dynamic processing is applied to the signal. A ratio of 1:1 represents no dynamic processing effect, the level of the input and output are the same. 2:1 would represent a 2-fold reduction in the signal amplitude.

a4 compressor

A compressor plugin for the Guitarix Linux guitar effects processor with knobs for ratio, threshold, attack and release


The attack parameter controls how fast the processing is applied once the signal has crossed the threshold. An attack time that is too short  (i.e. fast) could cut off the transients resulting in a less-“human” sound. An attack time that is too long (i.e. slow) could take too long to act on the signal, resulting in no significant processing of the signal.

Mark Bass Compressore Pedal


Release is the complement to attack. It controls how long it takes for the processing on the signal to cease once it has dropped below the threshold. A faster release time can result in a kind of “pumping” effect on the signal.


Thanks to my fellow students for peer reviewing this assignment!

Originally, I wanted to do a screencast for one of the demonstration assignments. I was able to configure PulseAudio and Jack correctly so that I could record to the screencast software and use my DAW Ardour at the same time, but the audio was so bad with my laptop’s built-in microphone that I decided against it (I even tried to use a gate to filter out the noise in the audio).