I’m Peyton Haynie from Bay City, Tx. This is for week five of Introduction to Music Production at Coursera.org. I will be talking about the concept of dynamic processors and describing threshold, ratio, attack and release.
The concept behind a dynamic processor is simple: if it’s too quiet, make it louder. If it’s too loud, make it quieter. If there’s too much noise, bring it down. If there’s not enough noise, bring it up.
The threshold is the level at which the processor will start working. In a compressor, the threshold is the level where compression begins, with anything over that level being compressed. In a gate (or noise gate) the threshold is the level at which the unwanted noise is stopped, with anything above that level going through and anything below that level being reduced.
The ratio is the amount the audio signals are affected by the dynamic processors and will always be shown as a number:1. For example, a compressor with a ratio of 2:1 will reduce a signal that passes the threshold by half.
Attack and Release
When a processor starts working the attack determines how quickly the effect starts. The attack helps to control the transients of the audio signal, the spike in amplitude that comes as soon as the sound occurs.
The release determines how quickly the effect ends. In a gate, a shorter release time would help clean up the noise in an audio signal, but may cause chattering in percussive instruments, while a longer release time could eliminate the chattering. In a compressor, a shorter release time can produce a choppy sound, especially with low-frequency instruments, while too long of a release time can result in an extremely compressed sound.
To summarize: a dynamic processor changes the dynamic range of an audio signal by changing the amplitude over time.
The threshold is the level at which the processor starts working.
The ratio is the amount the audio signal is affected by dynamic processor.
The attack determines how quickly the effect starts and the release determines how quickly the effect ends.