15. Generators and Modifiers

In most synthesis systems, the process of synthesizing sound is achieved by connecting synthesis modules that perform different jobs. A particular system may have only a few modules to carry out a limited number of tasks, while another may have a virtually unlimited collection of modules, each carrying out a different function.

To help conceptualize the functions carried out by each module, they are classified into groups. Two of the most fundamental classifications of these synthesis modules are generators and modifiers. A generator module creates the sound material (think of the generator as the originator of the signal). A modifier module changes the sound material it receives. Because of their respective operations, generators precede modifiers in the synthesis of sound.

Generator Modifier Generates Sound Material Modifies Sound Material

Diagram 15-1: Generator outputs signal to modifier which alters the sound.

The generator creates a sound signal, and outputs it. The signal is input to the modifier, which then alters it.

Generator Generator Output Modifier Modifier Output

Example 15-2: The generator creates a sound signal, the first modifier changes it, and the second modifier changes it again.

The generator-modifier system can easily be extended. A modifier may output its altered sound to a second and third modifier, each modifier module producing some added change in the signal.