Audio Processes

20 Modulation for Synthesis

20.1	Introduction
20.2	Amplitude Modulation
20.2.1	Basic Principles
20.2.2	Practical Examples
20.3	Frequency Modulation
20.3.1	Basic Principles
20.3.2	Parallel FM
20.3.3	Multiple Modulator FM Arrangements
20.4	Further Modulation Methods
20.5	Developing Processes and Learning More

20.1 Introduction

Modulation is the process of varying one part of a signal, using another signal, over a length of time. The focus in Chapter 9 was on periodic variation of modifier parameters at low modulation rates. In this chapter, there are two significant extensions to the ideas seen previously:

• Using modulation to create new sounds, as well as to modify those that already exist.
• Using modulation of parameters at rates above 20Hz.

Synthesis techniques ...