Amplitude Modulation Synthesis is a type of sound synthesis
where the gain of one signal is controlled, or modulated, by the
gain of another signal. The signal whose gain is being modulated
is called the "carrier", and the signal responsible for the
modulation is called the "modulator". In classical Amplitude
Modulation, or AM Synthesis, both the modulator and the carrier
are oscillators. However, the carrier can also be another kind
of signal, such as an instrument or vocal input. Amplitude
Modulation using a very low frequency modulator is known as
Tremolo, and the use of one audio signal to Amplitude Modulate
another audio signal is known as Ring Modulation. Simple AM
Synthesis Classical AM Synthesis is created by using one
oscillator to modulate the gain of another oscillator. Because
we are changing the gain of the carrier oscillator from 0 (no
gain) to 1 (full gain), the modulating oscillator must output a
signal which changes between 0 and 1. This is most often done at
audio frequency rates from 20 Hz