Synthesizer Library Podcast

Amplitude Modulation Defined Amplitude modulation is the process of changing the volume of one wave according to the pattern of another wave (Volume is used here as a simple way to understand amplitude. The two are not exactly the same in practice.) Changing the volume of a sound results in a tremolo effect when that change happens relatively slowly. When we speed up that change, we no longer perceive a simple change in volume. That periodic change itself becomes an audible pitch. In fact, when two simple sine waves are combined in this way, two audible pitches appear. These pitches are called “sidebands” and their frequencies turn out to be equal to the sum and difference of the two original waves. For example, a sine wave ad 150 Hz modulating another sine wave at 100 Hz produces a sideband at 250 Hz (150 + 100) and another sideband at 50 Hz (150 -100). That’s great, but what does it mean for synthesizing sounds? In the podcast we play a few samples so you can hear the effect. You’ll