Computer Music (MUSC 216)
Creating a Simple FM (Frequency Modulation) Bell

The technique of fm synthesis (frequency modulation)) has some advantages over additive synthesis in creating complex harmonic spectra with few operators. Using the technique described in the tutorial, Creating a Simple Bell, you had to use a minimum of 10 operators to program a BELL sound: fundamental frequency (1 operator), 8 separate partials (8 operators) and an amplitude envelope (1 operator). Using FM techniques you can achieve approximately the same effect using only 4 operators.

If you have not already done so, please read the tutorials, Additive Synthesis, Creating a Simple Bell, and Fm Synthesis.

Using SYD you will apply FM synthesis techniques to create the effect of the 9 partials of the Additive Synthesis Bell using only 2 operators: the carrier operator and the modulator operator. The sideband frequencies which are produced in the FM patch are the equivalent of the partials in the Additive Synthesis Bell. Here is the SYD patch for a simple FM bell patch

Figure 1: SYD Patch for an FM Bell


The duration of the sound output should be 6 seconds. The duration of the amplitude envelope should mach the duration of the sound output (6 seconds). Here are the settings for the amplitude envelope:

Figure 2: Amplitude Envelope Settings


Figure 3: Carrier Operator Settings
Figure 4: Modulator Operator Settings

Listen to the FM Bell patch: FM Bell (MP3)

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