Introduction to Frequency Modulation Synthesis

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We’ll be using Bitwig Studio’s built in FM-4 Instrument to demonstrate the basic theories and principles behind Frequency Modulation Synthesis. I would actually argue that understanding FM is easier than understanding any other synthesis method we've covered so far. The difficult part is the application of that theory. The premise of FM is simply that when one audible frequency modulates another audible frequency side bands (additional overtones) are produced. Depending on the ratio/relationship of the two frequencies and the depth of modulation the overtones that are produced may be consonant, dissonant, or some blend of both. Envelopes can be used to control the relative depth of modulation therefore a filter is not necessary to take away or add overtones (the envelopes can do that). Typically the rule of thumb is the more perfect the ratio the more consonant the resulting side bands and ultimately sound.