Frequency Modulation

Frequency Modulation (FM) is the technique that defined the sound of the 80s. FM lets you create a whole class of sounds with just two sine waves as input. In this example, we modulate the frequency of a 300 Hz sine wave signal with a new 1 Hz ‘carrier’ sine wave with an amplitude of 200.

FM synthesis for sound was introduced by John Chowning in 1973. Soon after, it was licensed to Yamaha, which lead to the first wildly popular digital synthesizer, and defined that classic synth sound of the 80s.

What happens if you turn down the modulation index, and increase the modulation frequency so that it’s in the audio frequency range? You’ve just entered the strange world of FM synthesis!

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