One of the more important synthesis techniques is modulation. Last semester we learned how to use an LFO to change the pitch of an oscillator slowly, creating vibrato. This week, we learn how to build that structure from the ground up using native Max audio objects. The basic modulation scheme can be applied to any parameter, not just oscillator frequency. Any waveform, including band-limited noise (as generated by rand~), can act as a modulation source.
If you raise the frequency of a periodic modulation source, such as a sine wave oscillator, so that it is higher than 20 Hz, you create timbral changes. This technique of modulation synthesis comes in two basic forms: amplitude modulation (AM) and frequency modulation (FM), depending on whether the modulation source (the modulator) controls the amplitude or the frequency of the oscillator we hear (the carrier).
We will try ring modulation (RM), which is a more commonly used special case of amplitude modulation. Then we will explore FM synthesis, which is more complex than either AM or RM.