This paper discusses details related to the automatic control of effects parameters. Specifically, it examines control of audio effects when synchronized with a musical piece’s rhythm. Synchronization is achieved by having control data that is periodic with the bar-length. The need for continuity in the control data is also discussed. This concept is introduced in terms of modulation techniques known as ASK and CPFSK. This is expanded upon with a discussion of a curve drawing technique that is common to computer graphics.