Ring Modulation

Starting today, I plan on focusing on the fundamental techniques of sound design. I won’t go too deep into the theory, as much of this information is described better elsewhere. My intent is to provide just enough of the basics so that you can start experimenting immediately, and hopefully start to recognize some of these synthesis design patterns as you study other instruments in the future. We begin with Ring Modulation.

The Computer Music Tutorial by Curtis Roads describes ring modulation as “simply the multiplication of two bipolar audio signals by one another.” Often times, one of the signals is a sine wave, though certainly not always. This technique is a quick and easy way for introducing inharmonic frequencies to a sound, and is quite popular in science fiction, as it is used in everything from 1950s era spaceships to robot voices. I’m personally fond of Daleks and Cybermen.

I created a simple example that ring modulates two sine wave oscillators together. The first oscillator has a constant frequency of 440Hz, while the second oscillator starts with a value of 1Hz, and doubles once a second until it plays the 2048Hz tone.

Download today’s example here.

Synthesis Fall 2010

One thought on “Ring Modulation

  1. This is one of the more interesting examples. Can you show us how to have the modulation increase linearly with a for loop instead of stepwise?