Much like the envelope, the low frequency oscillator (LFO) is a synthesis fundamental utilized for changing sound parameters over time. A LFO is basically the same thing as an audio oscillator, with the biggest difference is that they’re designed to run at a much smaller frequency range. The range is generally below the limits of human hearing, 0Hz to 20Hz. Though many analog and digital LFOs usually oscillate at higher frequencies. There are generally no restrictions for using an audio oscillator as an LFO.
Today’s example uses an LFO to modulate the frequency of a square wave oscillator. I use three different waveforms (triangle, sawtooth, square) so that you can hear how their shapes affect the sound. For example, at the lower frequencies, the triangle wave causes the pitch of the audio to smoothly go up and down while the square produces a trill-like quality.
In the listening example, you’ll hear everything from vibrato, to trills, to classic sci-fi lasers to something straight out of Pac-Man.
Download low_frequency_oscillator.csd here.