What is modulation in music production? Learn how the different modulation effects and techniques can make your music more interesting.
What is Modulation in Music Production?
In music production, modulation means changing the property of sound over time. The modulation of sound requires a source signal called a modulator that controls another signal called a carrier. Modulating sounds adds a sense of motion, dimension, and depth.
There are several ways to process audio with modulation. You can modulate sound with various effects and synthesis techniques. This guide explains the different ways to manipulate sound using modulation.
What is a Modulator?
Modulators produce a source signal that manipulates the settings of a target signal called a carrier. Also, modulators do not make a sound. They change the sound by controlling parameters on effects and instruments that affect the source signal. For example, you can route a modulation source to modulate pitch, volume, pan, filter cutoff, wavetable index, and effects controls. You can modulate nearly every parameter on plugin effects and instruments!
Common modulator types include LFOs, ADSR envelopes, mod wheels, and step sequencers. They are often seen on synthesizers, drum machines, samplers, controllers, and various effects.
A Low Frequency Oscillator (LFO) is an integral part of modulation. An LFO is a modulation source that produces a repeating signal that controls a destination source.
Moreover, waveform shapes determine the behavior of an LFOs repeating signal. For example, most LFOs have a selection of waveform shapes that control how the signal will rise and fall. They also have controls to change the amplitude (depth) and speed (frequency rate) of the signal.
Common LFO modulation targets are the filter frequency cutoff or volume control. For example, create bass wobbles by either modulating the volume or filter cutoff.
ADSR Envelope Modulation
ADSR means Attack, Decay, Sustain, and Release. Use these four envelopes to shape the timbre of a sound or to modulate other parameters. Also, modulation envelopes do not create a continuous signal like an LFO. Instead, they can be triggered by a note, sidechain input, or user input like a key press.
A common modulation target for an envelope is the filter frequency cutoff. For example, modulating the filter to open the cutoff every time a note plays.
A mod wheel is an expression control on a synthesizer or keyboard. It’s commonly used to apply pitch-bending or vibrato. MIDI controllers offer a similar feature called aftertouch. Aftertouch is a pressure sensitive touch strip that can modulate various parameters.
Step Sequencer Modulation
Step sequencers are programmable modules that generate note patterns. A step sequencer can also modulate various parameters on a synthesizer.
Using a step sequencer as a modulation source gives you the ability to create simple or complex rhythmic patterns. Modulating sound with a step sequencer also gives you more control because of the ways you can edit the individual steps.
Common step sequencer modulation targets are the filter frequency cutoff or volume control. For example, every step will open or close the filter cutoff at different amounts.
Common modulation effects include chorus, flanger, phaser, tremolo, vibrato, auto-pan, and LFO. These creative audio effects add movement, depth, width, and character to sounds. Moreover, these effects are mostly used in sound design rather than for practical mixing techniques.
Chorus effects add richness, thickness, stereo width, and a lush, shimmering quality to your sound. The effect duplicates the incoming signal and then mixes it with one or more copies that are pitch-shifted and delayed. An LFO modulates the delay and pitch between the signals. While depth and rate controls make the effect more or less intense.
Flangers are similar to chorus effects. Flanging also mixes the source signal with a slightly delayed copy modulated by an LFO. The difference is a shorter delay between the identical copies. Also, flangers can feed the duplicated signal back into the original signal to further exaggerate the effect.
A flanger effect can also generate complex harmonic sounds. The shorter delay produces a “comb filtering” effect caused by phase cancellation. This creates a swirling, underwater texture. Also, increasing the feedback can generate metallic robot-like effects.
Phasers or phase shifters are also similar to chorus and flanging effects. However, the phasing sound is more subtle than the harsher flanging effect. A phaser also splits the signal into two identical copies, modulates one, and mixes them. The difference is phasers shift the waveform phase of the copied signal rather than delaying it.
Moreover, phasers use “all-pass filters” to create a phase shift in the frequency of a sound. An LFO controls the movement of those filters between the phase-shifted signals. Sweeping through the notches and peaks those filters create also causes phase cancellation. The result produces the signature whoosh sound of a phaser.
Tremolo is a modulation effect that rhythmically changes the volume of a signal. An LFO controls the volume depth and rate. Most tremolo effects also have selectable waveform shapes that control how the volume rises and falls.
Tremolo is useful for creating gentle or intense stuttering and pulsating effects. Create tremolo effects using dedicated tremolo effects or by modulating a volume control with an LFO.
Vibrato is a modulation effect that changes the pitch of a signal. An LFO controls the pitching depth and rate. Most vibrato effects also have selectable waveform shapes that control how the pitch rises and falls.
Applying subtle amounts of pitch bend to notes or the incoming signal can make a sound more interesting. It creates a sense of movement and rhythm. Vibrato can also help sounds stand out in the mix.
An auto-pan effect rhythmically changes the panning position of a signal. An LFO controls the panning stereo width and rate for the left and right stereo channels. Most auto-pan effects also have selectable waveform shapes that control panning behavior.
Auto-pan effects can also manipulate the amplitude of a signal. For example, you can create automatic panning, tremolo effects, and beat-synchronized chopping effects. Check out our creative Ableton Live Auto Pan tips below!
Some synthesis techniques use modulation to create sound. Common techniques include Amplitude Modulation, Frequency Modulation, and Ring Modulation.
Amplitude Modulation (AM)
Amplitude modulation or AM synthesis utilizes one oscillator to modulate the volume of another oscillator. It’s a form of tremolo. AM is also one of the earliest forms of synthesis.
Frequency Modulation (FM)
Frequency Modulation or FM Synthesis is a versatile synthesis technique. FM synthesis is used to create complex and harmonically rich textures.
FM synthesis creates complex waveforms by using the waveform frequency of one or more oscillators to modulate the frequency of another oscillator. It’s like an extreme form of vibrato. Also, the oscillators used in FM synthesis are known as “operators.” Operators can function as a modulator or a carrier.
Modulation is a great way to make your music more interesting. We encourage you to experiment with the various modulation effects. Try subtle and extreme settings to manipulate audio in unique ways. However, modulate sounds with caution. Excessive use can ruin your mix.