Modulation effects change or move parts of a sound over time to make it more interesting or colorful. Modulation effects are often used to add a sense of motion or texture, or to make a sound stand out or blend in, and there are a variety of choices that use different techniques to create their unique vibe.
Examples
As mentioned above, there are many types of modulation. A few are demonstrated below.
Dry guitar recording:
The guitar with a chorus effect, which uses imperceptibly short delay and pitch shifting to modulate a sound:
The guitar with a flanger effect, which imitates an old reel-to-reel tape trick of slowing down the tape reels with your thumb while recording:
The guitar with a phaser effect, which sounds similar to flanger, but doubles the audio signal and puts it out of phase with the original:
The guitar with a rotary-cabinet (Leslie) simulator. This imitates the effect of a speaker on a rotating motor, so it faces toward and away from the audience and creates a doppler effect for the listener. Use on a lot of classic rock organ sounds, and a nice way to create subtle variation or movement.
The guitar with a ring-modulator effect. Ring modulators perform tricks with the overtone frequencies and can create very dramatic modulations, sometimes sounding nothing like the original sound.
The guitar with a tremolo effect. Tremolo modulates the volume of a signal and is often confused with or mislabled as vibrato, which makes slight modulations of pitch.
