Final answer:
An envelope is used to give a synth sound its "shape" by controlling the attack, decay, sustain, and release parameters.
Step-by-step explanation:
An envelope is used to give a synth sound its "shape". The envelope refers to the way a sound evolves over time, including its attack, decay, sustain, and release. By adjusting these parameters, the shape of the sound can be manipulated, resulting in different textures and characteristics.
For example, a synth sound with a fast attack and quick decay may have a sharp and percussive shape, while a sound with a slow attack and long sustain could have a smooth and sustained shape.
The envelope is typically controlled using an ADSR (Attack, Decay, Sustain, Release) envelope generator, which allows musicians and producers to shape the sound to fit their artistic vision.