An ADSR envelope is a control that shapes how a sound changes over the duration of a note, broken into four stages: attack, decay, sustain, and release. If you have seen those four letters on a synth and wondered what they mean, the ADSR envelope is simply a way of telling the synth how a parameter — usually volume or filter — should rise, fall, hold, and fade each time you play a note.
Envelopes are one of the most important tools in sound design. Once you understand the four stages, you can make a sound punchy, smooth, plucky, or slowly evolving.
What the ADSR envelope stages do
Each letter controls one stage of the note’s life:
- Attack — how long the sound takes to reach full level after you press the key. A short attack is instant and punchy; a long attack fades in slowly, like a pad.
- Decay — how long it takes to drop from the peak down to the sustain level.
- Sustain — the level the sound holds at while you keep the key pressed. Note that sustain is a level, not a time.
- Release — how long the sound takes to fade to silence after you let go of the key.
How the stages work together
Picture pressing and holding a key. The sound rises over the attack time, falls over the decay time to the sustain level, holds there as long as you hold the key, then fades out over the release time once you let go. Adjusting these four controls is how you turn the same oscillator into completely different instruments. The ADSR envelope is a core part of synthesis — see our explainer on what a synthesizer is for the full picture.
Envelopes on volume vs filter
Envelopes do not only control volume. In subtractive synthesis, a second envelope often controls the filter cutoff, so the sound’s brightness evolves over time independently of its loudness. A fast filter envelope creates the bright “snap” at the start of a pluck, while a slow one makes a sound bloom open. Our guide on subtractive synthesis shows the filter and envelope working together in a real patch.
Practical envelope examples
- Plucky synth: instant attack, short decay, low sustain, short release.
- Pad: slow attack, slow release, high sustain for a smooth swell.
- Stab: fast attack, fast decay, no sustain — a sharp, short hit.
- Organ-like: instant attack, full sustain, instant release — on while held, off when released.
Envelopes beyond synths
The envelope concept appears in other tools too. Some compressors and effects use attack and release controls that shape how the processing responds over time, following the same logic. Understanding ADSR therefore helps you with dynamics processing as well — our EQ and compression fundamentals covers attack and release on a compressor, and the broader mixing and mastering hub builds on those ideas.
Tips for shaping sounds with ADSR
Change one stage at a time and listen. A common beginner mistake is leaving a long release that causes notes to overlap and muddy the sound, or setting too slow an attack that makes a part feel late against the beat. Match the envelope to the role of the part: rhythmic parts usually want quick attacks and short releases, while atmospheric parts want slow, gentle shapes. To play and audition these shapes, you will want a controller — see what a MIDI controller is.
Frequently asked questions
Is sustain a level or a time?
Sustain is a level, not a time. It sets how loud (or how open the filter is) the sound holds at while you keep the key pressed. The other three stages — attack, decay, and release — are times.
What does ADSR stand for?
ADSR stands for attack, decay, sustain, and release — the four stages of the most common type of synth envelope, which together shape how a sound changes over the life of a note.
Can an envelope control more than volume?
Yes. Envelopes commonly control filter cutoff so a sound’s brightness evolves over time, and they can modulate pitch, effects, and other parameters depending on the synth.
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