Overview
An envelope controls how a sound changes over time.
In synthesis and audio production, envelopes are used to shape:
- volume
- filter behaviour
- pitch
- other parameters
The most common type is the ADSR envelope, which describes how a sound starts, evolves, and ends.
What is ADSR?
ADSR stands for:
- Attack
- Decay
- Sustain
- Release
These four stages define how a sound behaves from the moment it is triggered to when it stops.
The ADSR Envelope Shape
An ADSR envelope is usually shown as a graph:
- horizontal axis = time
- vertical axis = level (often amplitude)
Attack
What it does
Attack controls how quickly the sound reaches its maximum level after being triggered.
How it sounds
- Fast attack (0–10 ms)
Immediate, sharp start
Useful for drums and percussive sounds - Slow attack (100 ms+)
Gradual fade-in
Useful for pads and ambient textures
Decay
What it does
Decay controls how quickly the sound drops from its peak level down to the sustain level.
How it sounds
- Short decay
Quick drop after the initial hit - Long decay
More gradual transition
Sustain
What it does
Sustain is the level the sound holds while a note is being held.
Unlike the other stages, sustain is not a time value — it is a level.
How it sounds
- High sustain
Sound remains strong while held - Low sustain
Sound fades after the initial hit
Release
What it does
Release controls how long the sound takes to fade out after the note is released.
How it sounds
- Short release
Sound stops quickly - Long release
Sound fades out gradually
Putting ADSR Together
These four stages combine to define the character of a sound.
Use the controls below to adjust attack, decay, sustain and release, then trigger a note to hear how the shape of the envelope affects the sound.
Try setting a fast attack and short release for a pluck-like sound, then increase the attack and release for something softer and more pad-like. Try and create a piano style shape after that.
The ADSR envelope shapes how a sound changes over time, but the source waveform also affects what you hear. Use the waveform selector to compare the same envelope applied to different oscillator shapes.
Try keeping the envelope the same and switching between sine, square, sawtooth and triangle. The shape of the envelope does not change, but the character of the sound does.
Example 1: Pluck
- Fast attack
- Short decay
- Low sustain
- Short release
👉 Result: a short, percussive sound
Example 2: Pad
- Slow attack
- Long decay
- High sustain
- Long release
👉 Result: a smooth, evolving sound
Example 3: Piano-style
- Fast attack
- Medium decay
- Low sustain
- Medium release
👉 Result: strong initial hit, then natural fade
Envelopes and Amplitude
The most common use of an envelope is to control amplitude (volume).
This is often called an:
👉 Amp Envelope
It determines how loud a sound is over time.
Envelopes and Filters
Envelopes can also control filters.
👉 Filter Envelope
This changes the cutoff over time.
Example
- Fast attack → bright initial sound
- Decay → filter closes slightly
- Sustain → darker tone held
This is common in:
- bass sounds
- plucks
- classic synth patches
Why Envelopes Matter
Without an envelope:
👉 a sound would just turn on and off instantly
With an envelope:
👉 the sound becomes expressive and shaped
Common Mistakes
- Using only default envelope settings
- Ignoring release time (causes abrupt endings)
- Not matching envelope to the type of sound
Releated Links
- Filters (Low-pass, High-pass, Band-pass)
- Oscillators (Sine, Saw, Square, Noise)
- Frequency, Amplitude and Waveforms
- Signal Flow Explained
- What is a Synthesizer?
This article is part of the Music Production Reference Library, organised into volumes covering sound, theory, production, and release.
