ADSR Fundamentals In Music : Everything You Need To Know

ADSR is an abbreviation for Attack, Decay, Sustain and Release. ADSR is the fundamental concept of sound design and synthesis that every music producer and sound designer must understand and implement to create interesting sounds.

In this article, you will learn everything about the ADSR of sound. I will also share with you examples of how you can use ADSR to design and manipulate sounds for your music, film or game sounds. Before we understand ADSR, let us first understand what is a sound envelope.

What is a Sound Envelope?

In sound and music, a sound envelope describes how a sound changes over time with other elements like amplitude, frequencies or pitch. The envelope of a sound wave helps establish the sound’s uniqueness. Sound Envelope has a significant influence on how listeners interpret sound.

All sounds have an envelope, whether they are synthesised by humans or found in the universe. But it is most easy to understand sound envelopes with synthesised sounds.

Envelope generators(AKA transient shapers) are common features of synthesisers, samplers, and other electronic musical instruments. Envelope Generators allow users to control the different stages of a sound. Envelop Generators are circuits that, when triggered, produce a contoured signal over time. Envelope Generators are also called Transient or Contour Generators.

Envelopes can be concerning sound amplitude or frequencies, but mostly they are used with the amplitude of the sound. The sound envelope defines the trajectory and modulation of a sound, while the envelope generator controls the behaviour of the envelope.

What is ADSR?

In music production and sound design, sounds are designed and altered by modulating their envelopes. The modulation of the envelope is done by altering the parameters of an envelope generator. There are four parameters to control and alter a sound envelope — Attack, Decay, Sustain and Release(ADSR).

• Attack: The time it takes for the sound signal to rise from an amplitude of 0 to its maximum amplitude. Attack is a time and amplitude-based parameter.

• Decay: The time it takes for the signal to fall from its maximum amplitude to the desired/designated sustain level. Decay is a time and amplitude-based parameter.

• Sustain: The steady amplitude level produced when a key is held down. The signal remains at this level until the key is released. Sustain is an amplitude-based parameter.

• Release: The time it takes for the sound to decay from the sustain level to an amplitude of 0 when the key is released. Release is a time and amplitude-based parameter.

ADSR envelopes are used most commonly to synthesise sounds using VST synthesisers, hardware synths and samplers. ADSR parameters are used in conjunction with an envelope generator of hardware synthesisers or software plugins to control and alter signals.

These are four different settings that let you change and alter the sound by altering/modulating the sound envelope. The relative duration and the amplitudes of the four phases have a significant impact on how the synthesised tone will sound.

Even though, ADSR envelopes are used most commonly to synthesise and design sounds, every sound you hear has an ADSR envelope. Whether it is a dog barking on a street, waves crashing in the ocean, a guitarist playing a solo, a piano note, someone shouting out loud or the sound of breaking rocks.

Any sound, you have heard, follows the fundamental principle of ADSR. If you start analyzing all sounds in terms of ADSR, sound design becomes fun and addictive. As there is no key press in nature sounds, the Release factor can be ignored.

Attack

The attack phase begins the moment a key is pressed, or a note is played. This phase determines how quickly a sound reaches maximum amplitude before entering the decay phase. Percussive sounds like Kicks, Snares have a short and fast attack. String sounds like violin has a slow attack. A sound with a short attack will be heard immediately. One with a longer attack will gradually fade in.

Decay

The decay phase determines the length of the drop from the maximum level to the sustain level. A sound with a slow decay will take a while to reach the secondary volume set by the sustain. Percussive sounds like Kicks, Snares have zero to very short decay. String sounds like violin has a slow and longer decay time.

Sustain

The sustain phase does not specify a length of time. Instead, it determines the volume or amplitude of a sound for the entire hold time between the decay and release phases.  Sustain is how quiet the sound is after the attack and decay. If a sound stays the same volume for a while, it’ll have a high sustain.

Kicks have zero or a very low sustain level. Toms and other percussive sounds  have a low sustain. Pad sounds and ambient sounds have a prominent and higher sustain level.

Release

Release is the final phase of the sound. Release determines the speed at which a sound ends from the moment you release the key or a note. A sound with a long release will take a long time to fade out.

Depending on the desired sound, the release time can be short or long. Release is generally used in synthesised sounds only.

How To Use ADSR In Music and Sound Design?

Just by altering the ADSR parameters, one can create and alter sounds to a great extent. If you understand and analyse sounds in terms of ADSR, you can easily create sounds using synthesisers. As one of the fundamentals of sound design, ADSR is pretty important! ADSR is the secret ingredient to making synths that sound incredible.

One can create Percussion, Pads, Synth sounds and a lot more by using small tweaks in these parameters. Let us look at how altering the ADSR parameters envelop alters the sound.

ADSR parameters for the most common sound types used in Electronic Music Production

Sound Type	Attack	Decay	Sustain	Release
Kicks	Fast	Short	Nearly Zero	Very Short
Percussive Sounds	Fast	Short	Low	Very Short
Pads	Slow	Short-Medium	Medium	Short
Strings	Slow	Short-Medium	Low-Medium	Short-Medium

Use Of ADSR In Mixing

ADSR can also be used to clean up sounds and mixes. Using a transient shaper, one can easily make desired changes to clean up mixes.

ADSR Envelope helps to alter the length of sounds. This can be applied to mixes, especially if you are having trouble with getting some sound to sit properly in the mix. Here are a few tricks that you can use with a transient shaper and apply to your mixes: - 

1. Making Sounds Sit In The Mix:—With a transient shaper, altering just attack and sustain can help you make your mixes sound a lot better. If you  are having a hard time getting instruments like guitars or piano to sit properly in the mix, try throwing in a transient shaper to the signal chain. Alter attack and sustain settings. Attack sharpens or dulls the initial transient. Increasing attack makes it punchier, decreasing attack softens it. Decreasing the attack also makes the sound feel pushed back in the mix. Sustain affects the tail end of the sound, shaping the later transients.  Decreasing the sustain shortens the sounds, making it tighter. Increasing the sustain brings up the natural reverb, making it sound roomier.
2. Adding Punch:—If you need your kick to cut through the mix without getting loud. Try adding a transient shaper and increase the attack. This will help the kick sound punchier without getting clipped.
3. Clean Up Noise: – Buzz from your guitar amp or unwanted room ambience can easily be fixed with a transient shaper. Try turning down the sustain.
4. Make Vocals More Present and up Front:—Playing with a little automation and attack of a transient shaper, one can easily make vocals sound more upfront and cut through the mix.

Why Understanding ADSR Is Important For Musicians and Sound Designers?

All beginners rely heavily on sound samples. When you make music using just samples, you are relying on luck and others to get better at producing music. You might find good samples, or you might have a difficult time.

Understanding sound design will help you make your own sound that you can use in your music and projects like a pro. It will not only make your music sound unique, but your sound pallet will be a lot more refined and better sounding.

If you start analysing sounds in terms of ADSR and implement the same while designing sounds, you will have a great time designing sounds in the studio. Knowing what, how and when to use ADSR fundamentals—is essential for music producers and sound designers.

Hope this article helped you understand one of the most fundamental concepts of sound design, and you will implement it in your work. If you have any feedback, comment or queries, please do post them in the comments below.

In the next lesson, learn how to design a kick sound from scratch.