If you are composing electronic music, whether it is dub-step, dance, or something monumental as cinematographic electronic music, you still need to know how the audio wave works to make your craftsmanship better. Attack, decay, sustain and release influence the audio wave and change the way you can use it artistically. Prepare to dive in with us to know more about the attack, decay, sustain and release in music production.
Scientific background
Sound waves, which are produced by speakers, headphones or any object around you, are perceived by our human auditory hearing. A sound wave first travels through the outer ear and then to the brain’s temporal lobe, where it gets converted to the audio information that we hear. The fact that the outer ear has in itself two ears, you can for sure know where the signal came from and from which side.
In addition to knowing the originating location of the sound, we also have the ability to recognize the timbre and register how the sound changes over time. And on those, our natural capabilities are based on producing sounds artificially, whether it would be a musical piece or media broadcast. Nowadays, we can produce sounds either using analog means, or we can do it digitally.
Analog sound reproduction is made by changing the voltage on the different electrical circuits of the device that is used to reproduce sound. Since there is no way of translating digital sounds into actual mechanical sound waves, all of our sound reproducing equipment is analog. That said, how we actually produce sounds have changed dramatically over time.
With a marginally low amount of exceptions, almost all of the sounds we use are made using digital means. Especially when it comes to modern audio production. Digital sound is made mathematically using various binary digits combinations and involves some sort of computing power. And since we basically manipulate numbers to change the sound wave’s character and behavior, it gives us a lot of flexibility and precision.
Back in the old days, attack, sustain, decay and release functions were controlled by special additions to the circuitry, which were called envelope generators. They were first introduced by the famous American engineer Robert Moog in the 60’s. He used a doorbell button and the capacitor wired to the synthesizer to control voltage. Later, this simple circuitry evolved into an envelope module that implements modern ADSR controls and, with some modernization, is used to these days in the analog synthesizers.
Since we no longer rely on analog circuitry to make synthetic sounds, modern digital technology gives us a lot of flexibility in terms of ADSR controls. Today, almost every digital synthesizer has those controls because it is a matter of fairly simple programming. Even more so, using dedicated audio plugins, we can control ADSR not only of synthetic sound waves, but also of audio samples and live recordings.
Attack
Attack in an envelope control that manipulates the time it takes to reach its peak from 0 of a sound sample. Basically, using the attack control and, depending on the settings, you can tell your synthesizer to gradually increase the amplitude of the sound from complete silence when you press the key. Also, this applies on any audio sample, whether it be a simple clap or a complex piano part. When attack control is disengaged, your sound will start as soon as you press the button or start to play an audio sample. Slow attack times are usually used to create cinematic sweeps or soft transitions.
Decay
Decay represents the time it takes to go from the initial attack to the SAT sustain level. It means that, using this parameter, you can either go to the sustain level right away or create some sort of drop. Some synthesizers also have the holt parameter that sets how long the sound stays at full amplitude before it enters the decay. You can set the decay to never reach the sustain phase, which is good for short pluck sounds and various percussive sounds.
Sustain
Sustain controls the level of the sound which is held until the key is released. Turning the sustain off will let you achieve mentioned above pluck and percussive sounds. Putting the sustain at its peak setting will let you make infinite sustain pads. Going further, the sustain parameter can also be modulated in order to create evolving non-linear sound textures.
Release
Release parameter controls the time it takes the initial amplitude of the sound to decay from the sustain level after the key is being released. Setting release to zero will make the sound stop exactly when you release the key. Setting release to maximum gives you the most prolonged decay and is dependent on the specific software you are using. Some plugins lets you have an infinite release, which means that sound will sustain indefinitely after you release the key.
How to use ADSR in sound synthesis
The most prominent usage of envelope controls is obviously the synthesis. Almost every modern digital synthesizer has ADSR controls, some even let you control not only the sound wave but the actual filters and effects. For example, you can use separate ADSR for modulation effects, which means that you can make it start gradually from zero, decay over time, and then start again regardless of the ADSR settings you were using on the initial soundwave.
More traditionally, using ADSR settings lets you shape your synthetic sound in any imaginable way you like it to sound. You can create short and aggressive plucks using short attack time settings, zero release, and implementing absolutely no sustain.
Or you can literally make a sweeping wave by setting a very long attack, some sustain, and an extended release. As it was mentioned before, some software will give you an option to modulate each of those four controls separately, which is great for creating unusual and experimental movements in your production. For example, your attack does not have to be a smooth, gradual curve. You can make it go from zero to a certain level, then drop to another level, and then finally it can reach the sustain phase, which in turn could be modulated to have some movement from left to right or have non-linear amplitude entirely.
The same principle can be applied to the release and decay settings. You can easily create some bouncy and sweeping effects after you release the key.
How to use ASDR in audio production
Since, as we discovered earlier, we are dealing with purely digital sound and all actuality, your CPU does not discriminate between synthetic sound waves and audio recordings. Since to the CPU, those are all just binary digits, it means that they can be treated equally, and we can apply the same envelope controls to the audio recordings that we usually do to the synthesizers. This could be achieved using dedicated plugins, which are called transient shapers.
Imagine that you have an ambient project that simply strives to have some beautiful electric guitar sweeps, and you were unfortunate enough not to have a volume pedal at your disposal. Well then, you can simply apply a transient shaper, set the longest attack possible, and let the sustain ring out naturally. Or if were dealing with an overcompressed piano part that tends to have unnatural and unpleasant popping sounds, that also can be fixed by a transient shaper using slower attack times.
If you are bold enough, you can even use a transient shaper on a master bus in conjunction with or even instead of a compressor. This opens up a lot of possibilities because you can emphasize the attack and thus making the sound “bitier”, or you can smooth out inconsistent attacks. Turning the sustain setting of a transient shaper on the master bus will make your mix sound richer and fuller. The same principle goes not just to a master bus but to any separate element of your mix.
