Energy and Flow

Energy and Flow

Energy is behind every sound, it is the cause of soundwave vibrations and all sounds must follow the natural laws of energy.

Being aware of energy patterns and flow can help us to create gestures and sounds which listeners find natural and realistic.


Energy drives the universe, and understanding the way in which energy works can provide many points of inspiration for composers.

The main rules are:

  • The amount of energy in the universe is always the same. No energy is ever lost or gained, only transferred.
  • No transfer of energy is 100% efficient and some energy will be transferred in unwanted ways.
  • There are six main types of energy:
    • Electrical
    • Thermal/Heat
    • Light/Radient
    • Chemical
    • Elastic potential
    • Kinetic and vibrational (including sound).

Each of these forms of energy act in different ways, sometimes storing it up (such as chemical and elastic potential) and sometimes transferring it (such as electrical, thermal, radiant and kinetic).

Energy in = Sound out

If sounds are to begin (or continue), they need energy input. Think, for example, of traditional instruments which will only create sound if they are being bowed, blown, scraped, plucked or hit. All of these actions transfer energy from the performer into the instrument.

The amount of energy that is put in, will directly affect the properties of the sound out, most noticeably in terms of loudness (but also in terms of sound quality). If less energy (or none) is put in, then the sound will begin to fade away (to drop in loudness).


Sounding objects won’t continue to vibrate forever because resistance, in the air and the solid of the object itself, will slowly drain energy away from the back and forth motion of the vibrations.

For example:

In this example, a significant amount of energy is input at the start [guitar string is plucked]. But, following this initial action, there is no further energy input and so the sound gradually decays, dropping in volume and losing the energy in the higher portion of the energy spectrum (see the disappearance of the yellow lines, representing partials).

Energy Flow

Every sounding object has its own unique flow of energy that relates to the way in which it vibrates. The energy flow of a sound over time is described by its envelope (see also: ADSR).

BUT, it is possible for us to apply new envelopes to existing sounds. For example, we can apply changes in loudness over time using automation, in order to give a continuous sound a changing energy profile.

In this example, a steady square wave tone has been manipulated with automation, changing the ‘gain’ levels. This automation has applied a new envelope, similar to the envelope of the recorded guitar sound above.

See below for more detail:

Of course, this automation only reflects the change in loudness over time. While the sound quality of the guitar sound also changes. By adding in a Low-Pass Filter with its own automation, we can replicate the changes in sound quality over time by gradually eliminating the higher components of the sound.

Not only does the overall loudness change, but the spectrum of the sound also diminishes.

In this way, we are more accurately modelling the natural energy profile of the guitar sound, with smaller and higher frequency waves decaying more rapidly than lower, fundamental frequencies.

Flowing Gestures

Using computers to work with sound provides us with almost unlimited potential in transformation and manipulation. But, being digital, computers favour straight lines and all (1) or nothing (0) situations. Natural energy flows are smoother due to the laws of energy and the physical processes of energy transfer.

  • The amount of energy in the universe is always the same. No energy is ever lost or gained, only transferred.
  • No transfer of energy is 100% efficient and some energy will be transferred in unwanted ways.

This means that it is impossible for new energy to suddenly appear from nowhere. And, if energy transfer was plotted on a graph, it would not be a straight line.

Because these natural energy trajectories surround us, we are all subconsciously familiar with them. This means that when we hear a sound energy that suddenly appears, or one that fails to dissipate naturally, we instantly recognise it as fake because it is disobeying the fundamental laws of energy.

Smoothing out automation lines and ensuring that there are no sudden gains or losses in energy will enable your gestures to sound more natural and familiar to audiences.

New Gestures and Anacrusis

By following the laws of energy transfer, we can create new gestures which cannot happen in the real world, but which can sit naturally in a composition. One of the simplest and most effective gestures is to reverse a sound which originally decays. This creates a crescendo (moving from quiet to loud), which sounds according to the laws of energy and is regarded as musical.


When these crescendoing events are placed before ‘key sounds’, they form an anacrusis. A highly effective musical gesture which launches the listener forwards into the ‘key sound’.

The energy of the gradual build up is concentrated into the ‘ker-ding’ of the bell, making it sound much more impressive than it would on its own.

Using Knowledge of Energy Flow in Composition

We can draw any pattern we like in the automation and apply that as an envelope to sounds. But by examining the way in which natural sounds function, we can learn to create new and synthesised/manipulated sounds that share some natural characteristics, which audiences can therefore unde


Use energy as an inspiration to create a short piece. Explore ideas of energy and remember that energy is neither lost nor gained, but transferred.

Music often creates an emotional flow of energy with areas of high and low tension, which draw the listener along.