“A fundamental concept of Ambient music is the need to listen closely to sounds that are a familiar part of daily life, but which rarely if ever are given the attention they deserve.” (Peter Manning, Electronic and Computer Music, 2004, p177)
Morning Reverb (36 x 48 inches) (2013) Edition of 6 © Dave Tilton
The reverberation of sound led me to consider how time of day resonates in a landscape. Morning Reverb reflects the lingering aspects of a sunrise despite the fleeting nature of the event.
A while back I was doing some reading about ADSR envelopes. An ADSR envelope is used in electronic music synthesis to control the Attack, Decay, Sustain and Release parameters of a sound (more about this later). ADSR envelopes serve as a model for some of the techniques I developed to create textures for my art.
It was early morning. I was sitting on my porch, having a cup of coffee and the sun was starting to rise. I put down my reading to watch and it occurred to me that the event we refer to as sunrise actually has a number of components. There is the time when the sun’s rays just begin to take the dark out of night and color a spot on the horizon. As the sun emerges it becomes the focus until it reaches full circle and breaks free of the horizon. Then the focus shifts to the light that floods land and sky with color and shadow. Eventually, the color begins to shift and shadows fade as remnant reds transition to the full light of day. As I thought about this component structure, I realized it shares a great deal of similarity with the structure of sound.
Envelopes are used in synthesis as temporal constructs to give shape to a sound. Virtually all sound can be characterized by how its loudness and spectral content change over time. A tap on a snare drum will have a sharp, loud attack with a short sustain, decay and release. A note played on a violin will have a more gradual attack and a longer sustain, decay and release.
ADSR envelopes are generally controlled by envelope generators. Synthesists use these generators to shape a dynamic-amplitude (volume) contour for a sound by adjusting individual parameters of the envelope. An ADSR envelope is a four-stage envelope that is specified by four parameters:
Illustration of an ADSR Envelope
Attack time is the length of time from 0 decibels to maximum volume starting when a trigger such as a key press is activated.
Decay time is the length of time from the maximum volume to the volume established for the sustain level.
Sustain level is the volume maintained until the key is released.
Release time is the amount of time it will take for the volume to decay to 0 decibels from the sustain level after the key is released.
This last stage, Release Time, is a complex stage in which the sound fades and blends with other sounds in the composition. It is also a stage during which a synthesist can add certain acoustic qualities that will give synthesized sound a real-world presence. Two methods used to add these acoustic qualities are reverberation and resonance.
Reverberation is the persistence of sound in a particular place after the original sound is produced. A sound made in an enclosed space causes multiple echoes to build up and then slowly decay as the sound is absorbed by things like walls and air.
Resonance is the prolongation or amplification of a sound by feeding back a narrow band of frequencies at or near the frequency at which something tends to vibrate once the source that caused the vibration is removed. For example, a plucked string is barely audible, but if you add a resonating device such as the hollow body of a violin or the body of a grand piano, the sound is much louder, fuller and complex.
Pondering the Release Time stage of ADSR envelopes and how time of day resonates in a landscape got me thinking about how I might use reverberation and resonance as concepts to express the lingering aspects of an event like a sunrise. This was the inspiration and (challenge) for Morning Reverb.
Since reverberation and resonance are sound behaviors that occur due to the interaction of sound waves with real-world environments, I wanted the overall composition to embody a sense of realism. I also needed Morning Reverb to incorporate the subtlety and complexity of the Release Time stage so that the resonance and reverb would show through.
I divided the textures I would create for the image into two basic categories: background and foreground. I wanted the background textures to create a lush backdrop and to set the overall tone for the image. They needed to carry the full range of a subtle, sumptuous color palette while at the same time reflect and enhance the color and richness of the foreground textures. The foreground textures would create the structure in which the reverberation and resonance was going to take place. I wanted this structure to suggest a landscape of a slightly grand scale (reverb needs a big room). To help establish this scale, I needed textures that would suggest representational elements such as trees, clouds, land and horizon. These textures also needed to contain areas for the background textures and colors to ‘show through’ in varying levels of spacing and transparency.
I used a type of electronic music sound setting known as a ‘pad’ as a working concept for creating the background textures. Pads are basically long sustained chords or tones with envelopes characterized by very long attacks and releases. Pads are often used in compositions at low levels to supply rich, subtly complex backgrounds to the lead/melody components.
The ‘pads’ I created for Morning Reverb carry the background color palette via a set of textures that run throughout the composition and serve as a backdrop for the foreground textures. The primary purpose of some of the ‘pads’ is to distribute color. Others provide subtle textures that help those colors hook into the spacing and transparency of the foreground textures (i.e. they help bridge the gap between the distributed color palette and the foreground textures).
The foreground textures were created using a number of techniques modeled on concepts used in frequency modulation, additive, subtractive and sample-based synthesis, and envelopes. Some of these techniques are discussed in more detail in my blog about Water Falls I. In all, several dozen textures were combined to create the suggestive representational elements.
It was challenging to come up with a set of techniques that would allow me to incorporate the notions of resonance and reverberation in an image. But, in the end I feel my experiments for creating the background ‘pads’ and the foreground textures worked pretty well – I can hear the lingering aspects of a sunrise in Morning Reverb.
