Database of ideas and sounds
AESTHETIC POTENTIALS OF ECO-STRUCTURALISM
In a compositional system that seeks to preserve natural motion within a music structure, there are certain aesthetic potentials that provide particular value in a musical and compositional context. These include the fact that nature provides a natural rhythm and a natural series of events that may seem very random to the casual observer, however, when compared to true randomness these events are merely irregular. This natural irregularity is something that offers many musical possibilities. When used as a compositional structure it could dictate when certain musical events take place; such as a phrase change, a musical accent, a rest, a change of musical instrument, change in tempo, a new movement, the rhythmic pattern or melodic pattern for a melody or harmony, etc.
Natural irregularity can also be used more directly in sound generation processes to produce and modify tones. One specific method we have been working with is to use the eco-structural data as a waveshaping tool. One of the benefits of this process is that it allows the composer to easily add colour to a simple sine tone in a controlled and repeatable manner. The same data can be applied to any sine wave tone to add the same colour across a whole pitch class. As an example of this process we compare five different generated tones. Each tone began as a sine wave. The eco-structural data chosen for this was an amplitude structure generated from the file boulanger-beach.au, a 25 second seaside sound event captured at Aruga, from the OLPC CC collection by Dr Richard Boulanger.
The first tone is the simple sine wave at 320Hz. This unaltered sine wave can be easily generated, although it is very unnatural and clinical sounding (See figure 1).
Figure 1: A sine wave
The second tone was generated by adding the eco-structural data to the sine wave using the waveshaping synthesis method. The generated waveform was reduced in amplitude very slightly to avoid clipping at a couple of points. This waveform quite visibly and audibly has a certain roughness and colour, without disturbing the pitched quality of the tone (See figure 2).
Figure 2: An eco-structure applied directly to the sine wave
The third tone was generated by adding the eco-structural data to the sine wave using the waveshaping synthesis method at double depth (ie eco-structure x 2). The generated waveform was reduced in amplitude to avoid clipping at numerous points. This waveform has an identical structure to figure 2, however those same irregularities have been enhanced (See figure 3).
Figure 3: An eco-structure data applied directly to the sine wave at double the depth rate
The fourth tone is a sine wave that has been waveshaped using a random number generation algorithm. Unfortunately the waveform has now lost integrity in terms of its sine wave origin. There is still some form left, however it now contains constant zero-crossings, and needed to be halved in amplitude to reduce the constant clipping. It contains primarily white noise and can no longer function adequately as a pitched tone (See figure 4).
Figure 4: A random number sequence applied to a sine wave
The fifth tone generated is a waveform which was created with the waveshaping synthesis method using the same eco-structure as in figure 2 and 3, however in this example the data has been scaled in time, and each point is interpolated from the current data point to the next data point. The time scale factor was x 10. The generated waveform was reduced in amplitude very slightly to avoid clipping at a couple of points. The resulting waveform has retained most of its contour, however, it has more colour and timbral variation than a sine wave. (See figure 5)
Figure 5: A stretched, interpolated eco-structure applied to the sine wave
There are a number of useful applications and benefits of this process. Because the structure is preserved in such a strict structure, the same tonal quality can be applied to any sine wave or tone in a precise and repeatable manner. This application allows a composer to add a degree of irregularity very easily, whereby they can build up an entire series of tones with similar or even identical tonal qualities, to use in a musical composition. As can be seen from figures 1 to 4, the eco-structural process works as a good middle ground between pure sine waves and noise. It adds a certain degree of complexity and irregularity, without having to rely on some kind of random process.
More ideas to come later - I may also include the clipped versions of the waveshaping experiments above, as these are also very intersting sounds.