2.6 Grain Order
 

A very important factor in making granular textures is the order in which the grains are placed. When dealing with sound samples, and the samples need to be kept more or less in their original form, the grains must be placed in that manner, running from the beginning to the end of the sample. Another method is to randomly scatter the grains in an attempt to create some totally new texture. This is another area where statistical distribution can play an important role.
 
 

2.7 A look at a multidimensional texture
 

The following diagram (fig 2.10) contains a multidimensional texture that I have created for analysis. It contains a number of different granular sounds combined into one multidimensional texture. It is comprised of just 3 types of grain contents:

There are just 4 types of envelopes:
 
Apart from the grain functions the texture is created by changing the parameters of the texture, such as the density, the duration of the grains, the frequency and the amplitude.
These parameters are all assigned different algorithms to determine how the parameter conditions are met. The algorithms consist of different ramps, envelope shapes, random numbers and complex signals.

 

Varying these parameters provided the entire texture.
 
 
 
    Frequency 

(20-22,000 Herz) 
 Time (0-295 seconds) 

        Fig 2.10: 'Where the Wind Meets the Sea'. Composed by Timothy Opie. On Track 2 of the accompanying CD, or play below. Spectral graph made in Cooledit96 for PC.
 

See appendix 4 for a picture of the original idea, and the Csound files that made the texture. The Csound scores are detailed in the types of functions and tables used.
 

The composition starts off with rectangular shapes in which random numbers are distributed. The amplitude fades in and out, creating a high pitched whisper.

The lower section rumbles.

The first two streams of the composition contain a changing variety of sonic effects. Other streams join in as the grain density increases. The grain duration gets shorter, and the random pitches become more varied resulting in a large spectrum where all streams meet. This quickly contracts to an extremely small spectrum, of one stream. It then explores different shapes, and frequencies, splitting again into two streams.
 

The main focus of the composition is on grain densities, grain durations, and frequency. Each envelope is tried with each grain content providing a range of different sounds. As can be seen on the spectral graph, very distinct shapes are created within the boundaries of the mask (See Appendix 4). The mask is not as detailed as those created by Truax, but it does show how masks can be used.1
 

2.8 Summary of the Grain

It has been demonstrated that the grain consists of an envelope and contents. Of course these things are inseparable. If one part is taken away it is no longer a grain. The control methods involved in the contents and the grain have been discussed. The control methods of the texture have also been discussed. The problem of having too much control, and statistical ways to get around this problem have been explored. As has the use of multiple layers in granular textures. It is now time to look at the events that took place to allow the conception of granular synthesis.
 


 
1If you look at the Csound score in appendix 4, you can go through it to see what parameters where used where. It gives a basic idea of the range of sounds that can be created in a texture with only a few grain sources.