/ The AIMS Project: Creative Experiments in Musical Sonification
studying it in a wide variety of creative experiments in musical sonification. The following historical example is provided to help clarify what we mean by mapping problem, and to help demonstrate the difference between musical sonification and algorithmic composition in the context of the AIMS project. Charles Dodge's Earth's Magnetic Field (Dodge 1970) has frequently been cited as an example of sonification in the context of algorithmic composition. (e.g., Childs 2003) Dodge describes his composition as "a musical setting of the succession of values that are produced by an index of the effect of the sun's radiation on the magnetic field that surrounds the earth." (Dodge and Jerse 1997) Obviously, there are many legitimate ways to approach the mapping process, that is, many different ways to sonify the magnetic field indices in the musical domain. The problem of how to interpret the indices and ultimately map them to specific musical parameters is what we mean by the mapping problem. The experimental process of creating a variety of different musical realizations based on the same succession of indices is what we mean by musical sonification. The sonification experiment ends when the composer chooses a specific mapping for use in his composition. In Earth's Magnetic Field, when Dodge decides to map the 28 possible index values into a four-octave diatonic scale on C using a Meantone temperament. (Dodge and Jerse 1997) 3 Compositional Formalisms Rather than begin our work with the sonification of natural functions produced by scientific data, we have chosen to begin our work with the study of compositional formalisms-classic implementations of algorithmic composition systems (Roads 1996) widely discussed throughout the literature. Loy (1989) describes compositional formalisms as ways of thinking. He says that procedures, algorithms, methods, and games are words we associate with the expression of musical formalisms. A formalism may be viewed as a systematic way of analyzing, ordering, or creating a compositional system. Of course, formalisms may or may not be algorithmic. Nonetheless, it seems that many traditional compositional formalisms do have an inherently algorithmic basis and are thus easy to implement on a general-purpose computer using a powerful real-time interactive composition environment like MaxMSP. Loy (1989) discusses a wide variety of examples of compositional formalisms that are considered by many to be classic implementations of algorithmic composition systems including: Guido D'Arezzo's text-setting method from Micrologus, Medieval isorhythmic motets, English rounds, Renaissance musical acrostic techniques such as soggetto cavato, the art of canon, dice music attributed to Mozart, and more modern examples such as combinatorics in the music of Schoenberg, and chance techniques associated with the music of John Cage. He also discusses the role formalisms have played in the work of Hiller and Isaacson, Koenig, Schillinger, and Xenakis, among others. We study such systems intensively, and then use them to provide appropriate deterministic and stochastic contexts for our initial experiments. 4 Application Design Issues Designing intuitive, responsive, and easy to use humancomputer interfaces for our musical sonification applications is quite a challenge. We have used Kramer (1997) and Winkler (1998) as guides in this area. De Campo, Frauenberger, and Holdrich (2004) has also been useful as it clearly identifies a number of features that a generalized sonification environment should possess. String Length and Pitch Interval (SLAPI) was selected to be the first application developed under the AIMS project because it presented numerous design and programming challenges characteristic of the musical sonification tools we plan to develop. Its interface is shown in Figure 1. Omparsa witf) 12TrT P lay D 2004 Reginad ain " b r u1 2TET o fString 2 JA4.:ý4 0 String 2 Figure 1. SLAPI-a just interval player application. SLAPI offers students of tuning theory a simple way to 'sonify" interval frequency ratios that result from rational string length divisions. These ratios are the basic building blocks of traditional tuning systems such as Pythagorean and just intonation. SLAPI's main function is to provide users with a convenient way to compare the "size" of just intervals (e.g. 3:2, 4:3, 5:4, and 9:8) with their respective twelve-tone equal tempered counterparts. After soliciting feedback from composers using early prototypes of SLAPI, we set out to design a monochord-like interface that would serve the needs of a standalone application. So that some appreciation may be gained of the level of complexity that quickly develops when one attempts to design a human interface for a MaxMSP application, Figure 2 shows SLAPI in MaxMSP's edit mode. 657
Top of page Top of page