musicL

 

Andrea J. Stein, M.P.S.

Master’s Recipient: Interactive Telecommunications Program

New York University, New York, USA

ajs327@nyu.edu

 

 

 

Abstract

musicL is a real-time system for the generation and synthesis of multi-voiced compositions. Employing a set of generative algorithms, musicL disrupts our traditional expectations of what music does.

Description

musicL is a generative system for simultaneously creating music and its notation. The generative properties of musicL are determined by L-System equations (a mathematical theory developed to describe the branching and growth of trees). L-Systems are literally instruction sets that, among other things, dictate when to go forward, left, or right, by how many steps, and at what angle (see Technical Specifications). Therefore, the rules that govern musicL are a set of spatial directions which manifest sonic and visual characteristics. In other words, each unique L-System simultaneously draws a pattern and triggers sound.

Model/Prototype

In its present form, musicL allows for the arrangement of both pre-defined and random L-System compositions. The interface consists of the Elements, Stage, References, and Toolbar (fig 1).

Each Element is essentially a specific L-System. They are displayed as thumbnails which illustrate their emerging patterns. There are currently 9 pre-defined Elements, as well as one random Element. The random Element is represented by r and assembles both its instruction set and its values randomly each time it is used. Consequently, each occurrence of the random Element is theoretically unique.

The spatial coordinates of the Stage are mapped to pitch (top to bottom) and amplitude (left to right). Each Element is dragged on to the Stage to initiate its movement and sound. The Element’s vertical range of motion (and thus its pitch range) is limited to 100 pixels above and below it’s release point on the Stage. A maximum of ten Elements, in any combination, can exist on the Stage at any given time. Thus, ten occurrences of one Element is allowed, as long as the total number is not exceeded.

Figure 1: The Interface

The References (displayed in a row) indicate which Elements are currently active on the Stage. As an Element is activated, its thumbnail will appear in the “Reference Row”. Additionally, an Element can be inactivated (removed from the Stage) by clicking on its Reference.

Finally, the Toolbar contains musicL’s visual options. The patterns which develop on the Stage can be viewed differently, depending on the mode set in the Toolbar (fig 2). The Toolbar also contains a ‘pause’ button, allowing the user to observe the visual characteristics of musicL in a static form.

Figure 2a: Demonstrating ‘Full’ Drawing Mode

Figure 2b: Demonstrating ‘Connect’ Drawing Mode

Background

Generative Forms

 

Generative principles, as they apply to music and composition, are understood more clearly if discussed in contrast with classical composition techniques. Classical compositions are written with a pre-defined, specific, and desired outcome. The directions are precise and inflexible. In the end, the classical composition belongs to its composer. However, generative compositions by nature eliminate the idea of single authorship. Relinquishing control over the final product, the generative composer allows unexpected and emergent properties to arise. Brian Eno clarifies the distinction as he states “classical music … specifies an entity in advance and then builds it. Generative music … specifies a set of rules and then lets them [the rules] make the thing.”

"...in a sense it means 'putting things together', and I put them together in such a way that they're not fixed in a fixed way but flexibly work together."

                                                -John Cage, on what it means to be a composer.

In the early 50’s experimental composers such as John Cage, Earle Brown, Christian Wolff and Morton Feldman, gained notoriety relinquishing control over the execution of their art. Their motivation stemmed from “the immediate desire to deal with what sound is, rather than what the composer may think it is or decides he wants it to be.” John Cage tackled this problem by introducing chance and random procedures into his work. Feldman denounced methodology in favor of instinct. Brown’s interest in artists such as Calder and Pollock accounts for the spontaneity and open-form mobility found in his music. By providing performers with vague and often incomplete instruction sets, emphasis was, shifted away from the composer, and the individual performer was given more control.

Notation

Staff notation, used since at least the 17th century, with its origins dating back to the 9th or 10th century, is a very precise tool for dictation. The New York School’s unique methods, however, no longer fit the traditional framework of composition, and often called for new methods of notation. According to Cage, dictation does not have to be built into the notion of a score. “…if there are several parts [of a score] and there’s no fixed relationship, then there’s nothing built-in. No fixed relation built in.”

Morton Feldman was the first to use non-representational graphic notation. He divided the pitch range of each instrument into high, middle, and low, and represented each range as a rectangle on graph paper. The specific pitch and boundaries were left as decisions to be made by the performer. Christian Wolff composed one piece by writing notes vertically down the page, but had the performers read and play the piece from left to right. Cage consulted the I-Ching for note placement, while leaving rhythm and detail to the performer. Brown’s famous December 1952, a musical analogue to Alexander Calder’s mobiles, was notated by an abstract series of floating rectangles. 

musicL speaks to this tradition of unique forms of musical notation. Here, aspects of notation are separated into two parts:

1)      the L-system algorithm, which gives impetus to the music, and

2)      the visual/graphical representation of the music, which leaves artifact or record of what has transpired.

Technical Specifications

musicL was created in Java and runs as an applet in a standard web browser. The sounds are synthesized in real-time, using a Java API called JSyn (written by Phil Burke). The properties of musicL are derived from generative algorithms based on L-Systems. 

L-Systems

An L-System is a mathematical theory that describes plant development. It is represented by a series of symbols representing specific commands. The central concept behind L-Systems is the notion of rewriting. The Algorithmic Beauty of Plants describes rewriting as “a technique for defining complex objects by successively replacing parts of a simple initial object using a set of rewriting rules or productions.” All L-Systems consist of an axiom and a rule. The axiom specifies an initial condition and the rule dictates what part is to be rewritten, and by what. The depth indicates the number of times this replacement will take place.

Credits

musicL has been commissioned by to provide the score for upcoming performances with the Esse Aficionado Dance Troupe at the Merce Cunningham Dance Studio in New York City.

musicL was originally presented to the Chair and Faculty of New York University’s Interactive Telecommunications Program in May, 2003.