A Performance of Live Interactive Computer Music and Dance

Michael McNabb
Liss Fain Dance

Artistic Description

Sudden Changes is a work for 5 dancers created in 1991 by choreographer Liss Fain for the Liss Fain Dance Company. Ms. Fain commissioned Michael McNabb to produce an original score for the work.

The dance for Sudden Changes consists of a series of episodes that originate in real life events, evolving from the choreographer's interest in reactions to environmental loss and diminishment. The movement idiom originates in descriptions of animal's behavior, their environments, and the effects of land development on the species; the parallel in human experiences of loss is the perception of and adjustment to altered boundaries.

In order to fully support the depth and range of the emotional and psychological content of the work, McNabb felt that a live musical performance was called for. It also was an opportunity to put into practice a new computer-based performance system he had been experimenting with. In this work, McNabb's solo instrumental performance is tremendously enlarged by a sophisticated computer music system to orchestral levels of musical expression. The system is designed to allow a wide variety of configurations of musical textures, rhythms, recorded sounds, signal processing, algorithmic accompaniment, etc., to be called up at will by a performer. However, none of the actual musical material is determined in advance. Everything is derived during the performance from the notes and gestures of the performer. Polyphonic accompaniment created in real time by the system can be based strictly or loosely on the harmonic, dynamic, and rhythmic structure of the performed material. Since the details of the music are largely improvised, McNabb and the dancers act as a single ensemble, leading to a level of interaction rare in the history of music with dance.

Technical Description

In the Sudden Changes performance, McNabb performs on a soprano saxophone equipped with a wireless microphone and an IVL pitch-to-MIDI converter. MIDI data from the converter and an array of foot controllers is routed through a Lexicon MRC MIDI Controller to a 68040 NeXT computer. The NeXT in turn controls a set of Lexicon digital signal processors and Yamaha synthesizers, synthesizes notes on its resident DSP, and plays stereo sound files directly from a hard disk, all simultaneously. The NeXT screen also displays a graphic score of the dancers' entrances and exits, and key musical phrases and cues.

The heart of the system is an object-oriented MIDI-processing software application, developed by McNabb, called Ensemble (see included paper). All performance data is processed by Ensemble. Received MIDI data is analyzed in order to maintain a knowledge of the current harmonic, rhythmic and dynamic contexts. Fractal-based algorithms are used to generate real-time accompaniment compatible with the current musical context. Other software objects generate timbre-shifting artificial overtones, create chord mappings, perform musical transformations, and playback recorded fragments of poetry which is processed into musical material under computer control. The system's entire configuration is periodically changed, and the foot controllers assigned different functions, by the software in response to program change commands.

Ensemble was completed during McNabb's tenure as Manager of the Sound and Music Group at NeXT Computer, and is shipped as a NeXT Music Kit programming example with all NeXT developer systems.

Technical Requirements

Sudden Changes requires a sprung wood or marley stage with a minimum area of 25 by 35 feet. Hidden wings are not required.

The musical performance requires a high-quality stereophonic sound system of sufficient power to sonically fill the space and cover the entire audience area without creating noticeable distortion, especially in the low-frequency range. If the house speaker system is located stage front, separate stereo monitor speakers must be provided on stage for both the dancers and the musician. Since the sound mix and levels are controlled directly by the musician, and the dancers' level of interaction is high, good monitoring is essential to the quality of the performance.

Performance History

May 9, 10, 11, 1991 - New Performance Gallery, San Francisco, CA
July 12, 1991 - Pt. Reyes Station, CA
Sept. 21, 1991 - Cinnebar Theatre, Petaluma, CA
Sept. 28, 1991 - Mountain View Center for the Performing Arts, Mountain View, CA
March 5, 6, 7, 1992 - New Performance Gallery, San Francisco, CA
September 1992 - International Computer Music Conference, San Jose, CA


Liss Fain
244 Corte Madera
Mill Valley, CA
phone: 415.380.9877