Page  491 ï~~A Single Performer Controlled Interface for Electronic Dance / Music Theatre Mark A Bromwich Department of Music The University of Huddersfield Huddersfield West Yorkshire HDI 3DH ENGLAND SMUSMAB,Pegasus.hud.ac.uk Abstract: The Navigator represents an attempt to create a new and specific form of dance/music theatre through the creation of a sensitised performance space. This project grew out of a desire to find a more cohesive form of collaboration between director (Julie Wilson) composer (Mark Bromwich) and performer (Chris Batstone). The aim was to develop a 'true' dialogue between music, live electronics, and performance. Custom designed 'Controllers' and 'Virtual Instruments' were developed and built by the author augmented by commercially produced Proximity Sensors developed by The University of York's Electronics Centre. This Paper describes the technical realisation of the performance. Implementation: The conversion of Sensor to Midi information was achieved by using the newly developed 'Midi Creator' - an analogue to Midi interface. Each Creator has 14 inputs detecting switch or 0 - 3.2V proportional signals. An integrated digital audio/sequencer program was required to provide the comnmnication link with the Midi information generated by the Midi Creators. This program was also required to hold pre-composed material as digital audio soundfiles, and midi note information to be transfonmed / manipulated in real time by the perfonmer. Opcode's StudioVision Pro was chosen for the host program due to it's excellent 'Midi Keys' system of external event triggering and control. The potential problem of having a large number of midi sensors sending 'live' information via the midicomputer interface was overcome by using a midi controlled router/patchbay. As all of the Midi data was to be routed through the computer ports a way was needed to change the program's 'device thru' allocation whilst the program was running, and from the program itself. As 'midi keys' can change the 'thru instrument' using an external midi signal, a way of routing midi data from one of the macintosh's output ports to an input port was required which would not result in 'midi overrun errors'. A solution was to send program changes to the PC 1600 midi controller to recall a setup string which in turn could be connected to an input port thereby affecting instrument changes. Lighting information was stored in sequences as System Exclusive messages conforming to the Midi 1.0 Show Control protocol. Projection Performance Set-up ICMC PROCEEDINGS 199549 491

Page  492 ï~~System Hardware: Roland JD990 sound module. Yamaha SY99 Synthesiser. Korg Wavestation A/D sound module. Peavey PC 1600 Midi Controller, Roland SE70 digital multi effects module - providing real time transformation of the performers voice. Computer System Macintosh hex c/w 12Mb ram,500Mb HD & Digidesign Audiomedia 2. Lig;hting System Strand GSX lighting console c/w Communique' Midi Show Control software. Audio System Mackie CR1604 console with OttoMix Midi automation. Sensors/Virtual Instruments. Midi Gesture - ultrasonic transmitter/receiver. Midi Sensor - capacitive proportional controller. LDR proportional controllers. X.Y resistive 'joystick controller. Conductive foam - pressure transducer. Velocity Wands. Set mounted switch triggers and pressure pads. Creator Software. Version 3.0 c/w 2 extra EPROM cards each giving 8 extra 14 channel control configurations. The EPROM cards were programmed to provide additional generation of Midi controller information for the required real time timbral control. The Virtual Instruments: The 'Cosmic Instrument' was built as a virtual Theramin and consists of a vertical structure resembling the Experimental Instrument proposed by Robert Fludd (1574-1637). A l0kfl multi turn potentiometer was mounted at the base of the structure wound with radio drive cord to a pulley wheel arrangement mounted at the top of the scale. The potentiometer was connected to one control voltage input on the PC 1600 midi controller which was programmed to send a simple on/off message together with a variable controller message to control the filterfrequency of a self oscillating filter on the SY99 synthesiser. The increase and decrease in pitch of a pure sinusoid emulating Theramin's original instrument was thus realised. The 'Velocity Wands' consisted of 2 metre lengths of 50mm plastic tubing with Mercury switches embedded in 4 axis at one end. Due to the inertia required to affect a closed contact at any or all of the 4 axis an extremely effective visual choreographic sequence of triggered samples could be realised. The 'Joystick Controller' an old apple II resistive XY joystick was acquired and modified to receive and send the correct range of voltages to a Midi Creator. The stick itself was extended to 3 metres in length so that a large physical movement was required to affectthe required timbral changes from the Roland JD990 sound module. The creator itself used 2 inputs programmed to send 2 different control number messages from the X and Y inputs. LDR Sensors an arrangement of light dependent resistors connected to simple potential divider networks were used to great effect to generate switch on/off commands and proportional signals. Performance Concept: Both the music composition, the script, choreography and modes of performance adhere to the concept of a devolving state of communication set against a progressive complexity cf developing technology brought about by the passage of time. In the first three sections of the performance'virtual instruments' are incorporated into the set, or are used as props, which are played' by the performer, and as such are recognised by the audience as possessing the same characteristics as instruments. As the technology becomes more complex, 'virtual instruments' disappearand are replaced by hidden triggers and sensory devices which are concealed within the set. At this point the 'set' is given the ability to speak through the use of samplers, and independently amplifies the sub text' of the dramatic narrative through short sequences of composed music, triggered as an integral part of the dramatic action. Conclusions: While the amount of technology in the show is extensive, the effect on stage is dynamic and often illusionary - sometimes the cause ofan effect is obvious, at other times it is difficultto detect and rationalise. Sound and light sequences seem to interact spontaneously with each other, and the overall effect is one of total fluidity within the exciting dynamics of dramatic tension. This collaboration has given birth to new ideas and possible ways of working in the future such as using Midi Show Control more intensively to control such things as hydraulics~robotics and video effects. Since the show was premiered the artists involved have collaborated further on the design and construction of an interactive Midi sound sculpture installation commissioned by Wakefield City Art Gallery. 492 2IC MC PROCEE D I N G S 1995