Page  00000001 Evolution And Embodiment: Playable Instruments for Free Music Stuart Favilla Bent Leather Band Music and Multimedia Hub Victoria University ICEPA sfavilla@bigpond.com Joanne Cannon Bent Leather Band Music and Multimedia Hub Victoria University ICEPA Joanne_cannon@bigpond.com Garry Greenwood Leather Artist ggreenwood@tassie.net.au ABSTRACT This demonstration-paper presents instruments and music developed over the past ten years by the Bent Leather Band. Our approach has involved the development of music and several stages of specialised instrument prototypes for live performance. This demonstration will present the evolution of our instruments. Additionally the topics of controller mapping and the formation of the ensemble's musical style will be presented in the context of Percy Grainger's Free music. 1. INTRODUCTION As instrument-builders and musicians the Bent Leather Band has been drawn to technology as a means of inquiry and exploration. Over the past 12 years we have been developing alternate controllers and the music that they play with a spirit of frontier exploration. We have designed and built interfaces for Indian music and the performance of Gamaka [1], [2], focused our attention towards multi-parameter and virtuosic control [3], [4], and investigated over the last four years, the work of Percy Grainger through collaboration with Melbourne's Grainger museum. Grainger's legacy includes writings, recordings and the actual machines he created. Grainger's Free Music described as "music beyond the traditional constraints of pitch and rhythm" [5], was developed through the construction of many bizarre instrumental prototypes including; 6th tone tuned pianos fitted with player systems, air-pump powered reed organs capable of fine controlled portamenti, and large machines; such as the kangaroo pouch; which allowed the pitch of up to four electronic valve oscillators to be played by score of cut cardboard and paper rolls. A musician of his time, Grainger was reliant on player piano technology. A confident composer/instrument builder; Grainger chose to sequence his music on paper and cardboard rolls. The language of Free Music remains a remarkable collection of brief recorded experiments together with the instruments Grainger built. Unfortunately the limits of technology, time and money arrested the development and realization of Grainger's dream, constraints experimental musicians are all too familiar with. 1.2. Playable Instruments Our research aim was to build new playable instruments for the live performance of computer music. The goals of our research were: 1. To build an ensemble of new playable computer music instruments 2. Develop a new improvised music and ensemble. 3. Build prototypes and develop them into mature instruments. 4. Explore the language of Percy Grainger's Free Music. For our research we chose to define playable as: * expressive, * responsive, * versatile in solo and ensemble performance, * an instrument that lets you practice for hours; * an instrument that does not limit technical or musical development; * inspiring and revealing new things to the player; * an instrument that has its own sound and personality. Figure 1. Joanne Cannon and Contra-Monster

Page  00000002 The focus on playability was intended to unify all aspects of controller interface design across as many possible disciplines, e.g. Cybernetics, HCI, Ergonomics, Gesture research, Skill-development, etc. The goal is to produce a successful musical outcome. The aim was to create an experiment where several generations of prototype could evolve into an instrument, technique, musical language and set of gestures etc that are the embodiment of the music. Last of all, we felt it was necessary to engage in a musical discourse. Grainger's Free Music is not well known in Australia. Yet Grainger's contribution to electronic music is quite extraordinary. His experiments made use of piano and reed-box timbres, in addition to his valve oscillator and theremin works. Grainger's dislike for interpreters of his free music can also be understood as a desire to make and perform his own music. We know how impressed Grainger was with improvised music. After all, he brought the Ellington Band into one of his composition classes in New York, and ranked Rarotongan improvised polyphony an equal third on his top ten list. 2. INSTRUMENTS AND ENSEMBLE The instruments built consist of two separate approaches. A meta-instrument project fitted sensors to zurnas and oboes and then manipulated the sound via live signal processing. The other approach continued work on Stuart Favilla's Light-Harp controllers. The Light-Harp's hardware allows for the threshold attenuation of light-sensors. This reduces the response time of light-sensors and makes sensing beams playable of up to 200 MIDI notes a second. This means that unlike conventional keyboards and other controllers, the Light-Harp is capable of performing extremely dense and interesting textures as well as glissandi etc. The experience of building two previous instruments has brought about changes to the instruments dimension and shape. The playing surface is scalloped so the player can feel where exactly the sensors sit under the fingers. The curvature of the neck has been increased making the instrument's dimension more compact and finally, all of the ancillary controllers have been grouped to allow quick access for all controls. The 3"d generation Light-Harp supports an extensive array of ancillary controllers. These include an active electro-magnetic wammy-bar, a two-dimensional bamboo wammy-bar, two large wheels, breath control and two touch-sensitive strips. There are currently 5 independent dimensions of control. There is also a control panel of 16 assignable pots for synthesis parameter control. The instrument controls synthesizers or softsynths on a Mac G4 Tibook using Max/MSP to take care of parameter and controller mapping etc. 2.2. Serpents and Monsters The evolution of the meta-instrument controllers began with modifying simple double reed instruments with sensors. Joanne Cannon, a bassoonist, had wanted to transport her reed playing into a signal-processing environment. The first prototype instrument used force sensitive resistors and a passive magnetic proximity sensor that sensed the position of the instrument's bell. This instrument was interfaced via a MIDI control circuit to a laptop running Max which in turn controlled a number of effects units. The musical language we developed for this instrument made heavy use of delays, which we used to create additional parts. These techniques required fine control of delay times and more controllers were desired to independently control the multiple audio streams. The major drawback of this instrument proved to be its limited tonal production. This led to the idea of making long tubes with open holes. Figure 2. Leather Light-Harp with REV Exhibition helper Dan, 2002, dimensions 164 x 64 x 29cm 2.1. Light-Harp The Light-Harp uses spotlights and lasers to trace virtual strings through space for performers to play. The instrument is a MIDI controller and was originally designed by Stuart Favilla and built in collaboration with David Brown [a violin maker who has also made surfboards!] and Robin Whittle [a notable computer music instrument developer and designer].

Page  00000003 Figure 3. Serpentine-Bassoon, photo by Philip Kuruvita 2002, dimensions 33 x 78 x 26cm The second prototype instrument we built in collaboration with instrument leather instrument maker Garry Greenwood. The Serpentine Bassoon is a leather meta-bassoon, with a 2.4meter conical bore. The instrument has eight open holes; which can be used to play pitches or closed with stoppers allowing for sensors to be played instead. This instrument produced a variety of timbres reminiscent of bassoons and horns. Two contact condenser microphones were used to pick up a large variety of sounds and the signal was processed using MaxMSP via a Digi002. Dials were added for fine delay time and other parameter control and three force sensitive resistors were used to control dynamic features of the signal processing such as acoustic or delay feedback etc. The third instrument; dubbed Contra-Monster, has a 3.6meter conical bore and was built solely for signal processing. It has two built in condenser microphones, and 15 controllers including, three dials, one fine tuning dial, one fader, two joysticks and six small force sensitive pads; in the place of finger holes. The sensors have been positioned ergonomically for ease and effectiveness of use and the interface was completed with a small built in display for the performer. The ContraMonster is capable of ten simultaneous degrees of freedom. The instrument was built around a MIDIBox Plus PIC controller that was redesigned to make the circuit board smaller. A small panel of push buttons allows for the instruments controller mode to be changed allowing for over 760 possible assignments for the MIDI controller signals. 3. SENSOR MAPPING AND ENSEMBLE We discovered that mapping sensors and controllers is definitely a two-person job. We achieved our best results with one person at the computer while the other would play their instrument. We would begin our sessions with set goals and often find ourselves diverted by surprising discoveries. These discoveries would often lead to the formation of entirely new pieces. Whenever we discovered a new sound we would attempt to find a suitable controller technique and vice versa. Transferring techniques from LightHarp to Serpents would then follow with improvisation and finally recording. Our mapping strategy developed to; facilitate maximum expression, allow for very fine control, provide the player with good sensory feedback, allow for discovery and link meaningful gestures to the music being played. This sense of embodiment was essential for ensemble cueing and it also would provide clear cues for the audience to decipher some very complex and unusual textures in our music. Mapping strategies have also developed for separate musical outcomes. For example; an exploratory mapping will allow for an extensive range of transformations to be applied to a single audio source; whereas a focused mapping; may allow for one specific parameter to be controlled in a variety of different ways. Tables, buffers and other objects were applied to controller inputs, to adjust, rescale, smooth and correct the feel and responsiveness of sensors and controllers. MaxMSP patches were created for control of granular processing, real-time sampling and delay techniques, retuning, enveloping, filtering, modulation techniques, pitch-shifting and the hosting and control of audio plugins. We still have a preference for working with at least one external synthesizer module via MIDI having discovered latency limitations and unexpected crashes with many softsynths. We also created MaxMSP patches for surround sound performance. We experimented with four-channel panning, spatial location and phasing effects. We have also performed various types of spatial motion and tried to develop effective methods for presenting this to a live audience. The difficulty we have had with spatial sound still remains the disconnection of the projected sound from the players' gesture. We aim to continue working in this area. Latency and timing delays remain a major issue for our work and not only seem to inhibit skill development but also significantly reduce the players' sense of intimacy with their sound. MIDI, for all its simplicity and construction immediacy, lacks real resolution and subtlety [6]. Even with data averaging, slewing, and rescaling techniques there are always limits to what can be achieved. 4. FUTURE DIRECTIONS The next stage of our work has to clearly address the limitations of MIDI. MIDI is now cheaper and simpler to build with than I can ever remember. Modifying a MIDIBox plus circuit cost us roughly $200 in parts compared to our first MIDI microprocessor board we built in 1992 at a cost of over $5,000. The next generation of Bent Leather instruments will hopefully implement OSC, put the Mac/PC directly in the instrument and perhaps even be portable. 5. REFERENCES [1] Favilla, S. "The LDR Controller", Proceedings of the International Computer Music Conference, Aarhus, Denmark, 1994.

Page  00000004 [2] Favilla, S. "Live Performance and Virtuosic Pitch-bend technique for the Synthesizer", Proceedings of the International Computer Music Conference, Aarhus, Denmark, 1994. [3] Favilla, S. "Non-linear Controller Mapping for the Gestural Control of Gamaka.", Proceedings of the International Computer Music Conference, Hong Kong, 1996. [4] Favilla, S. "Real-time Control of Synthesis Parameters for LightHarp MIDI Controller" Proceedings of the 1997 ACMA Conference. [5] http://www.obsolete.comn/120_years/machines/free_ music machine/index.html [6] Nelson, M. Thom, B. "A Survey of Real-Time MIDI Performance", NIME Proceedings, Hamamatsu, Japan, 2004.