The Bent Leather Band

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Instruments of the Bent Leather Band

© copyright Bent Leather Band all rights reserved 2010.

Extended Instruments

Extended instruments can be described as modified acoustic (meta), augmented, computer aided, enhanced (hyper), or hybrid instrument forms. But they can also include control-interfaces, computer algorithms for generating music, sound engines and even loudspeakers. They can be orientated to novice, playable and expert use and can be designed to facilitate skill development and enhance performance feedback.

Conventional acoustic instruments can be understood as consisting of two functional parts, the controller-interface [the part/s that are played by the musician’s hands, embouchure, etc] and the effector-mechanism [the parts of the instrument that produce the sound, also the physical structure and housing]. Extended instruments and digital musical instruments can also be described as such. However, there is nearly always the inclusion of a software intermediary defining a set of relationships, compositional algorithms or possibilities between the control interface and effector-mechanism. With digital musical instruments and systems, the term gestural-controller is normally substituted for controller-interface whereas the effector-mechanism or Sound production system can comprise a complex and configurable set of parts including synthesizers, samplers, signal processing algorithms, physical models and lastly amplifiers and even spatial loudspeaker arrays.


The Serpentine Bassoon is a unique Australian extended double-reed instrument constructed from a 2.6meter leather tube [the equivalent length of a bassoon]. This conical bore instrument was designed and built by Garry Greenwood specifically for and in collaboration with Joanne Cannon. Leather is a flexible material, allowing it to be looped and curved to achieve a suitable playable shape. Unlike the instrument's early music equivalent; the serpent [an instrument constructed from wood and then covered with leather], the serpentine bassoon is constructed from two sheets of polished leather; providing a good acoustically reflective surface inside and out. The leather tube is then wet-formed into the specific shape and heat dried. Leather is less resonant in comparison to other acoustic materials. This facilitates amplification without the usual worries of screeching feedback tones.

The Serpentine Bassoon is played with a normal bassoon crook and double reed. However the instrument has been modified with sensor controls comprising pressure sensitive pads, dials and roller wheels. The instrument’s acoustic sound and sensor information are both digitised, by separate systems and then transmitted to the computer. The computer processes the sound and aspects of this processing are controlled directly through the sensor controls on the instrument. The resultant sound is monitored by the performer audibly with the positions of rollers and tactile feedback of pressure pads providing limited feedback also.

Although this instrument is played with a conventional bassoon reed, it belongs to a family of extended instruments known as hybrids. Conventional acoustic instruments that have sensor systems added to them are usually defined as augmented [meta] instrument systems whereas unconventional instruments designed with sensor modification in mind, are appropriately defined as hybrid instrument systems. The musical sound these instruments produce is electronic and amplified, yet an acoustic signal source affords the electronic processes more life and expression. The musical sound of the serpent is projected via a loudspeaker system to an audience.

Joanne uses the instrument to produce an incredible wide range of sounds; including wild animal cries, soft-detailed plucking sounds, bassoon, horn and oboe timbres, cycling rampaging flangers, distortion tones, melodic shifting delays and echoes and all manner of bizarre oscillations, sirens, mutterings and warbling.

The Serpentine-bassoon sensors are digitized into via a Gluion high-speed network digitizer. These interfaces transmit Internet-protocol for network, wireless systems and are capable of fast responsive scanning rates (1msec). They also offer the musician 16-bit controller resolution (0-65,000 approx), for accurate and expressive parameter control. The speed, flexibility and responsiveness of these interfaces is also enhanced by their network language Open Sound Control (OSC), developed at the Centre for New Music and Technology Berkeley (CNMAT). A Gluion OSC system allows for a snapshot of the entire instrument to be sent to the computer every 1msec, rather than one single byte of serial data, as is the case with MIDI style interfaces. The Gluion interfaces are built around programmable frame gate array circuitry providing scope to reconfigure ins and outs and continue to develop the instrument into the future.


The LightHarp uses spotlights, lasers and light sensors to trace virtual strings through space for performers to play. The instrument does not make sound itself but rather it controls computers and synthesisers in performance. The instrument was originally built in fiberglas and designed by violin and instrument maker David S. Brown in collaboration with Stuart Favilla and Robin Whittle [a notable computer music instrument developer and designer]. The current LightHarp has been designed and constructed in leather by world renown, Tasmanian leather artist, Garry Greenwood.

The LightHarp is also the World's first Indian computer music instrument and resembles a veena in shape and iconographic design. Dragons [yali] have long been used as motifs in the decorative design of Indian and Asian musical instruments. The LightHarp resembles the Indian Makara with its sea-serpent like design but also takes many structural and aesthetic ideas from the contemporary veena. Included in these is the symbolic representation of the human body where the base or gourd of the instrument represents the pelvis while the instrument's neck and sensors [frets] symbolize the spinal column and vertebrae. Trumpets and flutes have often adorned Indian instruments in the past, the LightHarp's horn makes no sound however.

The LightHarp has a total of 32 light-sensor virtual strings. These strings can play separate notes, individual samples or function as frets on a single string. A schmitt-trigger mechanism greatly improves the response time of the sensors and reduces onset delays to less than one millisecond. The thresh-holds of the schmitt-triggers can be attenuated to turn specific strings on/off. This allows for the performance of modal glissandi for ragas and Asian scales. Although the LightHarp was designed for Indian music, it is also capable of performing uniquely rich and dense abstract synthesis textures and experimental micro-tonal tunings.

The 32 strings are transposable over eight octaves and tuning to various scales and paradigms is controlled through the use of the ancillary controllers. The ancillary control panel consists of 24 simultaneous channels of scanning analogue to digital control capable of hundreds of MIDI controller assignments. The main controllers include breath-control, a pitch and modulation joystick, pressure sensitive and position-sensitive touch strips, foot-control pedals, two large dial controllers [that operate concentric to each other] and an active electromagnetic proximity controller wand. The instrument is usually played with 5 independent degrees of freedom. In addition to these controllers the LightHarp also has mounted parameter control mixer based on the MIDIBox plus freeware circuit available from German hardware designer Torsten Klose. The MIDIBox plus allows for sixteen dials to control up to 760 parameters during performance.



The Contra-monster is a 3.6m conical bore hybrid contra bassoon. Unlike the serpent, the Contra-monster has no open holes for a musician to use to change pitch of the acoustic sound. The tube itself is completely enclosed and can only be used to over blow harmonics and other specialized reed effects and techniques. Instead of open holes, the instrument has three pressure sensors and a joystick controller for each hand, allowing for up to ten simultaneous and independent channels of control data to be sent to the computer for signal processing and effects control. The performer has a visual display situated near the crook end of the instrument indicating all the positions and values of the instrument plus a number of ancillary dial controllers, a slider and a large dial for fine-tuning control.

The instrument is played while slung over the left shoulder and has its own stand for performance or exhibition display. The Contra-monster has a specially designed built in microphone and also uses a conventional condenser microphone clipped to the bell. The instrument’s bell section can also be removed for travel or storage in the instrument’s suitcase size flight case. The Contra-monster’s sensor controls emphasize the use of the thumbs, digits that are developed to a high degree by bassoonists. Fingertips apply force to the pressure sensors which can be mapped in a variety of ways including feedback control, percussive attack triggers for samples and linear and log functions for various signal processing parameters. The instrument was designed to be playable and practicable. Designed on the premise of ‘many at once’ mapping where a large number of multiple simultaneous channels of control allow for tweaking an enormous range of expressive musical outcomes.

A chain of signal processing algorithms include; buffer samplers, granular pitch shifters, feedback parameters, comb-filters and delay-line generators, modulation effects, delay and loop sampling processes. Over the years, a single, mature mapping solution has evolved from a myriad of piece specific attempts. Joanne now performs an entire concert with just a single mapping and chain of signal processing programmed in MaxMSP. Current mapping work is incorporating the control of spatial motion parameters for 3D Ambisonic projection.


Working with lasers we have created many large scale LaserHarp works. Originally, these works were created for dancers and lasers were used to trigger samples and other sounds. Since 1993, we have created works for public installations, performances, workshops, concert performances and exhibitions. Since 2000 the work has become integrated with our live performance work.

Our installations provide a spatial mapping system that controls interactive performers, [computer based performing algorithms]. We use these algorithms to provide other accompanying parts to our live performance. Laser strings can be traced over huge distances. Although this creates spectacular visual effects it also creates problems in regards to focusing and tracking lasers to their respective sensors. Vibrations and wobbles can affect beam shifts easily over long distances and targeting is a nightmare. Joanne Cannon has developed systems for mounting and aiming lasers, [pictured right]. Together with sensor stands that are equipped with 60 mm lenses. Accurate tracking of lasers and sensors, has been achieved over distances of up to one hundred meters.

The interactive space is further enhanced with theremins, pressure sensitive mats and voice-tracking. Voice-tracking [machine-listening] provides our composing and accompanying algorithms with a constant stream of information. The computer responds, inverting, retrograding, harmonizing, etc. The respondent pitch stream is then fed to other algorithms that perform the stream in a musical way. These algorithms add gesture, life and performance nuance. Various setups of algorithm parameters are then saved to specific areas of the installation for either the performers or audience to play.

Within an improvised music setting, this interactive process allows the musician a moment for reflection and an opportunity to push beyond the self-imposed direction of the improvised stream. This achieves a musical result that sounds both spontaneous and highly organized. Form is governed both by the improvisation and the position of the player/s within the installation space.

Active electromagnetic wands are also used which work on a similar principle to theremins. However, our EMG controllers are tuned to resonate at specific frequencies so that multiple wands can be used all within the same space without causing any interference with each other. These controllers are scanned at much higher rates than popular ultrasound controllers, which usually have to scan very slowly in order to compensate for acoustic reflections.

copyright © 2004 Stuart Favilla and Joanne Cannon all rights reserved.


[Serpentine Bassoon, photo by S.Favilla]

[dimensions 33 x 78 x 26cm]




[Controllers for Serpentine Bassoon]







[Leather LightHarp, 2010]

[dimensions 164 x 64 x 29cm]




[Contra-monster, 2010]

[dimensions 164 x 64 x 29cm]



[Laser Installations]