Situated Trio: An Interactive Live
Performance for a Hexaphonic Guitarist and Two Computer Musicians
with Expressive Controllers
David Wessel, Matthew Wright, John Schott
Center for New Music and Audio Technology (CNMAT)
Department of Music,
Univ. of California, Berkeley
1750 Arch Street, Berkeley, CA, USA
{wessel, matt}@cnmat.berkeley.edu, john [at] johnschott [dot] com
Abstract:
We describe a 15 to 20 minute interactive live performance
work entitled Situated Trio for augmented guitar and two
computer musicians with expressive controllers. This work brings
into focus a number of issues concerning musically expressive
control and interaction among performers.
Keywords Gestural controllers, interactive music,
improvisation, guitar effects
INTRODUCTION
This paper accompanies and describes a live interactive
performance by guitarist John Schott and computer musicians
Matthew Wright and David Wessel, each of whom use a combination
of controllers. The proposed work involves composed situations
that define the modes of interaction among the musicians and the
musical materials available to them. Emphasis is on musical
dialog and refined control in improvisation.
Our work strives to give long-range harmonic continuity a
place in improvisation. This is not simply the privileging of
certain sonorities throughout the duration of the piece, but a
sensitivity to pitches and combinations of pitches, and their
growth over the course of a piece. Thus we have designed a range
of algorithms to analyze and respond to real-time improvised
musical data.
MUSICAL GOALS
Much of what passes for musical interactivity today merely
involves the starting and stopping of pre-canned sounds. Hard
disk playback of extended samples has replaced the tape recorder
in most electroacoustic concerts, and while appropriate to risk
minimization in the live performance of through composed music,
the rigidity of these means of performance does little to invite
a sense of musical dialog or a sense of real control
intimacy.
As a trio, our goals are to generate and shape musical
material on the spot, to provide situations that provoke a
perceivable musical dialog, and to facilitate rapid adaptation to
new musical contexts. The compositional aspect of our music
involves the design of situations, situations that specify modes
of interaction among the performers and the musical materials
available to them - scales, harmonic fields, rhythmic structures,
etc. We subscribe to the notion that we play computer-based
instruments that require a practice. We believe, as with any
musical instrument, that human skill is essential. A practice is
not only required for the development and refinement of
appropriate motor skills coupled to cognitive compositional and
improvisational strategies but also for the adaptation of the
computer-based instrument. Our practice, when it is successful,
involves a delicate balance between the time invested in
performing and time invested in instrument refinement which for
the most part involves writing software.
THE NEED FOR IMPROVISATION
We believe that the discipline and practice of improvisation
is essential to the evolution of live computer music, especially
with respect to the use of new controllers. It is clear that-with
the exception of a very few-composers have resisted writing works
for new or so called "alternate" controllers. Typical reasons
cited include general unavailability of such controllers; lack of
high level performance skills on the controllers; general
insecurity concerning the risks of live-performance electronic
music; "I'm a composer not a technologist or instrument builder";
etc. Clearly there is a kind of chicken-and-egg problem here
relating to the lack of repertoire for controllers. Indeed, it
has been this way for quite awhile and, in fact, a number of
acoustic instruments suffer from the small repertoire problem -
notably the saxophone and drum-kit. Though these instruments are
rarely used in the composed art music repertoire they are
ubiquitous in jazz and many forms of improvised music. Jazz
musicians have a long tradition of acting as instrument shapers
on such instruments. Players shape their performance practice
towards an indentifiable, personal sound. We feel that this
personal approach to sound in the improvisational context is
critical to the eventual evolution of controllers. As performers
with an interest in improvised music traditions, we have
committed ourselves to a performance practice and take the new
controllers and the development of the software that maps them to
generative algorithms into our own hands.
ENHANCED GUITAR
The enhanced guitar used by John Schott is a customized Gibson
ES 135 outfitted with a piezoelectric hexaphonic pickup system
from RMC (http://www.rmcpickup.com). The six
analog outputs of the pickups are fed to a guitar-adapted version
of CNMAT's connectivity processor that communicates with the
Max/MSP environment (http://www.cycling74.com) via
100baseT Ethernet.
The guitar pickup outputs are also fed to an Axon AX100
guitar-to-MIDI converter so that the software has access to a
high-level discrete-event representation of what the guitarist is
playing along with the actual signal. In some of the composed
situations, musical phrases from the guitar are analyzed in terms
of their pitch and rhythmic content. Specific pitch and rhythmic
patterns are defined to function as "triggers," and alter the
state of the software.
MUSICAL MATERIALS
A large suite of guitar effects has been implemented in the
Max/MSP environment, including non-linear distortion,
spatialization, convolution-based cross-synthesis, capture and
looping processes, and guitar-controlled granular synthesis among
others.
Wright controls granular , sample-based, sinusoidal model, and
resonance model synthesis via his Wacom tablet controller .
Wessel uses both asynchronous and pitch-synchronous granular
synthesis techniques, controlling them with the Buchla Thunder
(http://www.buchla.com). In
addition, variants of the CNMAT rhythm engine are used for
rhythmic structures.
MODES OF INTERACTION AMONG THE PERFORMERS
Both Wessel's and Wright's computers "listen" to the
guitarist's output. Wright uses the Catch and Throw
paradigm, recording material from Schott and, after
transformation, reinjecting it into the performance. Wessel uses
tone profile theory to determine the harmonic territory where
Schott is operating; this in turn informs his generative
algorithms about pitch material. Computers mutually inform each
other via Open Sound Control . (http://www.cnmat.berkeley.edu/OSC)
PREPARING FOR IMPROVISATION IS A COMPOSITIONAL
ACTIVITY
Our computer instruments are limited in many respects. For
example, we use some prerecorded samples, and although we can
select, layer, and transform them, their character has a large
impact on the timbral possibilities available in an improvisatory
context. Similarly, both the tablet and the Buchla Thunder
interfaces associate particular pitches with different areas of
the control surface; while improvising we are limited to the
pitches that are available on our interface.
Our design of instruments for improvisation requires making
these kinds of selections; we see this as a compositional
activity. As composers we decide in advance what materials will
be available in our interfaces; as improvisers we operate freely
within those limits.
One example is a program we call "The Great 48." This name
comes from the 48 discrete pitches available on a guitar with
standard tuning; our patch uses a form of live sampling so that
each buffer always contains the most-recently-played note of the
given pitch.
How, then, do we play the samples? It would be easy, for
example, to use a MIDI keyboard in the standard manner; this
would encourage musical gestures that are in some sense
keyboard-oriented. Instead, Schott composed a melody that uses
all 48 pitches and has other properties. We placed a copy of the
notation for this melody onto the tablet surface and wrote
software that plays each note when the pen touches it.
This melody does not need to be played as such by Wright; in
fact, in improvisation he never plays the entire melody straight
through from beginning to end. Since the melody includes all 48
pitches, it would be possible to play any melody (within the
range of the guitar) by picking out the individual notes from
wherever they lie in "The Great 48 Melody." At the same time,
this interface makes it very easy to play fragments of the
melody, and that is how it is typically used.
CONCLUSIONS
Performing with computer music instruments, like the
performance practice associated with any expressive musical
instrument, requires a practice. This practice is honed over time
and in a variety of contexts, and simultaneously develops human
skill and adapts the computer instrumentation.
ACKNOWLEDGMENTS
Special thanks to Rimas Avizienis, Adrian Freed, and Takahiko
Suzuki for their work on the connectivity processor and to Gibson
Guitar, DIMI, and the France Berkeley Fund for their generous
support.
REFERENCES
- Avizienis, R., Freed, A., Suzuki, T. and Wessel, D.,
Scalable Connectivity Processor for Computer Music Performance
Systems. Proc. International Computer Music Conference,
(Berlin, Germany, 2000), ICMA, 523-526.
- Iyer, V., Bilmes, J., Wessel, D. and Wright, M., A Novel
Representation for Rhythmic Structure. Proceedings of the
23rd International Computer Music Conference,
(Thessaloniki, Hellas, 1997), International Computer Music
Association, 97-100.
- Krumhansl, C. L. Cognitive Foundations of Musical
Pitch. Oxford University Press, Oxford, 1990.
- Wright, M. and Freed, A., Open Sound Control: A New
Protocol for Communicating with Sound Synthesizers. Proc.
International Computer Music Conference, (Thessaloniki,
Hellas, 1997), International Computer Music Association,
101-104.
- Wright, M., Freed, A., Lee, A., Madden, T. and Momeni, A.,
Managing Complexity with Explicit Mapping of Gestures to Sound
Control with OSC. Proc. International Computer Music
Conference, (Habana, Cuba, 2001), 314-317.
- Wright, M., Wessel, D. and Freed, A., New Musical Control
Structures from Standard Gestural Controllers. Proc.
International Computer Music Conference, (Thessaloniki,
Hellas, 1997), ICMA.
