Understanding Interactive Systems
JON DRUMMOND
MARCS Auditory Laboratories/VIPRE, University of Western Sydney, Penrith South DC, NSW, 1797, Australia
E-mail: j.drummond@uws.edu.au
URL: www.jondrummond.com.au
This article examines differing approaches to the definition,
classification and modelling of interactive music systems,
drawing together both historical and contemporary practice.
Concepts of shared control, collaboration and conversation
metaphors, mapping, gestural control, system responsiveness
and separation of interface from sound generator are
discussed. The article explores the potential of interactive
systems to facilitate the creation of dynamic compositional
sonic architectures through performance and improvisation.
1. INTRODUCTION
I have explored interactive systems extensively in my
own creative sound art practice, inspired by their
potentials to facilitate liquid and flexible approaches
to creating dynamic sonic temporal structures and
topographies while still maintaining the integrity and
overall identity of an individual work. Just as a
sculpture can change appearance with different per-
spectives and lighting conditions, yet a sense of its
unique identity is still maintained, so too an inter-
active sound installation or performance may well
sound different with subsequent experiences of the
work, but still be recognisable as the same piece.
However, the term interactive is used widely across
the field of new media arts with much variation in its
precise application (Bongers 2000; Paine 2002). This
liberal and broad application of the term interactive
does little to further our understanding of how such
systems function and the potentials for future develop-
ment. The description of interactive in these instances is
often a catchall term that simply implies some sense
of audience control or participation in an essentially
reactive system. Furthermore, with specific reference to
interactive sound-generating systems, there is consider-
able divergence in the way they are classified and
modelled. Typically such systems are placed in the
context of Digital Musical Instruments (Miranda and
Wanderley 2006), focusing on interface design, gesture
sonification (Goina and Polotti 2008) and mapping,
defining a system in terms of the way inputs are routed
to outputs, overlooking the equally important and
interrelated role of processing. However, the term
interactive still has relevance, as it encompasses a
unique approach to compositional and performative
music-making, hence the need for this paper, drawing
together both historical and contemporary practice.
An interactive system has the potential for variation
and unpredictability in its response, and depending on
the context may well be considered more in terms of
a composition or structured improvisation rather than
an instrument. The concept of a traditional acoustic
instrument implies a significant degree of control,
repeatability and a sense that with increasing practice
time and experience one can become an expert with the
instrument. Also implied is the notion that an instru-
ment can facilitate the performance of many different
compositions encompassing many different musical
styles. Interactive systems blur these traditional distinc-
tions between composing, instrument building, systems
design and performance. This concept is far from new.
Mumma (1967), in developing his works for live elec-
tronics and French horn, considered both composing
and instrument building as part of the same creative
process. For Mumma, designing circuits for his cyber-
sonicswas analogous to composing. Similarly, the design
of system architectures for networked ensembles such as
The Hub (Brown and Bischoff 2002) and HyperSense
Complex (Riddell 2005) is integrally linked to the pro-
cess of creating new compositions and performances.
1.1. Shared control
A different notion of instrument control is presented
by interactive systems from that usually associated with
acoustic instrument performance. Martirano wrote
of guiding the SalMar Construction – considered to be
one of the first examples of interactive composing
instruments (Chadabe 1997: 291) – through a perfor-
mance, referring to an illusion of control. Similarly,
with respect to his own interactive work Chadabe
(1997: 287) describes sharing the control of the music
with an interactive system. Schiemer (1999: 109–10)
refers to an illusion of control, describing his interactive
instruments as improvising machines, and compares
working with an interactive system to sculpting with
soft metal or clay. Sensorband performers working with
the Soundnet (Bongers 1998) also set up systems that
exist at the edge of control, due no less in part to the
extreme physical nature of their interfaces.
1.2. Collaboration
Interactive systems have recently had wide application
in the creation of collaborative musical spaces, often
Organised Sound 14(2): 124–133 & 2009 Cambridge University Press. Printed in the United Kingdom. doi:10.1017/S1355771809000235

with specific focus for non-expert musicians. Blaine’s
Jam-O-Drum (Blaine and Perkis 2000) was specifically
designed to create such a collaborative performance
environment for non-expert participants to experience
ensemble-based music-making. This notion of the
tabletop as a shared collaborative space has proved to
be a powerful metaphor, as revealed by projects such
as the reacTable (Kaltenbrunner, Jorda`, Geiger and
Alonso 2006), Audiopad (Patten, Recht and Ishii 2002)
and Composition on the Table (Blaine and Fels 2003).
Interactive systems have also found application pro-
viding musical creative experiences for non-expert
musicians in computer games such as Iwai’s Electro-
plankton (Blaine 2006).
1.3. Definitions, classifications and models
The development of a coherent conceptual frame-
work for interactive music systems presents a number
of challenges. Interactive music systems are used in
many different contexts including installations, net-
worked music ensembles, new instrument designs and
collaborations with robotic performers (Eigenfeldt
and Kapur 2008). These systems do not define a
specific style – that is, the same interactive model can
be applied to very different musical contexts.
Critical investigation of interactive works requires
extensive cross-disciplinary knowledge in a diverse
range of fields including software programming, hard-
ware design, instrument design, composition techniques,
sound synthesis and music theory. Furthermore, the
structural or formal musical outcomes of interactive
systems are invariably not static (i.e., not the same every
performance), thus traditional music analysis techniques
derived for notated western art music are inappropriate
and unhelpful. Not surprisingly, then, the practitioners
themselves are the primary source of writing about
interactive music systems, typically creating definitions
and classifications derived from their own creative
practice. Their work is presented here as a foundation
for discussions pertaining to the definition, classification
and modelling of interactive music systems.
2. DEFINITIONS
2.1. Interactive composing
Chadabe has been developing his own interactive music
systems since the late 1960s and has written extensively
on the subject of composing with interactive computer
music systems. In 1981 he proposed the term interactive
composing to describe ‘a performance process wherein a
performer shares control of the music by interacting
with a musical instrument’ (Chadabe 1997: 293).1
Referring to Martirano’s SalMar Construction and his
own CEMS System, Chadabe writes of these early
examples of interactive instruments:
These instruments were interactive in the same sense that
performer and instrument were mutually influential. The
performer was influenced by the music produced by
the instrument, and the instrument was influenced by
the performer’s controls. (Chadabe 1997: 291)
These systems were programmable and could be per-
formed in real-time. Chadabe highlights that the musical
outcome from these interactive composing instruments
was a result of the shared control of both the performer
and the instrument’s programming, the interaction
between the two creating the final musical response.
Programmable interactive computer music systems
such as these challenge the traditional clearly delineated
western art-music roles of instrument, composer and
performer. In interactive music systems the performer
can influence, affect and alter the underlying composi-
tional structures, the instrument can take on performer-
like qualities, and the evolution of the instrument itself
may form the basis of a composition. In all cases the
composition itself is realised through the process of
interaction between performer and instrument, or
machine and machine. In developing interactive works
the composer may also need to take on the roles of, for
example, instrument designer, programmer and per-
former. Chadabe writes of this blurring of traditional
roles in interactive composition:
When an instrument is configured or built to play one
composition, however the details of that composition
might change from performance to performance, and when
that music is interactively composed while it is being per-
formed, distinctions fade between instrument and music,
composer and performer. The instrument is the music. The
composer is the performer. (Chadabe 1997: 291)
This provides a perspective of interactive music
systems that focuses on the shared creative aspect of
the process in which the computer influences the
performer as much as the performer influences the
computer. The musical output is created as a direct
result of this shared interaction, the results of which
are often surprising and not predicted.
2.2. Interactive music systems
Rowe (1993) in his book Interactive Music Systems
presents an image of an interactive music system
behaving just as a trained human musician would,
listening to ‘musical’ input and responding ‘musi-
cally’. He provides the following definition:
Interactive computer music systems are those whose
behaviour changes in response to musical input. Such
responsiveness allows these systems to participate in live
performances, of both notated and improvised music.
(Rowe 1993: 1)
1Chadabe first proposed the term interactive composing at the
International Music and Technology Conference, University of
Melbourne, Australia, 1981. From http://www.chadabe.com/bio.
html viewed 2 March 2009.
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