A Portrait of the Interactive Musical Instrument
Joel Chadabe
Introduction
Everyone agrees that one of the particular characteristics of the electronic musical
instrument is that it is configurable, either in its hardware structure or in its software
functioning or in both hardware and software. Exactly how configurable, of course,
depends upon the user’s skill and knowledge, and, consequently, the level at which the
user can and wants to configure the instrument. At one extreme of the configurability
scale, an unsophisticated user could purchase an instrument as an off-the-shelf item,
deciding only the sounds that it will play. At the other extreme, a sophisticated and
technically adept user might write custom software before beginning to make a sound.
Given a wide range of decisions that could be made, one particular question becomes
important: What are the principles that govern the structure and functioning of a
musical instrument and how do those principles apply to an electronic musical
instrument?
The structure of the instrument
Whether acoustic or electronic, whether made of wood or metal, a musical instrument, in
general, has three parts: a performance device, a sound generator, and a link that
connects the performance device to the sound generator. In a violin, for example, the
performance device is the strings and bow, the sound generator is the sound box, and
the link between them is the bridge. In an electronic musical instrument, the
performance device can be any “controller”, the sound generator can be any
sound-generating mechanism, and the link between them is defined in software as well as
hardware.
The crucial difference between an acoustic and electronic instrument is that the
performance device, sound generator, and link in an acoustic instrument are inseparable,
while the components of an electronic musical instrument are independent modules that
can be brought together in any configuration to function together as a system. The
inseparability of the components of an acoustic instrument is due to their interdependent
production of sound: the performance device of an acoustic instrument initiates a sound
which is conveyed by the link as acoustic information to be resonated in the sound
box. The performance device of an electronic musical instrument, on the other
hand, does not initiate the sound: it sends controls via the link to the sound
generator.