ï~~VIRTUAL BASS-CLARINET IN MODALYS
Hans Peter Stubbe Teglbjaoerg
"Composer in Research" (IRCAM)
[email protected]
KEYWORDS
Physical modelling, Realtime, Bass-clarinet, Multiphonics.
ABSTRACT
This article describes how the authors and the Modalysteam (IRCAM) collaborated to develop and implement a
realtime model of a complete bass-clarinet to be used in
the first authors composition "Rippled Reeds" for bassclarinet and electronics, that explores the relation between
an acoustic woodwind instrument and a similar virtual
one.
The intend was to create a model that allowed
fingerings to be specified generating predictable output, in
order to overcome a number of practical shortcomings
when chaining complicated forked fingerings producing
multiphonics. The model should run in realtime so that it
could be driven from the actual acoustical playing.
After a brief introduction, the first section will
reflect about the choice of synthesis method and motivate
its compositional use.
Second section describes how a model was created
from measurements of a true bass-clarinet complete with
reed, mouthpiece, tube, bell and holes, sufficiently
efficient to run in realtime on one Intel processor.
Third section describes the interface and how it
raised questions of preset interpolation and multithreading
to obtain polyphony. The conclusion draws the contours of
what was achieved and outlines possible further studies.
Thomas Goepfer
"Computer Music Designer" (IRCAM)
thomas. oep
[email protected]
In practice multiphonics pose a certain number of
problems for both the interpreter and the composer. Every
multiple sounds demands a different embouchure, their
dynamic profiles are limited, their chaining are difficult
due to the forked fingerings. They are difficult to sequence
with other modes of playing.
It would seem that other means should be searched
for; like a virtual replica, that can be played virtuoso by
the computer. The first author therefore wished to develop
a realtime model of multiphonics on a virtual bass-clarinet.
A virtual model allows not only to even out these
difficulties, but also, thanks to the rigourous control
possible with the computer, to force the multiphonic
towards other non-standard vibratory behaviours [2,8].
Thus leaving what in real life is very difficult, even barely
possible, to an extra-human device?
1.2 Why Physical Models?
After more than 20 years of practical application physical
models (PhM) still holds a great potential, esp. when more
advanced models arrive and substantial knowledge about
how to control them is developed [4]. Among its main
features must be mentioned: attractive richness and
realism in transients, stimulating complexity in interaction
between excitation mechanism and resonator, its obvious
instrumentality and possible expansion thereof, the many
vibratory behaviours possible from a single model. In the
authors view PhM offers a synthesis method which is very
well adapted and coherent with current compositional
practices.
Modal synthesis [5] was chosen because of its
modularity and user-programability, and because it
currently is the most advanced on interaction with an
extensive control in realtime. Templates allow for quick
prototyping, while a set of basic connections allow the
user to defined customised interactions. Any parameter can
be either directly modified in realtime or passed via a userdefined functional expression to their destination
parameter. Such high degree of modularity is to the
authors knowledge not available in other PhM
environments except at the coding-level itself.
It deserves mentioning that recent advances of
wind-instruments, such a brass and saxophone [6], has
stimulated the modelling of a new air-mouthpiece
interaction, that convincingly captures the non-linear
coupling between air and reed. It effectivly replaces
Modalys' rudimentary reed-connection by a more
elaborate normalised-valve connection [5].
1.
INTRODUCTION
1.1 The Composers Voice - briefly!
Does a new music require new instruments? Could we
only ask Partch, Nancarrow, Haba... or Sch6enberg [13].
Digital artists has since long left the question
behind for instrumental composers to try to make a new
music with traditional chromatic instruments. Woodwindinstruments were for the most part perfected about 150
years ago. New quartertone instruments (fx. flute, clarinet,
piano) continues to rest outside current musical practice
because of a strongly living traditional repertoire.
Sch6enberg foresaw that the emerging microtonalism
would not find into a central position of current musical
practice without adapted instruments.
Concerning multiphonics the situation is roughly
the same: current instruments are not particularly adapted.
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