| Résumé |
The development of real time modeling of musical instruments
points out the problem of their gestural control. When
a suitable device is attached to the physical model,
the natural interaction that exists between a musician
and his instrument is preserved, enabling the parameters of the model
to evolve following the gestures of the performer.
Starting from these observations, in this paper we propose
new solutions to control our real time physical model of a bowed
string instrument.
We use a graphical tablet with different transducers that
simulate the behaviour of the bow and the left hand of a violinist.
A pressure and inclination sensitive pen that moves on the tablet, as
if it was a bow moving on the strings, controls bow force, bow velocity,
distance from the bridge and inclination of the bow.
Using the pen, we are able to reproduce all the bow strokes like
staccato, balzato, martellato in a natural way.
In particular, even bow strokes obtained by skilled musicians only after
years of practise come out immediately and intuitively from the model.
For example, fast repeated balzatos are obtained simply by rubbing the
tablet with the pen backward and forward and releasing it, while
staccato is reproduced by moving the pen with a high bow velocity and
stopping it almost instantaneously.
Another interesting property of the tablet is the possibility of working
with two transducers simultaneously and independently.
We take advantage of this fact to control the model as a left hand of a
violinist, responsible for pitch changes, vibrato and glissando.
We have experimented with various devices for the left hand such as a
glove or a pen. One advantage of these controllers is that they register
changes in inclination, while maintaining the same position on the
fingerboard,to control vibrato.
It is remarkable that the combination of the pen and the "lefthand"
transducer allows for bowing several strings simultaneously or
sequentially as with a real violin.
We show how even a basic model, with a simple non-linear function
for the bow-string interaction and a linear part that simulates the
propagation of the waves in the strings, gives realistic bow strokes,
thanks to the excellent properties of the control.
To further refine the synthesis, we also present more
elaborated models, that include the measured resonances of the body
of the instrument, fractional delay lines for a precise tuning,
and more precise bow string interactions.
The model, which runs on the real time platforms jMax and Max/MSP,
is used by musicians who appreciate its easy apprenticeship and the
satisfactory results it provides, especially in concert situation.
All these qualities will be outlined during the demonstration.
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