CCRMA OVERVIEW - CCRMA - Stanford University

in plain vanilla is needed from its designers. In particular interval sets, boundary conditions and valid
parameters.
Further work
Further research and testing with toggling of different chaotic signals, randomness and parameters needs
to be done. The field of parameter estimation and optimization also brings some ideas as to how to
control gestures on Physical Models. From the composition standpoint more timbre manipulation will
be done trying to extend the flexibility of Computer Models of Musical Instrument and or acoustics.
References
• Chafe, C. Adding Vortex Noise to Wind Instrument Physical Models in Proc. of ICMC 1995, Banff,
ICMA, San Francisco, CA, 1995.
• Jaffe, D., J. O. Smith, Performance Expression in Commuted Waveguide Synthesis of Bowed
Strings., in Proc. of ICMC 1995, Banff, ICMA, San Francisco, CA, 1995.
• Sapp, C, Introduction to Improv, http:/www-ccrma.stanford.edu/craig/improv/, Center for
Computer Research in Music and Acoustics, Stanford, CA, 2000.
• Schroeder, M., Fractals, Chaos, Power Laws, W. H. Freeman and Company, New York, NY, 1991.
• Smith, J.O. Ill, Physical Modeling Synthesis Update, published in The Computer Music Journal,
Vol. 20, No. 2, pp. 44-56, MIT Press, Cambridge, MA, 1996.
• A. Restrepo, L. Zuluaga, H. Ortiz and V. Ojeda. Analytical Properties of Teager's Filter, Proc. of
IEEE Int. Conf. Image Processing, Santa Barbara, CA, 1997.
• Weeks, E. My Adventures in Chaotic Time Series Analysis, http://glinda.lrsm.upenn.edu/
"weeks/research/tseriesl.html.
6.2.5 Acoustic Research and Synthesis Models of Woodwind Instruments
Gary P. Scavone
The modeling of musical instruments using digital waveguide methods has proven to be both an accurate
and efficient technique for synthesis. Because such models are based on physical descriptions, they further
provide a useful tool for acoustical explorations and research.
Models of wind instrument air columns have reached a high level of development. An accurate and
efficient means for modeling woodwind toneholes was described in [Scavone and Cook, 1998]. Another
model of the tonehole was recently developed with Maarten van Walstijn [van Walstijn and Scavone,
2000]. It uses wave digital filter techniques to avoid a delay-free path in the model, thus allowing shorter
tonehole heights than is possible with the distributed model of [Scavone and Cook, 1998].
Previous work focused on modeling the direction-dependent sound radiation from woodwind and brass
instruments [Scavone, 1999]. The current acoustic theory regarding sound radiation from ducts and
holes can be implemented in the digital waveguide context using properly designed digital filters. Each
radiating sound source or hole requires a first- or second-order digital filter to account for angular- and
frequency-dependent pressure distribution characteristics. Sound propagation delay from the source to
the pickup is modeled with a delay line and possibly a fractional-delay interpolation filter. An additional
digital filter to model attenuation in free space can also be used. The results of this model compare well
with frequency-domain polar radiation calculations and measurements performed by Antoine Rousseau
and Rene Causse (1996) at the Institut de Recherche et Coordination Acoustique/Musique (IRCAM). A
simplified system appropriate for real-time synthesis was developed using The Synthesis ToolKit (STK)
that allows continuous pickup movement within an anechoic 3D space.
Current efforts are being directed toward the development of simplified models of conical woodwind
instruments and their excitation mechanisms. This work is being performed in conjunction with the
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