Biblioteca de la Guitarra y Cuerda Pulsada

The implementation and control of a real-time guitar synthesizer are discussed in this thesis. The implemented guitar sound synthesizer is a physics-based model of the acoustic guitar. The real-time model is implemented on a workstation computer platform using object-oriented programming paradigm, and a new protocol is developed for the control of the synthesizer. The thesis introduces the sound production principles and the structure of an acoustic guitar. The playing techniques are shortly described placing main emphasis on the classical guitar playing. A computationally efficient and physically relevant model of the acoustic guitar is then described. The model is based on the digital waveguide synthesis method, formulated as a single delay loop model.

Commuted waveguide synthesis method is described as a way of including the guitar body and the plucked excitation in the model. Also digital filter implementation of the most prominent body resonances is discussed. The guitar model implementation using C++ programming language is reported. The implementation is contained in two class libraries, one for the general purpose signal processing units and another for the special instrument model classes. The implemented synthesis model contains six dual-polarization string models running at the sampling rate of 22050Hz, and two shared body resonators running at the rate of 2205Hz. General issues on signal processing on a general purpose workstation platform are also discussed. The discussion on the guitar model control starts with a review of the parameters of the synthesis model. The implications of dynamically altering the values of the model s parameters are described along with the means of reducing the severity of such artifacts. Current sound synthesis control protocols are described, a new text-based protocol with hierarchical addressing mechanism is developed, and its application to the guitar model is discussed.

HELSINKI UNIVERSITY OF TECHNOLOGY Department of Engineering Physics and Mathematics

Implementation and Control of a Real-Time Guitar Synthesizer