Digital Modeling of Bridge Driving-Point Admittances from Measurements on Instruments of the Violin Family

Thu, 10/18/2012 - 5:30pm - 6:50pm
CCRMA Classroom [Knoll 217]
Event Type: 
DSP Seminar
Be it to understand the physical implications of design choices by makers, or to simulate their behaviour by computer, measuring and studying bridge input admittances of violin-family instruments is not a new topic. In the contex of sound synthesis via physical modeling, a string termination at the bridge can be realized by designing a digital filter whose response resembles the admittance measurement. However, obtaining accurate admittance models as efficient, passive digital filters still remains a difficult task. In this talk we present a modal analysis/synthesis methdology for designing passive digital realizations of two-dimensional driving-point admittance matrix measurements on instruments of the violin family. A first estimation of modal frequencies and bandwidths is obtained by spectral peak processing, and then optimized by introducing linear constraints in a gradient descent routine. Then, modal gains are estimated via solving a semidefinite program while enforcing passivity. Obtained digital filters, which provide high modeling accuracy at low-order, are used to implement a loaded waveguide termination through which four two-dimensional string models get coupled.

Esteban Maestre was born in 1979. He received the B.Sc. and M.Sc. degrees in electrical engineering from Universitat Politecnica de Catalunya, Barcelona, Catalonia (Spain), in 2001 and 2003 respectively, and the Ph.D. degree in computer science and digital communication from Universitat Pompeu Fabra, Barcelona, Catalonia in 2009. From 2001 to 2006, he was a Lecturer at Universitat Politecnica de Catalunya. During 2003 and 2004, he carried out research at Philips Research Laboratories, Aachen, Germany. From 2004 to 2010, he was a researcher (Music Technology Group) and a lecturer (Department of Information and Communication Technologies) at Universitat Pompeu Fabra. In 2008, he was a visiting researcher at the Center for Computer Research in Music and Acoustics, Stanford University, where he is now a postdoctoral fellow working on gesture synthesis for automatic control of bowed string physical models. Concurrently, he is also with the Music Technology Group (Universitat Pompeu Fabra, Barcelona) where he directs research on ensemble performance analysis and supervises Ph.D. students funded by large-scale EU Comission research projects. His research interests include sound analysis/synthesis, gesture control of virtual musical instruments, performance modeling, and auditory-motor interaction.
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