Jean Kergomard, Laboratoire de Mécanique et d'Acoustique, CNRS, France: "Oscillation regimes of musical wind instruments: The points of view of the physicist and the instrumentalist"

ABSTRACT:
In their famous paper (1983),  Mc Intyre, Schumacher and Woodhouse gave a first attempt to understand the mechanism of sound production by the main classes of self-sustained instruments (bowed strings, reed and flutelike instruments) by using simplified models. A conclusion was that simplest models for the Helmholtz motion lead to an "iterated map" behavior, with the possibility to get  period doubling ("subharmonics") or even chaotic sound production. It was rather surprising, because the musical instruments players commonly produce frequency doubling or tripling, what they call "harmonics".  On the contrary period doubling, i.e. subharmonics,  is rather rare! The lecture will present simple explanation of this paradox, by distinguishing the influence of playing parameters and initial conditions. Otherwise the lecture will present some essential musical properties of self-sustained instruments, deduced from the analysis of their nature of dynamical systems. Synthesis using physical modeling can help to understand why and how subharmonics are commonly avoided by makers and players. Finally consequences of the existence of different oscillation regimes can be analyzed from several points of view, such as either this of scientists - specialists of physics ( both experimental and theoretical),  or psychoacoustics,  or synthesis- or this of makers and  players.

ABOUT JEAN KERGOMARD:
Since 1973 Jean Kergomard is researcher at Centre National de la Recherche Scientifique, successively in Paris, Le Mans and Marseilles. His dissertation (1981) was entitled: Internal and external field of wind instruments. In Le Mans he studied several topics related to propagation in ducts, such as dissipation, discontinuities, effects of periodic and random diffusors, automotive mufflers, non-locally absorbing materials for aircraft engines, and musical instruments. From 2000, in the Laboratoire d'Acoustique et de Mécanique in Marseilles,  he investigates self-sustained oscillations of wind instruments and modal decomposition in dissipative or active media.

VIDEO ARCHIVE - JEAN KERGOMARD