jet oscillation modelvortex shedding
A simple one-dimensional representation of recorderlike instruments, that can be used for sound synthesis by physical modeling of flutelike instruments, is presented. This model combines the effects on the sound production by the instrument of the jet oscillations, vortex shedding at the edge of the labium, and turbulence in the mouth of the instrument. The jet oscillation model used is a modification of the semi-empirical model by Fletcher [J. Acoust. Soc. Am. 60, 926-936 (1976)]. The steady-state drive of the acoustical oscillations in the pipe by the jet motion is represented by a pressure jump in the mouth of the instrument. Vortex shedding at the edge of the labium during steady-state operation is taken into account by the use of a free-jet model. The combined effects of this nonlinearity and the jet-drive model enable one to correctly predict the steady-state amplitude of the fundamental. The turbulence noise source is represented by an additional pressure jump across the mouth of the instrument having an amplitude scaling with the square of the jet velocity. This simple model appears to correctly predict the noise level and its spectrum, both with and without oscillations of the jet. The transient response of the model is triggered by the initial volume injection into the mouth of the instrument and is dependent on the steepness of the driving pressure rise.
Article paru dans : JASA: Journal of the Acoustical Society of America vol. 101