Simulation of flow through a parametrized “reed-aperture”
William J. Strong · The Journal of the Acoustical Society of America · 1984
In systems used to simulate wind instrument behavior the blowing pressure is often set to some constant value. This is equivalent to assuming that the blowing pressure source (lungs-bronchi-trachea-vocal tract) has an internal impedance that is small in comparison with reed-aperture plus tube impedance. A stylized pressure source plus reed-aperture plus tube is simulated to investigate the effects of source characteristics and tube characteristics. The pressure source is represented by one of four configurations: large cross-sectional area vocal tract, small cross-sectional area vocal tract, an /a/-shaped tract, and an /i/-shaped tract. The rectangular “reed-aperture” is parametrized so that its time variation is independent of any source or tube loading. Four “tube” loadings are simulated: a zero impedance, a resistance, an inertance, and a section of uniform tubing. Waveforms and spectra are calculated for air flow through the reed-aperture, blowing pressure, and tube pressure for the 4 × 4 = 16 possible combinations to demonstrate the effects of source and tube characteristics.