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(31)　EFFECTS OF SHAPES OF RADIATIONAL APERTURE ON RADIATION CHARACTERISTICS
　　　　　Bulletin of the Faculty of Engineering Hokkai-Gakuen University, 26,pp.373-382,1999-2.

The acoustic characteristics of acoustic tubes with protrusions at the radiation end are computed by FEM simulation. In the first experiment, two different shapes of the protrusions, a symmetrical and an asymmetrical shape with respect to the vertical, are investigated. Frequency characteristics of the radiation impedance are computed from simulation results. The simulation results show that the results of FEM simulation are in good agreement with our measurement results. The proposed 3-D radiational model is useful for analysis of the acoustic characteristics of human speech. In the 2nd experiment, the protrusion is attached to our 3-D vocal tract model. The vocal tract shape corresponds to the Japanese vowel /a/. The cross sections of the tubes are elliptic in shape. The simulation results show that the vocal tract transfer function of the FEM results is different from our previous FEM results and 1-D analytical solution.