Sound reflections of a rigid plane panel and of the "live end" composed by those panels

概要

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For the sound reflection of a thin rigid plane panel, the integral of Helmholz and Kirchhoff gives the approximated integral formula with the known function, when the velocity potential on its back is treated as zero. Its integrals are estimated by the line integrations along the edge. An impulse response is found by the inverse Fourier transformation of the integral formula. The impulse response of such a panel in the time domain is thus numerically calculated, the transfer function in the frequency domain is obtained by its fast Fourier transformation and the calculated results are compared with the experiments. Good agreement is to be observed. Numerical caluculations are done for several kinds of rigid plane panels and their properities are discussed. When a rigid plane panel is surrounded by other rigid panels as in an enclosure, it is found that the application of a diffracted wave on Kirchhoff's boundary conditions is valid for the estimation of the first reflection. In an auditorium, the front parts and the ceiling are usually live. The sound field of the "live end" of the rigid plane panels is calculated by the superposition of the reflections, and is compared with a measured result. The information useful for auditorium acoustical designing is obtained in regard to the reflection of a rigid plane panel.
社団法人日本音響学会の論文