647 4点マイクによる多孔板の吸音特性の実験的研究(遮音・吸音・減衰評価)(OS.10 : ダンピング)

概要

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Sound absorbing mechanism of perforated panels was studied. Firstly, assuming viscous flow in a cylindrical tube (Poiseuille flow), characteristics of sound propagation in a punching hole, i.e. propagation speed of sound, effective density, and wave number, were derived analytically utilizing Kirchhoff theory. Then normal sound absorption coefficient of the perforated panel with air space depth behind it was calculated, considering small holes occupied by acoustical viscous medium. The 0.5mm-thick perforated panel with 150 micro meter diametrical holes was made and evaluated its sound absorption coefficient. Secondly, amplitude dependence of sound absorbing characteristics of 0.8 mm-thick perforated panel with 2 mm diametrical-hole was discussed. Transfer matrices of perforated panel, determined by means of four-microphone measuring technique, are shown that identified damping characteristics is proportional to particle velocity with some constant at laminar flow region. They are compared with equation derived by T.H.Melling [4] and reasonably good agreement is achieved.
一般社団法人日本機械学会の論文
2001-08-03