拡散音場の壁の円孔およびスリットが外部自由空間に対して示す音響指向性と透過損失について

抄録

In an another report, under the assumption that the opening from a diffused sound field has the nature as though it is a plane-like assembly of non-directional point source, the author analysed the sound intensity attenuation along the perpendicular centre line from circular and slit-like opening of diffused room, and then proved experimentally that the logical formula of attenuation being applicable resonable for diffused sound of all frequencies. In this report, the author investigated sound directivities of sound radiation from the openings of diffused room, and sound transmission through them, experimentally and theoretically. From this investigation, the author illustrated that the sound directivity of sound radiation is non-directivity for low-frequency and for high frequency range, (ka≫1) the cosθ law is applicable, and that the sound transmission loss of the opening is zero for high frequency but for low frequency (ka<0. 5) the transmission loss of the openings cannot be neglected. Thus, the openings of diffused sound field show comparatively simple natures to free field and the application of its nature to architectural noise control is made with ease with wide application.