工場の機械・設備などから発生する騒音の低減

抄録

Noise pollution is one of the problems associated with factory noise because of its harmful impact on human health and well-being. Noise is a factor in sustainability that must be considered. The present paper focuses on effect of tapered orifices on acoustic absorption performance of perforated plate with background air space. The taper angle was 60 degree. We experimentally measured the flow rate, acoustic pressure, and transfer function using the improved acoustic impedance tube. The normal incidence absorption coefficient was calculated from the measured transfer function using transfer function methods. As the bias flow velocity passing through the orifices increased, the peak level of the acoustic absorption coefficient increased. The acoustic absorption performance has improved using taper orifices of perforated plate. The peak frequency of the acoustic absorption coefficient depended on the cross-sectional shape of hole of perforated plate.