Study on the methods of environmental noise monitoring

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In the "Environmental Quality Standards for Noise" revised in 1998, the basic concept of noise impact assessment was changed and equivalent continuous A-weighted sound pressure level which is widely used in the world was adopted as the noise index. Besides this standard, "Environmental Impact Assessment Law" was issued and enforced in 1999 and environmental impact assessment has become mandatory for large-scale development projects. Based on these legal movements, this study was started for the purpose of monitoring or predicting the situation of environmental noise exactly using equivalent continuous A-weighted sound pressure level and indicating the results of the examination objectively. The contents of this study are as follows.(1) Study on the prediction and assessment for road traffic noiseAs a basic study for the improvement of the "ASJ RTN-Model 1998", which is the standard model for the prediction of road traffic noise in Japan, field measurements were performed to examine the effect of heavy vehicles and the noise distribution in vertical direction in urban areas. Besides, sound attenuation effect by various types of noise barriers and embankments and noise prediction around semi-underground roads and intersections with much complicated conditions were analyzed by the methods of numerical analysis and scale model experiments.(2) Study on the measurement methods of noise propagationIn sound propagation measurement outdoors, the effect of the meteorological conditions on sound propagation characteristics cannot be neglected. In order to deal with this problem, the application of such signal processing technique as Time-Stretched-Pulse method was investigated theoretically and experimentally.(3)Study on the prediction of construction noisesRecently, the noise generated by construction works has become a subject of environmental assessment and the prediction method has to be developed. In this study, the basic examination was performed on this topic.