Improvement of sound insulation performance of roadside building facade

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The convenience of city life is greatly dependent on the road transportation. On the other hand, development of roads and progress of the motorization bring a negative property, that is, they make sound environment of the accommodation area worse and worse. In order to solve the problem, defending performance of the roadside buildings against external noises must be improved in addition to countermeasures for the noise source of automobile, development of the low-noise pavement (drainage asphalt pavement) and improvement on the road structures. In this study, the following experimental investigations were performed for purposes of systematically investigating the techniques by which roadside sound environment is improved and proposing ideal roadside buildings in the future from a viewpoint of acoustical engineering.1. Effect of Absorption Treatment of Balcony Space against Road/Railway Traffic NoiseAs the method of reducing the traffic noise, contrivance of the facade shape and acousti … More c treatment of each facade part can be applicable. However, systematic examinations for these countermeasures have not been carried out. In this study, the effect was examined by numerical calculation, scale model experiment and field measurement. As a result of numerical analysis and model experiment, the following knowledge was obtained : Over 5 dB sound reduction effect is possible against road traffic noise when the balcony eaves ceiling is treated by absorbing materials. The effect is higher as a high floor. In addition, the effect of balcony eaves ceiling sound absorption was examined and confirmed by field measurement at a multiple dwelling house which is located along a railway line.2. Experimental Study on Improvement of Sound Insulation Performance of Double WindowA double window, which is often used for raising the sound insulation performance, has disadvantage in low frequencies caused by the resonance transmission. whereas it has much higher performance in high frequencies than a single window. In order to improve the sound insulation defect of a double window in low frequencies, an idea of applying resonance type sound absorbing structure (Helmholtz resonator), which is effective in the sound absorption at low frequencies, may be effective. The applicability was investigated by an experimental examination. As a result of 1/5 scale model experiment, the transmission loss in frequency range which coincides the resonance transmission of the double window is 7 dB improved and the applicability of resonance type sound absorption structure against the resonance transmission of a double window is found.3. Measuring Method of Sound Insulation Performance of Building FacadeIn actual roadside building, low Signal/Noise ratio caused by background road traffic noise makes the sound insulation performance measurement of the building facade much difficult. Measuring methods by which the high-precise measuring result can be obtained under low S/N ratio environment are indispensable in order to examine the effect of the countermeasure proposed by this study in actual buildings. For a purpose of establish the method applicable to field sound transmission measurement, comparison examinations among the synchronized integration technique, time stretched pulse method and M-sequence modulated correlation technique were carried out by laboratory experiment and field measurement. Less