| Project/Area Number |
10450213
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| Research Category |
Grant-in-Aid for Scientific Research (B).
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Architectural environment/equipment
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| Research Institution | Kyushu Institute of Design |
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Principal Investigator |
FUJIWARA Kyoji Faculty of Design, Kyushu Institute of Design, Professor, 芸術工学部, 教授 (00038978)
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| Project Period (FY) |
1998 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥5,100,000 (Direct Cost: ¥5,100,000)
Fiscal Year 2000: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1999: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1998: ¥2,800,000 (Direct Cost: ¥2,800,000)
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| Keywords | road traffic noise / noise barrier / 土木音響学 / 道路交通騒音 |
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| Research Abstract |
The aim of this paper is to develop a noise barrier, which gives large excess attenuation despite its low height. For realizing the barrier two different mechanisms were employed. One is T shape in barrier cross-section and the other an acoustic soft surface.
The acoustic soft surface is obtained by arranging 1/4 wave length acoustic tubes over the barrier surface, but the sound pressure level at the tube mouth becomes quite large at the frequency a little lower than the design frequency. To reduce this pressure increase the fibrous material was attached at the mouth. Although this material reduced the pressure increase, the pressure release at the design frequency was also rose a little and then the excess attenuation by the barrier reduced for wide band noise.
Another method to reduce the pressure increase was examined. This method was to cancel the pressure increase of the acoustic tube of certain depth by the pressure release of another acoustic tube of different depth. Therefore many acoustic tubes of different depths were arranged over the top area of T shape barrier of 2m widths. The shortest tube is 12cm and the longest 60cm. The numerically obtained excess attenuation by this barrier was quite large.
Then the performance of this barrier for road traffic noise was compared with that of really existing huge noise barrier of 9m in height, 6.3m bended portion to roadside and 14m in total cross-section. In the case of our soft T shape barrier the barrier needs only 6m in height and 2m in width to get the same excess attenuation as that of the huge barrier. This fact was verified by both of the numerical calculation and experimental study.
As mentioned above, the aim of this study was almost satisfied, and a new barrier system of T shape and acoustic soft surface was obtained. Unfinished work is to derive a simple prediction method of the excess attenuation of the barrier in the case when it is constructed along the real road.
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