| Project/Area Number |
15360221
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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 |
Measurement engineering
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| Research Institution | Kumamoto University |
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Principal Investigator |
TORIGOE Ippei Kumamoto University, Faculty of Engineering, Dept.Mechanical Engineering and Materials Science, Associate professor, 工学部, 助教授 (40134663)
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| Co-Investigator(Kenkyū-buntansha) |
SEGAMI Takashi RION Co., Ltd., 開発部, 開発部長
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| Project Period (FY) |
2003 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥11,500,000 (Direct Cost: ¥11,500,000)
Fiscal Year 2004: ¥5,400,000 (Direct Cost: ¥5,400,000)
Fiscal Year 2003: ¥6,100,000 (Direct Cost: ¥6,100,000)
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| Keywords | Surface area / Reverberation time / Acoustic impedance / Diffusive sound field / 吸音率 / 気密 / マイクロホン / ノイズ断続法 |
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| Research Abstract |
The reverberation time of a room is in inverse proportion to the inner surface area of the room provided the sound field therein is diffuse. On the basis of this principle, the surface area of an object can be known from the measurement of the reverberation time of a container in which the object is placed. An experimental device was built on a trial basis which has the scaled-down dimensions of an actual reverberation room. A band noise is transmitted into the container from speakers and the sound pressure is picked up by condenser microphones. Using a noise switching method, the reverberation time of the container in which various sample objects were placed was measured. The experimental results showed the following : (i)the surface area of objects made of a material which absorbs sound moderately could be known from the reverberation time, (ii)the sound field within the container was not sufficiently diffuse in spite of the shape of the container ; (iii)the reverberation time of the container was affected by a slight change in the leak and the surrounding conditions, such as the atmospheric temperature and pressure. As to objects made of highly reflective material, it was known from another experiment that a method measuring the acoustic impedance of the container would work well. A new apparatus is afoot which is elaborated to attain a fully diffuse sound field and to eliminate the effect of the leak and the atmospheric temperature and pressure.
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