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Title:
Noise control apparatus
Abstract:
A noise control apparatus for reducing a sound volume of a noise propagating from a noise source such as a railroad includes a sound arresting wall placed apart from the noise source. Means for shifting in phase and refracting the acoustic wave of the noise is disposed at substantially the top of the noise arresting wall. The above means, for example, has a plurality of passageways extending substantially along the propagating direction of the acoustic wave of the noise and the length of the passageways varies. Through the above means, a part of the acoustic wave from the noise source is refracted and the phase thereof is shifted to be a refracted propagating sound, which thereafter interferes with the other part of the acoustic wave directly from the noise source to thereby reduce a sound volume to a great extent.
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Inventors:
Yamamoto, Tsuyoshi (Tokyo, JP)
Taniguchi, Norihisa (Tokyo, JP)
Iida, Kazuyoshi (Yokohama, JP)
Kondo, Yoshikazu (Tokyo, JP)
Application Number:
06/335617
Filing Date: 1981-12-30 Publication_date: 1984-03-13 Assignee:
JAPAN NATIONAL RAILWAY (JP)
BRIDGESTONE TIRE CO LTD (JP)
Primary Class(es):
181/210
181/288, 105/452, 104/124, 181/286
Other Classes:
E01F8/00; G10K11/175; G10K11/00; G10K11/00
US Patent Ref:
| 3080937 | March, 1963 | Garbell | 181/210 | Combined acoustic wall and exhaust gas deflector in operation of jet engines | | 4069768 | January, 1978 | Matsumoto et al. | 181/210 | Device for controlling a propagation direction of noise | | 4158401 | June, 1979 | Matsumoto et al. | 181/210 | Device for controlling a propagation direction of noise |
Other Refs:
Primary Examiner:
Fuller, Benjamin R.
Assistant Examiner:
Attorney:
Parkhurst & Oliff
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