著者

西田 公至 福地 雅夫

出版者

公益社団法人 精密工学会

雑誌

精密機械 (ISSN:03743543)

巻号頁・発行日

vol.51, no.6, pp.1231-1237, 1985-06-05 (Released:2009-06-30)

参考文献数

6

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This paper deals with the diffracted sound field around a rectangular enclosure theoretically and experimentally, which has one or two apertures and contains sound sources inside. The sound pressure level distribution in the diffracted sound field has been computed based on Pierce's approximate expressions for sound diffraction over a single wedge or a three-sided semi-infinite barrier with two edges, and actually measured with the sound visualizing device built as a trial. In the computation, it is assumed that the sound radiation from an aperture can be expressed by a point source or distributed ones according to lower or higher frequencies. Based on these results, the applicability of the approximate expressions is examined to the estimation of the diffracted sound field around actual enclosures. The results may be summarized as follows : (1) When the distances from each edge to adjacent edge, source and observation point are larger than one third wave length, the computed results by Pierce's approximate expressions are in sufficient agreement with the experimental results. (2) The complicated directional patterns of the diffracted sound field can be grasped sufficiently in detail by using the sound visualizing method.

著者

井坂 秀治 西田 公至 齋當 建一

出版者

日本機械学会

雑誌

日本機械学会論文集. C編 (ISSN:03875024)

巻号頁・発行日

vol.66, no.645, pp.1502-1508, 2000-05 (Released:2016-02-15)

被引用文献数

1

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The purpose of the present investigation is to design an adaptive noise control muffler which has the most suitable location of secondary source. In the experiment, the distribution of sound pressure level in the muffler model has been measured by a sound visualization technique in order to obtain the maximum sound reduction by the minimum secondary sound under active control. The experimental results show that the target frequency could well be attenuated when the distance between the primary source and the secondary source is equal to the length eguivalent to one-half of the wave length of a target sound or its integral multiples.