A Study of Compression effect on the Performance of Acoustical Materials
Date Issued
2005
Date
2005
Author(s)
Chen, Shih-Kai
DOI
zh-TW
Abstract
This work studies that the sound is muffled by the acoustic material which is compressed. For yielding the sound wave equation of the material in water or air, Biot theory and the sound propagation of the solid are used. Furthermore, the variation in the acoustic parameters is presented and discussed. By considering the boundary conditions, the continuous velocity and pressure on the both sides of the material, the sound transfer matrix can be build. Than the absorption coefficient and the echo reduction can be calculated. The two parts, the sound absorptions of the material in air and water are researched separately.
In the one part, the abilities of sound absorption of the compressed material in air are investigated. The influence of the different incident angles of sound wave are also discussed in the article. As the acoustical material is compressed, the characteristics (peak or tip) of curve of absorption coefficient shift to high frequency. The value of absorption coefficient becomes low. On the other side, as the both thicknesses of the compressed and the un-compressed porous materials are the same, the ability of absorption of compressed material is better than another un-compressed material.
In the other part, the work focuses on the acoustic studies in water. As the thickness of the material varies from the pressure of water, the influences on the abilities of sound absorption of the material are simulated. In water, the ability of absorption of material is bad because the pressure of water lead the property of the material to change.
Subjects
吸音材
壓縮
acoustic material
compression
Type
thesis
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