二面間の狭い隙間の集合体を利用した吸音材料に関する実験的研究

概要

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In this study, the sound-absorption coefficients of the sound-absorbing structure using bundle of narrow clearances between a number of thin plates were measured for various formations and size. It is found by the experiment that, when the clearance between thin plates is reduced, the peak sound absorption value is increased and the frequency decreases. This phenomenon is related to velocity boundary layer thickness. Therefore, its occurrence is limited to clearances of 70 microns or more. When the clearances decrease in depth, the absorption coefficient is high compared with the case where clearances remain constant. This decrease also tends to improve the dip in the frequency characteristic curve of the absorption coefficient. However, when the clearances change to lateral direction continuously, this dip is not improved. When the amounts of materials constituting thin plates are identical, sound absorption performance of a folding-fan-type sound-absorbing structure is equivalent to a wedge-shaped sound-absorbing structure.
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