抄録
Various soundproof wall have been developed for noise reduction. This paper experimentally investigated the performance of broad band noise reduction by pseudo periodic soundproof forest by placing trees on the shape of Penrose tile. Transmission of an incident acoustic wave can be modulated by the sonic crystal, which mostly consists of periodic array of solid bars. Then acoustic wave of specific frequency band cannot be transmitted in the forest, and consequently band gap arises. As it is known that the diameter and lattice space of sonic crystal have the relation to both bandwidth and center frequency of band gap, firstly the influence of these parameters were experimentally verified using conventional sonic crystals. Then pseudo periodic soundproof forest by referring to the Penrose tile, which fills a plane by two kinds of simple shape tile, was introduced to obtain broad band gap. Finally it was shown that the pseudo periodic structure can widen the band gap of conventional sonic crystal, and accordingly has advantage for broadband noise reduction by sound proof forest.
