POROUS SOUND ABSORBING STRUCTURE

摘要

A porous sound absorbing structure 10 includes an exterior plate 1 and a closing plate 2 in order to suppress a decrease in sound absorbing performance in a wide frequency band. An interior plate 3 is arranged between the exterior plate 1 and the closing plate 2, and air layers 4 and 5 are located between the exterior plate 1 and the interior plate 3 and between the interior plate 3 and the closing plate 2 respectively. The exterior plate 1, the interior plate 3, and the closing plate 2 are arranged while opposed to each other. Many through holes 1a and 3a are made in the exterior plate 1 and the closing plate 2 respectively. In the interior plate 3, a plate thickness t2 and a diameter Æ2 and an aperture ratio ²2 are set so as to generate an viscous effect in air passing through the through hole 3a. The aperture ratio ²1 of the through hole 1a in the exterior plate 1 is set more than 3% and not more than 50%.