Three-dimensional space sound absorbers using microperforated panels

A microperforated panel (MPP) is one of the most promising alternatives of the next-generation sound absorbing materials. It has a large potential for various use. However, its conventional use is to place it with a rigid-back wall and an air-cavity in-between. Therefore, its arrangements in a room are limited on to room boundaries, and in some cases, this may cause a problem in room design and its strength: for example, in Japan, it is not allowed by regulation to use it for a wall. Therefore, the authors have been looking at the possibility for using MPPs for space sound absorbers without any backing structure. This can allow MPPs for wider use: a three-dimensional shape MPP space absorbers can be easily produced if a suitable material is used. They can be placed easily in various places: they can be put on the floor or hang from the ceiling, etc. Besides, MPPs can be made of designable, lightweight materials, which can add designability to the absorbers. In this paper, the main results of our studies o...