An approach utilizing membrane materials to regulate modal characteristics of rooms

A passive approach, using membrane materials for regulating modal characteristics of rooms, is presented which improves undesirable acoustic properties in rooms at low frequencies without modifying room shape. Basic studies are conducted to examine the possibility of this approach through scale model experiment and computational analysis, where the effect on the modal distribution and the sound energy distribution in a rectangular room are investigated. The results show that the modal distribution is remarkably transformed depending on the surface density and the position of membranes. Moreover, they demonstrate some cases where high uniformity in the modal distribution and reduction in the spatial deviation of sound energy are achieved by using membranes even in the room originally having low uniformity. These findings indicate that the present approach works effectively under the proper installation of membranes, and, on the other hand, it requires the prediction of the effect in advance.