An approach utilizing membrane materials to regulate modal characteristicsof rooms

A passive approach, using membrane materials for regulating modal character istics of rooms, is presented which improves undesirable acoustic propertie s in rooms at low frequencies without modifying room shape. Basic studies a re conducted to examine the possibility of this approach through scale mode l experiment and computational analysis, where the effect on the modal dist ribution and the sound energy distribution in a rectangular room are invest igated. The results show that the modal distribution is remarkably transfor med depending on the surface density and the position of membranes. Moreove r, they demonstrate some cases where high uniformity in the modal distribut ion and reduction in the spatial deviation of sound energy are achieved by using membranes even in the room originally having low uniformity, These fi ndings indicate that the present approach works effectively under the prope r installation of membranes, and, on the other hand, it requires the predic tion of the effect in advance. (C) 2000 Elsevier Science Ltd. All rights re served.