Using optimized surface modifications to improve low frequency response in a room

A case study of improving sound energy distribution at low frequency in a small orthogonal room is presented in this paper. The effects of the geometric modifications of wall surface on the sound frequency response have been investigated in depth. In order to find the optimal modifications for the wall surface, an optimization procedure, based on finite element analysis, has been developed. The uniqueness of this method is that it takes both modal redistribution and sound diffusion into account during optimization process. As a result, the promising improvements of sound frequency response have been obtained at the frequencies around 100 Hz in all rooms tested, particularly in those where the serious modal concentrations are met. The maximum reduction of sound fluctuation in such a room could reach a mount of 4.6 dB. The work opens up the possibility of improving low frequency sound quality by a means that considers both modal changing and surface scattering at same time.