Scale modelling for improving the speech intelligibility from multiple loudspeakers in long enclosures by architectural acoustic treatments

摘要

The subject of this research is the acoustics of long enclosures, such as underground stations, where one dimension is much greater than the other two. In this research, the effectiveness of a series of strategic architectural acoustic treatments for improving the speech intelligibility of multiple loudspeaker public address (PA) systems, measured by the speech transmission index (STI), has been investigated in a 1:16 scale model of a rectangular long enclosure. It has been shown that: (1) Absorbent treatments on end walls are very useful for improving the STI; (2) Ribbed diffusers are effective for increasing the sound attenuation along the length, for decreasing the reverberation from further loudspeakers, and consequently, for improving the STI; (3) Porous absorbers are more effective than the ribbed diffusers, and interestingly, with a strategically located absorber arrangement the STI could be higher with fewer absorbers; (4) Membrane absorbers can also be used to improve the STI, although the angle of sound incidence in long enclosures is relatively large; and (5) Strategic designs of obstructions can increase the STI. In general, the experiments carried out correspond to the theoretical analysis. [References: 38]