TRANSMISSION OF SOUND IN A LONG ENCLOSURE WITH A "T" INTERSECTION

Bends, T-intersections, U-shape turns and cross-junctions are some variations that can be found frequently in long enclosed spaces. For a receiver located around the bend in the "T" intersection, the total sound pressure consists of contributions from direct, reflected and diffuse sound waves. The direct sound contribution is dominant in the near fields in the region of sight-lines. The reflected sound field becomes more important as the receiver moves farther away from the corner of the intersection. In all cases, the diffracted sound field at the edge of the bend plays a relatively minor role along a long enclosure. The present study examines the transmission of sound along a tunnel with a "T" intersection. The characteristics of the sound fields are investigated theoretically and experimentally. A numerical model, known as an image source method, has been developed for the prediction of sound transmitted around the corner in the "T" intersection. In the numerical scheme, the phase and magnitude of all contributions from the direct and reflected waves have been included in the calculations. Indoor experiments have been carried out in a corridor with a "T" intersection for validating the theoretical formulation. Experimental results and numerical predictions for the transmission of sound of this configuration in a long enclosure are presented in this paper.