Abstract:
In studies on some interactions between sound propagation characteristics and environmental factors underground, small-scale experiments on the sound energy distribution at an intersection of tunnels have been carried out in an anechoic room. The small-scale tunnels were made by acrylic plates, and the original surfaces of inner walls were assumed to have an acoustically hard condition, while surfaces of the walls covered by flannel were acoustically soft. Impulsive sound was generated electrically as a sound source was applied, and propagated sounds were measured by an omnidirectional microphone. The experiments were carried out under several kinds of conditions for angles at the intersection and positions of the sound source. Influences of intersection on the sound energy distribution were indicated by comparisons between the measuring points before and behind the intersection with different angles. In addition, the influences of the acoustical characteristics of the inner walls and positions of the source are also presented.