Effect of the Splayed Walls of a Room on the Steady-State Sound Transmission Characteristics

Abstract

The steady-state sound transmission characteristics in model rooms of various shapes were measured. The shape of the model was varied from rectangle to trapezoid and to quadrangle with nonparallel walls, while the interior volume of the room was kept constant. In the results, it was observed that the trapezoidal rooms in which the ratio of l to a is about 10%, where a is the mean length of the parallel walls, and l is the difference between them, are effective in decreasing frequency irregularity in the transmission characteristics. On the other hand, the sound characteristics of a fan-shaped room, adopted as an example of splayed rooms, were analyzed mathematically. The fan-shaped room with ρ0≃1.2∼1.4 has good characteristics in low-frequency region, where ρ0 is the ratio of the outer and inner radius of the room. Such a fan-shaped room corresponds to a splayed room with l/a≃0.09∼0.17. The results are in good agreement with the experimental results and our experience.