In Japan, “open-plan” type classroom is becoming popular in elementary schools. Although this planning has various merits for educational activities, sound propagation between adjacent classrooms tends to be a serious acoustical problem. In this study,therefore, the sound propagation between closely located two classrooms connected by an open-space was investigated by numerical simulation using FDTD method. In the simulation, two classrooms and the open-space connecting them were modeled and the configuration of the rooms and sound absorption treatment on the room boundaries were examined. As a result, it has been found that sound absorption treatment on the ceiling and architectural/acoustic treatment for the wall of the open-space which makes mirror-reflection are effective to mitigate the sound propagation between the classrooms.
