In a small room such as an operating room where there are multiple staff, some orders should be transmitted to a selected person. For achieving this without any wearable devices, we developed a voice transmission system using a parametric speaker. To use a parametric speaker in a small room, we had some experiments to investigate sound pressure characteristics in a small room and understandability of the transmitted voice with MOS. As a result, it was confirmed that the transmitted voice, which has possibility that reflect on the wall and reach to a not selected person, could be heard clearly.
