Speech levels in meeting rooms and the probability of speech privacy problems

Speech levels were measured in a large number of meetings and meeting rooms to better understand their influence on the speech privacy of closed meeting rooms. The effects of room size and number of occupants on average speech levels, for meetings with and without sound amplification, were investigated. The characteristics of the statistical variations of speech levels were determined in terms of speech levels measured over $10s$ intervals at locations inside, but near the periphery of the meeting rooms. A procedure for predicting the probability of speech being audible or intelligible at points outside meeting rooms is proposed. It is based on the statistics of meeting room speech levels, in combination with the sound insulation characteristics of the room and the ambient noise levels at locations outside the room.