Effects of the distribution of occupants in partially occupied classrooms

The effects of the distribution of occupants in partially occupied classrooms were experimentally investigated in four university classrooms. The frequency-averaged (500-4000 Hz) absorption values per occupant were largest for the 50% occupancy cases among four percentage occupancies, 25%, 50%, 75%, and 100%, in the four classrooms. The frequency-averaged (500-4000 Hz) sound absorption per occupant values were linearly related to the perimeter values of the seating blocks in the classrooms. Perimeter values of seating blocks were proposed as a measure of the expected differences in absorption values between various seating blocks having the same areas in the classrooms. The incremental changes in other classrooms due to varying percentage occupancy can be estimated from the resulting regression equations. If the frequency-averaged (500-4000 Hz) T30 values of unoccupied classrooms values are known, one can predict the incremental changes due to varying occupancy, to several room acoustical parameter values. These would include early decay time, EDT values, early-to-late sound rations, C50 values, and sound strength, G values.