Experimental investigation of the acoustical characteristics of university classrooms

Acoustical measurements were performed in 30 randomly chosen, unoccupied classrooms at the University of British Columbia (UBC). Tests had previously been done in 46 unoccupied UBC classrooms, as well as in 10 of these when occupied by students. The results for the 10 classrooms were used to correct the “unoccupied” results to the half-occupied and fully occupied conditions. The objective of the work was to characterize the 30 classrooms, which were used in subsequent studies, to determine the acoustical quality of the UBC classroom stock and how this depends on the classroom design and the presence of students, and to elucidate characteristics of classroom acoustics relevant to optimal design. The results showed that the UBC classroom stock is of far from optimum acoustical quality when unoccupied, but is much better in the occupied condition. Generally, many classrooms have excessive reverberation and result in low speech levels, especially at the back of the rooms; in addition, they have excessively noisy ventilation systems.