Resumen de Classroom acoustics measurement and evaluation
Andersson Nils-Ake, Nilsson Erling
More and more people recognize that reverberation time does not on its own express the subjective experience of a space. Calculated reverberation time differs in many cases from the measured one. A systematic check of room acoustics in 19 classrooms has therefore been performed. These classrooms were situated in Denmark, Germany, Norway and Sweden. Big efforts were put on setting up a detailed measurement protocol, with established and well recognized parameters. Except a lot of physical measurements, recordings of female and male speakers in English and Swedish were included. In each classroom measurement was executed with at least two different acoustic ceiling solutions, all with and without furniture; also the empty room was checked. Results show that reverberation time might be almost equal with acoustic ceilings having substantially different sound absorption properties. This is especially noticeable in mid and higher frequencies. The correlation with traditionally calculated reverberation time is poor. On the other hand the decrease of sound pressure level from a steady state source can be estimated proportional to the amount o f sound absorption in the room.
