Intelligibility in classrooms

Due to hygiene requirements in modern school buildings, the materials used in classrooms and auditoriums have to be durable and hard. The materials must also be very strong to withstand the abuse from the young pupils, resulting in a very poor acoustical environment with low intelligibility and stressful working conditions for both teachers and pupils. Through the RASTI method, it is possible to measure the intelligibility in the room taking both reverberation, early decay, and noise into account. This paper shows a practical use of the RASTI method suggesting how to develop a modern classroom that meets all hygiene requirements and at the same time provides good acoustical performance and excellent intelligibility for communication. The principle is to apply sound‐absorbing material, out of reach of the pupils, to surfaces where no reflection is needed, while reflection from the middle part of the ceiling and back walls is utilized. After treatment, the RASTI figure is over 0, 70, which is in the upper e...