SS 25268:2023, an acoustic standard for listeners and speakers

Abstract

The sound environment in many classrooms is not good, and we know that poor room acoustics impedes learning and has a negative effect on teachers' voice health. Sound reflections in the room have a great impact on both speech intelligibility and speech comfort. SS 25268 is a Swedish sound standard for, among others, school buildings. The standard uses reverberation time, RT, to put requirement on room acoustics. There is a connection between the amount of sound absorption in the room and RT according to Sabine formula. The problem is that Sabine formula requires a diffuse sound field witch very seldom occurs in classrooms with acoustic ceilings. Another problem is when RT is evaluated with T20, the early reflections are not included, and early reflections have a great impact on speech intelligibility. The standard have been updated to a new version, SS 25268:2023. In this standard there is an opportunity for landlords to put other requirements then RT to evaluate the room acoustics. The standard have an appendix to help landlords, principals and teachers to better understand how to put the right acoustic requirements on their school buildings to create both good speech intelligibility and speech comfort.