Good acoustics for teaching and learning

Abstract

It is important that classrooms provide good speech intelligibility and speak comfort. Being able to listen without effort is important for learning and we know that poor room acoustics is a burden that impedes learning and affect teachers' voice health. A good classroom is the Swedish forests where we can communicate over long distances without having to raise our voice. I have made several listening tests in forests and also measured the sound reflections in different forests. The results are interesting and I mean that “forest acoustics” should be the goal in terms of acoustic conditions in our schools. Many national sound standards put requirements on room acoustics in classrooms. One requirement is reverberation time, according to ISO 3382-2, and it is often evaluated with T20. Unfortunately, this is a very blunt measure, because we start T20-evaluation first after the sound pressure level dropped 5 dB. This “waiting time” is often quite long and it is a problem because we miss a lot of important information from the early part of the decay curve. Therefore, I mean we have to add C50 according to ISO 3382-1, to control if the room acoustics is good enough for teaching.