What does the acoustic engineer say?

The sound quality of schools is attracting more and more attention in recent years. New stricter requirements for reverberation times, among other things, can mean it is necessary to use wall absorbents, says acoustic engineer Frank Lemstad.

More and more municipalities are tightening the acoustic requirements for rooms in new schools built today. That’s what civil engineer Frank Lemstad has noticed. He is employed in the Norwegian engineering company Sinus A/S, which handles sound, noise and vibration assignments on a consultancy basis. He refers to Gausel School as an example of this tendency. Sinus’ role in this was, among other things, to advise the architect whether the 0.6 second requirement (which is the equivalent of the Danish requirement for classrooms) could be achieved by using Gyproc ceilings. We are talking about a school with very open rooms. Therefore good acoustic conditions were required as compensation for the relatively weak deadening structures in the walls.”

Gyptone Sixto meets the requirement
“Our assessment is that Gyptone Sixto – which is a perforated Gyproc ceiling with very good sound absorbing qualities, compared to other traditional plaster based ceilings – could be used in normal school classrooms if it is installed right to the edge. In general, there is no great difference between mineral wool and the best plasterboards in terms of reverberation time. But other considerations - to indoor climate and look, among other things - mean that many prefer gypsum over mineral wool.”

Use wall absorbents
“But no matter what material you use a lot can be achieved in terms of reverberation time if you use wall absorbents which have a very advantageous effect on room acoustics. This is particularly the case for small rooms where the walls constitute a large part of the total surface. The trend is for minimalistic furnishing and smooth surfaces - which can cause what we call flutter echo, where the sound almost becomes like a table tennis ball between opposite (sound reflecting) surfaces. Absorbents on walls provide an ideal solution for good room acoustics.”