NEW MEASUREMENT METHOD REDUCES NOISE STRESS
A new Swedish method for measurement, involving several independent parameters, may be the answer for hundreds of thousands of people suffering from noise stress. The noise-reducing steps that have been taken so far by using the new method have had a positive effect on room acoustics and have decreased the number of problems arising on account of noise. This was apparent at an international acoustics seminar in Sweden hosted by Saint-Gobain Ecophon, in which 200 of the world’s foremost acousticians took part.
Impaired hearing, tinnitus, sleep disturbance and reduced learning ability are just some of the problems that arise in schools and pre-schools with excessive noise levels. Most classrooms are not designed for today’s modern, integrated teaching
In England, a study has been made of the effects of noise on teaching and learning:
“We used amplifiers in a number of classrooms and supplemented the study by questioning pupils and teachers,” says Julie Dockrell, University of London, during her presentation at the acoustics seminar. “We compared their perception of noise with objective data, since it’s a question of behavioural change, and thus got a good picture of the negative effects of noise on learning.”
For over a hundred years, reverberation time has been the general gauge for describing the acoustic environment in public premises. “Measuring only the reverberation time does not give a complete picture of a room’s sound environment,” explains Erling Nilsson, Doctor of Technology and researcher, who has worked on this problem area for 15 years. Using only the reverberation time to characterise the acoustics of rooms with sound absorbent ceilings is not sufficient.”
“We supplement this by measuring the diffuse sound waves that are dispersed by all the objects in the room. This means that the choice of noise-reducing fittings such as ceiling, walls and furniture is of considerable significance. If there is an awareness of these prerequisites, it is also possible to be much more effective in improving the sound quality.”
On this basis, Erling Nilsson and the international acoustics company Saint-Gobain Ecophon, which has a subsidiary in Ramsdell, Basingstoke Hampshire, carried out a number of tests, first in a laboratory and then in classrooms, canteens, hospitals and open-plan offices.
In the premises that were tested with the new method and that were subsequently improved with absorption material, the room acoustics are now significantly better.
One example is a school in Gothenburg where there has been a marked improvement in the sound environment. Johan Berntsson, School Head, says: “We had staff developing tinnitus but they are now free of symptoms. Parents say that their children are calmer and that they speak more quietly at home as well. Our working environment is much more pleasant now.”
As a gauge for sound environment quality in public premises, the new method is also of interest in connection with the development and updating of the sound standards of several European countries.