Emma Arvidsson

ABSTRACT

The effect of absorbers and diffusers in public ordinary rooms

In ordinary public rooms, such as classrooms and offices, complex tasks such as learning or following long chains of thought are performed. These activities require a good acoustic environment. In order to present the actual acoustic conditions, several room acoustic parameters have to be considered, thus increasing demands on the acoustic treatment.

The most common acoustical treatment in ordinary rooms is a suspended absorbent ceiling. Due to the non-uniform distribution of the absorbent material, the classical diffuse field assumption is not fulfilled in such cases. Further, the sound scattering effect of non-absorbing objects such as furniture are considerable in these types of rooms.

In this study, experiments were performed in a classroom mock-up using different configurations of absorbers and diffusers, with different directional characteristics. The effects on the room acoustic parameters reverberation time, T20, speech clarity, C50, and sound strength, G, were measured. It was investigated how various acoustical treatments affect reverberation time T20, speech clarity C50 and sound strength G.

The results demonstrated how absorbers, diffusers and scattering objects influence room acoustical parameters. It is shown that to some extent the parameters can be adjusted individually by using different treatments or combination of treatments. This allows for the fine-tuning of the acoustical conditions, in order to fulfill the requirements for achieving a high-quality sound environment.