An experimental study of the sound field in a large atrium

Abstract

In large atria acoustic comfort is an important consideration, but it is less studied compared to other physical environmental factors. In this study, sound distribution and reverberation in a typical large atrium have been experimentally examined, revealing the basic sound field characteristics. The results show that in terms of sound distribution, at all frequencies there is a continuous decrease in sound pressure level (SPL) with increasing distance to the source, both vertically with increasing floor level, and horizontally at each floor. The patterns of SPL decrease with increasing source–receiver distance are rather complicated, and also vary considerably at different frequencies. There is a considerable difference between the maximum and minimum SPL at each floor, ranging from 31 dBA to 18 dBA from ground to top floor, but in terms of the average SPL across each floor, the decrease is only 4.4 dBA from ground to top floor. With different source positions, the average SPL in the whole atrium could be rather different, up to about 10 dBA. In terms of reverberation, at all frequencies there is generally a continuous increase with increasing source–receiver distance. With a source at the ground floor, the reverberation time variation on the ground floor could be about 100%, and in the side corridors, the reverberation time is rather long, up to about 5 s across frequencies. The decay curves are generally not linear, and the non-linearity is more significant in side corridors and also, at lower frequencies. The above features suggest the non-diffuse characteristics of such a typical atrium.