The influence of identical room dimensions on the sound insulation at low frequencies

Abstract

At low frequencies the sound insulation between rooms is only valid for the specific case under consideration as shown in works by different authors. The expression ‘‘low frequencies’’ implies a frequency range where the rooms’ dimensions are comparable with the wavelength of sound in the rooms (i.e., normally below about 250 Hz for normal rooms). Both theoretical studies as well as experimental studies in the laboratory show that there is a substantial decrease of the sound insulation when the dimensions of the sending and receiving rooms coincide. The question arises if this decrease of the sound insulation can also be observed for the sound insulation of partitions in the field. The results are often biased by other effects such as flanking transmission or smaller differences in the fabrication of the partitions. By means of statistical studies field measurements are analyzed to show the influence of the room dimensions on the sound insulation in the field. To avoid the deterioration of the sound insulation, changes in the dimensions would be required which do not allow for symmetrical building designs as it is often preferred in practice.