A hybrid test method for measurement of airborne sound transmission loss of building partitions and elements

Single-number ratings, such as sound transmission class (STC), outdoor to indoor transmission class (OITC), and weighted sound reduction index (Rw), have been widely used to indicate the sound transmission properties of the building elements. The required transmission loss values over the frequency spectrum can be obtained from the two reverberation rooms test method (ASTM E90, ISO 10140), field measurement method (ASTM E966), or intensity method (ISO 15186). The limitations of the number of testing facilities that can provide the diffused field, minimum cut-off frequency, and other standard laboratory requirements, made the sound transmission loss measurement a costly and time-consuming procedure. In this study, alternative methods to measure the sound pressure and intensity have been investigated. The main objective of this research was to eliminate the complicated requirements of the diffused field and the room absorption measurement by averaging the direct sound amplitude at several angle of incidents and using the intensity probe to measure the sound intensity. In conclusion, the sound transmission loss, STC, and OITC values of double-glazed windows obtained from the hybrid method have been compared with predictions from the existing theory and the ASTM E90 standard test results.