In situ measurement of noise incidence angle distribution at the building envelope

Measurements of in situ sound reduction index of a façade defines noise source's incidence angle of 45&_circe;&_pm;5&_circe; (ISO 140-5). Seeing as the sound reduction index is dependent from the angle of incidence, it is of interest to examine to what extent results obtained with such incidence represent real sound insulation performances of a façade in different circumstances. The paper presents the results of monitoring and analyses of noise incident energy angular distribution on the surface of building façades in real urban environments. A custom non-uniform, planar microphone array consisting of 24 microphones is designed and constructed for this purpose. Angular distributions of noise energy are presented for a number of situations. Specificities of the microphone array as a measuring tool are discussed, as well as algorithms used for obtaining the required spatial resolution of the monitoring system.