Analysis of the Ambient Noise Incident Energy Angular Distribution on Building Facades Using Microphone Array

The in-situ value of the sound reduction index of a façade element depends on the angular energy distribution of the noise impeding the façade. Generally speaking, the shape of the outdoor noise angular energy distribution is not known. Therefore, it is necessary to determine and analyze this distribution in real urban environments. This paper presents the methodology for experimental determination of the incident energy angular distribution of the outdoor noise on the building envelope. The method is based on the sound source localization using an optimized microphone array with 24 microphones and utilizing the algorithms for space-time signal processing. The methodology is applied in several characteristic terrain configurations in urban environments in order to observe the differences in the shapes of angular distributions. By using known building material characteristics and experimentally obtained shapes of the angular distributions, a prediction was performed for the in-situ value of the sound reduction index of the most common façade elements in urban environments. Such method enables the observation of differences of in-situ values of the same partition when it is placed in urban environments with different terrain configurations.