Effect of facade shape and acoustic cladding on reduction of leisure noise levels in a street canyon

Environmental noise is a rising problem in contemporary cities, and the awareness of its consequences on human health is growing. Although the leisure noise generated by people talking in the streets is not generally the most relevant noise source, it has a significant impact in certain urban scenarios, such as nightlife areas. Buildings facades are the primary surfaces upon which the sound emitted within the street is reflected and their design contributes to the reduction of noise level over their fronts. By means of acoustic performance-based design, this research investigates the sound level reduction provided by the shape and the acoustic cladding of an urban facade in front of a talking noise source in a street canyon. The results highlight the screening effect provided by the balconies and the benefits of the application of sound absorbing material on the noise reduction over the facade. Up to 1 dB decrease in the mean level over the entire facade has been achieved with balconies depth of 1.5m compared to 0.9 m, with a maximum abatement of 2.8 dB at the highest floor. When the entire facade is cladded with sound absorbing material, the mean noise level decrease is up to 10 dB over the facade and up to 3 dB over the opposite one. These reductions are much higher than those obtained by increasing the sound absorption properties of the street paving, that is limited to 1.5 dB averagely, thus underlining the crucial role of facade design in outdoor noise mitigation.