Insertion losses of balconies on a building façade and the underlying wave interactions

Urban noise exposure assessment based on principal component analysis of points of interest

Accurate qualitative and quantitative information on the characteristics of traffic noise exposure in densely populated urban areas is an important prerequisite for reasonable traffic noise control. The primary objective of this study is the development and application of a traffic noise exposure evaluation method based on points of interest (POIs). First, an automatic query arithmetic is used to acquire geospatial information, POIs data, building and network information from the webmap. Second, the attribute matrix of preprocessed POIs for the population is constructed. And the population distribution is obtained by principal component analysis (PCA) of POIs and Gaussian decomposition of demographic data. Then, the modified traffic noise line-source model is applied to calculate the noise distribution considering attenuation among buildings based on measured traffic flow parameters. Finally, with the help of the proposed noise evaluation indicators, and considering the noise function requirements (NFRs, which can be divided into four classes according to different area land-use types), traffic noise evaluation is realized. The proposed method is applied to a typical region with four NFR classes. It is concluded that the characteristics of traffic noise exposure are affected by traffic conditions, buildings, NFR classes and population distribution. And the crowds exposed to noise present aggregation effects, which are usually centered around specific buildings. In addition, POI types which people actives related suffer more serious noise exposure, and exposure is overestimated at low requirement regions without considering crowd distribution of the setting scenario.

Insertion loss of asymmetrical balconies on a building façade

The acoustical insertion loss of asymmetrical balconies on high-rise buildings was studied experimentally using a 1:3 scaled down model in the present study. Four balcony forms featured by the presence of a full-height side-wall were included. A linear loudspeaker array was adopted as the sound source. The effects of source orientation and balcony elevation angle on the insertion loss and its spectral variation were examined. The position of the full-height side-wall relative to the sound source significantly affects the balcony insertion loss. It is observed that the maximum traffic noise amplification and attenuation are both ∼6 dBA. Results also suggest that the balustrade has no effect on the insertion loss spectral variation pattern, though the insertion loss magnitude could be much reduced without it in the presence of a short side-wall. This short side-wall determines the insertion loss spectral variation pattern. Significant sound amplification is found at frequencies of the odd order transverse modes, the longitudinal modes, and their coupled modes regardless of balcony form and elevation angle. It is also found that the major acoustic mode interactions are basically independent of source orientation for balconies without the short side-wall.