This study used scale model experiments to investigate the insertion losses of balconies on a building façade in the presence of ground reflections. The experiments measured both A-weighted broad- and narrowband insertion loss spectra. The underlying wave interactions/interferences and their couplings with and without reflections from the balcony ceilings were also examined in detail, and these findings were related to the dimensions and elevations of the balconies. The findings indicate that the ground and ceiling reflections and their interferences with the direct sound play very important roles in shaping the frequency characteristics of the insertion losses. Strong sound attenuation can be attained with a carefully designed geometry and acoustical properties of the balcony and the balcony ceiling.

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.