Acoustic characteristics of outdoor spaces in an apartment complex

Outdoor spaces in apartment complexes are becoming increasingly important as the available area has been enlarged due to the increased underground car park. This leads to increased leisure activities in the outdoor spaces, where the acoustic characteristics play an important role in improving the overall environmental quality. This experimental study investigates the acoustic characteristics of outdoor spaces surrounded by multi-story apartment buildings. Sound attenuation and reverberation time (RT) were measured according to source-receiver distance and receiver height. The maximum source-receiver distance and receiver height were 120m and 12th floor, respectively. The results show that RT was rather long, over 4s at 500Hz and 1000Hz. On the other hand, RT at 125Hz and 250Hz was relatively short, about 0 to 3 s. Above 500Hz, RT increased with increasing source-receiver distance. Early decay time (EDT) was longer than RT over a certain source-receiver distance at about 30m. Rapid Speech Transmission Index (RASTI) decreased with increasing source-receiver distance. In terms of sound attenuation, measured SPL was up to 8dB higher compared to the open field situation, indicating the effects of multiple reflections. EDT increased with increasing receiver height although RT was similar at all receiver heights, about 3s at 500Hz.