The influence of vegetation and surrounding traffic noise parameters on the sound environment of urban parks

The main aim of this study was to investigate the effects of vegetation and traffic-noise parameters on the sound environment of urban parks. Eight parks of different sizes and varying proximity to the city's ring road were selected in Antwerp, Belgium. The sound environment was evaluated with a dual approach, using primarily simulated traffic data from the surrounding roads and then measurement noise data from mobile devices within the parks. Percentile weighted sound levels were calculated considering various indicators (LA(10), LA(50), LA(90), L-Aeq) with special emphasis on background noise (LA(90)) and peak values (LA(10)). Results showed that simulated noise levels were slightly overestimated compared to the actual ones. Within the parks very small differences were found no matter whether measurement points were examined individually or aggregated on grids. Overall, background noise (L-A90) presented more fluctuations than LAID. At the same time, the average noise levels both for L-A90 and L-A10 were higher in the surrounding environment of the parks compared to the inside - most probably because of traffic sound sources and the proximity to main roads. Additional analysis was also performed within the parks for the identification of "hot" and "cold" spots for L-A90 using GIS tools. Relationships between noise levels and morphological features of the surrounding environment were also identified. The final step of analysis dealt with the effects of tree or grass areas in noise indices. The effect of additional sources other than traffic is also explained as part of the limitations and the actual findings of this research