Sound dispersion and reverberation by a single tree

In urban spaces such as streets and squares trees may be effective in dispersing sound energy due to multiple reflections between building façades. This phenomenon can affect computer predictions of acoustic parameters such as RT and sound attenuation in such spaces. Therefore, basic research on the acoustic effect of a single tree has been conducted in this study. Field measurements were carried out for three single trees standing at sufficient distance from obstacles. Selection criteria were species, canopy size and the amount of leafs. The effect of receiver distance from the tree was also investigated. Frequency analysis of the results showed that a single tree can disperse sound energy effectively, especially above 1000Hz. Results for large and small trees with fully grown leafs suggested that RT for a large tree is higher than for a small tree – at about 0.2s at high frequencies. Results for different amounts of leafs showed noticeable changes in RT at high frequencies, above about 2kHz. With increasing receiver distance from the tree, RT decreased at high frequencies. The experiment on back scattering by trees suggested this effect is considerable.