Trees as Noise Barriers

Trees can help block noise pollution and can be used to dampen the negative effects of noise from traffic in urban areas. They are less expensive and more attractive than solid barriers like mounds of earth or fences. Trees create a visible barrier between the hearer and the noise source, which can lessen the human perception of noise. People may be less conscious of noise when they are unable to see the source. Trees mask noise through the rustling of branches, leaves, and needles in the wind. Also, the sounds of animals that use trees, such as birds, can help decrease surrounding unpleasant noise such as car horns, car engines, and other traffic noise. 

Image by Adege from Pixabay

Researchers have pinpointed the most effective tree species to combat noise. In a sound absorption test conducted on the barks of 13 tree species in a laboratory, the conifer was more successful at absorbing sound than the other broadleaved trees. Scientists found that, out of all of the trees, the larch, a conifer, was the best at using its bark to absorb noise. The qualities that contribute to noise absorption included tree age, bark thickness, and bark roughness, with tree age and bark roughness being the most important factors. Having tree species with barks that are better at absorbing sound can help reduce noise pollution and alleviate the detrimental impact of industrial and traffic noise. 

Sources:

https://www.bbc.com/news/science-environment-52139333

https://www-sciencedirect-com.proxy.lib.pdx.edu/science/article/pii/S0003682X20300372

https://www.trees.org.uk/Trees.org.uk/files/8c/8c69f212-a82e-424b-96d1-c8ff6dc02403.pdf

Top image of Central Park, New York, by JodesJ from Pixabay