Czech scientists study trees’ ability to absorb traffic noise
Trees do not only improve air quality by removing carbon dioxide from the atmosphere. They can also significantly reduce noise levels by absorbing and refracting sound waves. Scientists from Brno are currently investigating how trees could be used as sound barriers against traffic noise.
Being exposed to higher traffic noise has been directly linked to all sorts of health issues, including insomnia, depression and high blood pressure.
While most busy roads are lined with massive walls that are supposed to reduce the noise from traffic, they often don’t seem that effective and can even make matters worse by amplifying the sound.
A team of scientists from the Moravian city of Brno are currently carrying out research in Czechia’s forests to find out to what extent trees and other vegetation could help reduce the noise from traffic.
One of the team members is Blanka Hablovičová from the city’s Transport Research Centre:
“We are trying to figure out how to use vegetation along roads and railways to drown out or at least reduce traffic noise. The sound wave can travel across the noise walls and if there is nothing behind them, it can travel for miles.”
Researchers are carrying out their measurements in a forest, using a special device that releases noise into the forest through twelve loudspeakers. They use microphones to measure the extent to which the trees have reduced the noise.
Scientists will carry out their measurements at eight other locations and at different times of the year to find out which tree species composition functions best as a barrier against noise. Petr Kupec, Vice-Dean of Mendel University in Brno, says conifers are usually the most effective:
“They don't shed leaves and they provide a year-round sound barrier. However, the problem is that in times of climate change, spruces won’t be here for very long. So we are currently focusing on finding a sustainable forest mix. That is, a forest that can withstand the effects of climate change.”
Scientists also need to find out exactly how the noise spreads between trees. To do that, they first have to create a three-dimensional image of the forest using a laser scanner, explains Martin Krůček from the Research Institute for Landscape and Ornamental Horticulture.
“The scanner has a fairly powerful laser beam that it scatters around its surroundings. It also records the return of those laser beams. This way we take a picture of the entire area and based on that we create the final 3D image.”
Using the 3D images and the data on transmission of sound, scientists then create models of different types of forests. Based on these models, foresters could select the ideal mix of trees around roads and railways that would not only serve as an effective sound barrier but also withstand warmer and drier climates.
