Researchers at Chalmers’ Department of Applied Acoustics conducted a laboratory study in which test subjects performed concentration tests while exposed to background traffic noise. The subjects were asked to look at a computer screen and respond to certain letters, and then rate their perceived workload afterwards. The study showed that subjects had significantly poorer scores on a performance test, and also felt that the task was more difficult to perform, with traffic noise in the background.
says Leon Mueller, PhD student in the Division of Applied Acoustics in the Department of Architecture and Civil Engineering.
The background noise consists of two audio sequences that simulate trucks passing at a distance of ten and fifty metres. Both sequences were normalized to the same total internal level of 40 dB.
“It was the audio sequence that mimicked the closest syllables, where the sound changes dramatically as the vehicle passed by, that bothered the test subjects the most,” Mueller says. “This may be because distant traffic is perceived as a more stable drone.”
Dwellings are built near the roads now
The new findings underscore an already problematic case of the negative impact on health and functioning of traffic noise. In recent years, the distance between roads and newly built housing in Swedish cities has been allowed to shrink – a trend that can be seen internationally as well.
Put somewhat simplistically, Swedish regulations for where a building is allowed are based on the average 24-hour outdoor noise level – which means they don’t take individual lanes into account. In addition, the current regulations do not cover low-frequency noise peaks indoors, which is difficult to avoid and, according to research, is more disturbing and therefore more harmful to human health.
In one study on low-frequency noise modeling, Jens Forssén, Professor of Applied Acoustics at Chalmers, showed that such noise mainly arises from heavy traffic at low speeds, and is difficult to seal even with well-insulated windows and buildings that comply with all building codes and guidelines. for sound insulation.
Low vehicle speed can increase exposure to indoor noise
“Calculations of the different types of interfaces show that it is difficult to achieve optimal indoor acoustic environments near densely packed roads,” Forsen says. “Reducing speeds is not a solution, as our calculations show that exposure to indoor noise can increase at low speeds.”
Furthermore, Forssén says that noise and a sound environment is a factor that is often considered in hindsight in the planning process, and that there are advantages to be had if modifications are made in order to make better use of space in terms of noise pollution.
Researchers also agree that the most effective solution is to avoid urban densification in areas where traffic noise has a very significant impact on health and well-being.