Noise: the forgotten pollutant

Smartphone apps will allow citizens contribute to live noise maps of our cities and towns

Environmental noise has for a long time been referred to as the forgotten pollutant, probably because those of us living in urban areas grow accustomed to trying to ignore it. But because of the constant and rapid development of globalised economies and cities, the world is getting noisier. This means that nations are increasingly required to map noise in their urban environments.

Noise from sources such as roadways and airports is dangerous, and studies over recent years have demonstrated many associated negative health effects, including those related to long-term sleep disorders. In particular, various forms of stress are caused by excessive exposure to noise. This will be a concern for those affected by the planned new runway at Dublin Airport.

To assess noise levels and estimate the population who are exposed to urban noise, acoustic scientists and engineers generate sophisticated noise maps, which graphically represent urban areas based on how loud or quiet they are.

According to Dr Eoin King, an assistant professor at the University of Hartford in the US who trained at Trinity College Dublin, “noise mapping is the first step in the environmental noise management process”.

By definition, noise is unwanted sound, which is loud, or unpleasant in other ways. It can be constant (think roads) or intermittent (think construction sites or motorbikes). Noise is particularly damaging near airports and around major roadways, meaning these infrastructures especially require noise mapping.

“The noise mapping process enables policymakers to determine the overall extent of noise pollution, so that appropriate decisions can be made,” says King.

Generating noise maps
Noise maps are almost entirely based on predictions, and their creation requires substantial data input.

For example, “If we know the quantity of vehicles on a road during a certain time period, along with other details such as the traffic composition and the speed vehicles are travelling at, we can calculate the ‘sound power’ of the road,” King says.