Noise exposure is a growing concern for highly urbanised societies, with a growing body of research identifying the ways in which it influences human health.
Fixed and permanent noise walls act as long-lasting acoustic barrier that are engineered to significantly reduce noise levels in various environments and require minimal upkeep.
They allow for customisable designs to cater for the specific geography and noise levels emitted, as well as having many ecofriendly options that are made from sustainable materials.
Vegetated noise barriers are also effective as they increase the barrier’s absorption and reduces the propagation of sound – customised placement of tree rows behind traditional highway
noise barriers or layers of vegetation on rigid noise walls can reduce noise levels by up to 12 decibels.
Environmental noise from traffic has been linked to sleep disturbance, cardiovascular disease, cognitive impairment in children and stress.
Some of these have important flow-on effects, with higher levels of local noise leading to people taking more sedatives, having more headaches and becoming more prone to accidents.
The United Nations Environment Programme (UNEP) 2022 report on emerging issues of environmental concern identified noise pollution as a top environmental risk to health across all age and social groups and an addition to the public health burden.
The report noted that the adverse effects of noise on public health covered a broad spectrum of outcomes, ranging from mild and temporary distress to severe and chronic physical impairment.
It is estimated that in Europe 22 million people suffer from chronic noise annoyance, while 6.5 million suffer from sleep disturbance.
A study by the University of West England (UWE) Bristol found that manmade sounds such as vehicle traffic could mask the positive impact of the sounds of nature on people’s stress and anxiety.
Dr Paul Lintott, Senior Lecturer in Conservation Science at UWE Bristol and study lead, said: “Our study provides valuable insights into how natural and anthropogenic soundscapes affect anxiety and stress in urban areas.
“It highlights a critical aspect of urban living that is often overlooked – the need for access to natural sounds amid the constant noise of city life.”
Victoria’s West Gate Tunnel project – which is currently under construction – has uniquely designed noise barriers which aim to protect residents’ privacy, reduce traffic noise, and provide an attractive outlook.
In response to community feedback, a noise standard of 63 decibels was developed specifically for the project, so that it responds to the unique noise issues and community needs along the project’s route.
The proposed design for the barriers uses textured concrete and acrylic panels of pale blues and greens, which allow light to pass through.
A review of noise barriers based on geometries and materials found transparent barriers had a lower perceived loudness and noise annoyance compared to opaque barriers.
It also found that the utilisation of waste materials such as plastic, rubber, bottom coal ash, etc., gave high noise attenuation along with low-cost efficiency.
A research project conducted in the Netherlands developed walls that have grooves of varying depths, which reduce horizontal noise by bending it upwards in the vertical direction.
This noise diffracting technique allows for smaller barriers to be used to deflect more noise away from surrounding people and homes – a one-metre-high barrier is able to reduce noise by seven to nine decibels.
Measures to mitigate noise differ in effectiveness but reduction at the source is the most effective, including restriction of traffic flow or speed, quieter vehicle engines and low-noise road surfaces.
Barriers placed near the source or receiver can also significantly reduce noise.
Both traditional and innovative barrier materials, such as those recycled from plastic or car tyres have proven effective; fibreglass from decommissioned wind turbine blades in Denmark have shown a barrier effect reduction of traffic noise levels by between six and seven decibels.
Other engineering solutions include pathway intervention, which aims to obstruct the pathway between the sound’s source and the receiver.
Noise barriers as well as the use of acoustic insulation materials and architectural features in buildings can obstruct the path of noise propagation.
A report by the Danish Road Institute noted that noise screening could constitute an actual physical barrier in a town or housing area, both visually and physically dividing the town and preventing communication between its various districts.
The author said: “If thoughtfully planned, noise barriers and embankments can create visually attractive and functional urban spaces.
“Various strategies for the adaptation of noise barriers and embankments to urban and rural surroundings can be used. One strategy is the planting of trees and other vegetation so that the noise barrier fits in with its surroundings.
“Another strategy is to allow the noise barrier to bring out the lines and forms of the landscape or town to the roadside, while a third strategy is to make the noise barrier stand out as a striking and visible addition to its surroundings through a conscious selection of colours and forms.”