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Noise Abatement

The role of ecosystems in abating noise pollution.

 

Millennium Ecosystem Assessment Service Category

Regulating Services

 

What is noise abatement and how is it derived?

The distance between an individual and the source of a noise along with any physical barriers (e.g. vegetation, buildings, rocks, hills) will influence (through absorption, refraction and perception) the degree of noise experienced.

Noise pollution can originate from many sources such as road, rail, boat and air traffic, machinery, neighbourhood and recreational noises. In general, noise pollution increases with increasing population (and the increase of medium to high density housing). Sound easily travels over open spaces (e.g. water, hard substrates). On a landscape scale, the distance between an individual and the source of a noise, along with any physical barriers (e.g. vegetation, buildings, rocks, hills) will influence (through absorption, refraction and perception) the degree of noise experienced. For instance, the further people live from an industrial area they are less likely to be affected by associated noises than those living directly next to it. Similarly, are those persons living on the other side of a hill.

Table 1 below presents the magnitude different ecosystem functions contribute to abating noise pollution (relative to other ecosystem functions). Plants in themselves do little to reduce noise transmission in the urban environment. A row of trees in an urban environment offers almost no sound reduction from passing cars. But plants, acting in concert with other natural systems, do have a measurable effect on sound. They absorb and diffract some background noise by scattering and diffusing sound and reducing the reverberation time from noise as it bounces off hard paving and reflective building surfaces. Again on the landscape scale, large patches of vegetation (in which distance is a significant contributing factor) can improve the provision of noise abatement. 

A combination of landscaping features, thermal insulation materials, street furniture, planting materials and other structures can abate urban noise by scattering, absorbing and diffusing sound. Natural materials (raw materials) can be used that absorb toxins and increase oxygen while creating a more pleasant, quiet and healthy human environment. For example, materials like cork that absorb toxins could be combined with eco-productive walls designed to disrupt sound waves and vibrations while allowing people to see through the screens. Of course, the frameworks in which materials such as cork are used need to be designed so that they are not consumed by birds and insects.

 

Table 1:The relative magnitude (to other ecosystem functions) each ecosystem function contributes to Noise Abatement.

Ecosystem Function Category Ecosystem Function 0
1
2
3
4
5
Regulating Functions
Gas Regulation





Climate Regulation





Disturbance Regulation





Water Regulation





Soil Retention





Nutrient Regulation





Waste Treatment and Assimilation





Pollination





Biological Control





Barrier Effect of Vegetation





Supporting Functions
Supporting Habitats





Soil Formation





Provisioning Functions
Food





Raw Materials





Water Supply





Genetic Resources





Provision of Shade and Shelter





Pharmacological Resources





Cultural Functions
Landscape Opportunity





 

ARE HUMAN INPUTS REQUIRED TO FACILITATE noise abatement?

Sometimes the perception of noise can be as important as the decibels - art work on city buildings complimented with real trees; a mix of plants around the perimeter of hard surfaces; green space in urban areas - can create a more subtle and pleasant environment.

Human design inputs are required because noise is a product of human systems of design. The main causes of noise in urban areas are from systems of transport. To address this, some railways and freeways have expensive, single-function sound barriers to diffract sound waves. More multi-functional proposals include enveloping the rails in modular green ‘tunnels’, or providing green passages over and under freeways. A modular system, similar to portable road barriers, could increase the area available for ecological functions by capitalising on the roof and walls of such tunnels to create ‘ecological space’. These modules could act as water collectors and filters, air purifiers, overpasses for wildlife and native ecosystem preservation, while serving acoustic functions. 

It is important to remember that, as in many instances of passive environmental design, plants for noise mitigation do not appear to work well - only because it has been under-designed to optimise inputs against outputs. Resource efficiency therefore demands design for multiple ecosystem services, not just one problem in isolation. For example, where there is adequate space plants and compost have been combined with earth berms which can contain underground and above ground sound barriers and functional landscape features. These attenuate noise levels significantly while supporting ecologically appropriate biodiversity habitat. The costs of abating noise can be amortised by creating other ecosystem services and amenities at the same time.

Living or planting walls, also known as vertical landscapes, can be combined with acoustically-sensitive compost and container systems to reduce sound transmission between and within existing buildings. Living roofs of substantial depth can reduce the noise of airplanes while reducing storm water run off, supporting endangered species and mitigating the urban heat island effect. There is also a new organic sheeting material that provides better soundproofing by diffracting sound waves that would otherwise be transmitted through walls or doors. Likewise, a careful combination of ‘landscape furniture’ supporting plants, such as vertical timber trellises, can confuse sound waves along the lines of ‘staggered stud’ walls. 

Sometimes the perception of noise can be as important as the decibels however. A mix of plants in a variety of locations around the perimeter of hard open spaces can create a more subtle and pleasant environment. It should not be forgotten that indoors, soft screens of planting, in place of hard office space dividers, can make a measurable objective and psychological difference also.

 

Are there any barriers to people receiving this ecosystem service and its benefits?

The main barrier to noise abatement is that noise in the urban environment has been accepted as inevitable or ‘natural’. Noise has been a design parameter for industrial processes, but not for urban design. While urban noise can be mitigated through creative landscaping, building and green infrastructure design, the problem is that past approaches have focused entirely on mitigation.

First, efforts have been made to reduce noise production at the source through, for example, less start and stop traffic, controls on flight routes, or improvements in industrial equipment. Second, defensive measures have been undertaken to reduce noise impacts by reflecting sounds using hard barriers or structures. While these are important, a third more positive approach has been largely overlooked. This approach is to design different forms of buildings and landscapes, or eco-retrofit existing urban areas, not only to absorb sound but to increase the ‘sounds of life’ or white noise. 

This ecosystem service provides many benefits that contribute both directly and indirectly to the well-being of the SEQ community. The Constituents of Well-being this ecosystem service contributes to are presented in Table 2 below. Further information on these constituents and how ecosystem services contribute to them can be obtained by clicking on the links in the table.

 

Table 2:The relative magnitude (to other ecosystem services) Noise Abatement contributes to each constituent of well-being.

Well-being Category Constituent of Well-being 0
1
2
3
4
5
Existence
Breathing            
Drinking            
Nutrition            
Shelter            
Health
Physical Health            
Mental Health            
Security
Secure and Continuous Supply of Services            
Security of Person            
Security of Health            
Secure Access to Services            
Security of Property            
Good Social Relations
Family Cohesion            
Community and Social Cohesion            
Freedom of Choice and Action
Social and Economic Freedom            
Self Actualisation            

 

HOW DO WE KNOW IF WE ARE DEGRADING, MAINTAINING OR IMPROVING noise abatement?

 

A buffer of trees between a road and a residential precinct reduces noise pollution by creating white noise (natural, unobtrusive sound such as wind through leaves).

Links to other publications and websites

Integrated Living Systems
Qld Government - Noise
The Colour of Noise
Noise in Ecosystems

While noise can easily be measured, nature is a complex system that does not yield to linear reductionist forms of analysis. Thus, the effect of plants on noise depends upon a myriad of variables. However, because plants have multiple benefits, the focus should be on designing low-maintenance, multi-functional landscaping systems that provide many ecosystem services simultaneously. For example, urban walls or buildings could be eco-retrofitted with ‘green scaffolding’, which wraps an otherwise energy inefficient building in an ecosystem for food production, heating and cooling, insulation, weather reinforcement, air and water cleaning and so on. Noise abatement would then be a by-product of eco-productive urban systems.

Tools are already available for the monitoring and measuring of the acoustic properties of the natural soundscape. GIS and habitat sensors can be used to map the effectiveness of green infrastructure in order to determine the best locations for positive interventions. However, we need to measure progress, not just in terms of reducing urban industrial noise, but also in terms of the net increase in the sights, sounds and signs of nature. 

 

How is this ecosystem service currently managed in SEQ?

For information on noise abatement as an ecosystem service, many universities run courses and conduct research in landscape planning, architecture, environmental engineering and urban design. These centres are rich sources of information on creative and innovative ways to abate noise pollution through the use of ecosystem services. There is no single government authority in Australia with overall responsibility for controlling or reducing noise pollution.

The federal government is responsible for noise pollution from aircraft and emission standards for new vehicles. The National Occupational Health and Safety Commission has a national code of practice (Noise Advisory Standard 2004) providing advice on noise management in the workplace. Neighbourhood and recreational noise are usually the domain of police and local councils. In SEQ, the level of industrial and urban noise is regulated under the Environmental Protection Regulation 2008, the Noise Abatement Act 1978 and individual local government Acts. The World Health Organisation is also a good source of information.