Noise Control Methods Using Mitigation Measures

Noise pollution refers to unwanted or harmful sounds that disrupt the natural environment or human health. It comes from sources like traffic, construction, loud music, or industrial activities. Excessive noise can cause stress, hearing problems, and interfere with daily life.

Noise pollution occurs when sound levels exceed a certain threshold, becoming intrusive, annoying, or harmful to human health and the environment. It’s a form of environmental pollution, even though it doesn’t leave physical waste like other pollutants. Prolonged exposure to excessive noise can lead to hearing loss, sleep disturbances, increased stress, and even heart-related problems.

Noise control involves strategies or measures to reduce or manage unwanted sounds. This can include using barriers, soundproofing materials, quieter machinery, or enforcing laws that limit noise levels in certain areas. The goal is to minimize the impact of noise on people and the environment.

An integrated noise policy should include several noise control procedures which includes measures to limit the noise at the source, noise control within the sound transmission path, and protection at the receiver‘s site, land-use planning, education and raising of public awareness.

Ideally, countries should give priority to precautionary measures that prevent noise, but they must also implement measures to mitigate existing noise problems. The most effective mitigation measure is to reduce noise emissions at the source. Therefore, regulations with noise level limits for the main noise sources should be introduced.

Examples of Noise Pollution

1. Traffic noise: Cars, trucks, motorcycles, and honking horns on busy roads can create continuous loud sounds, especially in cities.

2. Construction sites: Equipment like jackhammers, drills, and heavy machinery produce loud, disruptive noise.

3. Airports: Airplane takeoffs and landings generate high levels of noise that can affect nearby residential areas.

4. Industrial activities: Factories and industrial plants with machinery, generators, and equipment can be sources of constant noise.

5. Household noise: Lawn mowers, vacuum cleaners, and loud music or television sets are common examples in residential areas.

6. Public events: Concerts, sporting events, and festivals can cause temporary spikes in noise levels.

7. Urban environments: Places with heavy pedestrian activity, such as markets, parks, and public transportation hubs, often have high levels of noise.

Effects of Noise Pollution

1. Health issues: Constant exposure to loud noise can cause hearing loss, increase blood pressure, and lead to stress or sleep disturbances.

2. Wildlife disruption: Animals rely on sound for communication, navigation, and survival. Noise pollution can interfere with these natural behaviors, sometimes leading to changes in migration patterns or habitats.

3. Reduced productivity: In workplaces or schools, excessive noise can cause distractions, lower focus, and reduce overall productivity.

Different Sources of Noise Pollution and their Mitigation Control Measures

1. Road traffic noise

Limits on the noise emission of vehicles have been introduced in many countries (Sandberg 1995). Such limits, together with the relevant measuring methods, should also be introduced in other regions of the world. Besides these limits a special class of low noise trucks has been introduced in Europe.

These trucks follow state-of-the-art noise control and are widely used in Austria and Germany (Lang 1995). Their use is encouraged by economic incentives; for example, low-noise trucks are exempted from a night-time ban on certain routes, and their associated taxes are lower than for other trucks.

However, the main noise from traffic on highways is rolling noise. This may be reduced by quiet road surfaces (porous asphalt, drain asphalt‖) or by selection of quiet tires. Road traffic noise may also be reduced by speed limits, provided the limits are enforced.

For example, reducing the speed of trucks from 90 to 60 km/h on concrete roads would reduce the maximum sound pressure level by 5 dB, and the equivalent sound pressure level by 4 dB. Decreasing the speed of cars from 140 to 100 km/h would result in the same noise reduction (WHO 1995).

In the central parts of cities a speed limit of 30 km/h may be introduced. At 30 km/h cars produce maximum sound pressure levels that are 7 dB lower, and equivalent sound pressure levels that are 5 dB lower, than cars driving at 50 km/h.

Noise emission from road traffic may be further reduced by a night-time ban for all vehicles, or especially for heavy vehicles. Traffic management designed to ensure uniform traffic flow in towns also serves to reduce noise.

Low-noise behavior of drivers should be encouraged as well, by advocating defensive driving manners. In some countries, car drivers use their horns frequently, which results in noise with high peak levels. The unnecessary use of horns within cities should be forbidden, especially during night-time, and this rule should be enforced.

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2. Railway noise and noise from trams

The main noise sources are the engine and the wheel-rail contact. Noise at the source can be reduced by well-maintained rails and wheels, and by the use of disc brakes. Sound pressure levels may vary by more than 10 dB, depending on the type of railway material.

Replacement of steel wheels by rubber wheels could also reduce noise from railways and trams substantially. Other measures include innovations in engine and track technology (Moehler 1988; Öhrström and Skånberg 1996).

3. Aircraft noise

The noise emission of aircraft is limited by International Civil Aviation Organization (ICAO, 1993) which estimates maximum potential sound emissions under certification procedures. In many countries, non-certified aircraft (i.e. aircraft not fulfilling the ICAO requirements) are not permitted and such aircraft may not be registered again.

The use of low-noise aircraft may also be encouraged by setting noise-related charges, that is, landing charges that are related not only to aircraft weight and capacity, but also to noise emission. Night-time aircraft movements should be discouraged where they impact residential communities. Particular categories of aircraft; such as helicopters, rotorcraft and supersonic aircraft pose additional problems that require appropriate controls.

4. Machines and equipment

Noise emission has to be considered a main property of all types of machines and equipment. Control measures include design, insulation, enclosure and maintenance. Consumers should be encouraged to take noise emission into account when buying a product.

Declaring the A-weighted sound power level of a product would assist the consumer in making this decision. The introduction of sound labeling is a major tool for reducing the noise emission of products on the market.

5. Education and public awareness

Noise abatement policies can only be established if basic knowledge and background material is available, and the people and authorities are aware that noise is an environmental hazard that needs to be controlled.

It is, therefore, necessary to include noise in school curricula and to establish scientific institutes to study acoustics and noise control. People working in such institutes should have the option of studying in other countries and exchanging information at international conferences.

Dissemination of noise control information to the public is an issue for education and public awareness. Ideally, national and local advisory groups should be formed to promote the dissemination of information, to establish uniform methods of noise measurement and impact assessment, and to participate in the development and implementation of educational and public awareness programmes.

6. Land use planning

Land use planning is one of the main tools for noise control and this includes:

a. Calculation methods for predicting the noise impact caused by road traffic, railways, airports, industries and others.

b. Noise level limits for various zones and building types. The limits should be based on annoyance responses to noise.

c. Noise maps or noise inventories that show the existing noise situation. The construction of noise-sensitive buildings in noisy areas, or the construction of noisy buildings in quiet areas may thus be avoided.

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In conclusion, road traffic noise may also be reduced by speed limits, provided the limits are enforced. The use of low-noise aircraft may also be encouraged by setting noise-related charges. Land use planning is one of the main tools for noise control With careful planning, noise exposure can be avoided or reduced.

A sufficient distance between residential areas and an airport will make noise exposure minimal, although the realization of such a situation is not always possible. Additionally, noise abatement policies can only be established if basic knowledge and background material is available, and the people and authorities are aware that noise is an environmental hazard that needs to be controlled.

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