Noise Preventionand Attenuation
Noise is defined as an unwanted sound. An ambient noise is a noise that joins noise and is associated with a given environment and normally a composite of all sounds from sources that are near and far. Any kind of noise that is abnormal and tends to disturb or irritate the human beings is then considered to be noise pollution.
Noise is a product of a technological civilization that is not desired. Noise surrounds people wherever they go. The traffics, the roar, the passage of airplanes, buses, and trains, the crowd talking, the working of industries, and many others, all these tend to deafen our ears.
The Environment (Protection) Act. 1986, under Sec. 6 mentions ‘the Rules to Regulate Environmental Pollution.’ It explains the maximum limits of concentrations of different pollutants of the environment that are allowed. Noise is not only a nuisance but a health hazard. Noise has the power to cause tension, anxiety, and sometimes illness and when one is affected by noise after a long period then they may lose their hearing ability. Noise is even considered as an international health concern, therefore noise prevention and control are very important.
Noise mitigation and control are set of strategies that aim to reduce noise pollution or the impact of noise in any environment, whether indoors or outdoors. There are certain areas that always need noise control and mitigation; they are architectural design, transportation noise mitigation, occupational noise control and urban planning and zoning codes, aircraft, and roadway noise. There are social activities that may produce a lot of noise, which may irritate the people living in the nearby environments.
There are different mitigation measures that have put in place to be practiced to reduce noise pollution especially in the construction sites as well as other areas prone to noise pollution. Some of these mitigation measures include;
a).Land Use Planning
Ensuring the capability of different uses that are adjacent to each other is one of the ways to minimize the impact of noise pollution when planning. Outline Zoning Plans have been drawn to govern and control the uses of lands that are adjacent to each other. For example, an area that is non-noise sensitive can be placed between zones thus reducing the impact of noise, which may be coming from an industrial area some kilometers or miles away (Chen, Hill, and Sha 2016).
b.) Alternative Alignment or Sighting
The most effective method to deal with noise is simply planning the problems away by just selecting the alternative site, which avoids serious problems. If a given locality is unsuitable for development of noise sensitive use, then choosing another location is the best solution to problems that may come.
This kind of noise of mitigation measure involves building residential houses on tip of podiums to shield them from the traffic noise coming from the roads in their vicinity.
d.) Screening by Noise Tolerant Buildings
Noise tolerant buildings like a multi-storey car park can be used to protect the residential buildings from the noise that is coming from the traffic on roads. This is done by placing a nose tolerant building just between the residential buildings and the road traffic thus reducing the impact of noise on the residential buildings.
e.) Building Disposition
Proper disposition of the buildings that are noise sensitive can also reduce the impact of the environmental noise.
f.) Noise Barrier
A noise barrier will reduce the impact of noise by simply disrupting the sound waves propagation. A proper design and a good selection of the material to be used as the noise barrier will ensure the noise that reaches a noise sensitive area will be primarily only through diffraction around its ends and the top of its barrier. An effective noise barrier has the power to reduce noise to as much as 20 dB (A).
There are several types of noise barriers which have been used in Hong Kong, they include; vertical barrier, cantilever barrier, and central barrier.
Noise prevention and attenuation are very important, however, there are advantages and disadvantages that come from using these mitigation measures to reduce the impact of noise. The advantages of noise mitigation measures have increased greatly over the previous decade. They include; residential areas are more peaceful and people can live in harmony not having to deal with noise. Areas that are noise sensitive like the hospitals have become noise free and patients get a friendly environment that encourages quick recovery. An institution like schools and workplaces can hardly conduct their day to day activities when there is noise, this is taken of these days as the noise mitigation measures put in place prevent them from the impact of noise.
However, there are disadvantages that come with the noise mitigation measures that aim to reduce the impact of noise in the noise sensitive areas. Industries that always produce noise in their daily activities are forced to use expensive material that will reduce the impact of noise on the neighboring residential areas. These industries are sometimes forced to locate their businesses far away from the residential areas where the pieces of lands are expensive to buy. These industries will still have to use transportation costs to distribute their products in the residential areas. Noise mitigation measures are therefore an advantage to many people in the society but also a disadvantage to some (Alipouri & Alipour 2016).
Advantages of the Current Methods
- The methods help prevent external noise hence reduce disturbances
- The noise mitigation methods are very important for human health. For instance, they prevent hearing loss.
- They help people living near towns and industries have better sleep, study, or work without external noise (Beranek and Ver 2012).
Disadvantages of the Methods
- The noise mitigation strategies are complex thus more expensive due to the additional costs involved in the construction process
- Noise mitigation strategies are not ideal where sudden noise as gunshots or airplanes landings are present.
- The strategies used to mitigate sound do not block all the noise as some noise gets through causing a disturbance (Alipouri & Alipour 2016).
In conclusion, noise affects the normal functioning people. Some of the common effects of noise are heard loss, irritation, and general stress. The major sources of noise include public transport, airports, and trains just to mention a few. Therefore, it is imperative for noise attenuation and prevention in civil engineering in order to mitigate against ambient noise.
Alipouri, Y., & Alipour, H. 2016. Attenuating noise effect on yaw rate control of independent and variance controller. Nonlinear Dynamics, 1-15.
Beranek, L.L. and Ver, I.L., 2012. Noise and vibration control engineering-principles and applications. Noise and vibration control engineering-Principles and applications John Wiley & Sons, Inc., 814 p., 1.
Chen, J., Hill, K. and Sha, S.H., 2016. Inhibitors of Histone Deacetylases Attenuate Noise-Induced Hearing Loss. Journal of the Association for Research in Otolaryngology, 17(4), pp.289-302.
Gaudreau, M.A., Sgard, F., Laville, F. and Nélisse, H., 2017. A finite element model to improve noise reduction based attenuation measurement of earmuffs in a directional sound field. Applied Acoustics, 119, pp.66-77.