Noise Pollution Control Research Articles

Extent of Traffic Induced Noise in the Noise Sensitive Institutions of Chittagong City, Bangladesh

In this study, we have investigated the amplitude and intensity of traffic induced noise at noise sensitive institutions of Chittagong city in Bangladesh. The study has been conducted covering four types of sensitive institutions (for instance: schools, colleges and hospitals) from each of the three deliberately selected wards (administrative areas) out of 41 wards of the city. Maximum and minimum sound levels in all the sensitive institutions in average ranged from 65.84 to 79.69 dB and 59.73 to 69.03 dB respectively. In all the 12 different sensitive institutions, noise has exceeded the safe limit (45 dB) as set for noise sensitive institutions such as schools, colleges, hospital, parks by the Department of Environment (DoE), Bangladesh and World Health Organization (WHO). In all the three wards, sound level reached the maximum between 11am and 1pm, both at entrance, in the premises and inside the rooms. Sound levels showed a significant ( P=0.000) declining trend with increase in the distance from the source of noise. The majority of the respondents (73%) have indicated vehicular noise as the main source of noise in their institutes. Buses (29%), Private Cars (27%), Trucks (21%) and Three Wheeler Auto Rickshaws (14%) have been given as the major sources of traffic noise by the respondents. Adverse impacts of traffic induced noise on people inside the sensitive institutions (students in the classroom, and patients, nurses, doctors in the hospitals) have been divided into three categories physical health problems, mental health problems and other noise related problems. Among noise induced physical health problems – headache (79%), and among mental health problems – impaired concentration (82%) have been pointed out by the maximum number of respondents. Moreover, among all other noise induced problems, interference in communication (81%) has been reported as the highest one. The findings of the present study can be considered as baseline data for the decision makers in formulating policies and guidelines regarding the control of noise pollution in context of noise sensitive institutions.

Exposure of educational institutions to traffic-induced noise at Chittagong City, Bangladesh

The amplitude and intensity of traffic-induced noise at the environmental setup of the educational institutions in Chittagong City, Bangladesh were investigated. Average maximum and minimum sound levels in the study area ranged from 65.46 to 82.24 dB and 60.63 to 70.89 dB, respectively. Noise at all the studied educational institutions exceeded the safe limit (45 dB) as prescribed by the Department of Environment, Bangladesh and World Health Organization. Sound levels showed a significant (P = 0.000) declining trend with increase in the distance from the source of noise. Among the noise-induced physical health problems, headache (69%) and among the mental health problems, lack of concentration in study (78%) was expressed by the maximum number of students. The findings of the study can be considered as baseline data for the decision makers in formulating policies and guidelines regarding the control of noise pollution in the context of educational institutions.

Urban and building acoustics management in the next decades: a matter of prevention, simplification and education

In Brazil, in cities like Sao Paulo and Rio de Janeiro, noise pollution control has been carried out mainly in the form of repression. In the seventies and eighties, people joined together to fight against noisy government projects, and government fought noisy industries and commercial establishments. Since then, people have become aware of their rights, but have learned little about their own obligations on the matter. The author researched this process in order to find a better way for the future and concluded that prevention must be enforced through noise codes, standards must include easier survey methods, and low cost devices for noise control must be available. Most important, education must be improved in all levels, to make every citizen a partner of noise control at home, at work and elsewhere in the cities. This paper points out some ways of dealing with this process.

A noise mapping study of a large metropolitan city with a heterogeneous traffic

Traffic noise characteristics in some of the cities in a developing country like India are slightly varied by virtue of the fact that the composition of the traffic is heterogeneous accompanied by variance in road geometry and varying density of the buildings on the either side of the road. To study the feasibility of noise reduction in some of the areas a noise mapping study has been attempted along with field measurements of L10, L50, L90 and Leq. In the noise mapping parameters such as Ld, LN, Lden have been arrived at by taking into consideration the geometrical features of the roads and varying heights of the buildings. In this study noise mapping through computer simulation model (soundplan) is used by considering several noise sources and propagation of noise to the receiver point. This paper describes how the local characteristics of the city affect the propagation of noise and describes an integrated approach to control noise pollution in these areas. A three dimensional acoustical model has been developed for two locations of the city. Methodologies of noise control through noise contours around traffic are illustrated.

Analytical and Experimental Study on Noise Attenuation of Multi-Cylinder Diesel Engine with Existing and Modified Muffler

Man's desire for a pollution free atmosphere entails control of air pollution and noise pollution. The principal sources of noise in automotive engines are intake noise, radiator noise, combustion noise, exhaust noise etc. Out of these, exhaust noise is predominant and has to be controlled. Noise pollution affects human beings physiologically and psychologically. In this paper on reactive muffler for a multi-cylinder diesel engine is designed and modified. More attenuation is given by making some changes in its configuration. The Bond graph technique has been applied for the analytical results of the muffler. The modelling of acoustic and other systems are easily and logically achieved through Bond graph technique[1,2,3]. Bond graph, invented by Paynter, is a method or representation of a physical system by means of symbols and lines, identifying power flow paths and lumped parameter elements of resistance, capacitance and inductance. The Bond graph model is created by taking wave propagation in acoustic material into consideration. The analysis of the Bond Graph model was carried out by using software COSMO-KGP. These results were compared with the experimental results and found to be in close agreement.

Study on the effect of porous fence on air quality and traffic noise level around a double-decked road structure

Fence for traffic noise control sometimes causes adverse effect on air pollution. Thus in this study, performance of porous fence as a tool for control of both air pollution and noise pollution was evaluated. A two-dimensional numerical model for flow and pollutant concentration and an analytical model for traffic noise were utilized in the analysis of a double-decked road structure with fences only at ground (Case 1) and at both ground and upper deck (Case 2). Porous fences were assumed only at the ground level since the solid fences at the upper deck usually leads to desirable result on air pollution. Effects of the variable porosity on air quality and noise level near road were evaluated. Obtained results showed: (1) flow pattern in leeward of fence was drastically changed at 40-50% porosity in Case 1 and 50% in Case 2. The porosity larger than 40% excluded presence of a circulation behind the fence. (2) Effect of porous fence on air pollution was different in Cases 1 and 2. In Case 1, the porous fence generally resulted in the reduction of air pollution at the ground level; on the other hand, in Case 2, it rather led to increase of the concentration. (3) Traffic noise level was also largely changed by the porosity of the fence; an example of simultaneous evaluation of the effects of porous fence on both air and noise pollution in Case 1 showed that the fence of 60% porosity leads to reduction of air pollution by 20% compared with solid fence case, and reduction of noise pollution by 4-6% in dB compared with no fence case, at 1 m high and 10 m from the road.

The Study of Noise Pollution in Weaving & Textile Industries in Kermanshah (2001)

Introduction: Noise is one of the hazardous factors in work places such as textile industries. The objective of this study is to determine noise pollution in textile industries in Kermanshah (2001). Materials & Methods: This study is an analytical-descriptive one. The study was done in 2 steps. In the first step the characteristics of the work place & buildings were completely determined; then according to the method of ISO & NOISH; the buildings were divided in 2*2 squares and the level of sound pressure was measured. The noise was analyzed and the SIL factor was calculated by using the results. In the second step, by using a chronometer, time was measured, job analysis was done and the Leq factor was measured. The results were compared with the standard by using Z statistical method. Results: The results showed that the level of noise was 93.44±3.28 db, which was higher than the standard (P<0.05). This study also showed that the level of pressure of noise was high in frequencies of 500–4000 HZ. The level of speech interference in these industrial group was 78.51±2.3 and that of Leq was 87.9±3.23 which showed that the Leq factor was higher than the standard (P<0.05). Conclusion: According to the above results we can conclude that controlling noise pollution in textile industries is very important. The spectrum of noise showed that the level of interference of sound was high.

Traffic noise attenuation by scattering, resonance and dispersion

The purpose of this investigation is to analyze various techniques of sound attenuation which can be used to minimize traffic noise from heavy traffic circulation in urban areas, and to improve sound quality in these areas using selective absorption in specific frequency ranges, plus to reduce the degree of annoyance of traffic noise. This study covers uncontrollable noise sources such as trucks, automobiles and trains, in heavy traffic urban areas. Different methods of noise energy reduction are discussed, including sound attenuation by selective absorption, scattering and cavity resonance in the sound barriers. Multiple scattering on sound absorbing road and barriers are considered to increase noise energy dissipation in unwanted frequency ranges. The effects of dispersion and change in the frequency content of the noise with distance are studied. An elimination of the most disturbing frequency components of these uncontrollable noise sources improves sound quality from these sources and increases our overall capabilities in controlling noise pollution in the urban environment.

Acoustic properties of rubber crumbs

The purpose of this article is to demonstrate that in the actual state of the art, recycled rubber products can be used to form acoustic absorbent materials, applicable to control noise pollution. Their applicability in noise screens shows excellent performance of broadband acoustic absorption. The article summarises part of a recent research carried out in the `Instituto de Acústica (CSIC)', that has concluded in a Spanish and EU patent about absorbing noise screens [1].

Development of a muffler for control of noise pollution in a diesel engine

The present work aims at controlling the noise level of a diesel engine by developing an exhaust muffler for the same, since exhaust noise is the single largest contributor to the overall noise from the engine. The TATA 1210 six-cylinder diesel engine was considered for test purposes. A simulated design, developed by Ricardo with the application of the engine performance simulation program WAVE, was taken up, and this was modified in certain aspects to suit the engine under consideration. The muffler was fabricated and data were recorded for evaluation of the acoustic performance as well as the engine performance and for purposes of comparison with the existing muffler as well as with the open-ended exhaust system. The new muffler was found to be superior to the existing one in terms of both acoustic performance and engine performance. With the new muffler, the maximum noise reduction obtained was 19.3 dB(A) and the maximum brake thermal efficiency obtained was 39 per cent, while with the existing muffler the corresponding values were 14.5 dB(A)and 37.4 per cent. The present work has thus experimentally shown that results from WAVE can be modified and applied to an alternative design.

The degradation of doppler sodar performance due to noise: a review

Ambient background noise is a common problem for poor Doppler sodar performance. This noise can be active or passive and broad-band or narrow-band. Active broad-band noise decreases the sounding range of the sodar by decreasing the signal-to-noise ratio. Active narrow-band noise can be interpreted as erroneous wind values. Passive noise sources are objects which reflect the transmitted acoustic pulse back to the sodar with zero Doppler shift. Use of acoustic shielding is discussed as a method of noise pollution control by isolating the side lobe energy of the transmitted acoustic pulse. At the same time, these acoustic shields are effective in blocking out active ambient background noise. Previous studies which experienced noise interference are shown as examples of problems that are frequently encountered.

Future large aircraft design — the delta with suction

AbstractSince the 1970s, large passenger aircraft design has evolved by modest, but commercially significant, incremental change following the underwing pod concept pioneered by the Boeing 707. In the 21st century, the market is likely to require greater passenger capacity to deal with air-side congestion and higher performance and operational efficiency to justify investment and conserve finite fossil fuel resources. Public opinion will require far greater emphasis on control of noise and engine exhaust pollution. There is likely to be much increased emphasis on pollution in the upper-atmosphere and its environmental impact. In such a situation, it is questionable whether the evolutionary design route can produce the necessary advances and this must stimulate the search for radical design alternatives.A revolutionary approach, involving the delta planform combined with wing laminar flow control and its impact on overall design, is given a preliminary study in this paper. This has been carried out by assuming that major improvements in drag can be obtained by extensive laminarisation. Using non-dimensional methods, the resulting broad interactive impacts on airframe and engine design and performance are derived. The effect of assuming varying quantities of low-energy air sucked from the foot of the boundary layer is studied and suction-system performance examined.In addition to the large potential improvements in range, a strong relationship between lower drag, lower cruising altitude and lower cruise engine size is identified. In the study, several factors emerge which may combine to drive large aircraft design towards low aspect ratio and the integrated delta wing planform. This paper is intended as a stimulus and a basis for further study and research.

Characteristics of pin and wire corona devices for electrostatic charging

The phenomenon of corona discharge is of great importance in many areas such as electrophotography, charge transport experiments, power loss on high voltage transmission lines, electrical noise and air pollution control. The construction and performance of pin and wire corona devices are discussed. Experimental results will be presented to show that the DC characteristics of the corona depend on the corona emitter, the geometry of the corona housing, the polarity and magnitude of the potential applied to the corona emitter and the spacing between the corona emitter and the detecting electrode. Corona current distribution curves clearly illustrate that wire coronas are more suitable for electrostatic charging.

The Use of High Court Injunctions to Control Noise Pollution

The Use of High Court Injunctions to Control Noise Pollution

The Existing State of Noise Pollution Control

The Existing State of Noise Pollution Control

Report on environmental noise in Ontario with reference to health related effects

The Noise Pollution Control Section, Ontario Ministry of the Environment, has received a new report on environmental noise in Ontario with reference to health related effects.

Road Noise and Property Values: Some Evidence from the Copenhagen Area

Noise has become a major problem in most industrial countries, and the costs of noise control can be expected to rise markedly in the years ahead. Consequently, the question of the optimal noise pollution control level is becoming increasingly important. In this connection, the use of property value studies has been discussed intensely. This discussion has recently been summarized in two reports from the OECD, one by Miler & Wyzga (1976) and the other by Pearce (1976). The intention here is not to review this debate once again, but rather to present some empirical evidence from the Copenhagen area on the relation between road noise and property values.

Hearings focus on controlling noise pollution

Hearings focus on controlling noise pollution

State standards, regulations, and responsibilities in noise pollution control.

In the near future the State of Minnesota will adopt noise pollution standards and regulations based on the findings presented in this paper. Comprehensive noise standards are presented for all sources of noise, including airports, highways, and industrial sources. Two of the three dimensions of noise—intensity and frequency—are measured by the use of the unit dBA, whereas the third dimension—duration—is measured by use of the temporal distribution, expressed as Lx, where x is the sound pressure level in dBA exceeded x% of the time. Standards are established for five zones: 1. residential—single family, 2. residential— apartments, public buildings, 3. commercial, 4. manufacturing, and 5 industrial. The Lx standards apply to most noises including industrial and highway noises. Aircraft noise and impulse noise standards are also discussed. The six phase implementation plan for noise abatement is discussed.

Illinois Noise Pollution Control Regulations

The recently adopted Illinois Noise Pollution Control Regulations will control noises emitted from “property-line-noise-sources,” e.g., industrial facilities, business, and commercial establishments, etc. The comprehensive regulations contain two parts: the first part contains a “nuisance” provision, and the second part contains octave-band sound pressure level limits for property-line noise sources. For purposes of these regulations, land is classified into three categories according to use, which correspond to industrial, commercial, and residential uses. The numerical limits, which will apply to a given facility, are dependent upon the land usage of both the noise emitter and noise receiver. Impulsive sounds are regulated by A -weighted sound levels, while “prominent discreet tones” are regulated in terms of 1/3-octave-band sound pressure levels. More stringent nighttime limits will apply to new facilities which emit sounds to residential lands. Compliance times for existing noise sources range from one to three years, while new facilities must comply immediately. These regulations are the first step in a program designed to reduce noise pollution in Illinois-future regulations will control noises emitted from transportation sources and construction sources.