Thesis noise pollution
Road traffic noise and public health effects
Both temporary and permanent components of hearing threshold shift are possible Matthews, Noise is unwanted electrical or electromagnetic energy that degrades the quality of signals and data. Noise occurs in digital and analog systems, and can affect files and communications of all types, including text, programs, images, audio, and telemetry. In a hard-wired circuit such as a telephone-line-based Internet hookup, external noise is picked up from appliances in the vicinity, from electrical transformers, from the atmosphere, and even from outer space.
Normally this noise is of little or no consequence. However, during severe thunderstorms, or in locations were many electrical appliances are in use, external noise can affect communications. In an Internet hookup it slows down the data transfer rate, because the system must adjust its speed to match conditions on the line.
In a voice telephone conversation, noise rarely sounds like anything other than a faint hissing or rushing. Noise is a more significant problem in wireless systems than in hard-wired systems. In general, noise originating from outside the system is inversely proportional to the frequency, and directly proportional to the wavelength. At a low frequency such as kHz, atmospheric and electrical noise are much more severe than at a high frequency like megahertz.
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Noise generated inside wireless receivers, known as internal noise, is less dependent on frequency. Engineers are more concerned about internal noise at high frequencies than at low frequencies, because the less external noise there is, the more significant the internal noise becomes.
Communications engineers are constantly striving to develop better ways to deal with noise. The traditional method has been to minimize the signal bandwidth to the greatest possible extent. The less spectrum space a signal occupies, the less noise is passed through the receiving circuitry. However, reducing the bandwidth limits the maximum speed of the data that can be delivered. Another, more recently developed scheme for minimizing the effects of noise is called digital signal processing digital signal processing.
Using fiber optics, a technology far less susceptible to noise, is another approach Techtarget, Noise Pollution generally refers to unwanted sound produced by human activities unwanted in that it interferes with communication, work, rest, recreation, or sleep. Unlike other forms of pollution, such as air, water, and hazardous materials, noise does not remain long in the environment.
However, while its effects are immediate in terms of annoyance, they are cumulative in terms of temporary or permanent hearing loss. Society has attempted to regulate noise since the early days of the Romans, who by decree prohibited the movement of chariots in the streets at night. In the United States, communities since colonial days have enacted ordinances against excessive noise, primarily in response to complaints from residents. It was not until the late s, however, that the federal government officially recognized noise as a pollutant and began to support noise research and regulation.
Federal laws against noise pollution included the National Environmental Policy Act of , especially sections concerning environmental impact statements; the Noise Pollution and Abatement Act of ; and the Noise Control Act of , which appointed the Environmental Protection Agency EPA to coordinate federal research and activities in noise control. Charged with developing federal noise-emission standards, identifying major sources of noise, and determining appropriate noise levels that would not infringe on public health and welfare, the EPA produced its so-called Levels Document, now the standard reference in the field of environmental noise assessment.
In the document, the EPA established an equivalent sound level Leq and a day—night equivalent level Ldn as measures and descriptors for noise exposure. Soon thereafter, most federal agencies adopted either the Leq, Ldn, or both, including levels compatible with different land uses. The Federal Aviation Administration FAA uses Ldn as the noise descriptor in assessing land-use compatibility with various levels of aircraft noise.
In the research findings of Theodore J. Schultz provided support for Ldn as the descriptor for environmental noise. Analyzing social surveys, Schultz found a correlation between Ldn and people who were highly annoyed by noise in their neighborhoods. The Schultz curve, expressing this correlation, became a basis for noise standards. As part of its effort to identify major noise sources in the United States, the EPA set about determining the degree to which noise standards could contribute to noise reduction.
During the s, EPA-sponsored research on major noise sources led to regulation of the products that most affected the public, including medium and heavy trucks, portable air compressors, garbage trucks, buses, and motorcycles. Missing from the list was aircraft, which was considered the responsibility of the FAA. During the administration of President Ronald Reagan in the s, the power of the EPA and its Office of Noise Abatement and Control was curtailed and most of its noise regulations rescinded. Even so, efforts continued to curb noise pollution. The Department of Transportation maintains standards for highways, mass transit, and railroads, as well as aircraft.
The environmental review process, mandated by the National Environmental Policy Act of , remains the single most effective deterrent to noise pollution Answer, Noise can increase the overall workload of operators during a specific task and can affect the performance. Exposure to intense noise has been shown to damage the human hearing process and noise has been labeled as the most pervasive hazardous agent in the workplace Milz et al. According to McBride et.
The reduction in the hearing loss does not decrease below Hz Akyildiz, It was showed that noise induced hearing loss increase up to 7dB in the first 10 years at Hz and dB A , and then gradually increases to 12 dB losses for exposure time of 40 years. The hearing loss is about 30 dB for first ten years exposure at Hz and dB A. It is clear that at dB A , the ear is much more sensitive to Hz compared to Hz.
At levels lower than this value, the risk of noise becomes the least Grandjean, This particular pattern of appears regardless of the noise exposure environment. Therefore it is crucial to keep sound pressure levels within safety limits to avoid health related disturbances and work related inefficiencies. Sanders and McCormick explained that the ear is more sensitive to noise at frequencies over Hz and the sensitivity increase with age.
Miyakita and Ueda wanted to determine the number of persons exposed to loss of hearing at levels above 40 dB at a frequency of 4 Hz; and as a result, estimated that , people working in agricultural facilities in Japan impaired their hearing abilities. This feature makes the agriculture their second biggest sector after the construction sector, which causes the loss of hearing abilities. Exposure to occupational noise has been linked to variety of physical effects such as work absenteeism and stress.
The most profound effect of prolonged exposure to noise is the noise induced hearing loss NIHL.
NIHL is an irreversible sensory-neural hearing impairment caused by prolonged exposure to noise. NIHL causes communication interference that can substantially affect social integration and the quality of life. The development of NIHL depends on exposure time, intensity, frequency, type of noise, and the use of personal protective equipment Ismail et al, unpublished. Noise-induced hearing loss NIHL is a well and long recognized occupational hazard but methods of influencing attitudes towards noise hazard and prevention of hearing loss as a result a poor World Health Organization, Although the effects of noise on hearing are not precisely defined and uncertainties remain, there is sufficient information to permit development of predictive indices of the hazardous effects of noise on human hearing sensitivity.
Noise Pollution: Free Cause and Effect Essay Samples and Examples
The effects of noise on hearing may be divided into three categories which are acoustic trauma, noise-induced temporary threshold shift NITTS and noise-induced permanent threshold shift NIPTS. Acoustic Trauma immediate organic damage to the ear from excessive sound energy is restricted to the effects of a single exposure or relatively few exposures at high sound levels. Extremely intense sound reaching the structures in the inner ear may exceed the physiologic limits of those structures producing a complete breakdown and disruption of the organ of Corti.
Some degree of permanent hearing loss usually results from acoustic trauma. The precipitating episode is frequently dramatic so the person involved has no difficulty in specifying the onset of the resulting hearing problem. Noise-Induced Temporary Threshold Shift NITTS results in an elevation of hearing levels such as loss of hearing sensitivity, following shift the hearing loss is reversible. There is no possibility of further recovery. Permanent threshold shift may result from acoustic trauma or may be produced by the cumulative effect of repeated noise exposure over periods of many years.
The majority of those persons experiencing permanent hearing losses from noise sustain such losses from long periods of repeated noise exposure. Hearing ability decreases as age progresses. Age has been identified as one of the individual risk factors for sensory neural hearing loss SNHL among forest workers who handled chainsaws. Hearing loss induced among elderly miners in Romania was more pronounced compared to younger miners. Age is positively associated to hearing loss among metal processing factory workers in Brazil, with prevalence ratio of 4.
Workers exposed to chemicals have significantly poorer pure-tone thresholds compare to those not expose Morata et al. Lonsbury and Martin gave audiogram results that show audiometric patterns of hearing levels from patients in beginning stages of noise induced hearing loss and examples were given for males and females exposed to noise in different environments including industrial noise.
Hearing loss was not observed at frequencies below Hz and was sharpest above Hz for a male industrial worker. Patients working in different sectors showed that the hearing loss might not be observed below Hz in different work environments while others might experience hearing loss at about Hz. The sensitivity is also affected by gender and the number of years worked in a particular environment. A-weighted equivalent sound pressure level of 85 dBA results in temporary hearing losses and 90 dBA increases the blood pressure, accelerates the pulse and breathing, decreases brain liquid pressure, causes tension in muscles, and withdrawal of blood in the skin Sabanci and Uz, Lonsbury and Martin gave audiogram results that show audiometric patterns of hearing levels from patients in beginning stages of noise induced hearing loss and examples were given for males and females exposed to noise in different environment including industrial noise.
Hearing loss was not observed at frequencies below Hz and was the sharpest above Hz for male industrial worker. According to Dewangan et al. High noise levels can cause headaches; dizziness; nervousness and stress; sleeping problems; and loss of concentration.
Noise can also increase human error, contributing to accidents by masking audible alarms, verbal messages, etc.