Geographical Theories, Concepts and Ideas of Noise Pollution
Of all environmental pollution, the type that receives the least attention is noise pollution or the excessive or unwanted sound. It is important to take note that noise pollution can create huge impact over the physical and emotional health of the entire community, which includes hearing loss, stress, emotional problems. Aside from these, it can also interrupt concentration, at the same time; can cause unintentional injuries (McKenzie, Pinger and Kotecki, 2005).
Noise can be classified into groups based on the sources of generation: (a) continuous wide band noise; (b) continuous narrow band noise; (c) impact/impulsive noise; (d) repetitive impact noise; (e) intermittent noise. In addition, noise sources can be further classified into 3 main categories, which include: mechanical, fluidic and electrical (Tripathy, n.d.). According to the research conducted in Central London in 1961 – 62, road traffic is the major source of noise pollution, while at home or outdoors or at work. In addition, other important noises which disturb people are: aircraft, trains, industry/construction work, domestic appliances, neighbors’ impact, children, adult voices, radio/TV, and bells/alarms (Discovery.Bits, n.d.).
Sound is head when energy from vibration travelling via air, liquid or even solid media as pressure waves is received by the ear. Noise pertains on unwanted and unpleasant sound. But, what constitutes unwanted sound is considered as a matter of subjective judgment. As a result, noise is being measured by an annoyance factor. Amplitude pertains on the sound volume – the loudness and intensity of sound. Amplitude is being measured and expressed as decibels (dB). The decibel scale, which is logarithmic in nature, ranges from 0dB or the threshold of hearing, up to 180 dB, which is the sound of a rocket engine. As a result, a sound measured at 10 dB is 10 times louder than 0 dB and 20 dB is 100 times louder than 0 dB. There are 3 standardized weightings used: A, B and C. Federal regulations use A network in measuring the sound in the settings of environmental and occupational settings (McKenzie, Pinger and Kotecki, 2005).
There are different instruments that are used in order to measure noise. Noise measurements are considered as vital diagnostic tools in noise control technology. The main objective of noise measurement is to make an accurate measure which will enable the government and the entire society to act of comparing noises under different conditions of assessment of adverse impact of noise as well as the adaptation of appropriate control techniques in order to reduce noise.
There are 6 common measurements of noise levels: sound level meter, impulse meters, frequency analyzers; graphic recorders; noise dosimeters and calibrators. The table below shows the specification or area of usage of these measurements.
Equipment
Specification/Area of Usage
Sound level meter
Type-0: laboratory reference standard
Type-1: lab use and field use in specified controlled environment
Type-2: general field use (Commonly used)
Type-3: Noise survey
Impulse meters
For measurement of impulse noise levels, such as hammer blows, punch press strokes etc.
Frequency analyzers
For detailed design and engineering purpose using a set of filters.
Graphic recorders
Attached to sound level meter. Plots the SPL as function of time on a moving paper chart.
Noise dosimeters
Used to find out the noise levels in a working environment. Attached to the worker.
Calibrators
For checking the accuracy of sound level meters.
Source: (Industrial Safety and Control Handbook, 1991)
A sound level meter is consists fundamentally of a microphone and an electronic circuit which include an attenuator, amplifier, weighting networks or filters and a display unit. The microphone translates the sound signal to a matching electrical signal. Then, the signal will be passed in a weighting network which will offer a conversion and enable the sound pressure level in dB. The instructions given by the noise level meter manufacturers will be followed while using the instruments.
The time constants used for the sound level meters are:
S (Slow) = 1 second
F (Fast) = 125 milli seconds
Comparatively, steady sounds are easily measured by using the fast response, while the unsteady sound can be measured with the use of the slow response. In the process of measuring the long-term noise exposure, it is important to take note that the noise level is not always steady and may change in considerable manner, in irregular way over the period or duration of the measurement. As a result, in order to solve this uncertainty, it is important to measure the continuous equivalent level, which is commonly defined as the steady pressure level of sound which would have produced the same total energy as the actual level over the specific time (Discover.Bits, n.d.).
References
Discover.Bits. Noise pollution and its control. Retrieved 11th November, 2010, from discover.bits-pilani.ac.in/dlpd/courses/coursecontent/courseMaterial\etzc362\Noise_Pollution_notes.pdf
Industrial Safety and Pollution Control Handbook (1991). Associate Publishers Pvt.
McKenzie, J., Pinger, R. R. and Kotecki, J. E. (2005). An introduction to community health. Jones & Bartlett Learning.
Tripathy, D. P. Noise pollution. APH Publishing.
Credit:ivythesis.typepad.com
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