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Noise is defined as an unpleasant sound that causes discomfort. Most of the noise that
one hears originates from human activities. The main sources of noise are: transport
sector, industrial and construction machinery and special events. Noise pollution is increasing
in the industrial societies and cities. India has emerged as a fast developing nation resulting
in rapid industrialization and urbanization. An increasing number of vehicles and
electronic devices created a serious threat of noise pollution
(May and Osman, 1980; Kumar and Jain, 1994; and Piccolo et al., 2005). Though Sangamner city has little industrialization, a
substantial volume of traffic exists due to the National highway which passes through it. This
traffic is the most important source of noise pollution in Sangamner. Noise can cause
auditory, non-auditory and physiological disorders in human beings, and can cause serious
damage to wildlife, especially in remote areas (Singh et al., 1982; Staples, 1996; Kazi, 2002;
and Lusk et al., 2002). Human ear is more sensitive between the frequency range of
2 kHz to 4 kHz. At about 300 Hz, painful sensation reaches its peak. Absorption
coefficient is different for different materials and varies with varying frequencies. There are
different types of materials which are considered as absorptive material. Producing less noise is
the best method of reducing pollution. Another way is to provide shields of noise
absorbing material. Plants and trees absorb and dissipate sound energy and act as buffer zone,
reducing the noise up to 5 to 10 dB. Leaves absorb acoustic energy by transferring the kinetic
energy of the vibrating air molecule in a sound field to the vibration pattern of the leaves.
Therefore, vibration energy is withdrawn from the acoustic field and a part of this energy is lost as
heat. A number of researchers have proved that wood and leaves of plants and trees serve as
good absorptive materials (Santosh and Tripathi, 2008). Therefore, plantation of trees and
plants should be done along highways and residential areas, offices, schools, colleges,
industrial area and public places. Noise pollution in Sangamner city at different places and
sound absorption coefficient were studied using different types of wood samples as noise
absorbers. The absorption coefficient determines the extent to which a particular type of tree or
plant can reduce noise. This helps to select plants and trees suitable for plantation.
For the study, first the sources of noise pollution are detected by surveying the complete
city. These sources are divided into six areas or sources: (1) Transport; (2) commercial area;
(3) silence area; (4) electrical devices; (5) undefined areas; and (6) special event. The
noise level of each source and at each place is measured in dB using the Sound Level Meter
(SLM) at a time interval of 5 m. The measured values were compared with the permissible
noise level values recommended by the Central Pollution Control Board (CPCB) and are
presented in Tables 1(a) to 1(f). The CPCB recommended 45 dB as safe level, up to 65 dB, the
level is tolerable. Noise beyond 80 dB impairs hearing. |
