Design of enclosure of a grinding machine for the noise attenuation.

Since most of the equipments are usually installed in rooms or enclosed plants, the effect of an enclosure is important. Absorptive surface of the enclosure can reduce levels to the extent of 5 dB(A) which is quite significant. Effectiveness of enclosures in sound varies with the frequency of sound and the shape, size, laying pattern of sound absorbing material, which is put on the walls of the enclosure. The sound absorbing material accomplishes little shielding if there is no acoustical absorption within it. Acoustical absorbents when applied to the interior surface of the enclosure adsorb some of the energy and the noise level within the enclosure builds up only by the energy not absorbed. This paper elucidates the procedure of developing an enclosure to study its performance in attenuating sound at varying conditions. The results found encouraging and such enclosures can be developed for plant machineries by the plant personnels without getting confused by the claims and rhetoric of advertisements of big companies engaged in developing such items.

Noise and its effect on human being--a review.

Noise pollution, as it affects human being, has been a recognised problem for decades in the developed countries, but it is still ignored in the developing and underdeveloped countries. Effects of noise on human beings often presents conflicting results because of the variety of factors and variables that can effect and/or interfere with the determination of the actual effects. This is because the response of the people vary place-to-place, situation-to-situation for the same noise level. This subjective response has been quantified by various researchers and indicated with different indices. This paper highlights the research carried out by different scientists across the world on the harmful effects of noise on human being.