ABSTRACT

There is a large number of noisy equipment requiring arrangement of soundproof enclosures to limit the spread of noise in modern civil and industrial buildings. Noise reduction is due to the noise source enclosure designs with high sound insulation. At that a part of the sound energy penetrates through the insulating enclosure housing, a variety of leaks and holes and is radiated into the surrounding air space. Thus housing becomes a source of noise. When selecting and designing the soundproof housing assemblages one must carry out assessment of the sound energy spread from them as from secondary sources of noise. The method of calculation of the direct sound pressure levels emitted by the covers is considered in the paper, taking into account the characteristics that affect the distribution of the sound energy in the environment. The easier casing shape as compared to equipment form, stability and predictability of the noise emission factors of its elements allow to apply more accurate methods for calculating the levels of direct sound in its near field. In an attempt to reduce sound radiated from a portable generator, a sound proof enclosure has been developed to absorb effectively the generator noise. This sound proof enclosure is designed and fabricated with locally available materials from the opinion of an idea which aims at easing the pains and stress of receiving the noise radiating from a portable electric generating set. The walls of the enclosure is fabricated by combining panels of foam, composite sawdust and grinded glass and an outer plywood with air trapped in-between the composite and plywood. A reverberation room method is used to measure the noise absorption efficiency of the enclosure using a 950 watts/220 volts rated generator to ascertain the enclosure performance average at 76.40% noise absorption. In view of this, this paper reports the development of soundproof device for 950Watt rated generators which are widely used portable generators. Performance evaluation of the soundproof device was carried out, and the sound pressure level of the generator was reduced by 7.64, 6.24, 6.82, 8.72 and 8.68dB at distances of 0.70, 1.40, 2.10, 2.80 and 3.50m from the generator respectively.