The wool Handbook, Chapter 21

The wool Handbook, Chapter 21



Publisher : Woodhead Publishing-Elsevier
ISBN : 9780323995993
Pages : 3
Status : Printed
Price : IRR 500
Noise pollution is known as a serious environmental problem in today’s modern cities. Excessive noise exposure may have harmful effects on human health. Moreover, extra noise in the working environment can reduce productivity and work efficiency and impact job satisfaction. Noise is also a major problem in transportation, can lead to driver fatigue, and risks occupant safety Using sound-absorbing or acoustic materials is an efficient approach to reduce and control the environmental noise. These materials can effectively absorb part of the incident sound energyIn order to achieve effective sound absorption, porous materials are great candidates. The pores and void spaces effectively boost sound wave penetration into their structure [610]. Fibrous matrices are excellent porous materials used for sound absorption. Recently, with the development of society, fibrous structures are widely suggested as economical and efficient acoustic absorption materials for sound reduction and vibration control [8,9,11,12]. Sound absorption function can be determined by absorption coefficient, reflection coefficient, and acoustic impedance. The acoustic properties of fibrous materials are commonly described by measuring the noise absorption coefficient [8,12,13]. Acoustic fibrous materials, in the form of nonwovens, knitted or woven fabrics, foams, and carpets, are utilized for insulation aims in construction, and automotive industries as well as in indoor spaces [2,6,12]. The acoustic behavior of textile insulators can be described by several parameters, and each one often needs a specific model [1]. Fiber type is the important parameter that affects the sound absorption characteristics of a fibrous material. The fibrous acoustic absorbers are manufactured with a natural, synthetic, or combined content. The investigations performed on natural fibers have demonstrated that, as same as the conventional porous materials, these fibers exhibit proper sound absorption coefficients, particularly at medium and high frequencies [7,9,12]. Sheep wool is one of thebeneficial natural fibers that has been considered since ancient times owing to its superior insulation features. Due to the coiled springs of molecular chains and their microcavities, wool fibers act as very effective sound absorbers
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