UTHM Conference Portal, International Conference on Mechanical and Manufacturing Engineering (ICME2015)

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Research Finding in Natural Fibers Sound Absorbing Material
Mohd Nor Azmi Bin Ahmad Nordin

Last modified: 2015-10-08

Abstract


In simple terms, noise is unwanted sound. Sound is a form of energy which is emitted by a vibrating body and on reaching the ear causes the sensation of hearing through nerves. Sounds produced by all vibrating bodies are not audible. The frequency limits of audibility are from 20 HZ to 20,000 HZ. Excessive levels of sound can cause permanent hearing loss while continuous exposure could be physiologically and psychologically deleterious to one’s well-being. Nowadays much importance is given to the acoustical environment. Noise control and its principles play an important role in creating an acoustically pleasing environment. This can be achieved when the intensity of sound is brought down to a level that is not harmful to human ears. Achieving a pleasing environment can be obtained by using various techniques that employ different materials. One such technique is by absorbing the sound. This paper review and describes how the physical prosperities of materials like fiber size, material thickness, density, porosity and tortuosity can change the absorption behavior. The sound absorption of different natural fibers was experimentally tested. The results show the relationship between natural fibers like kenaf, bamboo, paddy and the sound absorption, material density, thickness and air gap. Higher airflow resistance always gives better sound absorption values but for airflow resistance higher than 1000 the sound absorption have less values because difficulty movements of sound wave through the materials. More fibers can create more tortuous path (increase tortuosity) and can also increase the flow resistivity. However, by further increasing the density (adding more fibers), close pores could be formed and thus greatly increase the flow resistivity and eventually reduce the absorption capability.


Keywords


Natural fibers