A. R. MOHANTY and S. FATIMA

6.1 INTRODUCTION

With growing concerns towards the environment, designers are looking forward to the use of environmental friendly materials for product development. Though the aim is not to replace completely the metals or synthetic materials by these environ­ment friendly materials. For the former have high strength and long life. However in few applications the use of composites made up of a combination of natural fiber based materials and a binder have many advantages. Like they are environmental friendly, less weight, economical and in few places are also available abundantly in nature. Natural based fiber materials like flax, ramie, hemp, banana fiber, coir, jute, cotton can be used to produce biocomposites which have many industrial ap­plications. These biocomposites are being used to manufacture machinery enclo­sures, furniture, highway crash barriers, geo-textiles, as reinforcement in concrete, apparels, bags, yarns, carpets and building materials. However, they have a strong potential to be used for noise control applications as well.

Human beings are uncomfortable at exposure to high sound levels for a long duration. Such undesired sound are known as noise. Thus designers of machines, building architects, city planners, automobile designers and environmentalist have to take due consideration in design of machines, building, city planning and so forth, so that the human being is comfortable in the respective situations. Moreover due to stiff global competition among manufacturers, everyone is striving to make their products quieter than the other. Keeping the above in consideration, this chapter introduces to the basics of sound along with the associated terminology. Then it fo­cuses on the physical, mechanical, thermal and acoustical properties of such materi­als. Followed by a description of their use in various applications like architectural acoustics, home appliances, machinery enclosure and automobiles for noise control.