Acoustic Behaviour of Nonwovens

Abstract

Influence of Fibre Cross Section and Various Bonding Techniques Adopting TaguchiOwing to their high porosity and low solid volume fraction nonwoven materials are considered to be the most appropriate textile based sound absorbers for noise control applications. The solid volume fraction in majority of nonwovens could be 20% or less. The structure of nonwovens inherently has pores with tortuous paths, allowing the sound waves to enter through them. Various kinds of pores like 'open' or 'closed' can be present in a porous material [6]. 'Open' pored materials have a continuous channel of communication with the external surface of the body.The open-pored structure of nonwovens provides a proper medium for sound waves to be absorbed by three mechanisms which are: converting the sound energy into heat in the material, viscous losses because of the oscillating air flow entering the porous areas inside the material and vibration of fibers due to vibration of air particles caused by the sound waves [7]. Since nonwoven materials have a complex structure, there are many variables influencing