Measuring Methods of Acoustic Properties and Influence of Physical Parameters on Natural Fibers: A Review

Nowadays, the world becomes more contaminated due to various factors such as pollution, global warming and unhealthy human practices. In this review paper, noise pollution is taken into major concern which affects quality of human life. Many researchers had attempted many studies to optimize the sound-absorbing capacity of natural fibers and to replace use of non-biodegradable synthetic sound barriers. This review research also focuses on the measurement of acoustic absorption coefficient (AAC) through various analytical such as Delany-Bazley, Garai-Pompoli and Biot-Allard method and experimental approaches such as impedance tube, reverberation room and environment anonymous (EA) noise. In addition to that, the influence of physical parameters such as fibrous material's thickness, density and porosity are also reviewed. It was found that most of the reviewer used two microphone impedance test tubes for determining absorption coefficient (alpha) of natural fiber-reinforced laminates. The more denser, thicker and porous materials shows better absorption rate than less denser, thicker and porous materials due to its high polymerization blending. Finally, these measuring methods are used to enhance the properties such as absorbing and reflecting in applications like sound recording room, acoustic baffles, damping sheets, barrier decoupler, etc.