Frame acoustic properties of sound absorption structure having helical shapes

Abstract

New sound absorbing method utilizing layered-shaped medium is proposed. Conventional sound absorbing materials converts sound energy into thermal energy due to the porosity and tortuosity. New sound absorbing model haas helical-like shape in layered format with composite materials, and it can change the flow resistance itself through the change of the air cavity between layers. Acoustic impedance and sound absorption coefficient using impedance tube are measured for comparing to conventional sound absorbing materials. According to the result of sound absorption coefficient, helical-like shaped structure's absorption coefficient exhitited better sound absorbing properties. A simple method of improving the sound absorption and transmission especially at low frequencies after incorporating periodic formation is proposed and verified through experimentation. And with cantilever beam, dynamic stiffness and loss factor of layered absorber is measured and compared with other conventional sound absorber's properties.