Acoustic impedance and absorption coefficient measurements of porous materials used in the automotive industry

Abstract

A comparative study of the acoustic impedance (Zo), ttle absorption coefficient (ct) and the reflection coefficient (R) of several thermoplastic porous compounds is presented. Seven closed cell crosslinked polyolefin foams and a carpet of polypropylene staple fibres were analysed. Measurements of the commonly used polyurethane foams were also recorded to compare them with the results obtained with the above recycleable materials. The behaviour of the sound absorption in terms of the mean pore size and the type of cell (closed or open) is considered Jbr the analysed samples.