Review on the Acoustical Properties and Characterisation Methods of Sound Absorbing Porous Structures: A Focus on Microcellular Structures Made by a Replication Casting Method

A comprehensive literature review on the acoustical properties and characterisation methods of sound-absorbing porous materials with a focus on the type made by a replication casting process (i.e. "bottleneck-type" structures as referred to in this work) is presented herein. The review describes in detail pore-structure related parameters of soundproofing devices; models used for predicting their acoustic absorption behaviour and techniques for enhancing their sound absorption potential. An extensive survey, that includes a presentation of the application of Wilson's relaxation-matched equivalent fluid model to accurately predict the acoustic absorption spectra of "bottleneck-type" materials are given which could contribute to proposed research on the acoustic behaviour characterised by bimodal "bottleneck-type" structures. Graphic