What Is The Actual Influence Of A Nano-Fibrous Membrane On The Acoustical Property Of Porous Substrate?

There is a general lack of publications on the acoustical and related non-acoustical properties of \nnano-fibrous media. Existing publications typically present scanning electron microscope images of \nthese media together with the acoustic absorption coefficient or transmission loss data (e.g. [1,2]). \nThese works often discuss the nano-fibre production process, quote data on the fibre diameter and \nsurface density for nano-fibrous membranes produced as a result of the reported process. \nHowever, little or no information is usually presented on the material pore structure, membrane \nthickness or bulk density. No effort is made to explain the observed acoustical performance of \nnano-fibrous membranes using a valid theoretical or semi-empirical model [1,2]. \nThis paper describes the problems associated with acoustic and related non-acoustic \ncharacterisation of these materials. It attempts, probably for the first time, to use a Biot- and Darcytype \nmathematical models to explain the observed acoustical and related non-acoustical behavior of \nnano-fibres. It identifies theoretical gaps related to the physical phenomena which can be \nresponsible for the observed acoustical behaviour of nano-fibrous membranes and it makes \nrecommendations to fill these gaps. \n