Determination of the complex mass density of air contained in a rigid porous solid by an acoustic method

Abstract

An acoustical method for determining the frequency dependent complex effective mass density p(eff) of air contained in a rigid porous solid is investigated. An apparatus was designed and built which holds an air-filled porous solid sample within a cylindrical tube capped on each end by identical moving-coil loudspeakers. A quantity of air is made to oscillate back and forth as a plug through the porous solid sample. P(eff) is obtained from pressure and acceleration measurements taken at the ends of the sample tube. A description of the apparatus and the experimental results are presented