ACOUSTICAL CHARACTERIZATION OF FIBROUS MATERIALS AND MODELING WITH NOADJUSTABLE-PARAMETERS

The present Note describes a comparison between experimental data and theoretical predictions for the surface acoustical impedance of fibrou s materials used in the automotive industry. The theoretical tool used in this work is the standard Allard-Johnson-Cbampoux model designed f or air-saturated materials, which includes 5 parameters, i.e. the poro sity, the flow resistivity, the tortuosity, and the two characteristic lengths. The last three parameters are determined with low-frequency ultrasonic techniques. The present comparison, for the first time with fibrous materials, is done with no adjustable parameter, and the agre ement is generally excellent.