Identification of uncertainty levels of acoustic properties of biocomposites under different mounting conditions in impedance tube tests

Impedance tube method is widely used to measure acoustic properties of materials. Although this yields reliable for soft textured materials, uncertainty levels measured hard including biocomposites, can be quite large, mainly due uncertain mounting conditions. Here, the effects conditions on biocomposites in an impedance are investigated. First, nominally identical biocomposite samples with a diameter equal inner manufactured and their determined. As materials practically cause fitting problems tube, diameters reduced, as practice, by small amounts modified Furthermore, order match different such tape, petroleum jelly cotton applied around close air gap between tube's wall. All results compared, caused identified. The show that transmission loss (TL) measurements dramatically affected while sound absorption less sensitive deviations TL highest tape wax (10–15 dB). On other hand, coefficients (1–2%).